JP5385006B2 - Resist underlayer film material and pattern forming method using the same - Google Patents

Description

The present invention relates to a resist underlayer film material that is effective as an antireflection film material used for microfabrication in the manufacturing process of semiconductor elements and the like, and far ultraviolet rays, KrF excimer laser light (248 nm), and ArF excimer laser light (193 nm) using the same. , F ₂ laser beam (157 nm), Kr ₂ laser beam (146 nm), Ar ₂ laser beam (126 nm), soft X-ray (EUV, 13.5 nm), electron beam (EB), resist pattern suitable for X-ray exposure The present invention relates to a forming method.

  In recent years, with the increasing integration and speed of LSIs, there is a need for finer pattern rules. In lithography using light exposure, which is currently used as a general-purpose technology, the essence derived from the wavelength of the light source The resolution limit is approaching.

  As a light source for lithography used in forming a resist pattern, light exposure using a mercury lamp g-line (436 nm) or i-line (365 nm) as a light source is widely used, and as a means for further miniaturization, A method of shortening the wavelength of exposure light has been considered effective. For this reason, a short wavelength KrF excimer laser (248 nm) was used as an exposure light source in place of the i-line (365 nm) in the mass production process of the 64-Mbit DRAM processing method. However, in order to manufacture a DRAM having a degree of integration of 1G or more, which requires a finer processing technique (processing dimension is 0.13 μm or less), a light source with a shorter wavelength is required, and in particular, an ArF excimer laser (193 nm) is used. Lithography has been studied.

  On the other hand, conventionally, it is known that a two-layer process is excellent for forming a pattern with a high aspect ratio on a stepped substrate, and further, for developing a two-layer resist film with a general alkali developer. Requires a high molecular silicone compound having a hydrophilic group such as a hydroxy group or a carboxyl group.

As the silicone-based chemically amplified positive resist material, a base resin in which a part of the phenolic hydroxyl group of polyhydroxybenzylsilsesquioxane, which is a stable alkali-soluble silicone polymer, is protected with a t-Boc group is used. A silicone-based chemically amplified positive resist material for a KrF excimer laser, which combines an acid generator and an acid generator, has been proposed (see Patent Document 1, Non-Patent Document 1, etc.). For ArF excimer lasers, positive resist materials based on silsesquioxane in which cyclohexylcarboxylic acid is substituted with an acid labile group have been proposed (Patent Documents 2 and 3, Non-Patent Document 2). Etc.). Furthermore, for F ₂ lasers, positive resist materials based on silsesquioxane having hexafluoroisopropanol as a soluble group have been proposed (see Patent Document 4, etc.). The above polymer contains polysilsesquioxane having a ladder skeleton formed by condensation polymerization of trialkoxysilane or trihalogenated silane in the main chain.

  As a resist base polymer in which silicon is pendant on a side chain, a silicon-containing (meth) acrylic ester polymer has been proposed (see Patent Document 5, Non-Patent Document 3, etc.).

  The resist underlayer film of the two-layer process is a hydrocarbon compound that can be etched with oxygen gas, and further needs to have high etching resistance because it serves as a mask for etching the underlying substrate. In oxygen gas etching, it is necessary to be composed only of hydrocarbons that do not contain silicon atoms. In addition, in order to improve the line width controllability of the upper silicon-containing resist film and reduce the pattern sidewall irregularities and pattern collapse due to standing waves, it also has a function as an antireflection film, specifically It is necessary to suppress the reflectance from the resist lower layer film into the resist upper layer film to 1% or less.

  Here, the results of calculating the reflectance up to a maximum film thickness of 500 nm are shown in FIGS. Assuming that the exposure wavelength is 193 nm, the n value of the resist upper layer film is 1.74, and the k value is 0.02, the k value of the resist lower layer film is fixed at 0.3 in FIG. 0.0 to 2.0, and the horizontal axis represents the substrate reflectance when the film thickness is varied in the range of 0 to 500 nm. Assuming a resist underlayer film for a two-layer process having a film thickness of 300 nm or more, the reflectivity is in the range of n to 1.6 to 1.9, which has a refractive index that is the same as or slightly higher than the resist upper layer film. There is an optimum value that can be reduced to 1% or less.

  FIG. 2 shows the reflectance when the n value of the resist underlayer film is fixed at 1.5 and the k value is varied in the range of 0 to 0.8. When a resist underlayer film for a two-layer process having a film thickness of 300 nm or more is assumed, the reflectance can be made 1% or less in the range of k value from 0.24 to 0.15. On the other hand, the optimum k value of an antireflection film for a single layer resist used in a thin film of about 40 nm is 0.4 to 0.5, and the optimum k value of a resist underlayer film for a two layer process used at 300 nm or more is Is different. It has been shown that a resist underlayer film for a two-layer process requires a lower k value, that is, a more transparent resist underlayer film.

  Here, as a resist underlayer film material for a wavelength of 193 nm, a copolymer of polyhydroxystyrene and an acrylate ester has been studied as introduced in Non-Patent Document 4. Polyhydroxystyrene has a very strong absorption at 193 nm, and the k value alone is a high value of around 0.6. Therefore, the k value is adjusted to around 0.25 by copolymerizing with an acrylate ester having a k value of almost 0.

  However, with respect to polyhydroxystyrene, the etching resistance of acrylate esters in substrate etching is weak, and a significant proportion of acrylate esters must be copolymerized to lower the k value, resulting in substrate etching. Resistance is significantly reduced. The resistance to etching appears not only in the etching rate but also in the occurrence of surface roughness after etching. The increase in surface roughness after etching becomes more prominent due to the copolymerization of acrylic acid ester.

  On the other hand, a three-layer process has been proposed in which a single-layer resist containing no silicon is formed as a resist upper layer film, a resist intermediate layer film containing silicon underneath it, and a resist underlayer film of an organic film is further formed thereunder (for example, Non-patent document 5). In general, a single-layer resist has better resolution than a silicon-containing resist, and a high-resolution single-layer resist can be used as an exposure imaging layer in a three-layer process. As the resist intermediate layer film, a spin-on-glass (SOG) film is used, and many SOG films have been proposed.

  Here, the optimum optical constant of the resist underlayer film for suppressing the substrate reflection in the three-layer process is different from that in the two-layer process. The purpose of suppressing the substrate reflection as much as possible, specifically, to reduce it to 1% or less, is the same in both the two-layer process and the three-layer process, but the two-layer process has an antireflection effect only on the resist underlayer film. On the other hand, in the three-layer process, one or both of the resist intermediate layer film and the resist underlayer film can have an antireflection effect.

Patent Document 6 and Patent Document 7 propose silicon-containing layer materials imparted with an antireflection effect. In general, a multilayer antireflection film has a higher antireflection effect than a single-layer antireflection film, and is widely used industrially as an antireflection film for optical materials. By imparting an antireflection effect to both the resist intermediate layer film and the resist underlayer film, a high antireflection effect can be obtained.
If the silicon-containing resist intermediate layer film can have a function as an antireflection film in the three-layer process, the resist underlayer film need not have the highest effect as an antireflection film as in the two-layer process. The resist underlayer film in the case of the three-layer process is required to have higher etching resistance in substrate processing than the effect as an antireflection film.
Therefore, a novolak resin containing a large amount of aromatic groups and having high etching resistance has been used as a resist underlayer film for a three-layer process.

Here, FIG. 3 shows the substrate reflectivity when the k value of the resist intermediate layer film is changed.
A sufficient antireflection effect of 1% or less can be obtained by a low value of 0.2 or less as the k value of the resist intermediate layer film and an appropriate film thickness setting.
As an antireflection film, it is necessary for the k value to be 0.2 or more in order to suppress reflection to 1% or less when the film thickness is 100 nm or less (see FIG. 2). As the resist intermediate layer film of the three-layer resist film that can be suppressed, the k value lower than 0.2 is the optimum value.

Next, FIG. 4 and FIG. 5 show the reflectance change when the thickness of the resist intermediate layer film and the resist lower layer film is changed when the k value of the resist lower layer film is 0.2 and 0.6. Show.
The resist underlayer film having a k value of 0.2 in FIG. 4 is assumed to be a resist underlayer film optimized for a two-layer process, and the resist underlayer film having a k value of 0.6 in FIG. The value is close to the k value of novolak and polyhydroxystyrene.
Although the film thickness of the resist underlayer film varies depending on the topography of the substrate, the film thickness of the resist intermediate layer film hardly varies, and it is considered that the resist can be applied with a set film thickness.

  Here, the higher the k value of the resist underlayer film (in the case of 0.6), the reflection can be suppressed to 1% or less with a thinner film. When the k value of the resist underlayer film is 0.2, the film thickness of the resist intermediate layer film must be increased in order to achieve reflection of 1% at a film thickness of 250 nm. However, when the film thickness of the resist intermediate layer film is increased in this way, the load on the uppermost resist film during dry etching when processing the resist intermediate layer film is large, which is not preferable.

  4 and 5 are reflections in the case of dry exposure with a lens NA of the exposure apparatus of 0.85, the n, k values and film thickness of the resist interlayer film for the three-layer process should be optimized. Thus, it is shown that the reflectance can be 1% or less regardless of the k value of the resist underlayer film. However, the NA of the projection lens exceeds 1.0 due to immersion lithography, and the angle of light incident not only on the resist but also on the antireflection film under the resist is becoming shallower. The antireflection film suppresses reflection not only by the absorption of the film itself but also by the action of cancellation due to the light interference effect. Since oblique light has a small light interference effect, reflection increases. Of the three-layer process film, the resist intermediate layer film is used to prevent reflection by using the interference of light. Since the resist underlayer film is sufficiently thick to use the interference action, there is no antireflection effect due to cancellation by the interference effect. It is necessary to suppress reflection from the surface of the resist underlayer film. For this purpose, it is preferable that the k value of the resist underlayer film is smaller than about 0.6 and the n value is set to a value close to that of the upper resist intermediate film. When the k value is too small and the transparency is too high, reflection from the substrate also occurs. Therefore, in the case of immersion exposure NA 1.3, the optimum k value is about 0.25 to 0.48. The n value is a target value that is close to the n value 1.7 of the resist for both the intermediate layer and the lower layer.

The benzene ring is very strongly absorbed, and the k value of cresol novolac and polyhydroxystyrene exceeds 0.6. One of the higher transparency and higher etching resistance at a wavelength of 193 nm than a benzene ring is a naphthalene ring. For example, Patent Document 8 proposes a resist underlayer film having a naphthalene ring and an anthracene ring. In our measured value, k value of naphthol co-condensed novolak resin and polyvinyl naphthalene resin is between 0.3 and 0.4. In addition, the n value at a wavelength of 193 nm of the naphthol co-condensed novolak resin and the polyvinyl naphthalene resin is low, 1.4 for the naphthol co-condensed novolak resin, and 1.2 for the polyvinyl naphthalene resin. For example, in the acenaphthylene polymers shown in Patent Document 9 and Patent Document 10, the n value at 193 nm is 1.5 and the k value is 0.4, which is close to the target value. There is a need for a resist underlayer film that has a high n value, a low k value, is transparent, and has high etching resistance.
Here, Patent Document 11 proposes a resist underlayer film forming material having a bisnaphthol group, which has a feature that both n value and k value are close to target values and excellent in etching resistance.
Patent Document 12 proposes an underlayer film material made of a novolak resin having a fluorene structure, and Patent Document 13 proposes an underlayer film material to which a fluorene monomer is added.

  Further, when there is a step in the substrate to be processed, it is necessary to flatten the step with a resist underlayer film. By flattening the resist lower layer film, it is possible to suppress the film thickness variation of the resist intermediate layer film formed on the resist film and the photoresist film as the resist upper layer film, and to expand the lithography focus margin.

  However, it is difficult for the amorphous carbon underlayer film formed by CVD using methane gas, ethane gas, acetylene gas or the like as a raw material to bury the step flatly. On the other hand, when the resist underlayer film is formed by spin coating, there is an advantage that the unevenness of the substrate can be embedded. Further, in order to improve the embedding characteristics in the coating type material, as shown in Patent Document 14, a method using a novolak having a low molecular weight and a wide molecular weight distribution, as shown in Patent Document 15, a base polymer is used. A method of blending a low molecular compound having a low melting point has been proposed.

It has been well known that novolak resins are crosslinked and cured by heating alone (Non-Patent Document 6). Here, a crosslinking mechanism by radical coupling is reported in which a phenoxy radical is generated in the hydroxy group of cresol novolac by heating, the radical is transferred to methylene of the linking group of the novolak resin by resonance, and the methylenes are cross-linked. Patent Document 16 reports a pattern formation method using a lower layer film in which a polycyclic aromatic compound such as polyarylene, naphthol novolak, and hydroxyanthracene novolak is heated and decarbonized or subjected to dehydration condensation to increase the carbon density.
A glassy carbon film is formed by heating at 800 ° C. or higher (Non-patent Document 7). However, considering the influence on device damage and wafer deformation, the upper limit of the heatable temperature in the lithography wafer process is 600 ° C. or less, preferably 500 ° C. or less.

  It has been reported that with the reduction of the processing line width, a phenomenon that the resist underlayer film is twisted or bent when the substrate to be processed is etched using the resist underlayer film as a mask (Non-patent Document 8). It shows a phenomenon in which hydrogen atoms in a resist underlayer film are replaced with fluorine atoms during substrate etching with a fluorocarbon-based gas. It is considered that the resist underlayer film surface is made Teflon (registered trademark) to swell due to the increase in volume of the underlayer film or the glass transition point is lowered, thereby causing a finer pattern distortion. In the above-mentioned document, it has been shown that twisting can be prevented by applying a resist underlayer film having a low hydrogen content. An amorphous carbon film prepared by CVD can extremely reduce the number of hydrogen atoms in the film, and is very effective in preventing dripping. However, as described above, CVD has poor step embedding characteristics and may be difficult to introduce due to the cost of the CVD apparatus and the occupation footprint area. If the problem can be solved with a coating, particularly a resist underlayer film material that can be formed by a spin coating method, the merit of simplifying the process and the apparatus is great.

  A multi-layer process in which a hard mask is formed on a resist underlayer film by a CVD method has been studied. In the case of silicon hard masks (silicon oxide film, silicon nitride film, silicon oxynitride film), the etching resistance of inorganic hard masks formed by CVD or the like is higher than that of hard masks formed by spin coating. . Further, the substrate to be processed has a low dielectric constant film, and the photoresist may be contaminated (poisoning) from there, but the CVD film is more effective as a blocking film for preventing poisoning.

  Therefore, a process for forming a resist underlayer film by spin coating for flattening and forming an inorganic hard mask intermediate layer film as a resist intermediate layer film thereon by a CVD method has been studied. When the inorganic hard mask intermediate layer is formed by the CVD method, it is necessary to heat the substrate at a minimum of 300 ° C., usually 400 ° C., particularly in forming a nitride film. Therefore, when a resist underlayer film is formed by spin coating, heat resistance of 400 ° C. is necessary. However, ordinary cresol novolak, naphthol novolak, and fluorene bisphenol novolak resin having high heat resistance can also be heated to 400 ° C. It cannot withstand and a large film loss occurs after heating. Thus, there is a need for a resist underlayer film that can withstand high-temperature heating when forming an inorganic hard mask intermediate layer film by CVD.

  Further, due to the problem of film loss after heating and deterioration of the resin due to such heat resistance, conventional heat treatment of the resist underlayer film material is usually performed at 300 ° C. or less (preferably in the range of 80 to 300 ° C.). It was. However, there still remains a problem that the film is reduced after the solvent treatment or the pattern is distorted during the etching of the substrate.

  As described above, it has optimum n and k values and anti-reflection properties as an antireflection film, excellent etching resistance and solvent resistance, and can withstand high temperatures during the formation of an inorganic hard mask interlayer film by CVD or the like. There is a need for a resist underlayer film material for forming a resist underlayer film that has heat resistance that can be resisted and does not sag during etching of the substrate.

JP-A-6-118651 Japanese Patent Laid-Open No. 10-324748 JP-A-11-302382 JP 2002-55456 A JP-A-9-110938 US Pat. No. 6,506,497 US Pat. No. 6420088 JP 2002-14474 A JP 2001-40293 A JP 2002-214777 A JP 2007-199653 A JP 2005-128509 A JP 2007-17867 A JP 2002-47430 A JP-A-11-154638 Patent 3504247

SPIE vol. 1925 (1993) p377 SPIE vol. 3333 (1998) p62 J. et al. Photopolymer Sci. and Technol. Vol. 9 No. 3 (1996) p435-446 SPIE vol. 4345 (2001) p50 J. et al. Vac. Sci. Technol. , 16 (6), Nov. / Dec. 1979 SPIE Vol. 469 p72 (1984) Glass Carbon Bull. Chem. Soc. JPN. 41 (12) 3023-3024 (1968) (Proc. Of Symp. Dry. Process, (2005) p11)

  The present invention has been made in view of the above circumstances, and is a resist underlayer film material of a multilayer resist film used in lithography, which can reduce reflectance, has high etching resistance, and has high heat resistance and solvent resistance. In particular, it is an object of the present invention to provide a resist underlayer film material for forming a resist underlayer film that is free from occurrence of contamination during etching of a substrate, and a pattern forming method using the resist underlayer film material.

（一般式（１）中、Ｒ^１、Ｒ^２は同一、又は異種の水素原子、ヒドロキシル基、炭素数１〜６のアシル基、炭素数１〜６のアルコキシ基、炭素数１〜６のアルコキシカルボニル基、カルボニル基、アミノ基、酸不安定基、グリシジル基、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜２０のアリール基、炭素数２〜１０のアルケニル基、炭素数２〜１０のアルキニル基、カルボキシル基、又はシアノ基、あるいは、Ｒ^１、Ｒ^２はまとめて１つの基であっても良く、その場合には、酸素原子、炭素数１〜６のアルキリデン基、又はイミノ基である。これらの基は、ヒドロキシル基、炭素数１〜６のアシル基、炭素数１〜６のアルコキシ基、炭素数１〜６のアルコキシカルボニル基、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜２０のアリール基、炭素数２〜２０のアルケニル基、炭素数２〜１０のアルキニル基、アミノ基、ニトロ基、シアノ基、酸不安定基、グリシジル基、カルボキシル基を、１つ又は複数有していても良い。Ｒ^３、Ｒ^４はそれぞれベンゼン環又はナフタレン環であり、Ｒ^５、Ｒ^６はそれぞれ水素原子、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基、又は炭素数２〜１０のアルキニル基である。） The present invention has been made to solve the above problems, and is a resist underlayer film material for a multilayer resist film used in lithography, and at least polyfluorene having a repeating unit a1 represented by the following general formula (1) The resist underlayer film material characterized by containing this is provided.

(In General Formula (1), R ¹ and R ² are the same or different hydrogen atoms, hydroxyl groups, C 1-6 acyl groups, C 1-6 alkoxy groups, C 1-6 alkoxys. Carbonyl group, carbonyl group, amino group, acid labile group, glycidyl group, linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 20 carbon atoms, 2 to 10 carbon atoms An alkenyl group, an alkynyl group having 2 to 10 carbon atoms, a carboxyl group, or a cyano group, or R ¹ and R ² may be combined into one group. These are an alkylidene group having 6 or an imino group, and these groups are a hydroxyl group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, and 1 carbon atom. -10 linear, branched Or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an amino group, a nitro group, a cyano group, an acid labile group, a glycidyl group, One or a plurality of carboxyl groups may be present, R ³ and R ⁴ are each a benzene ring or a naphthalene ring, R ⁵ and R ⁶ are each a hydrogen atom, a straight chain having 1 to 10 carbon atoms, A branched or cyclic alkyl group, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms.)

  Thus, if the resist underlayer film material contains polyfluorene having the repeating unit a1 represented by the general formula (1), the resist underlayer film material is coated on the substrate, and the coated resist underlayer film material is By curing by heat treatment, it has optimum n and k values and embedding characteristics as an antireflection film, excellent etching resistance, solvent resistance, and high temperature during the formation of an inorganic hard mask interlayer film by CVD method etc. It is possible to form a resist underlayer film that has heat resistance that can withstand, and that does not sag during etching of the substrate.

（一般式（２）中Ｒ^３〜Ｒ^６は前述と同様、Ｒ^７、Ｒ^８はそれぞれ水素原子、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基、又は炭素数２〜１０のアルキニル基である。ｍ、ｎはそれぞれ０〜２の整数であり、Ｒ^９、Ｒ^１０はそれぞれ水素原子、炭素数１〜６の直鎖状、分岐状、環状のアルキル基、炭素数６〜２０のアリール基、炭素数２〜２０のアルケニル基、炭素数２〜１０のアルキニル基、炭素数１〜６のアシル基もしくはアルコキシカルボニル基、酸不安定基、又はグリシジル基である。） The repeating unit a1 represented by the general formula (1) is preferably a repeating unit a2 represented by the following general formula (2).

(In General Formula (2), R ^{3 to} R ⁶ are the same as described above, R ⁷ and R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and 6 to 10 carbon atoms. An aryl group, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms, m and n are each an integer of 0 to 2, and R ⁹ and R ¹⁰ are a hydrogen atom and a carbon number, respectively. 1-6 linear, branched, and cyclic alkyl groups, C6-C20 aryl groups, C2-C20 alkenyl groups, C2-C10 alkynyl groups, C1-C6 acyls Group or alkoxycarbonyl group, acid labile group, or glycidyl group.)

  Thus, if the resist underlayer film material contains polyfluorene having the repeating unit a2 represented by the general formula (2), the resist underlayer film material is coated on the substrate, and the coated resist underlayer film material is By curing by heat treatment, it has optimum n and k values and embedding characteristics as an antireflection film, excellent etching resistance, solvent resistance, and high temperature during the formation of an inorganic hard mask interlayer film by CVD method etc. It is possible to more reliably form a resist underlayer film that has heat resistance that can withstand, and that does not sag during etching of the substrate.

（一般式（３）中Ｒ^３〜Ｒ^１０、ｍ、ｎは前述の通り、Ｒ^１１は炭素数１〜１０のアルキレン基であり、アリル基を有していても良い。） Further, as the resist underlayer film material, a polyfluorene having a repeating unit a2 represented by the general formula (2) is obtained by novolacizing the repeating unit a2, and is represented by the following general formula (3). What contains the unit a3 can also be used.

(In the general formula (3), R ^{3 to} R ¹⁰ , m and n are as described above, R ¹¹ is an alkylene group having 1 to 10 carbon atoms, and may have an allyl group.)

  Thus, if the resist underlayer film material contains a polyfluorene novolak resin having the repeating unit a3 represented by the general formula (3), the resist underlayer film material is coated on the substrate, and the coated resist underlayer film By curing the film material by heat treatment, it has optimum n and k values and embedding characteristics as an antireflection film, excellent etching resistance and solvent resistance, and also forms an inorganic hard mask interlayer film by CVD method etc. It is possible to form a resist underlayer film that has heat resistance that can withstand high temperatures in the middle and that does not sag during etching of the substrate.

  Further, the resist underlayer film material preferably contains an organic solvent. Moreover, it is preferable that the resist underlayer film material further contains a crosslinking agent and an acid generator.

  As described above, the resist underlayer film material of the present invention contains an organic solvent, a crosslinking agent, and an acid generator, thereby improving the coating property on a substrate or the like, or by baking after coating on a substrate or the like. The crosslinking reaction in the resist underlayer film can be promoted. Therefore, the resist underlayer film formed from such a resist underlayer film material has good film thickness uniformity, and there is little risk of intermixing with the resist upper layer film or the resist intermediate layer film. Less component diffusion.

  The present invention is also a method for forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate using the resist underlayer film material of the present invention, and a photo resist is formed on the resist underlayer film. Forming a resist upper layer film using a resist upper layer film material made of a resist composition, exposing a pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film, Etching the resist underlayer film using the obtained resist pattern as an etching mask, and etching the substrate using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate. provide.

  As described above, the resist underlayer film formed by using the resist underlayer film material of the present invention has optimum n value and k value, and is excellent in etching resistance under the substrate etching conditions, particularly in short wavelength exposure. . For this reason, if the resist underlayer film formed using the resist underlayer film material of the present invention is used as the resist underlayer film in the two-layer process, a pattern can be formed on the substrate with high accuracy.

  In this case, the resist upper layer material made of the photoresist contains a polymer containing silicon atoms, and etching of the resist lower layer film using the resist upper layer film as a mask is an etching gas mainly composed of oxygen gas or hydrogen gas. It is preferable to carry out using.

  The resist underlayer film formed from the resist underlayer film material of the present invention uses, as the resist upper layer film, a base resin containing silicon atoms, and etching of the resist underlayer film using the resist upper layer film as a mask is performed using oxygen gas or It is suitable for transferring the resist pattern of the resist upper layer film to the resist lower layer film by dry etching mainly using hydrogen gas.

  The present invention also relates to a method for forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate using the resist underlayer film material of the present invention, and a silicon is formed on the resist underlayer film. A resist intermediate layer film is formed using a resist intermediate layer film material containing atoms, a resist upper layer film is formed on the resist intermediate layer film using a resist upper layer film material made of a photoresist composition, After exposing the pattern circuit area of the resist upper layer film, developing with a developing solution to form a resist pattern on the resist upper layer film, and etching the resist intermediate layer film using the obtained resist pattern as an etching mask The resist underlayer film pattern obtained by etching the resist underlayer film using the resist intermediate layer film pattern as an etching mask. The etched substrate as a mask to provide a pattern forming method comprising forming a pattern on a substrate.

  As described above, the resist underlayer film formed by using the resist underlayer film material of the present invention has optimum n value and k value, particularly in short wavelength exposure, and is excellent in etching resistance during substrate etching. Further, if necessary, it is combined with a resist intermediate layer film having an antireflection effect to provide an excellent antireflection effect. For this reason, if the resist underlayer film formed using the resist underlayer film material of the present invention is used as a resist underlayer film in a three-layer process, a pattern can be formed on the substrate with higher accuracy.

  The present invention also relates to a method for forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate using the resist underlayer film material of the present invention, and a silicon is formed on the resist underlayer film. An inorganic hard mask intermediate film selected from an oxide film, a silicon nitride film, and a silicon oxynitride film is formed, an organic antireflection film is formed on the inorganic hard mask intermediate film, and the organic antireflection film is formed on the organic antireflection film. After forming a resist upper layer film using a resist upper layer film material made of a photoresist composition, exposing a pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film The organic antireflection film and the inorganic hard mask intermediate film are etched using the obtained resist pattern as an etching mask, and the resulting inorganic hard mask is obtained. A pattern forming method is provided, wherein the resist underlayer film is etched using the intermediate layer film pattern as an etching mask, and the substrate is etched using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate. To do.

  Thus, in the pattern formation method of the present invention, an organic antireflection film can be formed between the inorganic hard mask intermediate layer film and the resist upper layer film.

  In this case, the inorganic hard mask intermediate layer film can be formed by a CVD method or an ALD method.

  In this manner, the etching resistance can be increased by forming the inorganic hard mask intermediate film by the CVD method or the ALD method. Further, the resist underlayer film of the present invention is suitable because it can withstand the high temperatures of such CVD and ALD methods.

  In addition, the resist upper layer film material made of the photoresist composition does not contain a polymer containing silicon atoms, and etching of the resist lower layer film using the intermediate layer film as a mask is mainly oxygen gas or hydrogen gas. It is preferable to use an etching gas.

  Those in which the resist upper layer film does not contain a silicon atom-containing polymer has an advantage that the resolution is excellent as compared with those containing a silicon atom-containing polymer. Further, when the resist underlayer film is etched using the inorganic hard mask intermediate layer film pattern as an etching mask, an inorganic hard mask containing silicon atoms is preferable because it shows etching resistance with oxygen gas or hydrogen gas.

As described above, by using the resist underlayer film material of the present invention, the reflectance can be reduced, the etching resistance is high, the heat resistance and the solvent resistance are high, and particularly the occurrence of sag during the etching of the substrate. A resist underlayer film can be formed. In addition, the resist underlayer film formed using the resist underlayer film material of the present invention is sufficiently antireflective with a film thickness of 100 nm or more by combining with an intermediate layer film having an antireflection effect as necessary in short wavelength exposure. It has an extinction coefficient that can exert the effect, and the etching rate of CF ₄ / CHF ₃ gas and Cl ₂ / BCl ₃ gas used for substrate processing is slower and stronger than normal m-cresol novolac resin, and high etching It will be resistant. Also, the resist shape after patterning is good.

The resist underlayer film refractive index k value in the two-layer process is fixed at 0.3, and the relationship between the resist underlayer film thickness and the substrate reflectance when the n value is changed in the range of 1.0 to 2.0 is shown. It is a graph. A graph showing the relationship between the resist underlayer film thickness and the substrate reflectivity when the resist underlayer film refractive index n value in a two-layer process is fixed at 1.5 and the k value is changed in the range of 0 to 0.8. is there. It is a graph which shows the relationship of a board | substrate reflectance when the resist intermediate layer film | membrane refractive index n value in a 3 layer process is 1.5, k value is changed in the range of 0-0.4, and film thickness is 0-400 nm. . In the three-layer process, the resist underlayer film refractive index n value is 1.5, the k value is 0.2, the n value of the resist intermediate layer film is 1.5, and the k value is fixed at 0.1. It is a graph which shows the relationship of a board | substrate reflectance when changing the film thickness of a resist intermediate | middle layer film. In the three-layer process, the resist underlayer film refractive index n value is 1.5, the k value is 0.6, the n value of the resist intermediate layer film is 1.5, and the k value is fixed at 0.1, and the resist underlayer film and the resist intermediate layer It is a graph which shows the relationship of a board | substrate reflectance when changing the film thickness of a film | membrane. It is explanatory drawing of an example of a 2 layer process. It is explanatory drawing of an example of a 3 layer process.

Hereinafter, the present invention will be described more specifically.
As described above, as a resist underlayer film material of a multilayer resist film, it has an excellent antireflection film function, etching resistance, heat resistance, solvent resistance, and embedding characteristics, and resist film that is not particularly distorted during substrate etching. It was regarded as necessary to be able to form.

  As a result of intensive studies to achieve the above object, the present inventors have found that polyfluorene having a high transparency and a large number of carbon atoms and its derivative have an excellent antireflection film function, heat resistance, and solvent resistance. It has been found that the present invention is promising as a resist underlayer film material for forming a resist underlayer film for a two-layer or three-layer process that has excellent properties and embedding characteristics, and has excellent etching resistance.

（一般式（１）中、Ｒ^１、Ｒ^２は同一、又は異種の水素原子、ヒドロキシル基、炭素数１〜６のアシル基、炭素数１〜６のアルコキシ基、炭素数１〜６のアルコキシカルボニル基、カルボニル基、アミノ基、酸不安定基、グリシジル基、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜２０のアリール基、炭素数２〜１０のアルケニル基、炭素数２〜１０のアルキニル基、カルボキシル基、又はシアノ基、あるいは、Ｒ^１、Ｒ^２はまとめて１つの基であっても良く、その場合には、酸素原子、炭素数１〜６のアルキリデン基、又はイミノ基である。これらの基は、ヒドロキシル基、炭素数１〜６のアシル基、炭素数１〜６のアルコキシ基、炭素数１〜６のアルコキシカルボニル基、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜２０のアリール基、炭素数２〜２０のアルケニル基、炭素数２〜１０のアルキニル基、アミノ基、ニトロ基、シアノ基、酸不安定基、グリシジル基、カルボキシル基を、１つ又は複数有していても良い。Ｒ^３、Ｒ^４はそれぞれベンゼン環又はナフタレン環であり、Ｒ^５、Ｒ^６はそれぞれ水素原子、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基、又は炭素数２〜１０のアルキニル基である。） That is, the resist underlayer film material of the present invention is a resist underlayer film material of a multilayer resist film used in lithography, and contains at least polyfluorene having a repeating unit a1 represented by the following general formula (1). Features.

(In General Formula (1), R ¹ and R ² are the same or different hydrogen atoms, hydroxyl groups, C 1-6 acyl groups, C 1-6 alkoxy groups, C 1-6 alkoxys. Carbonyl group, carbonyl group, amino group, acid labile group, glycidyl group, linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 20 carbon atoms, 2 to 10 carbon atoms An alkenyl group, an alkynyl group having 2 to 10 carbon atoms, a carboxyl group, or a cyano group, or R ¹ and R ² may be combined into one group. These are an alkylidene group having 6 or an imino group, and these groups are a hydroxyl group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, and 1 carbon atom. -10 linear, branched Or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an amino group, a nitro group, a cyano group, an acid labile group, a glycidyl group, One or a plurality of carboxyl groups may be present, R ³ and R ⁴ are each a benzene ring or a naphthalene ring, R ⁵ and R ⁶ are each a hydrogen atom, a straight chain having 1 to 10 carbon atoms, A branched or cyclic alkyl group, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms.)

（一般式（２）中Ｒ^３〜Ｒ^６は前述と同様、Ｒ^７、Ｒ^８はそれぞれ水素原子、炭素数１〜１０の直鎖状、分岐状もしくは環状のアルキル基、炭素数６〜１０のアリール基、炭素数２〜１０のアルケニル基、又は炭素数２〜１０のアルキニル基である。ｍ、ｎはそれぞれ０〜２の整数であり、Ｒ^９、Ｒ^１０はそれぞれ水素原子、炭素数１〜６の直鎖状、分岐状、環状のアルキル基、炭素数６〜２０のアリール基、炭素数２〜２０のアルケニル基、炭素数２〜１０のアルキニル基、炭素数１〜６のアシル基もしくはアルコキシカルボニル基、酸不安定基、又はグリシジル基である。） The repeating unit a1 represented by the general formula (1) is preferably a repeating unit a2 represented by the following general formula (2).

(In General Formula (2), R ^{3 to} R ⁶ are the same as described above, R ⁷ and R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and 6 to 10 carbon atoms. An aryl group, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms, m and n are each an integer of 0 to 2, and R ⁹ and R ¹⁰ are a hydrogen atom and a carbon number, respectively. 1-6 linear, branched, and cyclic alkyl groups, C6-C20 aryl groups, C2-C20 alkenyl groups, C2-C10 alkynyl groups, C1-C6 acyls Group or alkoxycarbonyl group, acid labile group, or glycidyl group.)

（一般式（３）中Ｒ^３〜Ｒ^１０、ｍ、ｎは前述の通り、Ｒ^１１は炭素数１〜１０のアルキレン基であり、アリル基を有していても良い。） Further, as the resist underlayer film material, a material containing a repeating unit a3 represented by the following general formula (3) obtained by novolacizing polyfluorene having the repeating unit a2 represented by the general formula (2) may be used. it can.

(In the general formula (3), R ^{3 to} R ¹⁰ , m and n are as described above, R ¹¹ is an alkylene group having 1 to 10 carbon atoms, and may have an allyl group.)

In conventional novolak resins that have been used as resist underlayer film materials, the phenols are connected by alkylene groups such as methylene, and therefore the rotation of the alkylene groups reduces the film rigidity and the etching resistance due to a decrease in carbon density. There was a problem. In addition, the cycloolefin polymer obtained by polymerizing indene, acenaphthylene, etc. has a rigid main chain, but the carbon of the main chain becomes a tertiary carbon. In comparison, there was a problem that etching resistance was weak.
On the other hand, the polyfluorene represented by the general formula (1) or (2) or the polyfluorene represented by the general formula (3) contained in the resist underlayer film material of the present invention was novolakized. Novolac resin (polyfluorene novolac resin) is very rigid because aromatic groups are directly bonded to each other, and is connected by quaternary carbon, so it has excellent etching resistance, solvent resistance, and heat resistance. Have sex. In addition, since the polyfluorene and the polyfluorene novolak resin contained in the resist underlayer film material of the present invention are highly transparent, the resist underlayer film formed using the resist underlayer film material of the present invention is excellent. It has an antireflection function.
That is, the resist underlayer film material of the present invention proposes a material based on polyfluorene and / or a polyfluorene derivative (novolak resin), particularly high energy rays having a wavelength of 300 nm or less, specifically 248 nm, Excellent resistance to etching in 193 nm, 157 nm excimer laser, 3-20 nm soft X-ray, electron beam, X-ray, excellent antireflection function, solvent resistance, heat resistance, and optimal embedding characteristics. A resist underlayer film for a multi-layer resist process, for example, a two-layer or three-layer process, having excellent dry etching resistance in processing can be formed.

The resist underlayer film material of the present invention is
(A) The polyfluorene represented by the general formula (1) or (2) or the polyfluorene novolak resin represented by the general formula (3) is an essential component.
(B) an organic solvent,
In order to increase spin coating characteristics, step board embedding characteristics, film rigidity and solvent resistance,
(C) Resins other than the polyfluorenes of the above general formulas (1) and (2) and the polyfluorene novolak resin of the above general formula (3) (D) a crosslinking agent,
(E) An acid generator may also be included.

Specific examples of the monomer for obtaining the polyfluorene represented by the general formulas (1) and (2) are shown below, but are not limited thereto.

（上記（化１０）〜（化１２）中、Ｒ^９及びＲ^１０は前述と同様である。）

(In the above (Chemical Formula 10) to (Chemical Formula 12), R ⁹ and R ¹⁰ are the same as described above.)

Among the polyfluorenes represented by the general formula (1) or (2), those in which R ³ and / or R ⁴ are a naphthalene ring can further improve the etching resistance and optical constant of the resist underlayer film. .
In addition, when both R ¹ and R ² are not hydroxyl groups or glycidyl groups, the embedding property on the stepped substrate when forming the resist underlayer film can be further improved.

Although it does not specifically limit as a synthesis method of the polyfluorene shown by the said General formula (1) or (2), For example, the chemical oxidative polymerization of WO2005 / 100437 A1 is mentioned. As a catalyst used for oxidative polymerization, a combination of FeCl ₃ , MoCl ₃ , WCl ₃ , AlCl ₃ —CuCl ₂ , AlCl ₃ —MnO _3, etc. and a Lewis acid can be used, but FeCl ₃ is most preferably used. I can do it. In the case of oxidative polymerization, since the activities at the 2nd and 7th positions of fluorene are high, the polymerization proceeds mainly while the 2nd and 7th positions are coupled to each other.
Further, as another polymerization method, for example, a method of polycondensing halogenated fluorene as described in Japanese Patent No. 3443736 can be mentioned. As the catalyst used here, a Ni catalyst is used, and nickel (cyclooctadiene) ₂ is preferably used.

Polyfluorene as a resist underlayer film material of the present invention synthesized by such a method, combined with the heat resistance of the fluorene monomer, has a very high heat resistance because the fluorenes are directly connected by a single bond. Have. Therefore, if the resist underlayer film material of the present invention is used, a resist underlayer film that can withstand high temperature heating can be formed.
Compared to this, in a normal cresol novolac resin, phenols are bonded by an alkylene group, so that the heat resistance is reduced by the amount of vibration or rotation of the alkylene group.

As a component (A) of the resist underlayer film material of the present invention, a resin obtained by novolacizing the polyfluorene compound represented by the above general formula (2) by a condensation reaction with aldehydes, as represented by the above general formula (3) Can also be used.
Examples of aldehydes used here include formaldehyde, trioxane, paraformaldehyde, benzaldehyde, acetaldehyde, propylaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde, β-phenylpropylaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p. -Hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p -Ethylbenzaldehyde, pn-butylbenzaldehyde, furfural, etc. Can be mentioned. Of these, formaldehyde can be particularly preferably used.
These aldehydes can be used alone or in combination of two or more.
0.2-5 mol is preferable with respect to 1 mol of polyfluorene compounds, and, as for the usage-amount of the said aldehyde, More preferably, it is 0.5-2 mol.

A catalyst can also be used for the condensation reaction of a polyfluorene compound and aldehydes.
Specific examples include acidic catalysts such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, methanesulfonic acid, camphorsulfonic acid, tosylic acid, and trifluoromethanesulfonic acid.
The usage-amount of these acidic catalysts is 1 * 10 < ^-5 > ^-5 * 10 < ^-1 > mol with respect to 1 mol of bisnaphthol compounds. Indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene In the case of a copolymerization reaction with a compound having a non-conjugated double bond such as aldehydes, aldehydes are not necessarily required.

Water, methanol, ethanol, propanol, butanol, tetrahydrofuran, dioxane or a mixed solvent thereof can be used as a reaction solvent in the polycondensation.
These solvents are in the range of 0 to 2,000 parts by mass with respect to 100 parts by mass of the reaction raw material.
Although reaction temperature can be suitably selected according to the reactivity of the reaction raw material, it is the range of 10-200 degreeC normally.

As a polycondensation reaction method, there are a method in which a polyfluorene compound, an aldehyde, and a catalyst are charged at once, and a method in which a polyfluorene compound and an aldehyde are dropped in the presence of a catalyst.
After completion of the polycondensation reaction, in order to remove unreacted raw materials, catalysts, etc. existing in the system, the temperature of the reaction kettle can be raised to 130-230 ° C., and volatile matter can be removed at about 1-50 mmHg. .

As the repeating unit of polyfluorene, a repeating unit a1 in the general formula (1), a repeating unit a2 in the general formula (2), or a homopolymer of the repeating unit a3 in the general formula (3) alone, a1 , A2 and a3 can be copolymerized with various monomers as well as a copolymer obtained by copolymerizing at least two of them.
The copolymerizable monomer is an aromatic compound having 6 to 30 carbon atoms, and a dihalogenated aromatic compound is preferably used. Specifically, dibromobenzene, dichlorobenzene, dibromomethylbenzene, dibromonaphthalene, dibromomethylbenzene, dibromoanthracene, dibromomethylanthracene, dibromophenanthrene, dibromopyrene, dibromopentacene, dibromofluorene, dibromobiphenyl, dibromovirnaphthalene, dibromophenol , Dibromonaphthol, dibromovirnaphthol, fluoranthene, indene, acenaphthylene, acephenanthrylene, acanthrylene, pyrene, anthracene, naphthacene, perylene, pentacene, coronene, phenanthrene, indacene, styrene, vinylnaphthalene, vinylanthracene, vinylcarbazole, And cyclopentaphenanthrene.

Further, other phenols may be copolymerized.
The copolymerizable phenols are phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4 -Methylresorcinol 5-methylresorcinol, catechol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4 -Isopropylphenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, pyrogallol, thymol, isothimol and the like can be mentioned.

  In addition, copolymerizable monomers can be copolymerized. Specifically, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol And 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, dihydroxynaphthalene such as 2,6-dihydroxynaphthalene, methyl 3-hydroxy-naphthalene-2-carboxylate, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, Biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene, benzenedimethanol, naphth Thallene methanol, fluorenediethanol methanol, anthracene dimethanol, pyrene methanol, biphenyl dimethanol, 4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′dimethyl-4,4 ′-(9H— Fluorene-9-ylidene) bisphenol, 2,2′diallyl-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′difluoro-4,4 ′-(9H-fluorene-9-ylidene) Bisphenol, 2,2′diphenyl-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′dimethoxy-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, tetrahydrospirobiindene Compound, 2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiin -6,6'-diol, 3,3,3 ', 3'-tetramethyl-2,3,2', 3'-tetrahydro- (1,1 ')-spirobiindene-6,6'- Diol, 3,3,3 ′, 3 ′, 4,4′-hexamethyl-2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6′-diol, 2 , 3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-5,5′-diol, 5,5′-dimethyl-3,3,3 ′, 3′-tetramethyl-2 , 3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6′-diol, a dibisphenol compound described in JP-A-2006-259482, and JP-A-2006-285095 An adamantanephenol compound, as described in JP 2007-199653 A Such as scan naphthol compounds include, but may be a ternary or more copolymer obtained by adding these things.

The weight average molecular weight (Mw) of polyfluorene in terms of polystyrene is preferably 400 to 20,000, particularly preferably 500 to 15,000.
The molecular weight in terms of polystyrene of the polyfluorene novolak resin is preferably 600 to 30,000, particularly preferably 700 to 20,000, in weight average molecular weight (Mw).
The molecular weight distribution (Mw / Mn) is preferably in the range of 1.2-7, but it is cross-linked by narrowing the molecular weight distribution by cutting monomer components, oligomer components or low molecular weight materials having a molecular weight (Mw) of 300 or less. Efficiency increases and contamination around the baking cup can be prevented by suppressing volatile components in the baking.

Of the polyfluorene represented by the above general formula (1) or (2) or the polyfluorene novolak resin represented by the above general formula (3), those having a hydroxyl group are the ortho position of the hydroxyl group or A condensed aromatic or alicyclic substituent can be introduced at the para-position.
Specific examples of the substituent that can be introduced here are listed below.

  Of these, polycyclic aromatic groups such as anthracenemethyl group and pyrenemethyl group are most preferably used for 248 nm exposure. In order to improve transparency at 193 nm, those having an alicyclic structure and those having a naphthalene structure are preferably used. On the other hand, since the benzene ring has a window with improved transparency at a wavelength of 157 nm, it is necessary to increase the absorption by shifting the absorption wavelength. The furan ring has a shorter absorption than the benzene ring and slightly improves the absorption at 157 nm, but the effect is small. Naphthalene rings, anthracene rings, and pyrene rings are preferably used because their absorption increases as the absorption wavelength increases, and these aromatic rings also have an effect of improving etching resistance.

As a method for introducing the substituent, there is a method in which an alcohol having a hydroxyl group as the bonding position of the substituent is introduced into the polymer after polymerization in the ortho or para position of the hydroxyl group of polyfluorene in the presence of an acid catalyst. Can be mentioned. As the acid catalyst, an acidic catalyst such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, methanesulfonic acid, n-butanesulfonic acid, camphorsulfonic acid, tosylic acid, trifluoromethanesulfonic acid and the like can be used. The usage-amount of these acidic catalysts is 1 * 10 < ^-5 > ^-5 * 10 < ^-1 > mol with respect to 1 mol of phenols. The amount of the substituent introduced is in the range of 0 to 0.8 mol with respect to 1 mol of the hydroxyl group of polyfluorene.

  In order to improve the transparency at 193 nm of the polyfluorene represented by the general formula (1) or (2) used in the present invention or the novolak resin of polyfluorene represented by the general formula (3), hydrogenation is performed. It can be performed. A preferable hydrogenation ratio is 80 mol% or less, particularly 60 mol% or less of the aromatic group.

Further, the resist underlayer film material of the present invention can be blended with other polymers as the component (C).
As the polymer for blending, it is mixed with the polyfluorene represented by the above general formula (1) or (2) or the polyfluorene novolac resin represented by the above general formula (3), A material having a role of improving the embedding characteristics in the stepped substrate or a material having a high carbon density and high etching resistance is selected.

Such materials include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2 , 4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2 -Phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4- Methyl resorcinol, 5-me Luresorcinol, catechol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropyl Phenol, 2-methoxy-5-methylphenol, 2-t-butyl-5-methylphenol, pyrogallol, thymol, isothymol, 4,4 '-(9H-fluorene-9-ylidene) bisphenol, 2,2'dimethyl- 4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′diallyl-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′difluoro-4,4 ′-( 9H-Fluorene-9-ylidene) bisphenol, 2,2 ' Diphenyl-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,2′dimethoxy-4,4 ′-(9H-fluorene-9-ylidene) bisphenol, 2,3,2 ′, 3′- Tetrahydro- (1,1 ′)-spirobiindene-6,6′-diol, 3,3,3 ′, 3′-tetramethyl-2,3,2 ′, 3′-tetrahydro- (1,1 ′ ) -Spirobiindene-6,6'-diol, 3,3,3 ', 3', 4,4'-hexamethyl-2,3,2 ', 3'-tetrahydro- (1,1')-spiro Biindene-6,6′-diol, 2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-5,5′-diol, 5,5′-dimethyl-3,3 , 3 ′, 3′-tetramethyl-2,3,2 ′, 3′-tetrahydro- (1,1 ′)-spirobiindene-6,6′-dio 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol and 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2, Dihydroxynaphthalene such as 1,6-dihydroxynaphthalene, methyl 3-hydroxy-naphthalene-2-carboxylate, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, trisphenol, dicyclopentadiene, tetrahydroindene, 4- Novolac resins such as vinylcyclohexene, norbornadiene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene, polyhydroxystyrene, polystyrene, polyvinylnaphthalene, poly Examples thereof include vinyl anthracene, polyvinyl carbazole, polyindene, polyacenaphthylene, polynorbornene, polycyclodecene, polytetracyclododecene, polynortricyclene, poly (meth) acrylate, and copolymers thereof.
The blending amount of the blending polymer is 0 to 1000 parts by weight, preferably 0 to 500 parts by weight with respect to 100 parts by weight of the compounds represented by the general formulas (1) to (3).

  One of the performance requirements for the resist underlayer film including the antireflection film is that there is no intermixing with the upper layer film, for example, the silicon-containing resist intermediate layer film and the resist upper layer film, and diffusion of low molecular components into the upper layer film. (Proc. SPIE Vol. 2195, p225-229 (1994)). In order to prevent these problems, a method is generally employed in which thermal crosslinking is performed by baking after spin coating of the antireflection film. Therefore, when a crosslinking agent is added as a component of the antireflection film material, a method of introducing a crosslinkable substituent into the polymer may be employed. Even when a crosslinking agent is not particularly added, it can be crosslinked by a condensation reaction or a radical coupling reaction of a hydroxy group by heating at 300 ° C. or higher. Even if the cross-linking reaction does not particularly occur, mixing is difficult to occur due to the film density being improved by high-temperature baking.

  As the crosslinking agent as the component (D) that can be used in the present invention, specifically, materials described in paragraphs (0056) to (0059) of JP-A-2007-199653 can be added. .

  The blending amount of the crosslinking agent in the present invention is preferably from 3 to 50 parts, particularly preferably from 5 to 40 parts, based on 100 parts (parts by mass, hereinafter the same) of the base polymer (total resin). If it is less than 3 parts, it may cause mixing with the resist, and if it exceeds 50 parts, the antireflection effect may be reduced, or the film after crosslinking may be cracked or the etching resistance may be reduced due to a decrease in carbon density. .

In the present invention, an acid generator can be added as a component (E) for further promoting the crosslinking reaction by heat. There are acid generators that generate an acid by thermal decomposition and those that generate an acid by light irradiation, and any of them can be added.
Specific examples of the acid generator usable in the present invention include those described in paragraphs (0062) to (0084) of JP-A-2007-199653.

In addition, the said acid generator can be used individually by 1 type or in combination of 2 or more types.
The addition amount of the acid generator is preferably 0.1 to 50 parts, more preferably 0.5 to 40 parts with respect to 100 parts of the base polymer. If the amount is less than 0.1 part, the amount of acid generated is small and the crosslinking reaction may be insufficient. If the amount exceeds 50 parts, a mixing phenomenon may occur due to the acid moving to the upper resist.

Furthermore, the resist underlayer film material of the present invention can be blended with a basic compound for improving storage stability.
As a basic compound, it plays the role of the quencher with respect to an acid in order to prevent the acid which generate | occur | produced in trace amount from the acid generator to advance a crosslinking reaction.
As such a basic compound, specifically, those described in paragraphs (0086) to (0089) of JP-A-2007-199653 can be blended.

  The compounding amount of the basic compound is suitably 0.001 to 2 parts, particularly 0.01 to 1 part, based on 100 parts of the total base polymer. When the blending amount is less than 0.001 part, there is no blending effect, and when it exceeds 2 parts, all of the acid generated by heat may be trapped and crosslinking may not occur.

  The organic solvent as the component (B) that can be used in the resist underlayer film material of the present invention is not particularly limited as long as the base polymer, the acid generator, the crosslinking agent, other additives and the like can be dissolved. Specific examples thereof include ketones such as cyclohexanone and methyl-2-amyl ketone; 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol and the like. Alcohols: ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, lactic acid Ethyl, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate , Tert-butyl acetate, tert-butyl propionate, propylene glycol monomethyl ether acetate, propylene glycol mono tert-butyl ether acetate and the like, and one or more of these can be used in combination. It is not limited. In the present invention, among these organic solvents, diethylene glycol dimethyl ether, 1-ethoxy-2-propanol, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether and a mixed solvent thereof are preferably used.

  The blending amount of the solvent is preferably 200 to 10,000 parts, particularly preferably 300 to 5,000 parts with respect to 100 parts of the total base polymer.

In addition to the above components, other components such as a surfactant, a dissolution inhibitor, a carboxylic acid compound, and an acetylene alcohol derivative can be added to the resist underlayer film material of the present invention. The amount may be a normal amount within a range not impeding the effects of the present invention.
As such optional components, specifically, those described in paragraphs (0165) to (0192) of JP-A-2008-111103 can be added.

  The present invention is also a method for forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate using the resist underlayer film material of the present invention, and a photo resist is formed on the resist underlayer film. Forming a resist upper layer film using a resist upper layer film material made of a resist composition, exposing a pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film, Etching the resist underlayer film using the obtained resist pattern as an etching mask, and etching the substrate using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate. provide.

  In this case, the resist upper layer material made of the photoresist composition contains a polymer containing silicon atoms, and etching of the resist lower layer film using the resist upper layer film as a mask is performed mainly using oxygen gas or hydrogen gas. It is preferable to use gas.

  Furthermore, the present invention is a method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate using the resist underlayer film material of the present invention, and silicon is formed on the resist underlayer film. A resist intermediate layer film is formed using a resist intermediate layer film material containing atoms, a resist upper layer film is formed on the resist intermediate layer film using a resist upper layer film material made of a photoresist composition, After exposing the pattern circuit area of the resist upper layer film, developing with a developing solution to form a resist pattern on the resist upper layer film, and etching the resist intermediate layer film using the obtained resist pattern as an etching mask The resist underlayer film obtained by etching the resist underlayer film using the resist intermediate layer film pattern as an etching mask was obtained. The substrate and the on to the mask is etched to provide a pattern forming method comprising forming a pattern on a substrate.

  In this case, the resist upper layer film material made of the photoresist composition does not contain a polymer containing silicon atoms, and etching of the resist lower layer film, which is performed using the intermediate layer film as a mask, mainly comprises oxygen gas or hydrogen gas. It is preferable to use an etching gas.

  Furthermore, the present invention is a method of forming a pattern on a substrate by lithography, wherein at least a resist underlayer film is formed on the substrate using the resist underlayer film material of the present invention, and silicon is formed on the resist underlayer film. An inorganic hard mask intermediate film selected from an oxide film, a silicon nitride film, and a silicon oxynitride film is formed, an organic antireflection film is formed on the inorganic hard mask intermediate film, and the organic antireflection film is formed on the organic antireflection film. After forming a resist upper layer film using a resist upper layer film material made of a photoresist composition, exposing a pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film The organic antireflection film and the inorganic hard mask intermediate film are etched using the obtained resist pattern as an etching mask, and the resulting inorganic hard mask is obtained. A pattern forming method comprising: etching the resist underlayer film using an intermediate layer film pattern as an etching mask; and etching the substrate using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate. provide.

  In this case, the inorganic hard mask intermediate film is preferably formed by a CVD method or an ALD method. In addition, the resist upper layer film material made of the photoresist composition does not contain a polymer containing silicon atoms, and etching of the resist lower layer film using the intermediate layer film as a mask is mainly oxygen gas or hydrogen gas. It is preferable to use an etching gas.

The resist underlayer film formed by using the resist underlayer film material of the present invention can be formed on a substrate to be processed by a spin coat method or the like in the same manner as a normal photoresist film forming method. Good embedding characteristics can be obtained by using a spin coating method or the like. After spin coating, it is desirable to bake to accelerate the crosslinking reaction in order to evaporate the solvent and prevent mixing with the resist upper layer film and resist intermediate layer film. The baking temperature is preferably in the range of 80 to 500 ° C, preferably in the range of 150 to 400 ° C, and in the range of 10 to 300 seconds.
In order to perform crosslinking at a temperature of 250 ° C. or lower, it is preferable to add a thermal acid generator and a crosslinking agent that is crosslinked with an acid. When baking at a high temperature of 250 ° C. or higher, a crosslinking agent is not particularly required, and a dense film having a high carbon density can be formed by high-temperature baking. When baking is performed at such a high temperature, oxygen may be taken into the film by an oxidation reaction and etching resistance may be reduced. In order to prevent an oxidation reaction during baking, it is effective to substitute with an inert gas such as nitrogen, helium, or argon.

Although the thickness of the resist underlayer film is appropriately selected, it is preferably 30 to 20,000 nm, particularly 50 to 15,000 nm. After producing the resist underlayer film, a silicon-containing resist upper layer film is formed thereon in the case of a two-layer process, and a silicon-containing resist intermediate layer film is formed thereon in the case of a three-layer process, and further a resist upper layer film not containing silicon is formed thereon. A (single layer resist film) can be formed.
In this case, a well-known thing can be used as a photoresist composition for forming a resist upper layer film.

  As a photoresist composition containing a silicon-containing polymer in a two-layer process, from the point of resistance to oxygen gas etching, a silicon atom-containing polymer such as a polysilsesquioxane derivative or a vinylsilane derivative is used as a base polymer, and an organic solvent, A positive photoresist composition containing an acid generator and, if necessary, a basic compound is used. In addition, as a silicon atom containing polymer, the well-known polymer used for this kind of photoresist composition can be used.

As the silicon-containing resist interlayer film for the three-layer process, a polysilsesquioxane-based interlayer film is preferably used. Specifically, JP-A-2004-310019, 2005-15779, 2005-18054, 2005-352104, 2007-65161, 2007-163846, 2007. The material containing the silsesquioxane base silicon compound shown by -226170 gazette, 2007-226204 gazette, etc. is mentioned.
By providing the resist intermediate layer film with an effect as an antireflection film, reflection can be more effectively suppressed.

  Especially for 193 nm exposure, if a material with many aromatic groups and high substrate etching resistance is used as the resist underlayer film, the k value increases and the substrate reflection increases, but the substrate reflection is suppressed by suppressing the reflection in the intermediate layer. Can be made 0.5% or less.

  As the resist intermediate layer film having an antireflection effect, an anthracene is used for exposure at 248 nm and 157 nm, a light-absorbing group having a phenyl group or a silicon-silicon bond is pendant for exposure at 193 nm, and a polysilsesquide that is crosslinked by acid or heat. Oxane is preferably used.

  When an inorganic hard mask intermediate layer film is formed on the resist underlayer film, a silicon oxide film, a silicon nitride film, and a silicon oxynitride film (SiON film) are formed by CVD, ALD, or the like. A method for forming a nitride film is described in Japanese Patent Application Laid-Open No. 2002-334869 and WO 2004/066377. The film thickness of the inorganic hard mask is 5 to 200 nm, preferably 10 to 100 nm. Among them, a SiON film having a high effect as an antireflection film is most preferably used. Since the substrate temperature when forming the SiON film is 300 to 500 ° C., it is necessary to withstand a high temperature of 300 to 500 ° C. as the resist underlayer film. Since the resist underlayer film material of the present invention has high heat resistance and can withstand high temperatures of 300 to 500 ° C., it is formed by an inorganic hard mask formed by a CVD method or an ALD method and a spin coating method. Combination with the resist underlayer film thus formed is possible.

  A photoresist film may be formed as a resist upper layer film on such a resist intermediate layer film. However, an organic antireflection film (BARC) is formed on the resist intermediate layer film by spin coating, and then the resist film is formed thereon. Alternatively, a photoresist film may be formed. When a SiON film is used as the resist intermediate layer film, the reflection can be suppressed even in immersion exposure with a high NA exceeding 1.0 by the SiON film and the BARC two-layer antireflection film. Another advantage of forming the BARC is that it has the effect of reducing the tailing of the photoresist pattern immediately above the SiON film.

  The photoresist composition that does not contain a silicon atom-containing polymer in the three-layer process may be either a positive type or a negative type, and the same photoresist composition as that normally used can be used. Those in which the resist upper layer film of the three-layer resist film does not contain a silicon atom-containing polymer has an advantage that the resolution is excellent as compared with a film containing a silicon atom-containing polymer.

In the two-layer and three-layer processes, when the resist upper layer film is formed from the photoresist composition, a spin coating method is preferably used as in the case of forming the resist lower layer film. Pre-baking is performed after spin-coating the resist composition, and a range of 10 to 300 seconds at 80 to 180 ° C. is preferable. Thereafter, exposure is performed according to a conventional method, post-exposure baking (PEB), and development is performed to obtain a resist pattern. The thickness of the resist film is not particularly limited, but is preferably 30 to 500 nm, particularly 50 to 400 nm.
Examples of the exposure light include high energy rays having a wavelength of 300 nm or less, specifically, excimer lasers of 248 nm, 193 nm, and 157 nm, soft X-rays of 3 to 20 nm, electron beams, and X-rays.

Next, etching is performed using the obtained resist pattern as a mask.
Etching of the resist underlayer film in the two-layer process is performed using an etching gas mainly composed of oxygen gas or hydrogen gas. In this case, in addition to oxygen gas or hydrogen gas, it is also possible to add an inert gas such as He, Ar, CO, CO ₂ , NH ₃ , SO ₂ , N ₂ , NO _2, H ₂ gas, Etching can be performed only with CO, CO ₂ , NH ₃ , SO ₂ , N ₂ , and NO ₂ gas without using oxygen gas or hydrogen gas. In particular, the latter gas is used for side wall protection for preventing undercut of the pattern side wall.
The etching of the resist intermediate layer film in the three-layer process is performed by processing the intermediate layer using a fluorocarbon gas with the resist pattern as a mask. Next, the oxygen gas or hydrogen gas etching is performed, and the resist underlayer film is processed using the resist intermediate layer film pattern as a mask.

Etching of the next substrate to be processed can also be performed by a conventional method. For example, if the substrate has SiO ₂ , SiN, a silica-based low dielectric constant insulating film, etching mainly using Freon-based gas, p-Si Etching mainly with chlorine-based or bromine-based gases is used for Al and W. When the substrate processing is etched with chlorofluorocarbon gas, the silicon-containing resist in the two-layer resist process and the silicon-containing intermediate layer in the three-layer process are peeled off simultaneously with the substrate processing. When the substrate is etched with a chlorine-based or bromine-based gas, the silicon-containing resist or the silicon-containing intermediate layer needs to be removed by dry etching using a chlorofluorocarbon-based gas after the substrate is processed.

The resist underlayer film formed using the resist underlayer film material of the present invention is characterized by excellent etching resistance of these substrates to be processed.
Note that the substrate to be processed may be a substrate in which a film to be processed is formed. The substrate is not particularly limited, and a substrate made of a material different from the film to be processed, such as Si, α-Si, p-Si, SiO ₂ , SiN, SiON, W, TiN, and Al, is used. Various low-k films such as Si, SiO ₂ , SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, Al-Si, and their stopper films are used as the work film. Usually, it can be formed to a thickness of 50 to 10,000 nm, particularly 100 to 5,000 nm.

An example of the two-layer process will be described more specifically with reference to FIG.
In the case of a two-layer resist processing process, as shown in FIG. 6A, a resist underlayer film 3 is formed on a film to be processed 2 stacked on a substrate 1 using a resist underlayer film material. A resist upper layer film 4 is formed using a photoresist composition, in particular, a resist upper layer film material made of a photoresist composition based on a silicon atom-containing polymer, and then a pattern circuit of the resist upper layer film 4 through a photomask. The region 5 is exposed (FIG. 6B), and PEB and development are performed to form a resist pattern 4a (FIG. 6C).
Thereafter, using the obtained resist pattern 4a as a mask, the resist underlayer film 3 is subjected to oxygen plasma etching to form a resist underlayer film pattern 3a (FIG. 6D), and after further removing the resist pattern 4a, the resist underlayer film The film 2 to be processed is etched using the pattern 3a as a mask to form the pattern 2a on the substrate 1 (FIG. 6E).

An example of the three-layer process is more specifically shown as follows using FIG.
In the case of the three-layer resist processing process, as shown in FIG. 7A, the resist underlayer film 3 is formed on the processing film 2 laminated on the substrate 1 as in the case of the two-layer resist processing process. Thereafter, a silicon-containing resist intermediate layer film 6 is formed, and a single-layer resist upper layer film 7 is formed thereon.
Next, as shown in FIG. 7B, the pattern circuit region 8 of the resist upper layer film 7 is exposed and subjected to PEB and development to form a resist pattern 7a (FIG. 7C). Using resist pattern 7a as a mask, resist intermediate layer film 6 is etched using CF-based gas to form resist intermediate layer film pattern 6a (FIG. 7D). After removing the resist pattern 7a, the resist underlayer film 3 is subjected to oxygen plasma etching using the obtained resist intermediate layer film pattern 6a as a mask to form a resist underlayer film pattern 3a (FIG. 7E). Further, after removing the resist intermediate layer film pattern 6a, the processed film 2 is etched using the obtained resist underlayer film pattern 3a as a mask to form a pattern 2a on the substrate 1 (FIG. 7F).
When an inorganic hard mask intermediate film is used, the resist intermediate layer film 6 is an inorganic hard mask intermediate layer film. When BARC is laid, a BARC is provided between the resist intermediate layer film 6 and the resist upper layer film 7. The BARC etching may be performed continuously prior to the etching of the resist intermediate layer film 6 or the resist intermediate layer film 6 may be etched by changing the etching apparatus after performing the etching of only the BARC. it can.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited by these description.
In addition, the measuring method of molecular weight was specifically performed by the following method.
The polystyrene equivalent weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC), and the degree of dispersion (Mw / Mn) was determined.

[Synthesis Example 1]
In a 3 L flask, 33 g of 4,4 ′-(9-fluorenylidene) diphenol, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, 1 L of water was added to the reaction solution, and iron trichloride was separated by filtration. The filtrate was concentrated to evaporate dichloroethane to obtain polymer 1.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw2,100, Mw / Mn2.10

[Synthesis Example 2]
In a 3 L flask, 36 g of 4,4′-methoxy- (9-fluorenylidene) diphenyl, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, 1 L of water was added to the reaction solution, and iron trichloride was separated by filtration. The filtrate was concentrated to evaporate dichloroethane to obtain polymer 2.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw2,900, Mw / Mn2.36

[Synthesis Example 3]
In a 3 L flask, 41 g of 4,4'-acetoxy- (9-fluorenylidene) diphenyl, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, 1 L of water was added to the reaction solution, and iron trichloride was separated by filtration. The filtrate was concentrated to evaporate dichloroethane to obtain polymer 3.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw 3,200, Mw / Mn 3.90

[Synthesis Example 4]
In a 3 L flask, 42 g of 6,6 ′-(9-fluorenylidene) 2,2′-dinaphthol, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, and 1 L of water was added to the reaction solution to add iron trichloride. The filtrate was concentrated and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 4.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw1,900, Mw / Mn2.86

[Synthesis Example 5]
In a 3 L flask, 21 g of 6,6 ′-(9-fluorenylidene) 2,2′-dinaphthol, 7.8 g of fluorene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, and 1 L of water was added to the reaction solution. Then, iron trichloride was separated by filtration, and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 5.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw 3,300, Mw / Mn 3.10.

[Synthesis Example 6]
In a 3 L flask, 10.5 g of methyl fluorene 9-carboxylate, 7.8 g of fluorene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred for 100 hours at room temperature, 1 L of water was added to the reaction solution, and iron trichloride was filtered. Fractionation, the filtrate was concentrated and dichloroethane was evaporated to obtain polymer 6.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw 3,500, Mw / Mn 2.66

[Synthesis Example 7]
Stir 13.2 g of methyl fluorene 9,9'-dicarboxylate, 10.6 g of benzo [c] fluorene, 46 g of iron trichloride, 1600 g of dichloroethane at room temperature for 100 hours in a 3 L flask, and add 1 L of water to the reaction solution. Then, iron trichloride was separated by filtration, and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 7.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw1,600, Mw / Mn1.94

[Synthesis Example 8]
In a 3 L flask, 8.6 g of 9-hydroxyfluorene, 7.8 g of fluorene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, 1 L of water was added to the reaction solution, and iron trichloride was separated by filtration. The filtrate was concentrated to evaporate dichloroethane to obtain polymer 8.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw 4,500, Mw / Mn 1.98

[Synthesis Example 9]
In a 3 L flask, 14.5 g of 9- (2-naphthyl) -9-fluorenol, 10.6 g of benzo [b] fluorene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, and 1 L of water was added to the reaction solution. Was added, and iron trichloride was separated by filtration, and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 9.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw1,800, Mw / Mn2.30

[Synthesis Example 10]
37.9 g of 3,3′-divinyl-4,4 ′-(9-fluorenylidene) diphenol, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours in a 3 L flask, and 1 L of water was added to the reaction solution. Then, the iron trichloride was separated by filtration, the filtrate was concentrated, and dichloroethane was evaporated to obtain a polymer 10.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw1,500, Mw / Mn2.10

[Synthesis Example 11]
In a 3 L flask, 21.2 g of 6,6 ′-(9-fluorenylidene) 2,2′-dinaphthol, 10.1 g of 99-diethynyl-fluorene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours and reacted. 1 L of water was added to the liquid, and iron trichloride was separated by filtration, and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 11.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw2,900, Mw / Mn2.63

[Synthesis Example 12]
Stir in a 3 L flask with 21.2 g of 6,6 ′-(9-fluorenylidene) 2,2′-dinaphthol, 12.0 g of 9-benzylidenefluorene, 46 g of iron trichloride, 1600 g of dichloroethane at room temperature for 100 hours. 1 L of water was added to the solution, and iron trichloride was separated by filtration. The filtrate was concentrated to evaporate dichloroethane to obtain polymer 12.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw 3,500, Mw / Mn 3.10

[Synthesis Example 13]
In a 3 L flask, 21.2 g of 6,6 ′-(9-fluorenylidene) 2,2′-dinaphthol, 10 g of fluoranthene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours, and 1 L of water was added to the reaction solution. Then, iron trichloride was separated by filtration, and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 13.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw1,100, Mw / Mn2.30

[Synthesis Example 14]
In a 3 L flask, 21.2 g of 6,6 ′-(9-fluorenylidene) 2,2′-dinaphthol, 10 g of cyclopenta [d, e, f] phenanthrene, 46 g of iron trichloride, 1600 g of dichloroethane were stirred at room temperature for 100 hours. Then, 1 L of water was added to the reaction solution, and iron trichloride was separated by filtration, and the filtrate was concentrated to evaporate dichloroethane to obtain polymer 14.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw 1,200, Mw / Mn 2.90

[Synthesis Example 15]
20 g of polymer 1 obtained in Synthesis Example 1, 7.5 g of 37% formalin aqueous solution, and 0.5 g of oxalic acid were added to a 300 ml flask and stirred at 100 ° C. for 24 hours while stirring. After the reaction, it was dissolved in 500 ml of methyl isobutyl ketone, the catalyst and metal impurities were removed by washing with sufficient water, the solvent was removed under reduced pressure, the pressure was reduced to 150 ° C. and 2 mmHg, and water and unreacted monomers were removed to obtain polymer 15.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw5,900, Mw / Mn4.50

[Synthesis Example 16]
In a 500 mL flask, 12.5 g of Polymer 1 obtained in Synthesis Example 1 and 30 g of epichlorohydrin were placed and dissolved, heated to 80 ° C., and 22 g of 20% sodium hydroxide was added dropwise over 3 hours while stirring. After aging and stirring for a period of time, the lower-layer saline solution was separated, unreacted epiocthydrin was distilled off by heating at 150 ° C., 30 g of MIBK (methyl isobutyl ketone) was added and dissolved, and then washed with water three times. By repeatedly removing the lower aqueous layer, drying filtration, and heating at 150 ° C., MIBK was removed to obtain polymer 16.
The molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the ratio in the polymer was determined by ¹ H-NMR analysis as follows.
Mw2,300, Mw / Mn2.30

  As the polymer 1 for comparative example, 4-hydroxystyrene: 2-methacrylic acid-1-anthracenemethyl = 56: 44 obtained by radical polymerization, weight average molecular weight (Mw) = 14400, molecular weight distribution (Mw / Mn) = 1 .77, Mw 8,800 and Mw / Mn4.5 m-cresol novolak resin as the polymer 2 for comparative example, and polyhydroxystyrene with Mw 9,200 and Mw / Mn 1.05 as the polymer 3 for comparative example were used.

As blend polymer 1, acenaphthylene-hydroxystyrene obtained by cationic polymerization, as blend polymer 2, 4,4 ′-(9H-fluorene-9-ylidene) bisphenol novolakized in formalin, blend polymer 3 As a blend polymer 4, a resin obtained by novolakization of 2,2 ′-(9H-fluorene-9-ylidene) -6,6′-bisnaphthol with formalin, 1-naphthol and dicyclopentadiene co-condensation resin Using.
The structure of the blend polymer and the polymerization ratio molecular weight are shown below.

Moreover, the following were used as a polymer for ArF silicon containing intermediate | middle layer films.

(Examples 1-20, Comparative Examples 1-4)
(Preparation of resist underlayer film material and resist intermediate layer film material)
As shown in Table 1, polymers 1 to 16, comparative polymers 1 to 4, blend polymers 1 to 4, an ArF silicon-containing intermediate layer film polymer, a crosslinking agent, and an acid generator were added to a fluorosurfactant FC-4430 ( Resist underlayer film materials (Examples 1 to 20, Comparative Examples 1 to 4) by dissolving in a solvent containing 0.1% by mass of Sumitomo 3M Co., Ltd.) and filtering with a 0.1 μm fluororesin filter. And a resist interlayer film material (SOG-1).

(Refractive index measurement)
The resist underlayer film materials (Examples 1 to 20 and Comparative Examples 1 to 4) prepared as described above were applied on a silicon substrate, and Examples 16 and Comparative Examples 1 to 3 were baked at 200 ° C. for 60 seconds. Examples 1 to 15, 17 to 20, and Comparative Example 4 were baked at 350 ° C. for 60 seconds to form a resist underlayer film having a thickness of 300 nm. Further, the resist intermediate layer material (SOG1) prepared as described above was applied by spin coating, and baked at 200 ° C. for 60 seconds to form a silicon-containing resist intermediate layer film having a thickness of 30 nm.
After forming the resist underlayer film and the silicon-containing resist intermediate layer film, A. The refractive index (n, k) at a wavelength of 193 nm was obtained using a spectroscopic ellipsometer (VASE) with variable incident angle from Woollam, and the results are shown in Table 1.

ＰＧＭＥＡ；プロピレングリコールモノメチルエーテルアセテート
ＣＲ１（下記構造式参照）
ＡＧ１（下記構造式参照）

PGMEA; propylene glycol monomethyl ether acetate CR1 (see the structural formula below)
AG1 (See the structural formula below)

(Etching test with CF ₄ / CHF ₃ gas)
Next, a dry etching resistance test was performed. First, the same resist underlayer films (Examples 1 to 20 and Comparative Examples 1 to 4) used for the refractive index measurement were prepared, and these resist underlayer films were etched with a CF ₄ / CHF ₃ gas. The test was performed under the following conditions (1). In this case, the thickness difference of the resist underlayer film before and after etching was measured using a dry etching apparatus TE-8500P manufactured by Tokyo Electron Limited. The results are shown in Table 2.

(1) Etching test with CF ₄ / CHF ₃ gas Etching conditions are as shown below.
Chamber pressure 40.0Pa
RF power 1,300W
Gap 9mm
CHF ₃ gas flow rate 30ml / min
CF ₄ gas flow rate 30ml / min
Ar gas flow rate 100ml / min
60 sec

(Preparation of resist upper layer film material)
As a resist upper layer film material, a resin, an acid generator, and a base compound having the composition shown in Table 3 are dissolved in a solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M Ltd.), and 0.1 μm It was prepared by filtering with a fluororesin filter.

In Table 3, the following were used for ArF single layer resist polymer 1, PAG1, Quencher 1, and water repellent polymer 1.

(Pattern etching test)
The prepared resist underlayer film materials (Examples 1 to 20, Comparative Examples 1 to 4) were applied on a 200 nm thick SiO ₂ substrate, and Examples 1 to 15, 17 to 20, and Comparative Example 4 were 350. Example 16 and Comparative Examples 1 to 3 were baked at 200 ° C. for 60 seconds at 60 ° C. to form a resist underlayer film having a thickness of 200 nm.
The adjusted silicon-containing resist intermediate layer film material (SOG1) was applied thereon, and baked at 200 ° C. for 60 seconds to form an intermediate layer having a thickness of 30 nm.
Further, the adjusted resist upper layer film material (ArF SL resist) was applied thereon, and baked at 110 ° C. for 60 seconds to form a resist upper layer film having a thickness of 100 nm.
In this way, a three-layer resist film was obtained.
The lower layer film was baked in a nitrogen stream.

  Next, the pattern circuit area of the resist upper layer film is subjected to ArF immersion exposure equipment (manufactured by Nikon Corporation; NSR-S610C, NA1.30, σ0.98 / 0.65, 35 degree dipole polarized illumination, 6% halftone phase shift) Exposure with a mask), baking (PEB) at 100 ° C. for 60 seconds, and development with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds to obtain a 43 nm 1: 1 positive line and space pattern. It was.

Next, the silicon-containing resist intermediate layer film (SOG) is etched by using the resist pattern obtained by the dry etching as a mask using an etching apparatus Telius manufactured by Tokyo Electron, and the silicon-containing resist intermediate layer film pattern obtained thereby is obtained. As a mask, the resist underlayer film was etched, and the resulting resist underlayer film pattern was used as a mask to etch the SiO ₂ film. Etching conditions are as shown below.
Transfer conditions of resist pattern to resist interlayer film.
Chamber pressure 10.0Pa
RF power 1,500W
CF ₄ gas flow rate 15sccm
O ₂ gas flow rate 75sccm
Time 15sec

Transfer conditions of resist interlayer film pattern to resist underlayer film.
Chamber pressure 2.0Pa
RF power 500W
Ar gas flow rate 75sccm
O ₂ gas flow rate 45sccm
Time 120sec

Transfer conditions of resist underlayer film pattern to SiO ₂ film.
Chamber pressure 2.0Pa
RF power 2,200W
C ₅ F ₁₂ gas flow rate 20 sccm
C ₂ F ₆ gas flow rate 10 sccm
Ar gas flow rate 300sccm
O ₂ 60 sccm
90 seconds

  The cross sections of the patterns were observed with an electron microscope (S-4700) manufactured by Hitachi, Ltd., and the shapes were compared and summarized in Table 4.

  As shown in Table 1, the resist underlayer films formed using the resist underlayer film material of the present invention (Examples 1 to 20) have a refractive index n value of 1.35 to 1.50 at a wavelength of 193 nm. Since the k value is in the range of 0.38 to 0.62, it was confirmed that it had a refractive index suitable for practical use as a resist underlayer film in a multilayer process for immersion lithography.

Further, as shown in Table 2, it was confirmed that the CF ₄ / CHF ₃ gas etching rate of Examples 1 to 20 was sufficiently slower than Comparative Examples 1 to 3 and slower than Comparative Example 4.

Furthermore, as shown in Table 4, even when the resist underlayer film is heat-treated at a high temperature of 350 ° C., the resist shape after development, the shape of the resist underlayer film after oxygen etching, and the substrate processing etching are good. It was confirmed that there was no distortion of the pattern (Examples 1 to 15 and 17 to 20). Moreover, also in Example 16 which heat-processed below 300 degreeC (this example 200 degreeC) like the past, the result favorable as Examples 1-15 and 17-20 was obtained.
On the other hand, in the comparative example, when the heat treatment was performed at 350 ° C. (Comparative Example 4) and when the heat treatment was performed at 200 ° C. (Comparative Examples 1 to 3), film loss and pattern variation occurred It was recognized that

  As described above, if the resist underlayer film material of the present invention is used, the reflectance can be reduced, and a resist underlayer film having high etching resistance can be formed.In addition, by using the resist underlayer film material of the present invention, It was confirmed that a highly accurate pattern can be formed on the substrate.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Processed film, 2a ... Pattern formed in substrate, 3 ... Resist lower layer film, 3a ... Resist lower layer film pattern, 4, 7 ... Resist upper layer film, 4a, 7a ... Resist upper layer film pattern, 5 , 8 ... pattern circuit region, 6 ... resist intermediate layer film, 6a ... resist intermediate layer film pattern.

Claims (11)

A resist underlayer film material for a multilayer resist film used in lithography, which contains at least polyfluorene having a repeating unit a1 represented by the following general formula (1).

(In General Formula (1), R ¹ and R ² are the same or different hydrogen atoms, hydroxyl groups, C 1-6 acyl groups, C 1-6 alkoxy groups, C 1-6 alkoxys. Carbonyl group, carbonyl group, amino group, acid labile group, glycidyl group, linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 20 carbon atoms, 2 to 10 carbon atoms An alkenyl group, an alkynyl group having 2 to 10 carbon atoms, a carboxyl group, or a cyano group, or R ¹ and R ² may be combined into one group. These are an alkylidene group having 6 or an imino group, and these groups are a hydroxyl group, an acyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkoxycarbonyl group having 1 to 6 carbon atoms, and 1 carbon atom. -10 linear, branched Or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, an amino group, a nitro group, a cyano group, an acid labile group, a glycidyl group, One or a plurality of carboxyl groups may be present, R ³ and R ⁴ are each a benzene ring or a naphthalene ring, R ⁵ and R ⁶ are each a hydrogen atom, a straight chain having 1 to 10 carbon atoms, A branched or cyclic alkyl group, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms.) The photoresist underlayer film material according to claim 1, wherein the repeating unit a1 represented by the general formula (1) is a repeating unit a2 represented by the following general formula (2).

(In General Formula (2), R ^{3 to} R ⁶ are the same as described above, R ⁷ and R ⁸ are each a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, and 6 to 10 carbon atoms. An aryl group, an alkenyl group having 2 to 10 carbon atoms, or an alkynyl group having 2 to 10 carbon atoms, m and n are each an integer of 0 to 2, and R ⁹ and R ¹⁰ are a hydrogen atom and a carbon number, respectively. 1-6 linear, branched, and cyclic alkyl groups, C6-C20 aryl groups, C2-C20 alkenyl groups, C2-C10 alkynyl groups, C1-C6 acyls Group or alkoxycarbonyl group, acid labile group, or glycidyl group.) The polyfluorene having the repeating unit a2 represented by the general formula (2) contains a repeating unit a3 represented by the following general formula (3) obtained by novolacizing the repeating unit a2. The resist underlayer film material according to claim 2.

(In the general formula (3), R ^{3 to} R ¹⁰ , m and n are as described above, R ¹¹ is an alkylene group having 1 to 10 carbon atoms, and may have an allyl group.)   The resist underlayer film material according to any one of claims 1 to 3, wherein the resist underlayer film material contains an organic solvent.   The resist underlayer film material according to any one of claims 1 to 4, wherein the resist underlayer film material further contains a crosslinking agent and an acid generator.   A method of forming a pattern on a substrate by lithography, wherein a resist underlayer film is formed on the substrate by using the resist underlayer film material according to any one of claims 1 to 5, and the resist underlayer A resist upper layer film is formed on the film using a resist upper layer film material, and a pattern circuit region of the resist upper layer film is exposed, and then developed with a developing solution to form a resist on the resist upper layer film. Forming a pattern, etching the resist underlayer film using the obtained resist pattern as an etching mask, etching the substrate using the obtained resist underlayer film pattern as an etching mask, and forming a pattern on the substrate Pattern forming method.   Etching of the resist underlayer film, in which the resist upper layer film material made of the photoresist composition includes a polymer containing silicon atoms and is performed using the resist upper layer film as a mask, uses an etching gas mainly composed of oxygen gas or hydrogen gas. The pattern forming method according to claim 6, wherein the pattern forming method is performed.   A method of forming a pattern on a substrate by lithography, wherein a resist underlayer film is formed on the substrate by using the resist underlayer film material according to any one of claims 1 to 5, and the resist underlayer A resist intermediate layer film is formed on the film using a resist intermediate layer film material containing silicon atoms, and a resist upper layer film is formed on the resist intermediate layer film using a resist upper layer film material made of a photoresist composition. After forming and exposing the pattern circuit region of the resist upper layer film, developing with a developer to form a resist pattern on the resist upper layer film, and using the obtained resist pattern as an etching mask, the resist intermediate layer film is formed. The resist underlayer film is etched using the obtained resist intermediate layer film pattern as an etching mask. Pattern forming method and forming a pattern on a substrate by etching the substrate with an underlying film pattern as a mask.   A method of forming a pattern on a substrate by lithography, wherein a resist underlayer film is formed on the substrate by using the resist underlayer film material according to any one of claims 1 to 5, and the resist underlayer An inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film and a silicon oxynitride film is formed on the film, an organic antireflection film is formed on the inorganic hard mask intermediate film, and the organic reflection A resist upper layer film material made of a photoresist composition is formed on the prevention film, and a pattern circuit region of the resist upper layer film is exposed, and then developed with a developer to form the resist upper layer film. A resist pattern was formed, and the obtained resist pattern was used as an etching mask to etch the organic antireflection film and the inorganic hard mask intermediate layer film. The pattern formation is characterized in that the resist underlayer film is etched using the hard mask intermediate layer film pattern as an etching mask, and the substrate is etched using the obtained resist underlayer film pattern as an etching mask to form a pattern on the substrate. Method.   The pattern forming method according to claim 9, wherein the inorganic hard mask intermediate film is formed by a CVD method or an ALD method.   The resist upper layer film material made of the photoresist composition does not contain a polymer containing silicon atoms, and etching of the resist lower layer film using the intermediate layer film as a mask is an etching gas mainly composed of oxygen gas or hydrogen gas. The pattern forming method according to claim 8, wherein the pattern forming method is performed by using the method.

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