JP2013080169A - Method for forming photoresist pattern and method for forming etching mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a uniform side wall portion even when an object structure on which a thin film for forming a side wall portion is deposited is formed from an organic material in a double patterning process.SOLUTION: A method for forming a photoresist pattern includes the steps of: forming a photoresist film on a substrate; exposing the photoresist film to an alkaline chemical agent; exposing the photoresist film which has been exposed to the chemical agent to light; and developing the exposed photoresist film.

Description

  The present invention relates to a developing method for developing a resist film formed and exposed on a substrate, and more particularly to a developing method suitable for using a resist pattern as a core material for forming a thin film in a double patterning process.

  As semiconductor integrated circuits are highly integrated, circuit elements are further miniaturized. For miniaturization, it is preferable to use short-wavelength exposure light such as extreme ultraviolet (EUV) light, but an exposure apparatus that emits such exposure light has not yet been put into practical use.

  Therefore, a double patterning technique that enables miniaturization by a conventional exposure apparatus has been developed and put into practical use.

JP 2007-27742 A US Pat. No. 5,013,680 (columns 9 to 10)

  For double patterning in a broad sense, a predetermined thin film is deposited on, for example, a line-and-space structure formed on a substrate using conventional photolithography technology, and the thin film is deposited on both sides of the line. There is a so-called self-aligned double patterning using a thin film (side wall part). Even if the width of the line formed by the photolithography technique is about the current exposure limit dimension, a side wall portion having a width smaller than the exposure limit dimension can be formed. For example, by adjusting the line and space width of the line and space structure and the thickness of the thin film, a side wall portion having a width that is approximately one half of the line width of the line and space structure can be formed. it can. Further, if a predetermined thin film having a predetermined thickness is further deposited on the side wall portion thus obtained, it has a width of about a quarter of the line width of the original line and space structure. A side wall part can be obtained. As described above, according to the double patterning, it is possible to form a pattern having a dimension smaller than the exposure limit dimension of the photolithography technique.

  Here, the original line and space structure may be formed of an inorganic material such as amorphous carbon. According to this, since it becomes possible to obtain a uniform line width and space width, the side wall portions formed on both side surfaces of the line can also be formed with a uniform width and interval. Therefore, it is advantageous for making the pattern finer than the exposure limit dimension uniform.

  On the other hand, it is conceivable to form the original line and space structure with an organic material such as a photoresist film. An inorganic material such as amorphous carbon is formed by, for example, a chemical vapor deposition (CVD) process, whereas an organic material such as a photoresist film can be formed by a spin coating method, thereby reducing the manufacturing cost of a semiconductor integrated circuit. There is an advantage.

  However, when a line-and-space structure is formed with a photoresist film or the like and a thin film is deposited on the line-and-space structure, the side surface of the line may be inclined or the upper end of the line may be rounded. There is a problem that the uniformity of the pattern is reduced.

  In light of the above circumstances, the present invention is a photoresist pattern capable of forming a uniform sidewall even when a target structure on which a thin film for sidewall formation is deposited is formed of an organic material in a double patterning process. A forming method is provided.

  According to the first aspect of the present invention, a step of forming a photoresist film on a substrate, a step of exposing the photoresist film to an alkaline agent, and a step of exposing the photoresist film exposed to the agent And a method of developing the exposed photoresist film. A method for forming a photoresist pattern is provided.

  According to the second aspect of the present invention, the step of forming the first film and the second film made of different materials in this order on the etching target film formed on the substrate, and the second film A step of forming a photoresist film thereon, a step of exposing the photoresist film to an alkaline agent, a step of exposing the photoresist film exposed to the agent, and developing the exposed photoresist film Forming a first pattern having a predetermined pattern, forming a first core part on which a silicon-containing film can be deposited by reducing the first pattern, and the first pattern Forming a second pattern including the silicon-containing film deposited on the side surface of the first core part by forming a silicon-containing film covering the core part and etching back the silicon-containing film; Etching the second film using the second pattern to form a second core part on which a silicon-containing film can be deposited; and a silicon-containing film covering the second core part. Forming and etching back the silicon-containing film to form a third pattern including the silicon-containing film deposited on the side surface of the second core portion, and using the third pattern Etching the first film to form an etching mask for etching the film to be etched is provided.

  According to an embodiment of the present invention, even when a target structure on which a thin film for sidewall formation is deposited is formed of an organic material in a double patterning process, a photoresist pattern that can form a uniform sidewall is formed. A forming method is provided.

1 is a schematic top view showing a coating and developing apparatus suitable for carrying out an etching mask forming method according to an embodiment of the present invention. It is a schematic side view which shows the coating and developing apparatus of FIG. It is a schematic sectional drawing which shows the deactivation processing apparatus provided in the coating and developing apparatus of FIG. 4 is a flowchart illustrating an etching mask forming method according to an embodiment of the present invention. It is sectional drawing which shows typically the cross section of the wafer W in each process of the etching mask formation method by embodiment of this invention. FIG. 7 is a cross-sectional view schematically showing a cross section of the wafer W in each step of the etching mask forming method according to the embodiment of the invention following FIG. 6. It is explanatory drawing which shows the comparative example for demonstrating the effect and advantage of the etching mask formation method by embodiment of this invention. It is explanatory drawing explaining the effect and advantage of the etching mask formation method by embodiment of this invention. It is explanatory drawing explaining the effect and advantage of the modification of the etching mask formation method by embodiment of this invention.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In all the attached drawings, the same or corresponding members or parts are denoted by the same or corresponding reference numerals, and redundant description is omitted.

With reference to FIG. 1 and FIG. 2, a coating and developing apparatus that can be used when performing an etching mask forming method according to an embodiment of the present invention will be described. FIG. 1 is a plan view of the coating and developing apparatus, and FIG. 2 is a side view of the coating and developing apparatus of FIG.
As shown in FIG. 1, the coating and developing apparatus 30 of this embodiment includes a carrier block B1, a processing block B2, and an interface block B3. The interface block B3 is coupled to the exposure apparatus B4.

  The carrier block B1 takes a wafer 60 from the carrier 60 placed on the carrier 60 and a processing block B2 on which the sealed carrier C that accommodates a plurality of wafers is placed, and transfers the wafer to the processing block B2. And a transfer arm 62 for storing the wafer processed in the processing block B2 in the carrier C.

  As shown in FIG. 2, a DEV layer L1 for performing development processing, a BCT layer L2 for forming an antireflection film as an underlayer of the photoresist film, and a photoresist solution are applied to the processing block B2. A COT layer L3 for forming an antireflection film formed on the photoresist film and a TCT layer L4 for forming an antireflection film are sequentially provided from the bottom.

  In the DEV layer L1, the developing units 68 shown in FIG. 1 are stacked in, for example, two stages, and a transport arm 69a (FIG. 2) for transporting the wafer W to the two-stage developing unit 68 is provided. . In the developing unit 68, one or a plurality of (three in the illustrated example) developing units 68a for developing the exposed photoresist film formed on the wafer W are arranged. Although not shown, the developing unit 68a supplies a developer to the spin chuck that rotatably holds the wafer W on which the exposed photoresist film is formed, and the wafer W held by the spin chuck. A supply nozzle, a rinse nozzle for supplying a rinse solution for washing away the developer, and a cup for receiving the developer and the rinse solution supplied to the wafer W and scattered from the wafer W by the rotation of the spin chuck are provided.

  Although not shown, the BCT layer L2 and the TCT layer L4 are each provided with an antireflection film coating unit that spin-coats a chemical solution for the antireflection film to form an antireflection film. In the coating unit, one or a plurality of antireflection film coating units having the same configuration as the above-described developing unit 68a are arranged.

  Although not shown in the figure, the COT layer L3 is provided with a photoresist film application part that spin-coats a photoresist solution to form a photoresist film, and the photoresist film application part is similar to the developing unit 68a described above. One or a plurality of photoresist film coating units having the following structure are arranged.

  The number of development units arranged in the DEV layer L1, the number of antireflection film coating units arranged in the BCT layer L2 and the TCT layer L4, and the number of photoresist film coating units arranged in the COT layer L3 are as follows: You may adjust suitably. Further, according to circumstances, for example, a processing unit for processing the photoresist film formed on the wafer W in the COT layer L3 with a chemical solution such as HMDS solution may be arranged in the TCT layer L4. This processing unit can have the same configuration as the developing unit and the coating unit, although the chemical solution to be supplied is different.

  In the processing block B2, heating units and cooling units (not shown) provided corresponding to the layers L1 to L4 are stacked on the processing unit group 63 (FIG. 1). For example, a post-application heating (PAB) unit for heating a photoresist film applied on the wafer W so as to face the COT layer L3 is provided, and the heated wafer W is cooled to room temperature (for example, 23 ° C.). A cooling unit is provided to maintain the temperature.

Further, in order to transfer the wafer W between the units, a transfer arm 69b is arranged in the BCT layer L2, and a transfer arm 69d is arranged in the TCT layer L4.
Furthermore, in the processing block B2, a first shelf unit U1 is provided on the carrier block B1 side, and a second shelf unit U2 is provided on the interface block B3 side. The first shelf unit U1 and the second shelf unit U2 are provided with a plurality of delivery units. Among these transfer units, the transfer unit indicated by reference numeral CPL + number in FIG. 2 is provided with a cooling unit for temperature adjustment, and the transfer unit indicated by reference numeral BF + number includes a plurality of wafers W. Is provided. Further, adjacent to the first shelf unit U1 in the X direction (see FIG. 1), there is provided a transfer arm 16 that can be moved up and down to transfer the wafer W between each part of the first shelf unit U1.

  A shuttle arm 700 is provided in the upper part of the DEV layer L1 (see FIG. 2). The shuttle arm 700 can directly transfer the wafer W from the delivery unit CPL110 of the first shelf unit U1 to the delivery unit CPL120 of the second shelf unit U2.

  The interface block B3 includes an interface arm F, and the interface arm F transfers the wafer W between the second shelf unit U2 and the exposure apparatus B4. In the exposure apparatus B4, a predetermined exposure process is performed on the wafer W transferred from the interface arm F. In addition, the deactivation processing apparatus 10 is disposed in the interface block B3, and the loading and unloading of the wafer W with respect to the deactivation processing apparatus 10 is performed by the interface arm F.

  Referring to FIG. 3, the deactivation processing apparatus 10 includes a container main body 202 whose upper end is open, and a lid 203 provided so as to cover the upper opening of the container main body 202. The container main body 202 includes a frame body 221 having a circular top surface shape, a bowl-shaped bottom part 222 extending inward from the bottom part of the frame body 221, and a wafer mounting table 204 supported by the bottom part 222. A heating unit 204 h is provided inside the wafer mounting table 204, whereby the wafer W mounted on the wafer mounting table 204 can be heated.

  On the other hand, the lid 203 covers the container body 202 so that the peripheral edge 231 of the lid 203 approaches the upper surface of the frame 221 of the container body 202, so that the upper end opening of the container body 202 is the lid 203. Closed by A processing chamber 220 is defined between them.

  The wafer mounting table 204 is provided with a plurality of lifting pins 241 for transferring the wafer W to and from an external transfer means (not shown). The lifting pins 241 can be lifted and lowered by a lifting mechanism 242. It is configured. Reference numeral 243 in the figure is a cover body that is provided on the back side of the mounting table 204 and surrounds the periphery of the elevating mechanism 242. The container main body 202 and the lid body 203 are configured to be movable up and down relative to each other. In this example, the lid 203 can be moved up and down between a processing position connected to the container main body 202 and a substrate loading / unloading position located above the container main body 202 by an elevating mechanism (not shown).

In addition, a processing gas supply unit 205 that supplies a deactivation processing gas to the wafer W mounted on the mounting table 204 is provided at the center on the back surface side of the lid 203. In addition, a gas supply path 233 communicating with the processing gas supply unit 205 is formed inside the lid 203. In this example, the gas supply path 233 is bent at the upper side of the lid 3 so as to extend substantially horizontally, and the upstream end of the gas supply path 233 is connected to the deactivation treatment gas via the gas supply pipe 261. A supply source 262 and a replacement gas supply source 263 are connected. In the present embodiment, hexamethyldisilazane (HMDS) gas is used as the deactivation treatment gas. As the replacement gas can be used an inert gas such as rare gas or N ₂ gas.

  As the deactivation processing gas supply source 262, for example, a gas generator such as a bubbler tank or a skimmer tank can be used. For example, when the deactivation treatment gas is HMDS gas, the supply source 262 generates gas (or steam) from the HMDS liquid and supplies the generated gas to the gas supply path 233.

The gas supply pipe 261 is provided with a first flow rate adjustment valve V 1 that adjusts the supply flow rate of the HMDS gas between the supply source 262 of the HMDS gas and the gas supply path 233. In addition, a second flow rate adjustment valve V <b> 2 that adjusts the N ₂ gas supply flow rate is provided between the N ₂ gas supply source 263 and the gas supply path 233. These flow rate adjusting valves V1 and V2 have an opening / closing function in addition to the flow rate adjusting function. When these are opened and closed in a complementary manner, the gas supplied to the gas supply path 233 becomes HMDS gas and N ₂ gas. Be switched between. Further, the supply flow rate of each gas can be adjusted. Further, if the flow rate adjusting valves V 1 and V 2 are opened at the same time, a mixed gas of HMDS gas and N ₂ gas (diluted HMDS gas) can be supplied to the gas supply path 233.

  On the other hand, an exhaust path 281 for exhausting the inside of the processing chamber 220 from the outside of the wafer W on the wafer mounting table 204 is formed in the lid 203. Further, a flat cavity 282 having a ring-like planar shape, for example, is formed in the upper wall portion 232 of the lid 203 in a planar shape in a region other than the central region where the processing gas supply unit 205 is provided. Yes. The downstream end of the exhaust path 281 described above is connected to the cavity 282. Further, a plurality of, for example, six exhaust pipes 283 are connected to the hollow portion 282 in the vicinity of the center of the lid 203, for example. The downstream end of the exhaust pipe 283 is connected to an ejector constituting the exhaust means 284 via an exhaust flow rate adjusting valve V4.

  According to such a configuration, the HMDS gas is supplied from the HMDS gas supply source 262 through the gas supply path 233 and the processing gas supply unit 205 to the wafer W mounted on the wafer mounting table 204, and the exhaust path The air is exhausted from the air outlet 281 through the cavity 282 and the exhaust pipe 283 by the exhaust means 284.

  Next, an example of a method for forming an etching pattern on a wafer using the coating and developing apparatus 30 will be described. First, the wafer W is transferred from the carrier block B1 by the transfer arm 62 to the transfer unit of the first shelf unit U1, for example, the transfer unit CPL2 corresponding to the BCT layer L2. Next, the wafer W is transferred to the transfer unit CPL3 by the transfer arm 16, and is transferred to the COT layer L3 by the transfer arm 69c. In the COT layer L3, the surface (or uppermost layer) of the wafer W is hydrophobized. Next, the film is transferred to the coating unit by the transfer arm 69c, where a photoresist film is formed. Since the surface of the wafer W is hydrophobized, the photoresist film is formed with high adhesion to the surface of the wafer W (or the underlying layer).

  Thereafter, the wafer W is transferred to the delivery unit BF3 of the first shelf unit U1 by the transfer arm 69c. The wafer W transferred to the transfer unit BF3 is transferred to the transfer unit CPL4 by the transfer arm 16, and transferred to the TCT layer L4 by the transfer arm 69d. Then, an antireflection film is formed on the photoresist film of the wafer W in the TCT layer L4, and is transported to the delivery unit TRS4. In the case where the antireflection film is not formed on the photoresist film according to the required specifications or the like, or instead of performing the hydrophobizing process on the wafer W, the antireflection film is directly applied to the wafer W by the BCT layer L2. Sometimes formed.

  The wafer W on which the photoresist film and the antireflection film are formed is transferred from the transfer unit BF3 or TRS4 to the transfer unit CPL110 by the transfer arm 16 (FIG. 1), and transferred to the transfer unit CPL120 by the shuttle arm 700.

  Next, the wafer W is transferred to the deactivation processing apparatus 10 by the interface arm F (FIG. 1) of the interface block B3. In the deactivation processing apparatus 10, deactivation processing described later is performed on the photoresist film formed on the surface of the wafer W. Next, the wafer W is taken out from the deactivation processing apparatus 10 by the interface arm F and transferred to the exposure apparatus B4. Then, after the photoresist film formed on the wafer W is exposed in the exposure apparatus B4, the wafer W is transferred to the delivery unit TRS6 of the second shelf unit U2 by the interface arm F. Subsequently, the wafer W is transferred to the DEV layer L1 by the transfer arm 69a. Here, after the exposed photoresist film is developed, the wafer W is transferred to the transfer unit TRS1 of the first shelf unit U1 by the transfer arm 69a. The carrier arm 62 accommodates the carrier C. Thereby, a photoresist pattern is formed on the wafer W.

  Next, an etching mask forming method according to an embodiment of the present invention will be described with reference to FIGS. This etching mask forming method includes a resist pattern forming method according to an embodiment of the present invention.

First, in step S41 (FIG. 4), the first inorganic material film 12, the second inorganic material film 13, and the inorganic antireflection film 14 are formed in this order on the etching target film 11 formed on the wafer. (See FIG. 5A).
The first inorganic material film 12 is formed of a material that can realize a sufficient etching ratio when the etching target film 11 is etched. In the present embodiment, the first inorganic material film 12 is formed of silicon nitride (SiN) deposited by chemical vapor deposition (CVD) with respect to the etching target film 11 formed of silicon (Si). ing. In other embodiments, for example, a TiN film or a Ti film may be used.

In the present embodiment, the second inorganic material film 13 is formed of spin-on carbon that is formed by spin coating. In another embodiment, for example, the second inorganic material film 13 may be formed of an organic material by a spin coating method.
In the present embodiment, the inorganic antireflection film 14 is formed of amorphous silicon deposited by a CVD method. In another embodiment, the inorganic antireflection film 14 may be formed of Ti, TiO ₂ , TiN, or the like deposited by a method such as vacuum deposition, CVD, or sputtering.

  Next, a wafer having the structure shown in FIG. 5A is carried into the coating and developing apparatus 30 and subjected to a hydrophobizing process and a cooling process. Next, in step S42 (FIG. 4), a photoresist film 15 is formed on the inorganic antireflection film 14 in the coating unit of the COT layer L3 (FIG. 2). The photoresist film 15 is preferably formed of, for example, a chemically amplified resist. The wafer on which the photoresist film 15 is formed is transferred to the deactivation processing apparatus 10 (FIGS. 1 and 3). In the deactivation processing apparatus 10, the wafer W is mounted on the wafer mounting table 204, and the wafer W is heated to a predetermined temperature (for example, 110 ° C. for 60 seconds) by the heating unit 204h, as shown in FIG. Thus, the photoresist film 15 is exposed to the HMDS gas (FIG. 4: step S43). Thereby, a part of the HMDS gas in contact with the surface of the photoresist film 15 condenses on the surface of the photoresist film 15 and remains on the surface layer portion of the photoresist film 15.

  Since the wafer W (photoresist film 15) is heated in the deactivation processing apparatus 10, post-application baking (PAB) of the photoresist film 15 is not necessary in this embodiment.

  Next, the wafer is carried into the exposure apparatus B4, and the photoresist film 15 is exposed using a predetermined photomask (reticle) (FIG. 4: step S44). The exposed wafer is carried into the coating and developing apparatus 30 again from the exposure apparatus B4. After the post-exposure baking, the exposed photoresist film 15 is developed in the developing unit 68 (FIG. 1) of the DEV layer L1. For this development, for example, an aqueous tetramethylammonium hydroxide (TMAH) solution (2.38% by weight) is preferably used. As a result, as shown in FIG. 5C, a first pattern 15a formed of a photoresist is obtained (FIG. 4: step S45). The first pattern 15a is a line-and-space pattern having, for example, a line having a width w1 of 40 nm and a space having a width s1 of 40 nm.

  Subsequently, the wafer on which the first pattern 15a is formed is unloaded from the coating and developing apparatus 30 and loaded into an oxygen plasma processing apparatus (not shown). In the oxygen plasma processing apparatus, when the first pattern 15a is exposed to oxygen plasma, as shown in FIG. 5A, the first pattern 15a is reduced (slimmed) to form a core 15b from the first pattern 15a. (FIG. 4: Step S46). The core 15b has a line having a width w2 of about 20 nm and a space having a width s2 of about 60 nm.

  Next, a silicon oxide film 16 is deposited so as to cover the core 15b in a CVD apparatus (not shown), for example. For this deposition, for example, a molecular layer deposition apparatus is preferably used. The molecular layer deposition enables conformal deposition. Therefore, the deposited silicon oxide film 16 deposited on the side surface of the core 15b and the silicon oxide film deposited on the top surfaces of the core 15b and the inorganic antireflection film 14 are provided. 16 has substantially the same film thickness. This thickness t1 is, for example, about 20 nm.

  Next, when the silicon oxide film 16 is etched back by anisotropic etching in an etching apparatus (not shown), the silicon oxide film 16 deposited on the top surfaces of the core 15b and the inorganic antireflection film 14 is etched, and the core 15b The silicon oxide film 16 deposited on the side surface of the line remains. Next, when the core 15b remaining on the inorganic antireflection film 14 is removed by, for example, oxygen plasma, a second pattern 16a formed of silicon oxide is obtained as shown in FIG. 5F (FIG. 4: Step S47). ). The second pattern 16a has a line having a width w3 of about 20 nm and a space having a width s3 of about 20 nm.

  Subsequently, the inorganic antireflection film 14 and the second inorganic material film 13 are etched again by the etching apparatus using the second pattern 16a as a mask, and the inorganic antireflection film remaining on the second inorganic material film 13 after the etching is etched. If the film | membrane 14 and the 2nd pattern 16a are removed, as shown to Fig.6 (a), the core 13a will be obtained (FIG. 4: step S48). Similar to the second pattern 16a, the core 13a has a line having a width w3 of about 20 nm and a space having a width s3 of about 20 nm.

  Thereafter, in the molecular layer deposition apparatus, a silicon oxide film 17 is deposited so as to cover the core 13a. Here, the thickness t2 of the silicon oxide film 17 is about 10 nm. Subsequently, when the silicon oxide film 17 is etched back by anisotropic etching again in the etching apparatus, the silicon oxide film 17 deposited on the upper surface of the core 13a and the upper surface of the first inorganic material film 12 is etched, and the core The silicon oxide film 17 deposited on the side wall of the line 13a remains. Thereafter, when the core 13a is removed, as shown in FIG. 6I, a third pattern 17a formed of silicon oxide is obtained (FIG. 4: step S49). The third pattern 17a has a line having a width w4 of about 10 nm and a space having a width s4 of about 10 nm.

  Subsequently, when the first inorganic material film 12 is etched using the third pattern 17a as a mask, a fourth pattern 12a formed of SiN is obtained as shown in FIG. 6 (j) (FIG. 4: Step S50). Similar to the third pattern 17a, the fourth pattern 12a includes a line having a width w4 of about 10 nm and a space having a width s4 of about 10 nm. For this reason, when the etching target film 11 is etched using the fourth pattern 12a, the etching target film 11 also has a line-and-space shape. The width of about 10 nm is a quarter of the width w1 of about 40 nm in the first pattern 15a formed of the photoresist shown in FIG. 5C. That is, a line width lower than the resolution in the photolithography technique can be realized.

  Next, effects and advantages of the above-described etching mask forming method will be described with reference to FIG.

  When a photoresist film formed by a chemical doubling type photoresist is exposed, an acid is generated in a portion irradiated with exposure light. The generated acid reacts with the alkali-insoluble protective group in the photoresist, thereby converting the alkali-insoluble protective group into a soluble group. That is, the exposed portion is dissolved in the developer. As shown in FIG. 7A, when the photoresist film 150 is exposed, the exposure light UV is diffracted at the edge of the light shielding portion LB of the photomask PM, and therefore, in the portion 150U below the edge of the light shielding portion LB. Acid is generated, and this portion 150U becomes soluble. For this reason, in the pattern 150a after development, as shown by an arrow Y in FIG. When the pattern 150a having such a shape is slimmed, as shown in FIG. 7C, the upper end portion of the line of the pattern 150b after the slimming also remains rounded. When the silicon oxide film 160 is deposited using this as a core and the pattern 160a is formed by etch back, the width w30 of the space between two adjacent lines in the pattern 160a is narrow, as shown in FIG. The width 31 of the space becomes wide. That is, the space width cannot be made uniform in the pattern 160a.

  However, in the etching mask forming method according to the embodiment of the present invention, the photoresist film 15 is exposed to the HMDS gas, and HMDS remains in the surface layer portion UL of the photoresist film 15 shown in FIG. Therefore, when the photoresist film 15 is exposed, the exposure light UV is diffracted at the edge of the light shielding portion LB of the photomask PM (FIG. 8B), and an acid is generated at a portion indicated by reference numeral 15U in the drawing. Even so, it is neutralized by the remaining HMDS. For this reason, the alkali-insoluble protecting group does not change to a soluble group (deactivated), and this portion 15U remains insoluble. Thereby, the upper end of the developed first pattern 15a is not rounded, and a line having a rectangular cross-sectional shape is formed as shown in FIG. 8C. Therefore, as shown in FIG. 8D, the width of the space can be made uniform in the second pattern 16a formed through slimming and silicon oxide deposition.

  Further, in order to solve the problem described with reference to FIG. 7, it is conceivable that the core for depositing the silicon oxide film 160 is formed of an inorganic material such as amorphous carbon instead of the photoresist. However, in this case, it is necessary to deposit the inorganic material film by, for example, a CVD method, and thus there is a disadvantage that the process cost becomes high.

Next, a modification of the etching mask forming method according to the embodiment of the present invention will be described.
(Modification 1)
When the exposed photoresist film 15 is developed to form the first pattern 15a (FIG. 5C), the side walls of the first pattern 15a are inclined as shown in FIG. 9A. May end up. In this case, the core 15b formed by slimming the first pattern 15a also has a cross-sectional shape with inclined side surfaces. Therefore, the second pattern 16a formed through the deposition of the silicon oxide film 16 (FIG. 5E) and the etch back (FIG. 5F) is inclined with respect to the underlying layer. This may cause a problem that the space width of the second pattern 16a is not uniform.

  It is considered that the inclination of the side surface of the first pattern 15a is caused by so-called scum. In general, the scum is generated because a portion of the photoresist film that is not sufficiently developed is dissolved in the developer but not sufficiently dissolved to flow out together with the developer. Moreover, since it remains in the lower part of the side wall of the photoresist pattern, the pattern side wall appears to be inclined.

  In the first modification, a developer whose temperature has been raised in the developing process of the photoresist film 15 is used. The temperature of the developer is higher than room temperature (for example, 23 ° C.) and may be in a range up to about 100 ° C., for example. More preferably, it is the range from 23 degreeC to 70 degreeC. Further, the temperature of the developer can be raised by providing a heating unit (none of which is not shown) in the middle of the path from the developer storage unit to the developer application nozzle in the developing unit, for example. The heating unit can be constituted by a predetermined container (not shown) and a heater (not shown) for heating the container. Moreover, it is preferable to provide a tape heater for heating the pipe between the heating unit and the developer supply nozzle to heat the pipe.

  By using the developer whose temperature has been increased, the portion of the photoresist film 15a that has not been sufficiently exposed can be dissolved, and thus the scum can be removed. As shown in FIG. A first pattern 15a having a shape is formed.

(Modification 2)
In the second modification, a high concentration developer is used in the developing process of the photoresist film 15. As described above, a 2.38 wt% TMAH aqueous solution can be used as described above, but it is preferable to use TMAH having a concentration higher than this concentration, for example, in the range of 2.38 wt% to 25 wt%. According to this, even a portion of the photoresist film 15a that has not been sufficiently exposed can be melted, and thus the scum can be removed. As in the case of the first modification, the first having a substantially rectangular cross-sectional shape. Pattern 15a is formed.

(Modification 3)
In the third modification, an acidic solution is applied to the exposed photoresist film 15 and the photoresist film 15 is heated. As the acidic solution, for example, a top antireflection coating (TARC) solution or a photoacid generator (PAG) solution can be used. Further, it is preferable to provide the coating and developing apparatus 30 with a unit having the same configuration as the coating unit and the developing unit for supplying the acidic solution.

  When an acidic solution is applied to the exposed photoresist film 15, the crosslinking reaction of the photoresist proceeds with the acid, so that it is insolubilized in the developer. For this reason, even a portion of the photoresist film 15 that is not sufficiently exposed is not dissolved in the developer, and the occurrence of scum is suppressed.

  The present invention has been described above with reference to some embodiments and modifications. However, the present invention is not limited to the above-described embodiments, and various changes or modifications can be made in light of the appended claims. Is possible.

  For example, in the above-described embodiment, after the photoresist film 15 is formed, PAB is performed while exposing the photoresist film 15 to the HMDS gas in the deactivation processing apparatus 10, but in other embodiments, PAB may be performed by a heating unit in the processing unit group 63 after the photoresist film 15 is exposed to the HMDS gas without heating the wafer W by the deactivation device 10 (at room temperature).

  In the above-described embodiment, the photoresist film 15 is exposed to the HMDS gas in the deactivation processing apparatus 10, but after forming the photoresist film 15 with the COT layer L3, for example, the wafer W is placed on the TCT layer L4. The HMDS solution may be supplied to the photoresist film 15 in the processing unit in the TCT layer L4. This also provides the same effect as when using HMDS gas. Further, after the treatment with the HMDS solution, PAB is performed by the heating unit in the treatment unit group 63.

  The effect of the HMDS gas or the HMDS liquid can be exhibited even after the photoresist film 15 is exposed. That is, after the photoresist film 15 is exposed, the wafer W may be transferred to the deactivation processing apparatus 10 where the photoresist film 15 may be exposed to HMDS gas, or the wafer W may be exposed to a processing unit in the TCT layer L4. The HMDS liquid may be supplied to the photoresist film 15 here. Thereafter, a post-exposure bake (PEB) is performed on the wafer W.

  Further, after the photoresist film 15 is exposed, when the treatment with the HMDS gas or the HMDS liquid and the treatment with the acidic solution of the above-described modification 3 are performed, the treatment with the acidic solution is performed after the treatment with the HMDS gas or the HMDS liquid. Preferably it is done.

  After exposing the photoresist film 15 to the HDMS gas, an immersion protective film for immersion exposure may be formed on the photoresist film 15.

  In the above-described embodiments (and modifications), the photoresist film 15 is exposed to HMDS gas or HMDS solution to neutralize the acid generated during the exposure. However, the present invention is not limited to HMDS. For example, a gas containing an amine compound or a pyrrolidone compound can be used. Examples of amine compounds include silane coupling agents, NMP, hexamine, dicyclohexylamine, and triethylamine. Examples of silane coupling agents include TMSDMA and DMSDMA in addition to HDMS. An example of the pyrrolidone compound is N-methylpyrrolidone (NMP). In addition, ammonia, glycine, aniline, pyridine, hydroxylamine, choline, sodium hydroxide, potassium hydroxide, quencher, and the like may be used instead of HDMS.

  DESCRIPTION OF SYMBOLS 10 ... Deactivation processing apparatus, 11 ... Etching object film, 12 ... 1st inorganic material film, 13 ... 2nd inorganic material film, 14 ... Inorganic antireflection film, 15 * .. Photoresist film, 30... Coating and developing device, B1... Carrier block, B2... Processing block, B3... Interface block, B4.

Claims (16)

Forming a photoresist film on the substrate;
Exposing the photoresist film to an alkaline agent;
Exposing the photoresist film exposed to the agent;
Developing the exposed photoresist film. A photoresist pattern forming method.   The photoresist pattern forming method according to claim 1, wherein in the exposing step, the photoresist film is exposed to a gas or vapor of the chemical.   3. The photoresist pattern formation according to claim 1, further comprising a first heating step for heating the photoresist film, the first heating step being performed together with or after the exposing step. 4. Method. Prior to the developing step,
4. The method of forming a photoresist pattern according to claim 1, further comprising a second heating step of heating the substrate on which the exposed photoresist film is formed. 5. Prior to the developing step,
4. The method according to claim 1, further comprising a third heating step of bringing an acidic solution into contact with the exposed photoresist film and heating the photoresist film in contact with the acidic solution. 5. Photoresist pattern forming method.   6. The exposed photoresist film is developed using an aqueous tetramethylammonium hydroxide solution having a concentration higher than 2.38 wt% in the developing step. 6. Photoresist pattern forming method.   The method for forming a photoresist pattern according to claim 1, wherein the photoresist film is formed from a chemically doubled photoresist solution.   The method for forming a photoresist pattern according to any one of claims 1 to 7, wherein the agent contains an amine compound or a pyrrolidone compound. Forming a first film and a second film made of different materials in this order on an etching target film formed on a substrate;
Forming a photoresist film on the second film;
Exposing the photoresist film to an alkaline agent;
Exposing the photoresist film exposed to the agent;
Developing the exposed photoresist film to form a first pattern having a predetermined pattern;
Forming a first core part on which a silicon-containing film can be deposited by reducing the first pattern;
A silicon-containing film covering the first core part is formed, and the silicon-containing film is etched back to form a second pattern including the silicon-containing film deposited on the side surface of the first core part. And a process of
Etching the second film using the second pattern to form a second core portion on which a silicon-containing film can be deposited;
A silicon-containing film covering the second core portion is formed, and the silicon-containing film is etched back to form a third pattern including the silicon-containing film deposited on the side surface of the second core portion. And a process of
Forming an etching mask for etching the film to be etched by etching the first film using the third pattern.   The method of forming an etching mask according to claim 9, wherein, in the exposing step, the photoresist film is exposed to a gas or vapor of the chemical.   11. The etching mask forming method according to claim 9, further comprising a first heating step for heating the photoresist film, the first heating step being performed together with the exposure step or after the exposure step. . Prior to the developing step,
The etching mask formation method according to any one of claims 9 to 11, further comprising a second heating step of heating the substrate on which the exposed photoresist film is formed. Prior to the developing step,
12. The method according to claim 9, further comprising a third heating step of bringing an acidic solution into contact with the exposed photoresist film and heating the photoresist film in contact with the acidic solution. Etching mask formation method.   14. The exposed photoresist film is developed using an aqueous tetramethylammonium hydroxide solution having a concentration higher than 2.38 wt% in the developing step. 14. Photoresist pattern forming method.   The method for forming a photoresist pattern according to claim 9, wherein the photoresist film is formed from a chemically doubled photoresist solution.   The method for forming a photoresist pattern according to claim 9, wherein the agent contains an amine compound or a pyrrolidone compound.

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