JPH03138922A - Minute-pattern forming method - Google Patents

Abstract

PURPOSE:To form a minute resist pattern having high resolution by projecting ions on an organic film, forming a high density film, applying electron beam resist on the organic film, performing heat treatment, drawing a pattern, developing the pattern, and etching an organic polymer film with the resist pattern as a mask. CONSTITUTION:An organic polymer film as a lower film 12 is applied on a semiconductor substrate 11. Baking is performed. W<+> ions as metallic ions 13 are projected on the film, and a metallic-ion projected region 14 is formed on the lower film. Then, novolac based resist is applied on the region 14 as an upper electron beam resist layer 15. After baking, electron beam lithography is performed. Development is performed with organic alkali solution. Then, with a resist pattern 15P as a mask, the metallic-ion projected region 14 is etched. The lower film 12 is further etched. Thus, the accurate, minute resist pattern without pattern distortion can be formed.

Description

Detailed Description of the Invention: Industrial Field of Application The present invention (1) relates to a method for forming fine patterns used in patterning and manufacturing semiconductor elements and integrated circuits using electron beams, and is not limited to conventional techniques. In the manufacture of ICs, LSIs, etc. (1) Even though pattern formation is performed by photolithography using ultraviolet rays, as elements become smaller, the use of high NAt and short wavelength light sources for stepper lenses is recommended. The disadvantage is that the depth of focus is shallow.
Ma? , fine pattern dimensions of LSI devices (LASIC
As electron beam lithography has come into use, it is one of the most promising methods for forming the micron and submicron geometries required for LSI devices. However, one of the major problems with electron beam lithography is the backscattering effect of electrons in radiation-sensitive organic resist thin films, which can pose practical limitations on resolution and linewidth control. Limitations are also caused by proximity effects and variations in resist thickness reflecting substrate irregularities.
There are other disadvantages such as the poor dry etching resistance of electron beam resists, the impact on pattern accuracy due to the proximity effect due to forward scattering and back scattering of electrons mentioned above, and the influence on pattern writing due to the charge-up of incident electrons.
To overcome these drawbacks, a multilayer resist method in which the functions of the resist are divided into a photosensitive layer and a flattening layer is a very effective method. Figure 6 is a diagram explaining the multilayer resist process in electron beam lithography.In order to suppress the proximity effect, an organic film with a thickness of 2 to 3 μm is used as the lower layer film 61.
An inorganic film such as Sio* or an inorganic polymer film such as SOG (spin-on glass) is applied to a thickness of 0.2 μm as an intermediate layer 62, and an electron beam resist 63 is applied as an upper layer to a thickness of 0.2 μm.
After applying the film to a thickness of 5 μm, approximately 100 people deposited a thin aluminum film on top of it to prevent charge-up (Figure 6(a)). Pattern drawing table The aluminum layer is removed with an alkaline aqueous solution and then developed to obtain a resist pattern (Fig. 6(b)). At dusk, dry etching the intermediate layer using this resist pattern as a mask (Figure 6 (C))
), then dry etching the lower layer using the middle layer as a mask (Figure 6(d)). By using the multilayer resist process described above, it is possible to form fine patterns with a high aspect ratio. Problems to be Solved by the Invention As mentioned above, the multilayer resist process is an effective method. However, in the case of electron beam exposure, the proximity effect caused by the scattering of incident electrons has a large effect on pattern accuracy, so it is necessary to apply a thick underlayer film.
1. It is impossible to completely suppress the proximity effect with a thickness of 3 μm. Furthermore, if a lower layer film with a thickness greater than 1 is applied, the dimensional shift during pattern transfer will become extremely large, and the process will be difficult. In addition, novolac resists and PMMA (polymethyl methacrylate) resists, which are used as electron beam resists, also have the problem of large variations in resist pattern dimensions with respect to development time and small process latitude. Al on the Iζ resist to prevent
The process of forming a thin film! Tomo: When the resist is a novolak resist, it cannot be used, and there is also the problem that the process is complicated. Means for Solving the Problems The fine pattern forming method of the present invention uses the following means.
In other words, Semiconductor substrate 1: A step of applying a polymeric organic film and heat treatment, a step of forming a high-density layer film by ion irradiation on the organic film, and applying an electron beam resist on the organic film. It is also preferable that the ion irradiation onto the polymeric organic film is silicon, silicon, etc. Accelerating metal ions such as tungsten at a voltage of 40kV or more Irradiation amount I x 10”1ons/Cf
Irradiate over f111. In addition, according to the fourth aspect of the present invention, a step of applying a polymeric organic film on a semiconductor substrate and heat-treating the semiconductor substrate, and a step of applying hydrogen ions on the organic film at I.times.
a step of forming a high-density layer film by irradiating the organosilicon compound over a cm"; a step of applying an organic silicon compound on the organic film and heat-treating the organic film; and a step of applying an electron beam resist on the organic silicon compound and heat-treating the organic film. In addition, the present invention provides a method comprising a step of etching an organic silicon compound or a polymeric organic film using a developing resist pattern as a mask for pattern drawing. The process of
A step of applying an alloy metal inorganic polymer film on the organic film and heat-treating it, a step of applying an electron beam resist on the inorganic polymer film and heat-treating it, and a step of pattern drawing. The present invention provides a method comprising a step of etching a molecular film or a polymeric organic film.The present invention uses the above-described resist process to easily produce accurate fine patterns with less pattern deterioration due to the proximity effect (＼ without pattern deviation due to charge-up). In particular, by using an alloy metal inorganic polymer that can be coated as an intermediate layer, a high-density layer can be easily formed, suppressing the proximity effect and charge-up, and achieving a high process margin. Therefore, by using the present invention, it is effective to form an accurate, high-resolution fine resist pattern. is a metal ion, S
By irradiating the underlying film with i-ions or hydrogen ions, a high-density layer is formed on the underlying film to solve the above-mentioned problems such as pattern inferiority due to the proximity effect and charge-up effect in electron beam lithography. Amo Incoming electrons in electron beam lithography are scattered in the resist and reach the substrate, and back scattering from the substrate reaches the resist again. Therefore, in an integrated pattern: Top By scattering electrons from nearby patterns, the desired A pattern cannot be obtained\ The problem of proximity effect occurs.A To prevent this proximity effect, a high-density layer is formed on the lower layer.The density of this high-density layer is approximately 5 to 20 g/c.
This layer makes it possible to control the amount and direction of electron backscattering, and to suppress pattern deterioration due to the proximity effect.Metal ions include Tungsten, Renium, Platinum, and Even if metals such as gold are used, it is also possible to form a high-density layer using Si ions or hydrogen ions.In addition, incident electrons in electron beam lithography are accumulated in the underlying film, which is an insulating film, and the electron beam Bending The pattern is distorted and the problem of charge-up effect occurs. Ion-irradiated M (Friend) Since the surface resistance is lower, this charge-up can be prevented. Although a resist process with a high process margin can be obtained with little change in Polymers (soluble in friendly solvents and can be coated) can easily form a high-density layer. Therefore, backscattered electrons due to adjacent patterns can be controlled and the proximity effect can be suppressed. Since it is a metal, it has a low resistance value and can prevent charge-up, making it possible to obtain a resist process with a high process margin. By applying a thin aluminum film, charge-up due to incident electrons can be prevented, and
Minimal change in resist pattern dimensions with respect to development time
It is possible to obtain a resist process with a high process margin and form an accurate fine resist pattern without batting errors or misalignment (Example 1) A first example of the present invention is shown in FIG. . semiconductor substrate 11
A 2 μm thick polymeric organic film is coated on top as the lower layer 12 LA
220'D Baked for 20 minutes and accelerated the W0 ion as metal ion 13 to No. 1 at a voltage of 40
kV, irradiance 1 x 10”1ons/Cm2
The entire surface is irradiated to form a metal ion irradiation region 14 with a thickness of 0.1 μm on the lower layer film 7-o (FIG. 1(a)). Place it on top of this as electron beam resist 15 A Z 13
Apply 50J novolak resist to a thickness of 0.5 μm,
Baking was performed at 100 tons for 90 seconds (Fig. 1(b)). Next, acceleration voltage 20kV, dose amount 30
Row 1 of electron beam exposure at μc/cm2. % organic alkali aqueous solution, there was little proximity effect ＼ No pattern shift due to charge-up ＼ ＼ It was possible to form an accurate fine resist pattern (Figure 1 (C)
). Using this resist pattern as a mask, the metal ion irradiation region 14 was etched, and the underlying film 12 was further etched to obtain an accurate and vertical fine resist pattern (FIG. 1(d)). Acceleration voltage 40kV
By forming a 0.1μ thick W0 ion irradiation layer with an irradiation dose of 1×10” 1ons/c, a high-density layer can be formed on the underlying film, and the backscattering of incident electrons in electron beam writing can be reduced. The proximity effect caused by adjacent patterns can be suppressed, and a resist pattern with less proximity effect can be formed.

In addition, since it is a metal ion layer, charges caused by incident electrons are not accumulated, and a charge-up effect does not occur. 1 friend Accelerating voltage 40kV or less, irradiation amount 1 x 10" 1o
The metal ion may be a metal other than W or may be Sio.

(Example 2) A second example of the present invention is shown in FIG. semiconductor substrate 11
A 2 μm thick polymeric organic film is applied on top as the lower layer 21 L2
20＼ Baking for 20 minutes, hydrogen ions 22 accelerated voltage 40kV, irradiation amount I x 1
0"1ons/am" whole surface-batch irradiation, lower layer film 1 screen 0"
．． A 3 μm thick high-density layer was formed by hydrogen ion irradiation (FIG. 2(a)). In this one, SOG was applied to a thickness of 0.1 μm as the intermediate layer 23, and AZ 2400 novolak resist was applied to a thickness of 0.5 μm as the heat-treated upper layer resist 24, 100t, 90sec.
Baking was performed (Fig. 2(b)). Next, electron beam exposure was performed at an accelerating voltage of 20 kV and a dose of 30 μc/c. ) After developing with an organic alkaline aqueous solution,
It was possible to form an accurate fine resist pattern (FIG. 2 (C)) with little proximity effect I, Then, Iζ
By dry etching the lower film 21, an accurate and vertical fine resist pattern could be obtained (second
Figure (d)). By forming a 0.3 μm thick H0 ion irradiation layer with an acceleration voltage of 40'/cm2 and a irradiation dose of 1 x 101 tes/cm2, a high-density layer can be formed on the underlying film, and the incident electrons in electron beam lithography can be The backscattering of the hydrogen ion irradiated layer (friend
The resistance of the surface of the lower layer film is lowered, and it is possible to prevent charge-up during drawing.
The film thickness can be changed arbitrarily depending on the accelerating voltage during irradiation and the irradiation dose.It is effective to use an accelerating voltage of 40 kV or less and a irradiation dose of LX of 10"1 ons/cm2 or more. This is shown in Figure 5. In the case of a normal three-layer resist process in which the underlying film is not ion irradiated, as the development time becomes longer, the resist pattern dimensions gradually become thinner. In the case of the new three-layer resist process that forms a high-density layer, the development time is longer and the k
Although the resist pattern dimensions hardly change, the process latitude can be made very large (Embodiment 3) A third embodiment of the present invention is shown in FIG. semiconductor substrate ll
On top, a 2 μm thick polymeric organic film is applied as the lower layer 31 L2
Baking was performed at 20°C for 20 minutes. Hydrogen ions were then accelerated at a voltage of 40 kV and a dose of 1x I O".
1ons/Cm” full-surface irradiation to deposit O4 on the lower layer film.
“A hydrogen ion irradiation region 33 with a thickness of 3 μm was formed (third
Figure (a)). Furthermore, on top of this, a 0.5 μm thick resist containing silicon was applied as the upper layer resist 34.
'tE, baked for 10 minutes (3rd E
m(b)).

(1) Acceleration voltage 20kV, dose 20μe/c
When electron beam exposure was performed and development was performed with xIPA (6 isobrobylyalcohol), there was little proximity effect, accurate fine patterning with no pattern shift due to charge-up,
';-(The pattern could be formed ((3rd
Figure (C)). Using this resist pattern as a mask, the lower layer film 31 is etched in rows 1. L It was possible to obtain an accurate and vertical fine resist pattern (Fig. 3(d)).

In addition, the variation in resist dimensions with respect to development time is small.
Process margin can be increased (Embodiment 4) A fourth embodiment of the present invention is shown in FIG. semiconductor substrate 11
On top, a 2 μm thick polymeric organic film is applied as a lower layer 41 L2
Baking was performed at 20°C for 20 minutes (Figure 4(a)
). On this, a polytungstic acid polymer, which is a metal-containing inorganic polymer, is applied to a thickness of 0.2 μm as an intermediate layer 42, and after heat treatment, a PMMA (polymethyl methacrylate) resist is applied to a thickness of 0.5 μm as an upper layer resist 43.
Baking was performed at 170°C for 20 minutes (see Figure 4).
b)). Next Acceleration voltage 20kV.

Electron beam exposure was performed at a dose of 200 μc/cm” (＼ T
When PA development was performed, it was possible to form an accurate fine resist pattern with little proximity effect (no pattern shift due to charge-up) (Figure 4 (C)). Using this resist pattern as a mask, the intermediate By dry etching the lower layer 41 after etching the layer 42, an accurate and vertical fine resist pattern could be obtained (FIG. 4(d)).As described above, according to this example, (Dai) By applying a metal-containing inorganic polymer to the middle layer of a three-layer resist to form a high-density film, it is possible to form a fine resist pattern with high precision. By irradiating metal ions, silicon, or hydrogen ions on the lower layer film, by forming a thin high-density layer, it is possible to control the scattering of incident electrons during electron beam writing, and the proximity effect due to adjacent patterns・By charging up the incident electrons, it is possible to form accurate and fine resist patterns with no pattern distortion. In addition, by coating a metal-containing inorganic polymer on the lower layer film to form a high-density layer, it is possible to reduce the proximity effect (＼ ＼ charge-up occurs). It is possible to form a resist pattern with a high density, making it possible to greatly contribute to the production of ultra-high density integrated circuits.

[Brief explanation of the drawing]

Figure 1 (top) A cross-sectional view of the process of the first embodiment of the present invention Figure 2 is a cross-sectional view of the process of the second embodiment Figure 3 is a cross-sectional view of the third embodiment of the invention Figure 4 is the same A cross-sectional view of the process of the fourth embodiment. Figure 5 is a graph showing the development time and the change in line width of the upper resist pattern in Example 2. Figure 6 is a cross-sectional view of the process of the conventional multilayer resist method. Amo

Claims (4)

[Claims] (1) A step of applying and heat-treating a polymeric organic film on a semiconductor substrate, a step of forming a high-density layer film on the organic film by irradiating ions, and applying an electron beam resist on the organic film. 1. A method for forming a fine pattern, comprising the steps of coating and heat-treating the film, and after drawing the pattern, developing it and etching the polymeric organic film using the resist pattern as a mask. (2) A patent claim characterized in that the polymeric organic film is irradiated with metal ions such as silicon or tungsten at an acceleration voltage of 40 kV or less and a irradiation dose of 1×10^1^6 ions/cm^2 or more. The fine pattern forming method according to item 1. (3) A process of applying and heat-treating a polymeric organic film on a semiconductor substrate, and adding 1×10^1 hydrogen ions onto the organic film.
A step of forming a high-density layer film by irradiating at ^6 ions/cm^2 or more, a step of applying an organic silicon compound on the organic film and heat-treating it, and applying an electron beam resist on the organic silicon compound. 1. A method for forming a fine pattern, the method comprising: a heat treatment step; and a step of developing the pattern after drawing it and etching the organic silicon compound or polymeric organic film using the resist pattern as a mask. (4) A step of applying an organic polymer film on the semiconductor substrate and heat-treating it; a step of applying a metal-containing inorganic polymer film on the organic film and heat-treating it; and a step of applying an electron beam resist on the inorganic polymer film. After the pattern is drawn and developed, the inorganic polymer film is formed using the resist pattern as a mask.
A method for forming a fine pattern, comprising the step of etching a polymeric organic film.