JPH0772798B2 - Pattern formation method on substrate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a substrate having a pattern formed thereon, and more particularly to a method for manufacturing a substrate capable of providing a high resolution pattern having a line width of 1 μm or less. .

(Prior Art) As a method for developing a resist material, far-ultraviolet light exposure, electron beam exposure, or X-ray exposure has hitherto been performed.
In this case, there is a drawback that not only a long exposure time is required but also a dark room is required, and as the exposure time becomes long, an image shifts and a high resolution cannot be obtained.
In this regard, it has been proposed to form a fine pattern by excimer laser irradiation in order to perform short-time exposure.

Also, these far ultraviolet light exposure or electron beam exposure,
As a positive resist material used for X-ray exposure, polymethacrylic acid ester such as polyethylmethacrylate has been widely used because of its excellent light transmittance.

However, these conventional compounds have low light absorption including far-ultraviolet light, and therefore, it is difficult to reduce the molecular weight of the resist film to a deep portion by exposing to far-ultraviolet light, and thus the film sagging in the exposed portion is difficult. However, the number of irradiations needs to be performed several thousand to 10,000 times to form a sufficient pattern, and the large number of irradiations causes focal vibration and blurring of the pattern. Improved absorption was desired. At the same time, in order to form a high-resolution pattern on the substrate, not only improvement of the material of the film but also examination of film thickness and irradiation energy density has been desired.

(Problems to be Solved by the Invention) Accordingly, it is an object of the present invention to provide a method for producing a substrate capable of forming a high resolution pattern.

(Means for Solving Problems) The above-mentioned object is a copolymer of a vinyl monomer having a coloring group having an absorption peak in the ultraviolet wavelength region and a polymethacrylic acid ester and having a viscosity average molecular weight of 1 × 10 ⁶ to. A positive resist film of 1 × 10 ⁷ is formed on the substrate to a film thickness of 100Å to 1 μm, and short wavelength light of 300 nm or less is emitted at 200 mJ / cm ² through a reticle.
Irradiate 1 to several times with an energy density of ~ ² J / cm2, the number average molecular weight of the irradiated part of the resist film is reduced to 10 ³ order, and the irradiated part of the resist film is subjected to baking treatment. Is removed to form a fine pattern on the substrate, which is achieved by a pattern forming method on the substrate.

Therefore, the developing method of the resist material of the present invention is such that the high molecular polymer existing in the exposed portion of the resist material formed on the substrate is decomposed or reduced to generate a reaction, and then the reaction is generated by the development treatment. Objects can be selectively removed, and high-resolution patterns are expected to be obtained.

Here, the developing treatment means a treatment for selectively removing a reaction product.

The resist material of the present invention is required to have good irradiation energy absorption as well as transmittance for a beam having a short wavelength of 300 nm or less. Such a resist material has a viscosity average molecular weight of 4.33 × 10 ⁵ or more (intrinsic viscosity η of 1 × 10 ² or more), more preferably 1.08 × 10 ^{6 to} 5.56 × 10 ⁷ (intrinsic viscosity of 2 × 10 ² to A polymethacrylic acid ester-based copolymer having a size of 4 × 10 ³ ) is preferable. The value of intrinsic viscosity here is the value at 30 ° C. Examples of the polymethacrylic acid ester include methacrylic acid having an ester group composed of an alkyl group having 1 to 4 carbon atoms, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. Esters are preferable, and methyl methacrylate is particularly preferable.

Among the above-mentioned resist materials, preferred high molecular weight polymethacrylic acid ester-based polymers include copolymers with other vinyl monomers having a coloring group having an absorption peak in the ultraviolet wavelength range. In such a copolymer, the other monomer incorporated in the copolymer has a photosensitizing action, so that the sensitized light absorption property depends on external factors such as temperature. It is extremely stable and exhibits high etching efficiency. As the methacrylic acid ester that constitutes this copolymer,
A methacrylic acid ester having an ester group composed of an alkyl group having 1 to 4 carbon atoms such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate and the like is preferable, and methacrylic acid is particularly preferable. Methyl is preferred.

On the other hand, other vinyl monomers having a color-forming group having an absorption peak in the ultraviolet wavelength region include vinyl monomers having an aromatic ring or a heteroaromatic ring as a color-forming group, preferably vinyl biphenyl, vinyl pyridine, N- Examples include vinylcarbazole and vinylnaphthalene.

The method for producing a high-molecular-weight polymethacrylic acid ester-based copolymer relating to the formation of a pattern of the present invention is performed by irradiating a plasma in a gas phase containing a monomer vapor, and generating a polymerization initiation active species, for example, benzoyl peroxide, dioctane. It can be easily and efficiently adjusted by a plasma-initiated polymerization method in which a radical polymerization initiator for carrying out chain growth polymerization of monomers such as syl peroxide, azopisisobutyrontolyl and the like is used together.

The short-wavelength light used is preferably one having a wavelength of 300 nm or less in order to form a high-resolution pattern after development.
There are X-ray beam, electron beam, excimer laser beam, etc., but as the excimer laser beam, KrF (2
49nm), ArF (193nm), F ₂ (157nm), KrCl (222nm),
ArCl (175 nm), XeBr (282 nm) and the like are preferable, and KrF is particularly preferably used.

In order to form a pattern on the substrate, an excimer laser beam is applied to the resist film formed on the substrate via a reticle. Here, the reticle is a masking material used for forming a pattern on the resist film.

The energy of the short wavelength light to be irradiated is ² J / cm ² or less, and particularly preferably 200 to 1000 mJ / cm ² . If it is less than 200 mJ / cm ² , high resolution of the pattern cannot be obtained, and if it exceeds ² J / cm ² , ablation occurs.

Suitable substrates for use include silicon, glasses, metal oxides, ceramics, alumina, IrOx and PdOx.

The thickness of the resist film is preferably 100Å to 1 μm, and particularly preferably 400 to 2000Å. If it exceeds 1 μm, it becomes difficult for laser light to pass through the resist material, and only the surface of the resist film is drawn, and a high-resolution pattern cannot be obtained. On the other hand, if it is less than 100Å, the effect of film coating is reduced due to the unevenness of the substrate.

(Operation) Thus, preparation of the substrate on which the pattern of the present invention is formed, (1) 2J / cm ² or less, in particular laser light irradiation of 1 J / cm ² or less of KrF (249 nm), the resist film, The number average molecular weight can be lowered to the order of 10 ³ .

(2) 200 mJ / cm ² or more, especially when the irradiation energy of the laser light is 1 J / cm ² or more, the laser light can reach the vicinity of the interface between the resist film and the substrate, and can be useful as a positive resist. .

(3) Since the resist film can be made into a low molecular weight up to the limit where ablation occurs, the low molecular weight portion is easily peeled off by the irradiation of the laser beam during the post-baking or development processing, so that a high resolution pattern is formed on the substrate. It is formed.

(Examples) Hereinafter, the present invention will be specifically described based on Examples.

Example 1 2.67 ml (2.50 × 10 ^-2 mol) of methyl methacrylate (MMA) was added to a Pyrex glass polymerization tube (volume: 42 ml) having an inner diameter of 15 mm.
2-Vinylnaphthalene (2VNP) 6.40 x 10 ² g (4.17 x 10 ^-4
mol) and benzoyl peroxide (BPO) 3 × 10 ^-3 g (4.13
X 10 ^-3 mol) was added, the polymerization tube was connected to a vacuum line, and frozen with liquid nitrogen.

This system was degassed at 10 ^-3 Torr or less, and oxygen in the system was sufficiently fed to melt it again. After repeating this operation three times, the cock was closed and plasma was generated in the gas phase when a part of the monomer in the polymerization tube started to be dissolved. Plasma treatment was performed for 60 seconds at 50 W by a high frequency generator of 13.56 MHz.

The polymerization tube was sealed, left standing at 25 ° C., and polymerized for 5 days. The obtained polymerization reaction product was dissolved in 100 ml of benzene, reprecipitated with ethanol 2.01 and purified to obtain a white polymer. The weight of the produced polymer is 0.18 g (yield 7.5 wt%). The intrinsic viscosity [η] of this polymer at 30 ° C is 5.
It was 99 × 10 ² . In addition, mark hoe wink type [η]
= KM ^α , the viscosity average molecular weight obtained by substituting the coefficients K = 5.2 × 10 ³ and α = 0.76 was 4.57 × 10 ⁶ (number average molecular weight 1.16 × 1
It was 0 ⁶ ).

A 1.2 wt% solution of the obtained polymer in methyl isobutyl ketone (MIBK) was spin-coated (Mikasa Co., Ltd.) at 2000 rpm to form a thin film having a thickness of 1000Å on a silicon wafer, and then prebaked ( 110 ° C, 30 minutes), 1K / cm ² (5 times irradiation, 200mJ / cm ² per irradiation) with KrF excimer laser (249nm) through a 0.5μm line width reticle.
Irradiate, post-baking (170 ℃, 30 minutes),
A fine pattern having a line width of 0.5 μm was obtained.

(Test Example 1) The change in the viscosity average molecular weight of the resist thin film (1000Å) formed on the silicon substrate used in Example 1 was measured under the KrF (249 nm) excimer laser irradiation conditions.

At this time, the experiment of the change of the molecular weight distribution was carried out by using a gel permeation chromatograph (manufactured by JASCO Corporation; TRIROTA VI) as columns such as G 7000HXL and GMH 6 manufactured by Toyo Soda Co., Ltd.
It measured using the column apparatus which attached.

The results are shown in Table 1.

In addition, each molecular weight distribution curve is shown in FIG. Since the resist film is a thin film, the degree of change in molecular weight was determined by the number average molecular weight.

According to these results, the number average molecular weight (Mn) only changes from 1.16 million to 89,900 even after post-baking without laser irradiation after pre-baking (110 ° C, 30 minutes).

After pre-baking, the KrF excimer laser irradiation dose is 60,100,
When changed to 200,1000 mJ / cm ² , the number average molecular weight was
6.62 × ⁵ , 4.49 × 10 ⁵ , 1.56 × 10 ⁵ , 6.57 × 10 ³ , respectively,
The molecule was remarkably low.

(Test Example 2) The total energy of KrF laser irradiation was set to 1 J / cm ² , and the irradiation frequency was 20 times (1 irradiation energy 50 mJ / cm ² ), 10 times (1 irradiation energy 100 mJ / cm ² ), The change in the molecular weight distribution was measured 5 times (one irradiation energy of 200 mJ / cm ² ), and the results shown in Table 2 and FIG. 2 were obtained.

As a result, it was revealed that when the irradiation energy was the same, the decrease in the viscosity molecular weight after irradiation was large if the irradiation energy for one irradiation was large.

When the irradiation energy per irradiation is 200 mJ / cm ² , the number average molecular weight is reduced by as much as 10 ³ order.

Example 2 MMA and 2VNP were charged in a molar ratio of 60: 1, and the same polymerization treatment as in Example 1 was performed to obtain a viscosity average molecular weight of 9.44 × 10 ⁶ polymer (intrinsic viscosity at 30 ° C. [η] = 1.04 × 10 6). ³ ) got

A 1 wt% MIBK solution of the obtained polymer was spin-coated (Mikasa Co., Ltd.) at 2000 rpm to form a thin film with a thickness of 1000 Å on a silicon wafer, and then prebaked (110 ° C, 30 minutes). The KrF excimer laser (249
nm) at 1 J / cm ² (5 times irradiation; once at 200 mJ / cm ² ). The irradiation time for one time was 10 nanoseconds.

Then, baking treatment (170 ° C., 30 minutes) was performed to obtain a fine pattern having a line width of 0.5 μm.

It was revealed that a fine pattern was formed with a low energy irradiation amount without peeling as compared with the image of the resist thin film on the silicon substrate obtained in Example 1.

This is because the limiting molecular weight of the resist film is set to 1 × 10 ² or more (viscosity average molecular weight of 4.33 × 10 ⁵ or more), which enables thinning, excellent adhesion to the substrate, and peeling during baking. This is because it does not occur.

(Test Example 3) The resist thin film on the silicon substrate (40
0 Å) development characteristics, the developer (isopropyl alcohol:
MIBK = 7: 3; volume ratio), and the change in film thickness after drying is measured by a stylus surface profiler (manufactured by Nippon Vacuum Technology Co., Ltd .; DEKTAK).
# 3030).

For comparison, viscosity average molecular weight 1.39 x 10⁶(Comparative Example 1)
And 3.50 × 10^FivePolymethylmethacrylate of Comparative Example 2
Red (Elvsite ; DuPont) MIBK solution
The film thickness adjusted to 400Å by a pinner was used.

This result is shown in FIG. In Comparative Examples 1 and 2, the film swells with the developer and the film thickness changes by 50 to 80 Å, but in this example, the film thickness change is 30 Å. From this, it is clear that in the present embodiment, even the thin film of 400 Å has excellent development resistance.

(Test Example 4) The resist thin film on the silicon substrate (40
FIG. 4 shows the result of Fourier transform infrared spectroscopy (FT-IR) after the irradiation of the excimer laser of 0Å).

For comparison, viscosity average molecular weight 1.39 x 10⁶(Comparative Example 1)
Polymethylmethacrylate (Elvsite ; Dupo
(Manufactured by K.K.) MIBK solution adjusted to a film thickness of 400 Å by a spinner
What was done was used.

909Cm ¹ of _{CH 2 = CHR (R: COOCH} 3) of [delta] (plane deformation) = CHR absorption and 814cm around ¹ based on _{CH 1 = CR 2 R 3 (} R 2: COOC
The absorption based on δ (out-of-plane bending angle) = CH of H ₃ , R ₃ : COOCH ₃ clearly appears, but in Example 1, the absorption at 909 cm ⁻¹ is only slightly observed. This indicates that the photoabsorption reaction to the 2VNP pendant, which is a photosensitizer, is effectively occurring, and hydrogen is abstracted by the naphthalene skeleton. As the analyzer, FTS-10 type manufactured by Nippon Bio-Rad Laboratories Co., Ltd. was used.
Further, the number average molecular weight and the irradiation energy (J / cm ² ) had a linear relationship as shown in FIG.

When the film thickness was 500Å, the number average molecular weight was 7.53 × 10 ³ when irradiated with 1000 mJ / cm ² , and the molecular weight was almost the same as that of 1000Å.

(Effect) The resist thin film formed on the substrate is irradiated with short-wavelength light through the reticle in a short time at ² J / cm ² or less. A substrate on which a fine pattern having a width of 0.5 μm or less is formed can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in molecular weight due to irradiation with KrF laser light, and FIG. 2 is a diagram showing changes in molecular weight due to difference in irradiation energy of KrF laser once. FIG. 3 is a diagram showing the developing characteristics of the resist film, and FIG. 4 is a diagram showing the results of Fourier transform infrared spectroscopy.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-61-209442 (JP, A) JP-A-58-189627 (JP, A) JP-A-61-223837 (JP, A) JP-A-59- 92532 (JP, A) JP-A-57-34550 (JP, A) Semiconductor and integrated circuit technology The 32nd Symposium Proceedings (June 1987) pp. 49-55

Claims (1)

[Claims] 1. A positive type resist having a viscosity average molecular weight of 1 × 10 ⁶ to 1 × 10 ^7, which is a copolymer of a vinyl monomer having a color-forming group having an absorption peak in the ultraviolet wavelength region and a polymethacrylic acid ester. A film is provided on the substrate with a film thickness of 100Å to 1 μm, and short wavelength light of 300 nm or less is emitted through the reticle at 200 mJ / cm ^{2 to 2} J.
Irradiate 1 to 10 times with an energy density of / cm ² to lower the number average molecular weight of the irradiated part of the resist film to the order of 10 ³ and remove the irradiated part of the resist film by baking treatment. The method for forming a pattern on a substrate is characterized by forming a fine pattern on the substrate.