JPS6346094B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A novel organopolysiloxane, ie, silicone resin, having a ladder-type structure and the use of the silicone resin as a resist material are disclosed. The resist material of the present invention has high sensitivity to ionizing radiation, especially to X-rays.

[Industrial application field]

The present invention relates to phosphorography technology, particularly phosphorography using ionizing radiation such as electron beams, Regarding graphie technology. More specifically, the present invention relates to an organopolysiloxane (hereinafter also referred to as a silicone resin) having a ladder-type structure, which is novel in this technical field, and its use as an ionizing radiation resist material.

[Conventional technology]

As semiconductor devices become more highly integrated, resist materials used in phosphorography technology are also being improved day by day. For example, chloromethylated polystyrene (CMS), cyclized polyisoprene, and the like are widely used as negative resist materials for electron beams and X-rays. However, these materials have not yet fully satisfied both sensitivity and resolution.

Recently, a method has been realized in which a resist film has a two-layer structure to obtain a more satisfactory resist pattern. However, the resist materials developed for this patterning method, such as SNR, CMS, and trimethylsilylstyrene copolymers, still lack sufficient sensitivity. Particularly when used in X-ray phosphorography, the sensitivity of the resist material must be approximately twice that of conventional resist materials.

[Problem that the invention seeks to solve]

An object of the present invention is to eliminate the drawbacks of the conventional techniques as described above, in other words to provide a resist material that has high sensitivity to ionizing radiation, especially X-rays.

[Means for solving problems]

In the course of research to achieve the above-mentioned objective, the present inventors discovered that polymethylsilsesquioxane and polyvinylsilsesquioxane, which have a ladder structure, are particularly sensitive to electron beams. As a result of further research, we discovered a novel organopolysiloxane represented by the following structural formula ().

In the above formula, R ₁ is −C _n H _2n+1 , for example −CH ₃ , −C ₂ H ₅ , −
C ₃ H ₇ , −C _n H _2n-1 , e.g. −CH=CH ₂ , −CH ₂ −
CH= _CH2 ; or _{-C6H5 ,} and _R2 is _-CnHkClL ( _k + _l =2m+1,m2),
For example, −C ₂ H ₄ Cl, −C ₃ H ₆ Cl, CHCl−CH ₂ Cl, −
_CH2- CHCl- _CH2Cl , m represents an integer of 1 to 5, and n represents the degree of polymerization necessary to provide a molecular weight (Mw) of 5000 to 200000.

n in the above formula is preferably about 40 to 1500. Furthermore, the organopolysiloxane of the above formula is silylated at its terminal. Here, silylation means that all three hydrogens bonded to a Si atom are not replaced, or some or all of such hydrogens are replaced with an alkyl group such as a methyl group. This means that a silyl group has been introduced.

Further, as a result of research, it has been found that the organopolysiloxane of the above formula () is useful as a resist material for ionizing radiation, particularly as a resist material for sensitive X-rays (PdLα rays, MoLα rays, etc.). It has been found that the resist material of the present invention can be advantageously used as the top layer of a two-layer resist film. This two-layer resist film can be subjected to pattern formation, for example, in the following manner: irradiating an image pattern of ionizing radiation to form a latent image corresponding to the image pattern on the upper resist thin film; Develop the latent image with a developer to obtain an upper resist pattern, perform rinsing if necessary, perform plasma treatment using the upper resist pattern as a mask, and transfer the upper resist pattern to the lower resist thin film below. .

The above-described series of steps can be performed using techniques commonly used in this technical field, and therefore detailed description thereof will be omitted here.

According to the invention, vinyl silsesquioxane,
Arylsilsesquioxane or methyl-
After synthesizing vinyl and methyl-aryl coexisting silsesquioxane, unsaturated bonds are halogenated using a halogenating agent such as chlorine gas to introduce halogen atoms into the ladder silicone resin. ) silicone resin can be produced. This manufacturing method is noteworthy in that it does not include the drawbacks of traditional manufacturing methods, such as:
Conventional manufacturing methods include a method of chloromethylating polyphenylsilsesquioxane and a method of condensing and polymerizing halogenated alkyltrichloro(alkoxy)silane to form a polymer. However, in the case of the former method of chloromethylating polyphenylsilsesquioxane, even if chloromethylation is possible, chlorine (Cl) is Since the number of atoms does not increase, the X-ray absorption coefficient does not increase significantly.
On the other hand, in the case of the latter method, the chloromethyl group, chloroethyl group, etc. added to the silicon (Si) atom are highly reactive and tend to gel. If monomers with long alkyl chains are used to prevent gelation, it becomes impossible to increase the molecular weight.

〔Example〕

Example 1 (Preparation example) In 100ml of methyl isobutyl ketone (MIBK)
18 ml of triethylamine was added and mixed, and the mixture was further mixed with 30 g of vinyltrichlorosilane and cooled to -50°C. After adding 18 ml of water to the resulting mixture, the temperature of the solution was gradually returned to room temperature. Next, while bubbling with nitrogen gas, the temperature of the reaction solution was raised to 100°C.
Polycondensation was continued for 10 hours. The formed MIBK layer was collected and 30 g of trimethylchlorosilane was added thereto. The reaction was carried out at 60° C. for 1 hour to silylate unreacted hydroxyl groups. After washing this reaction solution with 500 ml of water 4 or 5 times, acetonitrile was added and the resulting resin precipitate was collected. The recovered resin was again dissolved in 50 ml of MIBK, and chlorine gas was bubbled into it all day and night to chlorinate the vinyl groups. After this chlorination, a resin precipitate was formed by adding acetonitrile, collected, dissolved in benzene, and lyophilized.
When the obtained resin was analyzed by gas phase chromatography, it was confirmed that it had the following structure:=1.0×10 ⁵ , w/n=1.8.

Example 2 Preparation The procedure described in Example 1 above was repeated. However, in the case of this example, a mixture of 10 g of methyltrichlorosilane and 20 g of vinyltrichlorosilane was used instead of 30 g of vinyltrichlorosilane, and in order to chlorinate the recovered resin, 6 g of it was mixed with 50 ml of benzene. 1 g of benzoyl peroxide and 5
g of N-chlorosuccinimide was added and allowed to react at reflux temperature for 10 hours. When the obtained resin was analyzed by gas phase chromatography, it was confirmed that it had the following structure: w=
7×10 ⁴ , w/w=1.6.

Example 3 A solution obtained by dissolving the resin of Example 1 in diisobutyl ketone (DiBK) was spin-coated onto a silicon substrate, and prebaked at 100° C. for 30 minutes. Next, the formed resist film is coated with
PdLα radiation (wavelength λ = 4.37 Å) was irradiated imagewise.
At this time, the tube voltage was 15 kV and the tube current was 100 mA. After image exposure, the sample was immersed in MIBK for 60 seconds for development, and then was developed using isopropanol (IPA).
immersed in water for 30 seconds and rinsed. The sensitivity of the resist in this example was 70 mJ/cm ² .

Example 4 The procedure of Example 3 above was repeated using the resin of Example 2 above. The sensitivity of the resist in this example was 120 mJ/cm ² .

Example 5 This example was carried out in the sequence shown in cross-section in the accompanying Figures 1a-1d.

A resist: Microposit 1350 manufactured by Shippray Co., Ltd., USA, is spin-coated on the silicon substrate 1.
Heat treatment was performed at 200°C for 1 hour. Film thickness
A 2.0 μm lower resist film 2 was obtained. Next, on the formed lower resist film 2, the above-mentioned Example 1 is applied.
The resist was spin-coated and prebaked at 100°C for 30 minutes. The thickness of the upper resist film 3 was 0.2 μm. FIG. 1a is a schematic cross-sectional view of a silicon substrate with a two-layer resist film thus obtained.

Next, the obtained silicon substrate with the two-layer resist film was placed in a PdLα ray exposure device, and contact exposure was performed through a mask (not shown) having a 0.8 μm thick Ta pattern on a 3 μm thick polyimide membrane. (Figure 1b). 3a in the figure is an exposed area, and 3b is an unexposed area.

Next, the exposed silicon substrate was placed in a DiBK bath for 60 minutes.
It was developed by immersing it in IPA for 30 seconds, and then rinsing by immersing it in IPA for 30 seconds. 1st c
As shown in the figure, the upper resist film 3 in the exposed area
Only portion a remained on the lower resist film 2 as the upper resist pattern.

Next, the developed silicon substrate is placed in a parallel plate dry etching device, and exposed to oxygen plasma (gas pressure 2 Pa, applied voltage 0.22 W/cm ² ) using the remaining upper resist film 3a as a mask and a carbon target. Plasma etching was performed for 15 minutes. As a result of this etching, the upper resist pattern 3a was directly transferred to the lower resist film (flattening layer) 2a, as shown in FIG. 1d.

In this example, a 0.5 μm line and space pattern was resolved.

〔Effect of the invention〕

According to the present invention, a resist is provided that has high sensitivity to ionizing radiation, in particular to X-rays. This resist has not only high sensitivity but also high resolution.

[Brief explanation of drawings]

FIGS. 1a, 1b, 1c, and 1d are schematic cross-sectional views sequentially showing an example of a pattern forming method using the resist material of the present invention. In the figure, 1 is a silicon substrate, 2 is a lower resist film, and 3 is an upper resist film.

Claims (1)

[Claims] An organopolysiloxane represented by the following structural formula () and whose terminals are silylated. (In the above formula, R ₁ is −C _n H _2n+1 , −C _n H _2n-1 , or −C ₆ H ₅ , and R ₂ is −C _n H _K Cl _L (k+L=2 _n +1, m2 ), m represents an integer from 1 to 5, and n represents the degree of polymerization necessary to give a weight average molecular weight of 5,000 to 200,000. Organopolysiloxane in which is silylated: (In the above formula, R ₁ is −C _n H _2n+1 , −C _n H _2n-1 , or −C ₆ H ₅ , and R ₂ is −C _n H _K Cl _L (k+L=2 _n +1, m2 ), m represents an integer of 1 to 5, and n represents the degree of polymerization necessary to provide a weight average molecular weight of 5000 to 200000). 3. The resist material according to claim 2, which is used as an upper layer of a two-layer resist film. 4. The resist material according to claim 2 or 3, which is ionizing radiation. 5. The resist material according to claim 4, wherein the ionizing radiation is an X-ray.