JPS60254132A - Pattern forming material - Google Patents

Abstract

PURPOSE:To form a pattern good in heat stability by silylating intramolecular hydroxyl groups remaining unreacted after condensation reaction of 3-functional siloxane and removing them to form polysilylsesquioxane. CONSTITUTION:A pattern forming material is prepared by silylating polysilsesquioxane having unreacted hydroxide groups remaining in the molecule represented by formula I (in which R1-R4 are each alkyl, such as methyl, chloromethyl, or ethyl, or aryl, such as phenyl or chlorophenyl), with a silylating agent, such as formula II, X being halogen, to bring the hydroxyl groups of the compd. of formula I into reaction with the halogen of the compd. of formula II and to release them in the form of hydrogen halide. This material can form a thermally stable pattern while retaining high sensitivity, high resolution, etc., of the silicone resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to patterning materials. More specifically, the present invention is sensitive to high-energy radiation such as electron beams, The present invention relates to a pattern-forming material which is also thermally stable.

2. Description of the Related Art Conventionally, various devices using semiconductors, ferroelectric materials, ferromagnetic crystals, etc., such as LSIs, bubble memories, surface acoustic wave filters, etc., have extremely fine circuit configurations. For this pattern F/fi1
It is well known that microfabrication technology of micrometers or less is required. Microfabrication technology can be broadly divided into lithography technology and etching technology, and both technologies are showing remarkable progress. For example, in lithography technology, a technology using an electron beam, XTP, or the like having a shorter wavelength as an exposure source has been put into practical use, taking into consideration the reduction in resolution due to light diffraction, interference, and the like. On the other hand, dry etching techniques such as reactive ion etching and sputter etching have recently come into use, making it possible to perform etching with higher precision. Silicone resins with a ladder structure, particularly polysilsesquioxane, are considered as pattern forming materials (resists) that are sensitive to high-energy beams such as electron beams and have excellent dryer resistance, anti-chiking properties, and resolution.

Polysilsesquioxanes can generally be easily synthesized by condensing trifunctional silxanes. For example, polymethylsilsesquioxane is produced by hydrolyzing methyltrichlorosilane as shown in the following reaction formula.
By further condensing this, it can be synthesized: at 0H (I) (n) aH50H30H5 (III) However, in reality, the polymethylsilsesquioxane of the above formula (III) cannot be obtained; As an alternative, polymethylsilsesquioxane in which the hydroxyl group that cannot contribute to the condensation reaction and remains unreacted within the molecule is present at the terminal end of the molecule or at other sites is used as an alternative. Obtained: A silicone resin in which unreacted hydroxyl groups are present in the molecular ladder structure can become a thermosetting resin. Therefore, when this resin is applied onto a processed layer in a resist process and heated for evaporation of the solvent, that is, for film formation, it is easily hardened by the heating and can no longer be used as a pattern forming material. It has also been proposed to carry out the evaporation of the solvent at low temperatures, but this is undesirably time consuming. Silicone resins of the type described above are also thermally unstable and therefore unsuitable for long-term storage.

As can be understood from the above explanation, unreacted hydroxyl groups remain in the molecule of silicone resins with a ladder structure synthesized by synthesis of trifunctional siloxanes, and this causes the resin to be removed during the resist process. After applying a resist solution of It becomes unusable as a resist. The present invention solves the problems of conventional silicone resins and
The present invention aims to provide an improved thermally stable pattern forming material that can completely prevent the condensation reaction of unreacted hydroxyl groups that may occur even at veribake temperatures below.

Means for Solving the Problems As a result of research to solve the above-mentioned problems, the present inventors have found that
After synthesizing polysilsesquioxane, a silicone resin with a ladder structure, by condensation of trifunctional si-tetraxane,
It is best to remove unreacted hydroxyl groups remaining at the terminal end and/or other parts of the molecule by silylation with a suitable silylating agent, such as a monohalogenated silane, such as trimethylchlorosilane. I found out.

In the present invention, the ladder-structured polysilsesqui:J''xane obtained by condensation of hexafunctional si-tetraxane can be generally represented by the following formula: (In the above formula, RI R2R6 and R4 are the same or different from each other and and each substituted or unsubstituted alkyl group, such as a methyl group, a chloromethyl group, an ethyl group,
or a substituted or unsubstituted teryl group; N represents a phenyl group, a chlorophenyl group, a tolyl group, etc.; ) The weight average molecular weight is preferably 3000 to 10.0000.

According to the present invention, polysilsesquioxane represented by the above formula (V) and having an unreacted hydroxyl group in the molecule is converted into a silylating agent represented by the following formula: X H2O-sl-OH3 (VD 1J ( As a result of the silylation (X in the formula is a halogen), the hydrogen of the hydroxyl group contained in the moe and the halogen of the latter can be combined and eliminated in the form of hydrogen halide.

EXAMPLES The examples set forth below serve to further illustrate the invention.

Example 1: Polymethylsilsesquioxane represented by the above formula (CTV) was synthesized through hydrolysis and condensation of methyltrichlorosilane. This polymer has a molecular weight of 20,000 and contains unreacted hydroxyl groups, so 80C and 1
It was cured by pre-beta for 0 minutes.

Polymethylsilsesquioxane 10 mentioned above? was dissolved in 100W of toluene, 20% of pyridine was added, and 1022% of trimethylchlorosilane was further added dropwise to carry out silylation. The reaction was held at 60C for 2 hours. After the reaction was completed, water 5 (In) was added and water washing was repeated until all the pyridine salt was completely dissolved in the aqueous layer. After water washing, acetonitrile was added until no precipitate was formed. The resulting silylated polymethylsil Sesquioxane was thermally stable and did not harden at all even when baked at 200 C' for 1 hour.

In this example, the silylation reaction is considered to have proceeded as follows: OH5i(GH3-3) A toluene solution was spin-coded onto a silicon wafer to a film thickness of 0.5 μm, and this was coated at 80C for 15 minutes in a nitrogen stream.
Allowed to dry for minutes.

After drying, the silicon wafer was placed in an electron beam exposure device, and a pattern was drawn by irradiating the silicon wafer with an electron beam at an acceleration voltage of 20 KV. This was immersed and developed for 1 minute using a M to K developer. A pattern of 0.5 μm line% space was obtained. Sensitivity 7. OX10-'O/d0 Example 2: The procedure described in Example 1 above was repeated. However, in the case of this example, low molecular weight (molecular weight 40
00) polymethylsilsesquioxane was used. The obtained silylated polymethylsilsesquioxane did not harden at all even after baking for 1500 and 1 hour as in Example 1 above. Incidentally, before silylation, curing was initiated by 6DC and prebaking for 10 minutes.

In this example, the silylation reaction appears to have proceeded as follows: f 0H3Si01.5)-OH(OH3)3SiO
A A toluene solution of polymethylsilsesquioxane (molecular weight 4000, dispersity 1.2) silylated as described above was spin-coated onto a silicon wafer so that the film thickness was 0.5 μm, and this was then heated with nitrogen. 15 at 80C in airflow
Allowed to dry for minutes.

After drying, the silicon wafer was placed in an electron beam exposure device, and a pattern was drawn by irradiating the silicon wafer with an electron beam at an acceleration voltage of 20 V. This was immersed and developed for 1 minute using a M to K developer. A pattern with a 0.3 μm line number space was obtained. Sensitivity: 4.0 x 1 o-s O/Cft0 Effects of the Invention According to the present invention, residual hydroxyl groups can be removed from the silicone resin obtained by condensation of trifunctional siquaxane. A thermally stable pattern can be formed while taking advantage of sensitivity, high resolution, and high dry etching resistance. Further, according to the present invention, the resist solution can be prebaked in the resist process without worrying about temperature and time.

According to the present invention, silicone resins containing many unreacted hydroxyl groups can also be easily used after silylation.

Claims (1)

[Claims] 1. A pattern-forming material consisting of a polysilsesquioxane obtained by condensing a hexafunctional si-tetraxane and removing by silylation the intramolecular hydroxyl groups left unreacted after the condensation reaction. 2. The silylation agent is a monohalogenated silane,
A pattern forming material according to claim 1.