JPH0558447B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a novel polymer that is extremely useful as a functional polymer material such as a light- and radiation-sensitive material. More specifically, the present invention relates to an alkali-soluble silmethylene polymer comprising a structural unit represented by the following general formula (1).

General formula (1) (However, in general formula (1), R ₁ and R ₂ are alkyl groups,
R ₃ represents hydrogen, R ₄ represents an alkyl group, the number l of OH groups and R ₄ groups is 1 or 2, arbitrary positions of the benzene ring, m and n are 2 to 200, n/(m+n) is
It is 0.4 or more. ) [Background of the Invention] Microfabrication technology by etching using light and radiation is used in the production of electrical parts such as semiconductor elements and integrated circuits, and currently the resist material for this is excellent in sensitivity. Alkaline-developable resists containing an alkali-soluble polymer such as phenolic resin or polyvinylphenol as a basic polymer are the mainstream. For example, it is widely known that a composition of novolak resin and o-quinonediazides is a positive resist, and a composition of polyvinylphenol and bisazides is a negative resist. On the other hand, as the wiring of semiconductor devices and the like becomes finer, dry etching is increasingly being used instead of the conventional wet etching for etching the underlying layer after patterning the resist layer. Therefore, resist materials are required to have strong resistance to dry etching.
For example, when the underlying material is organic, it is etched by oxygen plasma, but conventional resist materials have poor resistance to oxygen plasma, and there has been a strong desire to improve their properties. In addition, as for literature on alkali-developable resists, J.C. Strieter: Kodak Microelectronics Seminar Proceedings (JC Strieter: Kodak
Microelectronics Seminar Proceedings）116
(1967), etc.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide an alkali-soluble polymer with excellent oxygen plasma resistance.

[Summary of the invention]

Organosilicon polymers are well known as polymers with excellent oxygen plasma resistance. this is,
This is because the organosilicon polymer efficiently turns into a silicon oxide film by oxygen plasma, and this silicon oxide film acts as an oxygen plasma resistant film. On the other hand, as alkali-soluble polymers, polymers having phenolic hydroxyl groups such as novolac resins and polyvinylphenol are known. Therefore, in order to achieve the above object, the present inventors synthesized various polymers having a silmethylene skeleton in the main chain and a phenolic hydroxyl group in the side chain, and found that the following general formula (1)
It has been found that a polymer consisting of a structural unit represented by the following formula satisfies the above object.

General formula (1) Here, R ₁ and R ₂ in general formula (1) are alkyl groups,
Preferably, it represents a _C1 - _C6 alkyl group, _R3 represents hydrogen, and _R4 represents an alkyl group, preferably a _C1 - _C6 alkyl group. The number l of O groups and OR ₄ groups is 1 or 2, and may be located at any position on the benzene ring. m
and n is a positive integer, m+n is 2 to 200,
To make it alkali soluble, n/(m+n)
Must be 0.4 or higher.

The polymer (1) of the present invention generally has the formula (2),
Synthesized according to formula (3), formula (4) and formula (5).

Here, X ₁ is a halogen or alkoxy group,
X ₂ represents a halogen, and M represents a metal. First, in formula (2), a monohalogenosilane or monoalkoxylane (c) is synthesized using a dihalogenosilane or dialkoxylane (a) and a Grignard reagent (b). Then, in formula (3), the benzyl hydrogen of (c) is halogenated to obtain (d). At this time, photochlorination, N-
Chlorosuccinimide, N-bromosuccinimide, etc. can be used. In formula (4), (d) is polymerized using a metal to form (e). Magnesium and alkali metals are used as metals. When magnesium is used, the polymer skeleton is arranged in the order of Si and C, but when an alkali metal is used, the polymer skeleton has Si-Si bonds and C.
-C bond also comes in. Therefore, the polymer skeleton of general formula (1) has a structure that includes not only Si--C bonds but also Si--Si bonds and C--C bonds. Finally, in formula (5), the OR ₄ group is converted. For the cleavage of the protecting group, various reactions such as trimethylsilyl iodo/methanol can be used. In addition, from the beginning, silyl groups with large steric hindrance such as t-butyldimethylsilyl group are used.
It is also possible to protect the OH and remove it with acid in the final step.

The polymer of the present invention is soluble in alkaline water, such as an aqueous tetramethylammonium hydroxide solution, while being soluble in general-purpose organic solvents, such as alcohols, ethers, amide, ketones, esters, cellosolves, etc. Since it is easily dissolved in organic solvents, films can be formed using these solutions.

Therefore, like conventional alkaline development resists, this polymer can also be used as a positive photoresist when combined with o-quinonediazides, and as a negative photoresist when combined with bisazides. Furthermore, this polymer has
It is also used as a positive radiation resist in combination with poly(olefin sulfone).

On the other hand, since the polymer of the present invention does not deteriorate at all in oxygen plasma and exhibits extremely high dry etching resistance, the above resist can be used as an upper layer resist in a two-layer resist method.

[Embodiments of the invention]

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the Examples.

Example 1 Poly(1,1-dimethyl-2-p-methoxyphenylsilmethylene-co-1,1-dimethyl-2-p-hydroxyphenylsilmethylene) 1-(1) Synthesis of chlorodimethyl-p-methoxybenzylsilane In a two-three-neck flask equipped with a stirrer, reflux tube, dropping funnel, and thermometer, add 31.0 g (1.28 mol) of magnesium powder and dimethyldichlorosilane.
129g (1mol) and 500ml diethyl ether
Put in. After cooling the flask to below 10℃,
p-methoxybenzyl chloride from the dropping funnel 100
A mixture of g (0.639 mol) and 250 ml of diethyl ether was added dropwise over 4 hours. 1 more at room temperature
After aging for an hour, excess magnesium and magnesium chloride are removed by suction filtration. The filtrate was distilled to obtain 87.8 g (0.409 mol) of the target product. The yield was 64.0%, and the boiling point was 80°C/1mmHg.
In addition, NMR spectra (60MHz, Cl ₄ , CH ₂ Cl ₂ ,
δ5.33) is δ0.46 (6H, S), 2.40 (2H, S),
3.83 (3H, S), 6.82 (2H, d, J = 9.0Hz),
7.80 (2H, d, J = 9.0Hz), and the IR spectrum (νcm ^-1 ) is 2970, 1620, 1520, 1475,
1310, 1260, 1195, 1090, 1055, 855, 825,
It was 780.

1-(b) Synthesis of bromo-p-methoxyphenylchlorodimethylsilylmethane (dl) In a 500 ml three-necked flask equipped with a stirrer and reflux tube, add 43.2 g (0.200 mol) of chlorodimethyl-p-methoxybenzylsilane and carbon tetrachloride.
Add 200ml. While heating and stirring carbon tetrachloride, add 35.6 g of N-bromosuccinimide.
(0.200mol) is gradually added. After aging for 1 hour, succinimide was removed by suction filtration, and the filtrate was distilled to obtain 31.7 g of the target product.
(0.108 mol) was obtained. The yield was 54.0%. And the boiling point is 113-117℃/2.5mmHg, the melting point is 30
It was below ℃. In addition, the NMR spectrum (60MNz, CCl ₄ , TMS) is δ0.50 (3H, S),
0.60 (3H, S), 3.73 (3H, S), 4.32 (1H, S),
6.73 (2H, d, J = 9Hz), 7.19 (2H, d, J =
9Hz), and the IR spectrum (νcm ^-1 ) is
1610, 1510, 1465, 1305, 1260, 1185, 1040,
They were 865, 845, 820, and 800.

1-(3) Synthesis of poly(1,1-dimethyl-2-p-methoxyphenylmethylene) A 500 ml three-necked flask equipped with a Herschberg stirrer, reflux tube, and dropping funnel was purged with nitrogen. 7.6g (0.33g) of sodium in the flask
atom) and 120 ml of toluene, and heat and stir to obtain fine particles of sodium. While stirring toluene under reflux, add 44.1 g of bromo-p-methoxyphenylchlorodimethylsilylmethane.
A mixture of (0.15 mol) and 30 ml of toluene was added dropwise over 1 hour. After continuing to mature for 1 hour,
The reaction mixture is poured into methanol to remove excess sodium and precipitate the polymer.
After filtration, the polymer dissolved in tetrahydrofuran is dropped into water to remove sodium salts. The filtered polymer was washed with methanol and dried under reduced pressure to obtain 10 g of the desired product. The yield is
It was 37%. The softening point was 121-125°C, and the weight average molecular weight was 3,400. Also, the NMR spectrum (60MHz, C ₆ D ₆ , CH ₂ Cl ₂ , δ5.33) is δ1.27 (6H, br.s), 4.43 (3H, br.s), 7.4-8.7
(4H, br.s), the methine proton is difficult to identify, and the IR spectrum (νcm ^-1 ) is 2960, 2850,
1610, 1510, 1470, 1385, 1300, 1260, 1100,
They were 1045, 860, and 790. Furthermore, in the Grignard reaction, the weight average molecular weight was about 1000.

1-(4) Synthesis of poly(1,1-dimethyl-2-p-methoxyphenylsilmethylene-co-1,1-dimethyl-2-p-hydroxyphenylsilmethylene) Poly(1,1-dimethyl-2
-p-methoxyphenylsilmethylene) 0.50g
(2.8 mmol in monomer units) and 1.5 ml of chloroform
and trimethylsilyl iodide 0.88g (4.4m
mol) and stir with a magnetic rod. After reacting for 4 hours, 4 ml of methanol was added and stirred for 3 hours. At room temperature, low boilers are distilled off under reduced pressure, and the residue is extracted with ether. The ether solution is washed with an aqueous sodium bisulfite solution, an aqueous sodium bicarbonate solution, and brine, and the ether is distilled off under reduced pressure. The obtained polymer was reprecipitated with tetrahydrofuran/water and dried by heating under reduced pressure to obtain 0.23 g of the desired product. The weight average molecular weight was 1800, the OH content was 100%, and the softening point was 107-113°C. Also
NMR spectrum (60MHz, DMSO-ds,
δ5.68), δ−0.79~0.51 (6H, bs.s), 6.15~7.35
(4H, br.s), methine protons, and hydroxy protons are difficult to identify, and the IR spectrum (ν
cm ^-1 ) are 3380, 2980, 1510, 1270, 1100,
They were 1040, 860, and 810.

Note that the OH content can be controlled by the amount of trimethylsilyl iodide or reaction time.
For example, when a methoxy group is reacted with 1.3 equivalents of trimethylsilyl iodide for a reaction time of 4 hours, 90% of the methoxy group is converted to a hydroxyl group. Also, 70% at 0.80 equivalent and 55 at 0.65 equivalent
%, the conversion rate was 40% at 0.50 equivalent. In addition,
The value of OH content was determined by conducting the reaction in deuterated chloroform and monitoring the process of converting methoxy groups to trimethylsiloxy groups using NMR spectroscopy.

1-(5) Soluble poly(1,1-dimethyl-2-p-methoxyphenylsilmethylene-co-1,1-dimethyl-2-p-hydroxyphenylsilmethylene)
As a result of examining the solubility in typical general-purpose organic solvents, the polymer of the present invention with an OH content of 40% or more was found to be soluble in methanol, tetrahydrofuran, N,N
- It was soluble in dimethylacetamide, 2-methylcyclohexanone, isoamyl acetate, methyl cellosolve, and dimethyl sulfoxide, but insoluble in toluene, hexane, and carbon tetrachloride. On the other hand, in the aqueous solution, it was dissolved in an aqueous tetramethylammonium hydroxide solution.

1-(6) Oxygen plasma resistance 10% by weight of poly(1,1-dimethyl-2-p-methoxyphenylsilmethylene-co-1,1-dimethyl-2-p-hydroxyphenylsilmethylene)2- A methylcyclohexanone solution was applied onto a silicon substrate by a spin-ating method, and baked at 100°C for 30 minutes.
A polymer coating film with a thickness of 0.2 μm was formed. Next, oxygen plasma (conditions: oxygen pressure 0.5 torr, degree of vacuum
10 ^-4 torr, RF300W) for 10 minutes, this polymer did not peel off at all.

〔Effect of the invention〕

As mentioned above, the polymer of the present invention is soluble in general-purpose organic solvents, so it can be formed into a film, and it is also soluble in alkaline water, so the composition with o-quinone diazites can be used in alkaline development positives. A composition of type photoresists with bisazides becomes an alkali-developed negative type photoresist. Furthermore, compositions with poly(olefin sulfone) can also be used as alkaline-developed positive-working electron beam resists. On the other hand, since the polymers of the present invention have excellent oxygen plasma resistance, these resists can be used as upper layer resists in a two-layer resist method. That is, the polymer of the present invention is extremely useful as a functional polymer material such as a light- and radiation-sensitive material.

Claims (1)

[Scope of Claims] 1. An alkali-soluble silmethylene polymer characterized by comprising a structural unit represented by the following general formula (1). general formula (However, in general formula (1), R ₁ and R ₂ are alkyl groups,
R ₃ represents hydrogen, R ₄ represents an alkyl group, the number l of OH groups and R ₄ groups is 1 or 2, arbitrary positions on the benzene ring, m and n are positive integers, m + n is 2
~200, n/(m+n) is 0.4 or more. )