JPH0443361A - Organic silicon polymer resist and production thereof - Google Patents

Abstract

PURPOSE:To avert the degradation in definition by substituting the hydrogen atom of a silanol group contained in the polymer with a specific triorganolsilyl group. CONSTITUTION:The hydrogen atom of the silanol group contained in the org. silicon polymer expressed by formula I is substd. with the triorganolsilyl group expressed by formula II. In the formulas I, II, R<1> denotes (CH2)L-COOH, etc.; L denotes 1 to 10; m denotes 0 to 10 integer; n denotes 10 to 50,000 integer; R denotes a lower alkyl group or aryl group which may be the same or different. The practicable use of the org. silicon polymer resist for which an aq. alkaline soln. is usable as a developer is enabled in this way and the formation of submicron patterns is possible.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a negative resist for ionizing radiation, and aims to form a fine pattern that does not cause a decrease in resolution due to swelling during development. [Field of Industrial Use] The present invention relates to organosilicon polymer resists with excellent resolution.

Due to the need to process a large amount of information at high speed, the integration of semiconductor devices forming the main body of information processing equipment has progressed, and LSI and VLSI have been put into practical use, and this integration is continuing to improve further.

Since integration is achieved by miniaturizing unit elements, the minimum width of the wiring pattern is submicron (Su
b-micron).

Further, since integration involves crossing wiring patterns, a step of 1 to 2 μm is often formed on the surface of the semiconductor substrate.

In order to form a fine pattern, a resist is coated on the substrate to be processed, and the resist is selectively irradiated with ultraviolet rays through a mask, etc., and the exposed area becomes soluble in the developer (positive type), or A resist pattern is created by utilizing the difference in solubility between becoming insoluble (negative type) and
Photolithography is used to perform dry etching using this as a mask to form fine patterns.

[Conventional technology]

With the miniaturization of semiconductor integrated circuits, the light sources used in photoetching technology have replaced conventional ultraviolet rays with 1tI% light sources such as far ultraviolet rays, electron beams, and X-rays with shorter wavelengths due to limitations in resolution due to wavelength. As No. 11 radiation came to be used, high resolution was also required for resists, and polychloromethylstyrene and the like have conventionally been used as negative resists.

However, it is difficult to form fine patterns when the substrate surface has a step difference, and a two-layer resist has been proposed as a method to solve this problem.

That is, there is a method in which a lower layer resist made of phenol novolac resin or cresol novolac resin is applied to a thickness of 1 to 5 μm to flatten the step, and then an upper layer resist is formed thereon with a thickness of ff<(0,1 to 1 μm). It has started to be adopted.

This method involves forming a pattern on the upper resist layer by performing selective exposure and development, and then anisotropically etching the lower resist layer using oxygen (0,) plasma using this pattern as a mask to obtain a resist pattern.

The two-layer resist method allows the upper layer resist to be made much thinner than the single-layer resist method, and thus can achieve high resolution.

knee, upper layer resist is 0. It is necessary to have sufficient resistance to plasma, and from this point of view, silicone-based resins or St-containing organic resins are being considered.

For example, poly P-chloromethylphenylphenylsiloxane, polyallylsilsesquioxane.

Polyvinylsilsesquioxane and the like.

However, since these organosilicon polymer (silicone) resists must be developed using an organic solvent after exposure, swelling is unavoidable, resulting in a problem of reduced resolution.

[Problem to be solved by the invention]

Organosilicon polymer resists, which are suitable as upper layer resists for two-layer resists, undergo severe swelling due to the need to use organic solvents to develop the latent image generated by exposure, which makes it difficult to create submicron fine patterns stably. Cannot be formed.

Therefore, it is an issue to put into practical use a resist that does not reduce resolution due to swelling during development.

[Means to solve the problem]

The above problem is an organosilicon polymer represented by the following general formula (1), in which the hydrogen atoms of the silanol groups contained in the polymer are substituted with triorganosilyl groups represented by the following formula (2). This problem can be solved by constructing an organic silicon polymer resist.

[R1-5iOs/z) n...(
1) R3Si-...(2) However, R1 is (CTo) t-C0OH or (CHz)m
-・;;:;No C00H1 is 1 to 10. m is O~10
The integer n is an integer of 10 to 50,000, and R is a lower alkyl group or an aryl group, which may be the same or different. , alkali, and R1 in formula (1), which takes a ladder structure to enable development, is (C
Hz) L-COOI group or (CH2)-
A compound having a carboxy group like the I group is used.

In this way, the polymer can be made alkali soluble, thereby minimizing swelling of the resin,
Therefore, it becomes possible to form submicron patterns.

Note that precautions to be taken in manufacturing this resist according to the present invention are as follows.

Constituting R1 (CHz) L-COOI (L is 1~
It takes an integer of 10, but preferably takes a value of 1 to 5 because the higher the content of Si atoms in the entire polymer, the better the resistance to Ox plasma.

In addition, m of (CHri1Il-q-Cool() is 0 to 10
It is preferably an integer of 0 to 5.

Further, n in formula (1) may be any integer in the range of 10 to so, ooo, but preferably takes a value of 10 to 1000.

Also, R”-5i R33... (3), R2
is (CHI) t X or (CHz) m-t'g, -
It is a halogenated hydrocarbon represented by the general formula of It is preferable that there be.

Further, R2 may be used alone or in combination of two or more.

In addition, R3 may be any hydrolyzable substituent, such as a halogen or methoxy group such as CI,
Lower alkoxy groups such as ethoxy groups are advantageous.

These compounds are reacted with water to be hydrolyzed, followed by dehydration condensation polymerization, (R1-5i0,7□], ... (4
), but in this case, in order to suppress gelation due to violent random reactions, if R3 is a halogen, the reaction should be carried out gradually at a low temperature, and if necessary, an acid catalyst or a base may be used. A catalyst may also be used.

Furthermore, in order to improve the stability of the polymer, it is necessary to silylate and seal the silanol groups that did not contribute to the reaction.

Also, the value of n in equation (4) is 1 as in equation (1).
Any integer within the range of 0 to so, ooo may be used, but 10 to 1000 is appropriate.

That is, when n<10, the coverage decreases;
If it is >50,000, it becomes difficult to synthesize the polymer, and there are problems such as increased viscosity.

Next, [R1-5i037□]7 ・
...In (8), the value of m of (CHz)mMg 0 to 5 is preferable, and 0 to 3 is particularly preferable because it has excellent properties.

Further, the value of n may be any integer within the range of 10 to 50,000, but is suitably 10 to 1ooo.

Further, when carrying out the Grignard reaction, in order to improve the yield, it is preferable to carry out the reaction in a system in which water is extremely excluded.

Note that the reaction between the Grignard compound and CO3 is COt
This can be done by blowing dry ice into the reaction system, or by pouring dry ice into the reaction system.

After reaction with Cot, the polymer is obtained as Mg salt of carboxylic acid, but by treatment with acid [R1-5i
Oszt ) A...(1) A polymer as shown by the formula (1), in which the terminal and the silanol group in the polymer are R55i-...(2) A polymer shown by the formula (2) Polymers substituted by triorganosilyl groups can be obtained.

Next, in order to use such a polymer as a resist, it is preferable to refine it as necessary and subject it to molecular weight fractionation before use.

To form a resist, this organosilicon polymer is dissolved in an appropriate solvent and then spin-coded onto the substrate to be processed.
! It is selectively exposed to radiation by irradiating it with radiation, but in this case, the exposed area undergoes a crosslinking reaction and becomes insoluble in the solvent.
The unexposed area has residual carboxyl groups and is therefore soluble in an alkaline aqueous solution, making it possible to obtain a negative pattern.

〔Example〕

Synthesis example 1: 500cc of methyl isobutyl ketone, 40cc of pyridine
The mixed system was cooled to -70°C with stirring, and added dropwise to chloromethylphenylethyl trichlorochloride.

After that, 100g of pure water was gradually added dropwise, and after dropping,
．． The temperature was raised at a rate of 5°C, and the mixture was stirred at 85°C for 10 hours.

After cooling, the mixture was allowed to stand, the aqueous layer was removed, and the mixture was thoroughly washed with water.

Next, after concentrating the solution using a rotary evaporator, a large amount of acetonitrile was added to precipitate the polymer.

Then, add 500 g of methyl isobutyl ketone to this polymer.
100 cc of pyridine was added thereto, cooled to 0''C, and 100 cc of trimethylchlorosilane was gradually added dropwise while stirring.

After the dropwise addition, the system was heated to 80°C and stirred for about 4 hours.

Next, after cooling, water was added to the system to dissolve the precipitated salt.

Next, the aqueous layer was removed, and the mixture was further washed with water three times, and a large amount of water was added to the reaction solution to precipitate a polymer.

After purification and drying, 30'g of this was dissolved in dry ethyl ether and poured into metallic Mg.

Next, this solution was poured onto 200 g of finely crushed dry ice, and 100+nl of 5N HCl was added to the polymer. Carboxylic acid was added to the polymer, and a polymer soluble in an alkaline aqueous solution was obtained.

Synthesis Example 2: 95 g of tetraromethyltrichlorosilane was dissolved in methyl isobutyl ketone and cooled to -70°C with stirring.
Next, drop concentrated HCN very slowly, then add 100ml of pure water.
1 was gradually added dropwise.

The operation after dropping was performed in the same manner as in Synthesis Example 1 to obtain a polymer soluble in an alkaline aqueous solution.

Example 1: A phenol novolak resin was applied to a thickness of 1.5 mm on a Si substrate, and heated and dried at 200°C to form a lower resist layer.

Next, a resist solution obtained by adjusting the viscosity of the polymer obtained in Synthesis Example 1 with a solvent was spin-coated and applied to a thickness of 0.3μ■, heated to 80°C and dried, and the upper layer resist was formed.

Next, after performing electron beam exposure and developing with an alkaline aqueous solution (tetramethylammonium hydroxide),
．． Reactive ion etching (RIE) using gas
The lower layer resist was etched.

As a result of observing this pattern with a scanning electron microscope photograph, it was found that 0
．． It was able to resolve lines and spaces of 3 μm.

Example 2: A phenol novolac resin was coated on a Si substrate to a thickness of 1.5 μm steel, and heated and dried at 200° C. to form a lower resist.

Next, a resist solution obtained by adjusting the viscosity of the polymer obtained in Synthesis Example 2 with a solvent was spin-coated and applied to a thickness of 0.3μ, heated to 80°C and dried, and the upper layer A resist was formed.

Next, X-ray exposure was performed through a mask, development was performed with an alkaline aqueous solution (tetramethylammonium hydroxide), and reactive ion etching (
RIE) was performed to etch the lower resist layer.

As a result of observing this pattern with a scanning electron micrograph,
It was possible to resolve lines and spaces of 0.3μ.

〔Effect of the invention〕

By carrying out the present invention, it is possible to put into practical use an organosilicon polymer resist that can use an alkaline aqueous solution as a developer.
This makes it possible to form submicron patterns.

Claims (2)

[Claims] (1) An organosilicon polymer represented by the following general formula (1), in which a hydrogen atom of a silanol group contained in the polymer is substituted with a triorganosilyl group represented by the following formula (2). An organosilicon polymer resist [R^1-SiO_3_/_2]_n...(1)R_
3Si-...(2) However, R^1 is (CH_2)_L-COOH or (CH_2
)_m-■-COOH L is an integer of 1 to 10, m is an integer of 0 to 10, n is an integer of 10 to 50,000, R is a lower alkyl group or an aryl group and may be the same or different, (2) The silicone resist according to claim 1 is obtained by reacting an organosilicon compound represented by the following general formula (3) with water and hydrolyzing it, and subjecting the resulting reaction product to dehydration condensation polymerization, An organosilicon polymer represented by formula (4) is prepared, and then a triorganosilane represented by the following formula (5) and a triorganosilane represented by the following formula (5) are prepared.
6) Hexaorganodisilazane represented by the formula, the following (7
) or a mixture thereof to replace the hydrogen atoms of the silanol groups remaining in the polymer with the triorganosilyl group shown in the above formula (2), and then The organosilicon polymer is then reacted with magnesium to obtain an organosilicon polymer represented by the following formula (8), and after reacting with carbon dioxide, the organosilicon polymer is treated with an acid to produce an organosilicon polymer represented by the above formula (1). A method for producing an organosilicon polymer resist, characterized in that a hydrogen atom of a silanol group contained in the polymer is substituted with a triorganosilyl group represented by the above formula (2). R^2-SiR^3_3...(3) [R^2-SiO_3_/_2]_n...(4)R_
3SiY...(5) (R)_3SiNHSi(R)_3...(6)(R)
_3SiOSi(R)_3...(7) [R^4-Si
O_3_/_2]_n...(8) However, R^2 is (CH_2)_LX or (CH_2)_m-
-X, where X is a halogen, L is an integer of 1 to 10, m is an integer of 0 to 10, R^3 is a halogen or a lower alkoxy group, and R is a lower alkyl group or an aryl group, which may be the same or different. , Y is a halogen, cyano group, isocyanato group or isothiocyanato group, R^4 is represented by the general formula (CH_2)_mMgX,
is a halogen, and m is an integer of 0 to 10.