JPS6296526A - Alkali-soluble polyorganosilsesquioxane polymer - Google Patents

Abstract

PURPOSE:To obtain an alkali-soluble polymer excellent in oxygen resistance and extremely useful as a functional polymeric material such as photosensitive or radiation-sensitive material, by using a specified polyorganosilsesquioxane polymer as a component. CONSTITUTION:An alkali-soluble polyorganosiloxane polymer which is a polyorganosilsesquioxane of formula I (wherein R1 and R2 are each an organic group and n is a degree of polymerization) and at least 40% of R1's and R2's are organic groups having a phenolic hydroxyl group. n is usually 8-200. Examples of R1 and R2 include 1-6C (the carbonations of a substituent are excluded) alkyls having phenol or cresol as a substituent, such as formulas II and III. Said polymer can be synthesized by first synthesizing a polyorganosilsesquioxane in which the hydroxyl groups are protected from the corresponding trichlorosilane or trialkoxysilane and removing the protective groups.

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 polyorganosilsesquioxane polymer represented by general formula (1).

[Background of the invention]

Microfabrication technology by etching using light and radiation is used to manufacture electronic components such as semiconductor elements and integrated circuits, and currently resist materials such as phenolic resin and polyvinyl phenol are used because they have excellent resolution. Can alkaline be used? Alkaline-developable resist materials containing a soluble polymer as a basic polymer are the mainstream. For example, a composition of novolac resin and 1,2-naphthoquinone diamides is a positive photoresist, and a composition of polyvinylphenol and bisazides is a negative photoresist. Furthermore, it is widely known that a composition of novolak resin and polyolefin sulfone is a radiation-sensitive positive 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.

Conventional alkali-developable resist materials have metal or metal oxide films as bases (e.g. aluminum, silicon).

It exhibits strong resistance to halogen-based plasma used when the underlying material is an organic material (e.g., a lower flattening film in a two-layer resist method, an insulating film between the eyebrows such as polyimide, etc.). The resistance to oxygen plasma was not sufficient, and there was a strong desire to improve its properties.

Note that the literature on alkali-developable resists includes J.C.
, 5trieter: Kodak Microelectronics Seminar Proceedings (Kodak M
icroelectronicsSen+1nor P
116 (1976), etc.

[Purpose of the invention]

An object of the present invention is to provide an alkali-soluble polymer with excellent oxygen resistance, which can be used as an alternative to the basic polymer of the conventional alkali-developable resist, which has low oxygen plasma resistance.

[Summary of the invention]

Organosilicon polymers are well known as polymers with excellent oxygen plasma resistance. This is because the organosilicon polymer efficiently turns into a silicon oxide film by oxygen plasma, and this silicon oxide film functions as an oxygen plasma resistant film. On the other hand, as an alkali-soluble polymer,
Polymers having phenolic hydroxyl groups, such as Nopola-Tsuku resin and polyvinylphenol, are known.

Therefore, in order to achieve the above objective, we synthesized various polymers whose main chain is polysilsesquioxane which is closest to the structure of silicon oxide and which has a phenolic hydroxyl group in the side chain. An organosilsesquioxane polymer (provided that R,,R in the general formula fil
2 are the same or different organic groups, n is the degree of polymerization).

It has also been found that a polyorganosilsesquioxane polymer containing 40% or more of organic groups having phenolic hydroxyl groups as R+ and Rz is good.

In addition, n is 8 to 200, and R,, R, specifically,
For example, an alkyl group having 1 to 6 carbon atoms (excluding the substituent carbon) having a phenol or the like as a substituent, and the like.

On the other hand, other side chains include the hydroxyl group of the organic group having the phenolic hydroxyl group mentioned above and the alkoxy group.

Examples include L-butyldimethylsiloxy groups, groups protected in the form of methylene acetal, and the like.

Further, in order to make the material soluble in alkali, sufficient alkali solubility cannot be obtained unless organic groups having a phenolic hydroxyl group are present in 40% or more of the total side chains.

The polymer of the present invention is obtained by first synthesizing a polyorganosilsesquioxane with a protected hydroxyl group from the corresponding trichlorosilane or trialkoxysilane, and then preserving the polyorganosilsesquioxane. !
Synthesized by removing the group. The corresponding trichlorosilane or trialkoxysilane can be prepared by various methods,
For example, the Grignard reaction, halides (benzyl chloride derivatives, etc.) and HS i CI! 3 using a tertiary amine and a copper salt, or H5iCj! using a platinum catalyst on a styrene derivative. , etc. can be used.

The synthesis of polyorganosilsesquioxanes with protected hydroxyl groups is described in Journal of the American Chemical Society (J, Am, Chew, 5oc-) + Hama, 6194 (1960), Journal of American Chemical・Society (J, ^-, Chea
p, Soc, ) + Nail, 4317 (1965),
Special Publication Showa 40-15989. Japanese Patent Publication No. 53-88099.
Methods such as JP-A-59-66422 and improved methods have been investigated, but in all methods, the degree of polymerization (
n) is in the range of 8 to 200, and the synthesis method is not limited, and there are various methods for removing the protecting group. For example, from an alkoxy group to a hydroxyl group, use trimethylsilyl iodo, - A method using tetra-n-butylammonium fluoride from a butyldimethylsiloxy group, A method using phosphorus pentachloride from a methylene acetal, etc., and all of these methods were applicable to the synthesis of this polymer. Therefore, in synthesizing the polymer of the present invention, the method for removing the protecting group is not limited.

While the polymer of the present invention is soluble in alkaline water, it is also easily soluble in general-purpose organic solvents, such as alcohol-based, ether-based, amide-based, ketone-based, ester-based, and cellosolve-based organic solvents. The film can be formed using a solution of

Therefore, like conventional alkaline development resists, if this polymer is used as a basic polymer and various photosensitive dissolution inhibitors or radiation-sensitive dissolution inhibitors are selected, this polymer can be used as a base polymer for light or radiation. It can be made into a resist material.

On the other hand, the film of the polymer of the present invention showed extremely high dry etching resistance without peeling at all in oxygen plasma. Therefore, the resist described above can be used as an oxygen plasma resistant film when dry etching the underlying organic substance using oxygen plasma, that is, 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 these Examples.

Example 1 Poly(p-hydroxybenzylsilsesquioxane-
Co-p-methoxybenzylsilsesquioxane) 1.1 Synthesis of p-methoxybenzyltrichlorosilane 2I equipped with a stirrer, a reflux tube, a dropping funnel and a thermometer.
! In a three flask, add 30g of magnesium powder (1,2
gatom), silicon tetrachloride 170g (1,00m
oj2) and diethyl ether 500++/! Put in. After cooling the flask to below 10°C, add 100 g of p-methoxybenzyl chloride (0,63
9moJ) and diethyl ether 200mJ! dropwise over 4 hours. After aging for a further 1 hour at room temperature, excess magnesium and magnesium chloride are removed by suction filtration. The filtrate was vaporized to obtain 44.0 g (0,172 moji!) of the desired product. Yield 26
．． 9% Boiling point 117.5-119.5℃/3.0++
unHg NMR spectrum (60MHz.

CC1a, CHxClz δ5.33) 62.9
1 (2H, s).

3.90 (3H, s), 6.91 (2H, d,
J=8Hz).

7.20 (2H, d, J-8Hz).

1.2 Synthesis of poly(p-methoxybenzylsilsesquioxane) 100mj equipped with 1 magnetic bar, dropping funnel and reflux tube
! In a Mitsuro flask, add 1 g of sodium hydrogen carbonate (0,
13++v+offi) and water 40mj! 10.23g (40,00+nIIIoj!) of p-methoxybenzyltrichlorosilane and 10mj! of diethyl ether were added to the zero dropping funnel. After the completion of the reaction, the reaction mixture was extracted with ether and dried over sodium sulfate. Diethyl ether was distilled off under reduced pressure to obtain 5.10 g of a hydrolysis product. NMR spectrum (60MHz, CDCll5.CH
zCIlzδ5.33)δ2.03 (2H,br,s
), 3.80 (3H, br, s).

6.80 (4H, br, s) IR spectrum (!/
C1-') 3400, 2950.2B50.1610.
1510.1460.1300゜1250, 1180.
1090.1035.890.835.790.760
4.80 g of the hydrolyzed product obtained above with a weight average molecular weight of 2,000° and 1 g of LoHt% methanol solution of potassium hydroxide 49I were added to 25 tal
After the reaction is completed, the reaction mixture is placed in an eggplant flask and heated at 200° C. for 2 hours, and the reaction mixture is dissolved in benzene and dropped into methanol to precipitate a solid.

After filtration, it was dried under reduced pressure to obtain 4.00 g of poly(p-methoxybenzylsilsesquioxane). NMR spectrum (60 MHz, CDCl1z, CHtCIlt
δ5.33) δ1.91 (2H, br, s)
, 3.78 (3H.

br, s), 6.73 (4H, br, s) IR spectrum (cm-') 2950.2850.161
5.1515.1465°1305, 1250.119
5.1120.1040.840.800.770゜Weight average molecular weight 3,300゜1.3 Synthesis of poly(p-hydroxybenzylsilsesquioxane-〇〇-p-methoxybenzylsilsesquioxane) Reflux tube Add poly(
p-methoxybenzylsilsesquioxane) 3.73g
(MeOCaHsCHzS 21.
6ma+on and chloroform 20mj! and trimethylsilyl iodide 6.92g (34,6snoj!)
and stirred with a magnetic rod at 70°C for 22 hours. At room temperature, 20 mJ of methanol was added, and after further stirring for 30 minutes, low-boiling substances were distilled off under reduced pressure, and the residue was extracted with a mixed solvent of diethyl ether and tetrahydrofuran. The extracted solution is washed with an aqueous solution of hydrogen sulfite, an aqueous solution of sodium bicarbonate, and a saline solution, and then the solvent is distilled off under reduced pressure. The obtained polymer was reprecipitated with acetone/hexane and dried under reduced pressure under heat to obtain 2.71 g of the desired product, which had a weight average molecular weight of 4,000. Hydroxyl group content 85%,
NMR spectrum (60MHz, DMS
O-d,, δ5.68) δ1.75 (2H, br
, s), 3.63 (-OCHz, br,
s), 6.58 <4H,br,s), 8.8
8 (-OH, br, s), IR spectrum (ycm-
') 3350, 1620.1515.1450.124
0.11B5.1120°1040, 840.805.
The 760° hydroxyl group content can be controlled by the amount of trimethylsilyl iodide or reaction time. For example, using 1.6 equivalents of trimethylsilyl iodide, methoxy groups were converted to hydroxyl groups in a reaction time of 39% at 4 hours, 54% at 7 hours, 75% at 12 hours, 95% at 48 hours, and almost quantitatively at 72 hours. I was able to convert it. The hydroxyl group content was determined by conducting the reaction in deuterated chloroform and tracking the process of converting methoxy groups into trimethylsiloxy groups using NMR spectroscopy.

1.4 Solubility As a result of examining the solubility of the polymer of the present invention using typical general-purpose organic solvents, it was found that the present polymer having a hydroxyl group content of 50% or more was dissolved in methanol, tetrahydrofuran, N,N-dimethylacetamide, 2 - It dissolved in methylcyclohexanone, isoamyl acetate, ethyl cellosolve, and dimethyl sulfoxide, but was insoluble in toluene and hexane carbon tetrachloride. On the other hand, in the aqueous solution, it was dissolved in an aqueous tetramethylammonium hydroxide solution.

1.5 Oxygen plasma resistance An 8% by weight 2-methylcyclohexanone solution of the polymer of the present invention was applied onto a silicon substrate by a spin coating method, and baked at 100°C for 30 minutes.
．． A coating film with a thickness of 2 μm was formed. Next, oxygen plasma (
Conditions: 0□pressure 0.5 Torr.

Although exposed to RF300W (barrel type asher) for 20 minutes, this polymer did not peel off at all.

〔Effect of the invention〕

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 aqueous solutions, so it can be used as a base polymer for various photosensitive dissolution inhibitors or photosensitive dissolution inhibitors. A composition with a radioactive dissolution inhibitor can be used as a resist material for light or radiation corresponding thereto. On the other hand, since this polymer has excellent oxygen plasma resistance, these resists can be used as an upper layer resist in a two-layer resist method. As described above, the polymer of the present invention is extremely useful as a functional polymer material such as a light- and radiation-sensitive material.

Agent Patent Attorney Masami Akimoto Procedural amendment (voluntary) May 12, 1986

Claims (1)

[Claims] 1. A polyorganosilsesquioxane polymer represented by the following general formula (1), which has ▲a numerical formula, a chemical formula, a table, etc.▼(1) (However, general formula (1) (R_1 and R_2 are the same or different organic groups, and n is the degree of polymerization). An alkali-soluble polyorganosilsesquioxane polymer characterized by containing 40% or more of an organic group having a phenolic hydroxyl group as R_1 and R_2. 2. R_1 and R_2 in the above general formula (1) are p-hydroxybenzyl group and p-methoxybenzyl group,
The alkali-soluble polyorganosilsesquioxane polymer according to claim 1, wherein n is 8 to 200.