JPH0558446B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a novel polymer 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 phenolic resin is currently used as a resist material for this because it has excellent resolution. Alkaline-developable resist materials containing an alkali-soluble polymer such as polyvinylphenol or polyvinylphenol as a basic polymer are the mainstream. for example,
A composition of novolak resin and 1,2-naphthoquinone diazides is a positive photoresist, and a composition of polyvinylphenol and bisazides is a negative photoresist. Furthermore, it is widely known that a composition of novolac 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 exhibit strong resistance to halogen-based plasma used when the underlying material is a metal or metal oxide film (e.g. aluminum, silicon, silicon oxide film, etc.), but when the underlying material is an organic material (e.g. The resistance to oxygen plasma used in the case of the lower layer planarizing film in the layered resist method, the interlayer insulating film such as polyimide, etc.) is not sufficient, and there has been a strong desire to improve its properties. In addition, as a literature on alkali-developable resists, JC
Written by Strieter: Kodak Microelectronics Seminar Proceedings
Microelectronics Seminar Proceeding) 116
(1976), etc. [Object of the Invention] An object of the present invention is to provide an alkali-soluble polymer having excellent oxygen plasma 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,
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 objective, we synthesized various polymers whose main chain is polysilsesquioxane that is closest to the structure of silicon oxide and which has a phenolic hydroxyl group in the side chain.As a result, we obtained the following general formula (1). A polyorganosilsesquioxane polymer, (However, in general formula (1), R ₁ and R ₂ are the same or different organic groups, and n is the degree of polymerization). And, 40% or more of R ₁ and R ₂ is an alkyl group having 1 to 6 carbon atoms having phenol or catechol as a substituent, and the hydroxyl group of other groups is protected in the form of an alkoxy group or/and a siloxy group. It has been found that a polyorganosilsesquioxane polymer in which n is 8 to 200 is preferable. Specifically, R ₁ and R ₂ are, for example,

【formula】

【formula】

Examples include alkyl groups having 1 to 6 carbon atoms (excluding the carbon atoms of the substituents) having phenol or catechol as a substituent. On the other hand, other side chains include groups in which the hydroxyl group of the above-mentioned phenolic hydroxyl group-containing organic group is protected in the form of an alkoxy group, t-butyldimethylsiloxy group, or methylene acetal. In addition, in order to make it soluble in alkali, organic groups with phenolic hydroxyl groups should be added to the entire side chain.
Sufficient alkali solubility cannot be obtained unless it is present in an amount of 40% or more. The polymer of the present invention is synthesized by first synthesizing a polyorganosilsesquioxane with a protected hydroxyl group from the corresponding trichlorosilane or trialkoxysilane, and then removing the protecting group. The corresponding trichlorosilanes or trialkoxysilanes can be synthesized by various techniques, such as the Grignard reaction, the condensation of a halide (such as a benzyl chloride derivative) with HSiCl ₃ using a tertiary amine and a copper salt, or the condensation of a styrene derivative with platinum. A method of adding HSiCl ₃ using a catalyst, etc. can be used. The synthesis of polyorganosilsesquioxane with protected hydroxyl groups was carried out by the Journal of American Chemical Society (J.Am.Chem.Soc.).
82, 6194 (1960), Journal of American Chemical Society (J.Am.Chem.Soc.),
87, 4317 (1965), Special Publication No. 15989, No. 15989, No. 53-
88099, JP-A No. 59-66422, and improved methods thereof, the degree of polymerization (n) is in the range of 8 to 200 in all methods, and the synthesis method is not limited. do not have. Furthermore, there are various methods for removing the protecting group. For example, there is a method using trimethylsilyl iodo to convert an alkoxy group to a hydroxyl group, a method to use tetra-n-butylammonium fluoride to convert a t-butyldimethylsiloxy group, and a method to use phosphorus pentachloride to convert a methylene acetal group. It could be applied to polymer synthesis. 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, the present polymer will react to the corresponding light or radiation. It can be used as a resist material for On the other hand, the film of the polymer of the present invention did not deteriorate at all in oxygen plasma and exhibited extremely high dry etching resistance. Therefore, the resist described above can be used as an oxygen plasma resistant film when dry etching an underlying organic substance using oxygen plasma, that is, as an upper layer resist in a two-layer resist method. [Examples of the Invention] Hereinafter, the present invention will be specifically explained using Examples, but the present invention is not limited to these Examples. Example 1 Poly(p-hydroxybenzylsilsesquioxane) and poly(p-hydroxybenzylsilsesquioxane-CO-p-methoxybenzylsilsesquioxane) 1.1 Synthesis of p-methoxybenzyltrichlorosilane Stirrer, reflux In a two-three-necked flask equipped with a tube, dropping funnel, and thermometer, add 30 g (1.2 gatom) of magnesium powder and 170 g of silicon tetrachloride.
(1.00 mol) and 500 ml of diethyl ether. After cooling the flask to below 10°C, add 100 g of p-methoxybenzyl chloride from the dropping funnel.
A mixture of (0.639 mol) and 200 ml of diethyl ether was added dropwise over 4 hours. After aging for a further 1 hour at room temperature, excess magnesium and magnesium chloride are removed by suction filtration. 44.0g (0.172mol) of the target product was obtained by distilling the filtrate.
Obtained. Yield 26.9%, boiling point 117.5-119.5℃/3.0mm
HgNMR spectrum (60MHz, CCl ₄ , CH ₂ Cl ₂ ,
δ5.33) δ2.91 (2H, s), 3.90 (3H, s), 6.91
(2H, d, J=8Hz), 7.20 (2H, d, J=8
Hz). 1.2 Synthesis of poly(p-methoxybenzylsilsesquioxane)
In a 100ml three-necked flask, add sodium bicarbonate.
Add 11g (0.13mmol) and 40ml of water. A mixture of 10.23 g (40.00 mmol) of p-methoxybenzyltrichlorosilane and 10 ml of diethyl ether was added dropwise from the dropping funnel over 30 minutes, and the mixture was further aged for 30 minutes. After the reaction is complete, the reaction mixture is extracted with ether and dried over sodium sulfate. Diethyl ether was distilled off under reduced pressure to produce hydrolyzed product 5.10
I got g. NMR spectrum (60MHz, _CDCl3 ,
CH ₂ Cl ₂ , δ5.33) δ2.03 (2H, br.s), 3.80 (3H,
br.s), 6.80 (4H, br.s) IR spectrum (νcm
^-1 ) 3400, 2950, 2850, 1610, 1510, 1460,
1300, 1250, 1180, 1090, 1035, 890, 835,
790, 760. Weight average molecular weight 2000. 25 ml of 4.80 g of the hydrolysis product obtained above and 49 mg of a 10 wt% methanol solution of potassium hydroxide
Place in an eggplant flask and heat at 200℃ for 2 hours.
After the reaction is completed, the reaction mixture is dissolved in benzene,
The solid is precipitated by dropping into methanol. After filtration, dry under reduced pressure to obtain 4.00 g of poly(p-methoxybenzylsilsesquioxane).
I got it. NMR spectrum (60MHz, _CDCl3 ,
CH ₂ Cl ₂ , δ5.33) δ1.91 (2H, br.s), 3.78 (3H,
br.s), 6.73 (4H, br.s) IR spectrum (νcm
^-1 ) 2950, 2850, 1615, 1515, 1465, 1305,
1250, 1195, 1120, 1040, 810, 800, 770. Weight average molecular weight 3300. 1.3 Poly(p-hydroxybenzylsilsesquioxane) and poly(p-hydroxybenzylsilsesquioxane-CO-p-methoxybenzylsil) 3.73 g of poly(p-methoxybenzylsilsesquioxane) (21.6 m in MeOC ₆ H ₅ CH ₂ SiO _3/2 units) was placed in a 100 ml eggplant-shaped flask equipped with a reflux tube.
mol), 20 ml of chloroform, and 6.92 g (34.6 mmol) of trimethylsilyl iodide, and heated to 70°C.
Stir with a magnetic rod for 22 hours. At room temperature, 20 ml of methanol was added, and after stirring for an additional 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 sodium bisulfite solution, an aqueous sodium bicarbonate solution, and brine, and then the solvent is distilled off under reduced pressure. The obtained polymer was reprecipitated with acetone/hexane,
The product was dried under reduced pressure by heating to obtain 2.71 g of the desired product. Weight average molecular weight 4000, hydroxyl group content 85%, NMR spectrum (60MHz, DMSO- _d6 , δ5.68) δ1.75
(2H, br.s), 3.63 (−OCH ₃ , br.s), 6.58 (4H,
br.s), 8.88 (-OH, br.s). IR spectrum (ν
cm ^-1 ) 3350, 1620, 1515, 1450, 1240, 1185,
1120, 1040, 840, 805, 760. The hydroxyl group content can be controlled by the amount of trimethylsilyl iodide or reaction time. For example, using 1.6 equivalents of trimethylsilyl iodide, a methoxy group can be converted to a hydroxyl group almost quantitatively in a reaction time of 4 hours, 54% in 7 hours, 75% in 12 hours, 95% in 48 hours, and 72 hours. Ta. Note that the hydroxyl group content was determined by conducting the reaction in deuterated chloroform and tracking the process in which methoxy groups were converted to trimethylsiloxy groups using NMR spectroscopy. 1.4 Solubility As a result of examining the solubility of the polymer of the present invention in a typical general-purpose organic solvent, the hydroxyl group content was 50%.
The above present polymer contains methanol, tetrahydrofuran, N,N-dimethylacetamide, 2-
It was soluble in methylcyclohexanone, isoamyl acetate, ethyl cellosolve, and dimethyl sulfoxide, but 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 spin coating, and a coating film with a thickness of 0.2 μm was formed by baking at 100°C for 30 minutes. did. Subsequently, oxygen plasma (conditions: O ₂ pressure
0.5Torr, RF300W, barrel type atssia)
Although exposed for 20 minutes, the polymer did not peel off at all. [Effects 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 in various photosensitive applications using this polymer as a basic polymer. A composition with a dissolution inhibitor or a radiation-sensitive dissolution inhibitor can be used as a photo- or radiation-resistant resist material corresponding thereto. On the other hand, since the present polymer has excellent oxygen plasma resistance, these resists can be used as an upper layer resist, etc. 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.

Claims (1)

[Scope of Claims] 1 A polyorganosilsesquioxane polymer represented by the following general formula (1), (However, in general formula (1), R ₁ and R ₂ are the same or different organic groups, and n is the degree of polymerization). And, 40% or more of R ₁ and R ₂ is an alkyl group having 1 to 6 carbon atoms having phenol or catechol as a substituent, and the hydroxyl group of other groups is protected in the form of an alkoxy group or/and a siloxy group. an alkali-soluble polyorganosilsesquioxane polymer, wherein n is 8 to 200. 2. The alkali-soluble polyorganosilsesquioxane according to claim 1, wherein R ₁ and R ₂ in the general formula (1) are p-hydroxybenzyl group and p-methoxybenzyl group. Polymer. 3. The alkali-soluble polyorganosilsesquioxane polymer according to claim 1, wherein R ₁ and R ₂ in the general formula (1) are p-hydroxybenzyl groups.