JPH0528829B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a resist containing a styrene polymer having silicon atoms as a component. Conventional Technology In recent years, in the manufacture of semiconductors, etc., as patterns have become finer, dry etching using gas plasma, etc. has been used instead of conventional wet etching in order to accurately transfer resist patterns onto substrates. It became. In general, styrene polymers have relatively good resistance to dry etching by gas plasma and the like, and are often used as resist materials. In recent years, multilayer resists using oxygen plasma have attracted attention, and a resist material having oxygen plasma resistance is desired as an upper layer thereof. Resist materials containing silicon atoms have excellent oxygen plasma resistance, and several of these resist materials are known. A typical example is siloxane-based polymers, but these polymers generally have a low thermal transition temperature and are viscous liquids or gums at room temperature, so they tend to attract dust and are difficult to adjust the film thickness. It has drawbacks such as difficulty. Recently, attempts have been made to use a copolymer of trimethylsilylstyrene and a crosslinking monomer as a resist material (Japanese Patent Application Laid-Open No. 15419/1983), but since this copolymer is produced by radical polymerization, the molecular weight The distribution becomes wide, and when this copolymer is used as a resist, the resolution is never sufficient. Problems to be Solved by the InventionObject of the Invention The present invention provides a resist that has a narrow molecular weight distribution and is made of a styrene-based polymer into which silicon atoms are introduced, and has excellent oxygen plasma resistance, dry etching resistance, and resolution. The purpose is to Means for solving the invention Summary of the invention The present invention is based on the general formula [In the formula, R ¹ , R ² and R ³ are the same or different C ₁ to _{C 6}
is an alkyl group or a C ₂ to C ₆ alkenyl group,
At least one of R ¹ , R ² and R ³ is an alkenyl group. The gist of the resist is a styrenic polymer consisting of repeating units of ] and having a weight average molecular weight of 3,000 to 3,000,000 and a weight average molecular weight/number average molecular weight of 1.0 to 1.2. Method for producing styrenic polymer The styrenic polymer used in the present invention has the general formula described above, and the polymer is produced by contacting a P-methylstyrene polymer with an organolithium compound to produce a lithiated P-methyl styrene polymer. Styrene polymer, then formula (R ³ ) (R ² ) (R ¹ )SiX [however, R ¹ , R ² and
R ³ has the same meaning as above, and X represents a halogen atom. ]
It can be produced by reacting with a silicon compound represented by: Each compound used in producing the polymer will be explained. P-methylstyrene polymer The P-methylstyrene polymer used in the present invention is P-methylstyrene (hereinafter referred to as PMS).
A polymer with repeating units of bone core, typically polyPMS. Poly PMS is PMS or PMS content of 95% or more,
Methylstyrene mixture, preferably 97% or more,
Solution polymerization carried out in an inert hydrocarbon solvent such as benzene or toluene, suspension polymerization carried out in a solution containing a suspending agent such as calcium phosphate, polyvinyl alcohol, or hydroxyethyl cellulose, or in an aqueous medium containing an appropriate surfactant. It can be obtained by polymerization using methods such as emulsion polymerization. Polymerization is
The polymerization may be carried out in the presence of a free radical type, anion type or cation type polymerization catalyst, or may be carried out by thermal polymerization. In the present invention, those having a weight average molecular weight of 3,000 to 3,000,000 can be used. A cross-linked version of these poly PMSs can also be used. Organolithium Compounds Organolithium compounds are represented by the general formula PLi. Specifically, compounds in which R is an alkyl group having 1 to 12 carbon atoms are mentioned, and typical compounds include methyllithium, ethyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, Examples include n-pentyllithium, tert-pentyllithium, hexylylithium, octyllithium, and todecyllithium, but butyllithium is particularly preferred. Silicon compound The silicon compound is represented by the above formula, and when R ¹ , R ² , and R ³ in the formula are alkyl groups, it is preferably a methyl, ethyl, n-propyl, or n-butyl group, particularly methyl, Ethyl group is preferred.
When R ¹ , R ² , and R ³ are alkenyl groups, vinyl, allyl, propenyl, isopropenyl, and butenyl groups are preferable, and vinyl and allyl groups are particularly preferable. X is preferably a chlorine atom. Reaction between PMS polymer and organolithium compound The reaction between PMS polymer and organolithium compound is as follows.
This can be carried out in a solvent that is inert to the organolithium compound. Examples of solvents that can be used include hydrocarbons such as hexane, heptane, octane, cyclohexane, benzene, toluene, and xylene, and ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, and dioxane. In the reaction, the PMS polymer is dissolved or swollen in these solvents, and then the organic lithium compound is allowed to act on the PMS polymer. At this time, components that increase the reactivity of the organolithium compound, such as amines, can be used. Amines that can be used include N,
N,N',N'-tetramethylethylenediamine is preferred. The reaction temperature can be freely set from -70°C to the boiling point temperature of each solvent, but in order to efficiently achieve a high lithiation rate, a temperature of room temperature or higher is desirable. Furthermore, the amount of the organolithium compound to be used can be arbitrarily set with respect to the existing paramethylstyrene bone core units, and the lithiation rate can be adjusted as desired. The amines may be used in an equivalent amount to the organolithium compound, but may be used in an excess amount. The reaction time is
Although it varies depending on the reaction temperature, it is usually 0.1 to 100 hours, and the lithiation rate can be increased by increasing the reaction time. The lithiated PMS polymer prepared in this way has high reactivity and reacts with moisture in the air, so it is desirable to use it in the subsequent reaction without separating it. Reaction between the lithiated PMS polymer and the silicon compound The reaction between the lithiated PMS polymer and the silicon compound can be carried out by directly adding the silicon compound to the first stage reaction system in which the lithiated PMS polymer is present and bringing them into contact. It will be achieved. The silicon compound is usually 1 to 100% of the organic lithium compound used in the previous step.
The amount used is twice the molar amount, preferably 1 to 10 times the molar amount. The reaction is carried out at -50°C to +150°C, preferably 0 to 50°C, at a temperature of 0.1
~100 hours, preferably 0.5 to 20 hours.
The produced polymer is preferably washed with water, dilute hydrochloric acid, etc., and is preferably purified by reprecipitation or the like. The styrenic polymer obtained as above consists of the above formula (), and this polymer ()
has a weight average molecular weight of 3,000 to 3,000,000, weight average molecular weight (w)/number average molecular weight (n) = 1.0 to
It has a very narrow molecular weight distribution of 1.2, and the content of silicon-containing substituents (-SiR ¹ R ² R ³ ) is usually 5 to 5.
It consists of 80 unit mol %, especially 5 to 50 unit mol %. R ¹ , R ² and R ³ in the above formula of the polymer () are the same as in the case of the silicon compound. That is, R ¹ to ^{R 3}
At least one of them is an alkenyl group. ^R1 ,
When R ² or R ³ is an alkyl group, a C ₁ -C ₄ alkyl group is preferable, and a methyl or ethyl group is particularly preferable. Further, in the case of an alkenyl group, a C ₂ -C ₄ alkenyl group is preferable, and vinyl and allyl groups are particularly preferable. When the styrene polymer thus obtained is used as a resist for manufacturing semiconductor devices, a commonly used spinner coating method can be used. The solvent and developer used to dissolve the polymer are not particularly limited, but include benzene, toluene,
Aromatic hydrocarbons such as xylene, halogenated aromatic hydrocarbons such as monochlorobenzene, dichlorobenzene, monochlorotoluene, etc. can be used. When the polymer is dissolved in the above-mentioned solvent and the solution is adjusted to a desired concentration, spinner coating is performed on a commonly used substrate, thereby forming a uniform resist layer on the substrate. The resist layer is usually
It is 0.2 to 1.0 μm. This resist layer is usually prebaked, and the conditions are generally 90-130℃.
It is 0.1 to 1 hour. Of course, the reaction may also be carried out under reduced pressure and at a lower temperature. Next, the pattern is baked by irradiation with electron beams, X-rays, deep ultraviolet rays, etc., post-baked if necessary, and then developed with the developer described above, to obtain a sharp negative pattern. Effects of the Invention The styrenic polymer according to the present invention has a very narrow molecular weight distribution, so it has excellent resolution, and since it contains silicon atoms, it can be used as a resist with excellent oxygen plasma resistance. It has the advantages of easy handling and excellent dry etching resistance. Furthermore, the pattern can be printed with a very small amount of radiation and has high sensitivity. Examples Hereinafter, the present invention will be explained in detail by examples.
The product was identified using the following equipment. ^1H NMR: The sample is a 20 wt% solution of _CDCl3 ,
Measured with Varian EM360A (60MHz). Measurement conditions: 20℃ ¹³ H NMR: The sample is a 20% by weight solution of CDCl ₃ ,
Varian XL-200 type, Fourier transform type
Measured with an NMR spectrometer. Measurement conditions: temperature 60°C, 60° pulse, pulse interval 30
seconds, totaling 900 times.Resist evaluation was conducted using the following equipment and conditions. Spinner: Manufactured by Takahashi Seiki Kogyo Co., Ltd., spinner model
TH-25 Electron beam lithography system: Elionix ELS-
3300. Irradiation conditions: Irradiation current 7.8×10 ^-11 A, beam diameter 0.1μ
m, accelerating voltage 20KV Film thickness measurement: Dektak manufactured by SLOAN Example 1 Synthesis of PMS polymer 98.3 mmol (11.6 g) of PMS, 0.16 mmol of sec-butyllithium and 280 ml of benzene were placed in a flask purged with nitrogen gas. The polymerization reaction was carried out at room temperature for 12 hours. When the obtained polymer was separated and analyzed, 11.6 g of a nearly monodisperse PMS polymer with w=79300 and w/n=1.06 was obtained. Synthesis of styrenic polymer The above obtained
Add 2.0g of PMS polymer and 40ml of cyclohexane,
It was stirred to form a solution. In this, n-butyllithium
Add an n-hexane solution containing 16.8 mmol and 17.3 mmol of tetramethylethylenediamine (TMEDA) and react at 50°C for 1 hour to lithiate.
A PMS polymer was obtained. Next, 54 mmol (7.3 g) of allyldimethylchlorosilane was added to this reaction system.
was added and reacted at 20°C for 3 hours. After washing the reaction solution with water, it was dropped into methanol to precipitate a polymer, yielding 2.5 g of a white polymer. When the molecular weight was measured, it was w = 81500,
It was found that the polymer was nearly monodisperse with w/n=1.08. As a result of ¹ H NMR analysis, the presence of allyldimethylsilyl groups was confirmed, and the integration ratio revealed that the introduction rate of allyldimethylsilyl groups was 39 unit mol%. Moreover, the 1H NMR chemical shift value of this polymer was as follows. ^1H NMR [δ (ppm)]: 7.02-6.10 (aromatic ring) 4.94,
4.72 ( -CH = CH2 ) _, 2.25
(

[Formula]) 2.08~1.05 (

【formula】

[Formula]), −0.05 (

[Formula]) Resist Evaluation The styrene polymer obtained above was dissolved in xylene to make a 10% by weight solution, and this solution was spin-coated onto a silicon wafer to a thickness of 0.5 μm. After prebaking at 90 to 130℃ for 30 minutes in air open, acceleration voltage 20KV, irradiation current 7.8×10 ^-11 A
When this resist-coated wafer was irradiated with an electron beam, the irradiation amount was 8.0× as shown in curve 1 in the drawing.
The residual film starts from 10 ^-7 C/cm ² and becomes 1.6×10 ^-6 C/cm ²
The film thickness became 50% of the initial thickness. Example 2 A lithiated PMS polymer was obtained in the same manner as in Example 1 using the monodisperse PMS polymer prepared in Example 1. Then diethylvinylchlorosilane 54
Millimoles (8.0 g) were reacted to obtain a diethylvinylsilylated PMS polymer. When measured in the same manner as in Example 1, w=80500 and the introduction rate of diethylvinylsilyl groups was 34 unit mol%. The 1H NMR chemical shift values were as follows. ^1H NMR [δ (ppm)]: 7.02-6.05 (aromatic ring), 5.95
〜5.64( -CH = CH2 ) _, 2.25
(

[Formula]), 2.08~1.05( ), 0.35 to −0.05(

[Formula]) Resist evaluation of the styrene polymer synthesized above was performed in the same manner as in Example 1, and as shown by curve 2 in the drawing, residual film began to form at an irradiation dose of 1.0×10 ^-6 C/cm ² . , 2.1×10 ^-6 C/cm ² and the film thickness became 50% of the initial thickness.

[Brief explanation of the drawing]

The drawing is a graph showing the electron beam irradiation sensitivity curve of the resist of the present invention. Curve 1 shows the resist of Example 1, and curve 2 shows the resist of Example 2.

Claims (1)

[Claims] 1. General formula [In the formula, R ¹ , R ² and R ³ are the same or different C ₁ to _{C 6}
is an alkyl group or a C ₂ to C ₆ alkenyl group,
At least one of R ¹ , R ² and R ³ is an alkenyl group. ] A resist containing as a component a styrenic polymer having a weight average molecular weight of 3,000 to 3,000,000 and a weight average molecular weight/number average molecular weight of 1.0 to 1.2.