JPS62245245A - Resist containing styrene copolymer as component - Google Patents

Abstract

PURPOSE:To obtain the resist having a narrow mol.wt. distribution and excellent oxygen plasma resisting and dry-etching resisting properties and resolution by incorporating the styrene copolymer having repeating units of compds. shown by specific formulas to the titled resist. CONSTITUTION:The titled resist comprises the styrene copolymer contg. the repeating unit shown by formulas I-III. In formulas I-III, R<1>-R<3> each are same or different with each other and 1-6C alkyl or 2-6C alkenyl group, one of R<1>-R<3> groups is alkenyl group. The styrene copolymer is composed of either a random copolymer contg. the repeating units shown by formulas I-III or a block copolymer in which the random copolymer contg. the repeating units shown by formulas I and II is block-polymerized with a polymer contg. the repeating unit shown by formula III. Preferably, the styrene copolymer is composed of the random copolymer contg. the repeating units shown by formulas I-III. The compound ratio of the repeating units I-III is 1-70mol% unit of formula I, 1-97mol% unit of formula II and 2-98mol% unit of formula III.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a resist containing a styrenic copolymer having silicon atoms as a component.

Background of the Invention In recent years, in the manufacture of semiconductors, etc., as patterns have become finer, dry etching using gas plasma has been used instead of conventional wet etching in order to accurately transfer resist patterns onto substrates. 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 of such polymers is siloxane-based polymers, but this poly-i generally has a low thermal transition temperature and is a viscous liquid or gum-like at room temperature, so it easily attracts dust and has a low film thickness. It has drawbacks such as difficulty in adjustment.

Recently, attempts have been made to use a copolymer of trimethylsilylstyrene and a crosslinking monomer as a resist material (Japanese Patent Laid-Open No. 59-154
However, since this copolymer is produced by radical polymerization, the molecular weight distribution becomes wide, and when this copolymer is used to make a resist, the resolution is never sufficient. I can not say.

Problems to be Solved by the InventionPurpose of the Invention The present invention provides a styrene-based copolymer having a narrow molecular weight distribution and into which silicon atoms are introduced, which has oxygen plasma resistance,
The purpose of the present invention is to provide a resist with excellent dry etching resistance and resolution.

Means for Solving the Invention Summary of the Invention The present invention relates to a resist composition containing a styrene copolymer consisting of a bond of repeating units of @ and (Q) as a component. R1, RR and R3 have the same or different carbon numbers 1-
It is 6 alkyl groups or an alkenyl group having 2 to 6 carbon atoms, and at least one of R1, Hs and R1 is an alkenyl group. Also) is 1 to 70 mol, Φ) is 1 to 9
7 mole attack. (q is 2A-98 molti).

Styrenic copolymer The styrenic copolymer that is a component of the resist of the present invention is
The repeating units of (4), @ and (C) above are randomly combined, or (b) the random bonding part of the repeating unit and (b) the repeating unit and (C) the repeating unit part. is a four-piece combination. Preferably a prisoner, (g)
, (C) is a random copolymer. ), @ and (C
) are (A) 1-70 mol, g3) 1-97 mol, and (C) 2-98%, but especially (A) 5-98 mol.
50 mol% (C) 20 to 80 mol% is preferred when used as a resist.

This styrenic copolymer has a weight average molecular weight of several thousand to several million, and has a weight average molecular weight Mn=1. (1-1,
No. 5 is preferable because it has a great effect when used as a resist.

Production method of styrenic copolymer Styrenic copolymer is p-methylstyrene (hereinafter referred to as PM
It's called 8. ) and α-methylstyrene (hereinafter referred to as αM8).
It is called MS copolymer. ) is brought into contact with an organolithium compound to partially lithiate the para-methyl groups in the PMB copolymer, and then the formula (R1) (Rffi ) (R1
) 81X (However, R1゜R3 and R3 are the same or different alkyl groups having 1 to 6 carbon atoms or alkenyl groups having 2 to 6 carbon atoms. be. Moreover, X represents a halogen atom. ] It can be produced by reacting with a silicon compound represented by:

Each compound used in producing the styrenic copolymer will be explained.

■ PMS copolymer PMS copolymer can be produced by random or block copolymerization of PM8 and αM8t-1 by ordinary radical polymerization method or living polymerization method. However, especially when living polymerization method is adopted, narrow This is desirable because a copolymer with a well-defined molecular weight distribution can be obtained. Further, if the repeating units () of the styrene copolymer are uniformly dispersed, it will be more effective when used as a resist, so a random copolymerization method is preferable.

Living polymerization is carried out in the presence of an initiator which forms a styryl anion, such as an organolithium compound such as n-butyllithium, formula -butyllithium. Moreover, living polymerization can be performed in the presence of a solvent. As a solvent, hexane, which is inert to the initiator and generated anions,
Examples include hydrocarbons such as heptane, octane, cyclohexane, benzene, toluene, and xylene, and ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, and dioxa7.

Living polymerization is performed using PMS and αMat--80℃~+50℃
It is carried out by reacting at a temperature of °C for α5 to 50 hours. Random copolymerization is carried out by copolymerizing PMS and αM8t simultaneously, and block copolymerization is carried out by copolymerizing PMS and αM8t simultaneously.
This is carried out by first homopolymerizing one of MS or αMS and then copolymerizing the other.

The usage ratio of PMS and αM8 is usually PM8/αMS (molar ratio) 2 = 98 / 9 B ~ 2, preferably 2
5-75/75-25. Thus, the number average molecular weight of thousands to millions, preferably 10,000 to 500,000, W/n less than 2.0, preferably 1.0 to 1.5, PM8 moiety/αMS A PMS copolymer having the above mole ratio of parts is obtained.

(2) Organolithium Compound The organolithium compound used in lithiation of the PMEI copolymer is represented by the general formula RLi. 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, -butyllithium, tert-butyllithium. , n-pentyllithium,
Examples include tart-pentyllithium, hexylylithium, octyllithium, dodecyllithium, etc., but butyllithium is particularly preferred.

(2) Silicon compound The silicon compound is represented by the above formula, and in the formula, R1, 1 (if R1 is an alkyl group, it is preferably a methyl, ethyl, n-propyl, n-butyl group,
Particularly desirable are methyl and ethyl groups. Also Hl, RM
, When R1 is an alkenyl group, it is preferably a vinyl, allyl, propenyl, impropenyl or butenyl group, particularly a vinyl or allyl group. X is preferably a chlorine atom.

Reaction between FMS copolymer and organolithium compound The reaction between the PMS copolymer and organolithium compound can be carried out in a solvent that is inert to the organolithium compound. Solvents that can be used include hexane, heptane, octane,
Examples include O hydrocarbons such as cyclohexane, benzene, toluene, and xylene, and ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, and dioxane. In the reaction, the PMS copolymer is dissolved or swollen in these solvents, and the organic lithium compound is allowed to act on the PMS copolymer. At this time, components that increase the reactivity of the organolithium compound, such as amines, can be used. As the amine that can be used, N, N, N', N'-tetramethylethylenediamine is desirable.

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. Further, the use of the organolithium compound 11 can be arbitrarily set with respect to the existing paramethylstyrene bone core unit, and the lithiation rate can be arbitrarily adjusted. The amines may be used in an equivalent amount to the organolithium compound, but may be used in an excess amount. The reaction time varies depending on the reaction temperature, but is usually tt1 to 100.
The lithiation rate can be increased by increasing the reaction time.

The lithiated PMS Kyodo merger that was regulated in this way was
It is highly reactive and reacts with moisture in the air, so it is desirable to use it in subsequent reactions without separating it.

Reaction between the lithiated PMB copolymer and a silicon compound The reaction between the lithiated PMS copolymer and a silicon compound is carried out by directly adding a silicon compound to the first reaction system in which the lithiated PMB copolymer is present. This is achieved by

The silicon compound is usually used in a molar range of 1 to 100 times, preferably 1 to 10 times, the mole of the organolithium compound used in the first stage. The reaction is carried out at -50°C to +150°C, preferably 0 to 50°C, for α1 to 100 hours, preferably [15 to
It will be held for 20 hours. The produced polymer is preferably washed with water, diluted hydrochloric acid, etc., and is preferably purified by reprecipitation or the like.

R1, Ha, and Ra of the repeating unit Q of the styrene copolymer obtained as described above are the same as in the case of the silicon compound. That is, at least one of R1-R1 is an alkenyl group. When R1, R1 or R3 is an alkyl group, a C1-C4 alkyl group is preferable, and a methyl or ethyl group is particularly preferable.

Further, in the case of an alkenyl group, a C3-C4 alkenyl group is preferable, and a vinyl or allyl group is particularly preferable.

When the styrene copolymer thus obtained is used as a resist in the production of semiconductor devices, a commonly used spinner coating method can be used.

The solvent and developer used to dissolve the copolymer are not particularly limited, but include aromatic hydrocarbons such as benzene, toluene, and xylene, and halogenated aromatic hydrocarbons such as monochlorobenzene, dichlorobenzene, and monochlorotoluene. etc. can be used.

When the copolymer is dissolved in the above-mentioned solvent and a solution of a desired concentration is used to perform spinner coating on a commonly used substrate, a uniform resist layer is formed on the substrate. The resist layer is usually (L2~to#ttt). This resist layer is usually prebaked, and the conditions are generally 90~150°C for 11~1 hour. Of course, it can be performed at a lower temperature under reduced pressure. Good too.

Next, the pattern is baked by irradiation with electron beams, X-rays, far ultraviolet rays, etc., and after post-baking if necessary, it is developed with the developer described above to obtain a sharp negative pattern. can.

Effects of the Invention The styrenic copolymer according to the present invention has a very narrow molecular weight distribution, so it has an excellent degree of decomposition, and since it contains silicon atoms, it has excellent oxygen plasma resistance and can be used as a resist. It has the advantages of polymers such as ease of handling and excellent dry etching resistance. Furthermore, it is possible to print a pattern (with a very small amount of radiation) and has high sensitivity. Also, since the copolymer has excellent heat resistance, it does not swell during development, and therefore has excellent dissolving power.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples.◇Identification of products was performed using the following equipment.

'HNMR: The sample was a 20% by weight solution of CDC1,
Varian ml EM56 GA! (60M
Measured in Hg).

゛゛　Measurement conditions; 20℃ Further, resist evaluation was performed using the following equipment and conditions.

Spinner: Behind Mikasa Co., Ltd., Spinner I! (-0
2-disc electron beam lithography device: Elionix MUS-50QQ
Irradiation conditions: Irradiation current fL2. a~&OX10-11A, beam diameter 101 μm, acceleration voltage 20 kV Film thickness measurement 2 Rank Taylor Hopson, Tough Step Example 1 Synthesis of PMB copolymer In a flask purged with nitrogen gas, tetrahydrofuran 110011I purified by distillation and n -butyllithium 1
54 mmol was added, cooled in a dry ice-methanol bath, and stirred to obtain a solution. In a separate container, pMsa s- and 6M815- were placed under a nitrogen gas atmosphere and mixed. This mixture a was added to the previous n-butyllithium solution, and the polymerization reaction was started while stirring. After 2 hours, methanol 2- was added to stop the polymerization reaction.

Next, the reaction solution was poured into methanol to precipitate 1115t of PMS copolymer. When the obtained PMS copolymer was dissolved in tetrahydrofuran and measured by GPC, Mw=5 C4400, My/Mn=1.
It was 58. Further, as a result of H''NMR analysis, FM85 min was 50% mol% (1M 89 min was 50 mol%).

Furthermore, the glass transition temperature (Tf) of this PMS copolymer
was 152.2°C.

Synthesis of styrenic copolymer Into a flask purged with nitrogen gas was added the PMS copolymer 2. Of and 40-cyclohexane were added and stirred to form a solution. A solution of 17.4 mmol of n-butyllithium in n-hexane and 17.4 mmol of N,N,N',N'-tetramethylethylenediamine (TMIICDA) were added to this, and the mixture was reacted at 50°C for 2 hours to lithiate. PM
B copolymer.

The reaction system was then cooled to t-20°C, 40 mmol (!L4f) of allyldimethylchlorosilane was added, and the reaction was continued for 2 hours. After washing the reaction solution with water, it was dropped into methanol to precipitate a polymer, yielding a white polymer 2.25F. When measured by GPC, Mw=44,70
0, My/Mn = 142. Also, Tf is 9a5
It was ℃.

The I HNMR chemical shift values of this polymer were as shown below.

IHNMR (δ(ppm)): 7.12~&
14 (benzene ring), 5.74 (-C tan = C horse), 4
．． 87,4.82(-CH.

;Cdangu), 2.24 (-@)-Cdans),
2.08 to 1.14 (-CH2-81-CH* -,
main chain), 148~(LOO
The styrenic copolymer was found to be a random copolymer consisting of the following repeating units (6) and (C).

) (C) HsC-81-CH.

CH, -CH=CH.

Resist Evaluation A 10% xylene solution of the styrene copolymer obtained above was applied to the back of the resist. Spread this solution onto a silicon wafer.
It was spin-coded to a thickness of 54°C and prebaked at 70°C for 30 minutes. Next, it was irradiated with an electron beam under the above conditions, developed with a mixture of cyclohexanone and Impropatool, and heated at 120°C.
After post-baking for 20 minutes, a relationship (sensitivity curve) between the irradiation amount and the normalized residual film rate as shown in the drawing was obtained.

When a fine pattern of 13 μm was resolved for the pattern after the post-baking, it was found that the resulting pattern had good rectangularity and little swelling during development. In addition, when this resist pattern was heated in an open state, the temperature was 120℃, 2
No deformation occurred even after 0 minutes.

In the same manner as in Example 1, FMS & 4- and αMS 2
．． 8- was copolymerized to obtain PMB copolymer 1α9t.

My of this PMB copolymer is 57.600, My/Mn
was 1.41, and Tf was 1216°C. Also, P
The M8 portion was 7aO mol, and the αM8 portion was 25.0 mol. This copolymer 2. Of was lithiated in the same manner as in Example 1 and then reacted with allyldimethylchlorosilane to obtain 2.2 ft of white polymer. This styrenic copolymer has h of 47,500 and MY/Mn of 1.
57,'rf was 940°C. Also, it consists of the same repeating units (A), CB), and (C) as in Example 1,
(A)sy, e 03)! ? , 1 (C)ts, o was a random copolymer.

When this styrene copolymer was subjected to resist evaluation in the same manner as in Example 1, a sensitivity curve as shown by the broken line in the drawing was obtained. A fine pattern of 15 μm was resolved, but the rectangularity,
Heat resistance was good as in Example 1.

Example 3 In the same manner as in Example 1, FMS λ8- and αMe a5-
was copolymerized to obtain PMS copolymer 1α4f.

This PMS copolymer had a W of 25,800, a W/Mn of 1.25, and a Tf of 1567°C. Also, PM
The 8 part was 250 molti and the αM8 part was 750 molti. This combination 2. Of was mixed with allyldimethylchlorosilane, which had been lithiated in the same manner as in Example 1, to obtain a white polymer 2.42. W of this styrene thread joint is 30.800, Mw/Mn Ut34, T
ft! The temperature was 154.4°C. In addition, the same repeating units as in Example 1 IA), CB), (C), (8
A random copolymer of xa, i 03) *, s (C) ts, o.

The resist was evaluated in the same manner as in Example 1, and a sensitivity of -1 Mt as indicated by the dotted line in the drawing was obtained. (When a fine pattern of 134 m was resolved, it had good rectangularity and heat resistance, and 140 m of fine pattern was resolved.
It did not deform even when heated to ℃.

[Brief explanation of drawings]

The drawing is a graph showing the electronic powder irradiation sensitivity curve of the resist of the present invention. Among the corrective agents: 1) Akira agent: Hagiwara - ・Kyo agent: Atsuo Anzai

Claims (1)

[Scope of Claims] A resist containing as a component a styrene copolymer consisting of the following repeating units (A), (B) and (C). (A) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [However, R^1, R^2 and R^3
are the same or different alkyl groups having 1 to 6 carbon atoms or alkenyl groups having 2 to 6 carbon atoms, and R^1, R^2 and R
At least one of ^3 is an alkenyl group. Also (A)
is 1 to 70 mol%, and (B) is 1 to 97 mol%. (C) is 2 to 98 mol%. ]