JPS6310634A - Copolymer of sulfur dioxide with acetylene compound and vinyl compound - Google Patents

Abstract

PURPOSE:To obtain the title copolymer which can be decomposed highly sensitively with electron beams of X-rays and excels in dry etching resistance, by copolymerizing SO2 with an acetylene compound and a vinyl compound in the presence of a polymerization initiator. CONSTITUTION:SO2 is copolymerized with an acetylene compound (e.g., 1- methyne) and a vinyl compound (e.g., 1-butene) at -100-100 deg.C in the presence of a polymerization initiator (e.g., azobisisobutyronitrile) to obtain an at least ternary polymer comprising 30-50mol% structural units of formula I and 70-50mol% total of the acetylene compound and the vinyl compound, having a number-average MW>=500 and represented by formula II [wherein p is 1-10, q is 0-4, R<1-2> are each H, (CH2)nCH3, C6H5, SiMe3, CH2SiMe3 or CH2OH, n is 0-5, R<1-2> are bonded in a manner to form a cis or trans isomer, R<3-6> are each H, (CH2)nCH3 (wherein n is 0-4), R<7> is H, Cl or OCOCH3, OH, SiR<8>3, R<8> is CH3, C2H5 or C3H7 and j, k, l and m are the molar fractions of units of the copolymer].

Description

Detailed Description of the Invention [Field of Technology] The present invention relates to a ternary or more copolymer containing sulfur dioxide, an acetylene compound, and a vinyl compound as structural components, and a method for producing the copolymer. The present invention relates to a novel positive resist material that is decomposed with high sensitivity by electron beams or X-rays as an active ingredient and has dry etching resistance.

[Conventional technology]

The progress of LSI over the past few years has been remarkable.

High performance is also required of resist materials used for microfabrication of LSIs. That is, materials are required that are highly sensitive to light, electron beams, and X-rays and have high resolution. Furthermore, recently, dry etching has become mainstream in place of chemical etching at the microfabrication stage, and resist materials are also required to have dry etching resistance.

Conventional polymer materials for positive resists include copolymers of sulfur dioxide and olefins and methyl methacrylate polymers (Kiyotake Naraoka, "Precision Microfabrication of Electronics", Sogo Denshi Publishing) However, many positive resist materials cannot withstand plasma irradiation.

Conventionally well-known positive resists include poly(1-butenesulfone) (abbreviated as PBS), which has the characteristic of being decomposed with high sensitivity by electron beams.

However, its use is limited due to its poor dry etching resistance. Poly(1-hexyne sulfone) is also a positive resist that decomposes with high sensitivity when exposed to electron beams (
2.8X 1O-6C/cm'' (MIBK-
iPrOH1: Developed with 1)], has poor dry etching resistance like PBS. Furthermore, among poly(alkynesulfones), sulfone copolymers using acetylene compounds having fewer carbon atoms than 1-hexyne do not dissolve sufficiently well in general-purpose solvents.

[Purpose of the invention]

The technical problems of the present invention are: 1) improving and improving the solubility of poly(alkynesulfone) in solvents while maintaining the characteristic of decomposition with high sensitivity by electron beams; and 2) maintaining the solubility in solvents and , to improve and improve the dry etching resistance of poly(olefin sulfone) and poly(alkynesulfone).

The present inventor has conducted various studies in order to solve the above problems, and has discovered that a ternary or more copolymer having structural units of sulfur dioxide, an acetylene compound, and a vinyl compound, which will be described in detail later, is a new polymer compound that can be applied to the above-mentioned technology. The present invention was completed after discovering that the problem could be solved.

As is clear from the above description, the first object of the present invention is to provide a novel ternary or more copolymer having good solubility as structural units of sulfur dioxide, an acetylene compound, and a vinyl compound, and a method for producing the same. The second object is to provide a new use of the copolymer (positive resist material, and furthermore, a positive resist material having dry etching resistance).

[Invention composition effect]

The present invention (three inventions) includes the following (1), (4) and (
It has each main structure of 5) and the embodiment structure of (2) to (3).

(1) A linear polymeric compound consisting of 30 to 50 mol% of an acetylene compound and a vinyl compound and having a number average molecular weight of 500 or more, whose structural units are sulfur dioxide, an acetylene compound, and a vinyl compound. Copolymer of 3 or more elements.

(2) The copolymer according to item (1) above, which contains 2 mol % or more of an acetylene compound or a vinyl compound as a structural unit based on the copolymer.

(3) Below formula CI) ...(I) The copolymer according to item (1) above, which is represented by:

[Here, p-t-10, q-o~4, and the substituent R
R1 and R2 are H, CCH2)n, respectively.
CH3 (n=0 to 5), C6H5, SiMe:
+, (H2SiMez or CH20H, (R
The bonding mode of 1 and R2 groups may be either cis or trans form), and R3-R6 are H, (CH2)nc
Hs (here nsO~4) and R7 is H, C:1
,0CO(+(3,0)lJ+R3(R' bonding position is o-.

s- or p-), and R8 is Cl31
02H5, C3H7, roughly j, ni, I, and integer correspond to the mole fraction of the copolymer, and each structural unit is irregularly distributed in the copolymer (copolymer) main chain It does not mean a so-called block copolymer,
] (4) A mixture of sulfur dioxide, an acetylene compound and a vinyl compound is heated to -100 to 100 in the presence of a polymerization initiator.
A method for producing a ternary or more copolymer comprising sulfur dioxide, an acetylene compound, and a vinyl compound, the method comprising copolymerizing at a temperature of °C.

(1) A copolymer of 3 or more elements consisting of sulfur dioxide, an acetylene compound and a vinyl compound, which is a linear polymer compound with a number average molecular weight of 500 or more and consisting of 30 to 50 mol% of an acetylene compound and a vinyl compound. Positive resist material as an active ingredient.

The structure and effects of the present invention will be explained in detail below.

As is clear from the purpose of the invention, the copolymer of the present invention is
Preferably, it is represented by formula (I) and is soluble in a solvent, and is desired to have excellent sensitivity and resolution to electron beams or X-rays, and excellent dry etching resistance.

If we relate the above formula (I) to these, in terms of solubility, the order is [b>[]+ (same below if descriptions in parentheses are omitted), and in terms of sensitivity, [lb>[b, [] crow.

[]+ contributes in this order, and []+, [b, and [Im], which have a compound containing an aromatic ring or a silyl group as a structural unit, are excellent in terms of dry etching resistance.

As described above, each of the structural units of formula (I) has its own advantages and disadvantages, and each structural unit is indispensable in order to obtain well-balanced performance. Then, a copolymer can be obtained by appropriately selecting raw materials and blending ratio 1 polymerization conditions depending on the required performance. For these reasons, the molar fractions of j and +l+m are limited. Also, in the above formula CI), []j, [1, '[1m
The composition ratio in, for example, the SO2: RIC=CR2 ratio is a ratio of 1=1, whereas the composition ratio in j]+ can change depending on the value of p. However, the mole fraction of the structural unit Hso2+ cannot exceed 50 mol%.

The acetylene compound used in the present invention is not limited, but includes, for example, acetylene, 1-methine, 1-butyne, 1-pentyne, 1-hexyne, 1-heptyne, 1-octyne,
Phenylacetylene, 1-trimethylsilylpropyne,
Examples include 3-trimethylsilylpropyne and 1-trimethylsilylpropargyl alcohol.

Vinyl compounds used in the present invention are not limited, but examples include 1-butene, 2-methyl-1-pentene, 2-pentene (including cis and trans forms), l-hexene, 1-
Examples include heptene, styrene, chlorostyrene, acetoxystyrene, hydroxystyrene, trimethylsilylstyrene), trimethylvinylsilane, trimethylallylsilane, and the like.

The ternary and multicomponent copolymers of the present invention (hereinafter sometimes referred to as the copolymers of the present invention) contain sulfur dioxide, one or more of the above acetylene compounds, and one or more of the above vinyl compounds. It can be synthesized as a raw material. The composition of the copolymer of the present invention can be controlled by selecting sulfur dioxide, the acetylene compound and the vinyl compound, the blending ratio, and the polymerization temperature, and the molecular weight can be controlled by appropriately selecting the type, amount, and polymerization temperature of the polymerization initiator. .

As the polymerization initiator, any initiator for free radical polymerization can be used. As a preferable example,
Mention may be made of azobisisobutyronitrile, 1-butyl hydroperoxide or di-tert-butyl peroxide. The copolymer of the present invention can also be obtained by light irradiation.

In any of the above cases, the amount of polymerization initiator used can be increased or decreased depending on the desired molecular weight of the copolymer. The range of the practical usage amount is not limited, but 1 to 100
mmol/fL.

The polymerization temperature ranges from -100 to 1,000 depending on the set molecular weight of the desired copolymer and the desired composition ratio shown in the above formula (I).
A predetermined temperature can be selected within a range of 100°.

In formula (I), [ ]j. [To. The composition ratio in [] does not depend on the polymerization temperature, giving a ratio of -1:l, whereas the composition ratio in []+, that is, as the polymerization temperature is lowered, the ratio becomes 1:1. approach.

On the other hand, when the copolymer of the present invention is used as an electron beam or X-ray resist, the decomposition sensitivity by electron beam or X-ray irradiation improves as the value of p approaches 1.

The copolymerization reaction involved in the method of the present invention can be carried out by a bulk polymerization method or a solution polymerization method. Although the solvent used in the solution polymerization method is not limited, for example, chlorobenzene,
-Dichlorobenzene or dichloromethane are preferred.

The time required for the copolymerization reaction varies depending on the copolymerization conditions, but
~120 hours, preferably 4 to 48 hours. After the predetermined copolymerization time has passed, unreacted monomers, solvent, etc. are separated,
A copolymer is obtained in solid or (if necessary) solution form.

By selecting the type and amount of the polymerization initiator, the polymerization temperature, and the polymerization solvent as described above, a copolymer having a number average molecular weight of 500 or more and a predetermined structural unit ratio can be obtained.

When the copolymer of the present invention is used as a resist material, its number average molecular weight affects the resist performance of the material, and in terms of performance, the range of the molecular weight is 50% in terms of number average molecular weight.
0 or more, particularly preferably to,ooo to 5G0.000.

Can the multi-component copolymer of the present invention be uniformly applied to a substrate by spraying or spin-coating as a solution in a general-purpose organic solvent? Hj
can. The solution is usually used at a concentration of the copolymer of about 3 to 20% by weight, preferably about 4 to 10% by weight. Preferred solvents include those having a boiling point below the thermal decomposition initiation temperature of the copolymer, such as dioxane, chlorobenzene, and methyl cellosolve acetate.
) (MCA) etc. are preferred.

In an embodiment of the method of using the copolymer of the present invention as a positive resist material, a solvent solution of the above-mentioned copolymer, that is, a resist solution, is spin-coated onto a base material, and then the solvent in the coated material is heated and evaporated. to form a uniform resist film. The thickness of the film is 0.4
The thus obtained film, which is preferably 1 #Lm, is irradiated with a controlled electron beam or X-ray,
Causes decomposition in the irradiated area. Next, development is performed by dissolving the irradiated area using a developer (described later). Examples of suitable developers include methyl ethyl ketone, ethyl acetate, methyl cellosolve acetate,
A good solvent such as chlorobenzene, cyclopentanone, dioxane or tetrahydrofuran and a poor solvent such as 2-methoxyethanol, isopropyl alcohol or ethanol are mixed in an appropriate ratio, for example, 10 parts of good solvent: 1 part of poor solvent or 1 part of good solvent: poor solvent. Examples include mixed solvents mixed at a potting ratio of 10 (in both cases).

The copolymer of the present invention containing an acetylene compound and a vinyl compound having a silyl group or an aromatic ring as a side chain group plays a role as a retaining MW2 during substrate processing when used as a resist material. That is, in a resist film having silyl groups or aromatic rings, the main chain of the polymer is decomposed by plasma etching, and at the same time, the aromatic rings are cross-linked to form a barrier layer. Further, in a compound containing a silyl group, the silyl group is oxidized by oxygen plasma, and a SiOx layer is formed on the surface of the resist layer, which becomes a barrier layer and exhibits superior plasma resistance.

As shown in the test example, the copolymer of Terminal 11 containing a compound having an aromatic ring and a compound having a silyl group, such as trimethylsilylstyrene, trimethylvinylsilane, 3-trimethylsilylpropyne, etc., as a structural unit has plasma resistance. By containing 10 to 30 mol% of these structural units in the copolymer, the purpose of imparting dry etching resistance can be fully achieved.

The present invention will be explained below with reference to Examples.

Example 1 65 ml of 0-dichlorobenzene and 160 g of 7zobisisobutyronitrile were placed in a 200 tJL pressure-resistant glass polymerization tube.
Put in. Next, the contents in the polymerization tube were repeatedly subjected to vacuum aeration under freezing to remove oxygen, and the contents were weighed in advance.
-Add 1G, 8g of butyne and 11.2g of 1-butene to the polymerization tube.Next, add 8.8ml of liquid sulfur dioxide, which has been dehydrated and dried with P2O5, to the polymerization tube at -1θ℃, and mix well. . This polymerization tube was placed in a constant temperature water bath at 50° C. and polymerized for 16 hours with stirring. Then a, the polymerization tube is rapidly cooled to below -50°C to stop the polymerization reaction, and after opening,
Unreacted 502 gas is expelled.

Add a small amount of methyl ethyl ketone (MEK) to the remaining polymerization solution.
When the homogeneous solution is added to a large amount of methanol under stirring, a white copolymer precipitates. This copolymer is collected through a glass filter, the resulting copolymer is dissolved in a small amount of tetrahydrofuran (T) IF), purified by pouring it into methanol again, and vacuum-dried at 30° C. for 24 hours.

Yield is 8.8g. The IR spectrum of this copolymer is shown in FIG.

According to the IR spectrum, NMR analysis, and elemental analysis, the wood copolymer is a ternary copolymer of 1-butyne-1-butene-9O2, and its composition is 27 mol% of l-butyne units,
-Butene units were 23 mol%, and 502 units were 50 mol%. Therefore, when the ternary copolymer obtained here was analyzed by GPC (gel fist permeation chromatography), the number average molecular weight was 89,000 in terms of polystyrene, and the degree of dispersion was 4.0. there were. Also,
As shown in Table 1, this terpolymer was well dissolved in general purpose solvents.

Example 2 A similar copolymerization reaction was carried out using 18.4 g of 1-hexyne instead of 8 g of 1-butyne IG in Example 1. Yield is 1
It is 0.2g. Figure 2 shows the IR spectrum of this copolymer.
Shown below.

According to IR and NMR spectra and elemental analysis values, the wood copolymer is a terpolymer consisting of 1-hexyne-1-butene-5O2, and its composition is 32 mol% of 1-hexyne units;
The l-butene units were 18 mol%, and the S02 units were 50 mol%. Therefore, also has the structure of formula (3). GPC analysis of this ternary copolymer revealed that the number average molecular weight was 145,000 in terms of polystyrene, and the degree of dispersion was 2.4. Furthermore, as shown in Table 1, this copolymer was well dissolved in general purpose solvents.

Comparative Examples 1 and 2 1-Butyne, S02 and 1-
Using hexine and SO2 as raw materials, O-dichlorobenzene as a copolymerization solvent, azobisisobutyronitrile as a polymerization initiator, copolymerization reactions were carried out at 50°C, and l-butyne-9O2 and 1- hexyne-5O2-2
The original copolymer was obtained (details are described in Japanese Patent Application No. 81-078505).

Table 1 shows the solubility of this binary copolymer.

(Table 1) Name of copolymer-soluble solvent Example 1 Example 2 Comparative example 1 Comparative example 2 MCA OOX Δ MEK OOX X Acetone o o x
xTHF OOX O Dioxane 0 0 × Δ This binary copolymer is a 1:l, IIJjt alternating copolymer.

Test Example 1 The terpolymer obtained in Example 1 was dissolved in methyl cellosolve acetate (MCA) to obtain a 5.0 wt % solution, which was filtered through a 0.2 pL intestinal filter. This solution was applied onto a silicon wafer using a spinner and the number of revolutions was 15.
The coating was applied for 60 seconds at 0 rpm, and the object to be coated was prebaked at 120° C. for 1 hour in a clean oven. The coating film thickness after prebaking was 0.45p.

This substrate was subjected to electron beam irradiation using an electron beam lithography device and varying the irradiation dose.
After development was performed by immersion method at room temperature for 1 minute in a mixed solvent system with H), rinsing was performed for 30 seconds with 1PrOH. After this, post-baking was performed in an oven at 120°C for 30 minutes. The remaining film of each pattern thus obtained was measured by the stylus method, and the irradiation dose (sensitivity) of the part where the remaining film was completely removed was determined to be 3 x 1O-5C/c.
rr (There was.

Test Example 2 The sensitivity of the terpolymer obtained in Example 2 was measured in the same manner as in Test Example 1. The results are shown in Table 2.

Example 3 82 layers of azobisisobutyronitrile, 12.3 g of 1-hexyne, p-
8.8 g of trimethylsilylstyrene was added, and then the oxygen in the polymerization system was removed by turning back the exhaust while cooling, and 22-4 g of 1-butene, which had been weighed in advance, was added to the polymerization tube while cooling.

Next, 17.5 volumes of liquid sulfur dioxide, which had been dehydrated and dried at 2205, was added to the polymerization tube at -1O<0>C, the tube was sealed, and the mixture was thoroughly mixed. This polymerization tube was placed in a constant temperature water bath at 50°C and reacted for 24 hours.

Then, the polymerization tube is rapidly cooled to below -50° C. to stop the reaction, and after opening, unreacted 502 gas is expelled.

A small amount of tetrahydrofuran was added to the remaining reaction solution to make a homogeneous solution, and the homogeneous solution was poured into a large amount of methanol with stirring to precipitate white polybu. Thereafter, purification and dry storage were performed in the same manner as in Example 1 to obtain 3.4 g of a copolymer. The IR spectrum of this copolymer is shown in FIG.

According to the analysis of IR and NMR spectra and the elemental analysis values, Sailor Polymer is a quaternary copolymer of 1-hexyne-1-butyne-p-trimethylsilylstyrene-9O2, and its composition is 9 mol% of 1-hexyne units. 1-butene unit: 32 mol%, p-trimethylsilylstyrene unit: 12 mol%
, the sulfone unit was 47 mol%. Therefore, the quaternary copolymer obtained here can be expressed as shown in formula (4).

GPC analysis of this quaternary copolymer revealed that the number average molecular weight was 84,000 in terms of polystyrene, and the degree of dispersion was 2.
It was 8.

In addition, the quaternary copolymer obtained in this experimental example was prepared using general-purpose solvents such as tetrahydrofuran, dioxane, chloroform,
It was sufficiently dissolved in methyl cellosolve acetate, etc.

Test Example 3 The sensitivity of the quaternary copolymer obtained in Example 3 was measured in the same manner as in Test Example 1. The results are shown in Table 2, and the resist-coated substrate was etched using a parallel plate etching device using CCIa gas and RF power density of 0.841/cr.
Etching was performed for 10 minutes under the conditions of n', pressure of 10 Pa, and gas flow rate of 150 cc/win, and the etching rate was determined to be 350 A/win.

Table 2 Copolymer sensitivity measurement test example No. l 2
3 Dissolving solvent and MCA MCA
MCA solution concentration 5.0wt% 5,
Out% 5, Out% conditions (30 minutes)
(30 minutes) (30 minutes) Sensitivity (C/cm'')
3X10-5 1XIO-58X10-6

[Brief explanation of the drawing]

Figures 1.2 and 3 are infrared absorption spectra of the terpolymer according to the present invention, respectively. that's all

Claims (1)

[Scope of Claims] (1) 30 to 50 mol% of the structural unit represented by ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and a total amount of 50 to 70 mol%
A ternary or more copolymer having structural units of sulfur dioxide, an acetylene compound, and a vinyl compound, which is a linear polymer compound having a number average molecular weight of 500 or more. (2) The copolymer according to claim (1), which contains 2 mol% or more of an acetylene compound or a vinyl compound as a structural unit based on the copolymer. (3) The copolymer according to claim (1), which is represented by the following formula (I) ▲ Numerical formula, chemical formula, table, etc. ▼ ... (I). [Here, p = 1 to 10, q = 0 to 4, and the substituent R
For R^1, R^2 are H, (CH_2
)_nCH_3 (here n=0 to 5), C_6H_5,
SiMe_3, CH_2SiMe_3 or CH_2
OH (the bonding mode of R^1 and R^2 may be either cis or trans), and R^3 to R^6 are H
, (CH_2)_nCH_3 (here n=0 to 4), and R^7 is H, Cl, OCOCH_3, OH, SiR
^8_3 (The bonding position of R^1 may be o-, m-, or p-), and R^8 is CH_3, C_2H_
5, C_3H_7, and further, j, k, l, m correspond to the mole fraction of the copolymer, and each structural unit is randomly distributed in the copolymer (copolymer), and the main chain is It consists of ] (4) A mixture of sulfur dioxide, an acetylene compound, and a vinyl compound is heated to -100 to -100 in the presence of a polymerization initiator.
A method for producing a ternary or more copolymer comprising sulfur dioxide, an acetylene compound, and a vinyl compound, the method comprising copolymerizing at a temperature of 100°C. (5) 30-50 mol% ▲ There are mathematical formulas, chemical formulas, tables, etc. The structural units indicated by ▼ and the total amount are 50-70 mol%
A positive resist material containing as an active ingredient a ternary or more copolymer consisting of sulfur dioxide, which is a linear polymer compound with a number average molecular weight of 500 or more, and an acetylene compound and a vinyl compound. .