JPH05333553A - Silicone resin and composition using that - Google Patents

Abstract

PURPOSE:To obtain a silicone resin having coating property and excellent hardening characteristics and thermal stability after hardened by constituting the resin of copolymers of at least two specified monomer units. CONSTITUTION:This silicone resin consists of copolymers of at least two monomers selected from a monomer unit expressed by formula I, monomer unit expressed by formula II, and monomer unit expressed by formula III. In formulae I-III, R represents verious tertiary alkyl groups such as -C(CH3)3, -C(C2H5)3, and-(CH3)2, or 1-alkylphenyl groups or 1,1-dialkylphenethyl groups such as alpha-phenethyl group. The silanol content (by mol% expressed by OR/(OR+ OH) in the copolymer) is 10-90mol%. By this method, the obtd. silicone resin consists of such copolymers having a structural part in which a silanol is partially protected in the form of Si-O-R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone resin and a composition using the same, which can be used as a resist, an etching mask, an insulating film, a molding material and the like used in the manufacture of semiconductor devices and the like. ..

[0002]

Silicone resins are well known and used in various industrial fields. For example, in the semiconductor field, as a constituent material of an insulating film or a passivation film of a solid-state element,
The use of silicone resin instead of the inorganic SiO ₂ film has been studied. This is because the silicone resin has advantages such as excellent step coverage as compared with the SiO ₂ film formed by the CVD method or the like. Further, silicone resin is also used as a constituent material of a resist for microfabrication and a constituent material of an etching mask during oxygen plasma etching.

As a conventional silicone resin which can be used as an insulating film, a passivation film, etc., for example, a photosensitive heat-resistant material disclosed in Japanese Patent Laid-Open No. 60-108839 and an ultraviolet curing material disclosed in Japanese Patent Laid-Open No. 55-127023. There was a resin composition. The former is composed of a condensate of an organo ladder siloxane and a functional silane having an unsaturated group, a bissilyl compound and a photosensitizer, and shows good heat resistance and good properties in a peeling test. The latter is composed of an organosiloxane having an unsaturated group and an organic peroxide, and is said to exhibit good curing characteristics in response to ultraviolet rays.

As a conventional silicone resin which can be used as a resist for microfabrication, for example, Japanese Patent Laid-Open No. 61-
There was a radiation sensitive composition disclosed in Japanese Patent No. 144639. This is composed of a siloxane oligomer, a quinonediazide compound and a phenol resin, and can be used in a multi-layer resist process for performing fine and highly accurate lithography on a substrate to be processed having irregularities. According to this, a good two-layer resist pattern can be formed.

Further, for example, in JP-A-63-16623 and JP-A-63-14432, when polyladder organosiloxane is used as an intermediate layer of a three-layer resist, that is, when a lower resist is etched by oxygen plasma, It has been proposed to use it as a mask.

[0006]

However, each of the conventional silicone resins has the following problems.

First, in those disclosed in JP-A-60-108839 and JP-A-55-127023 which are exemplified as a silicone resin usable as an insulating film, etc., a side chain of a polymer after curing is used. Since the organic group remains, even if it is a cured product, it is thermally decomposed in a high temperature process to generate gas, which may cause film damage. Therefore, it is clear that these silicone resins are inferior to inorganic SiO ₂ in heat resistance and chemical stability.

Further, JP-A-61-1446 exemplifying a silicone resin usable as a resist for fine processing.
The one disclosed in Japanese Patent No. 39 necessarily contains a quinonediazide compound and a phenol resin in addition to the siloxane oligomer, so that the silicon content is inevitably lowered. Therefore, the oxygen plasma resistance of this silicone resin coating is
Since this film is inferior to the _two- layer film, this film was not of a level having the functions of the upper layer and the intermediate layer of the three-layer resist process perfectly.

Further, as disclosed in JP-A-63-16623 and JP-A-63-14432, in the technique of using a cured film of polyladder organosiloxane as an intermediate layer in a three-layer resist process, the intermediate layer is Inorganic SiO
There is a problem in that it is inferior in plasma resistance as compared with the case of using _two films.

The present invention has been made in view of the above points. Therefore, the object of the first invention of the present application is a silicone resin which has coating properties and is more excellent in curing characteristics and thermal stability after curing than ever before. To provide. Another object of the second invention of this application is to provide a composition using the silicone resin of the first invention to make the resin more useful.

[0011]

Means and Solutions for Solving the Problems In order to achieve the object of the first invention, the inventor of this application has made various studies. As a result, it was considered that a silicone resin that finally changes into a SiO ₂ network shape or a shape close to this as shown in the following formula (4) after the treatment such as the curing step should be formed. For that purpose, a precursor as shown in the following formulas (4a) and (4b) obtained by cutting out the repeating unit of Si—O having the structure of formula (4) may be a target silicone resin constituent. I thought there was. In particular, for the purpose of obtaining the shape of the SiO ₂ network as shown in the expression (4) or a shape close to this after the treatment such as the curing step, the expressions (4a) and (4b)
It was considered ideal that the group on Si of the Si-O chain of the precursor shown in the formula was O-H as shown in the following formulas (4c) and (4d). However, (a) .Since originally, siloxane is easier to generate in equilibrium than silanol, so
It is difficult to isolate the precursors of formula (4c) and formula (4d) without causing gelation due to siloxane, (b). Considering that the ease of preparing the coating solution when using the resin is ensured, the one represented by the formula (4c) or the formula (4d) is not necessarily preferable. Therefore,
The inventor of this application has found that (4c)
It was concluded that the desired silicone resin is constituted by partially protecting the precursor silanol represented by the formula or the formula (4d).

[0012]

[Chemical 3]

[0013]

[Chemical 4]

Therefore, the silicone resin of the first invention of this application (hereinafter, may be abbreviated as "resin") is represented by the monomer unit represented by the following formula (1) and the formula (2). And a copolymer of at least two kinds of the monomer units represented by the formula (3). Alternatively, it is characterized by comprising a copolymer of a monomer unit represented by the following formula (α) and a monomer unit represented by the following formula (β). However, in the formula, R is, for example,
Various tertiary alkyl groups such as C (CH ₃ ) ₃ and —C (C ₂ H ₅ ) (CH ₃ ) ₂ , various 1-alkylphenyl groups such as α-phenethyl group, and 1,1-dialkylphenethyl groups Is. In addition, the silanol content (in the copolymer, mol% represented by OR / (OR + OH))
Is 10 to 90 mol%. The reason for this is that when the silanol content is lower than 10 mol%, condensation in the heat treatment does not occur effectively, and when it is higher than 90 mol%, problems occur in storage stability. However, how much the silanol content falls within the above range should be determined in consideration of the balance between the purpose of use of the silicone resin and the storage stability. For example, when this resin is used in combination with an acid generator as in the second invention described later, the silanol content can be set to a relatively low value within the range of 10 to 90 mol%. The copolymer referred to in the first invention may be any of random, block, and alternating copolymers.

[0015]

[Chemical 5]

[0016]

[Chemical 6]

According to the constitution of the first invention, a silicone resin comprising a copolymer having a structural part in which silanol is partially protected in the form of Si--O--R is obtained. And, in this resin, the silanol content is 10 to 90%.
Since it has been optimized, it is possible to prepare a coating solution with a suitable solvent, and further, since the formation of siloxane is suppressed in a normal storage state, a coating solution in a constant state can be always provided. Therefore, this resin can be applied onto a semiconductor substrate or the like by, for example, a spin coating method. In addition, as a solvent for preparing a coating solution, dimethylformamide, 2
-Ethyl methoxyacetate, methyl isobutyl ketone (MI
BK), cellosolve acetate, methyl cellosolve acetate, dioxane and the like.

Further, in the resin of the present invention, the silanol moiety is condensed by an appropriate heat treatment. As a result, it is considered that a SiO ₂ network as shown in the above formula (4) or a shape close to this is formed. Therefore, a cured product having a structure very close to that of SiO ₂ can be obtained by heat treatment at a relatively low temperature.

The silicone resin (copolymer) of the first invention can be obtained, for example, by hydrolyzing a monosilane having a corresponding protecting group R. For example, when the protective group R in the above formulas (1) and (3) is a t-butyl group, the silicone resin is diacetoxydi-
Obtained by hydrolyzing t-butoxysilane. The silanol content of the silicone resin of the first invention can be controlled by the conditions of hydrolysis.

Further, the silicone resin composition of the second invention of this application (hereinafter, may be abbreviated as "composition").
Is characterized by containing the silicone resin of the first invention and an acid generator which decomposes to generate an acid by the action of irradiation radiation. Here, radiation means light, electron beam,
It refers to X-rays, ion beams, or the like.

According to the constitution of the second aspect of the present invention, when the composition is entirely irradiated with radiation, the acid generator generates an acid in various places of the composition, and the acid acts on the OR bond of the silicone resin. Since this R group is eliminated, the side chain of the silicone resin becomes almost silanol. When appropriate heat is applied to the composition in such a state, silanol condensation occurs,
As a result, it is considered that a SiO ₂ network as shown in the above formula (4) or a shape close to this is formed. Therefore, a cured product having substantially the same structure as SiO ₂ can be obtained. In the case of the second invention, the removal of the R group is effectively carried out, so that it is possible to expect better conversion of SiO ₂ than the first invention.

When the protective group R in the above formulas (1) and (3) is a t-butyl group, the composition containing the silicone resin and the acid generator is cured by the following formula (5). Thought to be something like.

[0023]

[Chemical 7]

Further, when the composition of the second invention is selectively irradiated with radiation, the acid generator in the irradiated portion generates an acid, and the acid further forms an OR bond in the silicone resin in the irradiated portion. It acts and cleaves this R group, so that silanol is generated at this portion. Therefore, in the radiation-irradiated portion of the composition, silanols are condensed with each other and gelation occurs, so that this portion becomes insoluble in the developing solution. For this reason,
This composition can be used as a negative resist.

Here, in this composition, the insolubilization of the silicone resin in the radiation-irradiated portion is caused by the action of a slight amount of acid from the acid generator, and therefore the exposure amount when exposing the composition is acid. The composition is highly sensitive because it requires an exposure amount capable of generating a desired (catalytic amount) acid from the generator. In using this composition, the film of the composition is irradiated with radiation, and then the sample is subjected to heat treatment, so that the action of the acid generator in the irradiation portion can be enhanced.

As the acid generator contained in the composition of the second invention, various conventionally known ones can be used. However, hydrohalic acid is not very suitable because it has a weak catalytic action. For example, various onium salts represented by the following formulas (Ia) to (Ik), the following formula (IIa) to
Various p-toluenesulfonates represented by the formula (IIc), various trichloromethyl-substituted triazines represented by the following formulas (IIIa) to (IIIg), and the following formula (IV
Various trichloromethyl-substituted benzenes represented by a) or (IVb) are preferable because they generate an acid stronger than hydrohalic acid.

[0027]

[Chemical 8]

[0028]

[Chemical 9]

[0029]

[Chemical 10]

[0030]

[Chemical 11]

[0031]

[Chemical formula 12]

The above-mentioned acid generators are commercially available or, for example, JV Crivel (JV Cri).
Velo) [Journal of Polymer Science, Polymer Chemistry Edition (J. Polymer Sci., Polymer C
hem. Ed. , 18, 2677 (1980)] and [22, 69 (1984)].

The desired acid action can be obtained by adding 0.01% or more of these acid generators to the weight of the silicone resin used. However, if the amount is too large, the coating film of the composition may become brittle.
It is advisable to add it in an amount in the range of wt%, preferably 0.05 to 30 wt%.

[0034]

EXAMPLES Examples of the silicone resin of the first invention and examples of the composition of the second invention of this application will be described below. However, the materials used and the numerical conditions such as the amount thereof, the processing time, the processing temperature, and the film thickness mentioned in the following description are only suitable examples within the scope of these inventions. Therefore, these inventions are not limited to these conditions. Further, each of the following examples is based on the above formula (1),
This is an example of the case where R in the formulas (3) and (β) is —C (CH ₃ ) ₃ .

1. Description of first invention 1-1. First Example At least two kinds of monomers among the monomer unit represented by the above formula (1), the monomer unit represented by the formula (2) and the monomer unit represented by the formula (3). A silicone resin composed of a unit copolymer (single chain polysiloxane) having a silanol content of 60 mol% is synthesized as follows.

Diacetoxy-t-butoxysilane 5.8
g (20 mmol) of tetrahydrofuran (THF) 1
Dissolve in 00 ml and cool the solution to 0 ° C. To this solution are added 0.21 g of triethylamine and 3.6 ml of water. After stirring this for 1 hour at room temperature, the temperature is raised to 80 ° C. and the reaction is performed for 12 hours. After cooling this, water 10
The polymer produced is extracted by adding 0 ml. The organic layer is dried over magnesium sulfate overnight and then filtered through Celite. The solvent is distilled off from the filtrate under reduced pressure to a total volume of about 50 ml, which is then poured into n-hexane. The precipitate thus produced is filtered off and 2 g of powder are obtained.

In nuclear magnetic resonance (NMR) of this powder, the peak derived from t-butyl group in heavy DMF was δ1.3.
In addition, a peak derived from silanol was observed near δ 4.0. The intensity ratio between the two was 40:60. In the IR (infrared) spectrum, the wave number is 11
Strong absorption based on siloxane was observed at 50 cm ^-1 ,
C-C of t-butyl group at wave numbers of 1360 and 1390 cm ^-1
Absorption of the bond was observed. The result of molecular weight measurement by gel permeation chromatography (GPC) is Mw = 260.
00 and Mw / Mn = 1.8.

Next, 30% (weight / volume%) dimethylformamide (DM) of the silicone resin of the first embodiment was used.
F) Prepare the solution. The solution thus prepared is applied onto a silicon wafer by spin coating, and then the silicon wafer is baked at a temperature of 150 ° C. for 5 minutes. The IR spectrum of the coating on the silicon wafer after baking, the absorption of siloxane bonds in the vicinity of a wave number of 1100 cm ^-1 is a t- butyl group at a wavenumber 1360,1390cm ^-1 C
The absorption of −C bond was observed, but the wavenumber was 3300
No absorption based on OH of silanol was observed near cm ^-1 . Further, this film is a non-polar organic solvent such as benzene, toluene and monochlorobenzene, a polar organic solvent such as DMF, alcohol and ethyl 2-methoxyacetate,
It was found to be completely unaffected by water and hydrochloric acid. From these, it is understood that this silicone resin is gelated by heating and is partially converted into SiO ₂ . However, a part of the t-butyl group remains.

1-2. Second Example At least two monomers selected from the monomer unit represented by the above formula (1), the monomer unit represented by the formula (2), and the monomer unit represented by the formula (3). A silicone resin composed of a unit copolymer (single chain polysiloxane) having a silanol content of 30 mol% is synthesized as follows.

Diacetoxy-t-butoxysilane 5.8
g (20 mmol) is dissolved in 100 ml of THF and the solution is cooled to 0 ° C. To this solution are added 0.21 g of triethylamine and 3.6 ml of water. After stirring this at room temperature for 1 hour, the temperature was raised to 80 ° C. and the reaction was carried out for 6 hours. After cooling this, 100 ml of water is added thereto to extract the produced polymer. The organic layer is dried over magnesium sulfate overnight and then filtered through Celite. The solvent is distilled off from the filtrate under reduced pressure to a total volume of about 50 ml, which is then poured into n-hexane. The precipitate thus produced is filtered off and 2 g of powder are obtained.

According to NMR of this powder, t-
A peak derived from a butyl group was observed at δ1.3, and a peak derived from silanol was observed near δ4.0.
The intensity ratio of the two was 70:30. Also, I
In the R spectrum, strong absorption due to siloxane was observed at a wave number of 1150 cm ^-1 , and wave numbers of 1360 and 1390c were observed.
Absorption of C—C bond of t-butyl group was observed in m ⁻¹ .
The molecular weight measured by GPC is Mw = 1200.
0, Mw / Mn = 1.4.

1-3. Third Example Copolymer (ladder polysiloxane) of a monomer unit represented by the above formula (α) and a monomer unit represented by the above formula (β), wherein the silanol content is 70 mol% The silicone resin composed of is synthesized as follows.

20 g of tetraacetoxysilane (76 mm
ol) is dissolved in 100 ml of THF and the solution is cooled to 0 ° C. To this solution, potassium t-butoxide 8.5
What melt | dissolved g (76 mmol) in THF50ml is dripped in 10 minutes. Next, the solution is stirred for 1 hour, then removed from the cold bath and allowed to naturally warm to room temperature. next,
The solution is heated and refluxed for 12 hours. After cooling, TH
Evaporate F under reduced pressure. Next, this is dissolved in 300 ml of methyl isobutyl ketone (MIBK), 2.3 g of triethylamine is added to this solution, and the mixture is cooled to 0 ° C. next,
41 ml of water is added dropwise to this solution over 30 minutes. The solution is stirred for 1 hour, then removed from the cold bath and allowed to warm to room temperature. Next, the solution is heated and refluxed for 5 hours. After cooling this, 100 ml of water is added thereto to extract the produced polymer. The organic layer is dried over magnesium sulfate overnight and then filtered through Celite. The solvent is distilled off from the filtrate under reduced pressure to a total volume of about 50 ml, which is then poured into n-hexane. The precipitate generated by this is collected by filtration and is 7 g.
Of powder is obtained.

According to the NMR of this powder, t-
A peak derived from a butyl group was observed at δ1.13, and a peak derived from silanol was observed at around δ4.0. And the intensity ratio of both was 30:70. Further, in the IR spectrum, strong absorption based on siloxane was observed at a wave number of 1150 cm ^-1 , and wave numbers of 1360 and 13 were observed.
Absorption of C—C bond of t-butyl group was observed at 90 cm ⁻¹ . The result of the molecular weight measurement by GPC is Mw = 4
2000, Mw / Mn = 1.6.

2. Description of Second Invention Next, examples of the composition of the second invention containing a silicone resin and an acid generator will be described.

2-1. Preparation of Composition 1.0 g of the silicone resin of the second embodiment of the first invention (single chain polysiloxane having a silanol content of 30 mol%),
0.10 g of triphenylsulfonium trifluoromethanesulfonate (represented by the above formula (Ig)) as an acid generator was dissolved in isoamyl acetate as a solvent to prepare a composition of Example (a coating solution of the composition). Prepare.

2-2. Description of formation of SiO ₂ Next, the coating solution of the composition thus prepared is coated on a silicon wafer by spin coating. Next, this silicon wafer is soft-baked at a temperature of 60 ° C. for 1 minute using a hot plate to form a 0.5 μm thick film of the composition of the example on the silicon wafer. Next, the entire surface of this film is irradiated with Xe-Hg lump light with an output of 500 W for 10 seconds by a PLA501 aligner manufactured by Canon Inc. Then, the silicon wafer is baked at a temperature of 150 ° C. for 5 minutes to obtain a cured film.

In the IR spectrum of this cured film, nothing other than absorption of siloxane bonds near the wave number of 1100 cm ^-1 was observed. Also, this film is benzene, toluene,
It was found to be completely unaffected by non-polar organic solvents such as monochlorobenzene, DMF, alcohol, polar organic solvents such as 2-methoxyethyl acetate, water, hydrochloric acid and the like. From these facts, this silicone resin is substantially SiO 2.
It is presumed that it has changed to ₂ .

Further, even if the silicon wafer having this cured film was baked at a temperature of 500 ° C. for 2 hours, no crack was observed in this film.

2-3. Description of example of use as a resist As a lower layer, a thermosetting resist layer with a thickness of 1 μm (MP
1400-31 Shipley resist) is formed on a silicon wafer. Next, 2-1. The coating solution of the composition prepared in the above section was applied by a spin coating method, and this was soft-baked at a temperature of 60 ° C. for 1 minute using a hot plate to form a film having a thickness of 0.2 μm of the composition of Example on the lower layer. Form a film.

Next, a considerable number of evaluation figures are drawn on this sample by using an electron beam drawing apparatus (ELS3300 manufactured by Elionix Co., Ltd.) under the condition of an acceleration voltage of 20 KV while changing the exposure amount. The exposed sample is baked on a hot plate at a temperature of 120 ° C. for 5 minutes. The sample is then developed with DMF for 30 seconds and rinsed with xylene for 30 seconds. As a result, a resist pattern in which the electron beam non-irradiated portion of the film was dissolved in the developing solution was obtained. A sample for a scanning electron microscope (SEM) was prepared from this sample and observed, and it was found that a line and space pattern of 0.5 μm was resolved at an exposure dose of 1.5 μC / cm ^2. It was

Further, according to the procedure described above, the formation of the lower layer on the silicon wafer and the formation of the 0.5 μm line-and-space pattern of the composition of the example on the lower layer are performed again. After that, this sample was manufactured by Nichiden Anelva DE
Using a dry etcher called M451, oxygen plasma etching is performed for 20 minutes under the conditions of an oxygen gas flow rate of 50 sccm, an RF power density of 0.12 W / cm ² and a gas pressure of 1.3 Pa.

This plasma-etched sample is SEM
When observed with, the thickness was about 1.1 μm, 0.5 μ
It was found that the line and space pattern of m was formed in a substantially vertical shape.

2-2. As is clear from the explanation of the section, it can be understood that the composition of the second invention can form a film substantially the same as the SiO ₂ film, and 2-3. As is clear from the explanation of the section, it can be understood that the composition of the second invention can be used as a resist and also as a resist which also serves as an oxygen plasma etching mask.

Although the respective embodiments of the silicone resin and the composition thereof of the present invention have been described above, the present invention is not limited to these embodiments.

For example, in each of the above embodiments, (1),
In the formulas (3) and (β), R is a t-butyl group [-C (CH ₃ ).
₃ ] has been described. However, even when R in the formula (1) is another tertiary alkyl group, 1-alkylphenethyl group, or 1,1-dialkylphenethyl group, the same effects as in the example can be obtained.

Also, even when the acid generator is a suitable one other than those used in the examples, for example, the above-mentioned examples, the same effects as in the above-mentioned examples can be obtained.

Further, although the Xe-Hg lamp and the electron beam were used as the radiation for the exposure in the above-mentioned embodiment of the second invention, the radiation used for the exposure is not limited to this.

[0059]

As is apparent from the above description, according to the silicone resin of the first invention of this application, a SiO ₂ film is formed by coating (for example, spin coating) on a base and by heat treatment at a relatively low temperature. A heat resistant film having a close structure can be formed. Therefore, for example, the passivation film of the semiconductor device can be formed of this silicone resin, so that the process of forming the passivation film can be simplified.

[0060] Further, according to the composition of the second invention of this application, it can form a heat-resistant film of the first invention and the same or closer to the SiO ₂ film structure. Furthermore, it can also be used as a highly sensitive resist by performing selective irradiation of radiation. Therefore, it can also be used as a resist for the two-layer resist method which has more excellent O ₂ plasma resistance than before. It can also be used as an intermediate layer for a three-layer resist method.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03F 7/004 503 7/028 7/038 505 H01L 21/027

Claims (3)

[Claims] 1. A monomer unit represented by the following formula (1):
A silicone resin comprising a copolymer of a monomer unit represented by the formula (2) and at least two monomer units of the monomer unit represented by the formula (3) (however, In the formula, R is a tertiary alkyl group, a 1-alkylphenethyl group or a 1,1-dialkylphenethyl group, and the silanol content is 10 to 90 mol%.). [Chemical 1] 2. A silicone resin comprising a copolymer of a monomer unit represented by the following formula (α) and a monomer unit represented by the following formula (β), wherein R Is the third
Alkyl group, 1-alkylphenethyl group or 1,1-
It is a dialkylphenethyl group. The silanol content is 10 to 90 mol%. ). [Chemical 2] 3. A silicone resin composition comprising the silicone resin according to claim 1 or 2 and an acid generator that decomposes to generate an acid by the action of irradiation radiation.