JP2001279163A - Coating fluid for forming siliceous coating film, method for producing siliceous coating film, siliceous coating film, semiconductor element using the same, and multi- layer printed wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating fluid that can easily form a low-permittivity siliceous film having sufficient adhesion to the adjoining films and undergoing no peeling in a CMP process in a Cu damascening process in good yields a method for producing a siliceous coating film from the coating fluid, a signal- delay-free, high-grade, high-reliability semiconductor element, and a signal-delay- free, high-grade, high-reliability multi-layer wiring board. SOLUTION: Provided are a coating fluid for forming a siliceous coating film, containing (A) a polysiloxane having a content of organic groups of 1-50% and having a content of unsaturated organic groups of 1-50% based on all of the organic groups and (B) a solvent, a method for forming a siliceous coating film comprising coating a substrate with the coating fluid and drying the wet film, a siliceous coating film obtained by the method, a semiconductor element having the siliceous coating film, and a multi-layer wiring board having the siliceous coating film as the interlayer insulation film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating solution for forming a silica-based coating, a method for producing a silica-based coating, a silica-based coating, a semiconductor device using the same, and a multilayer wiring board. The present invention relates to a coating solution for forming a silica-based coating, a method for producing a silica-based coating using the same, a silica-based coating, a semiconductor device, and a multilayer wiring board.

[0002]

2. Description of the Related Art With the miniaturization of wiring due to the increase in the speed of LSIs, an increase in signal delay time due to an increase in capacitance between wirings has become a problem. Conventionally, C having a relative dielectric constant of about 4.2
Although a SiO ₂ film formed by the VD method has been used as an interlayer insulating film, a film having a lower dielectric constant is required in order to reduce the inter-wiring capacitance of the device and improve the operation speed of the LSI.

[0003] As a low dielectric constant film which is currently put into practical use, SiO 2 formed by a CVD method having a relative dielectric constant of about 3.5 is used.
F film. As an insulating film having a relative dielectric constant of 2.5 to 3.0, organic SOG (Spin On Glass), an organic polymer, or the like is used. For an insulating film having a relative dielectric constant of 2.5 or less, a porous material having a void in the film is used. It is considered influential and is being actively studied.

[0004] With the development of multilayer wiring of LSI, CMP (Chemical Mechanical Polishing) has been used for global flattening.
Is becoming mandatory. In order to cope with this CMP process, an insulating film is required to have low dielectric constant characteristics, mechanical strength and adhesion to an adjacent film as important characteristics. Relative dielectric constant 3.0
Organic SO which has been variously studied as a low dielectric constant film of less than
G: The organic polymer is SiO ₂ formed by the CVD method.
Although the relative dielectric constant is lower than that of the film and the SiOF film, the problem is that the adhesion to the adjacent film is low. This insufficient adhesion causes separation between the insulating film and the adjacent film in the CMP process. In the case of a low dielectric constant film having a relative dielectric constant of 2.6 or less, adhesion to an adjacent film is further reduced.

[0005]

SUMMARY OF THE INVENTION The inventions described in claims 1 to 4 have a sufficient adhesion to an adjacent film, and have a
An object of the present invention is to provide a coating liquid for forming a silica-based film, which can easily form a low-dielectric-constant silica-based film that does not peel off in a P step (particularly, a CMP step in a Cu damascene step, the same applies hereinafter) with good yield. The invention according to claim 5 has a sufficient adhesion to an adjacent film, and the
An object of the present invention is to provide a method for producing a silica-based coating film, which can easily form a low-dielectric-constant silica-based coating film that does not peel off in a process with high yield.

According to a sixth aspect of the present invention, there is provided a silica-based coating having a low dielectric constant, which has sufficient adhesion to an adjacent film and does not peel off in a CMP process of an LSI. A seventh aspect of the present invention is to provide a high-quality and high-reliability semiconductor device having no signal delay. An eighth aspect of the present invention is to provide a high-quality and high-reliability multilayer wiring board having no signal delay.

[0007]

According to the present invention, there is provided (A) a polysiloxane having an organic group content of 1 to 50%, in which an organic group content having an unsaturated bond is 1 to 50%; (B) The present invention relates to a coating solution for forming a silica-based film, comprising a solvent. Further, the present invention further comprises (C) a thermally decomposable polymer in addition to the components (A) and (B),
The coating liquid for forming a silica-based film, wherein the component (B) is a solvent that uniformly dissolves the components (A) and (C).

[0008] The present invention also relates to the above-mentioned coating solution for forming a silica-based film, wherein the organic group having an unsaturated bond is a vinyl group. The present invention also relates to a silica-based coating liquid for forming a silica-based coating, wherein the relative dielectric constant of the silica-based coating formed from the silica-based coating-forming coating liquid is 2.6 or less. The present invention also relates to a method for producing a silica-based coating, which comprises applying the above-mentioned coating liquid for forming a silica-based coating on a substrate and drying the coating.

[0009] The present invention also relates to a silica-based coating obtained by the above-mentioned method for producing a silica-based coating. The present invention also relates to a semiconductor device having the above-mentioned silica-based coating. The present invention also relates to a multilayer wiring board using the above-mentioned silica-based coating as an interlayer insulating film.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polysiloxane in the present invention is, for example, a compound represented by the general formula (I)

Embedded image (Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 14 carbon atoms, R ² represents an organic group having an unsaturated bond having 2 to 12 carbon atoms, and R ³ represents a carbon atom. Numbers 1-6
Wherein n and m are integers selected so as to satisfy 0 ≦ n + m ≦ 3) by hydrolysis-condensation polymerization of an alkoxysilane represented by the following formula: It is preferable to use a combination of an alkoxysilane in which n is 0 and m is 1 to 3 and an alkoxysilane in which m is 0 and n is 1 to 3 in order to form a uniform film.

The alkyl group having 1 to 18 carbon atoms includes, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, amyl group, isoamyl group, Examples include a hexyl group, a cyclohexyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, and an octadecyl group. Examples of the aryl group having 6 to 14 carbon atoms include a phenyl group, a tolyl group, an aminophenyl group, and a naphthyl group. Among these, a methyl group and a phenyl group are preferred, and a methyl group is more preferred.

Examples of the organic group having an unsaturated bond having 2 to 12 carbon atoms include alkenyl groups such as vinyl group, allyl group, cyclohexenyl group, methacryloxy group and methacryloxypropyl group, ethynyl group and 5-hexenyl. And alkynyl groups such as a group, and substituents containing a carbonyl such as a 3-acryloxypropyl group, a methacryloxypropyl group, and an acetate group. Among these, a vinyl group and an allyl group are preferred, and a vinyl group is more preferred.

In the present invention, the content of the organic group is expressed by the following formula (1).

(Equation 1) (In the formula (1), R ¹ , R ² , m and n are represented by the general formula (I)
Is the same as the above). The content of the organic group having an unsaturated bond among the organic groups is represented by the following formula (2).

(Equation 2) (In the formula (2), R ¹ , R ² , m and n are represented by the general formula (I)
Is the same as the above).

In the present invention, the organic group content is 1 to 50%, preferably 5 to 40%, more preferably 10 to 30%. If the organic group content is less than 1%, the relative permittivity cannot be sufficiently reduced, and if it exceeds 50%, the adhesion is poor. The content of the organic group having an unsaturated bond in the organic group is 1 to 50.
%, Preferably 5 to 30%, more preferably 10 to 20%. When the content of the organic group having an unsaturated bond among the organic groups is less than 1%, the adhesion is poor, and when it exceeds 50%, the relative permittivity cannot be sufficiently reduced.

The hydrolysis and condensation of the alkoxysilane represented by the general formula (I) can be carried out by a conventional method.
There is a method of reacting an alkoxysilane by adding water in the presence of a solvent and a catalyst. In this case, heating may be performed if necessary. As the catalyst, inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and organic acids such as formic acid, oxalic acid and acetic acid can be used. Usually, the molecular weight of the product is preferably set in the range of 500 to 10,000 in terms of standard polystyrene equivalent weight average molecular weight determined by gel permeation chromatography (GPC). Then, if necessary, water and a solvent existing in the system may be removed by distillation or the like, and the catalyst may be removed with an ion exchange resin or the like.

Examples of the solvent (B) in the present invention include alcohol solvents such as methanol, ethanol, propanol and butanol, acetate solvents such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate, and ethylene glycol monomethyl acetate. Acetate solvents such as ethylene glycol diacetate, N
Examples thereof include amide solvents such as -methyl-2-pyrrolidone, glycol ether solvents, and lactone solvents such as γ-butyrolactone, and these are used alone or in combination of two or more.

(C) When using a thermally decomposable polymer,
It is preferable that the solvent (B) is a solvent that uniformly dissolves the components (A) and (C). (B) The amount of the solvent used is
The amount is preferably such that the total concentration of (A) the polysiloxane and, if necessary, (C) the thermally decomposable polymer is 1 to 25% by weight.

(C) optionally used in the present invention
Examples of the thermally decomposable polymer include vinyl ester polymers such as polyvinyl acetate, methacrylate ester polymers such as polymethyl methacrylate, acrylate ester polymers such as polymethyl acrylate, polyvinyl alcohol, polyethylene imine, fluororesin, and the like. Is raised. Among them, polymethyl methacrylate and a copolymer of methyl methacrylate and a monomer copolymerizable therewith are preferred. These are used alone or in combination of two or more.

When (C) the thermally decomposable polymer is used, its amount is preferably 3 to 3 parts per 100 parts by weight of the polysiloxane (A) from the viewpoints of lowering the dielectric constant and mechanical strength of the obtained silica coating. 100 parts by weight, preferably 10 parts by weight.
The amount is more preferably from 80 to 80 parts by weight, particularly preferably from 20 to 80 parts by weight, and particularly preferably from 40 to 70 parts by weight.

As a method for producing a silica-based film (organic SOG film), a spin coating method is generally used.
For example, after spin coating, prebaking is performed on a hot plate, and finally, final curing is performed using a furnace. Pre-baking is performed at a temperature of 50 to 300 ° C. for about 1 to 180 minutes,
It is carried out stepwise from a low temperature using a single hot plate. The final curing temperature is 300 to 450 ° C. for about 1 to 180 minutes, and this atmosphere is usually a nitrogen atmosphere in order to prevent decomposition of organic groups. At this time, at the time of heating at 300 to 400 ° C., the (C) thermally decomposable polymer is thermally decomposed and disappears.

By applying the silica-based coating produced according to the present invention as an interlayer insulating film of a semiconductor element and a multilayer wiring board, excellent properties such as a low dielectric constant, preferably a low dielectric constant of 2.6 or less and a high insulation resistance are obtained. High performance such as reduction of electrical characteristics and signal propagation delay time can be achieved.

The semiconductor element in the present invention includes a diode, a transistor, a compound semiconductor, an individual semiconductor such as a thermistor, a varistor, and a thyristor, a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), EPR
OM (Erasable Programmable, Read Only Memory), Mask ROM (Mask Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), storage elements such as flash memory, microprocessor, Theoretical circuit elements such as DSP and ASIC,
MMIC (monolithic microwave integrated circuit)
And a photoelectric conversion element such as a light-emitting diode and a charge-coupled device.

The multilayer wiring board in the present invention includes a high-density wiring board such as an MCM. By applying a coating film formed from the composition of the present invention as an interlayer insulating film, high reliability can be achieved at the same time as high performance such as reduction of signal propagation delay time as described above.

[0024]

The present invention will be described below with reference to examples. In the measurement of the relative dielectric constant, a wafer having a cured film of 0.5 to 0.6 μm formed on a low-resistance silicon wafer of 0.1Ω or less was used. Forming an Al electrode on the cured film,
The capacitance of the capacitor formed of the electrode and the Si wafer was measured, and the relative dielectric constant was calculated from the film thickness and the electrode area. The capacity measurement was performed at 1 MHz. The evaluation of the adhesiveness with the adjacent film was performed on a silicon wafer with a thickness of 0.4 to 0.6 μm.
Of a silica-based film (insulating film) having a thickness of 0.1
A cross-cut test (tape peeling test) was performed on a μm SiO ₂ film (CVD method) or a film laminated with an aluminum film according to JIS K5400, and the degree of peeling was determined.

Example 1 124.6 g of CH ₃ Si (OCH ₂ CH ₃ ) ₃ and CH ₂ =
56.4 g of CHSi (OCH ₂ CH ₃ ) ₃ was dissolved in 120 g of propylene glycol monopropyl ether, and a mixed solution of 54 g of water and 0.1 g of nitric acid was added dropwise over 1 hour, followed by further reaction at room temperature for 24 hours. A polysiloxane solution was obtained (the organic group content of the polysiloxane was 26.3%).
Wherein the content of the organic group having an unsaturated bond is 11.5%).

Next, a γ-butyrolactone solution of polymethyl methacrylate (concentration: 20% by weight) was mixed with a polysiloxane solution at a weight ratio of 7: 3, and left at room temperature for 3 days to form a silica-based film. Coating solution. The coating solution was applied on a 6-inch silicon wafer at 2000 min ^-1 using a spinner, and then applied at 150 ° C. for an additional 25 minutes.
Each was dried for 1 minute on a hot plate controlled at 0 ° C., and then baked in an electric furnace at 400 ° C. for 1 hour in nitrogen. As a result, a colorless, transparent and crack-free film was obtained. The thickness of this film was measured and found to be 0.50 μm.

On this film, an aluminum film of 0.1 μm
Was formed by a sputtering method, and the dielectric constant of the sample was measured at a frequency of 1 MHz using an LF impedance meter, and was 2.6. On this film, a 0.1 μm thick Si
JIS K is applied to O ₂ film (CVD method)
When a grid test (tape peeling test) was performed according to 5400, no peeling was observed.

Comparative Example 1 178 g of CH ₃ Si (OCH ₂ CH ₃ ) ₃ was dissolved in 400 g of propylene glycol monopropyl ether, and a mixed solution of 50 g of water and 0.1 g of nitric acid was added dropwise over 1 hour. For 24 hours to obtain a polysiloxane solution (the organic group content of the polysiloxane is 22.4%, in which the organic group content having an unsaturated bond is 0%).
%) As a coating solution for forming a silica-based film. The coating solution was applied on a 6-inch silicon wafer at 2,000 min ^-1 using a spinner, and then heated at 150 ° C. for further 250 minutes.
After drying on a hot plate controlled at a temperature of 1 ° C. for 1 minute and then firing in an electric furnace at 400 ° C. for 1 hour in nitrogen, a colorless, transparent and crack-free film was obtained. The thickness of this film was measured and found to be 0.50 μm.

[0029] An aluminum coating of 0.1 µm on this coating
Was formed by a sputtering method, and the dielectric constant of the sample was measured at a frequency of 1 MHz using an LF impedance meter.
It was 8. Next, each measurement was performed in the same manner as in Example 1, and the results are shown in Table 1.

[0030]

[Table 1]

[0031]

The coating liquid for forming a silica-based film according to any one of claims 1 to 4 has a sufficient adhesion to an adjacent film, and is used for a CMP process of an LSI (particularly a CMP process in a Cu damascene process, the same applies hereinafter). In this method, a low dielectric constant silica-based coating which does not cause peeling can be easily formed with high yield. The method for producing a silica-based coating according to claim 5 is capable of easily forming a low-dielectric-constant silica-based coating having sufficient adhesion to an adjacent film and not causing peeling in an LSI CMP process with good yield. is there.

The silica-based coating according to the sixth aspect has a low dielectric constant, which has sufficient adhesion to an adjacent film and does not peel off in the CMP process of the LSI. The semiconductor device according to claim 7 is of high quality and high reliability without signal delay. The multilayer wiring board according to claim 8 is of high quality and high reliability without signal delay.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/90 Q (72) Inventor Shigeru Nobe 4-3-1-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical (72) Inventor Kazuhiro Enomoto 4-3-1-1, Higashi-cho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. No.F-term (reference) at Hitachi Chemical Co., Ltd. Yamazaki Office 4G072 AA25 BB09 FF09 HH30 JJ16 LL13 LL15 MM37 NN21 RR05 SS01 UU01 4J038 CD101 CD102 CF021 CF022 CG141 CG142 DL061 DL062 FA241 FA242 GA02 GA15 JA12 JA26 JA54 LA03 MA07 MA10 NA21 PA19 PB09 PC08 5F033 HH11 MM01 RR04 RR25 SS22 VV00 VV16 XX14 XX24 XX27

Claims (8)

[Claims] (A) The organic group content is from 1 to 50%, and the organic group content having an unsaturated bond is from 1 to 50%.
A coating liquid for forming a silica-based film, comprising 50% of a polysiloxane and (B) a solvent. 2. The composition further comprises (C) a thermally decomposable polymer in addition to the components (A) and (B), and the component (B) uniformly dissolves the components (A) and (C). The coating solution for forming a silica-based film according to claim 1, which is a solvent. 3. The coating solution for forming a silica-based film according to claim 1, wherein the organic group having an unsaturated bond is a vinyl group. 4. A coating liquid for forming a silica-based coating, wherein the silica-based coating formed from the coating liquid for forming a silica-based coating according to claim 1, 2, or 3 has a relative dielectric constant of 2.6 or less. 5. A method for producing a silica-based coating, comprising applying the coating liquid for forming a silica-based coating according to claim 1, 2 or 3, onto a substrate, and drying. 6. A silica-based coating obtained by the method according to claim 5. 7. A semiconductor device having the silica-based coating according to claim 6. 8. A multilayer wiring board using the silica-based coating according to claim 7 as an interlayer insulating film.