JP2000223487A - Silica based film, coating liquid for forming silica based film and semiconductor device employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability of a semiconductor device by subjecting a silane compound represented by a specified formula to hydrolytic condensation polymerization thereby lowering permittivity. SOLUTION: A silane compound represented by formula I (in the formula, R1 is an 1-6C alkyl group, an aryl group or a fluoroalkyl group, R2 is an alkylene group or an arly group, X is a halogen or alkoxy group, and n is an integer of 0-2) is subjected to hydrolytic condensation polymerization thus obtaining a coating liquid for forming a silica based film. As a method for lowering the permittivity of siloxane polymer, lowering of the intermolecule polarization or the density of a silica based film being obtained through hardening of siloxane polymer is employed effectively. From that view point, a method for introducing an organic group into polymer framework is employed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating solution for forming a silica-based film, a silica-based film, and a semiconductor device.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor manufacturing, with the miniaturization of devices, the dielectric constant of an interlayer insulating flattening film between wirings made of aluminum or the like has been increased to increase the capacitance between wirings and delay signal propagation of wirings. Etc. is a problem. Examples of commonly used interlayer insulating films include, for example, BPSG (boron-phosphosilicate glass), P-TEOS (plasma-tetraethoxysilane), O ₃ -TEOS (ozone-tetraethoxysilane), SOG ( Although these insulating films usually have a relative dielectric constant (ε) of 4 or more, it is necessary to lower the dielectric constant of the interlayer insulating film in order to solve the above problem. SOG in this
As is well known, a siloxane polymer formed by a hydrolysis reaction of a tetrafunctional silane such as tetraethoxysilane is well known, but the relative dielectric constant of this chemical species is 5 or more, and the dielectric constant of the siloxane polymer should be lowered. Is desired.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a coating liquid for forming a silica-based film, a silica-based film, and a semiconductor using the silica-based film, which can improve the reliability of a semiconductor device by lowering the dielectric constant. An apparatus is provided.

[0004]

The present invention relates to a compound of the formula (I)

Embedded image (Wherein, R ¹ represents an alkyl group, aryl group or fluoroalkyl group having 1 to 6 carbon atoms, R ² represents an alkylene group or an aryl group, X represents a halogen or an alkoxy group, and n represents 0 to 2 The present invention relates to a coating solution for forming a silica-based film, which is obtained by subjecting a silane compound represented by The present invention also relates to a silica-based coating obtained by applying the above-described coating liquid for forming a silica-based coating on a substrate, drying the coating at 50 to 250 ° C, and then heating and curing at 200 to 600 ° C in a nitrogen atmosphere. The present invention also relates to a semiconductor device having the silica-based coating formed thereon.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a method of lowering the dielectric constant of a siloxane polymer, it is effective to lower the polarization between constituent molecules and to lower the density of a silica-based film obtained by curing the siloxane polymer. From this viewpoint, a method of introducing an organic group into the polymer skeleton is effective.

The silane compound represented by the general formula (I) is specifically described

Embedded image (Where Ph represents a paraphenylene group) and the like;

Embedded image And the like.

[0007] These silane compounds may be used alone or in combination of two or more. The hydrolysis and condensation reactions of these silane compounds can be performed by well-known and known methods. In the case of alkoxysilane, there is a method in which water is added to the alkoxysilane in the presence of a solvent and a catalyst to cause a hydrolytic condensation reaction. In this case, heating may be performed as needed. 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. Next, water and a solvent present 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. In the case of chlorosilane, there is a method in which water is added to chlorosilane to cause a hydrolytic condensation reaction. The addition amount of the catalyst is preferably in the range of 0.001 to 0.1 mol based on 1 mol of the total amount of the alkoxysilane and the halogenated silane.
The amount of water to be added is preferably in the range of 0.1 to 10 mol, more preferably in the range of 0.5 to 1.5 mol, per 1 mol of the total amount of the alkoxysilane and the halogenated silane.

It is preferable to use an organic solvent as a solvent in the coating solution for forming a silica-based film in the present invention. Examples of the organic solvent include alcohols such as methanol, ethanol, propanol and butanol, and acetates such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate,
Various solvents such as glycol acetate solvents such as ethylene glycol monomethyl acetate and ethylene glycol diacetate, amide solvents such as N, N-methyl-2-pyrrolidone, and glycol ether solvents are mentioned. The above is used. The amount of the solvent used is preferably such that the amount of the polysiloxane resin obtained by the above reaction is 15 to 50% by weight.

The coating solution for forming a silica-based film prepared by the above method is applied onto a substrate such as a silicon wafer mainly by spin coating. Other application methods include dip and spray. Further, glass, ceramic, metal, or the like can be used as the application substrate. After applying by these methods, it is preferable to form a silica-based coating by pre-curing at 100 to 300 ° C. and finally curing at 300 to 500 ° C. in a curing furnace. Precuring is performed for 30 seconds to 3 minutes on a hot plate, and
It is preferably performed for up to 30 minutes.

An example of the manufacturing process of the semiconductor device of the present invention will be described below. FIG. 1 is a manufacturing process diagram of a semiconductor device according to the present invention. As shown in FIG. 1A, a silica-based coating 2 is formed on a substrate 1. Next, as shown in FIG. 1B, a photosensitive resin layer 3 of a chlorinated rubber type or a phenol novolak type is formed on the silica-based coating 2, and a predetermined portion of the silica-based coating 2 is formed by a known photolithography technique. The window 4A is provided so that is exposed. Next, as shown in FIG. 1C, the silica-based coating 2 in the window 4A is selectively etched by dry etching using a fluorine-based gas such as carbon tetrafluoride. The photosensitive resin layer 3 is completely removed using an etching solution that corrodes only the photosensitive resin layer 3 without corroding the photosensitive resin layer 3. Next, as shown in FIG. 1D, a first conductive layer 5 is formed by a known metal film forming method, and the first conductive layer 5 formed as necessary is replaced with a CMP (Chemicaa1 Mechanical Polishin).
Polishing by g) method.

When forming a multilayer wiring structure having two or more layers, the above steps are repeated to form each layer. That is, there is a step (a) of forming an interlayer insulating film to be an insulating layer on the conductor layer, and steps (b) and (c) of selectively removing a predetermined portion of the coating to open a window. The step (d) of forming the conductor connected to a predetermined portion of the conductor layer will be repeated.

A surface protective layer made of an organic material such as a polyimide resin or an inorganic material such as silicon nitride is formed on the surface of the multilayer wiring structure thus manufactured. A window similar to the above windows 4A and 4B may be opened in a predetermined portion of the surface protective layer in some cases. The entire semiconductor device is usually sealed with a sealing material such as an epoxy resin.

[0013]

The present invention will be described below with reference to examples. Example 1 10 g of tetramethoxydimethyldisilmethylene was dissolved in 42 g of propylene glycol monopropyl ether, and a solution of 0.08 g of phosphoric acid dissolved in 3.0 g of water was added dropwise to this solution over 10 minutes. After stirring for 5 hours after the completion of the dropping, a polysiloxane solution (a coating solution for forming a silica-based film) was obtained. This was spin-coated on a wafer and placed on a hot plate at 150 ° C. for 30 seconds and then 250
Precured by heating at 30 ° C. for 30 seconds. Next, it was placed in a quartz furnace and cured by heating at 400 ° C. for 30 minutes in nitrogen. The relative permittivity of the cured film produced by capacitance measurement at a frequency of 10 KHz was 2.8.

Example 2 10 g of tetramethoxydimethyldisylphenylene was dissolved in 42 g of propylene glycol monopropyl ether, and a solution of 0.07 g of phosphoric acid dissolved in 2.5 g of water was added dropwise to this solution over 10 minutes. . After stirring for 5 hours after the completion of the dropping, a polysiloxane solution (a coating solution for forming a silica-based film) was obtained. This was spin-coated on a wafer and placed on a hot plate at 150 ° C. for 30 seconds and then 250
Precured by heating at 30 ° C. for 30 seconds. Next, it was placed in a quartz furnace and cured by heating at 400 ° C. for 30 minutes in nitrogen. The relative permittivity of the cured film produced by capacitance measurement at a frequency of 10 KHz was 3.0.

Comparative Example 1 10 g of tetramethoxysilane was dissolved in 42 g of propylene glycol monopropyl ether, and a solution of 0.13 g of phosphoric acid dissolved in 4.7 g of water was added dropwise to this solution over 10 minutes. After stirring for 5 hours after the completion of the dropwise addition, a polysiloxane solution was obtained. This was spin-coated on a wafer and placed on a hot plate at 150 ° C. for 30 seconds and then 25
Precured by heating at 0 ° C. for 30 seconds. Next, it was placed in a quartz furnace and cured by heating at 400 ° C. for 30 minutes in nitrogen.
The relative permittivity of the cured film produced by capacitance measurement at a frequency of 10 KHz was 6.0.

[0016]

The silica coating obtained from the coating liquid for forming a silica coating of the present invention has a low relative dielectric constant, and the semiconductor device of the present invention has the silica coating having a low relative dielectric constant as an interlayer insulating film. be able to.

[Brief description of the drawings]

FIG. 1 is a process chart showing an example of a manufacturing process of a semiconductor device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Silica-based coating 3 Photosensitive resin layer 4A, 4B window 5 First conductor layer

Claims (3)

[Claims] 1. A compound of the general formula (I) (Wherein, R ¹ represents an alkyl group, aryl group or fluoroalkyl group having 1 to 6 carbon atoms, R ² represents an alkylene group or an aryl group, X represents a halogen or an alkoxy group, and n represents 0 to 2 A coating liquid for forming a silica-based film formed by hydrolytic condensation polymerization of a silane compound represented by the following formula: 2. A silica-based coating obtained by applying the coating solution for forming a silica-based coating according to claim 1 on a substrate, drying at 50 to 250 ° C., and then heating and curing at 200 to 600 ° C. in a nitrogen atmosphere. 3. A semiconductor device on which the silica-based coating according to claim 3 is formed.