JP2001098224A - Silica-based film, method of forming silica-based film, and electronic component having silica-based film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silica-based film applicable as a layer insulating film, that exhibits sufficient operating performance even in semiconductor elements whose design rule is finer than 0.15 μm, a method of forming a silica-based film that can produce easily in a high yield a silica-based film applicable as a layer insulating film for semiconductor devices such as LSI, etc., and multilayer interconnection boards, that exhibits sufficient operating performance even in semiconductor elements whose design rule is finer than 0.15 μm, and an electronic component for semiconductor devices such as LSI, etc., and multilayer interconnection boards, that has the above-described silica-based film, causes less delay of signals, and is highly graded and reliable. SOLUTION: A silica-based film having a film density of 1.5 (g/cm3) or less, a method of forming a silica-based film having a film density of 1.5 (g/cm3) or less, which method comprises coating a base material with a composition formed by dissolving a void-forming material (a) and a siloxane oligomer (b) uniformly in an organic solvent (c) to form a composite film in which the void-forming material and the siloxane oligomer are uniformly compatibilized, and carrying out the condensation reaction of the oligomer and the removal of the void-forming material, and an electronic component having the above silica-based film are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silica-based coating, a method for forming a silica-based coating, and an electronic component having a silica-based coating. More specifically, the present invention relates to a silica-based coating useful as an interlayer insulating film for a semiconductor element, a method for forming a silica-based coating, a semiconductor device having the silica-based coating, and an electronic component such as a multilayer wiring board.

[0002]

2. Description of the Related Art Along with the miniaturization of wiring due to the high integration of LSIs, an increase in signal delay time due to an increase in capacitance between wirings has become a problem. Conventionally, a SiO ₂ film formed by a CVD method with a relative dielectric constant of about 4.2 has been used as an interlayer insulating film. However, in order to reduce the capacitance between device wirings and improve the operation speed of the LSI, a lower dielectric constant is used. There is a need for a suitable film. As silica-based coatings, SiOF films with a relative dielectric constant of about 3.5 (CVD method), organic SOGs (Spin On Glass) with a relative dielectric constant of 2.5 to 3.0, organic polymers, etc. are currently in the stage of practical use. coming. On the other hand, fluororesins, porous films, and the like have been proposed for materials having a relative dielectric constant of 2.5 or less which will be required in the future, but materials having sufficient characteristics as interlayer insulating films of LSIs have been developed. There is no present.

[0003] Fluororesins are expected as low dielectric constant materials because they have a relative dielectric constant of about 2, but Tg
Is not more than 300 ° C., it is difficult to apply it to the interlayer insulating film of the LSI as it is. As a method for solving this problem, there has been proposed a composite film of a fluororesin and polysiloxane as disclosed in JP-A-9-144420. With this method, it is possible to obtain an insulating film having a relative dielectric constant of 2.5 or less, but the thermal decomposition onset temperature of the fluororesin is 400
Since the temperature is below ℃, there is a problem that there is no sufficient margin even if the process temperature of the LSI is lowered in the future.

[0004] Porous films are attracting attention as a technology capable of achieving a dielectric constant of 2.5 or less. Examples of the method for forming the porous film include a method of applying an organic polysiloxane-based coating solution containing an organic polymer such as polystyrene or polyethylene as disclosed in JP-B-6-12790 and heat-treating the same. A method for dispersing polymer particles in a polysiloxane precursor has been proposed as disclosed in the gazette. However, these methods disperse polymer particles in a polysiloxane film to form a porous film, and then remove the polymer particles by heating, so that the pore size of the obtained porous film is reduced. 0.
It is difficult to control the thickness to 1 μm or less. In a future miniaturized LSI, the wiring width is expected to be about 0.1 to 0.5 μm. Therefore, a porous film having holes having a size of 0.1 μm or more cannot be used as an interlayer insulating film.

In order to solve this problem, Japanese Patent Application Laid-Open Nos. 10-158012 and 11-217458 disclose a method of forming a porous film from a composition in which an organic polymer and polysiloxane are both dissolved in a solvent. ing.
However, the method disclosed in Japanese Patent Application Laid-Open No. H10-158012 requires a step of applying a solution of an organic polymer and a polysiloxane to a base material and then gelling at a low temperature using a base catalyst. There is a problem that the number increases and it is difficult to control the film quality. Also, JP-A-11-21745
In the method disclosed in Japanese Patent Publication No. 8 (1999), a fluororesin having high heat resistance is used as an organic polymer, and a long-time heat treatment at a high temperature (about 450 ° C.) is required to completely decompose the organic polymer. Becomes

When a conventionally used Al wiring is used as a wiring material, a processing temperature of 450 ° C. is within an allowable range, but a long-time heat treatment lowers productivity. Recently, Cu has begun to be applied as a wiring material. However, when Cu wiring is used, the permissible processing temperature is reduced (about 400 ° C.), so that this method is difficult to apply. After all, if the relative dielectric constant is 2.5 or less,
At present, a method of forming a low dielectric constant film that can be formed to a small degree and that can be applied as a semiconductor device such as an LSI having fine wiring or an interlayer insulating film of a multilayer wiring board has not been found. Therefore, a silica-based coating having a low dielectric constant, which is necessary for obtaining sufficient operation performance in a semiconductor device having a design rule finer than 0.15 μm, has not yet been obtained.

[0007]

According to the first aspect of the present invention, there is provided a silica-based film applicable as an interlayer insulating film capable of exhibiting sufficient operation performance even in a semiconductor device having a design rule finer than 0.15 μm. To provide. The invention according to claims 2 to 11 is a silica applicable as an interlayer insulating film of a semiconductor device such as an LSI or a multilayer wiring board capable of exhibiting sufficient operation performance even in a semiconductor element having a design rule finer than 0.15 μm. An object of the present invention is to provide a method for forming a silica-based coating, which can easily obtain a coating with good yield. The invention according to claim 12 is
An object of the present invention is to provide a semiconductor device such as an LSI having high signal quality and a high reliability, which has the above-mentioned silica-based coating and has a small signal delay, and an electronic component such as a multilayer wiring board.

[0008]

The present invention relates to a silica-based coating having a film density of 1.5 (g / cm ³ ) or less. Further, the present invention provides a method in which (a) a void-forming material and (b) a composition obtained by uniformly dissolving a siloxane oligomer in an (c) organic solvent are applied to a substrate, and the void-forming material and the siloxane oligomer are uniformly dispersed. The present invention relates to a method for forming a silica-based film having a film density of 1.5 (g / cm ³ ) or less, which comprises performing a condensation reaction of a siloxane oligomer and removing a void-forming material after forming a dissolved composite film. .

Further, the present invention provides a first heating step of forming a composite film in which a void-forming material and a siloxane oligomer are uniformly mixed and then crosslinking the siloxane oligomer in a state where the void-forming material remains, The present invention relates to the above-mentioned method for forming a silica-based film, wherein a second heating step of removing a material is performed. In the present invention, the temperature of the first heating step is 80 to 350 ° C., and the temperature of the second heating step is 350 ° C.
The present invention relates to a method for forming the above-mentioned silica-based coating film at a temperature of from 500 to 500 ° C. In addition, the present invention provides the method wherein (c) the organic solvent comprises (c1)
The present invention relates to the above-mentioned method for forming a silica-based coating, comprising an organic solvent in which both (a) and (b) are dissolved.

[0010] The present invention also relates to the method for forming a silica-based coating, wherein the siloxane oligomer (b) is a compound having a non-hydrolyzable organic group. Also, the present invention provides a method for producing a siloxane oligomer according to the following general formula (I):

Embedded image (Wherein, R ¹ and R ² represent the same or different non-hydrolyzable groups, R ³ represents an alkyl group having 1 to 6 carbon atoms, m
And n are 0-3 selected so as to satisfy 0 ≦ m + n ≦ 3.
Which is an integer of the formula (1).

[0011] The present invention also provides (a) a method in which the pore-forming material is subjected to thermogravimetric analysis at a temperature rising rate of 20 ° C / min from 30 ° C or less in an air stream at 250 ° C with respect to a weight of 150 ° C. The present invention relates to the method for forming a silica-based coating, wherein the polymer has a weight loss of less than 5%. Further, the present invention provides (a)
The gap forming material is heated from 30 ° C. or lower to a heating rate of 2
The present invention relates to the above-mentioned method for forming a silica-based coating, which is a polymer whose weight loss at 400 ° C. with respect to the weight at 150 ° C. when performing thermogravimetric analysis at 0 ° C./min is 80% or more.
The present invention also relates to the method for forming a silica-based coating, wherein the (a) void-forming material is a polymer containing no fluorine. The present invention also relates to the method for forming a silica-based coating, wherein (a) the void-forming material is a methacrylic polymer or an acrylic polymer. Further, the present invention relates to an electronic component having the silica-based coating.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The silica-based coating of the present invention must have a density of 1.5 (g / cm ³ ) or less, more preferably 1.3 (g / cm ³ ) or less. And 1.2 (g
/ cm ³ ) or less. The lower limit of the density is 0.5 (g / cm
³ ) about. If the density of the film exceeds 1.5 (g / cm ³ ), the dielectric constant becomes high, and sufficient operation performance cannot be exhibited in a semiconductor device having a design rule finer than 0.15 μm. When the density of the film is less than 0.5 (g / cm ³ ), formation tends to be difficult and mechanical strength tends to be poor. The density can be determined from the weight of the membrane and the volume of the membrane.

The dielectric constant of the silica-based coating is preferably 2.5 or less. In addition, the degassing amount of the silica-based coating is 1 × 10 ²¹ molecules / mol from the viewpoint of applicability to a semiconductor device.
cm ³ or less, and the leakage current characteristic is 5 × 10 ⁻⁹ A / cm ²
The following is preferred. Further, the silica-based coating of the present invention preferably contains Si—O and Si—CH ₃ as a structure.

The silica-based coating having a density of 1.5 (g / cm ³ ) or less has, for example, a composition in which (a) a void-forming material and (b) a siloxane oligomer are uniformly dissolved in (c) an organic solvent. The product can be formed by applying a substance to a substrate, forming a composite film in which the void-forming material and the siloxane oligomer are uniformly dissolved, and then performing a condensation reaction of the siloxane oligomer and removing the void-forming material. By adjusting the composition of the composition, the heating conditions, and the like, the density of the silica-based coating obtained in the range of 1.5 (g / cm ³ ) or less can be easily adjusted.

The (a) void-forming material in the present invention is not particularly limited as long as it has a function of forming voids in the silica-based coating finally obtained, and the material disappears by irradiation with electromagnetic waves or the like. Materials that are eluted and decomposed by a chemical solution, materials that are decomposed by heat, and the like are included. From the viewpoint of handling properties and workability, materials which decompose by heat, among them, thermally decomposable polymers are preferable.For example, acrylic polymers, methacrylic polymers, polyester polymers, polyether polymers, vinyl polymers, polyimide polymers, Examples thereof include vinylidene fluoride-based polymers, fluorine-containing vinyl-based polymers, and solvent-soluble perfluoropolymers. These are used alone or in combination of two or more.

(A) The decomposition temperature of the void-forming material can be confirmed using thermogravimetric analysis. The decomposition temperature can be confirmed by performing (a) thermogravimetric analysis of the void-forming material using the following apparatus and conditions. Apparatus: TG-DTA6200 (manufactured by Seiko Denshi) Temperature rising start temperature: 30 ° C. or less Temperature rising rate: 20 ° C./min Sample amount: 10 mg Atmosphere: Air 200 ml / min (a) The standard before the decomposition of the void forming material The weight used was the weight at 150 ° C. during the temperature rise. Weight loss at 150 ° C or lower occurs due to removal of adsorbed moisture and the like.
(A) It was caused by factors other than the decomposition of the void forming material.

(A) a weight loss at 250 ° C. of 5% or more
Examples of the void-forming material include polyether polymers such as tetramethylene oxide and polyethylene glycol. Examples of the (a) void-forming material whose weight loss at 250 ° C. is less than 5% include vinyl ester-based polymers such as polyvinyl acetate, methacrylate-based polymers such as polymethyl methacrylate, and polymethyl acrylate. Allylic acid ester-based polymers, polyvinyl alcohol, polyethylene imine, fluororesins and the like.

If the weight loss at 250 ° C. is less than 5%,
Examples of the (a) void-forming material whose weight loss at 0 ° C. is 80% or more include methacrylate-based polymers such as polymethyl methacrylate, acrylate-based polymers such as polymethyl acrylate, and polyethyleneimine. Among them, polymethyl methacrylate, methacrylate polymer such as polymethyl acrylate, acrylate polymer,
The weight loss at 250 ° C. is less than 2%, and the weight loss at 400 ° C. is 90% or more, which is particularly excellent as the (a) void-forming material used in the composition of the present invention.

Since a fluororesin has a heat resistance of about 400 ° C., a heating temperature of about 400 ° C. requires long-time heating to remove the polymer, and the practicability tends to be poor. Therefore, (a) a polymer containing no fluorine is preferable as the void forming material.

As the polysiloxane oligomer (b) in the present invention, for example, the following general formula (I)

Embedded image (Wherein, R ¹ and R ² represent the same or different non-hydrolyzable groups, R ³ represents an alkyl group having 1 to 6 carbon atoms, m
And n are 0-3 selected so as to satisfy 0 ≦ m + n ≦ 3.
And a hydrolyzed condensate of an alkoxysilane represented by the formula: The hydrolyzed condensate may be partially hydrolyzed and condensed, or may be entirely hydrolyzed and condensed.

The above non-hydrolyzable group is preferably a non-hydrolyzable group having 1 to 14 carbon atoms from the viewpoint of availability. Non-hydrolyzable groups include γ-glycidoxypropyl group, γ
An organic group having a reactive group such as -aminopropyl group, aminophenyl group, N-phenyl-γ-aminopropyl group,
Alkyl group such as methyl group, ethyl group, propyl group and butyl group, alkenyl group such as vinyl group, aryl group such as phenyl group and tolyl group, trifluoromethyl group, trifluoropropyl group, pentafluorobutyl group and nonafluoro group And a fluorinated alkyl group such as a hexyl group, a tridecafluorooctyl group, a heptadecafluorodecyl group, and a heptadecafluoroundecyl group. Among the non-hydrolyzable groups, an alkyl group and an aryl group are particularly preferable. Since the alkyl group and the aryl group have high heat resistance and are hydrophobic, a silica-based film having high heat resistance and low moisture absorption can be obtained by using them.

In the present invention, the hydrolyzed condensate includes a hydrolyzed condensate of general formula (I) where m = n = 0, a hydrolytic condensation of m + n = 1, a hydrolytic condensation of m + n = 2 and a m + n = 3
Or a combination of two or more selected from the group consisting of hydrolytic condensation of However, naturally m
Since the alkoxysilanes with + n = 3 have only one hydrolyzable group in the molecule and cannot form a hydrolyzed condensate by themselves, the alkoxysilanes with m + n = 3 are For the purpose of suppressing an excessive reaction of a hydrolysis-condensation product of alkoxysilanes in a solution, m = n =
0 alkoxysilanes, m + n = 1 alkoxysilanes or m + n = 2 alkoxysilanes. Alkoxysilanes with m + n = 3 are preferably 10 mol% or less based on all alkoxysilanes.

Further, m = n = having no non-hydrolyzable group
By appropriately adding 0 alkoxysilanes, the mechanical strength of the resulting silica-based coating can be improved. However, m =
When the ratio of the alkoxysilanes with n = 0 increases, the dielectric constant of the obtained film increases, and the moisture absorption also increases. Therefore,
It is preferable that the amount of the alkoxysilanes in which m = n = 0 is determined from the balance between the mechanical strength of the film, the dielectric constant, and the moisture absorption. A preferable addition amount is 0.1 to 0.7 mol of alkoxysilanes with m = n = 0 based on 1 mol of the alkoxysilane having a non-hydrolyzable group.

Specific examples of these alkoxysilanes are shown below. Tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane and tetrapropoxysilane, monoalkyl trialkoxysilanes such as methyltrimethoxysilane and methyltriethoxysilane, and monoaryltrialkanes such as phenyltrimethoxysilane and phenyltriethoxysilane Alkoxysilanes, vinyltrimethoxysilane, monoalkenyl trialkoxysilanes such as vinyltriethoxysilane, trifluoromethyltrimethoxysilane, trifluoropropyltrimethoxysilane, pentafluorobutyltrimethoxysilane,
Nonafluorohexyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, heptadecafluorodecylmethyldimethoxysilane, heptadecafluoroundecyltrimethoxysilane, (4-perfluorobutylphenyl) trimethoxysilane , Fluorine-containing alkoxysilanes such as (4-perfluorohexylphenyl) trimethoxysilane, (4-perfluorooctylphenyl) trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, etc. Epoxysilanes, aliphatic aminosilanes such as γ-aminopropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, aminophenyltrimethoxysilane, Roh phenyltriethoxysilane,
And aromatic ring-containing aminosilanes such as N-phenyl-γ-aminopropyltrimethoxysilane. These are used alone or in combination of two or more.

The condensation reaction of the alkoxysilanes can be carried out by a conventional method.
There is a method in which water is added to cause a hydrolytic condensation reaction 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 weight-average molecular weight of the hydrolyzed condensate (value determined by gel permeation chromatography (GPC) and converted to standard polystyrene) is in the range of 500 to 10000, which indicates compatibility with the pore-forming material and solubility in the solvent. It is preferable from the viewpoint of. Then, if necessary, water 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.

The method for preparing the mixed solution of (a) the void-forming material and (b) the siloxane oligomer is not particularly limited as long as a uniform solution can be prepared as a result, and the following methods (1) to (3) are exemplified. You. (1) A method in which (a) a solution of the void-forming material and (b) a solution of the siloxane oligomer are separately prepared in advance, and both are mixed. In this case, the solution of the (b) siloxane oligomer was directly prepared in a solvent compatible with the solution of the void-forming material, and the solution was synthesized in a solvent incompatible with the solution of the void-forming material. Later, a solution of a compatible solvent may be obtained by a known solvent replacement method. The latter is used, for example, when the hydrolysis-condensation reaction of alkoxysilanes does not proceed sufficiently in a solvent compatible with the solution of the pore-forming material (a), or when it is difficult to control the degree of polymerization of the condensate. (2) A method in which alkoxysilanes are dissolved in a solution of the pore-forming material (a) prepared in advance, and a hydrolytic condensation reaction is performed in the solution. (3) A method in which a (b) siloxane oligomer solution is prepared in advance, and (a) a void-forming material is added thereto and dissolved.

The ratio of the amount of the (a) void-forming material to the amount of the (b) siloxane oligomer used can be set to an arbitrary ratio according to the purpose. ) The siloxane oligomer is preferably added in an amount of 10 to 1000 parts by weight, more preferably 60 to 450 parts by weight. However, the weight of the siloxane oligomer (b) is determined by the fact that all hydrolyzable groups are condensed and Si
This is a value calculated assuming that a bond of —O—Si is formed. (B) If the proportion of the siloxane oligomer is too small, the mechanical strength of the resulting silica-based coating tends to decrease, and if it is too large, the relative dielectric constant of the resulting film tends to increase.

The (a) void-forming material may have a functional group, but it is not preferable that the functional group cross-links with the (b) hydrolyzable group of the siloxane oligomer and the silanol group generated by hydrolysis. When the (a) void-forming material and the (b) siloxane oligomer crosslink, a silanol group is generated after the (a) void-forming material is removed by heating, and the low dielectric property and low hygroscopicity of the film are impaired. In the case where the functional group of the (a) void-forming material does not undergo a cross-linking reaction with the (b) hydrolyzable group of the siloxane oligomer and the silanol group generated by the hydrolysis, and only interaction due to the polarity of the functional group occurs, The compatibility between a) the void-forming material and (b) the siloxane oligomer is improved, and a more uniform silica-based coating is obtained.

In the present invention, (c) the organic solvent includes
For example, alcohols such as methanol, ethanol propanol and butanol, CF ₃ CH ₂ OH, CF ₃ CF ₂ C
H ₂ OH, fluorinated alcohols such as CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ OH, acetates such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate, lactones such as γ-butyrolactone, ethylene glycol monomethyl Examples thereof include glycol acetate solvents such as acetate and ethylene glycol diacetate, amide solvents such as N-methyl-2-pyrrolidone, and glycol ether solvents. These are used alone or in combination of two or more. Among these (c) organic solvents, it is preferable to use an organic solvent (c1) that dissolves both (a) the void-forming material and (b) the siloxane oligomer.

(C) The amount of the organic solvent to be used may be appropriately selected from the viewpoint of a desired solution viscosity or a coating film thickness. For example, a coating film having a thickness of 0.1 to 5 μm is spin-coated. When it is intended to obtain the above, it is preferable to use an amount such that the solid content concentration of the composition is 1 to 20% by weight.

The silica-based coating is formed, for example, by applying the composition to a substrate, forming a composite film in which (a) a void-forming material and (b) a siloxane oligomer are uniformly dissolved, and then heating the composite film by (H). b) Condensation reaction of siloxane oligomer and (a)
It can be performed by a method of removing the void forming material. In this method, it is important that in the heating step after the application, (a) condensation of the siloxane oligomer occurs in a state where the void forming material is present in the film, and a polysiloxane network is formed. In the case where the decomposition of the (a) void-forming material starts before the formation of the polysiloxane network, (a) the film may shrink due to the decomposition of the void-forming material, and the low dielectric property of the resulting film may be impaired. There is.

In order to obtain a silica-based film having high heat resistance and low moisture absorption, it is preferable to use (b) a siloxane oligomer having a non-hydrolyzable group. When the (b) siloxane oligomer is heated without using a basic catalyst, condensation starts at 150 ° C. or higher. It is at 250 ° C. or higher that the condensation proceeds and a polysiloxane network is formed to substantially determine the structure of the film. Accordingly, in order to obtain a silica-based coating having high heat resistance and low moisture absorption in the present invention, the (a) void-forming material preferably has a decomposition initiation temperature of 150 ° C or higher, more preferably 250 ° C or higher. From this point of view, (a) the air gap forming material is heated at a rate of 20 ° C./min from 30 ° C. or less under an air stream.
When a thermogravimetric analysis was performed at 25 ° C., 25
It is preferable that the polymer has a weight loss of less than 5% at 0 ° C., and that the weight loss at 400 ° C. relative to the weight of 150 ° C. is 80% or more.

In order to obtain a silica-based coating by the method of the present invention, it is preferable to sufficiently remove (a) the void-forming material. (A) If the removal of the void-forming material is incomplete, the low dielectric property of the resulting film is likely to be impaired.

When the present invention is applied to the formation of an interlayer insulating film of an LSI, the applied heating temperature differs depending on the wiring material. The heating temperature when using the conventional Al wiring is 400 ° C.
The heating temperature when using Cu wiring is expected to be about 380 to 430 ° C. in the future. Therefore, when the present invention is applied to an LSI using Cu wiring, it is preferable that (a) the void forming material be sufficiently removed at 400 ° C. or lower. Also, when an Al wiring is used, it is preferable that the (a) void-forming material be removed at a temperature of 400 ° C. or lower because a change in the dielectric constant due to the heating temperature is reduced.

The method of applying the composition of the present invention includes spin coating, dipping, potting, die coating, spray coating, etc., and is appropriately selected from the shape of the article to be coated, the required film thickness, and the like. do it. When the composition of the present invention is applied to a semiconductor element interlayer insulating film, a spin coating method is preferred from the viewpoint of uniformity of in-plane distribution of film thickness. When applied to the multilayer wiring board interlayer insulation film,
A die coating method is preferable as a method for achieving a higher liquid yield together with the spin coating method.

In order to form a coating film, (c) to volatilize an organic solvent and (a) to condense a siloxane oligomer in a state where a void forming material is present in the film, and (b) to condense a siloxane oligomer. Preferably, baking is performed. The baking conditions may be appropriately selected depending on the thickness of the coating film, etc., and baking is performed at 80 to 200 ° C. for drying the solvent and at 200 to 350 ° C. for the condensation reaction of the (b) siloxane oligomer. Is preferred. It is preferable to use a hot plate for baking.

(B) In order to sufficiently condense the siloxane oligomer so that unreacted alkoxy groups or silanol groups do not remain and (a) sufficiently remove the void-forming material, final curing at 350 to 500 ° C. Is preferred. Unreacted alkoxy groups or silanol groups themselves cause an increase in the dielectric constant of the coating film, and furthermore, can cause water absorption sites to increase the dielectric constant of the coating film. Desirably does not remain. The final curing is preferably performed using a hot plate or a furnace.

By applying the silica-based coating formed from the composition as an interlayer insulating film of a semiconductor device and a multilayer wiring board, excellent electrical characteristics such as a low dielectric constant and a high dielectric strength, a reduction in signal propagation delay time, and the like can be obtained. High performance can be achieved. The present invention is also applicable to a case where the process temperature is lowered by using Cu wiring for a semiconductor element.

The semiconductor element according to the present invention includes diodes, transistors, compound semiconductors, individual semiconductors such as thermistors, varistors, thyristors, DRAMs (Dynamic Random Access Memory), SRAMs (Static Random Access Memory), EPROM
(Erasable programmable read only
Memory), mask ROM (mask read only)
Memory), EEPROM (electrically erasable programmable read only memory), storage elements such as flash memory, microprocessors,
Theoretical circuit elements such as DSPs and ASICs, integrated circuit elements such as compound semiconductors represented by MMICs (monolithic microwave integrated circuits), hybrid integrated circuits (hybrid ICs), photoelectric conversion elements such as light-emitting diodes, charge-coupled devices, etc. Means

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, it is possible to attain high performance such as reduction of signal propagation delay time and high reliability as described above.

[0041]

The present invention will be described below with reference to examples.

Example 1 140 g of CH ₃ Si (OCH ₃ ) ₃ was dissolved in 130 g of γ-butyrolactone, and a mixed solution of 60 g of water and 0.5 g of nitric acid was added dropwise over 1 hour, followed by further reaction at room temperature for 24 hours. I let it. A solution prepared by mixing 400 g of a 10% by weight solution of polymethyl methacrylate with γ-butyrolactone at room temperature for 24 hours was used as a coating solution for forming a silica-based film. This coating solution was applied on a 6-inch silicon wafer at 2,000 min ^-1 using a spinner, dried on a hot plate controlled at 150 ° C. and 250 ° C. for 1 minute, and then placed in an electric furnace at 400 ° C. for 1 hour in nitrogen. Upon firing, a colorless, transparent and crack-free coating was obtained. The thickness of the film was measured and found to be 0.55 μm.

The density determined from the weight of the film and the volume of the film was 1.3 (g / cm ³ ). An aluminum film of 1 μm is formed on this film by sputtering, and the dielectric constant of the sample is set to L.
It was 2.1 when measured at a frequency of 10 kHz using an F impedance meter. Further, the degassing amount of the coating is measured by a temperature desorption gas analyzer: TDS (EMD-
It was 3 × 10 ¹⁹ molecules / cm ^{3 as} determined by 1000 K), and the leak current of the coating was measured using a mercury probe IV measuring device (SSM495, manufactured by SSM, Japan). × 10 ⁻¹⁰ A / cm ² .

Comparative Example 1 140 g of CH ₃ Si (OCH ₃ ) ₃ was dissolved in 300 g of γ-butyrolactone, and a mixture of 60 g of water and 0.5 g of nitric acid was added dropwise over 1 hour, followed by further reaction at room temperature for 24 hours. This was used as a coating solution for forming a silica-based film. This coating solution was applied on a 6-inch silicon wafer at 2,000 min ^-1 using a spinner, dried on a hot plate controlled at 150 ° C. and 250 ° C. for 1 minute, and then placed in an electric furnace at 400 ° C. for 1 hour in nitrogen. Upon firing, a colorless, transparent and crack-free coating was obtained. The thickness of the film was measured and found to be 0.50 μm. The density determined from the weight of the film and the volume of the film was 1.7 (g / cm ³ ). An aluminum film 1 μm is formed on the film by a sputtering method,
The dielectric constant of this sample was measured at a frequency of 10 kHz using an LF impedance meter, and was 2.8.

[0045]

According to the first aspect of the present invention, there is provided a silica-based film applicable as an interlayer insulating film capable of exhibiting sufficient operation performance even in a semiconductor device having a design rule finer than 0.15 μm. Things. The method for forming a silica-based coating according to claim 2, wherein the interlayer insulating film of a semiconductor device such as an LSI or a multilayer wiring board capable of exhibiting sufficient operation performance even in a semiconductor element having a design rule finer than 0.15 μm. It is possible to easily obtain a silica-based coating which can be applied as a high yield.
13. An electronic component according to claim 12, wherein said LSI-based coating has a low signal delay, a high quality and a high reliability.
And a multilayer wiring board.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C08L 83/04 C08L 83/04 5F033 101/00 101/00 5F058 C09D 133/06 C09D 133/06 183/02 183/02 183/06 183/06 H01L 21/312 H01L 21/312 C 21/316 21/316 G 21/768 21/90 SQ (72) Inventor Shigeru Nobe 4-3-1, Higashicho, Hitachi City, Hitachi, Ibaraki Hitachi (72) Inventor Takenori Narita 4-3-1-1, Higashicho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd.Yamazaki Office (72) Inventor Nobuko Terada 4--13 Higashimachi, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. Yamazaki Office (72) Inventor Hiroyuki Morishima 4-3-1 Higashicho, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Office F-term (reference) 4D075 BB21X BB93X CA23 CA48 DA06 DB14 DC22 EB22 EB42 EB45 EC30 4F074 AA38 AA47 AA65 AA74 AA76 AA90 CB06 CB17 CC12Y CC32Y DA02 DA47 4J002 BD14X BG03X CF00X CH 00X CM04X CP03W 4J035 CA01K LA03 LB20 4J038 CG142 DL021 DL031 KA02 KA06 MA07 MA10 MA12 NA21 PA19 PB09 5F033 HH08 HH11 QQ74 RR23 RR29 SS22 VV16 VV17 WW00 BD03A02A03A03

Claims (12)

[Claims] 1. A silica-based film having a film density of 1.5 (g / cm ³ ) or less. 2. A composition comprising (a) a void-forming material and (b) a siloxane oligomer uniformly dissolved in (c) an organic solvent is applied to a substrate, and the void-forming material and the siloxane oligomer are uniformly compatible. A method for forming a silica-based film having a film density of 1.5 (g / cm ³ ) or less, comprising performing a condensation reaction of a siloxane oligomer and removing a void-forming material after forming the composite film. 3. A first heating step of forming a composite film in which the void-forming material and the siloxane oligomer are uniformly dissolved and then crosslinking the siloxane oligomer in a state where the void-forming material remains, and removing the void-forming material. 3. The method according to claim 2, wherein a second heating step is performed. 4. The temperature of the first heating step is 80 to 350 ° C.
The method according to claim 3, wherein the temperature of the second heating step is 350 to 500C. 5. The method according to claim 2, wherein (c) the organic solvent comprises an organic solvent in which both (c1) (a) and (b) are soluble. 6. The compound according to claim 2, wherein (b) the siloxane oligomer is a compound having a non-hydrolyzable organic group.
Or the method for forming a silica-based coating according to 5. (B) the siloxane oligomer is represented by the following general formula (I): (Wherein, R ¹ and R ² represent the same or different non-hydrolyzable groups, R ³ represents an alkyl group having 1 to 6 carbon atoms, m
And n are 0-3 selected so as to satisfy 0 ≦ m + n ≦ 3.
7. The method for forming a silica-based coating according to claim 2, which is a hydrolyzed condensate of an alkoxysilane represented by the following formula: 8. The method according to claim 8, wherein (a) the gap-forming material is placed in an air stream at 30 ° C.
A polymer which has a weight loss of less than 5% at 250 ° C. with respect to the weight of 150 ° C. when thermogravimetric analysis is performed at a temperature rising rate of 20 ° C./min from a temperature of not more than 5 ° C.
9. The method for forming a silica-based coating according to 6, 7, or 8. 9. The method according to claim 9, wherein (a) the gap-forming material is placed under an air stream.
A polymer whose weight loss at 400 ° C. with respect to the weight at 150 ° C. is 80% or more when subjected to thermogravimetric analysis at a temperature rising rate of 20 ° C./min from below 100 ° C.
9. The method for forming a silica-based coating according to 5, 6, 7, or 8. 10. The method according to claim 2, wherein (a) the void-forming material is a polymer containing no fluorine. 11. The method according to claim 2, wherein (a) the void-forming material is a methacrylic polymer or an acrylic polymer.
The method for forming a silica-based coating according to 4, 5, 6, 7, 8, 9, or 10. 12. An electronic component having the silica-based coating according to claim 1.