JPH05315319A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To remove void, a pinhole, or the like by a method wherein ion density contained in applying liquid for forming a film is lowered so as to be 1.0 millimol/l or less. CONSTITUTION:This semiconductor device contains a substance obtained by reacting silica sol obtained by making hydrolysis and polycondensation for alkoxy silane with this alkoxy silane or its partial hydrolytic substance and has a silica group insulating film formed with applying liquid for forming a film which has ion density of 1.0millimol/l or less. Also, treatment by positive ion exchange resin and treatment by negative ion exchange resin are performed to obtain the applying liquid for forming the film of which the ion density is made to be 1.0millimol/l or less. Thus, it is possible to form a minute silica insulating film having excellent close adhesion, mechanical strength, chemical resistance, wet resistance, and insulation, and having low specific dielectric constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method for manufacturing the same, and more specifically, it is dense and has no defects such as cracks, voids, and pinholes, and has high adhesion to a substrate, mechanical strength, and chemical resistance. Of a silica-based insulating film having excellent properties, moisture resistance, insulation properties, a small relative dielectric constant and excellent flatness, and a silica-based insulating film having such excellent properties on a substrate. The present invention relates to a method for manufacturing a semiconductor device formed on a substrate.

[0002]

BACKGROUND OF THE INVENTION An insulating film for a semiconductor device is provided between polysilicon and an aluminum wiring layer or between these layers in order to insulate the aluminum wiring layer from each other. It is provided on the surface of the semiconductor device to protect the semiconductor device.

As a method of forming such an insulating film, a vapor phase growth method such as a CVD method is usually carried out. In addition, an organic silicon compound such as silanol is dissolved or dispersed in alcohol to apply a coating solution to a substrate, and the resulting coating film is heated to a temperature of about 400 to 500 ° C. to cure the resulting silica-based insulation. Methods of forming a film are also known.

However, when the silica-based insulating film is formed by such a conventional coating method, the shrinkage rate of the film during film formation is large. Therefore, when the film is thick, cracks are generated in the silica-based insulating film. There was a problem that it became easier to do.

In order to solve these problems, the inventors of the present invention have disclosed the general formula R _n S in Japanese Patent Laid-Open No. 10418/1992.
i (OR ') _4-n (In the formula, R and R'represent an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, and n is 0.
Is an integer of ~ 3. From a coating solution for forming a film containing a reaction product of a silica sol (A) obtained by hydrolytic polycondensation of an alkoxysilane represented by the formula (4) and an alkoxysilane represented by the above formula or a partial hydrolyzate (B) thereof. A semiconductor device having a formed silica-based insulating film is proposed.

A silica-based insulating film formed from such a coating liquid for forming a film is excellent in denseness and, at the same time, does not generate cracks. Therefore, according to the method proposed by the present inventors, a semiconductor device having a silica insulating film having excellent mechanical strength, chemical resistance, moisture resistance, and insulation properties, a small relative dielectric constant, and excellent flatness is obtained. be able to. Further, the silica insulating film thus formed on the semiconductor base material satisfies the adhesiveness with the base material required for a normal semiconductor device.

However, in recent years, as the density of semiconductor devices has increased and the applications thereof have expanded, it has been desired to form an insulating film that is more dense and has a smaller relative dielectric constant than conventional ones.

The inventors of the present invention have made earnest studies to obtain a denser silica-based coating having a smaller relative dielectric constant than the conventional coating liquid for forming a coating as described above. As a result, the alkoxy represented by the above formula is obtained. When an alkali used as a catalyst in obtaining a silica sol by hydrolytic polycondensation of silane, or an acid or an alkali used as a catalyst in partially hydrolyzing the alkoxysilane remains as ions in the coating liquid, It has been found that due to the ions, voids, pinholes, etc. are generated in the coating film formed from the coating liquid to reduce the denseness of the coating film, or the relative dielectric constant of the coating film is increased.

As a result of further studies, the present inventors have found that
When the concentration of ions contained in the coating liquid for forming a film is lowered to 1.0 mmol / liter or less, the coating liquid for forming a film is almost free of voids and pinholes and is dense and has a relative dielectric constant. The inventors have found that a silica-based insulating film having a low rate can be obtained, and completed the present invention.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems in the prior art as described above, and it is dense and has almost no voids, pinholes, etc.
A semiconductor device in which a silica-based insulating film having excellent mechanical strength, chemical resistance, moisture resistance, insulation, etc., and a low relative dielectric constant is formed, and a silica-based insulating film having such excellent properties are formed. Another object of the present invention is to provide a method for manufacturing a semiconductor device.

[0011]

SUMMARY OF THE INVENTION A semiconductor device according to the present invention has the general formula R _n
Alkoxysilane represented by Si (OR ') _4-n (wherein R and R'represent an alkyl group, an aryl group or a vinyl group having 1 to 8 carbon atoms, and n is an integer of 0 to 3). Containing a reaction product of a silica sol (A) obtained by hydrolytic polycondensation of the above with an alkoxysilane represented by the above formula or a partial hydrolyzate thereof (B), and having an ion concentration of 1.0 mmol / liter or less. It is characterized by having a silica-based insulating film formed from a coating film forming coating liquid.

Further, in such a semiconductor device, a cation is added to at least one of the liquid containing the silica sol (A), the alkoxysilane represented by the above formula or its partial hydrolyzate (B) and the coating liquid for forming a film. The ion concentration in the coating liquid for forming a film obtained by performing the treatment with the exchange resin and the treatment with the anion exchange resin is 1.0 mmol /
It is manufactured by including a step of applying a coating solution for forming a coating film having a volume of 1 liter or less on a semiconductor substrate and curing the obtained coating film by heating to form a silica-based insulating film.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The semiconductor device and the method of manufacturing the same according to the present invention will be specifically described below. In a semiconductor device, layers such as a polysilicon layer and an aluminum wiring layer are usually laminated on the substrate, and various elements such as a PN junction semiconductor and a capacitor are provided on the surface of the semiconductor device.

The semiconductor device according to the present invention is provided with various elements such as between such polysilicon and aluminum wiring layers, between layers such as aluminum wiring layers, or between PN junction semiconductors and capacitors. The surface of the semiconductor device has a specific silica-based insulating film.

In the present invention, when the above-mentioned silica-based insulating film is formed, it contains a reaction product of a specific silica sol (A) and a specific alkoxysilane or a partial hydrolyzate thereof (B), A coating solution for forming a film is used in which the ion concentration in the coating solution is 1.0 mmol / liter or less.

The silica sol (A) has the general formula R
_n Si (OR ′) _4-n (wherein R and R ′ have 1 to 8 carbon atoms)
Represents an alkyl group, an aryl group or a vinyl group of
Is an integer of 0 to 3. A silica sol obtained by hydrolyzing and polycondensing an alkoxysilane represented by the formula 1) in the presence of water, an organic solvent and an alkali catalyst is used.

Specific examples of the alkoxysilane represented by the above general formula include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraoctylsilane, methyltrimethoxysilane, methyltriethoxysilane and ethyltrisilane. Ethoxysilane, methyltriisopropoxysilane, methyltributoxysilane, octyltriethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane,
Examples thereof include dimethyldimethoxysilane, diethyldiethoxysilane, trimethylmonomethoxysilane, and triethylmonoethoxysilane.

In the present invention, these alkoxysilanes may be used alone or in combination of two or more kinds. Examples of the organic solvent include alcohols, ketones, ethers, and esters, and more specifically,
For example, alcohols such as methanol, ethanol, propanol and butanol, ethylene glycol ethers such as methyl cellosolve and ethyl cellosolve, glycols such as ethylene glycol and propylene glycol, esters such as methyl acetate, ethyl acetate and methyl lactate are used. Be done.

As the alkali catalyst, compounds showing alkalinity in an aqueous solution such as ammonia, amine, alkali metal catalyst, quaternary ammonium compound and amine coupling agent are used, and the pH of the reaction mixture is preferably 7 to 12. Is used in an amount such that it is 8-11.

The method for preparing the silica sol (A) will be described in more detail. For example, while stirring a water-alcohol mixed solvent, an alkoxysilane and an alkali catalyst such as aqueous ammonia are added to the mixed solvent. React with alkoxysilane.

At this time, water is 5 to 50 mol, preferably 5 to 1 mol per 1 mol of Si-OR groups contained in the alkoxysilane.
The amount of the alkali catalyst used is such that the above-mentioned pH is reached, for example, 0.01-1.0.
It is blended in an amount such that it is mol / SiO ₂ mol, preferably 0.05 to 0.8 mol / SiO ₂ mol.

The hydrolysis-polycondensation reaction of the alkoxysilane is usually carried out at a temperature not higher than the boiling point of the solvent used under normal pressure, preferably at a temperature 5 to 10 ° C. lower than this boiling point. It can also be carried out under pressure in a pressure vessel, and in this case, it is carried out at a temperature higher than the boiling point of the solvent under normal pressure.

When the alkoxysilane is hydrolyzed under such conditions, polycondensation of the alkoxysilane proceeds three-dimensionally, silica particles are produced, and the produced silica particles grow.

In addition, silica particles are produced in this manner.
After the growth, the heat treatment may be performed at a temperature equal to or higher than the boiling point of the solvent used for a certain period of time. By performing such heat treatment, polycondensation of alkoxysilane is further promoted, and a silica sol in which silica particles having a high density are dispersed can be obtained.

A silica sol is thus obtained,
In the present invention, the silica sol (A) is preferably a silica sol in which uniform silica particles having an average particle size of about 50 to 500 angstroms, particularly 100 to 500 angstroms are dispersed in a solvent. When the particle size is less than 50 angstroms, when a film is formed using a coating solution for forming a film obtained by using silica sol containing such silica particles as a raw material, cracks may occur on the formed film surface, Further, when the average particle size of silica particles contained in the silica sol exceeds 500 angstroms, voids frequently occur in the coating film, and a dense coating film may not be obtained.

In the present invention, it is desirable that the silica particles are contained in the silica sol in an amount of about 50% by weight or less, preferably 40% by weight or less in terms of SiO ₂ . If the content of silica particles contained in this silica sol exceeds 50% by weight, gelation tends to occur.

In the present invention, the unpurified silica sol obtained by the above method can be used as it is, but the reaction between the silica sol (A) and the alkoxysilane or its partial hydrolyzate (B) as described below is carried out. It is preferable that the solvent is previously replaced with water from a mixed solvent of water and an organic solvent by means such as ultrafiltration from silica sol in advance.

Such solvent replacement operation may be carried out before the above-mentioned heat treatment of the silica sol. In the present invention, the silica sol obtained as described above may be subjected to a deionization treatment with a cation exchange resin and an anion exchange resin.

When the semiconductor device according to the present invention is manufactured, the reaction product obtained by reacting the silica sol (A) thus obtained with the alkoxysilane or its partial hydrolyzate (B) A coating liquid for forming a film is used.

Used in the reaction with the above silica sol (A)
Alkoxysilane as a raw material for silica sol (A)
Similar to the used alkoxysilane, the general formula R_nSi (O
R ') _4-n(In the formula, R and R'are alkyl having 1 to 8 carbons.
Represents a group, an aryl group or a vinyl group, and n is 0 to 3
It is an integer. ) Alkoxysilane
Selected as a raw material for silica sol (A)
It does not have to be the same as the alkoxysilane used.

During the reaction process of the reaction between the silica sol (A) and the alkoxysilane or its partial hydrolyzate (B), the growth of silica particles in the silica sol or the formation of new silica particles does not occur, and On the surface of the contained silica particles, a bonding reaction between the silica particles and a new alkoxysilane or a partial hydrolyzate thereof (B) occurs, and as a result, a preferable coating for manufacturing the semiconductor device according to the present invention. A liquid is obtained.

As described above, a reaction product of silica sol (A) and alkoxysilane can be used in the coating liquid for forming a film used when manufacturing the semiconductor device according to the present invention. It is preferable to use a reaction product of a partial hydrolyzate of alkoxysilane. When the silica sol (A) and the partial hydrolyzate of the alkoxysilane are mixed and reacted as described above, gelation due to aggregation of the sol tends not to occur.

When the partial hydrolysis of the alkoxysilane is carried out, water, an organic solvent, an acid or an alkali catalyst is usually used. Examples of the organic solvent and the alkali catalyst include those mentioned above. As the acid catalyst, specifically, inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, organic acids such as acetic acid and oxalic acid, or compounds showing acidity in an aqueous solution such as metal soap are used.

The amount of water used for partial hydrolysis of the alkoxysilane is usually the amount of Si contained in the alkoxysilane.
0.1 to 2 mol, preferably 0.5 per mol of the OR group.
~ 2 moles. When an acid catalyst is used in the partial hydrolysis of alkoxysilane, the pH of the reaction solution is usually 0 to 6, preferably 1 to 3, and when an alkali catalyst is used. The reaction solution is used in such an amount that the pH of the reaction solution is usually 7 to 10, preferably 7 to 8.

The molecular weight of the partially hydrolyzed alkoxysilane obtained under the above conditions is about 100 to 10,000, preferably 500 to 5, in terms of polystyrene equivalent molecular weight.
000 is desirable.

The partial hydrolyzate of alkoxysilane can be obtained by the above method, but can also be obtained by the following method. 1) General formula R ¹ _n Si (OR ² ) _4-n (In the formula, R ¹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, and R ² represents an alkyl group having 1 to 4 carbon atoms. , An aryl group or a vinyl group, and n is an integer of 0 to 3.)
One or more of alkoxysilanes represented by
A method in which partial hydrolysis is carried out in the presence of an organic solvent, water and an alkali catalyst, and then the resulting partially hydrolyzed product is further partially hydrolyzed in the presence of water and an acid catalyst.
54279).

2) General formula R ¹ _n Si (OR ² ) _4-n (In the formula, R ¹ represents an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, and R ² has 1 to 4 carbon atoms. Which represents an alkyl group, an aryl group or a vinyl group, and n is an integer of 0 to 3) is partially hydrolyzed in the presence of an organic solvent, water and an acid catalyst. A method of decomposing, then contacting the obtained partial hydrolyzate with an alkali, and adding an acid to the solution thus obtained to make it acidic (JP-A-3-115379).

Examples of the organic solvent, acid catalyst and alkali catalyst used in the above method include those mentioned above. In the present invention, the liquid containing the alkoxysilane partial hydrolyzate obtained as described above may be subjected to a deionization treatment with a cation exchange resin and an anion exchange resin as in the silica sol (A). ..

In the coating liquid for forming a film used in manufacturing the semiconductor device according to the present invention, the silica sol (A) as described above and the alkoxysilane or its partial hydrolyzate (B) are mixed in the silica sol ( in terms of SiO ₂ by weight of SiO ₂ reduced weight of silica particles contained in the _a) (W a) / alkoxysilane or a partial hydrolyzate thereof _(B) (W B) is 0.1 to 10.0, preferably Is 0.25
It is preferable that they are mixed in a weight ratio such that the weight ratio becomes 4.0.

When the weight ratio (W _A / W _B ) exceeds 10.0, a coating film-forming coating containing a reaction product of such a silica sol (A) and an alkoxysilane or a partial hydrolyzate thereof (B). The coating film formed from the liquid has excellent heat resistance and moisture resistance, but when the film thickness increases, cracks tend to easily occur, while on the other hand, when the weight ratio (W _A / W _B ) is less than 0.1, The heat resistance and moisture resistance of the film tend to be poor.

The coating solution for forming a film used when manufacturing the semiconductor device according to the present invention is prepared by mixing the above-mentioned silica sol (A) with alkoxysilane or its partial hydrolyzate (B). 100 ° C or lower, preferably 80
0.5 ° C. or less, usually 0.5 to 5 hours, preferably 1
It is obtained by performing a heat treatment for 3 hours. The lower limit of this heat treatment is not particularly limited, but the lower the temperature, the longer the reaction time and the lower the productivity. On the other hand, if the temperature exceeds 100 ° C, the hydrolysis reaction of the alkoxysilane proceeds too much, which is not preferable.

Next, the coating solution for forming a film thus obtained is subjected to a deionization treatment. Examples of this deionization treatment method include a method of performing treatment with a cation exchange resin and treatment with an anion exchange resin. In the present invention, the ion concentration in the coating liquid for forming a film is adjusted to 1.0 mmol / liter or less by such a deionization treatment method. In addition, silica sol (A)
A liquid containing a partial hydrolyzate (B) of an alkoxysilane and / or a deionization treatment with a cation exchange resin and an anion exchange resin has been previously performed, and a coating liquid for film formation obtained by using these If the ion concentration is 1 mmol / liter or less, it is not necessary to perform the above-mentioned deionization treatment on the coating solution for forming a film again.

When the treatment with the cation exchange resin and the treatment with the anion exchange resin described above are performed, the cation exchange resin and the anion exchange resin may be alternately treated, or the cation exchange resin and the cation exchange resin may be used. It may be treated with a mixed resin with an anion exchange resin.

In the present invention, the ion concentration in the coating solution for forming a film is 1.0 mmol / liter or less, preferably 0.
By controlling the amount to 6 mmol / liter or less, there are almost no defects such as cracks, voids, and pinholes as compared with the conventional silica-based insulating coating, and the density is high and the adhesion, mechanical strength, chemical resistance, and moisture resistance are high. It is possible to form a silica-based insulating film having excellent insulating properties and a low relative dielectric constant on a semiconductor substrate.

This ion concentration means the total ion concentration of the cations and anions in the coating liquid, and in the present invention, the cation concentration and the anion concentration are measured as follows.

10 ml of the coating liquid for forming a film was mixed with 90 ml of purified pure water, stirred for 1 hour at room temperature, filtered, and the filtrate was recovered by passing 100 ml of purified pure water through the filtered filter material. ..

The metal ion concentration contained in this recovered filtrate is measured by the atomic absorption method, and the ammonium ion concentration and the anion concentration are measured by the ion chromatography method. The coating liquid for film formation before deionization treatment,
It contains an acid or alkali used as a catalyst when the alkoxysilane is hydrolyzed to produce the silica sol (A) and / or its partial hydrolyzate (B). Therefore, the coating solution for forming a film is usually contained. Has an ion concentration of more than 1 mmol / liter.

When these acids or alkalis are contained in the coating solution for forming a film, polycondensation of alkoxysilane further proceeds. That is, these acids or alkalis act as a catalyst for polycondensation of alkoxysilane during the film formation. For this reason, the polycondensation rate of the alkoxysilane contained in the coating solution is increased at the time of forming the coating film, and the film can be formed with the acid or alkali in the coating solution or a part of the organic solvent taken in. May proceed. Some of these acids or alkalis or organic solvents are gasified and removed when the coating formed on the substrate is heated and cured, but the traces may become voids or pinholes, For this reason, the denseness of the coating is lowered.

Even after the coating is heated and cured, if some of the above acids or alkalis or metal ions remain in the coating, they act as impurities, for example, insulative properties. The characteristics of the coating may be deteriorated or the relative dielectric constant of the coating may be increased.

On the other hand, when the coating solution for forming a film is subjected to the deionization treatment as described above, the ion concentration of the coating solution for forming a film can be reduced to 1 mmol / l or less,
When a silica insulating film is formed from a specific coating liquid for forming a film having an ion concentration of 1 mmol / l or less, the cause of voids, pinholes, etc. during the film formation is eliminated and at the same time the insulating property is improved. In addition, a silica insulating film having a low relative dielectric constant can be obtained.

The semiconductor device according to the present invention having such an excellent silica insulating film is manufactured as follows.
First, various elements such as polysilicon, an aluminum wiring layer, a PN junction semiconductor, or a capacitor provided on a semiconductor substrate with the above specific coating solution having an ion concentration of 1 mmol / liter or less in the coating solution. This coating liquid is applied onto the semiconductor substrate so that the silica coating film is covered, and the resulting coating film is heat-cured to form a silica-based insulating film. When the layers are insulated from each other by a silica-based insulating film, such as between the polysilicon and the aluminum wiring layer or between the aluminum wiring layer and the aluminum wiring layer, the silica-based insulating film formed as described above is used. A layer such as an aluminum wiring layer is further formed on the insulating film.

In forming the coating film by coating the coating liquid on the semiconductor substrate as described above, various methods such as a spray method, a spin coating method, a dipping method, a roll coating method, a screen printing method and a transfer printing method. Is adopted.

By drying and baking the coating film formed on the semiconductor substrate by such a method, a semiconductor device having a desired silica-based insulating film can be obtained. Furthermore, after the coating step, or the drying step, or during the drying step, the uncured coating film is irradiated with an electromagnetic wave having a wavelength shorter than visible light, such as ultraviolet rays, electron beams, or X-rays, or
Alternatively, the coating can be cured by heating in a gas atmosphere that accelerates the curing of the coating, for example, a gas atmosphere such as ammonia or ozone.

The film thickness of the film thus formed is
It is usually 0.05 to 2 μm, preferably 0.1 to 1 μm. The film formed on the semiconductor substrate as described above has almost no defects such as voids and pinholes,
It has excellent adhesion, chemical resistance, moisture resistance, and insulation, has a very low relative dielectric constant, and is free from cracks.

[0055]

As is apparent from the above description, according to the present invention, there are almost no defects such as cracks, voids, and pinholes, the density is high, and the adhesion, mechanical strength, and
Provided is a semiconductor device in which a silica insulating film having excellent chemical resistance, moisture resistance, and insulating properties and a low relative dielectric constant is formed.

[0056]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0057]

Example 1-Preparation of silica sol-To a mixed solution of 101.5 g of pure water and 406.1 g of methanol was added 110.4 g of ethyl silicate-28 (SiO ₂ concentration; 28% by weight, manufactured by Tama Chemical Industry Co., Ltd.). After the addition, 89.5 g of 5% aqueous ammonia was added over 3 hours while the liquid was heated to maintain the temperature of the liquid at 65 ° C., whereby silica particles were generated in the liquid. The liquid after the addition was maintained at the same temperature for 1 hour to age the silica particles in the liquid. Then, from the liquid containing the silica particles, unreacted ethyl silicate, methanol and ammonia contained in the liquid were removed by ultrafiltration, and pure water was added at the same time, and the SiO ₂ concentration was 5% by weight.
A silica sol A in which silica particles having an average particle diameter of 100 Å were dispersed was obtained.

-Preparation of Alkoxysilane Partial Hydrolyzate- Concentrated nitric acid was added to a mixed solution of 357.1 g of ethyl silicate-28, 402.9 g of ethanol and 240.0 g of pure water to adjust the pH of the mixed solution to 1 Adjusted to .5.
The alkoxysilane partial hydrolyzate a was obtained by heating this mixed solution at 50 ° C. for 1 hour.

-Preparation of coating liquid- Silica sol A obtained as described above and alkoxysilane partial hydrolyzate a were mixed at a solid content weight ratio of 7/3 and then at 50 ° C for 1 hour. By heating, the silica sol and the partial hydrolysis product of the alkoxysilane were reacted. .. Then, a liquid containing this reaction product is mixed with an equal amount of a cation exchange resin and an anion exchange resin (AG501,
Deionization was carried out by passing through a column packed with Bio-Rad).

Then, the water and alcohol contained in this liquid were distilled off by a rotary evaporator, and then replaced with propylene glycol monopropyl ether to obtain Si.
A coating solution having an O ₂ concentration of 20% by weight was obtained.

-Manufacture of Semiconductor Device and Evaluation of Silica-Based Insulating Film- The ion concentration of the coating solution thus obtained was measured, and the coating solution was applied onto a silicon wafer at 4000 rpm by a spinner. p. m, and dried at 150 ° C for 5 minutes, then 450 ° C and 800 ° C in a nitrogen atmosphere.
By heating for 30 minutes at each temperature, the silica-based insulating film having the film thickness shown in Table 1 was formed on the silicon wafer.

The etching rate and relative dielectric constant of the obtained silica type insulating film were measured and evaluated as follows. (1) Etching rate The film thickness before and after the silicon wafer with a silica-based insulating film was immersed in a 0.5% HF aqueous solution for 5 minutes was measured, the film thickness difference Δd was calculated, and the value Δd / 5 was obtained as the etching rate. Evaluated as.

(2) Relative permittivity A vapor deposited film of aluminum was formed on the silica-based insulating film obtained as described above, and this was measured with an impedance analyzer as a measuring electrode.

The results are also shown in Table 1. In addition, the above coating solution was coated and dried in the same manner as above on a silicon wafer provided with aluminum wiring (aluminum film thickness: 1 μm) at a line and space pitch of 2 μm, and dried in a nitrogen atmosphere. By heating at a temperature of 450 ° C. for 30 minutes, a silica-based insulating film having a film thickness of about 5000 angstrom was formed.

A scanning electron micrograph of the cross section of the semiconductor device with a silica-based insulating film thus obtained was taken, and the presence or absence of cracks was judged from the obtained photo, and the silica-based film formed on the semiconductor device was judged. The film thickness a at the convex portion and the film thickness b at the concave portion of the insulating film were measured, and the flatness of the silica-based insulating film was evaluated by the following formula.

F (flatness) = b / a The closer the value of F to 1, the flatter the silica-based insulating film formed on the semiconductor device.

Table 2 shows the results of the above-mentioned determination of the presence of cracks and the results of the flatness evaluation of the silica-based insulating film formed on the semiconductor device.

[0068]

EXAMPLE 2 - Preparation of silica sol - pure water 203.0g methyl silicate in a mixed solution of methanol 812.2g -51 (SiO ₂ concentration: 51 wt%, Tama Chemical Industry Co., Ltd.) 121.6g After the addition, 150 g of 5% aqueous ammonia was added over 5 hours while heating the liquid to keep the temperature of the liquid at 45 ° C.
This produced silica particles in the liquid. The liquid after the addition was maintained at the same temperature for 1 hour to age the silica particles in the liquid. Then, the unreacted ethyl silicate, methanol and ammonia contained in the liquid are removed from the liquid containing the silica particles by ultrafiltration, and pure water is added at the same time, and the SiO ₂ concentration is 5% by weight. To obtain a silica sol B in which silica particles having a particle size of 110 Å were dispersed.

-Preparation of partial hydrolysis product of alkoxysilane- 196.1 g of methyl silicate-51, ethanol 6
1% ammonia water was added to a mixed solution of 83.9 g and pure water 120.0 g to adjust the pH of the mixed solution to 8.0. This mixed solution was heated at 50 ° C. for 1 hour to hydrolyze methyl silicate, and then the pH was adjusted to 2. with concentrated nitric acid.
It was adjusted to 5 and further heated at 50 ° C. for 30 minutes to obtain an alkoxysilane partial hydrolyzate b.

-Preparation of coating liquid-Same as in Example 1 except that the silica sol B thus obtained and the alkoxysilane partial hydrolyzate b were mixed in a solid content weight ratio of 1/1. Then, the reaction between the silica sol and the partial hydrolyzate of alkoxysilane, the deionization treatment of the solution containing the obtained reaction product and the solvent substitution were sequentially carried out to obtain a coating solution having a SiO ₂ concentration of 20% by weight.

-Manufacturing of Semiconductor Device and Evaluation of Silica-Based Insulating Film- The ion concentration of the coating liquid obtained as described above was measured in the same manner as in Example 1, and the semiconductor device was manufactured in the same manner as in Example 1. The produced silica-based insulating film was evaluated.

The results are shown in Tables 1 and 2.

[0073]

[Example 3] -Preparation of silica sol-Silica sol A obtained in Example 1 was subjected to deionization treatment in the same manner as in the coating liquid of Example 1 to obtain silica sol C.

-Preparation of Partial Hydrolyzate of Alkoxysilane-Partial Hydrolyzate of Alkoxysilane Obtained in Example 2
The solution containing the same was subjected to deionization treatment in the same manner as the coating solution of Example 1 to obtain an alkoxysilane partial hydrolyzate c.

-Preparation of coating liquid- The silica sol C thus obtained and the alkoxysilane partial hydrolyzate c were mixed in a solid content weight ratio of 3/7, and the same conditions as in Example 1 were applied. It was made to react with. Then, the liquid containing this reaction product was subjected to the same deionization treatment as in Example 1, the water and alcohol contained in this liquid were distilled off by a rotary evaporator, and then replaced with ethyl lactate to obtain SiO 2. ₂ A coating solution having a concentration of 20% by weight was obtained.

-Manufacture of Semiconductor Device and Evaluation of Silica-Based Insulating Film- The ion concentration of the coating liquid obtained as described above was measured in the same manner as in Example 1, and the semiconductor device was manufactured in the same manner as in Example 1. The produced silica-based insulating film was evaluated.

The results are shown in Tables 1 and 2.

[0078]

[Example 4] -Preparation of silica sol-While maintaining a mixed solution of 139.1 g of pure water and 169.9 g of methanol while heating at 60 ° C, the mixed solution of ethyl silicate-28 in water / methanol (ethyl) was added to the mixed solution. Silicate; 532.5 g, water / methanol mixed solvent; 2450 g, water / methanol weight ratio; 1/4) 2
982.5 g and 596.4 g of 0.25% aqueous ammonia were simultaneously added over 52 hours, thereby forming silica particles in the mixed solution. The liquid after the addition was maintained at the same temperature for 3 hours to age the silica particles in the liquid. Then, unreacted ethyl silicate, methanol and ammonia contained in the liquid are removed from the liquid containing the silica particles by ultrafiltration, and at the same time pure water is added,
A silica sol D having a SiO ₂ concentration of 10% by weight and having silica particles having an average particle diameter of 250 Å dispersed therein was obtained.

-Preparation of partially hydrolyzed alkoxysilane-454.5 g of methyltrimethoxysilane, ethanol 1
Concentrated nitric acid was added to a mixed solution of 85.5 g and pure water 360.0 g to adjust the pH of the mixed solution to 1.0. This mixed solution is heated at 50 ° C. for 2 hours to partially hydrolyze the alkoxysilane.
Aqueous ammonia was added to adjust the pH to 7.0, and this solution was heated at 50 ° C. for 2 hours to obtain an alkoxysilane partial hydrolyzate d.

-Preparation of coating liquid- Silica sol D obtained as described above and alkoxysilane partial hydrolyzate d were mixed at a solid content weight ratio of 7/3, and the same as in Example 3. Reaction of silica sol with partial hydrolysis product of alkoxysilane, deionization treatment of the liquid containing the obtained reaction product, and solvent replacement are sequentially carried out, and Si
A coating solution having an O ₂ concentration of 20% by weight was obtained.

—Manufacture of Semiconductor Device and Evaluation of Silica-Based Insulating Film— The ion concentration of the coating liquid obtained as described above was measured in the same manner as in Example 1, and the semiconductor device was manufactured in the same manner as in Example 1. The produced silica-based insulating film was evaluated.

The results are shown in Tables 1 and 2.

[0083]

[Example 5] -Preparation of silica sol-In place of ethyl silicate-28, 169.4 g of methyltrimethoxysilane and ethyl silicate-28 266.
A silica sol was prepared in the same manner as in Example 4 except that 3 g was used to obtain silica sol E in which silica particles having a SiO ₂ concentration of 10% by weight and an average particle diameter of 250 Å were dispersed.

-Preparation of Partial Hydrolyzed Alkoxysilane- 17.3% ammonia water was added to a mixed solution of 227.3 g of methyltrimethoxysilane, 357.1 g of ethyl silicate-28, 175.0 g of ethanol and 240.0 g of pure water. The pH of the mixed solution was adjusted to 8.5. The mixed solution is heated at 50 ° C. for 2 hours to partially hydrolyze the alkoxysilane.
An aqueous acetic acid solution was added to adjust the pH to 4, and this solution was heated at 50 ° C. for 5 hours to obtain an alkoxysilane partial hydrolyzate e.

-Preparation of coating liquid-Same as in Example 3 except that the silica sol E thus obtained and the alkoxysilane partial hydrolyzate e were mixed at a solid content weight ratio of 4/1. The silica sol was partially reacted with the alkoxysilane partially hydrolyzed product, and the solution containing the obtained reaction product was sequentially subjected to deionization treatment and solvent substitution to obtain a coating liquid having a SiO ₂ concentration of 20% by weight.

-Manufacturing of Semiconductor Device and Evaluation of Silica-Based Insulating Film- The ion concentration of the coating liquid obtained as described above was measured in the same manner as in Example 1, and the semiconductor device was manufactured in the same manner as in Example 1. The produced silica-based insulating film was evaluated.

The results are shown in Tables 1 and 2.

[0088]

[Comparative Examples 1 to 4] A coating solution was prepared in the same manner as in Examples 1, 2, 4, and 5 except that the coating solution was not deionized, and the ion concentration of the resulting coating solution was determined in Example 1. The semiconductor device was manufactured in the same manner as in Example 1 and the obtained silica-based insulating film was evaluated.

The results are shown in Tables 1 and 2.

[0090]

[Table 1]

[0091]

[Table 2]

From the results shown in Table 1, the silica-based insulating films formed on the semiconductor devices of Examples 1 to 5 are all Comparative Examples 1 to 5.
No. 4, the relative dielectric constant and the etching rate are smaller than those of the silica-based insulating film formed on any of the semiconductor devices, and therefore it is judged that the semiconductor device is dense.

From the results shown in Table 2, the silica-based insulating films formed on the semiconductor devices of Examples 1 to 5 are all compared with the silica-based insulating films formed on any of the semiconductor devices of Comparative Examples 1 to 4. However, it has excellent flatness.

As is clear from the above, according to the present invention, a semiconductor device having a silica-based insulating film which is superior to the conventional one is provided.

Claims (2)

[Claims] 1. The general formula R _n Si (OR ′) _4-n (wherein
R and R'represent an alkyl group having 1 to 8 carbon atoms, an aryl group or a vinyl group, and n is an integer of 0 to 3. ) A silica sol (A) obtained by hydrolytic polycondensation of an alkoxysilane represented by the formula (1) and a reaction product of the alkoxysilane represented by the above formula or a partial hydrolyzate thereof (B), and having an ion concentration of 1. A semiconductor device having a silica-based insulating film formed from a coating liquid for forming a coating film, which is 0 mmol / liter or less. 2. A solution containing at least the silica sol (A), the alkoxysilane represented by the above formula or its partial hydrolyzate (B) and a coating solution for forming a film, treated with a cation exchange resin and treated with an anion. A coating solution for forming a film having an ion concentration in the coating solution for forming a film of 1.0 mmol / l or less is applied to a semiconductor substrate by heat treatment with an ion exchange resin, and the resulting coating film is cured by heating. A method of manufacturing a semiconductor device, comprising the step of forming a silica-based insulating film.