JPH04180977A - Production of coating fluid for forming silica film, coating fluid for forming silica film, production of silica film, silica film, and semiconductor device coated with silica film - Google Patents

Abstract

PURPOSE:To obtain a coating fluid for forming a silica film, which scarcely causes nonuniformity in coating and can form an insulating film of high flatness by dissolving at least two specified alkoxysilane compounds in specified organic solvents to cause hydrolysis and polycondensation. CONSTITUTION:In the synthesis of a siloxane polymer by the hydrolysis and polycondensation of at least two alkoxysilane compounds shown by the general formula: R4-nSi(OR')n (wherein R is 1-3C alkyl or aryl; R' is 1-3C alkyl; (n)is an integer of 2 to 4), at least two polar solvents different in boiling point are used so that at least three solvents are present including alcohol produced as the result of the hydrolysis. It is desirable to use a mixture of at least three solvents including the produced alcohol, selected in such a manner that, when arranged in the order of their boiling points, they are different in boiling point by at most 10 deg.C from one another.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing a coating liquid for forming a silica-based film.

Coating liquid for forming a silica-based film, method for producing a silica-based film,
The present invention relates to a silica-based coating and a semiconductor device formed with a silica-based coating.

(Prior Art) In recent years, with the development of VLSI manufacturing technology, there has been a demand for advanced multilayer wiring technology with high integration, high speed, and multifunctionality. For example, in the manufacturing of VLSIs, it is necessary to form wiring patterns and insulating films on the substrate.
At this time, a level difference is generated on the substrate, and it is difficult to further form a wiring pattern on the substrate having this level difference, so a planarization process to eliminate one level difference is essential.

Conventionally, as a planarization technique for eliminating such a step metal on a substrate, for example, a method using an organic material such as silicon ladder, polyimide, or polyimide silico is known. However, the film obtained is easily thermally decomposed at a temperature of about 300 to 450°C, and has the drawback of poor heat resistance and moisture resistance.

Further, the film is formed by dabbing the substrate with charged particles so as not to contain residual gases such as hydrogen, oxygen, and nitrogen in the substrate. A so-called bias sputtering method is known. Although this method is suitable for planarizing minute areas, it has the disadvantage of damaging the underlying substrate during the film accumulation process.

-Make a heavy-duty solution by dissolving silanol and alkyl 7-ranol in an organic solvent, use this coating solution to fill in the steps and apply the entire surface carefully, and then form a silica-based film by heat treatment. and flatten it. The so-called Subino-on-glass method (SOG coating method) is generally put into practical use. but.

When the above-mentioned coating solution is spin-coated onto a substrate such as an LSI as described above, radial coating unevenness occurs from the center of rotation of the substrate toward the periphery, causing variations in the thickness of the formed film and flattening of steps. There were drawbacks that impaired the Therefore, semiconductor devices manufactured by forming such a silica-based film have problems in reliability, such as a tendency for some wiring to be disconnected.

(Problems to be Solved by the Invention) The purpose of the present invention is to solve the problems of the conventional technique described above, and to develop a novel silica-based coating that can form an insulating film that is less likely to cause uneven coating and has high flatness. A method for producing a forming coating liquid,
Coating liquid for forming silica-based films.

The present invention provides a method for forming a silica-based film, a silica-based film, and a highly reliable semiconductor device using the silica-based film.

(Means for Solving the Problems) In view of the above problems, the present inventors have conducted extensive research and have found that:
The inventors have discovered that the above object can be achieved by a solution obtained by dissolving at least 2 ait of a specific alkoxysilane compound in a specific organic solvent and hydrolyzing the solution.

That is, 1 the present invention has the general formula (I) Rn-n 5i(OR')n (I)(
In the formula, R is an alkyl group having 1 to 3 carbon atoms or an IJ-al group,
Rr represents an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 2 to 4. ) A coating for forming a silica-based film using three or more types of solvents, including alcohols produced as a result of different boiling points, when synthesizing a siloxane polymer by hydrolyzing and condensing at least two types of alkoxysilane compounds represented by Method of manufacturing liquid.

A coating liquid for forming a silica-based film obtained by this manufacturing method, applying this coating liquid for forming a silica-based film onto a substrate,
After drying at 50-250℃, drying at 260-6℃ under nitrogen atmosphere.
The present invention relates to a method for producing a silica-based coating that is heat-cured at 00°C, a silica-based coating obtained by this production method, and a semiconductor device on which this silica-based coating is formed.

As the alkoxysilane compound represented by the general formula CI+ used in the present invention, the general formula (ff), (l[D
or Jun8 i (OR')4 tI[
lR8i (OR' )s (
m) & S i (OR')2
Compounds represented by (2) (wherein R and R' are the same as above) are mentioned. When R and R' are alkyl groups, they may be the same or different.

A specific example of the tetraalkoxysilane compound represented by the general formula (II) is tetramethoxy 7rane.

Tetraethoxysilane, tetrapropoxysilane.

Tetraisogloboxysilane, Tetrabutoxy 7rane,
Tetrainbutoxysilane, tetraphenoxyfurano 2
Tetra(2-methoxyethoxy)silane, Tetra(2-
ethoxyethoxy)silane.

Tetra(2-propoxyethoxy)silane, Tetra(2-propoxyethoxy)silane
-butoxyethoxy)silane, tetra(3-methoxypropoxy)silane, tetra(3-ethoxypropoxy)
7ran, tetra(3-propoxypropoxy)silane,
Examples include tetra(3-butoxypropoxy)silane. Especially Tetrapokuchipoki7silane and Tetraingloboquinsilane.

Tetrabutoxysilano and tetrabutoxysilane are preferably used.

A specific example of the trialfoxy/furan compound represented by the general formula is methyltrimethoxysilane.

Methyltriethoxy 7ran, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltriimproboxylsilane, phenyltrimethoxysilane, phenyltriethquin 7ran, Phenyltripropoxysilane, phenyltriisopropoxysilane, methyltri(2-methoxyethoxy)silane, methyltri(2-ethoxyethoxy)7ran, methyltri(2-propoquinethoxy)silane, methyltri(2-butoxyethoxy) Cyrano, methyltri(
3-butoxypropoxy)silane, methyltri(3-ethoxyproboxy/nosilane), methyltri(3-propoxypropoxy)silane, methyltri(3-butquinpropoquino)7rane, etc. Particularly methyltripropoquine7rane, methyl Triisopropoxysilane, methyltributoxysilane, and methyltriptoxysilane are preferably used.

A specific example of the dialkoxysilane compound represented by the general formula is dimethyldimethoxysilane.

Dimethyljethoxysilane, dimethyldipropoxysilane, dimethyldiisopropoxy 7rane, diethyldimethoxysila/, diethyljethoxy 7rane, diethyldibroboxysilane, diethyldiisoproboxysilane, diphenyldimethoxysila/, diphenyljethoxy 7rane Ran, diphenyldipropoxysilane, dimethyldiisopropoxy 7ran, dimethyldi(2-methoxyethoxy)
Silane, dimethyldi(2-ethoxyethoxy)silane,
Dimethyldi(2-propoxyethoxy)silane, dimethyldi(2-butoxyethoxy)silane, dimethyldi(2-propoxyethoxy)silane, dimethyldi(2-butoxyethoxy)silane,
3-methoxypropoxy) silane, dimethyldi(3-ethoxypropoxy)silane, dimethyldi(3-propoxypropoxy)silane, dimethyldi(3-butoxypropoxy) silane, and the like. In particular, dimethyldiproboxoxosilane, dimethyldiimpropoxysilane, dimethyldibutoxysilane and dimethyldiimbutoxysilane are preferably used. Two or more types of alkoxysilane compounds represented by general formula (II), I[), or formula may be used in combination.

Also, methanol and ethanol are polar solvents.

Propa Tool, Impropa Tool, Butanol.

Isobutanol, 2-butanol, tetrabutanol,
Alcohols such as be/tyl alcohol, 2-pentyl alcohol, 3-pentyl alcohol, impentyl alcohol, ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl butyl ketone, ethyl formate, Propyl formate.

Esters such as isobutyl formate, butyl formate, pentyl formate, methyl acetate, ethyl acetate, impropyl acetate, propyl acetate, butyl acetate, isobutyl acetate, 5ec-butyl acetate, ethylene glycol dimethyl ether, ethylene glycol dimethyl ether, ethylene glycol monomethyl ether, Ethylene glycol monoethyl ether.

There are glycol ethers such as propylene glycol monomethyl ether, propylene glycol monomethyl ether, and propylene glycol monoglobyl ether, and two or more types are mixed and used based on their boiling points. Even when there are two types of solvents, the third solvent is the alcohol produced by the hydrolysis reaction of the alkoxysilane compound9.The final solvent in the coating solution is the afi type.

Including alcohol produced by hydrolysis reactions.

Arrange at least three types of solvents in order of boiling point.

Find the difference in boiling points between adjacent solvents, and if the difference between these boiling points is 1
It is preferable to use a mixed solvent selected so that the temperature is 0°C or lower, more preferably 5°C or lower.

As the catalyst, organic acids such as formic acid, maleic acid, fumaric acid, and acetic acid, inorganic acids such as hydrochloric acid, phosphoric acid, nitric acid, and halonic acid, and alkalis such as ammonia and trimethylammonium are used. These catalysts are used in an appropriate amount depending on the amount of the alkoxysilane compound used as a raw material, but are preferably used in an amount of 0.001 to 0.5 mol per mol of the alkoxy 7-lane compound.

The amount of water used for hydrolyzing the alkoxysilane compound can be determined appropriately, but if it is too little or too much, there are problems such as a decrease in the storage stability of the coating solution. /0.5 per mole of compound
It is preferable to set it as the range of -4 mol.

The silica-based film is formed by applying the coating solution for forming a silica-based film onto the substrate using a spinner, brush, spray, etc.
After drying at a temperature of 50 to 250°C, preferably 100 to 200°C, drying at 260 to 600°C, preferably 4
Curing is carried out by heating at a temperature of 00 to 500°C.

The coating liquid of the present invention can be generally applied to semiconductor devices.
Used for panocyblation membranes, etc.

A metal wiring such as aluminum is provided, and P-8iO is placed on it.
Film (silicon oxide [) formed by plasma CVD method, TE
The coating liquid for forming a silica-based film of the present invention is applied onto a semiconductor substrate on which a 01 film (a film formed from tetraethoxysilano) or the like is formed, and the coating liquid for forming a silica-based film of the present invention is heated and cured to form a P film on this semiconductor substrate.
A silica-based film is formed on the -8iO film or the like.

By such a method, the silica-based film formed using the coating liquid for forming a silica-based film of the present invention flattens unevenness caused by wiring etc. in the semiconductor device, improves processing accuracy, and finally completes the process. Device reliability is greatly improved.

(Examples) The present invention will be explained below using examples, but the invention is not limited to these examples.

The maximum coating unevenness was measured as follows.

Maximum coating unevenness> Due to unevenness on the pattern, streak-like coating unevenness occurs toward the periphery of the pattern.
Using l[At-, the surface unevenness was measured with a sweep width of t-10 mm perpendicular to the streak-like coating unevenness, and the thickness of the largest protrusion among them was taken as tMaxHT. This measurement was performed at five points on the pattern, and the average AV0MaxHT of MaxHT was determined.

Furthermore, since the thickness of the silica-based film formed differs depending on the type of solvent, the maximum coating unevenness was calculated using the following formula when the thickness of 2M was t-0 and 3 μm.

Examples 1 to 5 General formula (111 dishes) or (goods) 8 i (OR') 4 (
II) R8i (OR')3
(It1'hsi (OR')2
Qv) in which R is a methyl group, the molar ratio of the alkoxysilane compound represented by the general formula (I
[1:[l:M] was mixed at a ratio of 2=2:l so that the total amount was 1 mole.

At this time, (I[) (DI) (Iv) Formula no R
'U same! : l,, As shown in Table 1, R' is -
CH5 or -CzHs.

Solvent Fi Using the mixed solvent shown in Table 1, the total weight of 1 mol of the mixed solution of the above alkoxysilane compound and the solvent is 5.
Each sample was dissolved in each solvent to give a total weight of 0.00 g. In Table 1, when R' is -CH5, the amount of methanol is small because 10Z4 g of methanol is produced by hydrolysis of the alkoxysilane compound. Also, R' is -C
The reason why ethanol was not added during xHs is that 147.2 g of ethanol was similarly produced by hydrolysis. An aqueous solution prepared by dissolving 3 g of phosphoric acid in 40 g of pure water was added to this to perform hydrolytic polycondensation to prepare a coating solution for forming a silica film. The phosphorus aqueous solution was added dropwise over 30 minutes. When an aqueous solution of phosphoric acid was added dropwise, the temperature of the solution rose in some cases and in others it did not. In the cases in which the temperature did not rise, the temperature was raised by heating and maintained at 50° C. for 1 hour.

The coating solution for forming a silica-based film produced in this way was spin-coated onto the pattern at 3000 rpm using a spinner, and then coated on a hot plate at 150°C for 30 seconds and 250°C.
Heated at ℃ for 30 seconds. Furthermore, it was heat-cured for 30 minutes in a 450° C. curing oven. The pattern is p-8 on the surface with a step difference of 1 μm.
iOIIu'r formed TEG (TEST ELEM
(abbreviation of ENT GROUP) was used.

Next, the unevenness of the surface of the silica-based coating was measured on the flat part of the pattern, and the maximum coating unevenness was determined according to the above measurement method. The results are shown in Table 1.

Comparative Examples 1 to 9 Tetramethoxysilane, methyltrimethoxysilane, and dimethyldimethoxysilane were mixed in a molar ratio of 2=2=1 so that the total amount was 1 mole. Using methanol, ethanol, impropanol, n-propanol, 2-butanol, n-butanol, acetono, isopropyl acetate, and butyl acetate as the solvent, the total weight of 1 mole of the above alkoxysilane mixture and the solvent is 500 g. Each was dissolved as follows. An aqueous solution prepared by dissolving 3 gt of phosphoric acid and 40 g of pure water was added thereto to perform hydrolytic polycondensation to prepare a coating solution for forming a silica-based film.

The phosphoric acid aqueous solution was added dropwise over 30 minutes. When the phosphoric acid aqueous solution was added dropwise, the temperature of the solution rose, and when it reached 50°C or higher, it was cooled with water to keep it below 50°C.

The coating solution for forming a silica-based film thus prepared was spin-coated onto the pattern using a spinner at 3000 rpm in the same manner as in Example 1.
Heated at 0 seconds and 250°C for 30 seconds. Further 450℃
It was heat-cured for 30 minutes in a curing oven. The pattern has a step difference of 1μ.
TEG with a p-8iO film formed on its surface was used.

Next, the unevenness of the surface of the silica-based coating was measured on the flat part of the pattern, and the maximum coating unevenness was determined according to the above measurement method. The results are shown in Table 2.

As evident in Tables 1 and 2.

Comparing the examples and comparative examples shows that the maximum coating unevenness value of the examples is small.

Comparative Examples 10-11 Tetramethquine 7 Run 2 Methyltrimethoxy/Sila/,
Dimethyl dimethoxy/cyrano was mixed in a molar ratio of 2=2:1 so that the total amount was 1 mole. Using the mixed solvents shown in Table 3 as solvents, each was dissolved so that the total weight of 1 mol of the above alkoxysilane mixture and the solvent was 500 g. An aqueous solution prepared by dissolving 3 g of phosphoric acid in 40 g of pure water was added with vinegar to perform hydrolysis and X-condensation to prepare a coating solution for forming a silica-based film.

The phosphoric acid aqueous solution was added dropwise over 30 minutes. When the phosphoric acid aqueous solution was added dropwise, the temperature of the solution rose, and when it reached 50°C or higher, it was cooled with water to keep it below 50°C.

The coating solution for forming a silica-based film thus prepared was applied to the coating solution for 3000 rpm using a spinner in the same manner as in Examples and Comparative Examples.
Spin coat on the pattern with pm and apply on hot plate for 15 minutes.
Heated at 0°C for 30 seconds and at 250°C for 30 seconds. Furthermore, it was heat-cured for 30 minutes in a 450° C. curing oven. The pattern used was TEG on which a Kl)-8iO film was formed on the surface with a step difference of 1 μm.

Next, the unevenness of the surface of the silica-based coating was measured on the flat part of the pattern, and the maximum coating unevenness was determined according to the above measurement method. The results are shown in Table 3.
As is clear from Tables 1 and 3 in the margin below.

Comparison of all the examples and comparative examples 10 to 11 shows that the maximum coating unevenness value of the examples is small. That is.

Even if three or more types of solvents are used, if the boiling point of one type is extremely different from that of the other solvents, coating unevenness will increase.

(Effects of the Invention) According to the present invention, it is possible to produce a coating liquid for forming a silica-based film with small coating unevenness with 5T capability. By using this coating liquid for forming a silica-based film for an interlayer insulating film, a passivation film, etc. of a semiconductor device, planarization becomes possible and a highly reliable semiconductor device can be manufactured.

Agent Patent Attorney Kuni Wakabayashi ,−

Claims (1)

[Claims] 1. General formula (I) R_4_-_nSi(OR')_n(I) (wherein R is an alkyl group or aryl group having 1 to 3 carbon atoms,
R' represents an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 2 to 4. ) When synthesizing a siloxane polymer by hydrolyzing and condensing at least two types of alkoxysilane compounds represented by A method for producing a coating liquid for forming a silica-based film, the method comprising using three or more types of solvents. 2. Arrange at least three types of solvents, including the alcohol produced by the hydrolysis reaction, in order of their boiling points, determine the difference in boiling points between adjacent solvents, and select a solvent so that the difference in boiling points is 10°C or less. 2. The method for producing a coating liquid for forming a silica-based film according to claim 1, wherein the mixed solvent is used. 3. A coating liquid for forming a silica-based film obtained by the manufacturing method according to claim 1 or 2. 4. After applying the coating liquid for forming a silica-based film according to claim 1 or claim 2 onto a substrate and drying it at 50 to 250°C,
A method for producing a silica-based film, characterized by heat curing at 260 to 600°C in a nitrogen atmosphere. 5. A silica-based coating obtained by the manufacturing method according to claim 4. 6. A semiconductor device on which the silica-based film according to claim 4 is formed.