JP3214175B2 - Protective film material solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film material solution,
In particular, the present invention relates to an improved protective film material solution used for protecting a circuit formation surface when etching or polishing the back surface of a semiconductor substrate after circuit formation.

[0002]

2. Description of the Related Art In the manufacture of integrated circuits, after forming an integrated circuit on one surface of a semiconductor substrate such as a silicon wafer, it is necessary to remove impurities formed on the back surface of the substrate by ion implantation or the like and to reduce the thickness of the substrate. For the purpose, the back surface of the substrate is ground or polished by etching. At this time, the surface on which the integrated circuit is formed is covered with a protective film, and the protective film is peeled off after shaving the back surface. In a conventional integrated circuit manufacturing method, a protective film material solution obtained by dissolving a novolak resin in ethyl cellosolve acetate, methyl cellosolve, diglyme, or the like is used as a material for such a protective film. It is formed by applying a material solution to a surface of a semiconductor substrate on which an integrated circuit is formed by a conventional method and drying the applied solution.

[0003]

However, the protective film material solution used in the above-mentioned conventional method for manufacturing an integrated circuit includes:
The applicability to a substrate whose diameter has been increased with the recent increase in the degree of integration of integrated circuits is not sufficient. In other words, when spin coating is applied to a substrate having a diameter of 6 inches or more, which has not been regarded as a problem for a conventional substrate having a diameter of about 4 inches, the conventional protective film material solution is applied to the outer periphery of the substrate. Along with this, there is a problem that uncoated portion (repelling) is apt to occur, so that it is necessary to increase the coating amount and the film thickness becomes unnecessarily thick. Accordingly, an object of the present invention is to provide a protective film material solution having excellent coatability on a substrate having a large diameter.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by forming an integrated circuit on one surface of a semiconductor substrate having a diameter of 6 inches or more, and then forming the integrated circuit on the surface on which the integrated circuit is formed. A protective film material solution using a method for manufacturing an integrated circuit having a step of applying a protective film material solution, drying to form a protective film, and etching or polishing the other surface, wherein the protective film material solution is a novolak resin; And a solvent as a main component, and the solvent is a ketone having 7 or 8 carbon atoms,
An object of the present invention is to provide a protective film material solution containing at least one solvent selected from the group consisting of propylene glycol alkyl ethers and alkoxypropionic acid esters.

The semiconductor substrate used in the method of the present invention includes, for example, a substrate made of silicon, gallium arsenide, etc., and an integrated circuit is formed on the semiconductor substrate according to a conventional method. For example, in the case of a silicon planar transistor, (1) thermal oxidation of a silicon wafer, (2) etching of an isolation diffusion portion, (3) isolation diffusion, (4) etching of a base diffusion portion,
(5) Base diffusion, (6) Etching of the emitter diffusion portion in the base region, (7) Emitter diffusion, (8) Drilling of electrode contact in the emitter, base and collector regions, (9) Deposition of wiring material, (10) An integrated circuit is formed by a process such as etching of an unnecessary deposition surface. In order to form a protective film on the surface of the semiconductor substrate on which the integrated circuit is formed, a protective film material solution is spin-coated with, for example, a spinner and then dried on a hot plate or in a clean oven to remove the solvent.

The novolak resin used for forming the protective film in the present invention is not particularly limited, but has a polystyrene-equivalent weight average molecular weight (hereinafter, referred to as “Mw”) of 1, determined by gel permeation chromatography (GPC). Those having a molecular weight of 000 or more are preferred. When Mw is less than 1,000, the coating properties of the resulting protective film are likely to be poor, and there is a possibility that an unpleasant odor such as a monomer serving as a raw material of the novolak resin may be generated at the time of drying after applying the protective film material solution. . Mw of novolak resin is usually 3
Although it is not more than 0000, as long as no gel is generated, for example, about 50,000 can be used.

The novolak resin used in the present invention can be produced by a conventional method, for example, by subjecting a phenol and an aldehyde to addition condensation in the presence of an acid catalyst. Examples of phenols used in the production of novolak resins include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p
-Butylphenol, 2,3-xylenol, 2,4-
Xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, p-phenylphenol, hydroquinone, catechol, resorcinol, 2-methylresorcinol, pyrogallol, α-naphthol , Bisphenol A, dihydroxybenzoic acid ester, gallic acid ester and the like. Among these phenols, phenol, o-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol,
2,3,5-trimethylphenol, resorcinol,
2-Methylresorcinol and bisphenol A are preferred. These phenols can be used alone or in combination of two or more.

The aldehydes include, for example, formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropylaldehyde,
β-phenylpropyl aldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-
Hydroxybenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-
Examples include methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde, and among these aldehydes, formaldehyde, acetaldehyde and benzaldehyde are preferable. These aldehydes can be used alone or in combination of two or more.

The aldehyde is used in a proportion of usually 0.7 to 3 mol, preferably 0.7 to 2 mol, per 1 mol of the phenol. As the acid catalyst, an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid, or an organic acid such as formic acid, oxalic acid or acetic acid is used. The use amount of these acid catalysts is preferably 1 × 10 ^{-4 to} 5 × 10 ^-1 mol per mol of phenols.

In the condensation reaction, water is usually used as the reaction medium. However, when the phenol used in the condensation reaction does not dissolve in the aqueous solution of the aldehyde and becomes a heterogeneous system from the beginning of the reaction, the reaction medium is used as the reaction medium. Hydrophilic solvents can also be used. The solvent used at this time,
Alternatively, examples thereof include alcohols such as methanol, ethanol, propanol and butanol, and cyclic ethers such as tetrahydrofuran and dioxane. The use amount of these reaction media is preferably 20 to 1000 parts by weight per 100 parts by weight of the reaction raw materials. The reaction temperature of the condensation reaction can be appropriately adjusted according to the reactivity of the reaction raw materials, but is usually 0 to 200 ° C, preferably 70 to 15 ° C.
0 ° C. After completion of the condensation reaction, in order to remove unreacted raw materials, acid catalyst and reaction medium present in the system, the internal temperature is generally raised to 130 to 230 ° C., and volatile components are distilled off under reduced pressure to obtain novolak. Collect the resin.

Solvents used for preparing a protective film material solution used in forming a protective film by the method of the present invention include ketones having 7 or 8 carbon atoms, propylene glycol alkyl ethers and alkoxypropionate esters. It is necessary to contain at least one solvent selected from the group consisting of Examples of ketones having 7 or 8 carbon atoms include methyl amyl ketone, methyl isoamyl ketone, cypropyl ketone, diisopropyl ketone, ethyl butyl ketone, methyl hexyl ketone, ethyl pentyl ketone, and the like. Examples of the propylene glycol alkyl ethers include propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether and the like. Examples of the alkoxypropionates include methyl 2-methoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 2-ethoxypropionate, methyl 3-ethoxypropionate, and ethyl 3-ethoxypropionate. Butyl 3-ethoxypropionate, methyl 2-butoxypropionate, ethyl 3-butoxypropionate, and the like. Also,
These exemplified solvents can be used alone or in combination of two or more. Among the solvents exemplified above, methyl amyl ketone, propylene glycol methyl ether, propylene glycol butyl ether, and ethyl 3-ethoxypropionate are preferred.

As the solvent used in the present invention, a solvent other than the above-mentioned solvents can be added in a range that does not impair the effects of the present invention, for example, 50% by weight or less, particularly preferably 30% by weight or less. . Examples of other solvents other than the above include esters such as butyl acetate, isoamyl acetate, butyl propionate, ethyl butyrate, and butyl butyrate, and ketones such as diisobutyl ketone and acetylacetone.

The viscosity of the protective film material solution is 15 to 60.
0 cp (25 ° C.) is preferred, especially 15 to 400 cp.
(25 ° C.) is preferred. When spin coating is carried out using a spinner, if the rotation speed is the same, the higher the viscosity of the solution, the thicker the protective film formed, but the viscosity (25 ° C.) becomes 1
If the thickness is less than 5 cp, the formed film is too thin and pinholes are likely to be formed on the protective film. At this time, if the rotation speed of the spinner is reduced, the film becomes thick only at the end of the substrate and becomes Cracking tends to occur later. On the other hand, when the viscosity (25 ° C.) exceeds 600 cp, the viscosity is too large, so that the coating device cannot suck the protective film material solution and may not be coated. here,
The amount of the solvent can not be said sweepingly differs depending on the kind of solvent, but a resin solid concentration of the protective film material solution
It should be 10 to 50% by weight.

In the present invention, for example, a surfactant can be added as an additive to the protective film material solution.
Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; and polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether. Nonionic surfactants such as oxyethylene alkyl phenyl ethers, polyethylene glycol dilaurate, polyethylene glycol dialkyl ether such as polyethylene glycol distearate, F-top EF301, EF303, E
F352 [manufactured by Shin-Akita Chemical Co., Ltd.], MegaFac F17
1, F173 [manufactured by Dainippon Ink and Chemicals, Inc.]
No. 178242, a linear fluorine-containing surfactant having a fluoroalkyl group or a perfluoroalkyl group, Florado FC430, FC431 [manufactured by Sumitomo 3M Ltd.], Asahigard AG710, Surflon S-382, SC101, SC102, SC10
3, fluorinated surfactants such as SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), acrylic acid or methacrylic acid (co) polymer polyflow No. . 75, no. 95 [Kyoeisha Yushi Chemical Industry Co., Ltd.
Manufactured). These surfactants alone,
Alternatively, two or more kinds are used in combination. The amount of the surfactant to be added is generally 2 parts by weight or less, preferably 1 part by weight or less, per 100 parts by weight of the novolak resin.

In the present invention, the protective film material solution is applied to the surface on which the integrated circuit is formed and dried to form a protective film having a thickness of about 0.5 to 20 μm, and then the other surface is etched. Or polished. As an etching method, a method of dipping in an etchant such as hydrofluoric acid or nitric acid, a method of dry etching with a plasma etching apparatus, or the like is used. When the protective film is peeled off from the substrate, a peeling solution is used. As the peeling solution, for example, N-methyl-2-pyrrolidone, N-ethyl-
2-pyrrolidone, N-propyl-2-pyrrolidone, N-
Hydroxymethyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, N-hydroxypropyl-2-
Lactams such as pyrrolidone and caprolactam; 1,3
-Dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2
Imidazolines such as imidazolidinone and 1,3,4-trimethyl-2-imidazolidinone; morpholine,
Morpholines such as -methylmorpholine, 4-ethylmorpholine, 4-hydroxymethylmorpholine, 4-hydroxyethylmorpholine, 4-aminomethylmorpholine, 4-aminoethylmorpholine, 4-aminopropylmorpholine; N, N-dimethylformamide; Amides such as N, N-dimethylacetamide, sulfoxides such as dimethylsulfoxide and diethylsulfoxide, sulfones such as sulfolane, dimethylsulfone and diethylsulfone, 2-ethylhexylamine, polyethyleneimine, 1,4-diaminobutane, N- Amines such as aminoethylpiperazine, isopropanolamine, N
-Hydroxyethylpiperazine, diisopropanolamine, aminoethylethanolamine, N, N-diethylethanolamine, N-methyl-N, N-diethylethanolamine, N, N-diisopropylethanolamine, N, N-dibutylethanolamine, Amino alcohols such as N, N-diethanolamine and N, N, N-triethanolamine; ketones such as acetylacetone, cyclohexanone and methyl isobutyl ketone;
Ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, cellosolve acetate, methyl cellosolve acetate, butyl cellosolve acetate, cellosolve and the like ethylene glycols and derivatives thereof, diethylene glycol, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, A single solution or a mixture of two or more of diethylene glycols and derivatives thereof such as diethylene glycol monomethyl ether and diethylene glycol monopropyl ether, triethylene glycols and derivatives thereof such as triethylene glycol and triethylene glycol monoethyl ether, and organic sulfonic acids. To mention Kill. In the present invention, the protective film can be completely removed only by immersion in the above-mentioned stripping solution for, for example, 0.5 to 15 minutes and washing with water.

[0016]

Next, the present invention will be described in detail with reference to examples. Examples 1 to 10 and Comparative Examples 1 to 3 In a 5-liter separable flask equipped with a stirrer, cooling tube and thermometer, 324 g (3 mol) of m-gresol, 216 g (2 mol) of p-cresol, 37% by weight
385 g of formaldehyde aqueous solution (formaldehyde:
4.75 mol) and 0.35 g of oxalic acid, and the separable flask was immersed in an oil bath and reacted for 6 hours while keeping the internal temperature at 100 ° C. Thereafter, the temperature of the oil bath was set to 180
C. and at the same time, the pressure in the separable flask was reduced to remove volatile components to obtain a novolak resin.

The Mw of the obtained novolak resin was converted to a GPC column (Two G2000H6, manufactured by Toyo Soda Kogyo Co., Ltd.).
G3000H6, G4000H6) and tetrahydrofuran as the eluting solvent, and found to be 6,900 by gel permeation chromatography. 30 parts by weight of this novolak resin was dissolved in 70 parts by weight of a solvent shown in Table 1 to obtain a protective film material solution. The viscosity of the solution at 25 ° C. was measured by Tokyo Keiki Co., Ltd.
The viscosity was as shown in Table 1 when measured with an E-type viscometer. The obtained protective film material solution is supplied with a pore size of 0.2 μm.
The particles were removed by filtration with a filter of m. Each protective film material solution is spin-coated on the integrated circuit surface of an 8-inch diameter silicon wafer on which an integrated circuit is formed by a usual method using a spinner, and then 150 μm on a hot plate.
Drying was performed at 2 ° C. for 2 minutes to form a protective film having a dry film thickness of 1.5 μm. By observing the formed protective film with an optical microscope, applicability such as the presence or absence of unpainted portions was examined. Table 1 shows the results.

[0018]

[Table 1]

[0019]

According to the protective film material solution of the present invention, the surface on which an integrated circuit is formed can be protected well when the other surface is polished or etched by polishing, and the diameter is 6 mm.
It has excellent applicability to substrates having a diameter larger than an inch, and can be advantageously used for producing integrated circuits.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21 / 304,21 / 306,21 / 308

Claims (2)

(57) [Claims] An integrated circuit is formed on one surface of a semiconductor substrate having a diameter of 6 inches or more , a protective film material solution is applied to the surface on which the integrated circuit is formed, and dried to form a protective film. In a protective film material solution used in a method for manufacturing an integrated circuit having a step of etching or polishing a surface, the protective film material solution mainly contains a novolak resin and a solvent, and the solvent has 7 or 8 carbon atoms. At least one selected from the group consisting of monoketones, propylene glycol alkyl ethers and alkoxypropionates
A protective film material solution comprising a kind of solvent. 2. The method according to claim 1, wherein the application of the protective film material solution is performed by a spinner.
2. The method according to claim 1, wherein
liquid.