JP2914852B2 - Circuit protection film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit protection film formed on a surface of a semiconductor substrate such as a silicon wafer, and more particularly to a circuit protection film having resistance to acid etching.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, for example, after a large number of identical circuits are formed on a substrate such as a silicon wafer, acid etching is performed to adjust the thickness of the wafer. 2. Description of the Related Art There is known a method of separating and commercializing individual circuits. However, there is an inconvenience that a circuit formed on the silicon wafer is damaged in the process of the acid etching.

[0003]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to form a circuit on a silicon wafer surface which can prevent damage to the circuit on a silicon wafer when the circuit is formed by acid etching. To provide a film for protecting a circuit.

[0004]

According to the present invention, there is provided a compound represented by the following general formula (1):

[0005]

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[Wherein X is a formula:

[0007]

Embedded image A tetravalent organic group selected from the group consisting of
formula:

[0008]

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A divalent organic group selected from the group consisting of And a structural unit (A) represented by the general formula (2):

[0010]

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Wherein X is as described above, a plurality of R ¹ may be the same or different, and are a divalent organic group having 1 to 8 carbon atoms, and a plurality of R ² are the same or different. Is a monovalent organic group having 1 to 8 carbon atoms, and Z is a group represented by the formula: —O—, —CH ₂ CH ₂ —, and

[0012]

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Is a divalent group selected from the group consisting of And the number of moles m of the structural unit (A) contained in one molecule and the number of moles n of the structural unit (B) contained in one molecule Is m / n = 95 /
Provided is a circuit protection film formed on the surface of a semiconductor substrate containing an organosilicon-modified polyimide compound of 5 to 70/30.

The inventors have found that the organosilicon-modified polyimide compound containing the above structural units (A) and (B) has acid resistance and
When it can withstand acid etching because it shows oxidation resistance,
They have found that they have excellent adhesion to a silicon wafer, and that they are soluble in several organic solvents and can be completely peeled off from the silicon wafer after acid etching, and have completed the present invention.

Organosilicon-Modified Polyimide Compound The organosilicon-modified polyimide compound, which is an effective component of the circuit protective film of the present invention, comprises a structural unit (A) represented by the above formula (1) and a compound represented by the above formula (2). It contains the structural unit (B) represented. In addition, the organosilicon-modified polyimide compound 1
A plurality of Xs contained in the molecule may be the same or different,
A plurality of Y may be the same or different. When a plurality of Zs exist in one molecule, they may be the same or different.

The number of moles of the structural unit (A) contained in one molecule of the organosilicon-modified polyimide compound is m
And the number n of moles of the structural unit (B) is m / n = 95/5 to 5.
It is necessary to meet 70/30.

In the general formula (2), R ¹ is a group having 1 carbon atom.
~ 8 divalent organic groups, specifically,

[0018]

Embedded image Etc. are exemplified.

R ² in the above general formula (2) is a monovalent organic group having 1 to 8 carbon atoms, specifically, a methyl group,
Ethyl group, n-propyl group, i-propyl group, n-butyl group,
Examples include a phenyl group.

The degree of polymerization of the organosilicon-modified polyimide compound is preferably in the range of 20 to 3,000, more preferably in the range of 50 to 1500.

Production of Organosilicon-Modified Polyimide Compound The above organosilicon-modified polyimide compound is, for example, of the formula
(3-1)-(3-4):

[0022]

Embedded image At least one of the tetracarboxylic dianhydrides represented by
Species, formulas (4-1) to (4-3):

[0023]

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At least one of the diamine compounds represented by
Species and formulas (5-1) to (5-3):

[0025]

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(Wherein R ¹ and R ² are as defined above), and reacted in a suitable solvent with at least one of the silicon diamine compounds represented by the general formula (6):

[0027]

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(Wherein, X and Y are as described above)
Structural unit (a) represented by and general formula (7):

Embedded image (Wherein X, Z, R ¹ and R ² are as defined above), after producing a polyamic acid containing the structural unit (b), the polyamic acid is heated to effect dehydration and ring closure. It can be manufactured by the following.

The above-mentioned polyamic acid can be produced by the following conventionally known method. For example, the above equation (3-
1) tetracarboxylic dianhydride represented by (3-4),
The diamine compound represented by the above formulas (4-1) to (4-3) and the silicon diamine compound represented by the above formulas (5-1) to (5-3) are appropriately mixed under an inert gas atmosphere. When it is dissolved in a solvent as much as possible, and usually mixed and stirred at a temperature of 80 ° C. or lower, preferably room temperature or lower, the polymerization reaction proceeds promptly, the viscosity of the solution gradually increases, and polyamic acid is generated.

The above-mentioned polyamic acid is usually
By heating to 00 to 200 ° C., the polyamic acid undergoes dehydration and ring closure to obtain the organosilicon-modified polyimide compound. In order to facilitate dehydration at the time of performing such dehydration ring closure, an azeotropic dehydrating agent such as toluene or xylene is preferably used.

The production of the above-mentioned polyamic acid, the dehydration ring-closure reaction of the polyamic acid, and the preparation of a coating solution described later include:
Use an inert solvent. The solvent does not need to be able to dissolve all of the tetracarboxylic dianhydride, diamine compound and silicon diamine compound used, but one that can dissolve the resulting polyamic acid and organosilicon-modified polyimide compound. preferable.

Examples of the solvent include tetrahydrofuran, 1,4-dioxane, diethylene glycol dimethyl ether, methyl cellosolve, ethyl cellosolve, butyl cellosolve, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, γ-butyrolactone, Butyl cellosolve acetate, butyl acetate, ethyl acetate, N-
Methyl-2-pyrrolidone, N, N-dimethylacetamide, N,
N-dimethylformamide and the like are exemplified, and these can be used alone or in combination of two or more.

Preparation of Coating Solution for Forming Circuit Protection Film When a circuit protection film is formed on the surface of a silicon wafer, the coating solution is prepared by dissolving the above organosilicon-modified polyimide compound in an appropriate solvent. Use as The use of a coating liquid improves workability and facilitates adjustment of the film thickness. As such a coating solution, the solution containing the organosilicon-modified polyimide compound produced as described above can be used as it is or diluted with the above-mentioned solvent. Alternatively, the solution containing the organosilicon-modified polyimide compound is poured into methanol with stirring, or hexane is added to the solution with stirring to precipitate the organosilicon-modified polyimide compound, and the polyimide compound is filtered off. It is also possible to dissolve in the above-mentioned solvent to obtain a coating solution. In addition, the viscosity of the coating liquid, taking into account the workability at the time of coating the silicon wafer surface described below,
A range from 3000 to 15000 cSt is preferred.

Formation of Film The circuit protection film of the present invention can be formed by, for example, a method similar to a conventionally known method of forming a commonly used film made of polyimide on a silicon wafer. For example, after applying the coating solution on a surface of a silicon wafer on which circuits are formed by a spin coater and pre-baking, the wafer is placed in an oven and the organosilicon-modified polyimide compound is cured to cure the circuit protective film. Can be formed.

The rotation speed of the spin coater is 1,000 to
A range of 5000 rpm is preferred, and a range of 1500 to 3000 rpm is particularly preferred.

The curing temperature of the organosilicon-modified polyimide compound is preferably in the range of 150 to 400 ° C.
Particularly, the range of 200 to 300 ° C is preferable.

The thickness of the circuit protection film to be formed is 5
The range is preferably from 20 to 20 μm, and particularly preferably from 5 to 15 μm.

The silicon wafer having the circuit protection film formed on the surface on which the etching circuit is formed is immersed in, for example, a mixed solution of hydrofluoric acid and nitric acid to acid-etch the surface of the wafer where the circuit is not formed. By doing so, the thickness of the wafer can be adjusted without damaging the circuits. In such acid etching, acetic acid is preferably added as a diluent to a mixed solution of hydrofluoric acid and nitric acid. When acetic acid is added, it is preferable that acetic acid is contained in an amount of 10 to 50% by weight. The temperature of the mixed solution of hydrofluoric acid and nitric acid in the case of acid etching is preferably in the range of 0 to 50 ° C.

After completion of the acid etching treatment, the wafer is washed with water and dried, and then washed with an organic solvent described below, whereby the circuit protective film can be peeled off. Organic solvents used for washing include, for example, tetrahydrofuran, N, N-
Dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, N-methyl-2-pyrrolidone and the like are used, and these are used alone or as a mixed solvent of two or more.

[0040]

Examples of the present invention will be described below. However, the following examples are for explaining the present invention, and the present invention is not limited thereto.

Example 1 A 500 ml separable flask was charged with 44.42 g (0.10 mol) of 2,2'-bis (3,4-benzenedicarboxylic acid anhydride) perfluoropropane (6FDA) and 96 g of γ-butyrolactone. In the flask, 2,2-bis [4- (4
-Aminophenoxy) phenyl] propane (BAPP) 3
6.95 g (0.09 mol) and 1,3-bis (3-aminopropyl)-
1.49 g of 1,1,3,3, -tetramethyldisiloxane (APM)
0.01 mol) in 100 g of γ-butyrolactone was added dropwise, and the mixture in the flask was stirred overnight to produce a polyamic acid. Next, 30 g of toluene was added to the mixture, and the mixture was heated to 170 ° C. to dehydrate and ring-close the polyamic acid. Thus, the formula in one molecule
(8):

[0042]

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And 90 mol% of a structural unit represented by the following formula (9):

[0044]

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A solution of an organosilicon-modified polyimide compound containing 10 mol% of a structural unit represented by the following formula was obtained. The viscosity of the solution was 5900 cSt.

The solution of the organosilicon-modified polyimide compound obtained above was applied to one surface of a silicon wafer at 1500 rpm / 30 sec using a spin coater. Next, the silicon wafer was heated at 150 ° C. for 30 minutes, and further heated at 250 ° C. for 1 hour to form a film containing the organosilicon-modified polyimide compound represented by the general formula (6).

The wafer having a film formed on one side as described above is immersed in a mixed solution of 3% of 50% hydrofluoric acid + 3% of 40% nitric acid + 4 volumes of acetic acid for 4 minutes to remove the surface on which the film is not formed. Acid etched. Thereafter, even if the wafer was washed with water and dried, no peeling of the formed film was observed. Next, the washed and dried wafer was immersed in tetrahydrofuran, and washed with an ultrasonic cleaner to dissolve the film. The surface on which the film was formed was protected, and no residue of the formed film was observed.

Example 2 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] -propane (BPADA) was placed in a 500 ml separable flask.
62.42 g (0.12 mol) and 94 g of γ-butyrolactone were charged, and 2,4-diaminotoluene (T
DA) 13.19 g (0.108 mol) and 1,3-bis (3-aminopropyl) -1,1,3,3, -tetramethyldisiloxane (APM)
A solution of 2.98 g (0.012 mol) dissolved in 100 g of γ-butyrolactone was added dropwise, and the mixture in the flask was stirred overnight to produce a polyamic acid. Next, 30 g of toluene was added to the obtained reaction mixture, and the mixture was heated to 170 ° C. to dehydrate and close the polyamic acid. Thus, in one molecule, the formula (10):

[0049]

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And 90 mol% of a structural unit represented by the following formula (11):

[0051]

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A solution of an organosilicon-modified polyimide compound containing 10 mol% of a structural unit represented by the following formula was obtained. The viscosity of the solution was 8100 cSt.

The solution of the organosilicon-modified polyimide compound obtained above was applied to one surface of a silicon wafer at 2,000 rpm / 30 sec using a spin coater. Next, the silicon wafer was heated at 150 ° C. for 30 minutes, and further heated at 250 ° C. for 1 hour to form a film containing the organosilicon-modified polyimide compound represented by the general formula (7).

The wafer having a film formed on one side as described above is immersed in a mixed solution of 50% hydrofluoric acid (3 volumes) + 40% nitric acid (3 volumes) + acetic acid (4 volumes) for 4 minutes to remove the surface on which the film is not formed. Acid etched. Thereafter, even if the wafer was washed with water and dried, no peeling of the formed film was observed. Next, the washed and dried wafer was immersed in tetrahydrofuran, and washed with an ultrasonic cleaner to dissolve the film. The surface on which the film was formed was protected, and no residue of the formed film was observed.

Comparative Example 1 The amount of γ-butyrolactone was changed from 96 g to 198 g,
36.95 g (0.09 mol) of PP was converted to 40.23.
g (0.098 mol) and the amount of PM 2.49
g (0.01 mol) to 0.50 g (0.002 mo
l) Polyamic was prepared in the same manner as in Example 1 except that
The acid was produced. Next, toluene 3 was added to the polyamic acid.
0 g and heated to 170 ° C.
The acid was dehydrated and ring closed. Thus, in one molecule, the above formula
(8) 98 mol of structural units represented by (see Example 1)
% And the structural unit represented by the formula (9) (see Example 1).
Organosilicon-modified polyimide compound containing 2 mol%
Solution was obtained. The viscosity of the solution was 6700 cSt.
Was. Of the organosilicon-modified polyimide compound obtained above
The solution was applied to one side of a silicon wafer in the same manner as in Example 1.
After coating and film formation, acid etching was performed. afterwards,
The wafer is washed and dried, immersed in tetrahydrofuran,
The film was dissolved and peeled by washing with an ultrasonic cleaner. That
As a result, a part of the wafer surface where the film was formed was etched
Marks were found, indicating that the membrane was unsuitable for the purpose of the present invention.
I understood. Comparative Example 2 The amount of γ-butyrolactone was changed from 96 g to 184 g,
36.95 g (0.09 mol) of PP was added to 24.63.
g (0.06 mol) and the amount of APM is 2.49.
g (0.01 mol) to 9.94 g (0.04 mol)
Except that polyamic acid was used in the same manner as in Example 1.
Manufactured. Next, 30 g of toluene was added to the polyamic acid.
And heated to 170 ° C. to remove the polyamic acid.
The ring was dehydrated. Thus, in one molecule, the above formula
60 mol% of the structural unit represented by (8) and the above formula
Organic containing 40 mol% of the structural unit represented by (9)
A solution of a silicon-modified polyimide compound was obtained. The viscosity of the solution
The degree was 3800 cSt. The organic silicon obtained above
A solution of the elementally modified polyimide compound was prepared in the same manner as in Example 1.
After coating and forming a film on one side of the silicon wafer,
Ching was performed. However, the film does not
It was found that it did not function as a protective film. ratio
Comparative Example 3 Instead of 44.42 g (0.10 mol) of 6FDA
Biphenyltetracarboxylic dianhydride (BPDA) 2
Using 9.4 g (0.10 mol) of γ-butyrolact
N-methyl-2-pyrrolidone 20 instead of 100 g
Using 2 g, the amount of BAPP was 36.95 g (0.09 mol).
l) to 32.84 g (0.08 mol) and A
4.97 g of 2.49 g (0.01 mol) of PM
(0.02 mol), except that it was changed to 0.02 mol.
To produce a polyamic acid. Next, this polyamic
Add 30g of toluene to the acid and heat to 170 ° C before
The polyamic acid was dehydrated and ring closed. Thus, 1
In the molecule, the following formula (21):

Embedded image 80 mol% of a structural unit represented by the following formula (22):

Embedded image Containing 20 mol% of structural units represented by the formula:
A solution of the modified polyimide compound was obtained. The viscosity of the solution is 6
700 cSt. Organosilicon modification obtained above
The solution of the polyimide compound was subsequently prepared in the same manner as in Example 1.
After coating and forming a film on one side of the silicon wafer,
Ching was performed. Then, the wafer is washed and dried, and
Immerse in trahydrofuran and wash with an ultrasonic cleaner
The film was dissolved and peeled. As a result, a film on which a film was formed
Etching marks are observed on part of the EHA surface, and film peeling
The above film is unsuitable for the purpose of the present invention due to residue
I understood.

The circuit protection film of the present invention can prevent circuit damage during acid etching of a semiconductor substrate such as a silicon wafer. Further, since the circuit protective film of the present invention is soluble in some organic solvents, it can be completely removed after the etching treatment.

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Satoshi Toyoda 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Inside Silicone Electronics Materials Research Laboratory, Shin-Etsu Chemical Co., Ltd. (56) References JP-A-63-14452 JP, A) JP-A-59-107524 (JP, A) JP-A-2-180961 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/312 C08G 73/10 C09D 179/08

Claims (1)

(57) [Claims] [Claim 1] General formula (1): [Wherein X is a formula: A tetravalent organic group selected from the group consisting of
Formula: And a divalent organic group selected from the group consisting of And a structural unit (A) represented by the general formula (2): Wherein X is as described above, a plurality of R ¹ may be the same or different, and may be a divalent organic group having 1 to 8 carbon atoms, and a plurality of R ² may be the same or different; 1 atom
And Z is a monovalent organic group represented by the formula: —O—, —CH ₂ CH ₂ —, and And a divalent group selected from the group consisting of And the number of moles m of the structural unit (A) contained in one molecule and the number of moles n of the structural unit (B) contained in one molecule Is a circuit protective film formed on the surface of a semiconductor substrate containing an organosilicon-modified polyimide compound having m / n = 95/5 to 70/30.