JP3064579B2 - Pattern formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and more particularly, to a pattern forming method capable of obtaining a fine polyimide film pattern.

[0002]

2. Description of the Related Art In a semiconductor device, a process of providing a protective film (passivation film) on a device surface has been performed for the purpose of protecting the device from the influence of an external environment and improving its reliability. In general, as a material of the protective film, a polyimide resin excellent in electrical properties such as insulating properties and heat resistance is widely used. Polyimide resin is also widely used as an interlayer insulating film in a multilayer wiring structure of a semiconductor device.

The formation of a passivation film or an interlayer insulating film using a polyimide resin as described above is performed, for example, by the following procedure. That is, a varnish of polyamic acid, which is a precursor of the polyimide resin, is applied on a predetermined semiconductor device surface. By subjecting this to heat treatment, thermosetting (imidization) accompanying the cyclization reaction of the polyamic acid occurs, and a polyimide film is formed. Next, a photoresist film is provided on the surface of the polyimide film, and the underlying polyimide film is selectively etched using the photoresist film as an etching-resistant mask, thereby forming a passivation film or interlayer of a polyimide resin having a desired pattern. An insulating film is formed. However, in such a process, it is necessary to perform the formation of the polyimide film and the etching for forming the pattern in two independent steps, which causes a problem of complication of the steps.

[0004] In recent years, many attempts have been made to simplify the above-described steps by using photosensitive polyimide as a photoresist. For example, Japanese Patent Application Laid-Open No. 52-13315 discloses a photosensitive polyimide which can be alkali-developed by utilizing the alkali solubility of polyamic acid and adding a naphthoquinonediazide compound as a dissolution inhibitor thereto. According to the photosensitive polyimide, patterning is performed in a simple process of film formation, exposure, and development.
Can be formed. However, in the developing step, the difference in solubility in the alkali developing solution between the exposed portion and the unexposed portion was not sufficient, and it was difficult to form a fine pattern. Japanese Patent Application Laid-Open No. 62-135824 discloses a process in which such a photosensitive polyimide is formed into a film and then heated to about 90 ° C. before exposure to increase the resolution. Even when applied, the resolution was still insufficient with the photosensitive polyamide as described above.

[0005]

As described above, photosensitive polyimide has been actively developed in recent years, but it has not been possible to obtain a high-resolution pattern by alkali development. .

An object of the present invention is to provide a pattern forming method capable of solving such a problem and realizing a high-resolution polyimide film pattern by alkali development.

[0007]

Means and Action for Solving the Problems The pattern of the present invention
A polyamic acid having a repeating unit represented by the following general formula [1] on a substrate: 1,2-naphthoquinone
Forming a resin layer containing a diazido-4-sulfonic acid derivative as a main component, exposing a desired region of the resin layer, subjecting the exposed resin layer to a heat treatment at 130 to 200 ° C., A negative pattern is obtained by providing a step of developing the resin layer later and a step of heating the developed resin layer to imidize the polyamic acid in the resin layer.

[0008]

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The polyamic acid used in the present invention is not particularly limited as long as it has a repeating unit represented by the general formula [1], and any polyamic acid that can be used for producing a polyimide resin is used. You may. Further, those containing partially esterified polyamic acid units, copolymers of polyamic acid and esterified polyamic acid, and mixtures of polyamic acid and esterified polyamic acid are also acceptable. However, the content of the esterified polyamic acid unit is at most in the polyamic acid.
It is desirably about 70% by weight or less. This is because if it exceeds 70% by weight, the alkali solubility of the polyamic acid may decrease. Further, a preferred polyamic acid and a method of synthesizing the same are described below.

The preferred polyamic acid in the present invention is
Polycondensation of either monoamine [2] or dicarboxylic anhydride [3] represented by the following general formula with tetracarboxylic dianhydride [4] and diamine [5] in the presence of an organic solvent It is synthesized by having

[0011]

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In the above, for example, when the above monoamine [2], tetracarboxylic dianhydride [4] and diamine [5] are used, a polyamic acid represented by the following general formula [6] is synthesized.

[0013]

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When the dicarboxylic anhydride [3], tetracarboxylic dianhydride [4] and diamine [5] are used, a polyamic acid represented by the following general formula [7] is synthesized.

[0015]

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The monoamine represented by the general formula [2] includes m-aminodiphenyl, p-aminodiphenyl, m-aminodiphenyl,
-Aminodiphenyl ether, p-aminodiphenyl ether, aniline, o-anisidine, m-anisidine,
At least one monoamine selected from the group including p-anisidine, p-aminobenzaldehyde, o-toluidine, m-toluidine, and p-toluidine may be used.

The dicarboxylic anhydride represented by the general formula [3] includes phthalic anhydride, hexahydrophthalic anhydride, methylnadic anhydride, 4-methylhexahydrophthalic acid, methyltetrahydrophthalic anhydride, At least one dicarboxylic anhydride selected from the group containing maleic acid may be used.

The tetracarboxylic dianhydride represented by the general formula [4] includes pyromellitic dianhydride, 3,
3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Product, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2- (3 ', 4'-dicarboxyphenyl) propane dianhydride, bis (3,4-
Dicarboxyphenyl) sulfonic anhydride, bis (3,4-dicarboxyphenyl) dimethylsilane dianhydride, bis (3,4-dicarboxyphenyl) tetramethyldisiloxane dianhydride, 1,4,5 At least one tetracarboxylic dianhydride selected from the group including 8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride and butanetetracarboxylic dianhydride Can be used.

The diamines represented by the general formula [5] include m-phenylenediamine, p-phenylenediamine, 2,4-tolylenediamine, 3,3'-diaminodiphenylether, and 4,4'-diamine. Diaminodiphenyl-
Ter, 3,4'-diaminodiphenyl ether, 3,
3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl ketone, 3,
4'-diaminodiphenyl ketone, 2,2'-bis (p
-Aminophenyl) propane, 2,2'-bis (p-aminophenyl) hexafluoropropane, 1,3-bis (p-aminophenoxybenzene), 1,4-bis (p
-Aminophenoxybenzene), 4-methyl-2,4-
Bis (p-aminophenyl) -1-pentene, 1,4-
Bis (α, α′-dimethyl-p-aminobenzyl) benzene, imino-di-p-phenylenediamine, 1,5-
Diaminonaphthalene, 2,6-diaminonaphthalene, 4
-Methyl-2,4-bis (p-aminophenylpentane), 5 (or 6) -amino-1- (p-aminophenyl) -1,3,3-trimethylindane, bis (p-
Aminophenyl) phosphine oxide, 4,4'-diaminoazobenzene, 4,4'-diaminodiphenylurea, 4,4'-bis (p-aminophenoxy) biphenyl, 2,2-bis [p- (p'-amino Phenoxy) phenyl] propane, 2,2-bis [p- (m-aminophenoxy) phenyl] benzophenone, 4,4′-bis (p-aminophenoxy) diphenylsulfone,
4'-bis [p- (α, α-dimethyl-p-aminobenzyl) phenoxy] diphenylsulfonebis (4-aminophenyl) dimethylsilane, bis (4-aminophenyl) tetramethyldisiloxane, bis (p-amino At least one aromatic diamine selected from the group comprising phenyl) tetramethyldisiloxane may be used.

In the above aromatic diamine, the hydrogen atom of the aromatic ring is a chlorine atom, a fluorine atom, a hydrogen atom,
It may be substituted with at least one atom or group selected from the group including a methyl group, a methoxy group and a phenyl group.

The diamine represented by the general formula [5] includes bis (γ) in addition to the above-mentioned aromatic diamine.
-Aminopropyl) tetramethyldisiloxane, 1,4
-Bis (γ-aminopropyldimethylsilyl) benzene, bis (4-aminobutyl) tetramethyldisiloxane, bis (γ-aminopropyl) tetraphenyldisiloxane,

[0022]

Embedded image In some cases, at least one siloxane compound selected from the group including is used. These siloxane compounds are effective in ultimately improving the adhesion between the polyimide film and the substrate, and are preferred diamines in the present invention.

The organic solvents used for the reaction of the above substances include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone,
Methyl-ε-caprolactam, γ-butyrolactone, sulfolane, N, N, N ′, N′-tetramethylurea, hexamethylphosphamide, and the like can be used.

In the synthesis reaction of the polyamic acid using the above substances, the total amount of the monoamine [2] and the amine [5] to be used and the total amount of the dicarboxylic anhydride [3] and the tetracarboxylic dianhydride [4] are determined. The ratio to the total amount is such that the equivalent ratio of the amino group to the acid anhydride group is about 100: 100. The reaction conditions are a reaction temperature of −15 ° C. to 30 ° C. and a reaction time of 10 minutes to 20 hours.

The logarithmic viscosity of the polyamic acid thus synthesized (measured in an N-methyl-2-pyrrolidone solvent at a polymer concentration of 0.5 g / dl at 30 ° C.) is determined based on the coating property of the polyamic acid on a semiconductor substrate. 0.4 to improve
It is desirably 1.0 dl / g, and particularly preferably 0.5 to 0.9 dl / g. In order to adjust the logarithmic viscosity of the polyamic acid to the above range, the usage ratio of each raw material is adjusted as follows.

First, when synthesizing the polyamic acid [6], the monoamine [2] and the diamine [5] are preferably used in a molar ratio of 0.01 to 0.2: 0.9 to 0.995,
0.02 to 0.06: particularly preferably in the range of 0.97 to 0.99. The reason for this is that if the amount of the monoamine [2] is too large, the logarithmic viscosity of the polyamic acid [6] decreases, and it becomes difficult to obtain a smooth film surface when a cured film is formed. Conversely, if the amount of the monoamine [2] is too small, the effect of the molecular terminal treatment of the polyamic acid [6] is small, and workability becomes difficult.

When synthesizing the polyamic acid [7], the molar ratio of the dicarboxylic anhydride [3] to the tetracarboxylic dianhydride [4] is 0.01 to 0.2: 0.
9 to 0.995 is preferable, and 0.02 to 0.06: 0.97 to 0.99
It is particularly preferable if it is in the range of If the amount of the dicarboxylic anhydride [3] is too large, the logarithmic viscosity of the polyamic acid [7] decreases, and it is difficult to obtain a smooth film surface when a cured film is formed. If the amount of [3] is too small, the effect of the molecular terminal treatment of the polyamic acid [7] is small, and workability becomes difficult.

When the siloxane compound is used as the diamine [5], the amount of the siloxane compound used is preferably 0.01 to 20 mol% based on the total amount of amine (monoamine is converted to diamine). Here, if the use amount of the siloxane compound exceeds 20 mol%, the heat resistance of the finally obtained polyamic acid may decrease. If the use amount of the siloxane compound is less than 0.01 mol%, as described above. The effect of improving the adhesion between the polyimide film and the semiconductor substrate cannot be obtained.

On the other hand, it is not particularly restricted but includes naphthoquinonediazide compounds used in the present invention, for example,
1,2-naphthoquinonediazide-4-sulfonic acid, 2,
1-naphthoquinonediazide-4-sulfonic acid and derivatives thereof such as salts, esters, and amides.
Among these, 1,2-naphthoquinonediazide-4-
Sulfonic acid derivatives are preferred, and 1,2-naphthoquinonediazide-4-sulfonic acid ester is particularly preferred. Hereinafter, 1,2-naphthoquinonediazide-4-sulfonic acid ester suitably used in the present invention will be specifically described.

[0030]

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[0031]

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[0032]

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[0033]

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The naphthoquinonediazide compound as described above comprises naphthoquinonediazidesulfonic acid chloride represented by the following structural formula and alcohols, phenol-
The compound can be easily obtained by reacting the compound with an amine or an amine to remove HCl.

[0035]

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In the present invention, the compounding amount of the naphthoquinonediazide compound is 5 to 100 parts by weight of the polyamic acid.
70 parts by weight is preferred, and 25 to 45 parts by weight is more preferred. What is more, if the amount of the naphthoquinonediazide compound is too large, the film thickness during heating in the imide curing step is greatly reduced, and the pattern is impaired. Conversely, if the amount of the naphthoquinonediazide compound is too small, the photosensitivity of the resin layer in the exposure step may be reduced, and the resolution may be reduced. In the present invention, naphthoquinonediazide compound is methyl ethyl ketone, cyclohexane,
It may be blended after being dissolved in an organic solvent such as acetate cellosolve, N, N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphamide.

In the pattern forming method of the present invention, both positive and negative patterns can be formed by selecting the type of the naphthoquinonediazide compound as a photosensitive agent. Although the reason for this is not clear, for example, in the case of using 1,2-naphthoquinonediazide-4-sulfonic acid ester as a photosensitizer, the exposed portion and the unexposed portion are exposed during the exposure and heat treatment steps. Are considered to have caused the following reactions.

That is, in the exposed portion, as shown in the following formula (a), 1,2-naphthoquinonediazide-4-sulfonic acid ester generates indenecarboxylic acid at the same time as the exposure, and And decompose into skeleton parts.

[0039]

Embedded image Further, in the exposed portion, the following reactions (b) to (d) occur during the subsequent heat treatment step. (B) Part of the polyamic acid is imidized due to the involvement of sulfonic acid of indene carboxylic acid generated at the time of exposure. (C) The indene carboxylic acid is decarboxylated to form an indene derivative.

(D) When a polyfunctional 1,2-naphthoquinonediazide-4-sulfonic acid ester is used as a photosensitive agent, unreacted 1,2-naphthoquinonediazide-4-sulfonic acid ester is crosslinked at the time of exposure. . On the other hand, in the unexposed portion, the following reactions (e) and (f) may occur during the heat treatment process. (E) 1,2-naphthoquinonediazide-4-sulfonic acid ester is decomposed by heat to produce indenecarboxylic acid.

(F) When a polyfunctional 1,2-naphthoquinonediazide-4-sulfonic acid ester is used as a photosensitizer, the 1,2-naphthoquinonediazide-4-sulfonic acid ester is crosslinked.

Of the exposed portions, the solubility in an alkali developing solution is increased by the reaction (a),
Conversely, the above reactions (b) to (d) reduce the solubility in an alkali developing solution. For unexposed parts,
The solubility in an alkali developer is increased by the reaction (e), and the solubility in an alkali developer is reduced by the reaction (f). In the pattern forming method of the present invention, a positive pattern is formed when the contribution of the reaction (a) is large, and a negative pattern is formed when the contribution of the reactions (b) to (d) is large. It is considered that a pattern of the mold is formed. Therefore, in the present invention, both positive and negative patterns can be obtained by appropriately selecting the type of 1,2-naphthoquinonediazide-4-sulfonic acid ester as a photosensitizer, and further, exposure conditions and heat treatment conditions. Can be formed. Next, each step of the pattern forming method of the present invention will be described in detail.

First, the polyamic acid and the naphthoquinonediazide compound are dissolved in an appropriate organic solvent, and if necessary, fine impurities are removed by a method such as filtration to prepare a resist solution. Next, the resist liquid is applied on a substrate such as a semiconductor substrate by, for example, a spin coating method, and then dried to form a resin layer according to the present invention.

Next, visible light, infrared light, ultraviolet light, EB, X-ray are applied to the resin layer through a photomask having a desired pattern.
A desired region of the resin layer is exposed by irradiating an energy beam such as a beam. At this time, both exposure methods of contact and projection are possible.

Subsequently, the resin layer is subjected to a heat treatment at a temperature of 130 to 200 ° C. by using, for example, a hot plate, and then left to cool. At this time, if the temperature of the heat treatment is too low, the resolution of the obtained pattern becomes insufficient, and if the temperature of the heat treatment is too high, the solubility of the resin layer in the alkali solution decreases,
Development becomes difficult. A more preferred heat treatment temperature is 140 to 160 ° C. The time for the heat treatment depends on the heat treatment temperature, but is usually preferably about 0.5 to 60 minutes, more preferably about 1 to 5 minutes. If the heat treatment time is too short, the resolution of the resulting pattern will be insufficient, and if the heat treatment time is too long, development of the resin layer will be difficult.

Thereafter, the heat-treated resin layer is developed using an alkaline solution. At this time, the exposed or unexposed portions of the resin layer are dissolved and removed, and a desired positive or negative pattern is formed. As the alkali solution, an organic alkali aqueous solution such as a tetramethylammonium hydroxide aqueous solution or an inorganic alkali aqueous solution such as potassium hydroxide or sodium hydroxide can be used. The development is performed by an immersion method, a spray development method, or the like.

Further, the resin layer on which the desired pattern has been formed by the above-described development is heated at a constant temperature.
As a result, the polyamic acid in the resin layer is ring-closed (imidized), and a polyimide having a repeating unit represented by the general formula [1] is generated. It is preferable that the heating is performed by gradually increasing the temperature from 90 ° C. to 400 ° C. This is because if the temperature rises abruptly during the imidization step, the polyamic acid may remain partially without ring closure, and thermal stability may be impaired.

The polyimide film pattern obtained by the above-described pattern forming method of the present invention exhibits excellent electric insulation and heat resistance, and is suitable as a passivation film or an interlayer insulating film in a semiconductor device. Function. It can also be used as an etching mask in PEP (Photo Engraving Process).

[0049]

The present invention will be described below in detail with reference to examples. Comparative Example 5

A nitrogen gas dried with phosphorus pentoxide was passed through a reaction flask equipped with a stir bar, a thermometer, and a dropping funnel, and 4.635 g (0.21 mol) of pyromellitic dianhydride, 3,3 ', 19.993 g (0.062 mol) of 4,4'-benzophenonetetracarboxylic dianhydride, 0.333 g (0.003 mol) of maleic anhydride and 100 g of N-methyl-2-pyrrolidone were injected. These were sufficiently stirred and mixed, and cooled to -5 ° C.

Next, 15.996 g (0.081 mol) of 4,4'-diaminodiphenyl ether and 1.199 g (0.003 mol) of bis (γ-aminopropyl) tetramethyldisiloxane were added to 69 g of N-methyl-2-pyrrolidone. Dissolve,
This solution was slowly dropped into the reaction flask. The thus obtained mixture was kept at -5 ° C to 0 ° C for 4 hours, and further reacted at room temperature (20 ° C) for 4 hours to synthesize polyamic acid. This polyamic acid / N-methyl-2-
The logarithmic viscosity of the pyrrolidone mixture was measured at 30 ° C. and found to be 0.83 dl / g.

Next, this polyamic acid solution and a naphthoquinonediazide compound represented by the following general formula are weighed so that 10 g of the polyamic acid and 2.5 g of the naphthoquinonediazide compound are blended, and become uniform at room temperature (20 ° C.). And mixed until stirring. This was filtered through a membrane filter having a pore size of 0.5 μm to prepare a resist solution containing a polyamic acid and a naphthoquinonediazide compound as main components.

[0053]

Embedded image With respect to the resist solution prepared as described above, a pattern was formed by the pattern forming method of the present invention, and each characteristic was evaluated. (1) Characteristic test C5- a (resolution evaluation)

The resist solution was coated on a silicon wafer having a diameter of 3 inches by using a spinner and heated on a hot plate at 90 ° C. for 10 minutes to form a resin layer having a thickness of 4.2 μm. did. Next, the surface of the resin layer was exposed through a quartz mask for a resolving power test using a contact exposure machine (CA 800, manufactured by Canon Inc.). At this time, the light irradiation amount is 65 mJ / cm ^{2 at} 365 nm. Met. After exposure, the resin layer
Heat treatment at 150 ° C for 2 minutes, then immerse the silicon wafer together with the resist developer (tetramethylammonium hydroxide, 2.38 wt% aqueous solution) for 60 seconds, and wash with water for 20 seconds to obtain a negative type Pattern was formed.

When the cross section of the pattern was observed with an electron microscope, a line and space of 30 μm were resolved. After this, the obtained pattern was changed to 320
By heating to ℃, good polyimide film pattern
Ngakatachi has been formed. (2) Characteristic test C5- b (adhesion evaluation)

The resist solution was applied on a silicon wafer having a diameter of 3 inches by using a spinner, and this was applied at 90 ° C.
Heated on a hot plate for 10 minutes to a thickness of 5.0μ
m of the resin layer was formed. Next, the temperature of the wafer is sequentially increased in a thermostatic dryer at 150 ° C. for 1 hour, 250 ° C. for 1 hour, and 320 ° C. for 1 hour to imidize the polyamic acid in the resin layer. Was. Further, the wafer is immersed in saturated steam at 2 atm at 120 ° C. for 24 hours.
After heating for an hour, the adhesion was evaluated by the Goban test method. As a result, the resin layer did not peel 100/100, and it was confirmed that the adhesion between the resin layer and the wafer was good. (3) Characteristic test C5- c (heat resistance evaluation)

The resist solution was coated on a silicon wafer having a diameter of 3 inches using a spinner, and heated on a hot plate at 90 ° C. for 10 minutes to form a resin layer having a thickness of 5.0 μm. did. Next, the wafer is placed in a thermostatic dryer at 150 ° C. for 1 hour, at 250 ° C. for 1 hour, at 320 ° C.
, The temperature was sequentially increased for 1 hour to imidize the polyamic acid in the resin layer. After heating, the resin layer was peeled off from the wafer with a razor and measured by thermogravimetric analysis (TGA). As a result, no decrease in weight due to thermal decomposition was observed up to 400 ° C. Comparative Example 1

The same resist solution as in Comparative Example 5 was applied on a silicon wafer having a diameter of 3 inches using a spinner.
This is heated on a hot plate at 90 ° C for 10 minutes,
A resin layer having a thickness of 5.0 μm was formed. Next, the surface of the resin layer was exposed through a quartz mask for a resolving power test using a contact exposure machine (CA800, manufactured by Canon Inc.). At this time, the light irradiation amount was 70 mJ / c at 365 nm.
m ² . Immediately after the exposure, the entire silicon wafer was immersed in a resist developing solution (tetramethylammonium hydroxide, 2.38 wt% aqueous solution) for 60 seconds, whereby the pattern was developed. However, when the silicon wafer was pulled up from the developer and washed with water for 20 seconds, the remaining portion of the resin layer was dissolved, and a good pattern could not be formed. Comparative Example 2

The same resist solution as in Comparative Example 5 was applied to a 3-inch diameter silicon wafer using a spinner.
This is heated on a hot plate at 90 ° C for 10 minutes,
A resin layer having a thickness of 5.0 μm was formed.

Next, the resin layer is subjected to a heat treatment at 150 ° C. for 2 minutes, followed by a contact exposure device (C: manufactured by Canon Inc.).
A 800), the surface of the resin layer was exposed through a quartz mask for resolution test. At this time, the light irradiation amount was 70 mJ / cm ² at 365 nm. After exposure,
The silicon wafer was immediately immersed in a resist developing solution (tetramethylammonium hydroxide, 2.38 wt% aqueous solution) for 60 seconds, but no pattern could be formed. This is considered to be because the naphthoquinonediazide compound in the resin layer was decomposed during the heat treatment before exposure. Comparative Example 6 Examples 1 to 7

Using the raw material composition shown in Table 1, the polyamic acid used in Comparative Example 6 and Examples 1 to 7 was synthesized in the same manner as in Comparative Example 5 (the logarithmic viscosity of the obtained polyamic acid solution was shown in Table 1). 1). Further, the polyamic acid solution and the naphthoquinonediazide compound were mixed in respective predetermined amounts shown in Table 1 to prepare resist solutions of Comparative Example 6 and Examples 1 to 7 . The abbreviations used in Table 1 represent the following acid anhydrides, amines and naphthoquinonediazide compounds, respectively. BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride BTDA: 3,3', 4,4'-benzophenonetetracarboxylic dianhydride PMDA: pyromellitic dianhydride DPE: 4 4'-diaminodiphenyl ether DAM: 4,4'-diaminodiphenylmethane ASi-a: bis (γ-aminopropyl) tetramethyldisiloxane ASi-b:

[0062]

Embedded image A: aniline T: o-toluidine A-a: phthalic anhydride Ab: hexahydrophthalic anhydride Ac: methylnadic anhydride Ad: 4-methylhexahydrophthalic anhydride Ae: maleic anhydride acid

[0063]

Embedded image With respect to the resist solution prepared as described above, a pattern was formed in the same manner as in Comparative Example 5 as described below, and each characteristic was evaluated. (1) Characteristic test C6-a, 1-a to 7-a (resolution evaluation)

With respect to the resist solutions of Comparative Example 6 and Examples 1 to 7 , exposure, heat treatment and development were performed on a silicon wafer in the same manner as in the characteristic test C5- a of Comparative Example 5 to form patterns. . For each of the obtained patterns, the cross section was observed with an electron microscope to measure the resolution, and the results are shown in Table 2. (2) Characteristic test C6-b, 1-b to 7-b (adhesion evaluation)

The resist solutions of Comparative Example 6 and Examples 1 to 7 were evaluated for adhesion to a silicon wafer in the same manner as in the characteristic test C5- b of Comparative Example 5 .
The results are shown in Table 2. (3) Characteristics Test C6-c, 1-c~7- c ( Evaluation of Heat Resistance) Comparative Example 6, with respect to the resist solutions of Examples 1 to 7 and Comparative Examples
The heat resistance on a silicon wafer was evaluated in the same manner as in the characteristic test C5- c of No. 5 . The results are shown in Table 2.

As shown in Table 2, a negative pattern was formed in each case. In particular, the patterns obtained in Examples 1 to 5 had high resolution and showed a close contact between the substrate and the pattern. And heat resistance were also sufficient. In Example 6 , where the amount of the naphthoquinonediazide compound was large, the weight of the resin layer was greatly reduced during imide curing, and the adhesion of the obtained polyimide film to the substrate was also reduced. On the other hand, in Example 7 , in which the amount of the naphthoquinonediazide compound was small, the alkali solubility in the exposed and unexposed areas was relatively large during development, so that the resolution of the obtained pattern was slightly reduced.
It was confirmed that the patterning characteristics were inferior to the others.

[0067]

[Table 1]

[0068]

[Table 2] * Adhesion evaluation (adhesion evaluation): Adhesion with a silicon wafer after heating in saturated steam at 2 atm for 24 hours. * 10% weight loss temperature (° C) (heat resistance evaluation): 320 ° C
Is measured by TGA after heat curing. Examples 8 to 11

The polyamic acids used in Examples 8 to 11 were synthesized using the raw material compositions shown in Table 3 in the same manner as in Comparative Example 5 (the logarithmic viscosities of the obtained polyamic acid solutions are also shown in Table 3). ). Further, the polyamic acid solution and the naphthoquinonediazide compound were mixed in respective predetermined amounts shown in Table 3 to prepare resist solutions of Examples 8 to 11 . still,
The abbreviations newly used in Table 3 represent the naphthoquinonediazide compounds shown below.

[0070]

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With respect to the resist solution prepared as described above, a pattern was formed by the pattern forming method of the present invention as described below, and each characteristic was evaluated in the same manner as in Example 1. (1) Characteristic tests 8-a to 11-a (resolution evaluation)

With respect to the resist solutions of Examples 8 to 11 , the ratio
Exposure, heat treatment, and development were performed on a silicon wafer to form a pattern in the same manner as in the characteristic test C5- a of Comparative Example 5 . However, in this embodiment, the light irradiation amount is 365 n.
m and 150 mJ / cm ^2, and a 1.19 wt% aqueous solution of tetramethylammonium hydroxide was used for development, and the silicon wafer was immersed and further washed with water. As a result, a negative pattern was formed. Each pattern obtained
The resolution was measured by observing the cross section of the film by an electron microscope, and the results are shown in Table 4. (2) Property test 8-b to 11-b (adhesion evaluation)

With respect to the resist solutions of Examples 8 to 11 , the ratio
The adhesion to the silicon wafer was evaluated in the same manner as in the characteristic test C5- b of Comparative Example 5 . The results are shown in Table 4. (3) Characteristic test 8-c to 11-c (heat resistance evaluation)

With respect to the resist solutions of Examples 8 to 11 , the ratio
The heat resistance on a silicon wafer was evaluated in the same manner as in the characteristic test C5- c of Comparative Example 5 . The results are shown in Table 4.

As shown in Table 4, a negative fine pattern was formed in each case, and the adhesion between the substrate and the pattern and the heat resistance were sufficient. In particular, in Examples 8 to 10 , in the adhesion evaluation test, 100/100 peeling did not occur even after heating at 120 ° C for 62 hours, and the adhesion was extremely excellent. In contrast, in Example 11 , 100/100 peeling did not occur after heating at 120 ° C. for 24 hours.
After heating for 62 hours, 10/100 peeling occurred. The reason for this is that when a polyfunctional naphthoquinonediazidesulfonic acid ester is used as a photosensitizer as in Example 11 ,
It is considered that the unreacted naphthoquinonediazidosulfonic acid ester is crosslinked during the heat treatment, so that the flexibility of the resin layer is reduced. Conversely, when a monofunctional naphthoquinonediazidesulfonic acid ester is used as a photosensitizer as in Examples 8 to 10 , particularly excellent adhesion is achieved because the above-described crosslinking cannot occur. I have.

[0076]

[Table 3]

[0077]

[Table 4] * Adhesion evaluation (adhesion evaluation): Adhesion with a silicon wafer after heating in saturated steam at 2 atm for 62 hours. * 10% weight loss temperature (° C) (heat resistance evaluation): 320 ° C
Is measured by TGA after heat curing. Comparative Example 3

[0078] With respect to the resist solution of Example 8, Example 8
A resin layer was formed on a silicon wafer in the same manner as described above. Next, the resin layer was exposed under the same conditions as in Example 8, and immediately immersed in a resist developing solution (a 1.19 wt% aqueous solution of tetramethylammonium hydroxide) for 50 seconds, whereby the pattern was developed. . However, the silicon wafer is pulled out of the developer and further 30
When washed with water for 2 seconds, the remaining portion of the resin layer was dissolved, and a good pattern could not be formed. Examples 12 to 18

Using the raw material compositions shown in Table 5, polyamic acids used in Examples 12 to 18 were synthesized in the same manner as in Comparative Example 5 (the logarithmic viscosities of the obtained polyamic acid solutions are also shown in Table 5). ). Further, the polyamic acid solution and the naphthoquinonediazide compound were mixed in respective predetermined amounts shown in Table 5 to prepare resist solutions of Examples 12 to 18 .
The abbreviations newly used in Table 5 represent the following naphthoquinonediazide compounds.

[0080]

Embedded image

Using the resist solution prepared as described above, a pattern was formed by the pattern forming method of the present invention as described below, and each characteristic was evaluated in the same manner as in Comparative Example 5 . (1) Characteristic test 12-a to 18-a (resolution evaluation)

With respect to the resist solutions of Examples 12 to 18 ,
Exposure, heat treatment, and development were performed on a silicon wafer in the same manner as in the characteristic test C5- a of Comparative Example 5 to obtain a pattern.
Formed. However, in this embodiment, the light irradiation amount is 36.
And 170 mJ / cm ² at 5 nm, development using 1.19Wt% aqueous solution of tetramethyl ammonium hydroxide, silicon wafers - was further washed by immersing, negative type pattern - down is formed. Each pattern obtained
The resolution was measured by observing the cross section of the sample with an electron microscope, and the results are shown in Table 6. (2) Characteristic tests 12-b to 18-b (adhesion evaluation)

With respect to the resist solutions of Examples 12 to 18 ,
The adhesion to the silicon wafer was evaluated in the same manner as in the characteristic test C5- b of Comparative Example 5 . The results are shown in Table 6. (3) Characteristic tests 12-c to 18-c (heat resistance evaluation)

Regarding the resist solutions of Examples 12 to 18 ,
The heat resistance on the silicon wafer was evaluated in the same manner as in the characteristic test C5- c of Comparative Example 5 . The results are shown in Table 6. As shown in Table 6, a negative pattern was formed in each case, and the adhesion between the substrate and the pattern and the heat resistance were sufficient.

In Examples 12 to 18 , although a polyfunctional naphthoquinonediazidesulfonic acid ester was used as a photosensitizing agent, the adhesion was evaluated at 120.degree.
Even after being heated for 100 hours, 100/100 peeling did not occur, and extremely excellent adhesion was obtained. This is because the naphthoquinone diazide sulfonic acid ester used in Examples 12 to 18 has a soft segment such as an aliphatic hydrocarbon structure and a polysiloxane structure in the main chain. This is presumably because, even if crosslinking occurs, the reduction in flexibility of the resin layer is suppressed. That is, when a naphthoquinonediazidosulfonic acid ester having a soft segment such as an aliphatic hydrocarbon structure, a polysiloxane structure, or a polysilane structure in a main chain is used as a photosensitive agent, particularly excellent adhesion can be achieved.

[0086]

[Table 5]

[0087]

[Table 6] * Adhesion evaluation (adhesion evaluation): Adhesion with a silicon wafer after heating in saturated steam at 2 atm for 62 hours. * 10% weight loss temperature (° C) (heat resistance evaluation): 320 ° C
Is measured by TGA after heat curing. Comparative Example 4

With respect to the resist solution of the twelfth embodiment,
A resin layer was formed on a silicon wafer in the same manner as in No. 12 . Next, the resin layer was exposed under the same conditions as in Example 12, and immediately added to a developing solution for resist (a 1.19 wt% aqueous solution of tetramethylammonium hydroxide).
After immersion for 0 seconds, the pattern was developed. However, when the silicon wafer was pulled up from the developer and washed with water for 30 seconds, the remaining portion of the resin layer was dissolved, and a good pattern could not be formed. Examples 19 to 23

The polyamic acids used in Examples 19 to 23 were synthesized using the raw material compositions shown in Table 7 in the same manner as in Comparative Example 5 (the logarithmic viscosities of the obtained polyamic acid solutions are also shown in Table 7). ). Further, the polyamic acid solution and the naphthoquinonediazide compound were mixed in respective predetermined amounts shown in Table 7 to prepare resist solutions of Examples 19 to 23 .
The abbreviations newly used in Table 7 represent the following naphthoquinonediazide compounds.

[0090]

Embedded image With respect to the resist solution prepared as described above, a pattern was formed in the same manner as in Comparative Example 5 as described below, and each characteristic was evaluated. (1) Characteristic tests 19-a to 23-a (resolution evaluation)

Regarding the resist solutions of Examples 19 to 23 ,
Exposure, heat treatment, and development were performed on a silicon wafer in the same manner as in the characteristic test C5- a of Comparative Example 5 to obtain a pattern.
Formed. For each of the obtained patterns, the cross section was observed with an electron microscope to measure the resolution. The results are shown in Table 8. (2) Characteristic tests 19-b to 23-b (adhesion evaluation)

Regarding the resist solutions of Examples 19 to 23,
The adhesion to the silicon wafer was evaluated in the same manner as in the characteristic test C5- b of Comparative Example 5 . The results are shown in Table 8. (3) Characteristic tests 19-c to 23-c (Evaluation of heat resistance) The resist solutions of Examples 19 to 23 were subjected to heat resistance on a silicon wafer in the same manner as in the characteristic test C5- c of Comparative Example 5. Was evaluated. The results are shown in Table 8. As shown in Table 8, in each case, a positive or negative fine pattern was formed, and the adhesion between the substrate and the pattern and the heat resistance were sufficient.

[0093]

[Table 7]

[0094]

[Table 8] * Adhesion evaluation (adhesion evaluation): Adhesion with a silicon wafer after heating in saturated steam at 2 atm for 62 hours. * 10% weight loss temperature (° C) (heat resistance evaluation): 320 ° C
Is measured by TGA after heat curing.

[0095]

As described above in detail, according to the pattern forming method of the present invention, it is possible to form a pattern with high resolution by alkali development, so that a fine pattern having excellent adhesion and heat resistance can be obtained. A polyimide film pattern can be simply realized, and its industrial value is great.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 21/312 H01L 21/30 502R (72) Inventor Yoshihiko Nakano 1 Kosuka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa TOSHIBA CORPORATION (56) References JP-A-62-135824 (JP, A) JP-A-4-120171 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 7/022 G03F 7/037 G03F 7/038 G03F 7/38 H01L 21/027 H01L 21/312

Claims (1)

(57) [Claims] 1. A polyamic acid having a repeating unit represented by the following general formula [1] on a substrate: 1,2-naphthoquinone
Forming a resin layer containing a diazido-4-sulfonic acid derivative as a main component, exposing a desired region of the resin layer, subjecting the exposed resin layer to a heat treatment at 130 to 200 ° C., A pattern forming method comprising a step of developing the resin layer and a step of heating the developed resin layer to imidize the polyamic acid in the resin layer to obtain a negative pattern.