JP2559614B2 - Method for forming polyimide pattern layer and rinse liquid used in the method - Google Patents

Description

The present invention relates to a method for forming a photocurable polyimide pattern layer on a substrate using a photosensitive polyimide resin, and an interlayer insulating film comprising the polyimide pattern layer. The present invention relates to a rinse liquid having a specific composition used when forming on a substrate.

In the method of the present invention, the photo-curing polyimide pattern layer is excellent in heat resistance, electrical and mechanical properties, and can be formed as a fine pattern layer (film). It can be suitably used for forming a film or a passivation film, or for forming an interlayer insulating film such as a semiconductor integrated circuit or a multilayer printed wiring board.

[Description of Prior Art]

Aromatic polyimide is an organic material suitable for application to electronic parts because of its heat resistance, electrical characteristics, mechanical characteristics, and the like. Furthermore, if photosensitivity is imparted to the aromatic polyimide, it is not necessary to develop and etch the photosensitive resin layer separately for patterning, and the work process can be rationalized. There has been discussion of what to do.

As a method of imparting photosensitivity to the aromatic polyimide,
Since aromatic polyimides are generally poorly soluble in organic solvents,
A method of using a soluble polyimide precursor (aromatic polyamic acid) to impart photosensitivity is known.

For example, JP-A-54-116216 and JP-A-54-1162.
JP-A-54-145794 describes a method for chemically bonding a crosslinkable group to a soluble polyimide precursor described in JP-A No.
JP-A-57-168942 and JP-A-57-168942 include a method of mixing a crosslinkable monomer with an aromatic polyamic acid.

However, in any of the above methods, after photocuring, it is necessary to perform imide ring closure of the polyimide precursor by heat treatment,
At that time, there is a drawback that a loss of film thickness and a decrease in dimensional accuracy are inevitably caused by dehydration accompanying imide ring closure and volume contraction due to volatilization of a crosslinkable group component.

In order to prevent the dimensional accuracy from deteriorating due to the volume shrinkage associated with the imide ring closure, a photosensitive polyimide in which a crosslinkable group is chemically bonded to a soluble polyimide is disclosed in JP-A-58-29821 and JP-A-61-59334. It is proposed in the official gazette.

However, in the photo-cured pattern layer on the substrate obtained by the above-mentioned photosensitive polyimide, the loss of the film thickness and the decrease of the dimensional accuracy are considerably improved, but on the other hand, as shown in FIG. The photo-curing pattern layer of photosensitive polyimide formed as an interlayer insulating film or the like (peripheral portion of the portion 2 where the unexposed portion of the photosensitive polyimide layer is removed by development) is perpendicular to or more than the substrate 1. When a metal thin film processing (wiring processing) is further applied on the wiring 2 for wiring, there is a risk of breaking the wire at the corner of the edge portion of the pattern layer.

Therefore, a method has been used in which the angle of the edge portion of the pattern layer is made obtuse by changing the exposure angle or the like at the time of forming the photocurable polyimide pattern layer, but this is not always sufficient.

[Problems to be solved]

Therefore, an object of the present invention is to provide a method for forming an interlayer insulating film composed of a photocurable polyimide pattern layer having excellent heat resistance and dimensional stability, in which the edge portion of the pattern layer (interlayer insulating film) is a vertical edge. Another object of the present invention is to newly provide a method for easily forming an interlayer insulating film composed of a photo-cured polyimide pattern layer from a photosensitive polyimide layer, which can form an obtuse angle and a smooth edge.

[Means for solving problems]

The first aspect of the present invention is to expose a photosensitive polyimide layer on a substrate to light-cure it in an appropriate pattern and then perform development to remove an unexposed portion with a developing solution. The formed substrate is a rinse liquid for forming an interlayer insulating film, which comprises a photocurable polyimide pattern layer containing at least 5 to 30% by volume of a primary aliphatic amino compound and 2 to 20% by volume of an aprotic basic solvent. And rinsing the substrate, and finally, the substrate having the photo-effect polyimide pattern layer extracted from the rinsing liquid is heat-treated at a high temperature to form an interlayer insulation film composed of a photo-curing polyimide pattern layer. Film (Hereinafter, it may be simply referred to as a pattern layer.)
The second invention is characterized by containing 5 to 30% by volume of a primary aliphatic amino compound and 2 to 20% by volume of an aprotic basic solvent. The present invention relates to a rinse liquid for forming an interlayer insulating film composed of a photocurable polyimide pattern layer.

According to the method for forming an interlayer insulating film comprising a photo-curable polyimide pattern layer of the present invention (hereinafter, also referred to as a pattern forming method), a pattern formed on a substrate 1 as shown in FIG. Since the peripheral portion of the photo-curing layer 2 is inclined with respect to the substrate and the corners are smoothly curved, disconnection of the wiring on the pattern layer occurs when manufacturing a multilayer wiring board. Rarely.

The primary aliphatic amino compound in the rinse liquid used in the pattern forming method of the present invention is a primary organic monoamine compound such as propylamine, butylamine or monoethanolamine, or a primary organic diamine compound such as ethylenediamine or trimethylenediamine. Etc.,
These may be used alone or in combination of two or more.

The proportion of the amino compound used is 5 to 30% by weight, preferably 10 to 25% by volume, based on the total amount of the rinse liquid. If the content of the amino compound is too small, the corners of the pattern edge will be smooth. If the content of the amino compound is too large,
This is not suitable because the thickness of the pattern layer is reduced.

Further, as the aprotic basic solvent in the rinse liquid, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N dimethylacetamide, N, N-diethylacetamide , Hexamethylenephosphoramide, etc.,
These may be used alone or in combination of two or more.

The proportion of the aprotic basic solvent used is 2 to 20% by volume, preferably 5 to 15% by volume. When the content of the aprotic basic solvent is low, the corner of the edge of the pattern layer is Is not a smooth curve, and if the content of the aprotic basic solvent is too large, the dimension of the pattern layer changes, which is not suitable.

In addition, the above rinse solution contains other solvents such as methanol, ethanol, 2-propanol, ethylene glycol, ethyl cellosolve, butyl cellosolve, diethylene glycol, ethyl carbitol, butyl carbitol, acetone, xylene, and non-polyimides such as water. A solvent can be mixed and used.

The photosensitive polyimide used in the pattern forming method of the present invention is preferably a soluble aromatic polyimide having a crosslinkable group.
No. 57620, JP-A-61-156904, at least 30 mol%, preferably 40 mol% or more of an aromatic dicarboxylic acid compound having an aromatic tetracarboxylic acid component and a crosslinkable functional group. The polymer obtained by polymerizing the contained aromatic diamine component in an organic polar solvent is mentioned.

Explaining the photosensitive polyimide in more detail, the aromatic tetracarboxylic acid component used in the production of the photosensitive polyimide, 3,3 ', 4,4'-biphenyltetracarboxylic acid or a dianhydride thereof. , 2,3,3 ′,
4'-biphenyltetracarboxylic acid or its dianhydride,
3,3 ', 4,4'-benzophenone tetracarboxylic acid or a dianhydride thereof, 2,3,3', 4'-benzophenone tetracarboxylic acid or a dianhydride thereof, and the like. An esterification product of tetracarboxylic acid or a salt of the acid may be used, but biphenyltetracarboxylic dianhydride is particularly preferable.

Examples of the aromatic diamine compound used for producing the photosensitive polyimide include, for example, ethyl 3,5-diaminobenzoate (meth) acrylate, 2,4
-Ethyl diaminobenzoate (meth) acrylic acid ester, propylmethacrylic acid 3,5-diaminobenzoic acid methacrylic acid ester, glycidyl 3,5-diaminobenzoic acid (meth) acrylate ester, glycidyl 2,4-diaminobenzoic acid (meth) Benzoic acid esters such as acrylate ester, 3,5-diaminobenzoic acid cinnamic acid ester and 2,4-diaminobenzoic acid cinnamic acid ester, or 3,5
Examples thereof include benzyl acrylate such as -diaminobenzyl (meth) acrylate and 2,4-diaminobenzyl (meth) acrylate.

The aromatic diamine compound used in the production of the photosensitive polyimide may contain the above-mentioned aromatic diamine compound having no crosslinkable functional group.
Examples of the aromatic diamine compound having no such crosslinkable functional group include p-phenylenediamine and m.
-Phenylenediamine, 2,4-diaminotoluene, m-
Xylylenediamine, p-xylylenediamine, 3,5-
Aromatic diamine compounds having one benzene ring such as diaminobenzoic acid, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, m- Aromatic diamine compound having two benzene rings such as diaminodiphenyl sulfone and o-tolidine,
Examples thereof include aromatic diamine compounds having three or more benzene rings such as 1,4-bis (4-aminophenoxy) benzene and 2,2-bis (4-aminophenoxyphenyl) propane.

The above-mentioned photosensitive polyimide has an imidization ratio (the ratio of the number of imide bonds to the total number of bonds capable of forming imide bonds is represented by%) is at least 50% or more, particularly 70% or more, and the logarithmic viscosity is It is preferable that [concentration: 0.5 g / 100 ml (N-methyl-2-pyrrolidone; NMP, measuring temperature; measured at a temperature of 30 ° C.)] is in the range of about 0.05 to 3, particularly 0.1 to 2.

Examples of the photosensitive polyimide include N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-
Methyl-2-pyrrolidone; amide-based solvent such as NMP, or soluble in an organic polar solvent such as dimethyl sulfoxide, diethyl sulfoxide, hexamethylphosphoramide, diglyme, and the organic polar solvent is about 1 to 40 wt. What is necessary is that it dissolves to a concentration of about%.

In the pattern forming method of the present invention, for example, (a) a photosensitive polyimide solution is coated on a substrate by a spin coater or the like, and the solvent is removed from the coating layer under atmospheric pressure or reduced pressure. At a temperature below ℃,
Form a photosensitive polyimide layer (solidified layer), and then (b) expose the photosensitive polyimide layer by irradiating it with an active ray such as ultraviolet ray, visible ray, electron beam or X-ray through an appropriate pattern mask. And photo-curing into an appropriate pattern, and then (c) developing by removing the unexposed portion from the photo-cured polyimide layer by washing off with a developer to form a photo-cured polyimide pattern layer. Is preferred.

The photosensitive polyimide solution contains the photosensitive polyimide in an amount of about 1 to about 1 in the amide solvent, the organic polar solvent, and the like.
It may be dissolved in a concentration of 40% by weight, particularly 2 to 30% by weight.

Further, to the photosensitive polyimide solution, if necessary, a known sensitizer, a photopolymerization initiator and the like can be added, and as such a sensitizer and a photopolymerization initiator, for example, Michler's ketone, benzoin, benzoin ethyl ether, 2-t-butylanthraquinone, 4,4'-bis (diethylamino) benzophenone, benzophenone, thiosanthone, diethylthioxanthone, benzyl and the like can be mentioned, and to enhance its sensitizing effect. , Ethyl N, N-dimethylaminobenzoate, N, N-
It is preferable to add a sensitization aid such as methyl dimethylaminoanthranilate, and further a bisazide compound such as 4,4′-diazidochalcone or 2,6-di- (4′-azidobenzal) -4-methylcyclohexane. Can also be used as a sensitizer.

If necessary, a photopolymerizable compound (monomer) having an ethylenically unsaturated group can be added to the photosensitive polyimide solution.

Examples of the monomer having an unsaturated group include ethylene glycol (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, N, N- Examples thereof include methylenebis (meth) acrylamide, diethylaminoethyl (meth) acrylate, 1,3,5-triacryloylhexahydro-S-triazine, and tris (hydroxyethylacryloyl) isocyanurate.

Further, a thermal polymerization inhibitor, an adhesion aid, etc. can be added to the photosensitive polyimide solution.

As the developer, the above-mentioned amino solvent, a solvent such as cyclohexanone or diethylene glycol dimethyl ether, or a mixed solution of the solvent and methanol, ethanol or the like can be used.

In the pattern forming method of the present invention, the “substrate on which the pattern layer of photocurable polyimide is formed” obtained as described above is used with 5 to 30% by volume of a primary aliphatic amino compound and an aprotic group. The photo-curable polyimide pattern layer on the substrate is rinsed by immersing it in a rinse liquid for forming an interlayer insulating film composed of a photo-curable polyimide pattern layer containing at least 2 to 20% by volume of a basic solvent.

The temperature of the rinse liquid for immersing the substrate is 5 to 50 ° C.,
Particularly preferably 10 to 40 ℃, more preferably 15 to 35 ℃, if the temperature of the rinse liquid is too low, the corners of the edge portion of the photo-curing polyimide pattern layer will not be sufficiently removed, smooth It is not preferable because it may not occur. If the temperature of the rinse liquid is too high, the dimensional accuracy may be deteriorated, which is not preferable.

Further, the time for immersing the substrate in the rinse solution is preferably in the range of 10 seconds to 5 minutes, particularly preferably in the range of 15 seconds to 3 minutes, and when the time is too short, the photocurable polyimide pattern layer This is not preferable because the corners of the edge portion of the above may not be sufficiently removed and may not be smooth, and if the time is too long, the photocurable polyimide pattern layer may be deformed, which is not preferable.

In the pattern forming method of the present invention, after performing the above-mentioned rinsing, finally, the substrate having the photo-curable polyimide pattern layer taken out from the rinse liquid is subjected to a heat treatment at a high temperature to obtain a photo-curable polyimide pattern layer. The inter-layer insulating film (hereinafter, also simply referred to as a pattern layer) made of is formed.

The treatment temperature in the heat treatment is 160 to 250 ° C, preferably about 180 to 230 ° C, and the treatment time is 10 to 250 ° C.
About 60 minutes is preferable in terms of removing the solvent of the rinse liquid contained in the pattern layer.

If the treatment temperature in the above heat treatment is too low, the solvent may remain in the pattern layer or the edge portion of the pattern layer may not be smooth, which is not preferable.

The treatment temperature in the heat treatment is, if necessary,
Temperatures higher than the above processing temperature upper limit (for example, 25
0 to 400 ° C.), and in that case, mechanical properties of the interlayer insulating film (pattern layer) formed of the photocured polyimide pattern layer after the heat treatment may be further improved.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to production examples of the photosensitive polyimide used in the present invention and examples of the present invention.

The angle of the inclined wall in the peripheral portion of the pattern layer was determined by cooling the substrate on which the pattern layer was formed with dry ice and cutting each substrate, and cutting the cut surface with an optical microscope and
It was observed and measured by SEM (scanning electron microscope).

Production Example 1 N-methyl-2-pyrrolidone (NMP) 31.3 ml, 2,3,
3 ', 4'-biphenyltetracarboxylic dianhydride 6.067
g, 3,5-Diaminobenzoic acid ethyl methacrylate ester
3.842 g and m-xylylenediamine 0.843 g were added, and the temperature was 20 ° C.
The mixture was stirred for 24 hours and reacted to obtain a polyamic acid.

Next, after diluting the polyamic acid with NMP153.7 ml, acetic anhydride 41.12 g, pyridine 15.93 g and benzene were added.
30.1 ml was added and reacted at 25 ° C. for 4 hours to obtain a photosensitive polyimide.

The obtained photosensitive polyimide powder is used as the polyimide powder.
When the solution viscosity was measured at 30 ° C. and the logarithmic viscosity was calculated using a 0.5 g / NMP 100 ml solution, the logarithmic viscosity of the photosensitive polyimide was 0.28.

After dissolving 1.00 g of the photosensitive polyimide powder described above in 4.0 g of NMP, 0.08 g of 2,6-di- (4-azidobenzal) -4-methylcyclohexanone was added to prepare a photosensitive polyimide solution (A).

Further, 1.00 g of the above-mentioned photosensitive polyimide powder was dissolved in 5.0 g of NMP, and then 0.045 g of diethylxanthone and 0.068 g of ethyl dimethylaminobenzoate were added to prepare a photosensitive polyimide solution (B).

Example 1 The photosensitive polyimide solution (A) obtained in Production Example 1 was applied onto a glass substrate using a spin coater to form a coating film.
It was dried at 65 ° C. for 30 minutes to form a photosensitive polyimide layer (film).

Then, ultraviolet rays (5 mw / cm ² ) were applied to the photosensitive polyimide layer through a negative pattern of a predetermined shape by a high pressure mercury lamp.
Was irradiated for 40 seconds to expose the photosensitive polyimide layer.

Next, NMP / diglyme / ethanol (mixing volume ratio =
The above-mentioned substrate having the exposed photosensitive polyimide film is dipped in a developing solution composed of a mixed solution of 5: 2: 3) for 2 minutes, and then NMP / monomethanolamine /
The "substrate having the developed photo-curable polyimide pattern layer" was immersed in a rinse solution composed of a mixture solution of isopropyl larucol (mixing volume ratio = 1: 2: 7) for 30 seconds.

Finally, the substrate taken out from the rinse solution was washed with ethanol, and the substrate having the obtained photo-curing polyimide pattern layer was heat-treated at 160 ° C for 30 minutes, and subsequently at 230 ° C for 30 minutes to obtain a clear photocurable polyimide. A patterned layer consisting of

When the pattern layer on the substrate was measured by a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd.), the film thickness was 2.7 μm.
It was m.

When the pattern layer on the substrate was observed with a scanning electron microscope, the edge portion of the pattern layer was not perpendicular to the substrate but was inclined at an angle of about 80 ° with respect to the substrate. The slope was smooth (see Fig. 3).

Example 2 A pattern layer made of photo-cured polyimide was formed in the same manner as in Example 1 except that the substrate was immersed in the rinse liquid for 1 minute.

When the pattern layer on the substrate was measured and observed in the same manner as in Example 1, the film thickness of the pattern layer was 2.7 μm, and the edge portion of the pattern layer was not perpendicular to the substrate, It was inclined at an angle of about 70 ° with respect to the substrate, and its slope was smooth (see Fig. 4).

Example 3 The photosensitive polyimide solution (A) was changed to the photosensitive polyimide solution (B), and ultraviolet rays were irradiated for 200 seconds.
The same procedure as in Example 1 was carried out to obtain a clear pattern layer made of photocurable polyimide.

When the pattern layer on the substrate was measured and observed in the same manner as in Example 1, the film thickness of the pattern layer was 1.0 μm, and the edge portion of the pattern layer was not perpendicular to the substrate, It was inclined at an angle of about 45 ° with respect to the substrate, and its slope was smooth (see Fig. 5).

Comparative Example 1 As a rinsing liquid, a rinsing liquid consisting only of an ethanol liquid (concentration: 100% by weight) was used to rinse the substrate, and a pattern layer made of a photocurable polyimide was prepared in the same manner as in Example 3. It was formed on the substrate.

When the pattern layer on the substrate was measured and observed in the same manner as in Example 1, the film thickness of the pattern layer was 1.0 μm, and the edge portion of the pattern layer was almost perpendicular to the substrate. The vertical surface was not smooth (see Fig. 6).

Comparative Example 2 A pattern layer made of a photo-curable polyimide in the same manner as in Example 3 except that rinsing was performed using a mixed solution of monoethanolamine / isopropyl alcohol (mixing volume ratio = 2: 8) as a rinsing solution. It was formed on the substrate.

When the pattern layer on the substrate was measured and observed in the same manner as in Example 1, the film thickness of the pattern layer was 2.7 μm, and the edge portion of the pattern layer was almost vertical, The vertical surface was not smooth.

Comparative Example 3 A pattern layer made of photo-curable polyimide was prepared in the same manner as in Example 3, except that the rinse liquid was a mixed liquid of NMP / isopropyl alcohol (mixing volume ratio = 1: 9). It was formed on the substrate.

When the pattern layer on the substrate was measured and observed in the same manner as in Example 1, the pattern layer had a film thickness of 2.7 μm and the edge portion of the pattern layer was almost vertical. The vertical surface was not smooth.

[Operation and effect of the present invention]

According to the method of the present invention, if a pattern comprising a photocurable layer of a photosensitive polyimide is formed on a substrate, the patterned photosensitive polyimide photocurable layer formed on the substrate has an appropriate peripheral portion from the substrate. It rises with an inclination (angle of about 30 to 85, especially 40 to 80 ° with respect to the substrate surface), and the corners are rounded (curved with R) and curved, the substrate surface and the pattern Since there is no abrupt step with the layer, even if further wiring is performed on the pattern layer, the wiring does not substantially come into contact with the pattern layer and break, and a multilayer wiring board can be easily manufactured. Is possible.

Further, the rinse liquid of the present invention, by exposing the photosensitive polyimide layer to photo-curing in a pattern, then developing the uncured portion with a developer, and then rinsing the patterned photo-curable layer on the substrate, As described above, the peripheral side wall (wall rising from the substrate) of the patterned photo-curable layer can be given an appropriate inclination and the problematic corner can be eliminated, resulting in a sharp step between the substrate surface and the pattern layer. It has the effect of not forming.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing an example of a state in which a patterned photocurable layer is formed on a substrate by the method of the present invention. FIG. 2 is a cross-sectional view showing an enlarged example of a state in which a patterned photo-curable layer is formed on a substrate by a conventionally known method. 3 to 5 are enlarged views showing the results of observing the edge portion of the pattern layer obtained by the pattern forming method in Examples 1 to 3 of the present invention with a scanning electron microscope. FIG. 6 is an enlarged view showing the result of observing the edge portion of the pattern layer obtained in Comparative Example 1 with a scanning electron microscope.

Claims (2)

(57) [Claims] 1. A photosensitive polyimide layer on a substrate is exposed to light and photo-cured in an appropriate pattern, and then development is carried out by removing an unexposed portion with a developer. The formed substrate,
It is immersed in a rinse liquid for forming an interlayer insulating film comprising a photocurable polyimide pattern layer containing at least 5 to 30% by volume of a primary aliphatic amino compound and 2 to 20% by volume of an aprotic basic solvent, A method for forming an interlayer insulating film comprising a photo-curing polyimide pattern layer, which comprises rinsing the substrate and finally heat-treating the substrate having the photo-curing polyimide pattern layer taken out from the rinsing liquid at a high temperature. 2. A primary aliphatic amino compound in an amount of 5 to 30% by volume
And at least 2 to 20% by volume of an aprotic basic solvent, a rinse liquid for forming an interlayer insulating film comprising a photocurable polyimide pattern layer.