JPH04110348A - Photosensitive polyimide composition and its developing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a method in which a specific aromatic polyimide having a silyloxy group in its side chain and having solubility in an organic solvent is blended with a photosensitive acid generator. A thin film of the composition is formed on a photosensitive polyimide composition and a substrate such as a copper-clad substrate or a silicon wafer, and acid is generated by irradiating it with active energy rays such as light, X-rays, and electron beams. The present invention relates to a developing method in which the polymer in the irradiated area is made into a hydroxylated aromatic polyimide, and the polyimide is dissolved and removed with an alkaline developer to form a patterned aromatic polyimide film on the substrate.

[Description of prior art]

In recent years, a series of new polymers called heat-resistant polymers (such as aromatic polyimides) have been adopted in the field of industrial materials that require heat resistance, chemical resistance, mechanical properties, and excellent electrical insulation properties. It has become. In particular, materials for forming insulating films and passivation films on solid-state devices in the semiconductor industry, and interlayer insulating materials for semiconductor integrated circuits, multilayer printed wiring boards, etc., are required to have high heat resistance and insulation properties. From this point of view, various proposals have been made to form the above-mentioned passivation film etc. with polyimide, which has high insulation properties and high heat resistance.

On the other hand, a heat-resistant photoresist composition (see JP-A-54-109828, etc.) that can be photocured by mixing a monomer having a photocurable group with polyimide soluble in an organic solvent has been proposed. ing.

It has also been proposed to react tetracarboxylic dianhydride with a diamine compound containing a photocrosslinkable unsaturated double bond, such as diaminochalcone, to obtain a polyimide with excellent photosensitivity and heat resistance. (Unexamined Japanese Patent Publication No. 57-1312
(See Publication No. 27).

Furthermore, in recent years, attempts have been made to form relief patterns using solvent-soluble polyimide (see Japanese Patent Laid-Open No. 5829821).

The heat-resistant photoresist composition (Japanese Patent Application Laid-open No. 541098
No. 28) has poor photocurability, and the heat resistance of the polyimide after photocuring is also insufficient.

In addition, aromatic polyimide (Japanese Unexamined Patent Publication No. 5
No. 7-131227) generally has poor solubility in solvents, and therefore is not suitable for forming a pattern that includes a step of dissolving the unexposed areas in an organic solvent after photocuring.

Known photosensitive compositions generally have negative photosensitivity, and positive photosensitive resists are desired for higher resolution, formation of ultrafine line openings, and the like.

In recent years, a positive resist for photosensitive soluble polyimide has been reported in JP-A-64-60630, but in order to use the developed polyimide film as a permanent film, the electrical properties of the film must be In addition, adhesion to the substrate is an important factor, and the above-mentioned positive resists did not fully satisfy these factors.

[Problem to be solved]

In view of the above-mentioned current situation, the inventors of the present application have developed a technology that maintains high levels of heat resistance, moisture absorption resistance, electrical and mechanical properties, as well as the adhesion of the film when formed on a base material. With the aim of providing a soluble aromatic polyimide that maintains its properties for a long period of time even in harsh environments, we have conducted various studies and found that it is photosensitive to an aromatic polyimide that has a large number of silyloxy groups (preferably triethylsilyloxy groups) in its side chains. The present inventors have discovered that a composition containing an acid generator has excellent light transmittance, high photosensitivity, and is soluble in a wide range of organic solvents, achieving the above objectives.

[Means to solve problems]

The first invention of this application is based on the general formula (where A is a tetravalent aromatic residue and B is a silyloxy group or a divalent aromatic residue directly bonded to the aromatic ring). ) 50 mol% or more, preferably 60 mol% or more, particularly preferably 70 to 100 mol% of the repeating unit represented by
Logarithmic viscosity (concentration: 0.5 g/100 mA solvent, solvent: N-methyl-2-pyrrolidone, measurement temperature: 30'C
) is 0.2 to 5, and a photosensitive acid generator.

In addition, a second invention of this application is to form a thin film of the photosensitive polyimide composition on a substrate, irradiate the thin film with active energy rays, generate acid in the irradiated area, and irradiate the irradiated area with an active energy ray. A photosensitive polyimide composition characterized in that a silyloxy group of an aromatic polyimide is changed to a hydroxyl group, and the hydroxylated aromatic polyimide is dissolved and removed with an alkaline developer to form a patterned film on a substrate. Regarding development method.

Below, the photosensitive polyimide composition of the present invention, and
The developing method will be explained in detail.

The soluble aromatic polyimide used in the composition of this invention is a polymer of high molecular weight, e.g.
The logarithmic viscosity (indicating the degree of polymerization of the polymer) measured at a measuring temperature of 30° C. in a polymer solution with a concentration of g/100 m solvent (N-methyl-2-pyrrolidone) is preferably about 0.3 -4, particularly about 0.5 to 3, and the imidization rate measured by infrared absorption spectroscopy is preferably about 90% or more, particularly 95 to 100%.

The soluble aromatic polyimides mentioned above can be used in a wide range of solvents, such as cyclohexanone, chloroporm, dichloromethane, dimethylpolamide (DMF), N-methyl-2
-pyrrolidone (NMP), dimethyl sulfoxide (D
MSO), etc., and has very high storage stability, especially in low hygroscopic solvents such as cyclohexanone and chloroform.

The above-mentioned soluble aromatic polyimide has at least 0.5, especially 0.7 to 4, and more preferably 1 to 3 silyloxy groups (silyl ether groups) per repeating unit in the main chain of the molecule. That's preferable.

The above silyloxy group has the general formula (R) 3S i -0-(II) the general formula (
Any silyloxy group such as RO) 3 S i O(III) (R represents an aromatic group or an alkyl group) is acceptable, such as a trimethylsilyloxy group,
Suitable examples include tri-lower alkylsilyloxy groups such as triethylsilyloxy group and tripropylsilyloxy group, and trialkoxysilyloxy groups such as 1.limethoxysilyloxy group and triethoxysilyloxy group.

Although the aromatic polyimide described above has many silyloxy groups in the aromatic ring such as the benzene ring forming its polymer main chain, the aromatic ring does not substantially contain other functional groups such as hydroxyl groups. It is preferable not to have it from the viewpoint of heat resistance, chemical resistance, etc.

The photosensitive acid generator used in the composition of this invention has an absorption wavelength in the range of 350 to 450 nm, and is preferably irradiated with light at that wavelength or with active energy rays such as X-rays and electron beams. Those that generate Stead acid are preferred, such as: ○ Sulfonic acid ester; R-〇-3-R' (IV) sulfonium salt, R4-3''' , and R to R5 are an alkyl group, an aromatic group such as phenyl, diphenyl, naphthyl, anthryl, and X is a negative ion.

The above-mentioned soluble aromatic polyimide is obtained by polymerizing and imidizing, for example, an aromatic tetracarboxylic acid, its acid anhydride, or its acid derivative, and an aromatic diamine compound in which a hydroxyl group is directly bonded to an aromatic ring. A high molecular weight aromatic polyimide having a hydroxyl group in the side chain is produced, and then silyl chloride is added to a solution of the aromatic polyimide and reacted in the presence of a dehydrochlorination agent to remove the hydroxyl group of the aromatic polyimide. It can be produced by silylation.

The aromatic tetracarboxylic compounds used in the production of the above-mentioned soluble aromatic polyimide include 3,3", 44'- or 2.3.3', 4-biphenyltetracarboxylic acid or its acid dianhydride; or biphenyltetracarboxylic acids such as acid derivatives thereof; benzophenonetetracarboxylic acids such as 3,3°,44'-benzophenonetetracarboxylic acid or its acid dianhydride; or its acid derivatives; 3.3", 4.4 - Preferred examples include "aromatic tetracarboxylic acids having a plurality of benzene rings (especially 2 to 4)" such as biphenyl ether tetracarboxylic acids, their dianhydrides, or acid derivatives thereof. I can do it.

Examples of the above-mentioned "aromatic diamine in which a hydroxyl group is directly bonded to an aromatic ring" include hydroxydiaminobenzenes such as 1-hydroxy-2,5-diaminobenzene and 1-hydroxy-3,5-diaminobenzene; 3.3'
-dihydroxy-4,4°-diaminobiphenyl, 2.
2-dihydroxy-4,4'-diaminobiphenyl, 4
, 4°-dihydroxy-3,3′-diaminobiphenyl and other dihydroxydiaminobiphenyls, 3,3′-
Dihydroxydiaminodiphenyl ethers such as dihydroxy-4,4'-diaminodiphenyl ether, 2,2-dihydroxy-4,4'-diaminodiphenyl ether, 4,4°-dihydroxy-3,3-diaminodiphenyl ether, ■, 4-bis( 3-hydroxy-4
-aminophenoxy)benzene, 1,4-bis(4-hydroxy-3-aminophenoxy)benzene, 1,3-
Bis(hydroxyaminophenoxy)benzenes such as bis(3-hydroxy-4-aminophenoxy)benzene have at least one, especially 1 to 3 hydroxyl groups directly attached to a carbon atom of an aromatic ring such as a benzene ring. Preferred examples include aromatic diamine compound J bonded to .

A preferred example of the method for producing the soluble aromatic polyimide is 3.
．． Aromatic diamine compound A having a hydroxyl group in the benzene ring such as 3'-dihydroxy-4,4'-diaminobiphenyl (HAB) at 50 mol% or more, especially 60 to 100 mol%
Aromatic diamine component containing mol% and biphenyltetracarboxylic dianhydride (BPDA), preferably 2.3.3', 4°-biphenyltetracarboxylic dianhydride (a-BPDA). An aromatic tetracarboxylic acid component containing 50 mol % or more, especially 60 to 100 mol % of aromatic tetracarboxylic acids, and an aromatic tetracarboxylic acid component containing about 50 mol % or more, especially 60 to 100 mol %, in an organic polar solvent at a high temperature (preferably 100 to 300° C., especially about 140° C. A high molecular weight soluble aromatic polyimide (logarithmic viscosity: about 0.2 to 5) is produced by a polymerization reaction and an imidization reaction in a second stage at a high temperature of ~250°C. Alkylsilyl chlorides (
In particular, substantially all of the hydroxyl groups of the polyimide are silylated by adding a silylating agent such as trimethylsilyl chloride, triethylsilyl chloride, triisopropylsilyl chloride, and a dehydrochlorination agent such as imidazole, triethylamine, or pyridine. A method for producing "soluble aromatic polyimide having a large number of groups" can be mentioned.

The soluble aromatic polyimide can be prepared by mixing the two components, the acid component and the diamine component, in approximately equal moles in an organic polar solvent at a low temperature of 80°C or lower (particularly at a low temperature of 0 to 60°C). to produce a high molecular weight aromatic polyamic acid (precursor of aromatic polyimide, logarithmic viscosity: about 0.2 to 5), and then imidize the aromatic polyamic acid under appropriate conditions to make it soluble. An aromatic polyimide is produced, and a silylating agent such as a trialkylsilyl chloride and a dehydrochlorination agent such as imidazole are added to a solution of the polyimide to silylate the hydroxyl groups of the polyimide,
“Soluble aromatic polyimide J containing silyloxy groups can be produced.

Particularly suitable examples of the catalyst include dehydrochlorination agents such as imidazole, and the proportion thereof used is preferably about 1 to 10 moles per mole of the silyl and other agents.

Further, the temperature at which the aromatic polyimide having a hydroxyl group is silylated is preferably about 0 to 60°C.

In addition, in the above-mentioned manufacturing method, the solution produced by the aromatic polyimide having a large number of silyloxy groups is added to a large amount of a lower alcohol such as methanol or ethanol, or a solvent such as water to precipitate the polymer in powder form. filtered,
Furthermore, if necessary, it is preferable to sufficiently wash the product with the above-mentioned lower alcohol and recover it as a purified aromatic polyimide powder.

The above-mentioned silylated soluble aromatic polyimide does not dissolve at all in aqueous alkali solutions such as sodium carbonate and tetramethylammonium hydroxide; Polyimides having a large number of hydroxyl groups in their chains can be easily dissolved in an aqueous alkali solution of about 2%.

The content of the photosensitive acid generator used in the composition of the present invention is 0.01 to 20 parts by weight, preferably 0.05 to 10 parts by weight, per 100 parts by weight of the soluble polyimide.
It is desirable to contain O in parts by weight. If the content of the acid generator is too large, it is not preferable because it has an adverse effect on pattern accuracy.

The composition of the present invention is soluble in organic solvents, and when used in the production of integrated circuits, it is usually used in the form of a solution (resist solution composition). In this case, it is sufficient that the solution composition is dissolved in the above-mentioned organic solvent at a ratio of 1 to 50% by weight, preferably 5 to 30% by weight, and the solution composition has a rotational viscosity of The solution viscosity indicated by is 20 to 10,000 centipoise, especially 50 to 500
It is preferable that the concentration and viscosity be 0 centipoise, and it is preferable that the concentration and viscosity be adjusted to such a value. The solvent used in this case is one that uniformly dissolves the above-mentioned soluble aromatic polyimide, acid generator, etc.
It is preferable that a uniform and smooth coating film can be formed by evaporating the organic solvent after coating on the surface of a substrate such as aluminum. can be used suitably.

In addition to the above-mentioned components, the composition of the present invention may also contain sensitizers, dyes, plasticizers, other resins, thermal reaction inhibitors, various inhibitors, adhesion improvers, etc. as necessary. can do.

A developing method for forming this resist pattern will be described below.

First, a solution of the composition of the present invention prepared as described above is applied to a substrate. This coating onto the substrate can be performed using a spinner, for example. Next, the substrate having the coating film is heated to a temperature of 60 to 160'C1, preferably 80 to 120'C.
Dry for 20-60 minutes at °C to a thickness of about 0.1-50
A thin film of a photosensitive polyimide composition having a thickness of μm is formed.

After drying, the thin film on the substrate is irradiated with active energy rays such as X-rays, electron beams, and ultraviolet rays through a positive photomask chart, and if necessary, the irradiated area is moistened with water using filter paper. 80 to 16
A relief pattern is formed by drying at 0'C for 20 to 60 minutes and washing out the exposed areas with an alkaline developer.

As the alkaline developer, a weak alkaline aqueous solution of sodium hydroxide, potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide or the like having a concentration of 5% by weight or less can be used.

The relief pattern thus formed has good resolution and contrast.

Furthermore, wiring can be formed by etching a substrate such as copper foil using the composition of the present invention and using the pattern formed as described above as a mask.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

Example 1 2.3,3.4-biphenyltetracarboxylic dianhydride (a-BPDA) 6.8 g (23.1 mmo!
, 5.0 g (23,1 mmoA) of 3°3-dihydroxy-4,4°-diaminobiphenyl (HAB), N
-Methyl-2-pyrrolidone (NMP) was added to 400rrl and dissolved at room temperature, filtered through No. 2 filter paper, and the resulting solution was heated and stirred at 180'C in a nitrogen stream for 11 hours to remove the produced water. The NMPlloml containing NMP was flowed out, and polymerization and imidization were performed in one step to produce a soluble aromatic polyimide having hydroxyl groups. After returning the obtained homogeneous polymer solution to room temperature, 6.3 g of imidazole (
92,5 mmoβ) and triisopropylsilyl chloride (92,5 mmoA) were added, stirring was continued for 6 hours at room temperature, and finally methanol 1000
The polymer was precipitated in ml. The obtained polymer powder was further washed with 1000 rrl of methanol and vacuum dried overnight in the presence of phosphorus pentoxide to give 17 g (93% yield).
A powdery white polymer was obtained.

This aromatic polyimide is uniformly dissolved in a wide range of solvents ranging from DMF, NMP, and DMS○ to chloroform and cyclohexanone at a ratio of 10% by weight or more at room temperature, and its logarithmic viscosity (concentration; 0.5 g /
100m7 solvent, solvent, NMP, measurement temperature: 30°C
) was 0.277, and it was a soluble aromatic polyimide having a large number of silyloxy groups (imidization rate: 100%).

The results of thermogravimetric analysis of the aromatic polyimide powder obtained as described above are shown in FIG. 1, and the results of proton NMR of the aromatic polyimide are shown in FIG.

The aromatic polyimide obtained as described above was dissolved in cyclohexanone to prepare a uniform aromatic polyimide solution having a polymer concentration of 10% by weight.

Further, this aromatic polyimide solution was applied onto a glass plate using a doctor knife and dried at about 80'C for 30 minutes and then at 200°C for 30 minutes to form a 7 μm thick aromatic polyimide plate. A thin film was formed.

Regarding this thin film, the light transmittance of light rays with a wavelength of 560 to 200 nm was measured using a self-recording spectrophotometer (manufactured by Kikiguchi Seisakusho, Model 330).
The transmittance of light with a wavelength of nm is 5 to 83% (400
The transmittance of ultraviolet light with a wavelength of 360 nm or less was 2% or less.

Example 2 a-BPDA 4.54 g (15.4 mmo, f7)
,, s-B PDA2.27 g (7.7mm
oβ), HAB5. Og(23,1mmoβ) in NMP
200 m7 and 3 hours at 180°C in a nitrogen stream.
The mixture was heated and stirred, and 25 mA of NMP containing produced water was discharged. After cooling to room temperature, add 6.3 g of imidazole (92
, 5 mmol, and triethylsilyl chloride 1
5.6 ml (92.5 mA) was added and stirred at room temperature for 7 hours.

The resulting homogeneous solution was added to 1,000 rrl of water to precipitate the polymer, which was further washed twice with 1,000 ml of methanol and +2, and dried under vacuum overnight to obtain 14 g of white powder. (Yield: 86.1%) The results of thermogravimetric analysis (TGA) and proton NMR of the obtained polymer are shown in FIGS. 3 and 4, respectively.

Further, in the same manner as in Example 1, a thin film of 8 μm was formed from the above-mentioned soluble aromatic polyimide solution.
As a result of measuring the light transmittance of light with a wavelength of nm, it is 460 ~
The transmittance of light with a wavelength of 560 nm is 75-83% (
30% for light with a wavelength of 400 nm), 360 nm
The transmittance of ultraviolet rays of the following wavelengths was 2% or less.

A 10% by weight cyclohexanone solution of the soluble aromatic polyimide having silyloxy groups obtained as described above was spin-coded onto a substrate at 200 rpm, dried at 80°C, heat-treated at 2000°C for 30 minutes, and then 1 mm thick. 100 outlets were attached at intervals, the sample was treated in a steam stream at 120°C for 20 hours, and a beer peeling test was conducted using adhesive tape. As a result, the residual film rate was 99% or more.

In addition, except for using an NMP solution containing 10% by weight of a soluble aromatic polyimide having hydroxyl groups before silyloxylation,
As a result of conducting the same beer peeling test as mentioned above, the residual film rate was 7.
It was 6%. 0.62 g of the soluble aromatic polyimide having a large number of silyloxy groups obtained as described above;
0.062 g of p-nitrobenzyl-9,10-jethoxyanthracene-2 sulfonate (NBAS) was dissolved in 6.2 g of cyclohexanone, and 0.8
Create a μm coating. This coating film was dried at 150°C for 10 minutes, a thin film of the composition of polyimide and an acid generator was formed on a silicon wafer, a patterned mask was superimposed on the thin film, and the film was heated to a strength of 400 m j / c♂. The light irradiation area was irradiated by exposing it to an ultra-high pressure mercury lamp that irradiated it with light, and then it was covered with a filter paper moistened with water/methanol = 1 and left overnight to moisten the light irradiated area. The silicon wafer with the irradiated thin film was heated at 200°C.
The film is dried for 30 minutes, and then immersed in a 2% aqueous solution of tetramethylammonium hydroxide for 2 minutes to remove the light-irradiated area and developed to form a patterned film. Furthermore, by washing the silicon wafer with the pattern coating formed thereon with water and drying it, it was confirmed that the pattern coating with an interval of 6 μm was clearly formed.

[Actions and effects of the present invention]

Since the composition containing the photosensitive polyimide and the acid generator in this invention uses the aromatic polyimide that has already been imidized, it does not require high heat treatment for imidization, and also does not require electron beam treatment. It is easily possible to create a solubility difference between the irradiated area and the unirradiated area with active energy rays such as X-rays, electromagnetic waves, and ultraviolet rays, and even in this case, no special complicated operations or high temperatures are required. Therefore, development to form a precise pattern can be easily performed.Furthermore, the film of the composition containing the above-mentioned soluble aromatic polyimide (film consisting essentially of polyimide) is It is bonded to the substrate with high adhesiveness due to the large number of silyloxy groups.

[Brief explanation of drawings]

1 and 3 are charts showing the results of thermogravimetric analysis of the polymer, and FIGS. 2 and 4 are charts showing the H-NMR spectrum of the polymer.

Claims (2)

[Claims] (1) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, A is a tetravalent aromatic residue, and B is a divalent aromatic residue with a silyloxy group directly bonded to the aromatic ring. It has 50 mol% or more of the repeating unit represented by ~
A photosensitive polyimide composition characterized in that it contains the soluble aromatic polyimide of No. 5 and a photosensitive acid generator. (2) A thin film of the photosensitive polyimide composition according to claim 1 is formed on a substrate, the thin film is irradiated with active energy rays, and an acid is generated in the irradiated part, so that the aromatic polyimide in the irradiated part is A method for developing a photosensitive polyimide composition, which comprises changing the silyloxy groups of to hydroxy groups, dissolving and removing the hydroxylated aromatic polyimide with an alkaline developer, and forming a patterned film on a substrate.