JPH07179604A - Polyimide precursor, polyimide, negative photosensitive material, and method for forming negative pattern - Google Patents

Abstract

PURPOSE:To obtain a polyimide which has low coefficient of linear thermal expansion and elastic modulus and hardly allows interlayer stress to remain when used for a multilayered substrate by converting a polyimide precursor comprising two specific kinds of structural unit into a polyimide. CONSTITUTION:A polyimide precursor comprising structural units of formula I (wherein R1 and R2 are each H, a cation, or an org. group used in esterification provided at least one of them is H; R3 is a lower alkyl group bonded to an arom. ring; m is 0-4; and n is 1-4) and formula II (wherein R1 and R2 are each the same as described above) is converted into a polyimide comprising structural units of formula III (wherein R3, m, and n are each the same as described above) and formula IV by a usual imidizing method such as thermal cyclization or the chemical cyclization using anhydrous pyridine. The obtd. polyimide has low coefficient of linear thermal expansion and elastic modulus and gives, when used for producing a multilayered substrate, a product which hardly causes cracking, interlayer separation, etc., and hardly allows interlayer stress to be accumulated. When the precursor is mixed with a specific 4-(2'-nitrophenyl)-4-hydropyridine deriv. as the photosensitive agent, a negative photosensitive material excellent in resolving power is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polyimide precursor and polyimide, a negative photosensitive material and a negative pattern forming method using the same.

[0002]

2. Description of the Related Art In recent years, a thin film multi-layer substrate (particularly, a copper / polyimide substrate) has been attracting attention for the purpose of high-density mounting of semiconductors and high-speed signal processing. These are subjected to high-temperature heat treatment many times in order to form a multilayer structure by successive lamination operation. However, since the coefficient of linear thermal expansion of a polyimide film generally used as an insulating film is larger than the coefficient of linear thermal expansion of a substrate made of ceramics, glass, silicon, various metals, etc., between the layers of the finally obtained multilayer substrate. Residual stress is accumulated as strain, and as a result, cracks or delamination may occur.

As a countermeasure, a polyimide having a rigid molecular chain structure has been proposed in order to reduce the coefficient of linear thermal expansion of the polyimide. However, although such a polyimide has a low coefficient of linear thermal expansion, it cannot be said to be practically satisfactory as a polyimide used for the above-mentioned applications due to poor adhesion between polyimides. further,
Since such a polyimide has a high elastic modulus, it has an opposite effect for the purpose of reducing the residual stress.

Further, the so-called photosensitive polyimide, which is made to have photosensitivity to the above-mentioned polyimide, is a remarkable technique because it can significantly reduce the number of steps as compared with the step of patterning a non-photosensitive polyimide. Since it generally shows a tendency to become larger, it cannot be said to be practical yet.

[0005]

DISCLOSURE OF THE INVENTION The present invention has solved the above-mentioned problems of conventional polyimides and photosensitive materials using polyimides, and has excellent adhesiveness between polyimides and a thermal linear expansion coefficient and An object of the present invention is to provide a polyimide in which residual stress is unlikely to be accumulated between layers and a polyimide precursor as a precursor thereof even when a multilayer substrate having a small elastic modulus is formed.

Further, another object of the present invention is to provide a negative-type photosensitive material using the above polyimide precursor, a photosensitive substrate using the same, and a negative-type pattern forming method.

[0007]

Means for Solving the Problems As a result of repeated studies on the skeletal structure of polyimide or its precursor, the present inventors have found that 3,3 ', 4,4'- It has been found that the above object can be achieved by using a biphenyltetracarboxylic acid derivative and a paraphenylene diamine capable of substituting an alkyl group as a diamine component, and a fluorinated methyl-substituted benzidine, and completed the present invention.

That is, the first aspect of the present invention is the following general formula (Formula 6).
And a polyimide precursor having a structural unit represented by (Chemical Formula 7).

[0009]

[Chemical 6]

(In the formula, R ₁ and R ₂ are hydrogen atoms or cations, organic groups used in the esterification reaction, and at least one is a hydrogen atom, and R ₃ is bonded to an aromatic ring. It is a lower alkyl group, m is 0 or a positive integer of 4 or less, and n is a positive integer of 4 or less.)

[0011]

[Chemical 7]

(In the formula, R ₁ and R ₂ are hydrogen atoms or cations, organic groups used in the esterification reaction, and at least one is a hydrogen atom.) The second aspect of the present invention The present invention provides a polyimide having a structural unit represented by the following general formulas (Formula 8) and (Formula 9).

[0013]

[Chemical 8]

(In the formula, R ₃ is a lower alkyl group bonded to an aromatic ring, m is 0 or a positive integer of 4 or less, and n is a positive integer of 4 or less. )

[0015]

[Chemical 9]

A third aspect of the present invention is the above-mentioned polyimide precursor and 4- (2 ') represented by the following general formula (Formula 10).
-Nitrophenyl) -4-hydropyridine derivative,

[0017]

[Chemical 10]

(However, in the formula, R_Four And R_Five Is a hydrogen atom
Or an alkyl group having 1 to 3 carbon atoms, R ₆ And R₇ Is charcoal
Alkyl or alkoxyl groups having a prime number of 1 to 4
Lino group, toluidino group, benzyloxy group, amino group,
One selected from dialkylamino groups, R₈ Is a hydrogen atom
Or an alkyl group having 1 to 3 carbon atoms, X₁ ~ X_Four Is
Hydrogen atom, fluorine atom, nitro group, methoxy
Group, dialkylamino group, amino group, cyano group, fluorine
It is a kind selected from the alkylated alkyl groups. In addition, R_FourAnd R₆
 Or R_Five And R₇ Is a 5- or 6-membered ring containing a keto group
Can be a ring or a ring member capable of forming a heterocycle
It ) Is provided as a negative photosensitive material.
To do.

A fourth aspect of the present invention is to provide a photosensitive base material obtained by coating the surface of a supporting base material with the above-mentioned negative photosensitive material.

Further, in the fifth aspect of the present invention, the film obtained from the above negative type photosensitive material is irradiated with an actinic ray through a photomask, and further heat-treated at 170 ° C. or higher to obtain basic The present invention provides a negative pattern forming method, which comprises removing an unexposed portion with a developing solution.

The polyimide precursor having the structural unit represented by the above (Chemical formula 6) or (Chemical formula 7) in the present invention is subjected to a general imidization treatment, for example, a thermal ring closure or a chemical ring closure using anhydrous pyridine. It is converted to a polyimide having the structural units shown in Chemical formulas 8) and 9). The obtained polyimide has properties such that the coefficient of linear thermal expansion and elastic modulus are small after exposure, and the adhesiveness between polyimides is excellent, and stress is unlikely to remain between layers when a multilayer substrate is formed.

Such a polyimide precursor or polyimide of the present invention has a tetracarboxylic acid component of, for example, 3,
3,3 'such as 3'4,4'-biphenyltetracarboxylic dianhydride, 3,3'4,4'-biphenyltetracarboxylic acid halide, and 3,3'4,4'-biphenyltetracarboxylic acid ester The 4,4′-biphenyltetracarboxylic acid derivative can be used for synthesis in an organic solvent such as N-methyl-2-pyrrolidone, dimethylacetamide, dimethylsulfoxide, dimethylformamide, or hexamethylphosphoramide.

As the diamine component, it is necessary to use at least two kinds of diamines, one of which is the aromatic ring such as benzene, biphenyl, triphenyl, terphenyl, toluene, xylene and tolidine. And an aromatic diamine to which R ₃ in (Chemical Formula 8) is bonded. Another diamine component is a fluorinated methylated product of benzidine, which is represented by (Chemical formula 7) or (Chemical formula 9): 1,1′-biphenyl-2,2′-di (trifluoromethyl) -4, 4'-diamine is used. The ratio of the former diamine component to the latter diamine component is 70:30 to 3
It is in the range of 0:70, preferably 55:45 to 45:55. If the amount of the former diamine component is too large, the adhesion between the polyimides becomes poor, and if the amount of the latter diamine component is too large, the coefficient of linear thermal expansion tends to increase, and residual stress tends to accumulate. Incidentally, the polyimide precursor and polyimide of the present invention, as long as it has the above structural unit,
Other tetracarboxylic acid components and diamine components may be used in combination within the range that does not adversely affect the coefficient of linear thermal expansion and elastic modulus.

R ₁ and R ₂ in the above general formulas (Formula 6) and (Formula 7) are hydrogen atoms or cations, organic groups used in the esterification reaction, and at least one of them is a hydrogen atom, and R ₃ Is a lower alkyl group attached to the aromatic ring. Specifically, hydrogen atom, alkali metal ion,
Examples thereof include ammonium ions, alkyl groups having 1 to 3 carbon atoms and fluorinated alkyl groups thereof, benzyl groups, acryl groups, methacryl groups, alkyloxymethyl groups, ter-butoxy groups, and tetrahydropyranyl groups. Of these, preferred are a hydrogen atom, a lower alkyl group and an alkyloxymethyl group. R like this
₁ and R ₂ are ones that are easily eliminated during the imidization reaction to ring the imide.

The photosensitive material of the present invention forms a so-called negative pattern in which the exposed portion remains, and is a polyimide precursor having the structural units shown in (Chemical Formula 6) and (Chemical Formula 7) above. And a 4- (2′-nitrophenyl) -4-hydropyridine derivative represented by the above general formula (Formula 10) as an essential component.

The compound represented by the general formula (Formula 10) is
By irradiating with actinic rays such as ultraviolet rays, the molecular structure changes to a structure having a pyridine skeleton and becomes basic, and a chemical reaction progresses further by the subsequent heat treatment and between the polyimide precursor. Or, by itself, some kind of interaction occurs to lower the alkali solubility, and a difference in solubility between the exposed portion and the unexposed portion occurs, so that a good negative pattern can be obtained.

The above photosensitive compound (Chemical Formula 10) is
It is desirable to add 5 to 70 parts by weight, preferably 15 to 55 parts by weight to 100 parts by weight of the polyimide precursor. When the compounding amount is too small, the dissolution inhibiting ability of the exposed area becomes poor and the solubility contrast tends to become unclear. Also, when the blending amount is large, the solid content is precipitated during storage in the solution state to reduce the solution storability, and the film thickness decreases during the heat treatment after pattern formation, and the mechanical strength also decreases. There is something to do.

Specific examples of the compound suitable as the chemical formula (10) include 2,6-dimethyl-3,5-dicyano-4- (2'-nitrophenyl) -1,4-dihydropyridine, 2 , 6-Dimethyl-3,5-diacetyl-
4- (2'-nitrophenyl) -1,4-dihydropyridine, 2,6-dimethyl-3,5-diacetyl-4-
(2 ′, 4′-Dinitrophenyl) -1,4-dihydropyridine or the like can be used.

The compound represented by the chemical formula (10) is, for example, a reaction of substituted benzaldehyde with 2-fold molar amount of aminocrotonitrile in refluxing glacial acetic acid, or with substituted benzaldehyde and 2-fold molar amount of acetylacetone. It can be obtained by reacting an equimolar amount of ammonia in methanol or by, for example, following a general method for synthesizing a 1,4-dihydropyridine derivative (for example, J. Chem. Soc., 1931 , 1835, 1931 ). Others, West German Publication No. 2003
The methods described in 148 and West German Laid-Open Publication No. 200516 can also be used.

In addition to the photosensitizer represented by the chemical formula (10), a known sensitizer is optionally combined with the negative photosensitive material. Further, the negative photosensitive material of the present invention may contain a dissolution accelerator in order to speed up the dissolution and removal of the unexposed portion by the developer. Although such a dissolution accelerator is completely inactive with respect to the irradiation of actinic rays, it can be made more practical by improving the development rate by containing it.

Examples of such a dissolution accelerator include 2,6-dimethyl-3,5-dicyano-4-methyl-
1,4-dihydropyridine, 2,6-dimethyl-3,
5-dicyano-1,4-dihydropyridine and the like can be mentioned, and it is desirable to add 5 to 50 parts by weight, preferably 5 to 15 parts by weight to 100 parts by weight of the polyimide precursor.

Next, an example of a method for forming a photosensitive substrate and a negative pattern using the photosensitive material of the present invention will be shown below.

First, the polyimide precursor of the present invention,
4- (2′-nitrophenyl) shown in the chemical formula 10
The 4-hydropyridine derivative is dissolved in a suitable organic solvent to prepare a photosensitive solution. Then, this photosensitive solution is dried on a supporting substrate such as a uricone wafer, a ceramic plate, or an aluminum plate to have a film thickness after drying of 1 to 30 μm, preferably 5 to 15
Apply so that the thickness becomes μm.

After the applied coating film is dried (80 ° C., about 10 minutes) to form a photosensitive material, it is exposed to ultraviolet light through a photomask having a desired shape, and after exposure, at 170 to 200 ° C. for about 10 minutes. , Preferably 180
After heating at about 190 ° C. for about 10 minutes, development processing is performed by using a dipping method, a spray method or the like in order to remove an unirradiated portion. The developer used for the development treatment is preferably one that can completely dissolve and remove the unirradiated portion of the exposed film within a suitable time, and an inorganic alkaline aqueous solution such as sodium hydroxide or potassium hydroxide, or propylamine, butylamine, mono An organic alkaline aqueous solution of ethanolamine, tetramethylammonium hydroxide, choline or the like is used alone or in combination of two or more. Also,
If necessary, the alkaline aqueous solution may contain organic solvents such as alcohols and various surfactants.

After development, an image having a desired negative pattern is formed by washing with a rinse solution.

When the image obtained as described above is finally heat-treated at about 200 to 400 ° C., the polyimide precursor, which is a skeletal material, undergoes dehydration ring closure to change into a sparingly soluble polyimide. A negative type image with excellent resolution that does not swell with a liquid or the like is obtained.

[0037]

EXAMPLES The present invention will be described in more detail below by showing Examples of the present invention. The coefficient of linear thermal expansion, elastic modulus, and adhesiveness between polyimide films were measured by the following methods.

<Thermal thermal expansion coefficient> The thermal linear expansion coefficient has a width of 3 m.
m, the distance between chucks is 1 cm, and the temperature rising rate is 10
It was determined by changing the length in the tensile direction while applying a load of 2 g at ° C / min (TMA measurement method).

<Elastic Modulus> A sample having a film thickness of 10 μm, a width of 1 cm, and a distance between chucks of 5 cm was pulled at a pulling speed of 5 mm / min, and the initial gradient of the chart was obtained (tensile elastic modulus).

<Adhesiveness> The operation described in each of the examples and comparative examples was repeated to make the polyimide films adjacent to each other.
Degree of delamination of a film when a polyimide film having a layered structure is prepared and left to stand at 121 ° C. and 2 atm for 100 hours and then a cross-cut test (sample size: 1 cm ² , peeling force: 100 kg / cm ² ) is performed. It was judged by. The case where it was firmly adhered without peeling was marked with ◯, and the case where it was partially or wholly peeled was marked with x.

Example 1 3,3 ', 4,4'-in N-methyl-2-pyrrolidone
Biphenyl tetracarboxylic dianhydride (0.1 mol)
And paraphenylenediamine (0.04 mol), 1,
1′-biphenyl-2,2′-di (trifluoromethyl) -4,4′-diamine (0.06 mol) was reacted for about 48 hours, and R ₁ = H, R ₂ = H, m = 0, A solution of the polyimide precursor having the structural unit represented by the above (Chemical formula 6) in which n = 1 and the above (Chemical formula 7) in which R ₁ = H and R ₂ = H was obtained.

This solution was spin-coated on a glass plate, preliminarily dried at 70 ° C. for 15 minutes, and then heated in a high-temperature heating furnace at 150 ° C., 250 ° C. and 360 ° C. for 1 hour, respectively (Chemical formula 8). A film made of a polyimide having the structural units represented by (Chemical Formula 9) was obtained.

The coefficient of linear thermal expansion (α), elastic modulus (E), and adhesiveness between polyimide films of this film were measured, and the results are shown in Table 1. As is clear from Table 1, an α value of a few dozen ppm, which can be said to be low thermal linear expansion, and an E value of 500 kg / cm ² or less, which can be said to be a low elastic modulus,
The adhesiveness was also good.

Example 2 3,3 ', 4,4'-in N-methyl-2-pyrrolidone
Biphenyl tetracarboxylic dianhydride (0.1 mol)
And paraphenylenediamine (0.055 mol),
1,1'-biphenyl-2,2'-di (trifluoromethyl) -4,4'-diamine (0.045 mol) was added to about 4 parts.
After reacting for 8 hours, R ₁ = H, R ₂ = H, m = 0, n = 1
A solution of the polyimide precursor having the structural unit represented by the above (Chemical Formula 6) and the following (Chemical Formula 7) in which R ₁ = H and R ₂ = H is obtained.

This solution was heated in the same manner as in Example 1 to obtain a film made of polyimide having the structural units shown in (Chemical formula 8) and (Chemical formula 9). The coefficient of linear thermal expansion (α) of this film was The elastic modulus (E) and the adhesiveness between the polyimide films were measured, and the results are shown in Table 1. As is clear from Table 1, the thermal expansion coefficient was low and the elastic modulus was low, and the adhesiveness was also good.

Example 3 3,3 ', 4,4'-in N-methyl-2-pyrrolidone
Biphenyl tetracarboxylic dianhydride (0.1 mol)
And 1,1′-biphenyl-3,3′-dimethyl-4,
4'-diamine (0.04 mol) and 1,1'-biphenyl-2,2'-di (trifluoromethyl) -4,4 '
-React diamine (0.06 mol) for about 48 hours, R
₁ = H, R ₂ = H, R ₃ = CH ₃ , m = 1, n = 2 (Formula 6) and R ₁ = H, R ₂ = H A solution of a polyimide precursor having a structural unit shown below was obtained.

This solution was heated in the same manner as in Example 1 to obtain a film made of polyimide having the structural units shown in (Chemical formula 8) and (Chemical formula 9). The coefficient of linear thermal expansion (α) of this film was The elastic modulus (E) and the adhesiveness between the polyimide films were measured, and the results are shown in Table 1. As is clear from Table 1, the thermal expansion coefficient was low and the elastic modulus was low, and the adhesiveness was also good.

Example 4 3,3 ', 4,4'-in N-methyl-2-pyrrolidone
Biphenyl tetracarboxylic acid (0.1 mol), 1,
1'-biphenyl-2,2'-dimethyl-4,4'-diamine (0.04 mol) and 1,1'-biphenyl-
2,2′-di (trifluoromethyl) -4,4′-diamine (0.06 mol) was reacted for about 48 hours, and R ₁ =
H, R ₂ = H, R ₃ = CH ₃ , m = 1, n = 2 (Formula 6) and R ₁ = H, R ₂ = H (Formula 7)
A solution of a polyimide precursor having a structural unit represented by was obtained.

This solution was heated in the same manner as in Example 1 to obtain a film made of polyimide having the structural units shown in (Chemical formula 8) and (Chemical formula 9). The coefficient of linear thermal expansion (α) of this film was The elastic modulus (E) and the adhesiveness between the polyimide films were measured, and the results are shown in Table 1. As is clear from Table 1, the thermal expansion coefficient was low and the elastic modulus was low, and the adhesiveness was also good.

Example 5 3,3 ', 4,4'-in N-methyl-2-pyrrolidone
Biphenyl tetracarboxylic dianhydride (0.1 mol)
And paraphenylenediamine (0.045 mol),
1,1'-biphenyl-2,2'-di (trifluoromethyl) -4,4'-diamine (0.05 mol) and bis (3-aminopropyl) tetramethyldisiloxane (0.005 mol) For about 48 hours, R ₁ = H,
R ₂ = H, m = 0, n = 1, and R ₁
= H, R ₂ = H, to obtain a solution of the polyimide precursor having the structural unit represented by the chemical formula (7). In addition, bis (3-aminopropyl) tetramethyldisiloxane as a diamine component is a component for improving the adhesiveness to a substrate such as glass or silicon.

This solution was heated in the same manner as in Example 1 to obtain a film made of polyimide having the structural units shown in (Chemical formula 8) and (Chemical formula 9). The coefficient of linear thermal expansion (α) of this film was The elastic modulus (E) and the adhesiveness between the polyimide films were measured, and the results are shown in Table 1. As is clear from Table 1, the thermal expansion coefficient was low and the elastic modulus was low, and the adhesiveness was also good.

Comparative Example 1 1,1'-biphenyl-2,2'- as a diamine component
Without using di (trifluoromethyl) -4,4′-diamine, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (0.1 mol) and paraphenylenediamine (0.1 mol) ) Was the same as in Example 1. (That is, a polyimide film having no structural unit of Chemical formula 7 was prepared.)

The coefficient of linear thermal expansion (α), elastic modulus (E), and adhesiveness between polyimide films of this film were measured, and the results are shown in Table 1. As is clear from Table 1, although it had a low thermal expansion coefficient, it had a high elastic modulus and no adhesiveness between polyimide films.

Comparative Example 2 Paraphenylenediamine was not used as a diamine component,
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (0.1 mol) and 1,1′-biphenyl-2,
The procedure of Example 1 was repeated except that 2'-di (trifluoromethyl) -4,4'-diamine (0.1 mol) was used. (That is, a polyimide film having no structural unit of (Chemical Formula 6) was created.) The coefficient of linear thermal expansion (α), elastic modulus (E), and adhesiveness between polyimide films of this film were measured, and the results were obtained. The results are shown in Table 1. As is clear from Table 1, the elastic modulus was low and the adhesiveness was good, but the thermal linear expansion was high.

Comparative Example 3 Pyromellitic dianhydride (0.1 mol) was used as a tetracarboxylic acid component, and paraphenylenediamine (0.
05 mol) and 1,1'-biphenyl-2,2'-di (trifluoromethyl) -4,4'-diamine (0.0
The same procedure as in Example 1 was carried out except that the reaction was conducted with 5 mol).

The coefficient of linear thermal expansion (α), elastic modulus (E), and adhesiveness between polyimide films of this film were measured, and the results are shown in Table 1. As is clear from Table 1, although it had a low thermal expansion coefficient, it had a high elastic modulus and no adhesiveness between polyimide films.

[0057]

[Table 1]

Example 6 A solution of the polyimide precursor obtained in the same manner as in Example 1 was added with 1.1 times equivalent mole of chloroethyl methyl ether and 1.1 times equivalent mole with respect to the carboxyl group of the precursor. Was added to carry out the esterification reaction at about 0 ° C. for 2 hours.

After completion of the reaction, filtration and reprecipitation with methanol
After treatment with starch and filtration, the precipitate was vacuum dried to obtain polyamide.
An acid esterified product was obtained. This esterified product is R₁ =
-C ₂H_FourOCH₃, R₂ = -C₂H_FourOCH₃, M =
The above (formula 6) where 0, n = 1, and R₁ = -C₂H_FourO
CH₃, R₂ = -C₂H_FourOCH₃The above (Chemical formula 7)
It has a structural unit represented by.

The esterification product of the obtained polyamic acid was added to N
-Methyl-2-pyrrolidone was redissolved, and this solution was heated in the same manner as in Example 1 to prepare a film made of a polyimide having the structural units shown in (Chemical formula 8) and (Chemical formula 9). As a result of measuring the coefficient of linear thermal expansion (α), the elastic modulus (E) and the adhesiveness between the polyimide films, the film showed excellent properties similar to those of Example 1.

Examples 7 to 11 Examples 7 to 11 correspond to Examples 1 to 5, and are shown in Chemical formula 10 as the photosensitizers having the substituents shown in Table 2 in the polyimide precursor solution. 4- (2'-nitrophenyl)
A negative photosensitive material was prepared by adding a -4-hydropyridine derivative.

This photosensitive material was spin-coated on a silicon wafer so as to have a film thickness of about 5 μm, and the film was deposited at 70 ° C. for 15 minutes.
Pre-dry for minutes and then pass through a glass mask for 250
Exposure was performed with a W ultra-high pressure mercury lamp at an energy amount of 300 mJ / cm ² .

After exposure, on a hot plate at 180 ° C. for 3
Negative-type pattern in which only the exposed portion remains on the wafer after heat treatment for 5 minutes, development with a developing solution consisting of tetramethylammonium hydroxide 5% by weight / ethanol (volume ratio 1/1) for about 4 minutes and rinsing with water Got Then
Imidization was carried out by heating at 150 ° C., 250 ° C. and 360 ° C. for 1 hour in a high temperature heating furnace.

The coefficient of linear thermal expansion (α), elastic modulus (E) and the adhesiveness between polyimide films of this imidized film were measured, and the results are shown in Table 2. As is clear from Table 2, α of 10 ppm or more, which can be said to have low thermal linear expansion
And an E value of 500 kg / cm ² or less, which can be said to be a low elastic modulus, and the adhesiveness was also good.

Comparative Examples 4 to 6 Comparative Examples 4 to 6 correspond to Examples 1 to 3 and are shown in Chemical Formula 10 as a photosensitizer having the substituents shown in Table 2 in the polyimide precursor solution. 4- (2'-nitrophenyl)
Negative type patterns were prepared and imidization was performed in the same manner as in Examples 7 to 11 except that the -4-hydropyridine derivative was added.

The coefficient of linear thermal expansion (α), elastic modulus (E), and adhesiveness between polyimide films of this film were measured, and the results are shown in Table 2.

Comparative Example 7 In Example 7, as a photosensitizer, 4 shown in Chemical formula 10
Other than using 2,6-dimethyl-3,5-diacetyl-4- (4'-nitrophenyl) -1,4-dihydropyridine which does not correspond to a-(2'-nitrophenyl) -4-hydropyridine derivative, An attempt was made to form a negative pattern in the same manner as in Example 7, but the pattern was dissolved in the exposed portion and the unexposed portion by the developing solution during development, and the desired negative pattern could not be obtained. .

[0068]

[Table 2]

[0069]

As described above, since the polyimide precursor and the polyimide of the present invention are specific structures having at least two kinds of diamine moieties, they have a small coefficient of linear thermal expansion and elastic modulus and are used for a multilayer substrate. In this case, residual stress between layers is unlikely to be accumulated, and cracks and delamination are unlikely to occur.

Since the photosensitive material of the present invention contains a photosensitizer having a specific structure, a negative pattern having excellent resolution can be obtained by using an alkaline developer instead of a special developer. Can be formed. Therefore, it is possible to form a desired pattern relatively easily and inexpensively as compared with the case of patterning a non-photosensitive polyimide, and it becomes possible to supply a high quality product.
Furthermore, since the final product obtained by high-temperature heat treatment has excellent heat resistance, electrical characteristics, and mechanical specification, it is also suitable as a material for forming a solid element in the semiconductor industry, a protective film for a circuit board, and an insulating film. It is something.

Claims (5)

[Claims] 1. A polyimide precursor having a structural unit represented by the following general formulas (Formula 1) and (Formula 2). [Chemical 1] (Wherein R ₁ and R ₂ are hydrogen atoms or cations, organic groups used in the esterification reaction, and at least one is a hydrogen atom, and R ₃ is a lower alkyl group bonded to an aromatic ring. Further, m is 0 or a positive integer of 4 or less, and n is a positive integer of 4 or less.) (However, in the formula, R ₁ and R ₂ are a hydrogen atom or a cation, an organic group used in the esterification reaction, and at least one is a hydrogen atom.) 2. A polyimide having a structural unit represented by the following general formulas (formula 3) and (formula 4). [Chemical 3] (However, in the formula, R ₃ is a lower alkyl group bonded to the aromatic ring, m is 0 or a positive integer of 4 or less, and n is a positive integer of 4 or less.) 4] 3. The polyimide precursor according to claim 1, and
4- (2'-nitrophene represented by the general formula (Formula 5)
Nyl) -4-hydropyridine derivative, and(However, in the formula, R_Four And R_Five Is hydrogen atom or carbon number
1-3 alkyl groups, R ₆ And R₇ Has 1 to 4 carbon atoms
Alkyl or alkoxyl group, anilino group, tolu
Idino group, benzyloxy group, amino group, dialkyl group
R, a kind selected from mino groups₈ Is hydrogen atom or carbon number
1 to 3 alkyl groups, X₁ ~ X_Four Are each hydrogen
Atom, fluorine atom, nitro group, methoxy group, dialkyl
Amino group, amino group, cyano group, fluorinated alkyl group
It is a kind chosen from. In addition, R_FourAnd R₆ Or R_Five
 And R₇ Is a 5-membered ring containing a keto group, a 6-membered ring, or a heterocycle
Can be a ring member capable of forming a ring. ) Is included
A negative photosensitive material characterized by: 4. A photosensitive base material obtained by coating the negative photosensitive material according to claim 3 on the surface of a support base material. 5. The film obtained from the negative photosensitive material according to claim 3 or 4 is irradiated with an actinic ray through a photomask, and further heat-treated at 170 ° C. or higher to obtain a base. A method for forming a negative pattern, which comprises removing an unexposed portion with a photosensitive developer.