JPS63143847A - Laminated structure - Google Patents

Abstract

PURPOSE:To improve the reliability of an element without remnant on the surface of a substrate, by laminating a polyimide layer A, which does not include colloidal silica and a polyimide layer B including the colloidal silica on the substrate, and obtaining a laminated structure, in which both polyimides are patterned at the same time. CONSTITUTION:A film A is formed on a substrate. The film is usually formed by applying the solution of the presursor of polyimide. A film B comprising polyimide including colloidal silica is formed on the film A. The film B is formed by applying the solution of the precursor of polyimide, in which a specified amount of colloidal silica is added, on the film A as the formation of the film A. Thus a laminated body of the film A and the film B is obtained. When the precursor of the polyimide having light sensitivity is used as the polyimide, application and drying are repeated. The laminated film of the layer A and the layer B are formed. A mask is placed thereon, and the layers A and B are exposed at the same time. The layers A and B are developed at the same time. After a pattern is formed, heat treatment is performed. Then the laminated structure having a relief groove is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminate structure, and more particularly, to a laminate structure having a relief structure consisting of a polyimide layer and a colloidal silica-containing polyimide layer. be.

[Prior Art] Polyimide has excellent properties such as heat resistance, electrical insulation, and the ability to form patterns, and is widely used in the semiconductor industry, such as as a protective film for semiconductor elements and as an insulating film for living rooms. However, it has several drawbacks, including poor chemical resistance to alkalis and inorganic acids. Alkali and inorganic acids are used as etching agents for substrates (silicon) and metal wiring. By improving resistance to these, the selection of etching agents will become wider.
It also has the advantage of being able to measure process stability.

On the other hand, when we used the colloidal silica-containing polyimide previously proposed by the present inventors, we found that it showed good resistance to these chemicals, but in order to improve the chemical resistance, the amount of colloidal silica added was When increasing the amount, we encountered the problem that colloidal deer residue remained on the substrate surface during pattern formation.

If such residue remains, for example, on the wiring metal of the element, it will cause a decrease in reliability such as poor conduction with external terminals.

[Problems to be Solved by the Invention] An object of the present invention is to solve these problems and provide a laminated structure having a high reliability and a good relief structure.

[Means for Solving the Problems] The object of the present invention is to provide a laminate structure in which a polyimide layer (A>) and a polyimide layer (B) containing colloidal silica are laminated in this order on a substrate. , both polyimide layers are simultaneously patterned to provide a laminate structure with a relief structure.

Examples of the substrate in the present invention include silicon wafers and glass.

The polyimide as used in the present invention is a polymer containing the general formula (in the formula, R1 is a tetravalent Ti group and R2 is a divalent Il group) as a main structural unit. The structural unit [
1] may include units other than 1].

Amidimide as a unit other than the structural unit [I].

Examples include, but are not limited to, esterimides, isoindoquinazoline rings, and the like.

In the above structural unit [I], R1 is a tetravalent organic group having at least two or more carbon atoms. In view of the heat resistance of the polyimide, R1 preferably has a structure in which the bond to the carbonyl group of the polymer main chain is directly formed through an aromatic ring or an aromatic heterocycle. Therefore, R1 contains an aromatic ring or an aromatic heterocycle and has 6 to 3 carbon atoms.
A tetravalent group of 0 is preferred.

In the above structural unit [I], R2 is a divalent organic group having at least two or more carbon atoms, but from the viewpoint of heat resistance of polyimide, the bond with the imide group of the main chain of the polymer is an aromatic ring or Those having a tpi structure directly formed from an aromatic heterocycle are preferred. Therefore, R2 is preferably a divalent group containing an aromatic ring or an aromatic heterocycle and having 6 to 30 carbon atoms.

Furthermore, in order to improve the adhesiveness of polyimide, it is also possible to copolymerize an aliphatic group having a siloxane structure as R2 within a range that does not reduce heat resistance.

Preferred specific examples include, but are not limited to, the following.

In the structural unit [11], each of R1 and R2 may be composed of only one type, or may be composed of two or more types.

Specific examples of polyimides include, but are not limited to, polyimides obtained by chemically or thermally converting polyimide precursors obtained from the following combinations.

3.3°,4,4°-benzophenonetetracarboxylic anhydride (BTDA) and 4,4°-diaminodiphenyl ether (ODA>).

3.3',4,4°-biphenyltetracarboxylic anhydride (BPDA> and ODA.

Viromelli 1-acid anhydride (PMDA) (50 mol%),
BTDA (50 mol%) and ODA (100 mol%).

BPDA (50 mol%>, BTDA (50 mol%)
and 0DA (100 mol%).

BTDA and 3.3'-(or 4.4'-)diaminodiphenylsulfone (DDS).

PMOA and ODA.

BPDA and p-phenylenediamine (PPD).

PMDA and 3,3°-dimethylbendine (DMB) B
PDA and DMB.

BPDA and p-tolylenediamine (PTD).

PMOA and PTD.

PMDA and 3,3°-dimethoxybendine.

PMDA and 4,4° diaminofluorene (DAF).

BPDA and DAF.

BTDA and DAF.

PMOA (50 mol%>, BTDA (50 mol%)
and DDS (100%).

BPDA and DDS.

PMDA (50 mol%), [3TDA (50 mol%
>, ODA (85%) and 4,4°-diaminodiphenyl ether-3-carbonamide.

BTDA and 4,4'-diaminodiphenylmethane.

Also, combinations of each of these with bis(3-7minoprobyl)tetramethyldisiloxane are particularly preferred. Here, the blending ratio of bis(3-aminopropyl)tetramethyldisiloxane is preferably 1 to 15 mol% of the total amine, more preferably 3 to 6 mol%. In the present invention, colloidal silica is It is a colloidal solution of high molecular weight silicic anhydride. These include those prepared from water glass and those prepared from alkyl silicate or chlorosilane, etc., and either of them can be used.

Those prepared from water glass are commercially available as silica sol. The dispersion medium is usually water, but those dispersed in organic solvents are also commercially available (for example, 03CAL from Catalysts & Chemicals Co., Ltd.).

Those prepared using chlorosilane, an alkyl silicate, as a raw material can be obtained, for example, by hydrolysis with ammonia water in methanol.

Polyimides are typically prepared as solutions of precursors. Therefore, dimethylformamide, dimethylacetamide, N-methyl-
Colloidal silica dispersed in an aprotic polar solvent such as 2-pyrrolidone (NMP) is preferred from the viewpoint of compatibility.

Colloidal silica dispersed in these aprotic polar solvents can be obtained by replacing the dispersion medium with a method such as distillation. For example, if NMP is added to colloidal silica dispersed in methanol and the methanol is distilled off, the NMP
A product dispersed in MP is obtained.

Addition amount of colloidal silica 3 (wt%) is 0°5 to 4
The range is preferably 5 (wt%), more preferably 2 to 4
0 (wt%) is good. In addition, the addition of colloidal silica
s (wt%) is given by the following formula.

Si02 ffi (g) S (wt%) = X 10
Amount of 0Si02+Amount of polyimide (g) If less than the lower limit amount is added, the effect of improving properties will not be significant, and if more than the upper limit amount is added, pattern workability will deteriorate.

Polyimide with added colloidal silica is produced by adding colloidal silica dispersed in an aprotic polar solvent to a solution of a polyide precursor (in the case of soluble polyimide, a solution of imidized polymer), applying the mixed solution, and heat-treating. It can be obtained by

In this case, it is more preferable to add a tertiary amine compound to the solution because the colloidal silica is uniformly dispersed in the film. Preferred tertiary amines include dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, triethylamine, and the like.

A laminated structure of membrane (A> and membrane (B), where membrane (A) and membrane (B)
) There is no particular restriction on the ratio of the film thickness of the film (A>), but the thickness of the film (A>) is preferably 0.5 μm or more, more preferably 1 μm.
It is better to set it to the above.

Next, an example of a method for manufacturing the laminated structure of the present invention will be described.

First, IIH(A) is formed on a substrate. The membrane (A) is
Usually, a film is formed by applying a solution of a precursor of the polyimide (in the case of soluble polyimide, a solution of an imidized polymer).

Next, a film (B) made of polyimide containing colloidal silica is formed on the film (A). Film (B) is formed by similarly applying a solution of a polyimide precursor to which a predetermined amount of colloidal silica has been added onto film (A). A laminate is made 19.

The patterning of the layered structure with Ill (A> and film (B)) can be done in several ways.

When using a photosensitive polyimide precursor as the polyimide, coating and drying are repeated to form layers (A) and (B).
) After forming a laminated film of layers, a mask is placed on top of this, and (A>
, (B) layers are exposed simultaneously. Then, (A>, (B)
If the layers are developed simultaneously and heat treated after forming the pattern,
A laminated structure with a relief structure according to the invention is obtained.

When using a polyimide precursor that does not have photosensitivity, it is coated, dried, and coated with a positive photoresist, followed by irradiation with ultraviolet rays through a mask. Next, the photoresist is developed with a positive photoresist developer and the film (III) (A>, film (
B) Etching is performed at the same time. After peeling off the photoresist film, a heat treatment is performed to obtain a laminated structure having a relief structure. Alternatively, etching may be performed using a mixed solution of hydrazine and ethylenediamine using a negative photoresist as a mask.

The heat treatment is carried out for 5 minutes to 5 hours by selecting several temperatures in the range from room temperature to 450° C. and increasing the temperature stepwise, or by selecting a certain temperature range and increasing the temperature continuously. The maximum temperature of this heat treatment is 150-450°C, preferably 180-250°C.
It is best to do this at ℃.

For example, heat treatment is performed at 130° C. and 200° C. for 30 minutes each. Alternatively, the temperature may be increased almost linearly from room temperature to 400° C. over 2 hours.

The laminated structure of the present invention obtained in this way is a protective film for semiconductor elements, a protective film for soldering of circuits from pudding 1, and a protective film for soldering of circuits.
It is used as a protective film for O-cystars and as an interlayer insulating film for multilayer integrated circuits.

[Effects of the Invention] The present invention provides a laminated structure in which a polyimide layer (A) not containing colloidal silica and a polyimide layer (B) containing colloidal silica are laminated in this order on a substrate, and both polyimides are patterned simultaneously. Since no residue remains on the substrate surface, the reliability of the device is significantly improved6.

[Example] The present invention will be explained based on examples.

Example 1 4.4°-diaminodiphenyl ether 56.45 g,
4.47 CJ of bis(3-aminopropyl)tetramethyldisiloxane was dissolved in 520 g of tomethyl-2-pyrrolidone to prepare an amine solution. Adding 96.70% of benzophenone tetracarboxylic dianhydride to this amine solution,
The reaction was carried out at 50°C for 3 hours to obtain a polymer solution (I) of 150 poise at 25°C.

To this polymer solution <I), 94.3 g of dimethylaminoethyl methacrylate, 4°0 g of Michler's ketone, and 100 g of tomethyl-2-pyrrolidone were added and mixed, and filtered to prepare a photosensitive polyimide precursor coating solution (I). did.

Separately, add 94.3 q of dimethylamine ethyl methacrylate, 4.0 q of Michler's ketone, and 100 q of N-methyl-2-pyrrolidone to the newly prepared polymer solution (I).
g and tomethyl-2-pyrrolidone and colloidal silica (Catalyst Chemical Industry Co., Ltd. 1 trade name 03CAL) was dispersed in 3 g and tomethyl-2-pyrrolidone.
Coating solution of colloidal silica-containing polyimide precursor having photosensitivity by adding 5 wt%, mixing, and r-filtering (I[I)
It was created.

Coating solution (U>) was applied with a spinner onto the silicon wafer on which the elements were formed so that the film thickness was 5μ, and heated at 80°C.
It was dried for 1 hour. Further, coating liquid (I[) was applied thereon to a coating thickness of 15 μm, and then dried at 80° C. for 1 hour to create a laminated structure having layers (A) and (B).

Next, this was set in an exposure machine, and layers (A) and (B) were simultaneously exposed at 3001 nJ/cnf (3001 nJ/cnf) through a chrome mask.
65 stops) exposed. Development was carried out using a mixed solvent of N-methyl-2-pyrrolidone (70 parts) and methanol (30 parts).
The immersion method was used while applying ultrasonic waves. (A), (
B) After developing the layers simultaneously, rinse with isopropanol,
Dry with a spinner.

Next, heat treatment was performed continuously in nitrogen at 135, 200, 300, and 400 ("C) for 30 minutes each.

In this way, by patterning the (A> layer and (B) layer) at the same time, we were able to obtain a laminated structure with a good relief structure without any residue on the substrate. Also, conduction with external terminals was also good. Met.

Comparative Example 1 On the same silicon wafer as in Example 1, the coating liquid (II) was applied with a spinner so that the coating film thickness was 5 μm.
It was dried at ℃ for 1 hour. Next, in the same manner as in Example 1, a pattern of only the layer (A) was formed on the substrate by exposure, development, and heat treatment. Further, coating liquid (1) was applied on top of this so that the coating thickness was 15 μm, and after drying at 80°C for 1 hour, exposure, development, and heat treatment were performed in the same manner as above (on the pattern of A> layer). A pattern of the layer (B) was formed.

Visual observation of the substrate surface of the laminated structure having the relief structure obtained by patterning the (A> and (B) layers separately) revealed that the white colloidal silica residue was not removed and was deposited. The connection with the external terminal was poor.

Claims (1)

[Claims] A laminated structure in which a polyimide layer (A) and a polyimide layer (B) containing colloidal silica are laminated in this order on a substrate, and both polyimide layers are simultaneously patterned to have an embossed structure. A laminated structure.