JP2000260765A - Pattern formation method of organic insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily form the pattern of a thick organic insulating film on a semiconductor substrate, without prolonging the exposure time of photosensitive resin or breaking a pattern. SOLUTION: In this pattern forming method, after a first photosensitive resin 7 is applied on a semiconductor substrate 1 and is exposed via a photomask 3, a second photosensitive resin 8 is applied on the first photosensitive resin 7 and exposed via the same photomask 3 to form a photosensitive resin of two-layer structure. Then, after unwanted places (photosensitive parts 9, 10) of the first and second photosensitive resins 7, 8 are etched together by an etchant, they are subjected to thermosetting. Thereby, an organic insulating film, which is about twice as thick as a conventional, one can be readily subjected to patterning without prolonging the exposure time of one operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for forming a pattern of a thick organic insulating film on a semiconductor substrate.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become thinner, they are often used in a state where a larger stress is applied to a semiconductor chip, and by forming an elastic organic insulating film on the surface of the semiconductor chip, Attempts have been made to alleviate the stress of the mold resin applied to the semiconductor chip.

Hereinafter, a conventional method for forming a pattern of an organic insulating film will be described. First, an organic resin containing a photosensitive group,
That is, a conventional pattern forming method for forming an organic insulating film using a photosensitive resin will be described with reference to FIG. 2A to 2D are cross-sectional views illustrating a conventional method for forming a pattern of an organic insulating film, wherein 1 is a semiconductor substrate made of silicon or the like, 2 is a photosensitive resin, 3 is a photomask, Denotes a light transmitting portion of the photomask 3, 5 denotes a photosensitive portion of a photosensitive resin, and 6 denotes an opening.

Hereinafter, the manufacturing process will be described in order. First, a photosensitive resin 2 is placed on a semiconductor substrate 1 made of silicon or the like.
(See FIG. 2A). Thereafter, a predetermined area of the photosensitive resin 2 is exposed using the photomask 3 to form a photosensitive portion 5 (see FIG. 2B). Next, the photosensitive portion 5 is etched with a developing solution to perform a developing process for forming an opening 6 in the photosensitive resin 2. At this stage, the opening 6
Is formed to stand upright (FIG. 2 (c)).
See). Thereafter, the photosensitive resin 2 is cured by performing a heat treatment. At this time, the solvent contained in the photosensitive resin 2 volatilizes, and the photosensitive resin 2 shrinks. Then, the thickness of the photosensitive resin 2 after curing becomes about 70 to 80% of that before curing. Shrinkage of the photosensitive resin 2 occurs not only in the thickness direction but also in the lateral direction, and there occurs a phenomenon that the upper layer portion has a large shrinkage while the shrinkage is small near the interface with the semiconductor substrate 1. Then, the opening 6 of the organic insulating film formed by curing the cured photosensitive resin 2 has a tapered shape as shown in FIG.

[0005]

As described above, when a pattern of a thick organic insulating film is formed, the conventional method of forming an organic insulating film is such that the organic insulating film after heat curing has a desired thickness. Then, the photosensitive resin 2 is thickly applied, and the photosensitive resin 2 is directly exposed without using a photoresist. Therefore, it takes 2 to 10 minutes to expose the thick photosensitive resin 2, and there is a problem that the processing time of the exposure process becomes longer. Therefore, the surface of the photosensitive resin 2 is heated by the long-time exposure, the solvent contained in the resin is volatilized, and bubbles are generated in the photosensitive portion 5 to cause a pattern collapse. There is a disadvantage that a serious problem also occurs.

The present invention solves such a conventional problem, and provides a method for patterning a thick organic insulating film without causing pattern collapse.

[0007]

In order to achieve this object, a method for forming a pattern of an organic insulating film according to the present invention comprises applying a first photosensitive resin onto a semiconductor substrate and then pre-baking the first photosensitive resin. A first step of forming a resin layer, and thereafter,
A second step of exposing the first photosensitive resin layer through a photomask, and applying a second photosensitive resin on the first photosensitive resin layer and then pre-baking the second photosensitive resin layer to thereby form a second photosensitive resin layer. A third step of forming a photosensitive resin layer, a fourth step of exposing the second photosensitive resin layer through the photomask, and thereafter, a step of exposing the first photosensitive resin layer and the second A fifth step in which unnecessary portions of the photosensitive resin layer 2 are etched together with a developing solution to leave a predetermined pattern, and thereafter, a heat treatment is performed at a temperature higher than the pre-bake temperature;
And a sixth step of simultaneously curing the patterned first and second photosensitive resin layers.

According to this structure, the first photosensitive resin is applied and exposed on the semiconductor substrate, then the second photosensitive resin is applied and exposed, and then the first and second photosensitive resin layers are formed. To etch with a developer together, the thickness of the photosensitive resin layer, which has been limited by the exposure time and the risk of pattern collapse at one layer, is increased by making the photosensitive resin a two-layer structure. The film thickness can be formed about twice as large as the conventional one.

In a second aspect, the first photosensitive resin is a polyimide resin or a polybenzoxazole resin containing a photosensitive group, and the second photosensitive resin is a polyimide resin or a polybenzoxazole resin containing a photosensitive group. Since the resin is used as a resin, the photosensitive resin in the lower layer and the photosensitive resin in the upper layer are compatible with each other, and a good organic insulating film which does not peel off between layers can be formed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for forming a pattern of an organic insulating film according to the present invention will be described with reference to the drawings.

FIG. 1 is a process sectional view for explaining a method for forming a pattern of an organic insulating film according to an embodiment of the present invention. In FIG. 1, components corresponding to those of the conventional example are denoted by the same reference numerals. 1 is a semiconductor substrate made of silicon or the like, 7 is a polyimide-based resin or polybenzoxazole-based resin containing a first photosensitive group, 3 is a photomask, 4 is a light-transmitting portion of the photomask 3, and 9 is a first photosensitive material. A photosensitive portion exposed to the resin 7, a polyimide resin or a polybenzoxazole-based resin 8 containing a second photosensitive group, a photosensitive portion 10 exposed to the second photosensitive resin 8, and a photosensitive portion 11 formed by development. An opening 12 of the photosensitive resin 7 is an opening of the photosensitive resin 8 formed by development.

Hereinafter, a method for forming a pattern of an organic insulating film having a thickness of about 30 μm will be described as an example in the order of manufacturing steps.
First, the first photosensitive resin 7 is coated on the semiconductor substrate 1 by about 20 μm.
Then, the first photosensitive resin 7 is slightly cured by pre-baking in a temperature range of 100 to 140 ° C. (see FIG. 1A). Next, the photomask 3 is exposed by irradiating light in the direction of the arrow to form a photosensitive portion 9 at a predetermined portion of the first photosensitive resin 7 corresponding to the light transmitting portion 4 of the photomask 3 (FIG. 1 ( b)). After that, the second photosensitive resin 8 is applied on the first photosensitive resin 7 at a film thickness substantially equal to that of the first photosensitive resin (about 20 μm thick), and
Prebaking is performed in a temperature range of 140 ° C. to slightly cure the second photosensitive resin 8 (see FIG. 1C). Next, the photomask 3 is exposed by irradiating light in the direction of the arrow to form a photosensitive portion 10 at a predetermined portion of the second photosensitive resin 8 corresponding to the light transmitting portion 4 of the photomask 3 (FIG. 1 ( d)).
When the resin is heat-cured to finish the organic insulating film, the first photosensitive resin 7 and the first photosensitive resin 7 are considered in consideration that the film thickness of the organic insulating film shrinks to 70 to 80% of the film thickness of the applied resin. The second photosensitive resin 8 is formed to have a total thickness of about 40 μm.

If the pre-bake temperature of the first photosensitive resin 7 and the second photosensitive resin 8 is increased, the adhesion between the first photosensitive resin 7 and the second photosensitive resin 8 becomes poor, and When developing in the process, there arises a problem that the second photosensitive resin 8 is peeled off, and a problem that the sensitivity of the exposing resin becomes low and an opening cannot be made. Conversely, if you lower the pre-bake temperature,
When the second photosensitive resin 8 is applied, the layers of the first photosensitive resin 7 and the second photosensitive resin 8 are broken and mixed with each other, so that the subsequent exposure and development are not performed well. The prebake temperature at which the adhesion was ensured was experimentally determined, and good results were obtained in a temperature range of 100 to 140 ° C.

On the semiconductor substrate 1, a first photosensitive resin 7
After completion of the application, exposure, application of the second photosensitive resin 8 and exposure of the second photosensitive resin 8, the semiconductor substrate 1 is immersed in a developing solution to remove unnecessary portions of the first and second photosensitive resins 7 and 8 ( Photosensitive unit 9,1
The etching process 0) is performed. In this way, the openings 11, 1, and 2 are formed in the first photosensitive resin 7 and the second photosensitive resin 8.
2 (see FIG. 1E). Then 300-40
The first photosensitive resin 7 and the second photosensitive resin 7 are subjected to a heat treatment at 0 ° C.
Are thermally cured together, and the first photosensitive resin 7 and the second photosensitive resin 8 are finally used as an integrated organic insulating film (see FIG. 1F). During the heat treatment, the solvent in the resin volatilizes, and both the first photosensitive resin 7 and the second photosensitive resin 8 shrink, and the organic insulating film after thermosetting has a thickness of 7 to 7 before curing. 80%, and the resin layer having a thickness of 40 μm in total of the first photosensitive resin 7 and the second photosensitive resin 8 is about 3%.
It becomes an organic insulating film of 0 μm.

As described above, in the embodiment of the present invention, after the first photosensitive resin is applied to the semiconductor substrate and processed until the exposure, the second photosensitive resin is applied and exposed. Since the two layers are etched together with a developing solution, an organic insulating film having a thickness approximately twice as large as that of the conventional art can be easily formed by performing the same application and exposure conditions twice as before.

Further, the first photosensitive resin is a polyimide resin or a polybenzoxazole resin containing a photosensitive group, and the second photosensitive resin is a polyimide resin or a polybenzoxazole resin containing a photosensitive group. Since the above resin has a multilayer structure, the first photosensitive resin and the second photosensitive resin are well compatible, and a good organic insulating film from which the upper photosensitive resin does not peel can be formed in a pattern.

Although the above embodiment has been described with reference to a specific example using a photosensitive resin containing a positive photosensitive group, the same applies to the case where a photosensitive resin containing a negative photosensitive group is used. It goes without saying that the same effect can be obtained.

[0018]

As described above, according to the present invention, the first photosensitive resin is applied onto the semiconductor substrate, processed up to the exposure,
After the photosensitive resin is applied and exposed, etching with a developer is performed, so that the same application and exposure conditions are performed twice to easily form an organic insulating film about twice as thick as the conventional one. be able to.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view illustrating a method for forming a pattern of an organic insulating film according to an embodiment of the present invention.

FIG. 2 is a process cross-sectional view for explaining a conventional organic insulating film pattern forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 3 Photomask 4 Transparent part of photomask 3 7 First photosensitive resin 8 Second photosensitive resin 9 Photosensitive part of first photosensitive resin 7 10 Photosensitive part of second photosensitive resin 8 11 opening of first photosensitive resin 7 12 opening of second photosensitive resin 8

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Claims (2)

[Claims] A first step of applying a first photosensitive resin on a semiconductor substrate and then pre-baking to form a first photosensitive resin layer; and thereafter, the first photosensitive resin layer is applied via a photomask. A second step of exposing the photosensitive resin layer, and a third step of applying a second photosensitive resin on the first photosensitive resin layer and then pre-baking to form a second photosensitive resin layer And thereafter, a fourth step of exposing the second photosensitive resin layer through the photomask, and thereafter, removing unnecessary portions of the first photosensitive resin layer and the second photosensitive resin layer. A fifth step of etching together with a developer to leave a predetermined pattern; and thereafter, performing a heat treatment at a temperature higher than the pre-bake temperature to simultaneously cure the patterned first and second photosensitive resin layers. Of the organic insulating film having the sixth step Turn-forming method. 2. The organic insulation according to claim 1, wherein the first photosensitive resin and the second photosensitive resin are a polyimide resin containing a photosensitive group or a polybenzoxazole resin containing a photosensitive group. A method for forming a film pattern.