JPH05136298A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a cost by reduction of the number of processes, to improve yield and to improve production efficiency by forming a recessed part for improving adhesion between a mold resin body and a protecting film simultaneously with shaping of a pad part which becomes an electrode lead-out part by using resolution defective. CONSTITUTION:A PSG film 3 is formed all over a semiconductor substrate 1. An aluminum electrode 2 is exposed and a polyimide 4 is formed. After a resist 5 is applied, exposure and development are carried out by contact exposure method by using a mask having a pattern 21 for exposing the aluminum electrode 2 and a two-by-two mum square pattern 22. In the process, resolution of the pattern 22 is defective and the resist 5 at a part corresponding to a pattern 25 is not completely exposed and a recessed part 6 is formed on a surface of the resist 5. When the polyimide 4 is etched using the resist 5 as a mask, the polyimide 4 corresponding to the recessed part 6 is slightly etched and a recessed part 7 is formed simultaneously with exposure of an aluminum electrode 2. Therefore, the number of processes is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of patterning a surface protective film of a semiconductor element.

[0002]

2. Description of the Related Art On the surface of a semiconductor substrate having a semiconductor element formed thereon, a plasma nitride film or PSG (Phospho-Silicate G
A protective film made of an inorganic material such as (lass) is formed. The semiconductor chip thus formed is bonded to a lead frame and then sealed with a mold resin body such as an epoxy resin. In recent years, a method has been adopted in which an organic polymer film such as polyimide is formed as a buffer coating film on the protective film made of an inorganic material in order to relax the stress of the mold resin on the semiconductor chip.

However, since the protective film made of an organic polymer material has poor adhesion to the mold resin, when a shock such as a thermal shock is applied, a gap is formed between the semiconductor chip and the mold resin body. May occur. When this void is formed, a large amount of moisture that has entered from the outside is accumulated in this void. If the impurity ions dissolved from the mold resin body dissolve in this water, it becomes a factor that corrodes the electrode made of aluminum or the like. Further, since a large amount of accumulated water repeatedly expands and contracts due to heat change, this stress also causes a crack (crack) in the mold resin body.

In order to solve this drawback, for example, a part or the whole of the boundary between the protective film made of an organic polymer material and the mold resin body is formed by a surface having a large number of irregularities so that it is sufficiently resistant to thermal shock. A manufacturing method capable of ensuring the above is disclosed, for example, JP-A-62-150859.

[0005]

However, in the above manufacturing method, it is necessary to increase the number of photolithography and etching steps for forming the unevenness on the surface of the organic polymer protective film, which results in an increase in cost and yield. Decline,
There was a drawback that caused a drop in production efficiency.

An object of the present invention is to eliminate the above-mentioned drawbacks by forming irregularities on the surface of the organic polymer protective film in a smaller number of steps than in the manufacturing method.

[0007]

In order to eliminate the above-mentioned problems such as an increase in cost due to an increase in the number of steps, a decrease in yield, a decrease in production efficiency and the like, the present invention provides a method of patterning an organic polymer material protective film In addition, the number of manufacturing steps of the semiconductor device is reduced by forming a large number of concave portions utilizing the poor resolution together with the opening of the pad portion serving as the electrode lead portion on the surface of the protective film.

[0008]

According to the present invention, the uneven portion of the boundary surface between the mold resin body and the organic polymer protective film for improving the adhesion is improved when the pad portion serving as the electrode lead-out portion is opened. By utilizing a defect, the pad portion is formed and formed on the surface of the protective film. As a result, the number of manufacturing steps can be reduced.

The term "defective resolution" means that when a semiconductor substrate coated with a resist is exposed using a mask having a design pattern drawn, and the line width of the pattern is below the resolution limit, the exposure light is used as a resist. The phenomenon that the resist does not reach the bottom and, as a result, the resist cannot be completely removed and becomes a recess even if the phenomenon occurs.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor device manufacturing method of the present invention will be described in detail with reference to the drawings. 1A to 1D are process cross-sectional views of a method for manufacturing a semiconductor device according to the present invention. FIG. 2 is a diagram showing a mask pattern of the semiconductor device according to the present invention, and FIG. 3 is a diagram showing another mask pattern of the semiconductor device according to the present invention.

As shown in FIG. 1A, a semiconductor substrate 1 having a semiconductor element (not shown) and an aluminum electrode 2 formed thereon.
A passivation film made of an inorganic material, which is a PSG film 3 in this example, is formed on the entire surface. Next, as shown in FIG. 1B, the aluminum electrode 2 is exposed by photolithography and etching. Further, as shown in FIG. 1C, an organic polymer film, polyimide 4 in this example, is formed. Next in FIG.
A resist 5 is applied as shown in (d). After that, a mask having a 2 μm square pattern 22 in addition to the pattern 21 for exposing the aluminum electrode 2 as shown in FIG. 2 is used to expose and develop by a contact exposure method.

Here, in the contact exposure method, a pattern of 2 μm or less has a poor resolution, and the resist 5 in the portion corresponding to the pattern 25 is not completely exposed. As shown, the concave portion 6 is formed on the resist surface corresponding to the pattern 25. When the underlying polyimide 4 is etched using the resist 5 as a mask, the polyimide 4 in the portion corresponding to the recess 6 is slightly etched, and the recess 7 exposes the aluminum electrode 2 as shown in FIG. 1 (f). It is formed. After this, wire bonding and mold sealing are performed, as shown in FIG.
As shown in (4), the boundary surface between the polyimide 4 and the mold resin body 10 becomes an uneven surface, and the mechanical adhesion between them becomes large.
As a result, when a thermal shock is applied, no void is generated between the two, and the moisture resistance of the device can be secured.

Although the contact exposure method is used here, the same effect can be obtained by using a pattern having a resolution limit width or less if the exposure method has a resolution limit such as a reflection projection exposure method.

Although a 2 μm square pattern is formed on a mask as a pattern which causes poor resolution, it is possible to use a pattern such as (a) staircase shape or (b) cross shape as shown in FIG. Any shape may be used as long as it is a pattern drawn within the limit width.

Further, since the resolution limit width varies depending not only on the exposure apparatus but also on the sensitivity of the resist, it is necessary to consider the line width appropriately. Further, since the depth of the recess is related to the film thickness ratio between the resist and the protective film and the etching selection ratio, it is necessary to adjust the pattern width so as to have an appropriate depth. In this case, if a photosensitive organic polymer protective film is used instead of the organic polymer protective film, such adjustment becomes unnecessary.

Although the concave portion is provided on the organic polymer protective film here, it may be provided on any surface as long as it becomes a boundary surface with the mold resin body.

[0017]

As described above in detail, according to the present invention, the concave portion for improving the adhesion between the mold resin body and the protective film becomes the electrode lead portion by utilizing the poor resolution. Since the pad portion is formed at the same time when the pad portion is opened, moisture resistance after thermal shock can be obtained with a smaller number of steps than the manufacturing method disclosed in the above-mentioned JP-A-62-150859.
It is possible to reduce costs by reducing the number of steps, improve yield, and improve production efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor substrate in each step of a semiconductor device according to the present invention.

FIG. 2 is a diagram showing a mask pattern of a semiconductor device according to the present invention.

FIG. 3 is a view showing another mask pattern of the semiconductor device according to the present invention.

[Explanation of symbols]

 1 Silicon substrate 2 Aluminum electrode 3 PSG film 4 Polyimide film 5 Resist film 6 Recess on resist film 7 Recess on organic polymer film 8 Mold resin body 22 Electrode part exposure pattern 25 2 μm square pattern

Claims (1)

[Claims] 1. A step of preparing a semiconductor substrate in which a semiconductor element and a pad section to be an electrode lead section are formed on a main surface, a step of forming a protective film covering the main surface of the semiconductor substrate, and the pad section. A mask pattern having a first pattern for exposing the mask and a second pattern drawn with a line width that causes poor resolution, and the protective film is formed by photolithography and etching using the mask pattern. Thereby forming an opening at a position corresponding to the first pattern on the surface of the protective film, exposing the pad portion, and forming a recess at a position corresponding to the second pattern. Method.