JPH0684886A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve reliability of an element and to improve humidity resistance life thereof by improving adhesion of a protection polyimide resin film. CONSTITUTION:A collector region 2, a base region 3 and an emitter region 4 are formed inside a semiconductor substrate 2. An insulation film 5 consisting of a thermal oxide SiO2 film, a base electrode 3a and an emitter electrode 4a are formed on a surface of the semiconductor substrate 1. V-shaped grooves 7 are formed on a surface of the semiconductor substrate 1 to enclose the base region 3 and the emitter region 4. A polyimide region film 6 is laminated on the insulation film 5, the base electrode 3a and the emitter electrode 4a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device.

[0002]

2. Description of the Related Art Recently, a semiconductor device in which a semiconductor substrate surface on which a semiconductor element is formed is covered with a protective polyimide resin film has been widely used. The polyimide-based resin film has advantages such as fewer defects, a thick film can be formed, and a flat film can be easily formed on an uneven substrate as compared with an inorganic insulating film such as SiO ₂ or SiN.

FIG. 3 shows a semiconductor device in which the surface of a semiconductor substrate on which a PNP transistor is formed is covered with a protective polyimide resin. In this element, a collector region 22, a base region 23 and an emitter region 24 are formed in a semiconductor substrate 21, and an insulating film 25 made of a thermally oxidized SiO ₂ film, a base electrode 23a, an emitter are formed on the surface of the semiconductor substrate 21. An electrode 24a is formed (the collector electrode is formed on the front surface or the back surface of the semiconductor substrate 21 not shown). Then, the insulating film 25 and each electrode 2
A polyimide resin film 26 is formed so as to cover 3a and 24a. The polyimide resin film 26 is provided to protect the semiconductor element from mechanical stress and improve moisture resistance.

When the PNP transistor is sealed with a resin, the semiconductor substrate 21 is fixed to the lead frame 27 for extracting external electrodes, the lead frame 27 and each electrode are connected with a wire 28 of gold or aluminum, and finally the sealing resin is used. Two
Seal with 9.

[0005]

However, in the above semiconductor device, when the semiconductor device is exposed to a temperature change and a high humidity atmosphere, the difference in coefficient of thermal expansion between the sealing resin 29 and the semiconductor substrate 21 or moisture absorption. Due to the swelling of the resin due to, a gap is generated at the interface between the sealing resin 29 and the semiconductor substrate 21. Moisture contained in the outside air enters through the gap and reaches the surface layer of the semiconductor substrate 21.

In general, the adhesion between non-metal materials such as silicon and silicon dioxide and the resin is remarkably lowered by the intervention of water. Therefore, the water reaching the surface of the semiconductor substrate 21 through this gap reduces the adhesion between the semiconductor substrate 21 and the insulating film 25 and the polyimide resin film 26,
It reaches the base electrode 23a. As a result, the reverse breakdown voltage between the base and collector occurs due to the presence of water, and the semiconductor device does not function as a semiconductor device.

The present invention has been made in view of the above problems, and an object thereof is to provide a highly reliable semiconductor device in which the adhesion of the protective polyimide resin film does not deteriorate. .

[0008]

In order to solve the above problems, the present invention forms a groove surrounding the semiconductor element on the surface of the semiconductor substrate on which the semiconductor element is formed, and the groove and the semiconductor element are made of a polyimide-based material. It is characterized by being covered with a resin film.

Examples of the semiconductor element include a transistor (for example, a bipolar transistor, a MOS transistor, etc.) and a thyristor (for example, an electrostatic induction thyristor), but the semiconductor element is not limited to these. Further, an integrated circuit in which a plurality of semiconductor elements are formed on one semiconductor substrate may be used.

The shape of the groove is V-shaped or U-shaped, and the depth of the groove is about 10 to 20 μm. The groove is formed by the well-known photolithographic technique and selective etching technique.

As the polyimide resin, for example, a polyimide resin film having a thickness of about 5 to 7 μm is used. A modified polyimide resin may be used. The polyimide resin film is formed by, for example, applying a photosensitive liquid polyimide resin composition to a semiconductor substrate, performing pre-baking, then performing exposure / development / rinsing processing for pattern formation of bonding pads, and post-baking. It

[0012]

In the semiconductor device according to the present invention, since the groove surrounding the semiconductor element is formed on the surface of the semiconductor substrate, the area of the contact portion between the polyimide resin and the semiconductor substrate increases. That is, the total adhesion between the polyimide resin and the semiconductor substrate is increased.

Further, as a water infiltration route, a route from the chip edge portion to the chip central portion mainly at the interface between the polyimide resin and the semiconductor substrate can be considered. However, since the groove is formed, the chip edge portion leads to the element. As the distance to the formation part becomes longer, as described above, it takes time for the water to reach the part that affects the device characteristics, even if it is exposed to the high temperature and high humidity atmosphere and the water infiltrates. The moisture-proof life is improved.

[0014]

1 shows a semiconductor device having a planar type PNP transistor element according to an embodiment of the present invention.

In this semiconductor device, a collector region (P region) 2, a base region (N region) 3 and an emitter region (P region) 4 are formed in a semiconductor substrate 1, and the surface of the semiconductor substrate 1 is An insulating film 5 made of a thermally oxidized SiO ₂ film, a base electrode 3a, and an emitter electrode 4a are formed (the collector electrode is formed on the front surface or the back surface of the semiconductor substrate 1 not shown).

The base region 3 is formed on the surface of the semiconductor substrate 1.
Further, a V-shaped groove 7 is formed so as to surround the emitter region 4, and a polyimide resin film 6 is laminated on the insulating film 5, the base electrode 3a and the emitter electrode 4a. This groove 7
Is 70 to 80 ° C. for a (100) silicon substrate.
With a mixed solution of potassium hydroxide / water / ethyl alcohol / isopropyl alcohol as an etching solution,
It is formed using the silicon oxide film as a mask. In this example, etching was performed for 45 minutes to form a V groove having a depth of about 20 μm.

Next, FIG. 2 shows a different embodiment of the present invention, showing a semiconductor device having a surface gate type electrostatic induction thyristor element.

This semiconductor device has an anode region (P region) 12 and an anode electrode 12 on the back surface side of the semiconductor substrate 11.
a, the cathode region (N
Region 13), a gate region (P region) 14, a cathode electrode 13a and a gate electrode 14a, and a high specific resistance region (N
Region 18) and has a surface gate type thyristor structure. An insulating film 15 made of a thermally oxidized SiO ₂ film is formed on the surface of the semiconductor substrate 11.

Then, the gate region 14 and the cathode region 1
3, a V groove 17 is formed so as to surround the insulating film 15,
A polyimide resin film 16 is laminated on the cathode electrode 13a and the gate electrode 14a.

Of course, the present invention is not limited to the above-described embodiment, and the grooves 7 and 17 may be U-shaped or trench-shaped, for example. Also, a plurality of grooves 7 and 17 may be provided.

[0021]

As described above, the present invention provides a highly reliable semiconductor device in which the adhesion between the polyimide resin film and the semiconductor substrate is improved by forming the groove surrounding the semiconductor element on the surface of the semiconductor substrate. can do. Further, when exposed to a high humidity atmosphere, the path of moisture penetration into the element portion becomes long, and the moisture resistance life can be greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a different embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a conventional example.

[Explanation of symbols]

 1,11 Semiconductor substrate 6,16 Polyimide resin film 7,17 Groove

Claims (1)

[Claims] 1. A semiconductor device, comprising: forming a groove surrounding the semiconductor element on the surface of a semiconductor substrate having the semiconductor element formed thereon; and coating the groove and the semiconductor element with a polyimide resin film.