JP3196567B2 - Pressure contact type semiconductor device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure contact type flat semiconductor device such as an amplification gate type thyristor having a gate electrode structure of a complicated shape such as a high speed thyristor or a large diameter thyristor.

[0002]

2. Description of the Related Art In a high-speed thyristor or a large-diameter thyristor, a cathode electrode disposed on a main surface of a semiconductor substrate (a diffusion bonded body in which a pnpn layer is formed on a silicon wafer) is used most effectively. It is common design practice to have an intricate and complex shaped amplification gate electrode.

FIG. 5 is a structural view of an amplifying gate thyristor having a gate electrode structure of a complicated shape. FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along line AA in FIG. The figure is shown. On the main surface of the semiconductor substrate 1, a cathode electrode 103, a gate electrode 101 and an amplification gate electrode 102 are arranged. The operation of the thyristor is as follows. When a gate current is supplied as a + power supply to the gate electrode 101 and a − power supply is supplied to the cathode electrode 103, the gate current and the current amplified by the amplification gate electrode 102 (the pnpn thyristor at this point is turned on) Thyristor is turned on. In order for the thyristor having such a structure to always maintain normal operation, it is necessary to completely separate the cathode electrode 103, through which the main current flows, from the other electrodes including the gate electrode 101 and the amplification gate electrode 102. is there. The semiconductor substrate 1 is fixed to the support plate 10 with an alloy or the like. Next, a conventional example of a completely separated structure is shown in FIGS.

FIG. 6 is a cross-sectional view when the semiconductor substrate 1 and the cathode contact plate 3 are fixed with an adhesive 4 such as silicone rubber. FIG. 7 shows that the gate electrode 101 and the amplification gate electrode 102 of the semiconductor substrate 1 are provided with a step 1a by an etching technique, and the cathode contact plate 3 having a simple circular opening in the portion corresponding to the gate electrode 101 is connected to the semiconductor substrate. 1 is a cross-sectional view in the case of contacting with a reference numeral 1 and being fixed by a positioning ring 5 on the outer periphery.

[0005] FIG. 8 shows a high-concentration diffusion layer 6 formed by diffusing a high-concentration impurity immediately below the step 1a in order to solve the problem of FIG.
FIG. 4 is a cross-sectional view of a structure in which the ON operation can be easily performed without lowering the resistance of this portion and generating an excessive voltage. FIG. 9 shows a method of drastically solving the problem of FIG. 7 by covering the amplifying gate electrode 102 with an insulating film 7 (for example, polyimide resin, silicone resin, etc.), and amplifying the gate electrode 102 and the cathode contact plate 3. FIG. 4 is a cross-sectional view of a structure excluding the danger of discharge.

[0006]

In the structure shown in FIG. 6, the adhesive 4 such as silicone rubber penetrates into the gap between the cathode contact plate 3 and the cathode electrode 103 on the semiconductor substrate 1 by capillary action, and the electrical contact failure is reduced. There is a high risk of starting. In the structure of FIG. 7, the electric resistance increases due to the provision of the step 1a.
An excessive voltage is generated at the amplification gate electrode by the above-described amplified current flowing through the gate electrode 03, and there is a high risk of causing a discharge between the amplification gate electrode 102 and the cathode contact plate 3.

In the structures shown in FIGS. 6 to 9, the number of working steps such as step formation, high-concentration impurity diffusion, insulating film deposition, etc. is greatly increased. There are many problems, such as variations in resistance (gate impedance) values, making it difficult to ensure stable ignition characteristics and turn-on characteristics. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a press-contact flat type semiconductor device in which a cathode contact plate is reliably separated from a gate electrode and an amplification gate electrode, and has high reliability in element characteristics and good assemblability. And

[0008]

In order to achieve the above object, an amplification gate electrode having radial irregularities and a cathode electrode surrounding the amplification gate electrode are formed on a main surface of a semiconductor substrate. In the case where the outer peripheral portion is covered with a passivation film, a part of the cathode contact plate that is in contact with the cathode electrode is fixed to the passivation film.

An opening having a contour larger than that of the amplification gate electrode is provided at the center of the cathode contact plate, and a projection is provided at the outer periphery of the cathode contact plate. The projection may be fixed by a passivation film. In addition, the projection of the cathode contact plate is bent substantially at a right angle, further bent substantially perpendicularly in the outer peripheral direction at the same height as the thickness of the passivation film, and the bent portion is brought into contact with the surface of the passivation film, This refolded portion may be fixed to the surface of the passivation film with an adhesive.

[0010] Further, a projection formed on the same plane as the cathode contact plate may be brought into contact with the semiconductor substrate, and the projection may be fixed by a passivation film. The cathode contact plate is made of a material such as molybdenum manufactured by a rolling method. The thickness of the cathode contact plate is 0.1 to 0.3 mm. The processing is preferably performed by punching, and the bending of the protrusion is preferably performed by drawing.

[0011]

The cathode contact plate is formed on the cathode electrode by providing an opening having a profile slightly larger than the amplification gate electrode on the cathode contact plate and fixing the projection provided on the outer peripheral end of the cathode contact plate to the passivation film. It is positioned and fixed, and the distance between the amplification gate electrode and the cathode contact plate is reliably ensured.

[0012]

FIG. 1 is a schematic diagram showing a main part of a first embodiment of the present invention. FIG. 1A is a plan view, and FIG.
FIG. The cathode electrode 103, the gate electrode 101, and the amplification gate electrode 10
2 are formed. The planar shape of the amplification gate electrode 102 is not circular, but is, for example, a shape in which four arms are extended.
The inner end of the cathode electrode 103 faces the outer end of the amplification gate electrode 102 in parallel. The outer peripheral portion of the semiconductor substrate 1 is covered with a passivation film 2. The shape of the outer peripheral portion has a special shape such as a positive bevel in order to secure a withstand voltage, but is simplified here. The support plate is not fixed to the other surface of the semiconductor substrate 1. The central portion of the cathode contact plate 3 is opened slightly larger than the inner end of the cathode electrode 103, and has a structure that does not contact the amplification gate electrode 102 or the gate electrode 101. Further, the outer peripheral end of the cathode contact plate 3 is slightly smaller than the inner end of the passivation film 2 and reliably contacts the cathode electrode 103 by the applied pressure. A projection 31 is formed on a part of the outer peripheral end of the cathode contact plate 3.
The projection 31 is bent substantially at a right angle, and further bent substantially at right angles in the outer peripheral direction by the thickness of the passivation film 2.
2 is fixed to the surface of the passivation film 2 with an adhesive 4. FIG. 7A shows the projection 32 bent again, and a cross-sectional view of the entire projection 31 is shown in FIG. The passivation film 2 is formed of a silicone resin, a polyimide resin, or the like, and has a thickness of several mm.
The material of the cathode contact plate 3 is molybdenum, tungsten, or the like. The central opening and the projection are formed by punching, and the projection is bent by drawing. In order to facilitate this processing, the thickness of the molybdenum plate or the tungsten plate is 0.1 to 0.3 mm. After the processing, a heat treatment for removing the processing distortion in a hydrogen reducing atmosphere may be performed. The material of the adhesive 4 used for fixing the projection is silicone rubber or the like. FIG. 2 is a sectional view showing a main part of a second embodiment of the present invention. FIG. 3 is a cross-sectional view corresponding to a section taken along line AA of FIG. 1B is different from FIG. 1B in that a part of the surface of the passivation film 2 is shaved off and the bent protruding portion 32 is fixed with an adhesive 4. This is effective when the height of the bent portion of the projection 31 cannot be increased, that is, when a material that is difficult to perform a large drawing process is used.

FIG. 3 is a sectional view showing a main part of a third embodiment of the present invention. This figure is also a cross-sectional view corresponding to a section taken along the line AA in FIG. The projection 31 is not bent and is brought into contact with the surface of the semiconductor substrate, and is fixed by the passivation film 2.
This is effective when a material that cannot be drawn at all is used. In this case, a ring-shaped groove is provided on the outer peripheral portion of the cathode contact plate 3 so that the silicone rubber forming the passivation film does not penetrate between the cathode electrode 103 and the cathode contact plate 3 due to a capillary phenomenon. It is necessary to store the rubber in the groove and take measures to prevent the rubber from penetrating therethrough.

FIG. 4 is a view showing the shape of the projection 32 bent again. FIG. 4A is a diagram showing the first shape, and FIG.
Shows a second shape diagram, and FIG. 3C shows a third shape diagram. These shapes show the shape of the tip of the bonding portion of the projection 32 that is bent again, and the bonding portion is more firmly fixed by adopting such a notch.

[0015]

According to the present invention, the gate electrode and the amplifying gate electrode are reliably separated from the cathode contact plate, and a short circuit and discharge between the gate electrode and the amplifying gate electrode and the cathode contact plate can be prevented. A flat-contact type semiconductor device having high reliability in characteristics and good assemblability was obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of a first embodiment of the present invention, and FIG.
Is a plan view, and (b) is a cross-sectional view of an AA cut portion of (a).

FIG. 2 is a sectional view of a main part of a second embodiment of the present invention.

FIG. 3 is a sectional view of a main part of a third embodiment of the present invention.

FIG. 4 is a diagram showing a shape of a bonding portion of a protrusion.

5A and 5B are structural views of an amplification gate type thyristor, wherein FIG. 5A is a plan view and FIG. 5B is a cross-sectional view taken along line AA of FIG.

FIG. 6 is a sectional view of a conventional example in which a semiconductor substrate 1 and a cathode contact plate 3 are fixed with an adhesive 4 such as silicone rubber.

FIG. 7 is a cross-sectional view of a conventional example in which a step is formed in a portion of a gate electrode and an amplification gate electrode of a semiconductor substrate.

FIG. 8 is a sectional view of a conventional example in which a high-concentration impurity is diffused immediately below a step;

FIG. 9 is a cross-sectional view of a conventional example in which an insulating film is deposited on an amplification gate electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 1a Step 2 Passivation film 3 Cathode contact plate 4 Adhesive 5 Alignment ring 6 High concentration diffusion layer 7 Insulating film 10 Support plate 101 Gate electrode 102 Amplification gate electrode 103 Cathode electrode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/52 H01L 29/74

Claims (6)

(57) [Claims] 1. A semiconductor substrate in which an amplification gate electrode having irregularities in a radial direction and a cathode electrode surrounding the amplification gate electrode are formed on a main surface of a semiconductor substrate, and the outer periphery of the semiconductor substrate is covered with a passivation film. A flattened contact type semiconductor device, wherein a part of a cathode contact plate which is in contact with the semiconductor device is fixed to a passivation film. 2. An opening having a contour larger than the amplification gate electrode is provided at the center of the cathode contact plate, and a projection is provided on the outer periphery of the cathode contact plate, and the projection is fixed by a passivation film. The flattened semiconductor device according to claim 1, wherein: 3. The projection of the cathode contact plate is bent substantially at a right angle, further bent substantially at right angles in the outer peripheral direction at the same height as the thickness of the passivation film, and the portion bent again is formed on the surface of the passivation film. 3. The flattened semiconductor device according to claim 2, wherein said bent portion is fixed to the surface of the passivation film with an adhesive. 4. The projection of the cathode contact plate is bent substantially at a right angle, and further bent substantially perpendicularly to the outer periphery at a height smaller than the thickness of the passivation film, and the projection bent again is formed of the projection of the passivation film. 3. The flattened semiconductor device according to claim 2, wherein the semiconductor device is fixed to a part of the surface with a part removed by an adhesive. 5. The flattened semiconductor according to claim 2, wherein a projection formed on the same plane as the cathode contact plate is brought into contact with the semiconductor substrate, and the projection is fixed with a passivation film. Device manufacturing method. 6. The cathode contact plate is a metal material manufactured by a rolling method, and has a thickness of 0.1 to 0.3.
3. The pressure contact according to claim 2, wherein the outer peripheral edge including the opening and the projection of the cathode contact plate is worked by punching, and the projection is bent by drawing. A method for manufacturing a flat semiconductor device.