JPH06151824A - Manufacture of inverse continuity gto thyristor - Google Patents

Abstract

PURPOSE:To solve a problem where n<+> region is generated at the layer of a diode part and the amount of inverse recovery resistance is reduced due to the process failure when forming an emitter layer of the GTO part of an inverse continuity GTO thyristor by diffusion. CONSTITUTION:By forming a P<+> layer 12 by diffusion an impurity from the surface of the p layer of a diode part 20 after the diffusion process for forming an n emitter layer 4 of a GTO part 10, n<+> region generated at that part can be collapsed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse conducting G in which an antiparallel diode is built in the same semiconductor substrate as a GTO thyristor.
The present invention relates to a method of manufacturing a TO thyristor.

[0002]

2. Description of the Related Art A reverse conducting GTO thyristor is a GTO thyristor and a freewheel diode formed on the same semiconductor substrate, and is used in power converters such as high withstand voltage, large current inverters, converters, and chippers. Figure 2
The cross-sectional structure of a conventional reverse conducting GTO thyristor is shown in FIG. As shown in the figure, the GTO section 10 and the p-layer having a four-layer structure of pnpn and p
A diode portion 20 having a two-layer structure of n is integrated on the same silicon substrate. The GTO section 10 includes a p-emitter layer 1,
It is composed of the n base layer 2, the p base layer 3, and the n emitter layer 4, and a current flows in the direction from the anode electrode 5 to the cathode electrode 6, and the current can draw the gate current from the gate electrode 7 on the p base layer 3. Cut off by. On the other hand, the diode part 20 comprises an extension part of the n-layer 2 and an extension part of the p-layer 3, and the n-layer 2 contacts the extension part of the anode electrode 5 through the n ⁺ contact layer 8 and is formed on the p-layer 3. The provided diode anode electrode 9 is brought into contact with the cathode electrode 6 of the GTO unit 10 integrally by a metal contact plate (not shown). In this way, the diode 20 is connected in antiparallel to the GTO 10. The n ⁺ layer 8 of the diode section 20
At the time of formation, the p-type emitter layer 1 is selectively formed on the entire surface of the GTO portion to form an anode short-circuit structure in which the n layer 2 is connected to the anode electrode 5 to accelerate the switching speed. .

[0003]

Such a reverse conduction GT
When operating an O thyristor at high frequency, the current rise rate di /
By increasing dt and reducing the capacity of the GTO snubber capacitor
The responsibility on the diode also increases. As shown in Figure 2
In this structure, diffusion of the n-emitter layer 4 is performed in the manufacturing process.
Sometimes the oxide film peels off⁺The diffusion area is p of the diode section 20.
It may be formed on the surface of the extension of the base layer 3. This
Sea urchin⁺When the region remains on the surface of the p base layer 3, it becomes conductive.
When the reverse recovery from the
Degree n⁺Holes are injected into the region,
It operates as a diode and there is no delay in reverse recovery as a diode.
It Therefore, the p layer 3 surface slightly generated in the manufacturing process
Face n ⁺The current concentrates on the region, which leads to device destruction.

An object of the present invention is to prevent the formation of another conductivity type region on the surface of the base layer in contact with the gate electrode of the GTO portion and prevent the reverse recovery withstand capability of the diode portion from being lowered. It is to provide a method of manufacturing a reverse conducting GTO thyristor capable of performing.

[0005]

In order to achieve the above-mentioned object, the present invention is to remove impurities from the surface of the first conductivity type base layer adjacent to the second conductivity type base layer on the other side in the GTO thyristor portion. A method of manufacturing a reverse conducting GTO thyristor, which comprises diffusing to form a second conductivity type emitter layer, comprising:
After forming the second conductivity type emitter layer of the thyristor part, impurities are diffused from the surface layer of the first conductivity type base layer extension, which is one layer of the pn junction of the diode part, to form a first conductivity type high impurity concentration layer. Shall be formed. And forming a high impurity concentration layer of the first conductivity type by impurity diffusion by covering the GTO thyristor portion with a mask made of an oxide film,
Impurities are introduced from the entire surface of the second-conductivity-type base layer to form a second-conductivity-type high-impurity-concentration layer, and then impurities are diffused from the surfaces of a plurality of GTO thyristor portions to form the first-conductivity-type emitter layer. Is effective.

[0006]

By forming a high impurity concentration layer of the first conductivity type on the surface layer of the extension of the first conductivity type base layer, the second surface layer of the first conductivity type layer of the diode portion caused by the manufacturing process failure The conductivity type region is eliminated to prevent current concentration during reverse recovery.

[0007]

1 (a) to 1 (d) show a part of the manufacturing process of an embodiment of the present invention, and the same parts as those in FIG. 2 are designated by the same reference numerals. First, impurities are diffused from one surface of the n-type silicon substrate 2 to be the n-base layer to diffuse the p-base layer 3.
Next, the n emitter layer 4 is formed by selectively diffusing the impurities from a plurality of portions of the surface of the region of the p base layer 3 which will be the GTO portion using a SiO ₂ film mask. At this time, it is assumed that the n ⁺ region 41 is generated in the p layer 3 of the diode portion due to the defect of the mask. Further, different impurities are diffused from the other surface to form an n ⁺ layer 8 serving as a diode contact layer [(a) in the same figure].
Then, both surfaces are covered with the SiO ₂ film 11 [FIG. After that, the SiO ₂ film 11 is masked and impurities are introduced from the surface to form a p ⁺ layer 12 having a surface impurity concentration of 1 × 10 ¹⁹ atoms / cm ^{3 on} the surface layer of the p base layer 3 of the diode portion 20, GT
A p-emitter layer 1 is formed so as to penetrate the n ⁺ layer 8 on the back surface of the O portion 10 [FIG. As a result, the diode section
P ⁺ layer that crushes n ⁺ region 41 caused by defective manufacturing process
12 is formed, and an anode short circuit structure is completed in the GTO part. The p ⁺ layer 12 also helps ensure the ohmic contact of the diode anode electrode 9.

Although FIG. 3 was manufactured in the same process as FIG. 1,
It is a reverse conducting GTO thyristor according to an embodiment of the present invention in which an n emitter layer 4 is formed in a segment.

[0009]

According to the present invention, a contact layer having a high impurity concentration is formed in the diode portion of the reverse conducting GTO thyristor and the electrodes are brought into contact with each other. It was possible to eliminate the conductivity type region and prevent the reverse recovery withstand capability from decreasing due to current concentration in that region.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of a manufacturing process of a reverse conducting GTO thyristor according to an embodiment of the present invention in the order of (a) to (d).

FIG. 2 is a cross-sectional view of a conventional reverse conducting GTO thyristor.

FIG. 3 is a sectional view of a reverse conducting GTO thyristor according to another embodiment of the present invention.

[Explanation of symbols]

1 p emitter layer 2 n base layer 3 p base layer 4 n emitter layer 5 GTO anode electrode 6 GTO cathode electrode 7 GTO gate electrode 8 n ⁺ layer 9 diode anode electrode 10 GTO part 11 SiO ₂ film 12 p ⁺ layer 20 diode part

Claims (3)

[Claims] 1. A reverse conducting GTO thyristor for forming an emitter layer of a second conductivity type by diffusing impurities from the surface of a first conductivity type base layer adjacent to the second conductivity type base layer on the other side in the GTO thyristor portion. In the manufacturing method, after the second conductivity type emitter layer of the GTO thyristor part is formed, impurities are diffused from the surface layer of the first conductivity type base layer extension part which is one layer of the pn junction of the diode part to diffuse the impurities of the first conductivity type. A method of manufacturing a reverse conducting GTO thyristor, which comprises forming a high impurity concentration layer. 2. The method for manufacturing a reverse conducting GTO thyristor according to claim 1, wherein the high-concentration impurity layer of the first conductivity type is formed by impurity diffusion by covering the GTO thyristor portion with a mask made of an oxide film. 3. An impurity is introduced from the entire surface of the second-conductivity-type base layer to form a second-conductivity-type high-impurity-concentration layer, and then surfaces of a plurality of the second-conductivity-type layers of the GTO thyristor portion. 3. The method for manufacturing a reverse conducting GTO thyristor according to claim 1, wherein impurities are diffused from the first conductive type emitter layer to form a first conductive type emitter layer.