JP5300120B2 - Thyristor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thyristor having a high gate-cathode breakdown voltage. <P>SOLUTION: On the first major surface of a first conductivity semiconductor substrate, a cathode region of a first conductivity impurity region, an anode region of a second conductivity impurity region surrounding the cathode region, and a mesa trench between the cathode region and the anode region are provided. On the second major surface of the semiconductor substrate, a gate region of a second conductivity impurity region, and a mesa trench having a depth reach the gate region from the first major surface are provided, a cathode metal electrode is provided in the cathode region on the first major surface, an anode metal electrode is provided in the anode region, and a gate metal electrode is provided on the gate region of the second major surface. Since a sufficient distance can be secured between the gate and the cathode in the thyristor, a high gate-cathode breakdown voltage can be ensured. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a switching element in the field of power electronics, and more particularly to a thyristor that requires a gate-cathode breakdown voltage as an application.

  Conventionally, this type of thyristor has a structure in which a cathode electrode and a gate electrode are formed on the same surface. (See Patent Document 1).

However, in the conventional thyristor formed in this way, in order to ensure a high gate-cathode breakdown voltage, the junction width between the gate region and the cathode region is small, so that a high breakdown voltage junction, that is, a low impurity concentration is achieved. It was difficult to ensure the junction and depletion layer width, and it was difficult to ensure the gate-cathode breakdown voltage.
JP-A-8-32049

  In the present invention, the gate-cathode breakdown voltage is increased by separating the gate-cathode breakdown structure into a first main surface and a second main surface, focusing on the problems of the prior art. An object of the present invention is to provide a thyristor structure that can be secured at a high level.

According to the thyristor of the present invention, the first main surface of the first conductivity type semiconductor substrate includes the cathode region which is the first conductivity type impurity region and the second conductivity type impurity region surrounding the cathode region. An anode region, and a mesa groove between the cathode region and the anode region, and a gate region that is a second conductivity type impurity region on all of the second main surface of the semiconductor substrate. And all the mesa grooves have a depth reaching from the first main surface to the gate region, the cathode region of the first main surface is a cathode metal electrode, and the anode region is an anode metal electrode And a thyristor having a gate metal electrode on the gate region of the second main surface.

  According to the thyristor of the present invention, an anode region and a cathode region are formed on the first main surface of the semiconductor substrate, and a gate region is formed on the second main surface, thereby ensuring a gate-cathode distance. High breakdown voltage can be secured.

  Hereinafter, description will be made based on examples of the present invention. 1, 2, and 3 are views showing a configuration of an embodiment of the present invention, in which FIG. 1 is a cross-sectional view of the thyristor taken along the line AA ′ in FIG. 3, and FIG. 3 is a bottom view. 4A to 4P are process diagrams showing manufacturing steps of the thyristor of the embodiment of FIGS.

  According to the thyristor of the embodiment of the present invention, as shown in FIG. 1 and FIG. 2, the semiconductor substrate is disposed at the center of the first main surface of the semiconductor substrate 2 of the first conductivity type (N−). A cathode region 4 of the first conductivity type (N +) having a concentration higher than 2 is formed, and is an impurity region of the second concentration type (P +) of high concentration so as to surround the cathode region 4 via the mesa groove 6. An anode region 3 is formed. Further, a gate region 5 of high concentration second conductivity type (P +) is provided on the opposite side of the semiconductor substrate 2 from the first main surface, and the mesa groove 6 reaches the gate region 5. Is formed.

  As shown in FIGS. 1 and 2, a cathode metal electrode 8 and an anode electrode 9 are formed on the surfaces of the cathode region 4 and the anode region 3 on the first main surface by a metal vapor deposition method or a plating method. A passivation film 7 such as a silicon oxide film or a glass protective film is formed on the surface including the mesa groove 6 other than the cathode metal electrode 8 and the anode metal electrode 9 on the main surface.

  As shown in FIGS. 1 and 3, the gate metal electrode 10 is formed on the second main surface by a metal vapor deposition method or a plating method.

A manufacturing process of the thyristor of the embodiment shown in FIGS. 1, 2, and 3 of the present invention will be described with reference to FIGS. 4A to 4P.
A semiconductor substrate 2 of the first conductivity type (N−) is prepared (FIG. 4A), and an oxide film 11 is formed on the first main surface and the second main surface by a thermal oxidation method or the like (FIG. 4B). Next, resist application, exposure, development, and oxide film etching are performed in the photographic process, and the oxide film 11 in the anode region portion of the first main surface of the semiconductor substrate 2 is removed (FIG. 4C). Here, boron or the like of the second conductivity type impurity is deposited to form the anode region 3 as the second conductivity type impurity region (FIG. 4D). Next, an oxide film 11 is formed again (FIG. 4E), and the oxide film 11 in the cathode region is removed by a photographic process (FIG. 4F), where a first conductive type (N +) impurity such as phosphorus is removed. Positioning is performed to form the cathode region 4 (FIG. 4G).

  Next, the oxide film 11 is also formed by the thermal diffusion process in conjunction with the thermal diffusion processing of the anode part and the cathode part (FIG. 4H). In the photographic process, the oxide film 11 is removed from the anode portion on the first main surface and the gate portion on the second main surface (FIG. 4I). Here, deposition of boron or the like of the second conductivity type impurity is performed, and thermal diffusion treatment is performed to form the high-concentration ohmic portion 12 and the gate region portion 5 in the anode region portion (FIG. 4J).

  Next, the oxide film 11 in the mesa groove forming portion on the first main surface is removed by a photographic process (FIG. 4K), and a mesa groove portion 6 is formed by a silicon etching process (FIG. 4L). Next, a passivation film 7 such as glass is formed on the first main surface (FIG. 4M), and the passivation film 7 and the oxide film 11 in the electrode contact window are removed by a photographic process (FIG. 4N). A metal film is formed on the first main surface by a metal vapor deposition method or the like, an anode metal electrode portion 9 and a cathode metal electrode portion 8 are formed by a photographic process (FIG. 4O), and a metal vapor deposition method or the like is also formed on the second main surface. Then, the gate metal electrode portion 10 is formed (FIG. 4P).

  According to the embodiment of the thyristor of FIGS. 1, 2 and 3 formed in the steps of FIGS. 5A-5P, the cathode is arranged on the first main surface and the gate is arranged on the second main surface as compared with the conventional structure example. As a result, the gate-cathode distance can be dramatically increased and the gate-cathode breakdown voltage can be increased.

FIG. 4 is a cross-sectional view taken along line A-A ′ of FIG. The top view of FIG. The bottom view of FIG. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention. The manufacturing process figure of the thyristor of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Semiconductor substrate of 1st conductivity type 3 Anode area 4 Cathode area 5 Gate area 6 Mesa groove part 7 Passivation film 8 Cathode metal electrode 9 Anode metal electrode 10 Gate metal electrode 11 Oxide film 12 High concentration ohmic of anode area Part

Claims (1)

The first main surface of the first conductivity type semiconductor substrate has a cathode region that is an impurity region of the first conductivity type, an anode region that is an impurity region of the second conductivity type surrounding the cathode region, and the cathode There is a mesa groove between the region and the anode region, and all of the second main surface of the semiconductor substrate has a gate region which is a second conductivity type impurity region, and the mesa groove is , All having a depth reaching from the first main surface to the gate region, the cathode region of the first main surface having a cathode metal electrode, the anode region having an anode metal electrode, and the second main surface A thyristor comprising a gate metal electrode on the gate region of a surface.