JPS63141370A - Manufacture of thyristor - Google Patents

Abstract

PURPOSE:To remove a thin section and the formation of air bubbles in the case of a JCR and thoroughly protect its surface by causing a thyristor element to rotate under a state in which its element is held almost in the vertical direction on the occasion of applying the JCR to a bevel part of the thyristor element having a SIGMA bevel. CONSTITUTION:A thyristor element 10 where a silicon substrate 1 is glued to its Mo support plate 2 is fit in a chuck jig 7 and a central axis 71 of its jig 7 is held by obtaining an inclination of 20 deg. to a level surface. Its rotation axis 71 of the chuck jig is connected to a motor 8 and its motor 8 is supported by a prop 82 that is vertically erected on a stand 81. The motor 8 rotates at a low speed in this state and allow a dispenser 9 to drip a JCR 5 to a bevel part of the substrate 1 so as to apply it. After applying it, a primary drying of the JCR 5 is performed while the element 10 rotates. In the case of applying it, as the rotation axis is so inclined to a horizontal plane that a lower part of JCR 5 becomes slightly thick. However, it is also true that since its element 10 is held almost vertically, no adhesion of JCR 5 to the sides of the Mo plate 2 and no development of thin parts of the JCR on an upper part of a SIGMA bevel or of the remainder of air bubbles in the JCR are caused when the JCR is applied.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is characterized in that three layers of alternately different conductivity types are adjacent to each other via bonds parallel to the substrate surface, and the cross-section of the substrate parallel to the substrate surface is sigma whose area is smallest at the center of the plate thickness
(Σ) A method of manufacturing a thyristor having a bevel structure.

[Problem that the invention seeks to solve]

In order to reduce the surface electric field strength when a reverse bias is applied to the PN junction sandwiching the high-resistance base layer of a high-voltage thyristor, the exposed portions of both PN junctions to the side surfaces of the substrate are made to have positive bevels. pNpN4 as shown in Figure 2
F! A Σ bevel structure is known in which the side surface of the silicon substrate l having the t is formed so as to have a V-shaped cross-sectional shape.

Such a thyristor consists of a silicon substrate 1 and a Mo plate 2 serving as a support plate bonded with an alloy, and a gate electrode 3. After the cathode electrode 4 has been deposited, the side surface of the substrate 1 is processed into a Σ bevel using a sand blasting method or a diamond cutter, and the thyristor element lO with the beveled part etched is placed on a flat surface and rotated about the central axis 11. Then, a bonding coating resin (hereinafter referred to as JCR) 5 was applied. However, with this method, JCR5 flows out to the side of the Mo plate 2 as shown in the figure, which obstructs highly accurate assembly.
JCR5 on the side of plate 2 had to be completely removed.

In addition, as shown in Fig. 3, J C
There is also a method of applying JCR5 by providing an R flow stopper 21, but this method is also similar to the method described above, since the JCR5 is applied at the top of the Σ bevel.
The thickness of CR5 becomes thinner. Therefore, in order to ensure a sufficient thickness of the JCR 5, a ring 22 having the same inner diameter as the diameter of the Mo plate 2 is placed around the element 10, as shown in FIG. A stop is provided to connect the JC between the ring 22 and the thyristor board 1.
There is a method of filling R5.

[Problem that the invention seeks to solve]

As mentioned above, when trying to apply JCR to a thyristor element with a Σ bevel structure, the method shown in FIGS. 2 and 3 produces a thin part of JCR5.
A high breakdown voltage thyristor exceeding 0 V has the disadvantage that discharge occurs at a thin JCR. Furthermore, the method shown in FIG. 4 also has the disadvantage that gas escape is obstructed by the protruding portion of the bevel and bubbles 24 are likely to form at the top of the Σ bevel, causing discharge at the bubble portion.

The object of the present invention is to reduce the thickness of JCR, which causes discharge, when applying JCR to the side surface of a thyristor substrate having a Σ bevel structure where the cross-sectional area of the substrate parallel to the substrate surface is the smallest at the center of the thickness. There are no thin areas or bubbles,
An object of the present invention is to provide a method for manufacturing a thyristor with sufficient surface protection and high reliability.

[Means for solving problems]

In order to achieve the above object, the method of the present invention is to apply JCR by dropping JCR from above the side surface of the thyristor substrate while rotating the thyristor substrate with the surface substantially vertical, and then drying the thyristor substrate.

[Effect]

By applying JCR to the side of the board that rotates in a vertical state, the JCR will not stick to the bottom of the Σ bevel due to gravity or run down to the side of the support plate, and the opening of the Σ bevel will be directed upward. The exposed portion of the PN junction can be protected by the JCR, which has a nearly uniform thickness, so that gas can easily escape, leaving no bubbles.

〔Example〕

FIG. 1 shows a JCR coating device according to an embodiment of the present invention,
Parts common to those in FIGS. 2 to 4 are given the same reference numerals.0 For example, a thyristor element 10 in which a silicon substrate 1 with a diameter of 82 mm is bonded to a support plate 2 with a diameter of 85 mm is attached to a chuck jig 7. Fit and hold the central axis 71 of the chuck jig 7 at an angle of 20'' with respect to the horizontal. This prevents the element 10 from falling off the jig 7, and the chuck jig rotating shaft 71 is connected to the motor 8. The motor 8 is supported by a support 82 placed on a stand 81. In this state, the motor 8 is rotated at low speed, and JCR5 is applied by dropping it onto the bevel portion of the substrate 1 from the dispenser 9. .After coating, do not rotate the element 10.
By performing primary drying of R, it is possible to obtain a thyristor element 10 whose Σ bevel surface is protected by JCR5 as shown in FIG.

Since the rotation axis during application is tilted with respect to the horizontal, JCR
5 is slightly thicker at the bottom, but because the element 10 is held in a nearly vertical state, JCR5 is similar to Mo board 2.
This eliminates adhesion to the sides of the Σ bevel, as well as the formation of air bubbles in the thin part of JCR5 on the top of the Σ bevel or in the JCR.

In this embodiment, the element IO whose Σ bevel portion has been etched is attached to the chuck jig 7, but this coating device can also be used to perform the steps from etching to JCR coating.

(Effects of the Invention) According to the present invention, when applying JCR to the worn bevel portion of a thyristor element having a Σ bevel, the thyristor element is rotated while being held in an almost vertical direction, so that the JCR remains on the bevel surface. It does not leak to unnecessary areas, and there is no thin part of the JCR at the top of the bevel.Also, since the Σ bevel opens upwards during application, it is easy for gas to escape from the JCR, making the JCR thicker. As a result, stable pressure resistance of the thyristor is maintained and the thyristor manufacturing yield is improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a JCR coating casserole according to an embodiment of the present invention, FIGS. 2, 3, and 4 are cross-sectional views of a thyristor element during conventional JcR coating, and FIG. FIG. 3 is a cross-sectional view of a thyristor element manufactured by the apparatus of FIG. 1: Silicon substrate, 10: Thyristor element, 5:
JCR,'I: Chuck jig, 8: Motor, 9: Fig. 1

Claims (1)

[Claims] 1) When applying bonding coating resin to the side surface of a thyristor substrate with a sigma bevel structure where the cross-sectional area of the substrate parallel to the substrate surface is the smallest at the center of the board thickness, while rotating the thyristor substrate with the surface almost vertical, . A method for manufacturing a thyristor, characterized in that the resin is applied by dropping the resin from above onto a side surface of a substrate, and then dried.