JPH021989A - Switching diode of high breakdown voltage - Google Patents

Abstract

PURPOSE:To make the polarity of a heat dissipating plate positive using an N-type semiconductor substrate so as to obtain a semiconductor device, possessed of a polarity opposite to that of a conventional one, of a P<+>NN<+> structure by a method wherein an impurity layer penetrating vertically through the semiconductor substrate, a high concentration impurity layer possessed of a conductivity type opposite to that of a substrate formed on one principle face of a silicon substrate, a high concentration impurity layer of the same conductivity type as that of a substrate selectively formed on the opposite principal face of the above silicon substrate, and metal electrodes fixed to those high impurity layers are provided. CONSTITUTION:An N-type semiconductor substrate 1 has a specific resistance of 40OMEGA or so and a thickness of 200mum or so. A P-type insulating layer 2 is selectively formed through a planar diffusion method, performed onto the semiconductor substrate 1 from both the faces, so as to penetrate vertically through a silicon substrate. Next, a P<+> high concentration impurity layer 3 is formed from one primary face of the semiconductor substrate 1. A junction is 20mum or so in depth. Then, an N<+> high concentration impurity is formed from the other primary face of the semiconductor substrate 1. The junction is 10mum or so in depth. Next, metal electrodes 5 and 6 are formed through evaporation. By these processes, a diode, which is very similar to a conventional one and whose electrode polarity is opposite to that of it, can be obtained and has an advantage in application.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the structure of a high voltage switching diode using a planar junction.

Conventional technology CC East, the structure of a switching diode using a planar junction is N"NP'" or P"))N" structure or
The breakdown voltage is determined by the junction curvature in the P+ junction or the PN+ junction (see FIGS. 3 and 4).

Also, when mounting these chips on a heat sink, the planar joint is mounted in the opposite direction to the mounting surface, so in the case of N"N P"fMjb, the N+ surface becomes the cathode, and P" In the case of a PN+ structure, the P+ surface becomes the anode.

Problems to be Solved by the Invention In the Brehner diode of the conventional structure described above, the polarity of the heat sink is determined by the conductivity type of the conductor J and the plate H.
Therefore, it was not possible to manufacture semiconductor devices with heat sinks having different polarities using the same semiconductor substrate. That is,
When an N-type substrate is used, the polarity of the heat sink becomes a cathode, and the heat sink substrate cannot be used as an anode.

Therefore, in order to obtain a semiconductor device with reverse polarity, it is necessary to use semiconductor substrates of different conductivity types, which is a constraint on the design of the semiconductor device.

The present invention has been made in view of the above-mentioned conventional situation,
Therefore, an object of the present invention is to provide a novel high-voltage switching diode that makes it possible to solve the above-mentioned problems inherent in the conventional technology.

Differences between the invention and the prior art In contrast to the conventional one-toner diode described above, the present invention can provide semiconductor devices with different polarities using the same semiconductor substrate.

Means for Solving the Problems In order to achieve the above object, a high voltage switching diode according to the present invention includes an impurity layer that vertically penetrates a semiconductor substrate, and an impurity layer formed on one main surface of a silicon substrate opposite to the substrate. A high concentration impurity layer having a conductivity type, a high concentration impurity layer having the same conductivity type as that of the substrate selectively formed on the opposite main surface of the silicon substrate, and a metal electrode fixed to each high impurity layer. It is composed of:

EXAMPLES Next, the present invention will be described with reference to the drawings for its preferred embodiments.
I will explain it specifically.

No. 114 is a longitudinal section 1r+ showing the first embodiment according to the present invention.
i l].

To clarify the 11th At-, reference number 1 indicates an N type soil fern body substrate; rz shi, 31. N-type semiconductor substrate 1 has a resistivity of approximately 40
The insulating layer 2 of Ω is approximately 20U7Lm.
It is selectively formed by the 1tn2 method, and four holes are passed through the silicon to the left on the east face of the board.

Next, a P+1 degree non-contour layer 3 is formed from one main surface of the semiconductor substrate 1. The joining depth is approximately 21) 8 stories.

Next, a pure layer 4 with a high concentration of N1 is formed on the opposite side of the conductor JS plate 1 (from 11. The junction depth is about 1O) lIII
It is.

Metal electrodes 5 and 6 are then formed by vaporization.

FIG. 5 shows a semiconductor chip according to the present invention mounted on a heat sink, the lead wires 3') cut off, and then sealed with resin.

In the embodiment described above, an N-type conductor is used as the semiconductor substrate 1, but it is also possible to use a P-type semiconductor instead.

FIG. 2 is a longitudinal sectional view showing a second embodiment of the present invention.

In FIG. 2, in the second embodiment, two P"NN" diodes are formed in parallel on the same -N substrate, and the P+ bases and Ill of both are electrically connected with a common metal electrode. Therefore, the P,000 base layer is made a common ground.

As described in detail, according to the present invention, by using an N-type semiconductor substrate, the polarity of the heat sink becomes an anode, and it is possible to obtain a semiconductor device having a P''NN+ structure with a polarity opposite to that of the conventional semiconductor device.

On the other hand, in order to obtain a semiconductor device with the same polarity as above using the conventional method, a P-type semiconductor substrate is used, resulting in a +PN" structure.

The corresponding semiconductor device with anti-χ polarity is N4NP.
Because of the structure, the semiconductor device according to the present invention has very similar electrical characteristics.l) 1%g
In the case of a conventional structure using a substrate, the electrical characteristics will be different from the above. This is because the mobility of carriers in the semiconductor is different between a P-thick substrate and an N-type substrate.

Therefore, according to the present invention, the polarity of the electrodes is opposite and the electrical level is 1? A diode with very similar properties was obtained, and it is suitable for device applications.
becomes.

Also, in terms of the price of rtn, N-type substrates are better1).
It is manufactured from Jk board and is cheaper.
Using the N Il'l, J5 board has the advantage that a semiconductor device can be provided at a lower cost.

=1, ,I: Brief explanation of 4 sides 1st [71 is a vertical cross-sectional view showing the first embodiment according to the present invention (FJ"NN+ structure), 21M is a longitudinal cross-sectional view showing the second embodiment according to the present invention Figure 3 is a vertical cross-sectional view showing the state when the large conductor according to the present invention is sealed in a case, and Figures 1 and 1 are vertical cross-sectional views of the structure of a conventional device of this type. figure(
Figure 5 shows a conventional device of this kind;
FIG. 4 is a vertical cross-sectional view of the structure of No. 4 ([ke PN+ structure)].

1... N-type semiconductor substrate, 2... P-type insulating layer, 3...
・P+ base layer, 4...N+ base layer, 5.6...
Metal electrode, 11]...Silicon chip, 11...
Metal heat sink! 3... Dangerous wire, 14... Resin,
15... Lead, 21... N-type semiconductor substrate, 23...
...P "base layer, 24...N" base layer, 2526
...Metal electrode, 11...P-type semiconductor substrate, 31...
・N+Heath layer, 34...P+base layer, 35.36
...Kuragen electrode diagram

Claims (1)

[Claims] a silicon substrate of one conductivity type having a high resistivity (40 Ω cm or more); an impurity layer of the opposite conductivity type to the silicon substrate through which a diffusion layer penetrates in the vertical direction of the silicon substrate; a high concentration impurity layer formed and having a conductivity type opposite to that of the silicon substrate; a high concentration impurity layer selectively formed on the opposite surface of the silicon substrate and having the same conductivity type as the silicon substrate; and the two high concentration impurity layers. 1. A high voltage switching diode having metal electrode layers formed thereon, the side of the high concentration impurity layer having a conductivity type opposite to that of the silicon substrate being grounded for the semiconductor device.