# US 4,394,677 A · Thyristor for low-loss triggering of short impulses with Schottky contact to control gate electrode

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- Number: US 4,394,677 A
- Document ID: US4394677A
- Status: Granted
- Kind: A
- Application number: 06/182,655
- Filed: 1980-08-29
- Granted: 1983-07-19
- Earliest claimed: 1980-01-16
- Assignees: BBC Brown, Boveri & Company, Limited
- Inventors: Andre Jaecklin
- Web page: https://patentgrep.com/patent/US4394677A

## CPC

- H10D 18/221: {having amplifying gate structures, e.g. cascade configurations}
- H10D 18/60: Gate-turn-off devices
- H10D 84/135: {the built-in components being diodes}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A thyristor for low-loss triggering of short impulses, including a main thyristor formed of four alternating zones of opposite conductivity type including a cathode emitter, a cathode base, an anode base and an anode, with a portion of the cathode base emerging to a cathode-side surface and serving as a gate; an integrated auxiliary thyristor provided for improving current rise time upon main thyristor ignition between the gate and the cathode emitter of the main thyristor; and an integrated diode provided for shortening the turn-off time of the main thyristor when ending current conduction therethrough; wherein the integrated diode is implemented as a Schottky contact which injects virtually no electrons into the cathode base under normal operating conditions.

## Claims

### Claim 1

A disc-shaped thyristor device comprising:
a main thyristor formed of four alternating zones of opposite conductivity type including an n.sup.+ -doped cathode emitter, a p-doped cathode base, a n-doped anode base and a p-doped anode, wherein a portion of the cathode base emerges to a cathode-side surface and serves as a gate;
an integrated auxiliary thyristor provided for improving current rise time upon main thyristor ignition, said auxiliary thyristor comprising an n.sup.+ -doped region and p.sup.+ -doped secondary control region formed between the gate and the cathode emitter of the main thyristor; and
an integrated diode provided for shortening the turn-off time of the main thyristor during turn-off of current conduction therethrough, said integrated diode comprising a Schottky contact formed between the gate and the cathode emitter on said cathode base of said main thyristor, said Schottky contact electrically connected to said gate by means of a metallization.

### Claim 2 (depends on 1)

A thyristor according to claim 1, further comprising:
said Schottky contact formed by a surface area of said p-cathode base coated with a metal.

### Claim 3 (depends on 1)

A thyristor according to claim 1, further comprising:
said Schottky contact arranged in a laterally structured p-cathode base between said gate and a cathode emitter.

### Claim 4 (depends on 2)

A thyristor according to claim 2, further comprising:
the metal of the Schottky contact selected from the group consisting of aluminum, gold, molybdenum and tungsten.

### Claim 5 (depends on 1)

A thyristor according to claim 1, further comprising:
said Schottky contact formed by a surface area of said p-cathode base coated with an alloy.

### Claim 6 (depends on 5)

A thyristor according to claim 5, further comprising:
said alloy of the Schottky contact consisting of PtSi.

### Claim 7 (depends on 2, 5)

A thyristor according to claim 2 or claim 5, further comprising:
the Schottky contact covered by a layer of a high electrical conductivity.

### Claim 8 (depends on 2, 5)

A thyristor according to claim 2, or claim 5, further comprising:
the surface concentration in the p-cathode base is lower than 5.multidot.10.sup.17 /cm.sup.3 in the area of the Schottky contact.

### Claim 9 (depends on 2, 5)

A thyristor according to claim 2, or claim 5, further comprising:
the surface concentration in the p-cathode base is lower than 5.multidot.10.sup.16 /cm.sup.3 in the area of the Schottky contact.

### Claim 10 (depends on 1)

A thyristor according to claim 1, further comprising:
said Schottky contact having a peripheral edge;
a protective ring of polysilicon provided around said peripheral edge for the reduction of leakage current.

### Claim 11 (depends on 1)

A thyristor according to claim 1, further comprising:
said cathode emitter symmetrically arranged around said gate; and,
said n.sup.+ -region of the auxiliary thyristor having at least one sector-shaped recess in which said Schottky contact is arranged.

### Claim 12 (depends on 11)

A thyristor according to claim 11, further comprising:
said cathode emitter divided into sectors radially symmetrical with respect to said gate;
said Schottky contact formed by a surface area of said p-cathode base coated with a metal or an alloy, said p-cathode base in the area of said Schottky contact having a surface concentration lower than 5.times.10.sup.17 /cm.sup.3 ; and
said p.sup.+ -region of said integrated auxiliary thyristor adapted for use as a secondary control electrode and having branches running in a radial direction between respective radial edges of adjacent cathode emitter sectors.