Integrated gate assisted turn-off, amplifying gate thyristor, and a method for making the same

Claim 1

A method of making an integrated amplifying gate thyristor with gate assist turn-off capability comprising the steps of: A. providing in a semiconductor body having first and second opposed major surfaces impurities to form in the body a main thyristor of four impurity regions of alternate type conductivity disposed alternately through the body between the major surfaces with a PN junction between each region, with one intermediate region adjoining the first major surface, the two impurity regions adjoining the first and second major surfaces being cathode-emitter and anode-emitter regions, respectively, the two intermediate impurity regions adjoining the cathode-emitter and anode-emitter regions being cathode-base and anode-base regions, respectively, and the cathode-base region adjoining the first major surface adjacent the cathode-emitter region; B. providing in the semiconductor body an impurity to form in the body a pilot thyristor of said cathode-base, anode-base and anode-emitter regions of the main thyristor and at least one additional impurity region adjacent to and spaced from the cathode-emitter region of the main thyristor of conductivity-type to form a PN junction with said cathode-base region and a separate cathode-emitter region for the pilot thyristor; C. providing in the semiconductor body an impurity to form in the body a diode of said cathode-base region of the thyristors and at least one additional impurity region being a cathode region adjacent to and spaced from the cathode-emitter regions of the main and pilot thyristors; D. selectively masking against a radiation means portions of the first major surface of the semiconductor body adjoining the main and pilot thyristor, while leaving exposed portions of the first major surface adjoining the diode; E. selectively irradiating the diode in the semiconductor body with said radiation means through said masking to reduce the current gain of the common cathode-base region at the diode to less than the ratio of I FB /I g , where I FB is the forward anode current triggering the diode to function as a thyristor in the low impedance conducting state, and I g is a specified gate assist turn-off current to turn-off the main thyristor; F. positioning cathode and anode electrodes on said first and second major surfaces, respectively, to make ohmic contact with the cathode-emitter region of the main thyristor and the common anode-emitter region of the main and pilot thyristors; G. positioning a gate electrode on said first major surface to make ohmic contact with the common cathode-base region adjacent to and spaced from the cathode-emitter region of the pilot thyristor and the cathode region of the diode; and H. positioning a floating electrode on said first major surface adjacent to and spaced from the gate electrode to make ohmic contact with the common cathode-base region between the thyristors and the cathode-emitter region of the pilot thyristor.

Claim 2

A method of making an integrated amplifying gate thyristor with gate assist turn-off capability comprising the steps of: A. providing in a semiconductor body having first and second opposed major surfaces impurities to form in the body a main thyristor of four impurity regions of alternate type conductivity disposed alternately through the body between the major surfaces with a PN junction between each region, with one intermediate region adjoining the first major surface, the two impurity regions adjoining the first and second major surfaces being cathode-emitter and anode-emitter regions, respectively, the two intermediate impurity regions adjoining the cathode-emitter and anode-emitter regions being cathode-base and anode-base regions, respectively, and the cathode-base region adjoining the first major surface adjacent the cathode-emitter region; B. providing in the semiconductor body an impurity to form in the body a pilot thyristor of said cathode-base, anode-base and anode-emitter regions of the main thyristor and at least one additional impurity region adjacent to and spaced from the cathode-emitter region of the main thyristor of conductivity-type to form a PN junction with said cathode-base region and a separate cathode-emitter region for the pilot thyristor; C. providing in the semiconductor body an impurity to form in the body a diode of said cathode-base region of the thyristors and at least one additional impurity region being a cathode region adjacent to and spaced from the cathode-emitter regions of the main and pilot thyristors; D. selectively masking against a radiation means portions of the first major surface of the semiconductor body adjoining the main and pilot thyristor, while leaving exposed portions of the first major surface adjoining the diode; E. selectively irradiating the diode in the semiconductor body with said radiation means through said masking to reduce the current gain of the common cathode-base region at the diode to less than the ratio of I FB /I g , where I FB is the forward anode current triggering the diode to function as a thyristor in the low impedance conducting state, and I g is a specified gate assist turn-off current to turn-off the main thyristor; F. positioning cathode and anode electrodes on said first and second major surfaces, respectively, to make ohmic contact with the cathode-emitter region of the main thyristor and the common anode-emitter region of the main and pilot thyristors; G. positioning a gate electrode on said first major surface to make ohmic contact with the common cathode-base region adjacent to and spaced from the cathode-emitter region of the pilot thyristor and the cathode region of the diode; and H. positioning a floating electrode on said first major surface adjacent to and spaced from the gate electrode to make ohmic contact with the common cathode-base region between the thyristors and the cathode-emitter region of the pilot thyristor.