A FINE PATTERN GTO THYRISTOR FABRICATED USING A SELF-ALIGNED PROCESS

GTO thyristors with a 2 cm(2) active area and small rectangular 40 4 0 mu M emitters were fabricated using a specially developed self-align ed process based entirely on reactive ion etching RIE, technology. Eac h device consists of 176 1 mm(2) segments containing 100 individual em itters. The devices were electrically evaluated and compared to standa rd, wet etched mesa, GTO devices of comparable size having 3000 200 mu m large emitters. Simulations were carried out to analyse specific features of the new devices. In particular the influence of the surfac e quality on the gate trigger current and on-state voltage was investi gated It was demonstrated that it is possible to reduce significantly the GTO unit cell dimensions without sacrificing the yield. 23% of the cm(2) devices out of a lot containing 50 devices could be accepted wi thout repair while the overall segment yield was 97%. The dynamic perf ormance of the devices under both snubbered and snubberless conditions compares well to that of the reference devices.