| 摘要 |
<p>A thyristor semiconductor switching device is self-protected against forward voltage breakover by a localized avalanche voltage breakover zone which ensures that forward voltage breakover will occur in a known region of the device where a non-destructive, controlled turn-on process can be initiated. The localized avalanche voltage breakover zone in one form includes a recess extending into the P-base region of the device to locally increase the avalanche multiplication factor. In one embodiment, the recess extends only partly through the P-base layer. In another embodiment, the recess extends completely through the P-base layer. In another form, the avalanche voltage breakover zone is planar and comprises a portion of the N-base layer extending through the P-base layer such that a portion of the PN junction between the P-base and the N-base has a radius of curvature and such that a gap is defined between opposed portions of the P-base layer. In the case of the recess the surface-adjacent region of the recess comprises a field-containing layer of P conductivity type, but doped higher in concentration than the P-base region. Thus the field-containing layer comprises an electrical extension of the P-base region. The thyristor has a blocking PN junction having a depletion region extending into the field-containing layer. The thickness of the field-containing region is greater than the depletion layer width in the field-containing layer under device forward blocking conditions. In the case of the curved PN junction, the surface-adjacent region of the N-base extending portion comprises a field-containing layer of P conductivity type doped higher in concentration than the P-base region and comprising an electrical extension thereof. As a result, in either case no electric field lines terminate at the surface of the field-containing layer. No surface passivating film is required.</p> |
