Four layer semiconductor device

Claim 1

A SEMICONDUCTOR SWITCHING DEVICE HAVING FIRST AND SECOND SPACED FACES COMPRISING A FIRST REGION OF SEMICONDUCTOR MATERIAL OF ONE CONDUCTIVITY TYPE, ONE SURFACE OF SAID REGION FORMING A FIRST FACE OF THE DEVICE, A SECOND REGION OF SEMICONDUCTOR MATERIAL OF OPPOSITE CONDUCTIVITY TYPE CONTIGUOUS WITH SAID FIRST REGION AND FORMING THEREWITH A FIRST RECTIFYING JUNCTION, SAID SECOND REGION HAVING AN OUTER PORTION WHICH COMPLETELY SURROUNDS A THINNER INNER PORTION, A THIRD REGION OF SEMICONDUCTOR MATERIAL OF SAID ONE CONDUCTIVITY TYPE CONTIGUOUS WITH THE SECOND REGION AND FORMING THEREWITH A SECOND RECTIFYING JUNCTION, SAID JUNCTION HAVING AN INNER PORTION CONTIGUOUS WITH SAID THINNER INNER PORTION WHICH HAS A RELATIVELY HIGH CONCENTRATION OF UNBALANCED CHEMICAL CHARGES ON AT LEAST ONE SIDE OF THE JUNCTION AND A SURROUNDING OUTER PORTION CONTIGUOUS WITH SAID OUTER PORTION WHICH HAS A LOW CONCENTRATION OF UNBALANCED CHEMICAL CHARGES ON SAID SIDE OF THE JUNCTION, THE LATTER PORTION OF SAID JUNCTION EXTENDING TO THE SURFACE OF THE DEVICE, SAID THIRD REGION HAVING PORTIONS EXTENDING TO THE SECOND FACE OF THE DEVICE, A DISTRIBUTED FOURTH REGION OF SEMICONDUCTOR MATERIAL OF SAID OPPOSITE CONDUCTIVITY TYPE COMPRISING A PLURALITY OF REGIONS INSET INTO THE THIRD REGION TO FORM THEREWITH A DISTRIBUTED THIRD JUNCTION, SAID PLURALITY OF REGIONS HAVING A WIDTH IN AT LEAST ONE DIMENSION EQUAL TO OR SMALLER THAN THE LATERAL SPREADING DISTANCE OF MINORITY CARRIERS THROUGH THE THIRD REGION, SAID FOURTH REGION DEFINING TOGETHER WITH THE THIRD REGION THE SECOND FACE OF SAID DEVICE, AND AN OHMIC CONNECTION MADE TO THE SECOND FACE OF THE DEVICE THEREBY TO MAKE OHMIC CONNECTION TO THE PORTIONS OF THE THIRD AND FOURTH REGIONS EXTENDING TO SAID FACE, AND AN OHMIC CONNECTION TO THE FIRST REGION.