High voltage dielectric isolation SCR integrated circuit process

High voltage integrated circuit SCR's are required for applications such as cross point switching in telephone networks. This paper describes a process which produces these components in integrated form using dielectric isolation to eliminate substrate current, isolation leakage and latch-up and to achieve improved packing density. Significant characteristics of the devices produced are: breakover voltage > 250V; V
F
< 1.6v at anode current density = 100ma/mil
²
; anode current >1mA per mil
²
of chip area; r
on
< 10 ohms; gate turn off by cathode gate. Analysis and experimental results of two effects unique to dielectric isolation will be presented. One is confinement of minority carriers in a limited volume by the impenetrable oxide isolation. The other is the effect on breakdown voltage bf spreading a depletion layer through a lightly doped region and against oxide isolation and the variation of this voltage with bias on the poly silicon substrate.