Self-aligned channel stop.

摘要

In a semiconductor structure having two highly and similarly doped, e.g., P+ type, regions (26,30) embedded in close juxtaposition in a trench-isolated N type silicon mesa (22), N+ channel stops (40,42) embedded in the N type mesa between the P type regions, are provided. The channel stops are self-aligned to the walls of trench to arrest charge leakage between the P type regions due to parasitic transistor action along the trench wall. The P type regions may constitute two resistors, the emitter and collector of a lateral PNP transistor, etc. The dopant concentration in the channel stops is about one to two orders of magnitude higher than that in the N type silicon. A process of forming such channel stops introduces N type dopant into the exposed silicon followed by an anneal step to laterally diffuse the dopant into the silicon body. The exposed silicon is etched forming a deep trench which delineates silicon mesa having at a section of the peripheral portion thereof a shallow and highly N doped region.