Process and design issues in a 600 V bonded wafer process

Describes a bipolar process which provides moderate voltage vertical devices and 600V lateral devices. High breakdown is achieved using relatively thin islands with no buried layer. Island thickness and bond oxide thickness are the two material parameters which have a large influence on breakdown when island doping has been optimized. Island thickness in this work was chosen to be greater than 20 microns so that there is enough island under the base of the vertical bipolars to provide a low collector resistance. The maximum thickness used was 40 microns which is about the maximum thickness through which it is practical to RIE etch to form the lateral isolation trenches. The bond and side oxide thicknesses were set at 4 microns to achieve 600V breakdown in the chosen island thickness.