ELIMINATION OF WALKOUT IN HIGH VOLTAGE TRENCH ISOLATED DEVICES

Walkout in high voltage trench isolated semiconductor devices is inhibited by applying a voltage bias signal directly to epitaxial silicon surrounding the device. Voltage applied to the surrounding epitaxial silicon elevates the initial breakdown voltage of the device and eliminates walkout. This is because voltage applied to the surrounding epitaxial silicon reduces the strength of the electric field between the silicon of the device and the surrounding silicon. Specifically, application of a positive voltage bias signal to surrounding epitaxial silicon equal to or more positive than the most positive potential occurring at the collector during normal operation of the device ensures that no walkout will occur.