Degradation Phenomena of Planar Si Devices Due to Surface and Bulk Effects

Planar devices of almost every producer show to some extent serious degradation failures under heavy work conditions. A collector base voltage test at high temperature inverts often the n+-collector surface into a p-layer. High collector leakage currents are resulting. An emitter-base cut off-test at a reverse current of some mA destroys locally the emitter base junction at its surface. A strong decrease of the current amplification factor is resulting. Both failure mechanisms are analysed, some technological solutions to these problems are given.