Rapid Annealing Factor for Bipolar Silicon Devices Irradiated by Fast Neutron Pulse

Abstract

A pulse of fast neutrons induces Frenkel defects in bipolor transistors and ICs which degrade their performance. Most of the defects are rapidly cured and disappear. The parameter used to quantify this transient phenomenon is called the annealing factor and it is defined in terms of the common emitter current gain. This paper develops a mathematical model of the annealing factor based on the physics of the generation and annealing of the defects which agrees well with experimental data (Ref 1 and 2). It models the annealing factor both during and after a time-varying finite duration neutron pulse. Electron density is the most important factor governing the annealing rate, and the sources of electron density such as neutron and gamma-ray ionization are discussed. The model is incorporated into SYSCAP II circuit analysis codes for prediction of circuit transient response. Several computed results are given.