Efficient two-dimensional multilayer process simulation of advanced bipolar devices

Abstract

In order to study advanced bipolar transistors including several polysilicon layers and U-groove isolation, a dedicated two-dimensional multilayer process simulator, IMPACT4, has been developed. From the simulation point of view, the new aspects introduced by these devices, namely the multilayer and non planar characteristics, are carefully taken into account by the program. Especially, the algorithmic procedure solving the dopant redistribution at interfaces is discussed. The application to a self-aligned polysilicon emitter bipolar transistor is presented. Intrinsic and extrinsic bases formation has been studied, it has been demonstrated that the segregation phenomenon greatly affects bases connection. Typical 2-D effects induced by the walled emitter configuration, such as lateral base thinning are also detailed.