Improvement of thermal stability of boron in SiGeB/Si heterostructure by stress compensation

Abstract

AbstractThe thermal diffusion of boron in the SiGe/Si heterostructure during thermal treatment in inert gas was investigated. It was proved experimentally that in the SiGeB/Si structure where the boron concentration in the SiGe layer was higher than that in the Si underlayer, the redistribution of boron from the SiGe layer to the Si layer was less than that in the Si mono‐layer. Also, the thermal stability of boron improved and thep+n junction was shallower than that in the Si monolayer.To clarify this symptom and to use it in the device process, the equation for the boron diffusion in the hater ostructure structure was derived using the chemical potential. the theoretical equation indicated that boron diffused from the Si layer to the SiGe layer in such a manner that the crystalline strain due to the introduction of Ge was compensated. the experimental results were supported by this theoretical prediction. In addition, it was clarified that the theoretical equation was justified quantitatively by computer simulation.A new method of forming a shallow p+n junction using the SiGeB/Si heterostructure was proposed based on a theoretical equation, and the guiding principle for the optimization of the process was clarified.