Investigation of In Situ Boron-Doping in SiGe Source/Drain Layer Growth for PMOS Devices

Abstract

Embedded SiGe (eSiGe) source/drain (S/D) was studied to enhance PMOS performance. Detailed investigations concerning the effect of GeH4and B2H6gas flow rate on the resultant Boron-doping of the SiGe layer (on a 40 nm patterned wafer) were carried out. Various SiGeB epitaxial growth experiments were realized under systematically varying experimental conditions. Key structural and chemical characteristics of the SiGeB layers were investigated using Secondary Ion Mass Spectroscopy (SIMS), nanobeam diffraction mode (NBD), and Transmission Electron Microscopy (TEM) itself. Furthermore,Ion/Ioffperformances of 40 nm PMOS transistors are also measured by the Parametric Test Systems for the semiconductor industry. The results indicate that the ratio between GeH4and B2H6gas flow rates influences not only the Ge and Boron content of the SiGeB layer, but also the PMOS channel strain and the morphology of the eSiGe S/D regions which directly affect PMOS performance. In addition, the mechanism of Boron-doping during SiGe layer growth on the pattern wafer is briefly discussed. The results and discussion presented within this paper are expected to contribute to the optimization of eSiGe stressor, aimed for advanced CMOS devices.