In-Situ HCl Etching and Selective Epitaxial Growth of B-doped Ge for the Formation of Recessed and Raised Sources and Drains

Abstract

The aim being the integration of either recessed or raised Ge:B Sources and Drains(S/Ds), we have studied the growth kinetics and the insitu boron doping of Ge in Reduced Pressure- Chemical Vapour Deposition. The Ge growth rate at 400ºC, 60 Torr on blanket Si(001) is lower when adding HCl to GeH4. The B atoms concentration increases linearly with the F(B2H6)/F(GeH4) mass flow ratio (maximum: 3.5x1019cm3). 20% to 40% of (almost all) the B atoms are electrically active in Ge:B layers grown at 400ºC (subsequently annealed at 750ºC under H2 for 10 minutes). The macroscopic degree of strain relaxation R of as grown Ge layers increases slowly from 92% up to 100% as the Ge layer thickness increases. We have also studied the kinetics of the insitu HCl etching at 20 Torr of recess in the Si active regions of patterned wafers.