Delta Doping in Si and SiGe by LP(RT)CVD

Abstract

Sharp profiles of boron were prepared by Low Pressure (Rapid Thermal) Chemical Vapor Deposition (LP(RT)CVD). Two different approaches for the delta doping were used. In the first case the dopants were incorporated into the growing film. The process was kinetically controlled. By this way B-delta-layers with a steepness of 1.7 nm/decade were measured by Secondary ion mass spectrometry (SIMS) for the profiles prepared. In the second case the doping was performed during an interruption of layer growth. The process was controlled by the surface adsorption equilibrium of dopants. Using this regime B-delta-layers of 1 monolayer and with a steepness of 1.4 nm/decade were obtained in SiGe. The values of the estimated steepness represent an extremely sharp profile for a CVD process. Structural properties of the delta-doped layers were investigated using cross sectional transmission electron microscopy (XTEM). The steepness estimated by SIMS was compared with high depth resolution spreading resistance (SR) measurements which detect the electrical active boron only.