Characterization of Si/SiGe Strained-Layer Superlattices Grown by an Ultrahigh Vacuum/Chemical Vapor Deposition Technique

Abstract

High-resolution double-crystal X-ray diffraction and cross-sectional transmission electron microscopy were used to characterize the Si/SiGe strained-layer superlattices grown by the ultrahigh vacuum/chemical vapor deposition (UHV/CVD) system. A dynamical X-ray simulation was employed to analyze the experimental rocking curves. Good matches between the experimental rocking curves and the simulated ones demonstrate that the high quality Si/SiGe strained-layer superlattices with abrupt interface and excellent thickness and composition uniformity have been achieved. Thickness uniformity was further confirmed by the cross-sectional transmission electron microscopy. In addition, high-resolution double-crystal X-ray diffraction was proven to be a powerful technique for determining the doping level and the thickness of heavily doped contact layer in Si/SiGe device structures prior to further processing. Good wafer-to-wafer uniformity can be simultaneously achieved by the UHV/CVD technique; as a result, the UHV/CVD technique is readily applicable to manufacturing.