Strain Studies of Silicon-Germanium Hetero-Epitaxial Layer by X-ray Reciprocal Space Mapping

摘要

Recently, single crystal Si channels in metal-oxide-semiconductor field effect transistors (MOSFETs) have been replaced with stained Si, SiGe and Ge channels in order to enhance electron or hole mobility in channel direction. Therefore, it is a significant issue to evaluate the strain relaxation and lattice mismatch in these strained silicon-germanium hetero-epitaxial layers. However, two-dimensional reciprocal space mapping (2D-RSM) employing the triple axis X-ray diffractometry have been considered to be a powerful technology to characterize the strain status of these kinds of materials. In this article, we describe the principle of 2D-RSM, the optic components in triple axis X-ray diffractometry, experimental procedures in detail, the principle of strain calculation, and finally illustrate the experimental results of a variety of strained silicon-germanium hetero-epitaxial layers using two-dimensional reciprocal space mapping technology.