X-ray diffraction measurements of strained and relaxed SiGe epitaxial layers on Si

SiGe epitaxy is being introduced into Si integrated circuit technology for high-frequency low-power applications. This new development brings to the industry a requirement for new techniques to characterise the deposited layers. High resolution X-ray diffraction techniques have high measurement precision and are non-destructive, and thus are well suited to the task. We describe examples showing the high sensitivity of X-ray diffractometry to SiGe layer strain state, thickness, composition and profile. Additionally we use X-ray diffraction space mapping and single crystal topography to gain information about the relaxation mechanisms occurring in layers deposited to form SiGe virtual substrates.