Stress Metrology : The challenge for the next generation of engineered wafers

Abstract

ABSTRACTRaman spectroscopy is a powerful and versatile technique for stress measurements in complex stacks of thin crystalline layers at macroscopic and microscopic scales. Using such a technique we show that thick SiGe layers epitaxially grown using graded buffer method are fully relaxed (>95%) at a macroscopic scale but exhibit a small strain modulation at a microscopic scale. For the first time we report the results of Raman micro-mapping of stress distribution in SGOI wafers produced by Smart Cut™ technology. We conclude that Smart Cut™ is a unique method to manufacture the next generation of engineered wafers that can combine strained and/or relaxed SiGe alloys, Si and Ge films, while keeping their initial strain properties at both scales. It is important to develop Raman spectroscopy tool for in-line process control in fabrication of strained Silicon On Insulator (sSOI) wafers.