The use of Raman spectroscopy to characterize strain in strained Si and strained SiGe has been widely accepted. To use Raman spectroscopy for quantitative biaxial strain measurements, the strain shift coefficient for Si-Si vibration from strained Si (b StSi Si{Si ) and strained SiGe (b StSiGe Si{Si ) must be known. So far, b StSiGe Si{Si is commonly used to calculate strain in strained Si, which may result in inaccurate strain values. In this work, we report the first direct measurement of b StSi Si{Si by correlating highresolution X-ray diffraction and Raman spectroscopy, which yields a measured value of À784 AE 4 cm À1 . We also show that the strain shift coefficient of SiGe, b StSiGe Si{Si , is a strong function of Ge concentration (x), and follows the empirical relation: b ¼ À773:9 À 897:7x for x < 0:35.

We investigated the formation of CoSi2 for Ti capped Co on (100) Si substrate with emphasis on the Co–Ti interaction and its effect on thermal stability. A 15 nm thick Ti capping layer is shown to improve the interfacial roughness and thermal stability of CoSi2 film grown on Si substrate compared with TiN capping. The increased uniformity of silicide/Si(100) interface is speculated to result from retarded Co–Si reaction by the formation of CoTi binary phase. And the high thermal stability can be explained by the fact that the amount of Ti atoms in CoSi2 film for Ti capping is much higher than what is in TiN capping. It is likely that the surface Ti diffuses rapidly into CoSi2 grain boundaries and slows down the agglomeration process, thereby increasing thermal stability while Ti in TiN capping did not.

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