Tensor evaluation of stress relaxation profile in strained SiGe nanostructures on Si substrate

A strained SiGe layer will be used in next-generation transistors to improve device performance along with device scaling. However, the stress relaxation of SiGe layer may be inevitable in nanodevices, because the SiGe layer is processed into nanostructure. In this study, we evaluated the stress relaxation profiles in mesa-shaped strained SiGe layers on Si substrate by electron back scattering pattern (EBSP), super-resolution Raman spectroscopy (SRRS) measurements, and finite element method (FEM) simulation. As a result, the stress relaxation profile with high spatial resolution was obtained by SRRS and EBSP measurements. The precise shear stress profiles were also obtained by EBSP measurement. Moreover, these stress profiles were reproduced by FEM simulation. The spatial resolution of EBSP and SRRS were estimated less than 100 nm. Thus, it is prospective to evaluate the precise stress relaxation profile in the sub-100 nm order devices by EBSP and SRRS measurements, respectively.