CBED and FE Study of Thin Foil Relaxation in Cross-Section Samples of Si /Si1-xGex and Si /Si1-xGex /Si Heterostructures

In order to determine residual stress/strain fields in CMOS devices and validate tools used to quantify the strain field, we first studied residual strains in Si/Si_1-xGe_x and Si/Si_1-xGe_x/Si TEM samples. Because of sample thinning for TEM observations, elastic relaxation occurs and modifies the initial stress present in the bulk sample. Nevertheless, if the main parameters which play a role on the elastic relaxation process can be determined, we show that it is possible to reproduce from FE and diffraction simulations the complex profile of the HOLZ lines observed on experimental CBED patterns which makes possible the determination of the initial stress state.