DISLOCATIONS GENERATION IN SELECTIVE AND NON-SELECTIVE SiGe EPITAXY

摘要

In this paper, we investigate the influence of the isolation structure (Shallow Trench Isolation versus LOCal Oxidation Structure) on dislocation nucleation for a non-selective epitaxial growth. In our experimental conditions, no major difference is found. On the other hand, the reduction of misfit dislocation density with a selective epitaxial growth versus non-selective epitaxial growth is studied experimentally. The experiments were performed on Si_(1-x)Ge_x layers with x = 0.13 grown on LOCOS substrates. The misfit dislocations were detected by optical microscopy, TEM, AFM, and X-ray diffraction. Our results demonstrate the huge superiority of SEG in terms of critical thickness. This difference between SEG and NSEG allow us to clearly identify the major cause of stress relaxation, which is the polycrystalline silicon at the edges of the monocrystalline areas in the case of non-selective epitaxy.