Abstract
Non-contact stress evaluation is required for nano-scale devices related to LSI and MEMS to improve their characteristics and reliability. Raman spectroscopy is known to measure surface stress of silicon without contacts and damages, but it cannot be applied to silicon-oxide(Si0_x) film that is commonly used as a passivation layer in silicon MEMS. We have proposed the stress measurement method for SiO_x, films using cathodoluminescence (CL) spectroscopy. However the CL stress measurement has a potential damaging the SiO_x, because electron beam (EB) irradiation is used for excitation of a specimen. To investigate the damage, we conducted Raman spectroscopic analysis and transmission electron microscope (TEM) observation. From Raman spectroscopic analysis, it found that stress distribution was changed at around EB irradiation spots. This change was probably caused by a structural change in SiO_x film or some damage at SiO_x/Si interface by the irradiation. And the TEM observation identified that EB irradiation produced silicon nanocrystals in SiO_x film. To measure the stress in SiO_x film using CL spectroscopy without any damages, EB irradiation condition without silicon nanocrystals generation must be specified
