CATHODOLUMINESCENCE STRESS ANALYSIS OF STRESSED/UNSTRESSED SILICA-BASED SEMICONDUCTOR DEVICES

摘要

During the manufacturing process, residual stresses of significant magnitude may remain stored within metal oxide semiconductor (MOS) devices. These residual stress fields can dramatically hinder the electronic properties of Si/SiO_2 electro-optical devices. In this study, the analysis of residual stress distributions in MOS devices was made according to a piezo-spectroscopic approach applied to selected cathodoluminescence bands arising from optically active defects in silica glass. The spectral position of some of these bands was found to be clearly linked to stress by a linear relationship, the proportionality constant between spectral band shift and applied/residual stress being referred to as the piezo-spectroscopic (PS) coefficient. In this paper, the PS coefficient of silica was first experimentally determined using the microscopic stress field located at the tip of a Vickers indentation crack. In this calibration experiment, a special stressfree silica sample was used. Then, two-dimensional stress maps were collected on actual Si/SiO_2 MOS devices ahead of a crack tip.