A Study of Extended Defects in Silicon Crystals After Exposure to a Hydrogen Plasma

Abstract

ABSTRACTThe distribution, number density, and nature of extended defects in crystalline silicon which is exposed to plasma-generated atomic hydrogen at a temperature of 250°C are characterized by transmission electron microscopy. Cross-sectional and plan-view modes are used for these characterizations. Extended defects are typically detected in the near surface region of a < 001 > crystal and their number density may exceed 109 defects-cm2, depending on die plasma exposure time, wafer temperature, gas pressure, and power. These defects exhibit contrast features which are characteristic of small dislocation loops (> 50nm in dia) and the nature of their associated strain field is assessed by diffraction-contrast techniques. The relationship between loop-like contrast features and die so-called hydrogen-induced platelet is established by both diffraction-contrast and phase-contrast imaging techniques. The results show that loop-like and platelet-like images exhibit contrast features which are consistent with a compressive strain field and therefore it is concluded that the extended defects in this study are interstitial in nature.