Etch-induced damage in single crystal Si trench etching by planar inductively coupled Cl-2/N-2 and Cl-2/HBr plasmas

In this study, 0.3-0.5 mu m deep and 0.3 mu m wide silicon trenches were et ched using Cl-2/10%-N-2 and Cl-2/50%-HBr inductively coupled plasmas, the p hysical and electrical defects remaining on the etched silicon trench surfa ces and the effects of various annealing and oxidation on the removal of th e defects were studied. High resolution transmission electron microscopy an d capacitance-voltage techniques were used to investigate the physical and electrical defects, respectively. Physical defects were found on the silico n trench surfaces etched in both Cl-2/10%-N-2 and Cl-2/50%-HBr. The most de nse defects were found near the trench button edge, lesser dense defects we re found at the trench bottom, and the least dense defects were found at th e trench sidewall. The silicon etched in Cl-2/50%-HBr showed more physical defects compared to that etched in Cl-2/10%-N-2. Thermal oxidation of 20 nm at temperatures up to 1100 degrees C alone appears not to remove the defec ts formed on the etched silicon trenches for both of the etch conditions. T o remove the defects, an annealing at temperatures higher than 1000 degrees C in N-2 for 30 min appears to be required. (C) 1999 Elsevier Science S.A. All rights reserved.