A COMPARISON OF CL2 AND HBR CL2-BASED POLYSILICON ETCH CHEMISTRIES - IMPACT ON SIO2 AND SI SUBSTRATE DAMAGE/

The damage produced in thin SiO2/Si structures after plasma exposure i n Cl2-based or HBr/Cl2-based reactive ion etching environments is exam ined. The etch chemistries and parameters used were those of a poly-Si gate overetch. In this study, the damage present in the SiO2 and Si s ubstrate after these etch exposures and that remaining after a 900-deg rees-C 1 hour Ar anneal is examined for both etch chemistries. Oxide r eliability is shown to be affected even by the more benign etch, even after the annealing. On the other hand, Si substrate defects are annea led out to low levels after a 700-degrees-C 1 hour anneal for both che mistries. These defects are, however, present in numbers that are larg e enough to affect generation lifetimes either immediately after etch or at intermediate annealing temperatures.