The modulation of crystal originated pits by the LOCOS process in 0.25 mu m SRAM technology

Crystal originated pits (COPs) were observed on patterned silicon wafers af ter local oxidation of silicon (LOCOS) process in 0.25 mm static random acc ess memory (SRAM) technology. Most COPs were found located in the narrow ac tive region. Design of experiments revealed that the thickness of pad oxide , nitride, and field oxide modulate the density of COPs. The calculation of hydrostatic stress introduced in the LOCOS process showed that the stress generated in the active region correlates with the density of COPs. No corr elation of yield to the COP density was found. (C) 1999 The Electrochemical Society. S1099-0062(99)01-093-7. All rights reserved.