The Modulation of Crystal Originated Pits by the LOCOS Process in 0.25μm SRAM Technology

摘要

Crystal originated pits (COPs) were observed onpatterned silicon wafers after local oxidation of silicon (LOCOS)process in 0.25μm static random access memory (SRAM)technology. Most COPs were found located in the narrow activeregion. Design of experiments revealed that the thickness of padoxide, nitride, and field oxide modulate the density of COPs. Thecalculation of hydrostatic stress introduced in the LOCOSprocess showed that the stress generated in the active regioncorrelates with the density of COPs. No correlation of yield tothe COP density was found.