Wafer Edge RF LNR Yield Improvement in Oxide Etch Applications

In this paper, we are introducing a New Design Hot Edge Ring (NHER) to improve wafer edge yield. Lower yield at wafer edge has been a well-known phenomenon in wafer fabrication. Smaller die devices (typically more than 30K per wafer) are particularly susceptible to this phenomenon. Wafer yield is one, if not the most critical metric for wafer manufacturers and a few factors contribute to it, including defects, under/over etch and poor edge rounding. Hot Edge Ring (HER), a typical process kit used in Oxide chambers, serves to provide a buffer zone around the wafer, prevent cracks and defects from propagating to the edge, improves edge rounding and helps focus plasma onto the wafer. From our study, we found that by optimizing the thickness of the HER, wafer edge yield can be improved by 2% to 3%.