Tiny Pitts are the Yield Major Killer Caused by Metal Contamination in Wet Bench Cleaning

In this paper, we analyzed the contamination of heavy metals on process wafers before gate oxide deposition. A lot of mushrooms-like defects were easy found in wafer edge. And at that time, a lot of pits also can be found in active region of device, as the silicon substrate had been with heavy metallic contamination. TEM and EDS analysis were used to examine the mushrooms type defects and pits defects. A reasonable mechanism was proposed to check the problem stage of manufacturing process