Characterization of internal gettering of copper in the vertical direction of p-type silicon wafer

We determined characteristics of internal gettering of copper in the vertical direction of p-type silicon wafer. Bulk micro-defects (BMDs) caused by oxygen precipitation and the gettering efficiency of Cu along the vertical direction from the surface into the bulk were investigated for Si wafers with and without rapid thermal annealing (RTA) process. Based on scanning infrared microscopy, secondary ion mass spectrometry, and local etching results, the density of BMDs in Si wafers with RTA process was higher than that in Si wafer without RTA process. Depth profile of Cu concentration was strongly related to the BMD density profile in the vertical direction. According to the transmission electron microscopy analysis, Cu impurities were trapped at BMDs through precipitation of copper silicides. It is proposed that the RTA process can improve the internal getterig efficiency of copper in the vertical direction of p-type silicon wafer.