PLASMA CHARGE MONITOR OF In-Situ PRE-SPUTTER ETCH AND METAL DEPOSITION PROCESS IN A SPUTTER SYSTEM

摘要

Plasma induced charging damage caused by pre-sputter etch and metal PVD sputter have been investigated using un-patterned oxide wafer by non-contacting corona-biased measurements. The surface voltage (Vs) mapping has shown the distinctive charging fingerprint of different etch conditions. With the confining magnets, the Vs mapping shows a very high positive charging and a non-uniform plasma. Without the magnets, the Vs mapping indicates a very uniform plasma, and the charging is reduced by 80%. Etch rate uniformity, oxide interface trap density and E-tunnel dependence on the surface plasma charging has been revealed. The oxide charging as a function of Ti/TiN deposition time and power have been studied. The results demonstrate that Ti sputter increases oxide charges. However, the charging level is not significant and it can be corrected by the next step of the TiN sputtering, which can be explained by nitrogen incorporation into the oxide during plasma-assisted film deposition.