In-Line Metrology Sensitivity Analysis on Multiwire Sliced Wafers

27th European Photovoltaic Solar Energy Conference and Exhibition; 1010-1013
In this paper we studied the TTV (Total Thickness Variation) dependence on different metrology setups. Typical wafers cut by multi-wire saw show maximum thickness on one edge and minimum thickness on the opposite one. TTV is mainly due to the thickness of the 4 wafer edges, hence sensor locations and edge exclusions are decisive in TTV measurements. In this article we present a comparison of different TTV values measured by sensors located in different positions relative to the lateral edges of the wafer with the choice of top and bottom edges exclusion matching the lateral distance. The measurements have been carried on utilizing the same lot of wafers. The result is highlighting the need to have sensors positioned exactly at the same distance with respect to the lateral wafers edges and also the need to set the same top and bottom edge exclusion in order to compare TTV measurements from different systems.