Experimental and numerical analysis of wafer-to-wafer uniformity in double-sided polishing

Double-sided polishing (DSP) is a key process used to achieve super-flatness for 300-mm silicon wafers. Precisely controlling the uniformity of wafer thickness and flatness by DSP is important in advanced node-integrated circuit manufacturing. In this work, the dependence of variations in wafer-to-wafer thickness on wafer original thickness and carrier thickness was investigated. This research indicates that the thickness difference between the wafer and the carrier affects the deformation of the pad and thus changes the removal rate of material in the DSP process, which finally induces the non-uniformity. Besides, the platen shift caused by inconsistent original wafer thickness or carrier thickness is another key factor affecting wafer-to-wafer thickness uniformity. This work may provide guidance for producing high flatness uniformity wafers by optimizing the DSP process.