Interferometric measurement of thickness variation of double-sided polished wafer

Xiaoyue Bian; Sen Han; Jun Cheng; Linghua Zhang; Quanzhao Wang; Xueyuan Li; Quanying Wu

doi:10.1117/12.2643049

19 December 2022 Interferometric measurement of thickness variation of double-sided polished wafer

Xiaoyue Bian, Sen Han, Jun Cheng, Linghua Zhang, Quanzhao Wang, Xueyuan Li, Quanying Wu

Proceedings Volume 12319, Optical Metrology and Inspection for Industrial Applications IX; 123191B (2022) https://doi.org/10.1117/12.2643049
Event: SPIE/COS Photonics Asia, 2022, Online Only

Conference Poster

Abstract

Wafer, the primary material used to make semiconductor chips, are found in almost every type of electronic device used in everyday life. As the quality of wafer used in large-scale integrated circuits has improved considerably, the diameter of wafer has continued to increase, and the thickness of silicon wafer has become increasingly thin. Wafer manufacturers and device manufacturers are increasingly focusing on wafer thickness variation. In the past few years, the usual capacitive tools for wafer inspection have been replaced by interferometric tools for higher sensitivity and resolution. We, therefore, describe a method that uses two Fizeau-type phase-shift interferometers to simultaneously measure the front and back surfaces of a vertically placed wafer and calculate the thickness variation of the wafer based on the resulting morphologies. The reliability of the method was verified by comparing the wafer thickness variation obtained from experimental measurements with that obtained from optical glass bonding. Over three days, five consecutive measurements were performed daily on 50mm wafer using this method, and the experimental results showed that the average values of RMS (Root Mean Square) of the thickness variation calculated for each day were 41.843nm, 40.751nm, and 40.490nm, and the average values of PV (Peak to Veally) were and 206.761nm, 205.252nm, and 209.800nm, and the measurements proved to be highly reproducible. The method has good stability and reliability to meet the measurement of wafer thickness variation.

Citation Download Citation

Xiaoyue Bian, Sen Han, Jun Cheng, Linghua Zhang, Quanzhao Wang, Xueyuan Li, and Quanying Wu "Interferometric measurement of thickness variation of double-sided polished wafer", Proc. SPIE 12319, Optical Metrology and Inspection for Industrial Applications IX, 123191B (19 December 2022); https://doi.org/10.1117/12.2643049

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