A study on detection of wafer process changes using stand-alone wafer metrology tool

With the increasing complexity of semiconductor manufacturing processes and high overlay accuracy requirements, it is increasingly necessary to measure wafer characteristics accurately. When wafer distortion in shape and mark quality changes occur due to wafer characteristic changes, the measurement accuracy in overlay and wafer alignment decreases, resulting in lower yields. Canon has released the stand-alone wafer metrology tool (MS-001) as a solution for high accuracy wafer measurement. It has been reported that high productivity and overlay accuracy can be achieved by measuring the wafer distortion and exposing the wafer aligned based on the measurement results in the exposure system. In this report, the feasibility of detecting the mark quality changes, which is one of the factors of low measurement accuracy, was verified using product wafers. Moreover, it was demonstrated that MS-001 was successful in detecting wafer process variations with high accuracy. These results indicate that MS-001 can solve the issues caused by complex semiconductor manufacturing processes.