Amplitude monitoring system, focusing and leveling device, and defocusing amount detection method

Abstract

Disclosed are an amplitude monitoring system, a focusing and leveling apparatus and a defocus detection method. The defocus detection method comprises the steps of: adjusting amplitude of a scanning mirror (201) to a theoretical amplitude value and recording corresponding theoretical output voltage values of a photodetector (309) (S1); adjusting the amplitude of the scanning mirror (201) and sampling real-time amplitude values θi of the scanning mirror (201) and real-time output voltage values of the photodetector (309) to calculate compensated real-time demodulation results Si, and recording real-time defocus amounts Hi of a wafer table (305) (S2); subsequent to stepwise displacement of the wafer table (305), establishing a database based on the compensated real-time demodulation results Si and the real-time defocus amounts Hi of the wafer table (305) (S3); and in an actual measurement, sampling in real time an actual amplitude value θk of the scanning mirror (201) and actual output voltage values of the photodetector (309) to calculate a compensated real-time demodulation result Sk, and finding an actual defocus amount Hk of the wafer table (305) by searching the database using a linear interpolation method (S4). Such a focusing and leveling apparatus and defocus detection method avoid degraded stability of the scanning mirror due to long-time operation, which may lead to low wafer surface defocus measurement accuracy of the focusing and leveling apparatus.

Dependencies are inferred from the claim text.