Study On Interferometer Measurement Error Model In Wafer Stage

Precision moving stage with multi-DOF, high speed and high accuracy is one of key components of IC equipment and precision machining tool. Its accuracy impacts directly on machine performance. So it is important to do research on stage motion control. Accurate measurement model is foundation of high-precision motion control. There are a lot of parameters which are needed to calibrate and identify in the model. And wafer stage motion performance is influenced by the results of parameter identification and calibration. The thesis focuses on 6-axis interferometer measurement error in wafer stage. Quantitative analysis of the measurement errors is done. Models for abbe error and cosing error are also established.These models calculate each optical path of four light beams between interferometer and wafer stage at different measurement zone. So 6 optical paths of X and Y directions can be calculated with weight factors. Based on 6 optical paths of X and Y directions at titled stage and rotated stage, 6 optical paths of X and Y directions at tilted light beam with tilted stage and rotated interferometer light beam with rotated stage can be written. So the measurement error model including machine constants can be established with mathematical conversion and Superposition.Machine constants of the error model are calculated according to the experimental data. So the error model can be verified by the experiment. This model is confirmed to have good application in lithography prototype. Position error of Y axis can be improved from 100 nm to 10 nm with this model. It obviously improves the positioning precision of the wafer stage. This model can be used in others multi-DOFs stage.