Wafer clamp detection based on vibration or acoustic analysis

摘要

A workpiece clamping status detection system and method for detecting a clamping state of a clamping device is provided. A clamping device having a clamping surface is configured to selectively clamp a workpiece to the clamping surface. The clamping device may be an electrostatic chuck or a mechanical clamp for selectively securing a semiconductor wafer thereto. A vibration-inducing mechanism is further provided, wherein the vibration-inducing mechanism is configured to selectively vibrate one or more of the clamping device and workpiece. A vibration-sensing mechanism is also provided, wherein the vibration-sensing mechanism is configured to detect the vibration of the one or more of the clamping device and workpiece. Detection of clamping status utilizes changes in acoustic properties, such as a shift of natural resonance frequency or acoustic impedance, to determine clamping condition of the workpiece. A controller is further configured to determine a clamping state associated with the clamping of the workpiece to the clamping surface, wherein the clamping state is associated with the detected vibration of the one or more of the clamping device and workpiece.