A signal processing method for the friction-based endpoint detection system of a chemical mechanical polishing(CMP) process is presented.The signal process method uses the wavelet threshold denoising method to reduce the noise contained in the measured original signal,extracts the Kalman filter innovation from the denoised signal as the feature signal,and judges the CMP endpoint based on the feature of the Kalman filter innovation sequence during the CMP process.Applying the signal processing method,the endpoint detection experiments of the Cu CMP process were carried out.The results show that the signal processing method can judge the endpoint of the Cu CMP process. A signal processing method for the friction-based endpoint detection system of a chemical mechanical polishing (CMP) process is presented. The signal processing method uses the wavelet threshold denoising method to reduce the noise contained in the measured original signal, extracts the Kalman filter innovation from the denoised signal as the feature signal, and judges the CMP endpoint based on the feature of the Kalman filter innovation sequence during the CMP process. Applying the signal processing method, the endpoint detection experiments of the Cu CMP process carried out. show that the signal processing method can judge the endpoint of the Cu CMP process.