US Patent 7163435 Real time monitoring of CMP pad conditioning process

CMP pad conditioning processes have been monitored and controlled by detecting the vibrational spectrum of a sensor mounted on the conditioner support arm. An accelerometer is used as the detector so that vibrational velocity (which correlates with pad wear) can be measured, rather than displacement or acceleration. After the vibrational spectrum has been transformed to its frequency domain equivalent, it is monitored for the presence of abnormal peaks in order to control the conditioning process.