Patent ID: 7153182

Claim:
An apparatus for in situ measurement of polishing pad smoothness comprising: a belt movably mounted on at least one roller, wherein a roller motor rotatably drives the at least one roller; a platen disposed underneath the belt, the platen configured to dispense a fluid bearing between the platen and the belt, the belt comprising a polishing pad positioned on a side of the belt facing away from the platen; a flow meter in communication with a fluid supply line connected with the platen, the flow meter monitoring a flow rate of fluid to the platen; a sensor in communication with the fluid bearing to measure a pressure change of the fluid while a material is polished; and a controller in communication with at least one of the sensor, the flow meter or the roller motor, the controller operative to monitor a pad smoothness during a wafer polishing process based on receipt of pad smoothness information at the controller, the pad smoothness information comprising at least one of a roller motor current sensed at the roller motor, a fluid flow rate sensed at the flow meter or a pressure sensed at the fluid bearing.