CMP Process and Consumables Evaluation with PadProbe~R

摘要

The PadProbe~R with simultaneous real-time measurements of PadFriction and PadWear was used to evaluate a copper CMP process and consumables. During conditioning, PadFriction reaches its optimum level. Any further continued conditioning has to be eliminated, as it wears the pad without any improvement to its surface. The moment when PadFriction is stabilized at its optimum level defines the end-point of conditioning. Monitoring PadWear allows for determination of pad life and can trigger an alarm signal when the critical wear level is reached, for example, based on the depth of pad grooves. When PadFriction drops out of the process window, there are two common causes: if PadWear is close to its critical level the pad has to be replaced, if PadWear is still low the conditioner has to be replaced. The observed correlation of the in-situ measured PadFriction with post-polish measured Removal Rate and Non-Uniformity of Polishing confirms the PadProbe~R usefulness for in-situ process control. Several types of conditioners were tested on two types of pads. The simultaneous measurements of PadWear and PadFriction allowed us to effectively choose the optimum conditioner-pad combination.