Re-examination of pressure and speed dependences of removal rate during chemical-mechanical polishing processes

A new removal rate model which is a modification to the Preston equation is developed to re-account the dependence of removal rate on the down force (pressure) and rotation speed during the chemical-mechanical polishing (CMP) process. The removal rate is first expressed as a linear function of both normal and shear stresses. The analogy of the CMP removal process to traveling indenters is considered and the stresses acting upon the abrasive particles (indenters) are formulated using previous models based on principles of elasticity and fluid mechanics. An expression is then derived which predicts the (pressure)(56) and (speed)(1/2) dependences of the removal rate. Experimental results with thermal oxides are consistent with the predictions.