Effect of Process Temperature on Coefficient of Friction during CMP

Abstract

This study investigates the effect of heat generation and thermal inputs on the frictional characteristics of interlayer dielectric (ILD) and copper chemical mechanical planarization (CMP) processes. A series of ILD and copper polishes were completed with controlled pad temperatures of 22, 33, and 45°C and various pressures and velocities. Coefficient of friction results indicated an increasing trend for ILD and copper polishing with a rise in polishing temperature. Dynamic mechanical analysis of the used polishing pads revealed links between the softening effects of the pad with rising temperatures and increased shear forces resulting from the contact of the pad and wafer during polishing. The results presented are critical for establishing pad designs with stable dynamic mechanical properties and prolonged pad life. © 2004 The Electrochemical Society. All rights reserved.