A New Image Processing Method to Characterize Pad Foam Morphology in Chemical Mechanical Polishing

The polishing pad, typically made of rigid microporous polyurethane foam, plays a primary role in the Chemical mechanical polishing (CMP) process. The pad's mechanical response (such as pad deformation and wear) to polishing and conditioning is is highly related to the foam morphology. This is crucial to the fundamental understanding of the material removal mechanism of CMP. Reported methods of characterizing CMP pad foam morphology are based on intricate and expensive procedures in microtomography, microscopy, spectrometry, etc. This study presents a new image processing method as an alternative for the characterization of the morphological and mechanical properties of CMP pads. Two types of CMP pads (IC1000 and IC1400) are chosen to demonstrate the feasibility of the method. Simulation results prove that the proposed method is effective to determine pad foam characteristics (such as pore shape, size, density as well as dispersion) important to the design of high performance pads.