chapter  6
34 Pages

Force transmission

The role of the polishing pad consists of two primary processes: (1) the transmission of force to the wafer surface and (2) the distribution of slurry to the wafer surface. This chapter will examine the role the pad plays in generating a force field across the wafer surface during the planarization process. Although many elements come into play during this process, and different polishing circumstances affect these elements differently, the nature of these parameters and their interaction will be examined in a general fashion. This chapter will review the following topics: the inherent nature of a typical pad polymer and its response to force impulses, the nature of cellular solids and the roles typical pad pores can play, the characteristics of asperities and their role in force transmission, and finally some considerations about abrasives and their likely participation in material removal.