Publications Details
Particle-surface interactions in chemical mechanical polishing
Material removal in chemical mechanical polishing (CMP) occurs by a pressure accentuated chemical attack of the surface. The polishing slurry typically consists of abrasive particles and reactive chemicals that may or may not include an oxidant. Post-CMP cleaning processes must remove both the ionic contaminants and any remaining polishing slurry particles. Central to the effectiveness of a clean is the use of conditions that will minimize the binding force between the residual particles and the wafer surface. The morphology and composition of the particle, the surface from which it must be removed, and the environment surrounding the wafer will determine the magnitude of forces that hold a particle to the wafer surface. At the Sandia/SEMATECH Center for Contamination Free Manufacturing, two techniques--atomic force microscopy (AFM) and electrokinetic deposition--are being used to explore these interactions for CMP of both oxide and tungsten surfaces. A basic understanding of particle-surface interaction forces and how they are affected by the chemical/physical environment of the particle and surface is the objective of this task. Modification of the binding forces between particles and wafer surfaces may be used to maximize post-CMP cleaning effectiveness.