Yield enhancement through understanding the particle adhesion and removal mechanisms in CMP and post-CMP cleaning processes

Abstract

CMP is considered the primary planarization method in the semiconductor industry. Currently, the polishing physics are not well defined though it is known that the nature of the process makes particle removal after CMP difficult and necessary. It is important to understand the particle adhesion mechanisms resulting from the polishing process and the effect of the adhering force on particle removal in post-CMP cleaning processes. There are few analyses and modeling of CMP polishing process available. Most, of the existing studies recognize the importance of abrasive particles and try to formulate the right model for removal rate. However, the proposed, models all neglect the effects of particle adhesion in their analysis. Current post-CMP techniques are contact cleaning techniques. They are effective, but brush shedding and loading can cause additional contamination. It is important to understand the forces at work at the particle wafer and brush interface as well as understand the combination effect of combining brush and megasonic cleaning in order to maximize removal efficiency and minimize further contamination. Analysis of the particle adhesion and removal mechanisms will be presented for contact and non-contact parameters.