Modeling and Control of Wafer Scale Yield Improvement in Chemical Mechanical Planarization (CMP)

Iowa State University, Ames IA

Investigators

Abstract

The objective of this project is to enhance wafer yield in IC manufacturing by enhancing the wafer scale uniformity in material removal rate during a chemical mechanical planarization process. Reduction and elimination of edge exclusion is of particular interest to this project. An integrated model based control approach will be pursued. An analytical model relating the material removal rate to the wafer - pad interface pressure and wafer backside loading profile will be developed. The model predictions will be verified first under static conditions and from material removal rate data. An active control algorithm based on the above model will be developed. In particular, the curvature control algorithm will be pursued. This will be implemented first in software, and then in hardware. It is anticipated that this project will develop understanding to relate nano-scale nuances of the chemical mechanical planarization process to macro-scale design considerations. This will facilitate efficient optimization and control of process parameters, which is currently done mostly through trial and error iterations. Through Industry-University collaboration, the proposed project will aid in human resource development by exposing graduate and undergraduate students to novel methods of controlling nano-scale material removal processes. Currently a 3-5 mm wafer edge exclusion is used to harvest "usable" chips on wafers, and this affects about 20 percent of the chips on a 300 mm wafer. If successful, this project will directly impact and enhance the yield of such processes.