Design optimization of diamond disk pad conditioners

Abstract

Chemical mechanical planarization (CMP) is the major manufacturing step used to planarize semiconductor wafers and obtain mirror surface finish. In CMP, diamond disk pad conditioning is traditionally employed to restore pad planarity and surface roughness. The conditioning tool typically consists of a metal disk with one side embedded with protruding diamond grits (abrasives). The conditioner design has a significant effect on the pad conditioning process and hence the wafer planarization process. This paper proposes the application of engineering optimization methods such genetic algorithm to the conditioner design problem for the first time. A new metric to evaluate conditioning performance based on the conditioning density generated by a specific conditioner design is developed. The metric is applied in a genetic algorithm to optimize conditioner design parameters (including geometric arrangement of diamonds, grit density and disk size). The model searches for the design parameters that produce a desired CMP pad surface texture. Results show that the model can effectively serve as a platform to evaluate and tune conditioner design for different applications in CMP.