Wafer Edge Peeling Defect Mechanism Analysis and Reduction in IMD Process

An innovative model of the mechanism for peeling defect in inter metal dielectric(IMD) process induced by poor adhesion between metal and oxide film on wafer bevel is presented. Peeling defect is inspected by dark field inspection (DFI) tool of KLA. Scanning electron microscopy (SEM) and Transmission electron microscope (TEM) are used to study the stack and composition of wafer edge film. Peeling defect source will be discussed in this paper, and the tests demonstrated metal film and oxide film's growth ability varied at wafer bevel, that induce metal film accumulate approach to wafer bottom bevel, when the thick oxide film of next layer deposition, they cannot bond firming, the films peel off with the mechanical transfer or high temperature. Solution of to avoid peeling defects with bevel clean also was demonstrated as well.