RTPC X Pre-Thickness Control Function on Metal Chemical Mechanical Polishing (CMP) Process

Previous thickness value is an essential parameter to qualify the wafer status in semiconductor manufacturing industry. It will significantly influence the CMP process results if the thickness is out of spec. Based on currently CMP tool, the dielectric layer thickness can be measured by optical spectrum, while metal thickness has no method to define. Here, this paper introduces a novel approach to achieve the previous thickness control function by detecting the eddy current variation for metal layer. This method greatly reduces the risk of irreversible polishing wrong product by controlling the wafer in-coming thickness for each piece of metal layer wafer.