Abstract: The polishing of a layer of boro-phosphate-silicate-glass (BPSG) is not easy to control as a result of CMP slurry chemistry effects, the doping concentration of the layer of BPSG and the heat treatment to which the layer of BPSG has been submitted prior to the process of CMP. The invention has developed a CMP endpoint detection mode that minimizes variations of the process of CMP of a layer of BPSG by these factors. An endpoint detection algorithm has been developed, which has been applied and has proven to significantly improve a statistical measure, which reflects the process deviation from the process mean for the process of CMP of a layer of BPSG.