Abstract: A one-step CMP process for polishing three or more layer film stacks on a wafer having a multilayer film stack thereon including a silicon nitride (SiNx) layer on its semiconductor surface, and a silicon oxide layer on the SiNx layer, wherein trench access vias extend through the silicon oxide layer and SiNx layer to trenches formed into the semiconductor surface, and wherein a polysilicon layer fills the trench access vias, fills the trenches, and is on the silicon oxide layer. CMP polishes the multilayer film stack with a slurry including slurry particles including at least one of silica and ceria. The CMP provides a removal rate (RR) for the polysilicon layer > a RR for the silicon oxide layer > a RR for the SiNx layer. The CMP process is continued to remove the polysilicon layer, silicon oxide layer and a portion of the SiNx layer to stop on the SiNx layer. Optical endpointing during CMP can provide a predetermined remaining thickness range for the SiNx layer.

Abstract: A one-step CMP process for polishing three or more layer film stacks on a wafer having a multilayer film stack thereon including a silicon nitride (SiNx) layer on its semiconductor surface, and a silicon oxide layer on the SiNx layer, wherein trench access vias extend through the silicon oxide layer and SiNx layer to trenches formed into the semiconductor surface, and wherein a polysilicon layer fills the trench access vias, fills the trenches, and is on the silicon oxide layer. CMP polishes the multilayer film stack with a slurry including slurry particles including at least one of silica and ceria. The CMP provides a removal rate (RR) for the polysilicon layer>a RR for the silicon oxide layer>a RR for the SiNx layer. The CMP process is continued to remove the polysilicon layer, silicon oxide layer and a portion of the SiNx layer to stop on the SiNx layer. Optical endpointing during CMP can provide a predetermined remaining thickness range for the SiNx layer.