Investigations in polysilicon CMP to apply in sub-quarter micron DRAM device

The chemical mechanical polishing (CMP) of polysilicon is an important technique to form polysilicon plugs or damascene lines in a sub-quarter micron DRAM device. The removal of polysilicon by CMP can reduced the recess in polysilicon plugs compared with conventional reactive ion etch (RIE). Furthermore, the damascene line scheme of polysilicon prevents serious voids formation and significant amounts of recess in inter layer dielectric (ILD) before formation of the contact. We discuss the characteristics of polysilicon CMP and the post cleaning process. In this paper, we also compared the performance of the polysilicon plug with that of the polysilicon damascene line by CMP.