Embedded spectroscopic reflectometry metrology on FEOL silicon dioxide trench polishing equipment: ER: Equipement reliability and productivity enhancements

Abstract

The challenge in the research is to develop a material thickness measurement method to monitor oxide polishing by Chemical-Mechanical Planarization (CMP) in the Shallow Trench Isolation (STI). The underlying aim is to build a statistical regulation model for the polishing time on one platen (the two others platens are monitored by an endpoint signal). In addition to the process parameters (head sweep, platen, and head rotation velocity), input and output polished material thicknesses data are essential to build a run-to-run model for CMP. Therefore, stack layer thickness, before and after polishing, needs to be measured fast enough to maintain the acceptable throughput and to control truthfully the polishing time wafer by wafer. In this paper, we describe how the spectroscopic reflectometry embedded in the polishing equipment, can meet the requirements of rapidity and capability of setting up a run-to-run control algorithm to maintain the thickness target for CMP STI.