Motor-Current-Based Real-Time End Point Detection of Shallow-Trench-Isolation Chemical Mechanical Polishing Process Using High-Selectivity Slurry

Abstract

We have studied the chemical mechanical polishing (CMP) of a shallow-trench-isolation (STI) structure in 0.18 µm semiconductor device fabrication. CMP is applied for the STI structure with and without a reverse moat pattern. The real-time end point detection (EPD) method based on the motor current (MC) signal is tested, and the factors affecting the conventional motor current detection method are investigated. The results showed that the EPD method could not be applied to STI-CMP with a reverse moat etch process due mainly to the pad conditioning effect and the characteristics of an open nitride structure. In the case of direct STI-CMP without a reverse moat etch process, global planarization with low defect levels can be achieved using a high-selectivity slurry (HSS) with a high selectivity for SiO2 and Si3N4, and the EPD method shows acceptable and reproducible results.