Dummy design characterization for STI CMP with fixed abrasive

Abstract

The Shallow Trench Isolation (STI) Chemical Mechanical Polishing (CMP) process has an essential role in the STI module for the fabrication of the Complementary Metal Oxide Semiconductor (CMOS) transistors. Since the 0.13 μηι technology node a direct STI CMP approach is used, where an oxide film is polished to remove the topography after trench fill and to clear the active regions stopping on a silicon nitride layer. One of the approaches for direct STI CMP uses a Fixed Abrasive (FA) web, which provides excellent planarity. Dummy structures are implemented in the device manufacturing layouts in order to overcome the effect of the different patterned densities and feature sizes. The design of the dummy structures plays a critical role for the CMP performance. In this work, a detailed characterization of the impact of the dummy design on the STI CMP performance using FA has been performed. Based on it, CMP optimized dummy designs have been found. The optimum dummy designs are vertical lines with higher patterned density (PD ∼> 30 %) and smaller spacing in у ( 23 %) and smaller width and spacing of the lines.