The application of a direct STI CMP process in ULSI fabrication

In this paper, development and application of a direct chemical mechanical polishing (CMP) process for shallow trench isolation (STI) on 200mm wafers using high selectivity ceria-based slurry has been studied for production. Post thickness of silicon nitride and trench oxide showed that new direct CMP process has good within-die range and excellent within-wafer uniformity. Improved planarity and less oxide dishing also achieved by cross-sectional SEM photos after direct polish CMP. On the initial process control, trend charts of thickness on silicon nitride and trench oxide after direct STI CMP also have good repeatability and stability. All the data we collected clearly show that the direct STI CMP we developed can be well applied in the mass production of logic devices below 0.18 micron