Effect of pad surface micro-texture on dishing and erosion during shallow trench isolation chemical mechanical planarization

Abstract

The effect of pad surface micro-texture on dishing and erosion during shallow trench isolation (STI) chemical mechanical planarization was investigated. To generate different pad surface micro-textures, a 3M A2810 disc (3M) and a Mitsubishi Materials Corporation disc (MMC) were used to condition a Dow® IC1000™ K-groove pad. For each disc, 200-mm blanket TEOS wafers and SKW3-2 STI wafers were polished. Results showed that the two discs generated similar blanket wafer removal rates, while the MMC disc generated significantly higher dishing and erosion compared to the 3M disc during patterned wafer polishing. Pad surface topography was analyzed using laser confocal microscopy after patterned wafer polishing. Results showed that the MMC disc generated a pad surface with significantly higher mean pad summit curvatures than the 3M disc. As the MMC disc generated more and sharper pad asperities, it resulted in higher dishing and erosion as these sharp asperities make greater direct contact with the “down” features.