Category of Work
Article
Publication Title
Electronic Materials
Abstract
We investigated the tribological, thermal, kinetic, and surface microtextural characteristics of chemical mechanical polishing (CMP) of 300 mm p-type <100> prime silicon wafers (and their native oxide) at various pressures, sliding velocities, and starting platen temperatures. Results showed the dominant tribological mechanism for both native oxide and silicon polishing to be boundary lubrication. Using frictional data, we pinpointed the exact time that corresponded to the total removal of the native oxide and the onset of silicon polishing. This allowed us to separately characterize removal rates of each layer. For native oxide, while the rate depended on temperature, the presence of a temperatureindependent shear force threshold and the low observed rates suggested that its removal by the slurry was dominantly mechanical. In contrast, for silicon polish, the absence of a distinctive shear force threshold and the fact that, for the same set of consumables, rates were more than 200 times larger for silicon than for native oxide suggested a dominantly chemical process with an average apparent activation energy of 0.34 eV. It was further confirmed that rate selectivity between native oxide and PE-TEOS based SiO2 control wafers was around 1 to 7, which underscored the importance of being able to directly measure native oxide removal rates. In all cases, we achieved excellent post-polish surfaces with Sa and Sq values of below 1 nm. Due to thermal softening of the thermoplastic pad at elevated temperatures, which we confirmed via dynamic mechanical analysis, overall process vibrations were significantly higher when platen heating was employed.
DOI
https://doi.org/10.3390/electronicmat6010001
Publication Date
1-8-2025
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Yap, Michelle; Yap, Catherine; Sampurno, Yasa; Whitener, Glenn; Keleher, Jason; Borucki, Len; and Philipossian, Ara, "Tribological, Thermal, Kinetic, and Surface Microtextural Characterization of Prime p-Type <100> Silicon Wafer CMP for Direct Wafer Bonding Applications" (2025). Chemistry Department Faculty Articles. 13.
https://digitalcommons.lewisu.edu/chemistry_facpubs/13
