Wettability of Polished Silicon Oxide Surfaces

The wettability of silicon dioxide surfaces that have been subjected to chemomechanical polishing has been examined by contact angle measurements and compared to the native thermal oxide. The data from contact angle measurements were used to determine critical surface tensions of wetting and work of adhesion values. Contact angle measurements indicate that polishing does indeed make the surfaces more wettable through the formation of silanols. This is demonstrated by comparison of work of adhesion values. Upon heating, there is a steady decrease in work of adhesion values for the native and polished oxide surface. Dehydration (evaporation and condensation of silanol groups) can be observed through the work of adhesion values as the samples are heated from ambient to 280°C. The loss of water occurs gradually to give a surface which is relatively hydrophobic to water. Contact angle hysteresis data indicate that the chemical heterogeneity present on the native oxide surface is removed during chemomechanical polishing.