Wettabilily of Polished Silicon Oxide Surfaces

The wettability of silicon dioxide surfaces that have been subjected to chemomechanical polishing has been exam-ined by contact angle measurements and compared to the native thermal oxide. The data from contact angle measure-ments were used to determine critical surface tensions of wetting and work of adhesion values. Contact angle measure-ments indicate that polishing does indeed make the SiO, 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 chem-ical heterogeneity present on the native oxide surface is removed during chemomechanical polishing. Infroduction Single crystal silicon is the most common substrate material used in the electronics industry for integrated circuit manufacturing. Often the silicon surface is oxi-dized by a variety of means to form a relatively thi