The surface site dehydration mechanism for Si/sub 3/N/sub 4/ sensing membrane by post-baking treatment

This work presented a post-baking treatment effect on Si/sub 3/N/sub 4/ sensing membrane for the pH response. Special measurement sequences were proposed to verify the surface site activation and de-hydration. Sensitivity was improved by pH4 buffer solution immersion. However, sensitivities were decreased 3-8.5 mV/pH and 1-2.8mV/pH by first and second baking cycle respectively. Higher baking temperature made the sensitivity decrease more. It was due to ion and surface site exchange and repaired the dangling bond on sensing membrane during buffer immersion. The post-baking treatment broke some active sites by thermal energy. The higher baking temperature provided more thermal energy to break active sites and degrade more sensitivity. A novel physical model was proposed for the activation and dehydration behavior.