Characteristics of silicon nitride after O/sub 2/ plasma surface treatment for pH-ISFET applications

Silicon nitride (Si/sub 3/N/sub 4/) sensing gate pH-ion-selective field effect transistors (ISFETs) were treated by 2.54-GHz microwave O/sub 2/ plasma, the results show the ISFET sensitivity has an advantage up to 24% increment after the plasma treatment. Electron spectroscopy for chemical analysis (ESCA) is used to make sure that the plasma treatment is not just a native oxide cleaning procedure. The samples, which were immobilized with glutaraldehyde used as a bifunctional reagent and 3-aminopropy-Itricthoxysilane used as an adhesion promoter were studied. The binding force between the glucose oxidase and glutaraldehyde immobilized samples, and the element concentrations of nitrogen in 3-aminspropytriethoxysilane immobilized samples are higher which were treated by plasma.