Characteristics of silicon nitride after O2 plasma surface treatment for pH-ISFET applications.

Silicon nitride (Si3N4) sensing gate pH-ion-selective field effect transistors (ISFETs) were treated by 2.54-GHz microwave O2 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-aminopropyItriethoxysilane 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-aminopropyltriethoxysilane immobilized samples are higher which were treated by plasma.