Title :
A physical model for threshold voltage instability in Si3N4-gate H+-sensitive FET´s (pH ISFET´s)
Author :
Jamasb, Shahriar ; Collins, Scott D. ; Smith, Rosemary L.
Author_Institution :
IBM Corp., Endicott, NY, USA
fDate :
6/1/1998 12:00:00 AM
Abstract :
A physical model is presented which quantitatively describes the threshold voltage instability, commonly known as drift, in n-channel Si 3N4-gate pH ISFET´s. The origin of the so-called drift is postulated to be associated with the relatively slow conversion of the silicon nitride surface to a hydrated SiO2 or oxynitride layer. The rate of hydration is modeled by a hopping and/or trap-limited transport mechanism known as dispersive transport. Hydration leads to a decrease in the overall insulator capacitance with time, which gives rise to a monotonic temporal increase in the threshold voltage
Keywords :
capacitance; hopping conduction; insulating thin films; ion sensitive field effect transistors; pH measurement; semiconductor device models; silicon compounds; solvation; stability; H+-sensitive FET; Si3N4; Si3N4-gate pH ISFET; SiO2; dispersive transport; drift; hopping transport mechanism; hydrated SiO2; hydration rate; insulator capacitance reduction; n-channel ion sensitive FET; oxynitride layer; physical model; threshold voltage instability; trap-limited transport mechanism; Capacitance; Dielectrics and electrical insulation; Dispersion; Electrons; FETs; Packaging; Polarization; Sensor phenomena and characterization; Silicon; Threshold voltage;
Journal_Title :
Electron Devices, IEEE Transactions on
