Impact of Technology Scaling on ISFET Performance for Genetic Sequencing

This paper investigates the impact of technology scaling according to Moore´s law on the performance of ion-sensitive field-effect transistors (ISFETs) as pH sensors for genetic sequencing. Two commercial CMOS process families, including 0.35, 0.18, 0.13, and 0.09 μm m processing nodes, have been used to model ISFETs of different sizes and biasing conditions with simulation results indicating that the noise behavior of a ISFET deviates significantly from the underlying MOSFETs. In particular, a capacitive division effect is observed at the gate due to the passivation and parasitic capacitances, effectively attenuating any signal and noise. The dependence of the attenuation on gate parasitics means that smaller devices, which operate in the weak inversion region, cause the least attenuation, therefore, lowest input referred noise, a result that is contradictory to what is expected with MOSFETs.