Analytical solution for RESURF and breakdown characteristics of finger STI DEMOS transistors

Finger STI DEMOS transistors are fabricated and its electrical characteristics is studied. The conformal mapping method, which relates the reduction of the doping concentration to the width (z
o
) of the drain extension (DE) finger and the gap (z
d
) between the poly plate and the DE finger is used to estimate the reduction of the doping concentration theoretically. Based on this reduced doping concentration, a breakdown voltage (BV) model is derived. The predictions of this model agree very well with the experimental data.