Rapid electrical measurements of back oxide and silicon film thickness in an SOI CMOS process

Abstract

A method which uses the front and the back gates of a fully depleted SOI transistor to extract the thickness of both the silicon film and the buried oxide is described. This is done by plotting the variation of the threshold voltage of the transistor driven by one gate versus the bias on the other gate and vice versa. Both the silicon film and the buried-oxide thicknesses can be derived independently. Any SOI transistor that can go into a fully depleted mode can be used. >