Effect of randomness in the distribution of impurity ions on FET thresholds in integrated electronics

A model of the effect of random fluctuations in the number of impurity atoms in the depletion layer of a field-effect transistor (FET) is presented and analyzed. It is conducted that the range of space charge per unit area that must be anticipated on a chip containing N FET's each of area A is /spl Delta/S=q(2 ln N)/SUP 1/2/A/SUP -1/4/n~/SUP 1/2/. n~ is the doping level of the substrate.