Transconductance Degradation in Thin-Oxide MOSFET's

Abstract

In this work we investigate the transconductance degradation effect which occurs in thin-oxide FET's due to the finite inversion-layer capacitance and to the decrease of the electron mobility as the electric field increases. Experimental capacitance and charge measurements are performed at room and at liquid-nitrogen temperature on 10-nm oxide FET's, and the data are compared with a classical and a quantum-mechanical model extended to take into account the nonuniform doping profile in the silicon substrate. Accurate mobility determinations are performed accounting for the nonuniform distribution of the mobile charge along the channel, and a mobility expression against the average normal field is incorporated in a generalized Pao-Sah double-integral formula for the FET drain current. Design tradeoffs for submicrometer FET's are finally discussed. Copyright © 1983 by The Institute of Electrical and Electronics Engineers, Inc.