Estimating oxide-trap, interface-trap, and border-trap charge densities in metal-oxide-semiconductor transistors

Abstract

A simple method is described that combines conventional threshold-voltage and charge-pumping measurements on n- and p-channel metal-oxide-semiconductor (MOS) transistors to estimate radiation-induced oxide-, interface-, and border-trap charge densities. In some devices, densities of border traps (near-interfacial oxide traps that exchange charge with the underlying Si) approach or exceed the density of interface traps, emphasizing the need to distinguish border-trap contributions to MOS radiation response and long-term reliability from interface-trap contributions. Estimates of border-trap charge densities obtained via this new dual-transistor technique agree well with trap densities inferred from 1/f noise measurements for transistors with varying channel length.