Method for non-contact stress evaluation of wafer gate dielectric reliability

摘要

An apparatus and method for evaluating the performance of a test dielectric material for use as a gate dielectric. The method comprises exposing a coated layer of the dielectric to a concentration of atomic hydrogen. The method may comprise (a) measuring an initial value of interface-state density in the test dielectric, (b) exposing the coated test dielectric to a concentration of atomic hydrogen in a remote plasma, and then (c) measuring a post-exposure value of interface-state density in the test dielectric. Steps (b) and (c) may be repeated with incrementally higher concentrations of atomic hydrogen to determine a rate of change in interface-state density value as a function of atomic hydrogen concentration, which may then be related to the projected charge-to-breakdown or time-to-breakdown of the test dielectric layer when the dielectric is used as the gate dielectric. The method may be conducted on a remote-plasma hydrogen exposure apparatus comprising, in series, a source of a mixture of molecular and atomic hydrogen gas; a particle remover adapted to remove energetic, charged particles; a light sink; a hydrogen recombination device; and a wafer exposure chamber.