Hydrogen Sensitivity of InP HEMTs With WSiN-Based Gate Stack

Abstract

Abstract-We have experimentally investigated the hydrogen sensitivity of InP high-electron mobility transistors (HEMTs) with a WSiN-Ti-Pt-Au gate stack. We have found that exposure to hydrogen produces a shift in the threshold voltage of these devices that is one order of magnitude smaller than published data on conventional Ti-Pt-Au gate HEMTs. We have studied this markedly improved reliability through a set of quasi-two-dimensional mechanical and electrostatic simulations. These showed that there are two main causes for the improvement of the hydrogen sensitivity. First, the separation of the Ti-layer from the semiconductor by a thick WSiN layer significantly reduces the stress in the heterostructure underneath the gate. Additionally, the relatively thinner heterostructure used in this study and the presence of an InP etch-stop layer with a small piezoelectric constant underneath the gate reduces the amount of threshold voltage shift that is caused by the mechanical stress.Index Terms-High-electron mobility transistors (HEMTs), hydrogen, InP, piezoelectric effect, reliability.

Hydrogen sensitivity of InP HEMTs with WSiN-based gate stack

“…8 shows as a function of , as predicted by this model. The model also indicates that at the gate-semiconductor interface, , scales inversely proportional with (5) This result is consistent with the evolution of with observed experimentally and through 2-D simulations in TiPtAu conventional gates in which it is seen that increases in magnitude as the gate length shortens [6].…”

“…The goal of this paper is to study the H sensitivity of InP HEMTs with a WSiN-Ti-Pt-Au gate stack [1] and to compare it to that of more conventional Ti-Pt-Au gate stack designs. The work presented in this paper is an updated and expanded version of preliminary results in [5].…”