Titanium hydride formation in Ti/Pt/Au-gated InP HEMTs |
| |
Authors: | Blanchard RR Comet A del Alamo JA |
| |
Affiliation: | MIT, Cambridge, MA; |
| |
Abstract: | Ti/Pt metal layers are an integral part of the gate stack of many GaAs PHEMTs and InP HEMTs. These devices are known to be affected by H 2 exposure. In this study, Auger Electron Spectroscopy (AES) measurements of Ti/Pt bilayers are correlated with electrical measurements of InP HEMTs fabricated with Ti/Pt/Au gates. The FET measurements show that H2 exposure shifts the device threshold voltage through the piezoelectric effect. AES reveals the formation of titanium hydride (TiHx) in Ti/Pt bilayers after identical H2 exposures. These results indicate that the volume expansion associated with TiHx formation causes compressive stress in Ti/Pt/Au gates, leading to the piezoelectric effect. After a subsequent recovery anneal in N2, the FET measurements show that VT recovers. AES measurements confirm that the TiHx in hydrogenated Ti/Pt bilayers also decreases after further annealing in N2 |
| |
Keywords: | |
|
|