Indium diffusion through high-k dielectrics in high-k/InP stacks

Abstract

Evidence of indium diffusion through high-k dielectric (Al2O3 and HfO2) films grown on InP (100) by atomic layer deposition is observed by angle resolved X-ray photoelectron spectroscopy and low energy ion scattering spectroscopy. The analysis establishes that In-out diffusion occurs and results in the formation of a POx rich interface.

In situ study of e-beam Al and Hf metal deposition on native oxide InP (100)

“…This suggests indium diffusion through the Al/Al-oxide overlayer. 12 For the P 2s spectra, the bulk peak at 186.8 eV is assigned to InP, and the peak with a binding energy separation of þ6 eV from the InP bulk peak is assigned to P 2 O 5 , which is consistent with the deconvolution of the P 2p spectra. In contrast to the In-In bond, both before and after annealing, the decrease in intensity for both the In-P and the P-oxide peaks is consistent with equal attenuation by the Al/Al-oxide overlayer, suggesting that no P-oxide diffusion is detected by ARXPS.…”

“…9,10 The "clean up" effect, whereby the oxygen is seen to transfer from the native oxides to form Al 2 O 3 and HfO 2 , is observed for the In-oxides after the first pulse of metal precursors, but the "clean up" effect does not occur for the P-oxides, leaving a P-rich oxide. 9 Recently, indium out-diffusion through high-k dielectrics upon annealing has been reported, 11,12 resulting in a P-rich interface, which have been correlated to the interface trap density (D it ) from electrical analysis. 13,14 It is, therefore, critical to control this P-rich oxide concentration at the interface for InP/high-k stack.…”

Indium penetration through thermally grown silicon oxide

“…Temperatures higher than 800 C were required to optimize dopant activation in InGaAs [8]. Outdiffusion of indium through oxide insulator layers becomes an issue [9]. Anomalous indium diffusion in silicon oxides was reported [10].…”

In situstudy of atomic layer deposition Al2O3on GaP (100)

“…The strong tendency of In-diffusion is reflected from recent studies of In diffusion through high-k dielectrics in (HfO 2 and Al 2 O 3 )/InP stacks. 22,23 For the acid etched and the S-passivated samples, prior to ALD, relatively low concentrations of Ga 2 O and GaPO 4 ÁxH 2 O states are detected compared with the native oxide sample. After annealing in the ALD reactor, an increase in the concentration of Ga-oxides is observed.…”