Title :
Effects of Sulfur Passivation on Germanium MOS Capacitors With HfON Gate Dielectric
Author :
Xie, Ruilong ; Zhu, Chunxiang
Author_Institution :
Nat. Univ. of Singapore, Singapore
Abstract :
In this letter, we study the effects of sulfur (S) passivation, using aqueous ammonium sulfide ((NH4)2S), on germanium (Ge) MOS capacitors with sputtered HfON as gate dielectric and TaN as metal-gate electrode. Compared with control samples, the S passivation can effectively reduce both equivalent oxide thickness and interface-state density. X-ray-photoelectron-spectroscopy analysis shows that (NH4)2S treatment can reduce the Ge-O bonds on Ge surface. The thermal stability of the S passivation under different postmetal-annealing temperatures was also examined, and it was found that samples with (NH4)2S treatment exhibit stable Ge/high-fc interface upon 550-deg C postmetal-deposition annealing, whereas interface quality degrades for those samples without S passivation.
Keywords :
MOS capacitors; X-ray photoelectron spectra; ammonium compounds; annealing; dielectric materials; elemental semiconductors; germanium; hafnium compounds; passivation; sulphur; tantalum compounds; thermal stability; (NH4)2S; Ge; Ge MOS capacitors; HfON; HfON gate dielectric; TaN metal-gate electrode; X-ray-photoelectron-spectroscopy; aqueous ammonium sulfide; equivalent oxide thickness; germanium MOS capacitors; interface-state density; postmetal-deposition annealing; sulfur passivation effects; thermal stability; Annealing; Dielectrics; Electrodes; Germanium; MOS capacitors; Passivation; Surface treatment; Temperature; Thermal stability; Thickness control; Germanium (Ge); MOS capacitor; sulfur (S) passivation;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2007.907415
