Germanide formation in metal/high-/Ge gate stacks and its impact on electrical properties

Hosoi, Takuji*; Hideshima, Iori*; Minoura, Yuya*; Tanaka, Ryohei*; Yoshigoe, Akitaka ; Teraoka, Yuden; Shimura, Takayoshi*; Watanabe, Heiji*

An understanding of the mechanisms responsible for formation or decomposition of GeO interlayer and Ge diffusion into high- layer is important to develop advanced metal/high- gate stacks for Ge MOSFETs. In this work, we fabricated HfO/GeO/Ge gate stacks by oxidation of thin metal Hf layers on Ge substrates. The effect of plasma oxidation on the change in the bonding states of Ge atoms in HfO/GeO/Ge gate stacks and the structural changes induced by metal electrode deposition and thermal annealing was systematically investigated by synchrotron radiation photoemission spectroscopy (SR-PES) and electrical characterization.