Bulk and Interface Engineering of GeO₂/Ge for High-κ/Germanium Gate Stack

Abstract

Effects of germanium-monoxide desorption on both the interface and the oxide bulk of thermally grown germanium-dioxide as well as its controlling methods have been investigated. The density of interface states was increased and water absorbency of the oxide film was enhanced by the desorption. The density of positive charge strongly depends on amount of water molecules in the oxide. Moreover, the flat-band voltage shift due to the positive charge, which can be generated at a given electric field from donor-like traps, increases linearly with the maximum field in the oxide. It was found that suppression of both the germanium-monoxide desorption and the water absorption are the keys for fabrication of high-quality germanium-dioxide film as an inter-layer of the high-κ/germanium gate stack.

Fabrication of High-k/Ge Stacks with High Quality GeO2 Interlayer

“…To achieve high quality GeO 2 /Ge structure, it is considered that fabrication of GeO 2 at low temperature is necessary from the view point of thermal instability of GeO 2 (3) and capped annealing is effective to improve their characteristics (4). We reported these improvements were due to the atomic re-arrangement of the surface layer of GeO 2 film (5) and the prevention of Ge-O bond breaking by the water molecule close to the GeO 2 /Ge interface (6). During the fabrication of high-N on the GeO 2 /Ge structure using conventional high-N deposition process, however, the GeO 2 interlayer might be redamaged due to water solubility (7) and GeO desorption.…”

Fabrication of High- κ /Ge Stacks with High Quality GeO2 Interlayer

“…One of the candidates of their stacks is high-N/Ge stacks with GeO 2 interlayer, in which the bulk mobilities for both electron and hole are expected to be higher than those of Si. To achieve high quality GeO 2 /Ge structure, capping effects of GeO 2 /Ge are widely known [1] and we reported these improvements were due to i) the atomic re-arrangement of the surface layer of GeO 2 film [2] and ii) the prevention of Ge-O bond breaking by the water molecule close to the GeO 2 /Ge interface [3] . During the fabrication of high-N on the GeO 2 /Ge structure using conventional high-N deposition process, however, the GeO 2 interlayer might be redamaged due to water solubility [3][4] and GeO desorption [5] .…”