Electrical properties of germanium/metal-oxide gate stacks with atomic layer deposition grown hafnium-dioxide and plasma-synthesized interface layers

Abstract

The electrical properties of metal-oxide-semiconductor (MOS) capacitors composed of atomic-layer-deposited (ALD) hafnium-dioxide (HfO2) dielectrics and plasma-synthesized interface layers were investigated. MOS capacitor with oxynitride interface layer shows negative flatband voltage (Vfb) shift from the ideal value. Hafnium-alkylamide ALD process performed on a plasma nitrided silicon surface causes negative Vfb shift. Germanium MOS capacitors show additional negative Vfb shift (−0.5V). X-ray photoelectron spectroscopy shows evidence of germanium diffusion into the HfO2 layer. Germanium MOS capacitor with tantalum-oxynitride (TaON) interface layer shows superior electrical properties. These results indicate that the selection of the interface layer strongly influences germanium MOS capacitor electrical properties.

On the dc and noise properties of the gate current in epitaxial Ge p-channel metal oxide semiconductor field effect transistors with TiN∕TaN∕HfO2∕SiO2 gate stack

“…6,7 In spite of this progress, questions remain about the quality of the high-k metal gate stack on Ge due to the large amount of Ge that can be found inside the HfO 2 when HfO 2 is deposited on Ge. 3, 8,9 Hf based as well as diffused Ge related defects can cause serious reliability issues such as threshold voltage instability, bias temperature instability, and trap assisted tunneling. 10 In this letter, we investigate the quality of a TiN / TaN / HfO 2 / SiO 2 gate stack on epi-Ge pMOSFETs through measurements of the dc and the noise characteristics of the gate current.…”

“…12 A possible explanation is that the traps responsible for enhanced PF conduction in the device operative regimes are due to Ge out diffusion into the gate oxide. 3,7,8,13 On wafer gate current, low frequency noise measurements have been done by using a dedicated noise measurement system. 9 The gate current power spectral density ͑PSD͒ for both Ge pMOSFETs and reference Si pMOSFETs show a 1/ f ␥ behavior with ␥ nearly equal to 1.…”

Defect configurations of high-k cations in germanium

“…[43][44][45] In Ge/oxide interfaces (for example, Ge/high-k oxide or Ge/GeO x /high-k oxide), there have also been numerous reports that during volatilization germanium out-diffuses into the oxide in the form of Ge atoms or as GeO molecules. 30,[46][47][48][49][50] This could form lattice vacancies or divacancies (V 2 ) in Ge among other possible defects. It is also anticipated that cations from the oxides will diffuse into Ge.…”

Improved electrical properties of Ge metal-oxide-semiconductor capacitor with HfTa-based gate dielectric by using TaOxNy interlayer

“…This is because tantalum nitride can function as a diffusion barrier and can be oxidized to form nonconductive TaO x N y after annealing in O 2 . Moreover, Sugawara et al 8 demonstrated that a thin plasma-synthesized TaON interlayer on Ge could reduce stress-induced flatband-voltage shift.…”