Deposition of Hf–silicate gate dielectric on SixGe1−x(100): Detection of interfacial layer growth

Abstract

The deposition of a stable high-κ dielectric material such as hafnium silicate in direct contact with strained epitaxial SixGe1−x(100) layers on Si(100) provides the prospect of eliminating the Si buffer layer that is currently used to form the gate oxide in SiGe-based devices. In this study, ∼3-nm-thick hafnium silicate films were produced by sputter deposition of hafnium silicide films on precleaned SixGe1−x(100), with subsequent UV-O3 oxidation at room temperature. Prolonged UV-O3 exposure at room temperature leads to the growth of an interfacial layer comprised of a mixture of silicon and germanium oxides. We report on the use of x-ray photoelectron spectroscopy, particularly the x-ray excited Ge (L3MM) Auger feature to optimize UV-O3 exposure time, and minimize the interfacial layer growth of silicon and germanium oxides.

The electrical properties and stability of the hafnium silicate/Si0.8Ge0.2(100) interface

“…This film was grown by sputter deposition of a ϳ1.3-nm-thick, hafniumsilicide film onto clean Si 0.8 Ge 0.2 (100) followed by insitu UV-ozone oxidation at room temperature. 20 The fully oxidized HfSiO film is 3-nm thick as verified by cross-sectional HRTEM. 20 By using ex-situ XPS analysis, it was confirmed that, within the detection limit of the technique, the oxidation parameters used did not lead to the growth of a low-κ interfacial-oxide layer because of the oxidation of the Si 0.8 Ge 0.2 (100) substrate.…”

“…20 The fully oxidized HfSiO film is 3-nm thick as verified by cross-sectional HRTEM. 20 By using ex-situ XPS analysis, it was confirmed that, within the detection limit of the technique, the oxidation parameters used did not lead to the growth of a low-κ interfacial-oxide layer because of the oxidation of the Si 0.8 Ge 0.2 (100) substrate. 20 The C-V curve with the unannealed HfSiO film (Fig.…”

“…Hafnium silicate (3-nm thick) films were grown on these Si 0.8 Ge 0.2 (100) substrates at room temperature by direct current (DC)-magnetron sputtering from a pressed-powder hafnium-silicide target with subsequent in-situ UV-O 3 oxidation. 20 The UV-O 3 oxidation conditions were optimized to minimize the formation of a Si x Ge 1-x O 2 interfacial layer within the detection limit of x-ray photoelectron spectroscopy (XPS), by monitoring the Ge(L 3 MM) x-ray-excited Auger feature. 20 The XPS spectra presented in this paper were acquired with a standard Al Kα x-ray source, operated at a power of 280 W, and an electrostatic analyzer, operated in the constant passenergy mode (20 eV).…”

“…20 The UV-O 3 oxidation conditions were optimized to minimize the formation of a Si x Ge 1-x O 2 interfacial layer within the detection limit of x-ray photoelectron spectroscopy (XPS), by monitoring the Ge(L 3 MM) x-ray-excited Auger feature. 20 The XPS spectra presented in this paper were acquired with a standard Al Kα x-ray source, operated at a power of 280 W, and an electrostatic analyzer, operated in the constant passenergy mode (20 eV). All spectra were referenced to the Si 2p feature from the Si 0.8 Ge 0.2 (100) substrate at 99.5 eV.…”

“…10,[16][17][18][19] We previously demonstrated that ultrathin hafnium-silicate films could be produced in direct contact with Si x Ge 1-x (100) substrates at room temperature by ultraviolet (UV)-O 3 oxidation of sputterdeposited hafnium silicide. 20 In this paper, we report the electrical properties of the hafnium silicate (HfSiO) films deposited on Si x Ge 1-x (100) using the UV-O 3 oxidation approach, and the effect of post-oxidation annealing (POA) in N 2 and postmetallization annealing (PMA) in forming gas. Implications for the introduction of hafnium silicate as a viable gate dielectric for SiGe-based devices are also discussed.…”