Thermodynamic considerations in the stability of binary oxides for alternative gate dielectrics in complementary metal–oxide–semiconductors

Abstract

A number of binary oxides have been predicted to be thermodynamically stable in contact with Si and are candidates to replace SiO 2 in CMOS. However, reactions leading to the formation of interfacial silicide, silicate or SiO 2 layers have been reported when these oxides are exposed to high temperatures during device processing. Different pathways have been proposed in the literature to explain these reactions. In this paper, a thermodynamic analysis of the proposed reactions is performed. The analysis includes gaseous species, because typical gate dielectrics are ultra-thin layers and diffusivities for species from the surrounding atmosphere, such as oxygen, may be high. Furthermore, nonstoichiometry of the high-k oxide, as may be resulting from nonequilibrium deposition processes or reducing atmospheres during processing is also considered. Studies are proposed to distinguish between possible reaction mechanisms. Finally guidelines for stable interfaces are presented.3

Interfacial reaction in ZrO2/Si gate-stack structure probed by photoemission spectroscopy combined with combinatorial annealing system

“…The SiO gas is related to each reaction [13][14][15]. Thermal stability in reactions (1)- (3) can be estimated thermodynamically using Gibbs' free energies.…”

“…3. In order to estimate the difference in Gibbs' free energy (∆G) for each reaction, SiO-gas contributions are evaluated as the term for the gas, −RT ln P SiO [13][14][15]. Interfacial reactions occur by following three steps.…”

Effects of thermal treatment and fluoride ion doping on surface and catalytic properties of NiO–ZrO2catalysts

“…Moreover, zirconia is claimed to be a good catalyst that has acidic, basic, reducing and oxidizing surface properties. In modern industry, zirconia has been widely used in various fields such as high-temperature fuel cells [3,4], structural ceramics [5], gas sensors [6,7], and as an insulator in metal oxide semiconductor devices [8,9]. Zirconia was used also as a support and/or catalyst material with unique properties in a great variety * E-mail: rehamfattah2012@gmail.com of reactions.…”

Detection and mobility of hafnium in SiO2

“…In HfO 2 gate dielectric stacks, SiO 2 -rich interfacial layers are often present at the interface with Si, either as a result of oxidizing growth or annealing conditions [2] or because they are intentionally grown as a nucleation layer before high-k deposition [3]. The chemistry of these interfacial layers and the nature of their interaction with the HfO 2 film are of great practical interest as they determine the electrical and dielectric properties of the gate stack.…”