Dielectric properties of noncrystallineHfSiON

Abstract

The dielectric properties of noncrystalline hafnium silicon oxynitride (HfSiON) films with a variety of atomic compositions were investigated. The films were deposited by reactive sputtering of Hf and Si in an O, N, and Ar mixture ambient. The bonding states, band-gap energies, atomic compositions, and crystallinities were confirmed by X-ray photoelectron spectroscopy (XPS), reflection electron energy loss spectroscopy (REELS), Rutherford backscattering spectrometry (RBS), and X-ray diffractometry (XRD), respectively. The optical (high-frequency) dielectric constants were optically determined by the square of the reflective indexes measured by ellipsometry. The static dielectric constants were electrically estimated by the capacitance of Au/HfSiON/Si (100) structures. It was observed that low N incorporation in the films led to the formation of only Si-N bonds without Hf-N bonds. An abrupt decrease in band-gap energies was observed at atomic compositions corresponding to the boundary where Hf-N bonds start to form. By combining the data for the atomic concentrations and bonding states, we found that HfSiON can be regarded as a pseudo-quaternary alloy consisting of four insulating components: SiO 2 , HfO 2 , Si 3 N 4 , and Hf 3 N 4 .The optical and static dielectric constants for the films showed a nonlinear dependence on the N concentration, whose behavior can be understood in terms of abrupt Hf-N bond formation.

Complex investigation of multilayer nanostructure of a-Si/SiO1.9 by probe and spectroscopic analysis techniques. Visualization of the band structure. Studying of the band structure of the suboxide border layers

“…Calculations were carried out by a method similar to that described by several authors. [15,16] For a more accurate determination of numerical values the second derivative of the function of electron energy loss was also considered. Summary of the forbidden bandwidth and the position of the peaks of suboxide states [17] are shown in Table 4.…”

Composition dependence of electronic structure and optical properties of Hf1−xSixOy gate dielectrics

“…It has been reported that the optical dielectric constants decrease with the increase in the band gap energy, which is due to the fact that the optical dielectric constant originating from electronic polarizability is strongly dependent on the width of the band gap energy and is nearly independent of the origin of the band gap, i.e., the atomic composition. 27 This result suggests that the evolution of the optical dielectric constants is attributed to the change in the optical band gap with the increase in the silicon atomic composition. Figure 5͑b͒ presents the spectra of the imaginary ͑ 2 ͒ part of the dielectric functions for samples S1, S2, S3, and S4.…”

Hafnium-Based Gate Dielectric Materials

“…For any relative Hf concentration, larger nitrogen [73] incorporation generally increases the dielectric constant. Considering that Si 3 N 4 has a larger k-value (about 7.8) than that of SiO 2 , nitrogen incorporation is expected to enhance the dielectric constant; however, Koike et al claimed that the dielectric constant increases drastically with Hf-N bond formation for a certain [N] level depending on Hf content in the film [97]. The dotted line in Fig.…”

“…3.10 Average dielectric constant of the film just after deposition and after the phase separation at hightemperature annealing [88] The nitrogen concentration criterion for keeping the thermal stability of HfSiO is definitely dependent on the hafnium content in the film. The lower limit of nitrogen concentration that can sustain the amorphous structure, avoiding the phase separation and crystallization, was investigated extensively for the case of 1,065°C spike annealing in nitrogen ambient [97]. The lower limit increases gradually when Hf content increases in the film, however, for films with Hf/Hf+Si larger than 80 %, the lower limit increases dramatically.…”

“…This is also called the 'optical dielectric constant' because it is the dielectric constant in the optical frequency region. Knowing that the reflectivity of HfO 2 is about 2.1 [17], the electronic polarization component of this material is estimated to be around 4.4. Since this value is small compared to the static dielectric constant value [1,2,14], one can assume that the reason for the high static dielectric constant of this material resides in a large ionic polarization.…”