Zr Silicate Alloys Research Articles

Strain‐reducing chemical bonding self‐organizations in nanocrystalline composites and non‐crystalline glasses and thin films

AbstractThis article identifies a length scale for spinodal decomposition of Hf and Zr silicate alloys. This has provided important insights into chemical bonding self‐organizations in non‐crystalline alloys as well, in particular for the intermediate phase regime of chalcogenide alloys. Additional insights into nanolength scales for chemical bonding self‐organizations; also extending into the medium range order (MRO) regime in network glasses are identified through comparisons between the first sharp diffraction peaks in oxide and chalcogenide compounds and alloys. These length scales are based on the extraction of real space correlation and coherence lengths, R and L, respectively. These comparisons have identified bond‐ionicity related differences in the short range order which play a significant role in promoting differences in MRO between oxides and chalcogenides, including bulk glasses as well as thin films.

Network disruption and modification in arsenic and germanium chalcogenides by the addition of univalent metal sulfides and selenides: Comparisons with network disruption and modification in zirconium silicate alloys

The addition of the tetravalent metal oxide, ZrO2, into non-crystalline (nc-) SiO2 to form thin film nc-Zr silicates, and the univalent metal sulfides (selenides), (Cu,Ag)2S(Se), into nc-As2S(Se)3 and -GeS(Se)2 networks to form nc-thin film and/or bulk Ag and Cu chalcogenide alloys are compared. The bonding coordination of representative metal-atoms, generally (i) 4 for Cu, (ii) 3 for Ag, and (ii) up to 8 for Zr, do not obey the Mott 8-N rule bonding for the Si, Ge, As, and O and chalcogenide atoms in their respective host networks. These break-downs of 8-N bonding for metal atoms are accompanied by increases in the coordination of O-atoms from 2 to 3 in Zr silicate alloys to accommodate increased bond ionicity, and increases of 2–4 for S(Se)-atoms in Ag and Cu chalcogenide alloys to accommodate covalent bonding requirements in tetrahedral arrangements.

Chemical phase separation in Zr silicate alloys: an EXAFS study distinguishing between phase separation with and without XRD detectable crystallization

Chemical phase separation at processing temperatures is an important issue for integration of Zr and Hf silicates alloys into advanced CMOS devices. Chemical phase separation into ZrO2 and SiO2 has been detected by different spectroscopic techniques, including Fourier transform infra red, x-ray photoelectron, and x-ray absorption spectroscopy, as well as x-ray diffraction and high resolution transmission electron microscopy imaging. Comparisons between these techniques for Zr silicates identify an unambiguous approach to distinguishing between chemical phase separation with different degrees of micro- and nano-crystallinity. This is important since all modes of chemical separation degrade the dielectric properties required for high-K applications.

Chemical phase separation in Zr silicate alloys: a spectroscopic study distinguishing between chemical phase separation with different degrees of micro- and nano-crystallinity

Chemical phase separation is an important issue for process integration of non-crystalline Zr and Hf silicate alloys into advanced microelectronic devices. Chemical phase separation of Zr silicates into ZrO 2 and SiO 2 has been detected by different spectroscopic techniques, including Fourier transform infrared, X-ray photoelectron, X-ray absorption, and extended X-ray absorption fine structure spectroscopies, as well as X-ray diffraction and high resolution transmission electron microscopy imaging. This combination of techniques identifies an unambiguous way to distinguish between chemical phase separation with different degrees of micro- and nano-crystallinity. This is important since all modes of chemical separation degrade dielectric properties required for device applications.

Chemical phase separation in Zr silicate alloys: a spectroscopic study distinguishing between chemical phase separation with different degree of micro- and nano-crystallinity

Chemical phase separation at processing temperatures is an important issue for integration of Zr and Hf silicates alloys into advanced CMOS devices. Chemical phase separation into ZrO 2 and SiO 2 has been detected by different spectroscopic techniques, including Fourier transform infrared, X-ray photoelectron, and X-ray absorption spectroscopy, as well as X-ray diffraction and high resolution transmission electron microscopy imaging as well. Comparisons between techniques for Zr silicates identify an unambiguous approach to distinguishing between chemical phase separation with different degrees of micro- and nano-crystallinity. This is important since all modes of chemical separation degrade dielectric properties required for high- K applications.

Spectroscopic study of chemical phase separation in zirconium silicate alloys

This article presents a comprehensive spectroscopic study of chemical phase separation in zirconium silicate alloys, (ZrO2)x(SiO2)1−x, using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, extended x-ray absorption fine structure spectroscopy, and near edge x-ray absorption spectroscopy. These measurements are complemented by measurements of x-ray diffraction and high resolution transmission electronic microscopy imaging. This combination has been applied to Zr silicate alloys, providing the first comprehensive comparisons of the relative sensitivities of these spectroscopic techniques applied to micro- and nanoscale chemical phase separation of high-k dielectric alloys.

Band offset energies in zirconium silicate Si alloys

Transition metal silicates, (ZrO 2) x (SiO 2) 1− x , with dielectric constants, k>10 have been proposed as alternative dielectrics for advanced Si devices. Studies by X-ray absorption, X-ray photoelectron and Auger electron spectroscopy are combined to identify the compositional variation of the valence and conduction band offset energies with respect to Si in Zr silicate alloys. The minimum conduction band offset energy, associated with localized Zr 4d ∗-states, is ∼1.4 eV, and is independent of alloy composition, while valence band offsets decrease monotonically with increasing ZrO 2 content. Differences between the coupling of tunneling electrons to localized Zr 4d ∗ and extended Si 3s ∗ states, characterized by respective tunneling masses of ∼0.5 m o and ∼0.2 m o, combine to contribute to a minimum in the direct tunneling current in the mid-silicate-alloy composition range, x∼0.4–0.6.

Electronic structure of transition metal high-k dielectrics: interfacial band offset energies for microelectronic devices

Transition metal silicates, (ZrO2)x(SiO2)1−x, have dielectric constants k>10 that make them attractive for advanced Si devices. Band offset energies relative to Si are an important factor in determining tunneling leakage current, and internal photoemission. Studies by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and X-ray absorption spectroscopy (XAS) are combined with ab initio calculations to identify the compositional variation of the band-gap, and valence and conduction band offset energies of Zr silicate alloys with respect to Si. The minimum conduction band offset, due to Zr 4d∗ states, is shown to be independent of alloy composition, while valence band offsets decrease monotonically with increasing ZrO2 content. The implications of these results for direct tunneling are discussed.

Microscopic model for enhanced dielectric constants in low concentration SiO2-rich noncrystalline Zr and Hf silicate alloys

Dielectric constants, k, of Zr(Hf) silicate alloy gate dielectrics obtained from analysis of capacitance–voltage curves of metal–oxide–semiconductor capacitors with 3–6 at. % Zr(Hf) are significantly larger than estimates of k based on linear extrapolations between SiO2 and compound silicates, Zr(Hf)SiO4. Analysis of infrared spectra of Zr silicate alloys with 3–16 at. % Zr indicates increases in the coordination of Zr to O atoms from 4 to approximately 8 with increasing Zr content. The major contributions to enhancements in k in these low Zr(Hf) content alloys are explained by a transverse infrared effective charge that scales inversely with increasing Zr–O bond coordination.