Remote Plasma Enhanced-Metal Organic Chemical Vapor Deposition of Zirconium Oxide/Silicon Oxide Alloy, (ZrO₂)₁-(SiO₂)_1−x (x:≤0.5), Thin Films for Advanced High-K Gate Dielectrics

Abstract

A remote plasma enhanced-metal organic chemical vapor deposition (RPE-MOCVD) process was developed for the preparation of non-crystalline (ZrO2)x-(SiO2)1−x (x ≤ 0.5) alloys, targeting the compound composition ZrSiO4with k ∼ 12.5. Shifts in Si LVV and Zr LMM AES energies with respect to elemental values showed that the deposited film was a fully-oxidized zirconium/silicon alloy. FTIR results were consistent with AES, and a Zr-O-Si bonding mode was identified in the spectra. The films were amorphous before and after RTA at 900°C for 30 sec, as monitored via RHEED. Optical absorption measurements indicated the onset of band-to-band transitions at an energy of approximately 6 eV. Finally, C-V testing showed that the films were insulating.

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

“…1 Insulators with higher dielectric constants offer potential for increased capacitance in physically thicker films, providing a possible way to reduce direct tunneling. 2 MOS capacitors with SiO 2 -rich Zr and Hf silicates with 3-6 at. % Zr͑Hf͒ have been reported to have increased dielectric constants and reduced tunneling currents.…”

“…Figure 2 displays absorbance for Zr silicate films prepared by remote plasma enhanced chemical vapor deposition. 2,7 Alloy compositions were determined to Ϯ0.05 by Rutherford backscattering spectrometry. Spectra of as-deposited films and films annealed for 30 s in Ar at temperatures to 800°C ͑not shown͒ are essentially the same, whereas spectra of films annealed at 900°C are markedly different.…”

“…This is not a limitation in thin film silicates deposited at temperatures Ͻ500°C. [1][2][3][4][5]7 The analysis below applies to these films, as well as those prepared at low temperatures, and subsequently processed at temperatures Ͻ800°C. Capacitors with Zr͑Hf͒ silicate dielectrics in Refs.…”

Local Bonding, Phase Stability and Interface Properties of Replacement Gate Dielectrics, Including Silicon Oxynitride Alloys and Nitrides, and Film ‘Amphoteric’ Elemental Oxides and Silicates

“…Homogeniety in bulk silicate glasses quenched from high temperatures is limited by chemical phase separation, and in many instances homogeneous glasses are obtained only at relatively low metal oxide compositions, <5-10 mol percent. This is not a limitation in thin film silicates deposited at temperatures <500°C [22,23,[27][28][29][30], The analysis presented below applies to these films, as well as films prepared at low temperatures, and subsequently processed at temperatures <800°C. The capacitors with Zr(Hf) silicate dielectrics in Refs.…”

“…This causes the coordination number of the Zr-atoms to increase above four, including edge-as well as corner-connected bonding arrangements. In crystalline silicates, the Zr 4+ ions have a coordination of 8, with each Zr-atom making edge-connections to four different tetrahedral SiO 4 4-groups [22,28]. The respective Zr-O and Si-O bond lengths are ~0.22 nm and 0.16 nm.…”