Structural, interfacial and optical characterization of ultrathin zirconia film grown by in situ thermal oxidation of sputtered metallic Zr films

Abstract

High dielectric constant ZrO2 gate dielectric thin films have been prepared by means of in situ thermal oxidation of sputtered metallic Zr films. XRD reveals that the as-oxidized samples are amorphous, but can be made polycrystalline with a highly ()-preferential orientation by increasing the annealing temperature. AFM measurements confirm that high temperature annealing results in increase of the roughness root mean square value of the films. The growth and properties of the interfacial SiO2 layer formed at the ZrO2/Si interface are observed by using Fourier transform infrared spectroscopy. It has been found that the formation of the interfacial layer depends on the post-deposition annealing temperature. On the basis of a parametrized Tauc–Lorentz dispersion model, the optical properties of the as-oxidized and annealed films related to the annealing temperature are systematically investigated by spectroscopic ellipsometry. The increase in the refractive index and decrease in extinction coefficient with increase of the annealing temperature are discussed in detail.

Growth and electrical properties of spin coated ultrathin ZrO2 films on silicon

“…The lower dielectric constant values of the films compared to that of bulk ZrO 2 ($25) may be attributed to the monoclinic phase and possible formation of Zrsilicide and/or SiO x at the interface of the films. 9,12,17,18,22 The dielectric constant values are in good agreement with the ultra-thin ZrO 2 films deposited by many other researchers. 9,11,12 Fig .…”

“…9,12,17,18,22 The dielectric constant values are in good agreement with the ultra-thin ZrO 2 films deposited by many other researchers. 9,11,12 Fig . 6 shows the leakage current density the ZrO 2 films as a function of applied voltage.…”

“…[1][2][3][4][5][6] Out of these application, present day MOS technology demands deposition of ultrathin metal oxide films, having thickness 50 nm or less, to replace SiO 2 as gate insulator. [7][8][9][10][11][12][13][14] Although the integration of many of these oxide films on silicon remains a huge challenge mainly due to the stability and interfaces of these oxide with the Si substrate, ZrO 2 is one of the most promising material in the field of MOS technologies because of its excellent thermal, chemical, and mechanical stability with silicon, high dielectric constant, and large band gap. [7][8][9][10][11]15,16 Ultrathin ZrO 2 films, for MOS devices applications, are mainly deposited by vacuum-based methods like evaporation, 17,18 sputtering, 1,12,14,16,19 metal-organic chemical vapor deposition (MOCVD), 7,20 atomic layer deposition (ALD), 9,11,13,21,22 and pulsed laser-ablation deposition (PLD).…”

Optical properties and structural characterization of bias sputtered ZrO2 films

“…At the bias above −80 V, an additional peak corresponding to SiO 2 can be found which probably due to the combination of the silicon and oxygen atoms through re-sputtering of the growing film under higher bias. The diffusion of oxygen through the ZrO 2 films is also enhanced under high deposition temperature, as ZrO 2 films have been previously reported to be an oxygen ion conductor and have high oxygen diffusivity [12]. The tetragonal diffraction peak is the same prominent at higher bias under 300 • C deposition as the behavior of the films deposited at room temperature on glass substrate.…”

Integrations and challenges of novel high-k gate stacks in advanced CMOS technology

“…Early work on alternative gate dielectrics was focused on TiO 2 , Ta 2 O 5 , and BaSrTiO 3 , which were inherited from dynamic random access memory (DRAM) capacitor dielectric research [57][58][59][60]. Recently, Hf(Zr)-based oxides, including HfO 2 , ZrO 2 , and their silicates have emerged as promising candidates for high-k dielectrics because of their excellent thermal stability with Si [7,11,[61][62][63][64][65][66]. Furthermore, the mobility of CMOS devices using Hfbased high-k gate dielectrics has been improved significantly [67], almost matching that of nitride oxide at an EOT of $1 nm.…”