Fabrication of rf-Sputtered Barium Titanate Thin Films

Abstract

Barium titanate (BaTiO3) was deposited onto Pt foil, and onto thin-film Pt and Pt-Rh electrodes on sapphire, and counterelectroded to complete metal-dielectric-metal structures. Dielectrics (5000–60 000 Å) were deposited at substrate temperatures from 23 ° to 1000 °C, some fired in air at temperatures to 1400 °C after deposition, the films providing a wide range of dielectric constants (16–1900). Onset of BaTiO3 crystal growth was detected at 500 °C, a reduced BaTiO3 detected at 1000 °C, and constant Ba/Ti ratios measured over the deposition temperature range. Capacitance increase with temperature was essentially linear, with the fired dielectrics showing minimum slope. Tanδ varied from 0.005 for amorphous films to 0.065 for films with highest dielectric constants, with related dielectric strengths of 1.8×106 to ≈0.15×106 V/cm, respectively. Substrate, electrode, and process limitations for capacitor fabrication are defined.

Electrical properties of low temperature deposited amorphous barium titanate thin films as dielectrics for integrated capacitors

“…At room temperature (25 -C) and for f = 100 kHz we have eV = 18.5, eW = 0.07, and tand å4 Â 10 À 3 . These values are similar to the ones found by other authors for sputtered a-BaTiO 3 [1,2,5]. At room temperature the dielectric constant increases from eV = 18.5 at 100 kHz to eV = 23 when the frequency decreases down to f = 0.1 Hz.…”

“…This corresponds to a conductivity of 4 Â 10 À 16 S/ cm, very close to the one we measured. When the thickness is reduced the general trend is to observe an increase in the conductivity [1,3]. We indeed observed this effect as we measured 10 À 15 , 5Â 10 À 15 and 10 À 11 S/cm for 0.85, 0.30 and 0.16 Am thick films respectively (the dielectric constant is almost constant).…”

Thickness dependence of room temperature permittivity of polycrystalline BaTiO3 thin films by radio-frequency magnetron sputtering

“…Although the 2100 Å film exhibited the weak ferroelectricity, Table I indicates that its rt is comparable to the highest rt of BaTiO 3 thin films reported by other investigators. According to Shintany et al 10 and Pratt et al 8,9 only films deposited or postheat treated at above 1000°C had rt values higher than 1000. Considering that the in situ deposition temperature used in this present study is only 700°C, the rt value of the 2100 Å film is very high.…”

“…3 The most remarkable property of BaTiO 3 is its high permittivity 3-5 and a significant amount of research has dealt with the preparation of BaTiO 3 thin films with high permittivity. [6][7][8][9][10][11][12][13][14][15] Most of these works, however, failed to obtain BaTiO 3 thin films with high permittivity in comparison to BaTiO 3 ceramics; the room temperature permittivity of BaTiO 3 ceramics is known to be greater than 2000 4,5 whereas BaTiO 3 thin films usually have the permittivities in the range of a few hundred.…”

Characterization and leakage current density of radio frequency magnetron sputtered nanocrstalline SrTiO3 thin films

“…By this process, in general, stoichiometric composition of the deposited materials can be maintained as transferred from source to substrate [7]. In the present study, the characterization and leakage current density of SrTiO 3 thin films deposition on Pt/Ti/SiO 2 /Si substrates prepared at 500 C by RF magnetron sputtering were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), scanning transmission electron microscope (STEM), electron diffraction (ED), profilometer, capacitance-voltage, and current-voltage measurement.…”