Polycrystalline copper films thicker than 100 nm were evaporated on silicon wafers with their native oxide under ultrahigh vacuum conditions leading to an rms roughness of ~2 nm of the copper film. X-ray photoelectron spectroscopy (XPS) revealed a clean copper surface with only traces of oxygen. The samples were exposed to air, leading to an oxide film consisting of CuO. TiO films were subsequently deposited onto the oxidized copper films from a resistively heated tungsten boat with the substrate at room temperature. The TiO films exhibited good adherence and were amorphous. XPS measurements revealed that the TiO films were contamination-free and that the first layers of TiO reduced the thin native oxide of the copper substrate from Cu(II) into Cu(I) or Cu(0) and transformed the TiO into TiO2 at the interface.

Ba(Ti,Zr)O3 thin films were grown hydrothermally on silicon substrates coated with sputtered a Ti-34 at.%Zr metallic alloy thin film. To ensure the formation of Ba(Ti,Zr)O3 under the hydrothermal conditions at 150°C, the concentration of the Ba(OH)2 had to be greater than 0.25 M. Preliminary capacitance measurement revealed a dielectric constant of 200 in Ba(Ti,Zr)O3 films of approximately 320 nm. The formation mechanism is discussed.

Ti–Zr alloy thin films of 20–60 nm in thickness were evaporated on Pt-coated silicon wafers. The films exhibited a layered Ti–Zr depth distribution. The films were then treated hydrothermally in 0.25 M Ba(OH)2 at 150 and 200 °C for 4–8 h. Films treated at 150 °C did not exhibit reflections from the Ba(TixZr1−x)O3 perovskite structure by x-ray diffraction, although a slight barium content was detected by x-ray photoelectron spectrometry. On the other hand, the films treated hydrothermally at 200 °C revealed reflections corresponding to perovskite Ba(TixZr1−x)O3. These films exhibited a homogeneous titanium and zirconium depth distribution, as shown by x-ray photoelectron spectroscopy and Auger depth profiles, proving that either titanium or zirconium ions diffuse during the hydrothemal treatment. The initial Ti–Zr film was completely consumed during the hydrothermal process, leading to a film of homogeneous composition (Ba, Ti, and Zr) up to the interface with the platinum layer.

Barium titanate microstructures are fabricated on silicon(100)/platinum substrates coated with photoresist and titanium by a combination of hydrothermal and lift-off techniques. The microstructures of 10μm width are well defined. The barium titanate films grow in its cubic phase. Analysis by means of x-ray diffraction and scanning electron microscopy shows that only a part of the titanium layer is affected by the hydrothermal reaction. This limitation may be overcome by application of electrochemistry.

BaTiO3 thin films, 50–60 nm in thickness, were evaporated in Ultra High Vacuum as well as under 1 mPa O2 pressure onto Si/SiO2 (30 nm) wafers. The substrate temperature during the evaporations was approximately 70 °C. The films were flash annealed in oxygen at 500 °C. The interfacial reactions were studied by XPS and AES Ar ion assisted depth profiling, and by RBS. Interdiffusion took place even at 70 °C. The XPS/AES depth profiles suggested strong interdiffusion, with Ba being the dominant moving species. The SiO2/BaTiO3 interface smears out with significant Ba concentrations up to half of the SiO2 thickness. Ti diffusion is remarkably lower. Barium is detected up to the SiO2/Si interface.

The influence of controlled potential conditions on the structure and phases of BaTiO3 films grown on titanium by the hydrothermal-electrochemical method was studied. The experiments were conducted using a three electrode high pressure electrochemical cell in a 0.2 M Ba(OH)2 electrolyte at 150 °C. The spontaneous initial nucleation linked to pure hydrothermal BaTiO3 formation was inhibited by cathodically protecting the titanium electrode since its immersion in the electrolyte. The application of initial nucleation pulses of varying cathodic potentials affected the grain size of the deposit. The growth of tetragonal BaTiO3 was achieved combining the initial inhibition of the pure hydrothermal growth, followed by nucleation under controlled potentiostatic conditions.