Sol–gel preparation of yttria-stabilized zirconia thin films and transfer to polycarbonate substrates

Abstract

Yttria-stabilized zirconia (YSZ) precursor gel films with or without acetylacetone (AcAc) were prepared on polyimide-polyvinylpyrrolidone layers that were deposited beforehand on Si(100) substrates. The gel-film deposition and firing were cycled, and the resulting YSZ films were transferred to polycarbonate (PC) substrates by heating the film and pressing the PC substrates on it. The fractions of the area of the film that was successfully transferred and that failed to be transferred were evaluated by image analysis. Higher firing temperatures were effective in decreasing the porosity, while they increased the fraction of the area of the film that failed to be transferred, which may be caused by an increase in adhesion at the YSZ/Si(100) interface. AcAc in solutions was also effective in decreasing the porosity, but reduced the successful transfer area fraction, which may result from the reduced film/PC adhesion due to the lower surface roughness of the film. However, the transfer area fraction could be increased from 5 to 74% when the uniaxial pressure on transfer was increased from 0.16 to 8.66 MPa for the film of 8% porosity prepared from the AcAc-containing solution via final heat-treatment at 900 °C. Such a high pressure was ineffective, on the other hand, for the film of a lower porosity of 4% fired at 1000 °C, suggesting that the optimization of preparation conditions that allows low porosity at low firing temperatures would be one of the keys for realizing the transfer of dense films.