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We prepared yttria‐stabilized zirconia (YSZ) and titania crystalline thin films on polycarbonate (PC) substrates by the sol‐gel transfer technique that we have developed recently. Precursor gel films were deposited by spin‐coating on a polyimide/polyvinylpyrrolidone mixture layer on Si(100) substrates, and then were calcined at 600°C. The spin‐coating and the calcination were cycled, followed by final firing at 600–1000°C, to obtain 140–190 nm thick, YSZ and titania crystalline thin films. The film densification progressed as the final firing temperature increased, where the porosity calculated from the refractive index decreased down to a few percent. The film thus obtained was heated at 190°C on a hot plate, and a PC substrate was pressed on the film to transfer it to the PC substrate. The transferability quantified by image analysis of the film area was found to be significantly different between the YSZ and titania films. In the case of YSZ films, the area of silicon that was fractured and adhered to the transferred film increased significantly with increasing firing temperature, leading to a decrease down to 0% in the fraction of the successful transfer area without such a damage. On the other hand, the fraction of the successful transfer area remained around 90% irrespective of the firing temperature for the titania films. The surface of the titania films that were fired at 800–1000°C and transferred to PC substrates had voids of several tens nm scale, which may have been formed during anatase‐to‐rutile phase transformation. We thought that the reduced titania/Si(100) contact area due to such void formation facilitated the delamination of the titania films from Si(100) substrates. High temperature firing, which promotes crystallization and densification of films, thus affects differently the film transferability to plastic substrates, depending on the type of films. The work also suggested possible use of titania films as release‐assisting layers. [ABSTRACT FROM AUTHOR]

Previously, we demonstrated that solgel-derived glass and ceramic thin films show a decrease in in-plane residual tensile stress during storing in humid atmosphere at room temperature. To clarify the mechanism, we prepared SiO2 glass films on Si(100) wafers via spin-coating followed by firing and obtained in-plane stress by measuring the substrate curvature. The SiO2 film fired at 600 °C showed a decrease in tensile stress during storing but showed recovery when heated afterward at 300 °C. We detected an increase in the infrared O–H absorption peak area as well as in the film thickness during storing, the latter of which was detected by in situ ellipsometry for the SiO2 film fired at 600 °C. On the other hand, when fired at 880 and 885 °C, the SiO2 films gained "compressive" residual stress, which slightly increased with time during storing. Based on these observations the decrease in tensile stress during storing has been confirmed to be caused basically by the film expansion induced by water adsorption. The SiO2 film fired at 600 °C showed recovery in stress on heating at 300 °C, which was incomplete in contrast to the CeO2 film that showed complete recovery as reported previously. Such recovery in stress was accompanied by decrease and turning back of the O–H absorption peak are to original values, the latter of which was incomplete in the SiO2 film but complete in the CeO2 film. These results on stress recovery and IR absorption suggest that besides water "adsorption," water "absorption" cannot be ruled out for the SiO2 film as the partial cause of the decrease in "tensile" stress during storing. [ABSTRACT FROM AUTHOR]