The interfaces between metal organic chemical vapor deposited PbTiO3 thin films, and various diffusion barrier layers on Si substrates, were investigated by means of transmission electron microscopy. Thin films of polycrystalline TiO2, amorphous TiO2, ZrO2 and TiN were deposited between the PbTiO3 and the Si substrate. The deposition of PbTiO3 thin films directly onto bare Si substrates produced Pb silicate layers at the interface, regardless of the deposition conditions. The TiO2 films were converted to PbTiO3 via reaction with diffused Pb and O ions during PbTiO3 deposition at a substrate temperature of 410C. Further diffusion of Pb and O induced the formation of a Pb silicate layer at the interface. The ZrO2 did not seem to react with Pb and O during PbTiO3 deposition at the same temperature, but the Pb and O ions which diffused through the ZrO2 layer formed a Pb silicate layer between the ZrO2 and the Si substrate. The TiN films did not seem to react with Pb and O ions during the deposition of PbTiO3 at 410C, but reacted with PbTiO3 to form a Pb-deficient pyrochlore during post-deposition rapid thermal annealing at 700C. However, TiN could effectively block the diffusion of Pb and O ions into the Si substrate, and the formation of Pb silicate at the interface.

C.S.Hwang, H.J.Kim: Journal of the American Ceramic Society, 1995, 78[2], 337-41