Solder transfer of lead zirconate titanate (PZT) thin films

Functional ceramic thin films such as lead zirconate titanate (PZT) are of interest for a wide range of miniaturized devices. However the high processing temperatures of the films make integration of them into such devices challenging. Transfer of these films can allow integration onto substrates that are incompatible with the film deposition processes, but is hampered by the difficulty of detaching the film from the growth substrate. We describe a transfer process for PZT films grown on Ti/Pt coated Si wafers, in which the films are solder bonded onto a target substrate and lifted off in one step, by thermal stress induced separation of the PZT-Pt interface. In order to study effects of the transfer process on the integrated films, polarization-electric field (P-E) hysteresis loop, dielectric constant, and loss tangent measurement were made on both the transferred and as-deposited films. The transferred films show low mechanical damage, ferroelectric hysteresis with an `imprinted´ polarization, reduced permittivity, and slightly increased loss tangent at low frequencies (~ 1 kHz). This transfer technique is potentially a revolutionary approach which could be broadly applicable to a variety of ceramic thin film materials, film growth methods, device geometries, and substrate combinations.