Laser transfer processing of functional ceramic films

• Main Author: James, Craig William
• Published: University of Leeds 2011
• Subjects: 620.14
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.589013

The incorporation of ferroelectric films, traditionally fabricated at high temperatures, with modern low temperature substrates has been an ongoing issue for the electroceramic community in recent years. The majority of ferroelectric film fabrication techniques utilise high temperature processing, with required temperatures ranging from 550-700 DC, for the production of thin films, to ",900-1200 DC, for thick films and bulk ceramics, with some fiuxes allowing fabrication at 850 DC. Some lead free electroceramics require processing at even higher temperatures. The limit of thermal stability for the majority of desired substrates lies significantly lower than these required processing temperatures. Platinised silicon has been shown to stable to maximum temperatures of 750 DC, with polymer and many semi-conductor substrates effective only from 150-350 DC. Clearly, direct deposition of ferroelectric films onto these family of substrates can not be realised at this time. Laser transfer processing (LTP) has recently been shown to be a viable alternative approach to these integration challenges. Films are initially fabricated on substrates stable to high temperatures (commonly single crystal sapphire), before bonding to low temperature, electrically useful substrates. The fabrication substrate is then removed by using a UV laser pulse to seperate the film and original substrate. In this thesis, lead zirconate titanate (PZT) thin films have been produced from a sol- gel technique. Thick-films have been deposited by spin coating a hybrid particle sol-gel slurry and by a conventional tap-casting route. The films were then transferred to a second substrate, usually platinised silicon but polymer-based substrates were also examined, using a KrF excimer laser (248 nm wavelength) to delaminate the films from the sapphire fabrication substrate. A primary aim was to understand the effects of LTP on interfacial structure and the electrical properties of the film samples.