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EPSRC Reference: EP/C519914/1
Title: Processing Of Low-Environmental Impact Ferroelectric Thin Films for Improved Integration in Microelectronic Sytems
Principal Investigator: Miles, Professor RE
Other Investigators:
Jha, Professor A Milne, Dr SJ
Researcher Co-Investigators:
Project Partners:
Filtronic
Department: Electronic and Electrical Engineering
Organisation: University of Leeds
Scheme: Standard Research (Pre-FEC)
Starts: 01 January 2005 Ends: 30 June 2006 Value (£): 101,942
EPSRC Research Topic Classifications:
Electronic Devices & Subsys. Materials Characterisation
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
For many decades, and up to the present day, the most commonly used ferroelectric, pyroelectric, piezoelectric and electro-optic materials contained lead oxide; an important example being lead zirconate titanate (PZT). For health and environmental reasons, it is essential that safer materials be used in the future. Alternatives must exhibit physical and electrical properties that are comparable to their Pb-based predecessors, although changes are likely to be required for the next generation of devices which may emphasise different aspects.The films which we are interested in utilizing include (Ba,Sr)TiO3 for use in future microwave communications systems allowing items such as mobile phones to incorporate more functions and to reduce their dimensions. This material is also important in future mid-IR devices for sensing and optical communications. We also plan to make and examine the properties of SrBi2Ta209 and La doped Bi4Ti3012 ferroelectric films for memory applications.A major obstacle to taking full advantage of the promising properties of these and other ferroelectric thin films is the conflict between: (a) the need to heat the as-deposited precursors at moderately high temperatures ( 500-700 C) in order to crystallize the coatings and realize the desired electrical properties; and (b) the device engineer's desire to use much lower processing temperatures to enable integration with semiconductor, metal and/ or polymer micro-components. For improved compatibility with device manufacturing methods, and the possibility of integrating thin films with othercomponents on semiconductor wafers, or other temperature-sensitive substrate materials, it is essential that new processing methods are developed which can produce ferroelctric films having device-specification properties without causing damage to the rest of the circuit.We are proposing to study the key materials science and device engineering issues of a new and adventurous approach to film fabrication which offers a breakthrough in the integration of non-Pb materials into microelectronic systems. Initially films of a few microns in thickness will be fabricated, but in the longer term we aim to proceed to make sub-micron films.The new method uses short (nanosecond) pulses of laser radiation directed through a growth substrate to break the bond between film and substrate. This allows the film to be removed and then transferred to an appropriate device substrate. The substrate material used for the growth stage will be MgO and/or sapphire, chosen (a) because of their chemical stability at the temperatures necessary to produce high quality crystalline ferroelectric coatings and (b) for their transparency to laser radiation. As part of the transfer process, the films will be temporarily bonded to a 3` substrate to facilitate the making of electrical contacts and bonding to the end-use device.Because the receptor substrate will not experience any heating, the new technology will be suitable for polymer, metal and semiconductor substrates carrying embedded circuitry.If successful, this project will lead to major gains in microsystem device fabrication as there will no longer be a need to heat the device substrate on which the film is bonded. Device integration will therefore be more straightforward using this new methodolgy.Section 1-3 Date Printe
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