FERROELECTRIC THIN-FILMS FOR INTEGRATED SENSOR AND MEMORY DEVICES

The integration of ferroelectric thin films with existing silicon proc ess technology, and with the rapidly developing area of silicon microm achining, would result in a new generation of memory and sensor device s. Ferroelectric materials have a unique range of properties such as p olarization switching, high dielectric constant pyroelectricity, piezo electricity and electro-optic effects. As a consequence, applications for thin-film devices ave diverse and include non-volatile semiconduct or memories, dynamic random access memories, thin-film capacitors, sur face acoustic wave devices, micro-actuators, pyroelectric and piezoele ctric sensors, optical waveguides, spatial light modulators and freque ncy doublers for integrated lasers. There is intensive activity world- wide in the realization of these various devices. At GEC-Marconi Mater ials Technology, Caswell, attention has focused on integrated films fo r pyroelectric detector arrays for long wavelength infra-red (LWIR) im agers, and non-volatile semiconductor memories. This paper reviews the development, current status and future prospects ferroelectric thin-f ilm fabrication techniques and discusses silicon processing and microm achining compatibility issues. In particular the use of sol-gel and du al ion beam sputtering for the deposition of films of lead zirconate t itanate (PZT) and lead lanthanum titanate (PLT) is described.