This paper discusses the potential thermal imaging performance achievable from thermal detector arrays and concludes that the current generation of thin-film ferroelectric and resistance bolometer based detector arrays are limited by the detector materials used. It is proposed that the next generation of large uncooled focal plane arrays will need to look towards higher performance detector materials - particularly if they aim to approach the fundamental performance limits and compete with cooled photon detector arrays. Two examples of bolometer thin-film materials are described that achieve high performance from operating around phase transitions. The material Lead Scandium Tantalate (PST) has a paraelectric-to-ferroelectric phase transition around room temperature and is used with an applied field in the dielectric bolometer mode for thermal imaging. PST films grown by sputtering and liquid-source CVD have shown merit figures for thermal imaging a factor of 2 to 3 times higher than PZT-based pyroelectric thin films. The material Lanthanum Calcium Manganite (LCMO) has a paramagnetic to ferromagnetic phase transition around -20<sup>o</sup>C. This paper describes recent measurements of TCR and 1/f noise in pulsed laser-deposited LCMO films on Neodymium Gallate substrates. These results show that LCMO not only has high TCR's - up to 30%/K - but also low 1/f excess noise, with bolometer merit figures at least an order of magnitude higher than Vanadium Oxide, making it ideal for the next generation of microbolometer arrays. These high performance properties come at the expense of processing complexities and novel device designs will need to be introduced to realize the potential of these materials in the next generation of thermal detectors.
The use of interrupt develop has been reported to enhance the contrast and resolution of novolak resist systems for e-beam lithography. Experience with interrupt develop has demonstrated the ability to control sensitivity and contrast independent from the exposure dose. High contrast and flexible sensitivity are primarily due to the interaction of induction effects of the novolak resist and the length of the develop step. The induction effect is primarily dependent on absorbed energy in the resist. Understanding the distribution of absorbed energy in the resist allows use of the induction effect to control resist profile and image size. A sidewall passivation phenomena results from interrupting the develop process. The passivation enhances the directionality of develop, yielding additional resist profile control. Three diazonapthoquinone novolak resists have been implemented for the fabrication of x-ray masks. During implementation of the resists, the molecular weight of the base resin was found to have a major influence on contrast and image quality. The results show the resolution and image size control achieved using systematic interrupt develop processing.