FLUORESCENT MICROTHERMAL IMAGING - THEORY AND METHODOLOGY FOR ACHIEVING HIGH THERMAL RESOLUTION IMAGES

The fluorescent microthermal imaging technique (FMI) involves coating a sample surface with an inorganic-based thin film that, upon exposure to UV light, emits temperature-dependent fluorescence [1-8]. FMI offe rs the ability to create thermal maps of integrated circuits with a th ermal resolution theoretically limited to 1 m degrees C and a spatial resolution which is diffraction-limited to 0.3 mu m. Even though the f luorescent microthermal imaging (FMI) technique has been around for mo re than a decade, many factors that can significantly affect the therm al image quality have not been systematically studied and characterize d. After a brief review of FMI theory, we will present our recent resu lts demonstrating for the first time three important factors that have a dramatic impact on the thermal quality and sensitivity of FMI. Firs t, the limitations imparted by photon shot noise and improvement in th e signal-to-noise ratio realized through signal averaging will be disc ussed. Second, ultraviolet bleaching, an unavoidable problem with FMI as it currently is performed, will be characterized to identify ways t o minimize its effect. Finally, the impact of film dilution on thermal sensitivity will be discussed.