Silicon Based Uncooled Microbolometer

摘要

During the last decade, uncooled microbolometer infrared detectors have attracted the attention of military and civilian infrared detection and imaging industry due to their significant advantages. In actuality, infrared imaging systems play a critical role in sectors such as thermography (predictive maintenance and building inspection), commercial and civilian applications (vision automotive, surveillance, navigation and fire-fighting), and defense industry (thermal weapon sight, soldier vision and vehicle vision enhancer). Compared with the cryogenically cooled infrared photon detectors, uncooled infrared imaging technology offers advantages such as operation at room temperature, light weight and size, reduced power consumption, easy integration with read-out electronics and broadband response capability.;The motivation for this study is the consideration of silicon as an alternative candidate to replace the standard infrared detector thermosensing materials, as a result of its low cost and easy integration with the actual silicon planar lithography microfabrication techniques. No prior attempts are known in the literature on the use of low doped p-type silicon (p-Si) as a thermosensing material in thermal infrared detectors.;The main aim of this research work is the design, modeling and simulation of low doped p-Si based uncooled microbolometer infrared detector. The theoretical optical modeling, and electronic performance are analyzed and explained. Radiative properties, as function of thin film thickness, of some commonly used thin films of dielectric materials, aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminum nitride (AlN) and silicon nitride (Si3N4) are investigated within the infrared spectral range of 1.5--14.2 microm.;A novel thermally isolated, suspended square-shaped multilayer structure microbolometer is proposed. Its radiative properties are simulated and optimized in the long wavelength spectral range of 8--14 microm (transmission window at room temperature). The performance of the proposed microbolometer structure is numerically calculated by the figures of merit that characterize the thermal detector response. The dimensions of the microbolometer structure are optimized in order to achieve the maximum responsivity and low thermal time response required by the imaging systems, while securing the stability and support of the structure.