Research On 15×15μm~2 Multilayer Microbolomer Structure Design

Micro-bolometer uncooled infrared focal plane arrays(IRFPAs), which exhibits the advantages of low power consumption, high performance and low costs, and gains a promising expectation in military supplies and in civilian use. In recent years, with the development of infrared devices towards large scale and high density, the main specifications of micro-bolometer uncooled infrared focal plane arrays has been developed from the original 320×240 to 640×480,1024×768 and so on. Pixel size has been developed from 65×65 to the current small size of 15×15. The traditional single- layer structure has changed a great deal, such as current double- layer umbrella structure and double- layer S-shaped structure. However, few references on 15μm×15μm micro bolometer model structure s have been reported, and research on three-tier structure of the model is rarely seen both at home and abroad. Consequently, the performance of the smal-sized device is far from clear in academic circle.For the purpose of studying the properties and structure of small-sized micro-bolometer, the dissertation adopts the professional software of Microelectromechanical Systems, Intellisuite. The software is used to construct the Finite Element Analysis(FEA) model of the double-layer S-shaped invisible cantilever micro-bolometer and the FEA model of the three-layer S-shaped invisible cantilever micro-bolometer, which pixel size are 15μm×15μm. We take the noise equivalent temperature difference(N ETD) and therma l response time as the key performance indicators. On the basis, their mechanical, thermal and electrical properties are simulated in this dissertation.Mechanical properties play a vital part in ensuring the stability of micro-bolometer. By adjusting the internal stress of each material layer, the mechanical properties of the three-dimensional model of the two structures is optimized, which results in a smaller deformation. The dissertation proves that its supporting layer and the electrode layer are the primary stress-bearing layers. The optimal design, to some extent, can facilitate the development of micro-bolometer.In addition, through the simulation of thermal and electrical properties on both invisible cantilever, the present paper obtains temperature rising of thermal and the initial resistance value, carries out thermoelectric field-coupling finite element analysis on the two structures, and simulates the actual working state of the device. The noise equivalent temperature difference(NETD) and thermal response time are also obtained, which favorably satisfy the required parameters.Through co MParison and contrast, it is clear that indicators of three- layer S-shaped model are better than those of the double- layer S-shaped model, which plays a vital role in designing the small-sized and multi- layered micro-bolometer. Besides, it has an important significance to accelerate the small size of uncooled infrared focal plane array detectors and high performance of the structural design.