||Pixel size scaling down of infrared microbolometer will cause reduction in its sensitivity. In this thesis, we investigate the effect of leg geometry on electrical characteristic for the device. Due to the optimal leg design, the infrared microbolometer can reduce its pixel size and maintain an excellent sensitivity simultaneously. We use MEMS processing technology with six masks to produce microbolometer device. The devices’ legs have been defined as normal leg (type A), double leg (type B), and half leg (type C) three different designs by various masks. Different device lengths from 15 um to 50 um are fabricated for each leg design. We choose device length of 30 um, 40 um, 45 um and 50 um to discuss in detail. The electrical resistance and TCR (temperature coefficient of resistance) of 12 different devices are well studied.|
In addition, we inspect key processes by optical microscope (OM) and focused ion beam (FIB) to confirm the accuracy of lithography and etching. Agilent B1500A semiconductor parameter measuring instrument is applied to measure electrical characteristic of the devices. Temperature of the samples is controlled by variable temperature system. Based on the experimental results, the resistances of most devices are several MΩ. Under the same device length, type B design has a maximum resistance. However, type A design has a maximum TCR value, which of most devices are above -2% /oC.
As a result, type A (normal leg) design has the best performance among all designs. It has suitable resistance value, thermal isolation, and higher TCR value. Thus applying the design to pixel size reduction can optimize the sensitivity.