Design and Study of A Novel Process for Infrared Microbolometer on (111)-Oriented Single Crystal Silicon Wafer

• Main Authors: Shang-Hung Shen, 沈尚宏
• Other Authors: Chung-Nan Chen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/19892669124120412833

碩士 === 國立高雄應用科技大學 === 光電與通訊研究所 === 96 === This study mainly focuses on infrared bolometer process and design. We propose a novel process for fabricating microbolometers by using anisotropic etching and advanced side-wall protection technique on (111)-oriented silicon wafers. Single crystalline silicon is used as a main supporting layer and sensing material due to its excellent mechanical property, lower 1/f noise and higher temperature coefficient of resistance. For the reason of process compatibility, we utilize an annealed PECVD and TEOS oxide film to protect the side-walls of silicon during anisotropic etching. We found the passivation film can get a lower etch rate in TMAH, dual doped TMAH etchant and ICP, RIE process, after annealing process which can avoid effectively from side wall etching. To explain the reasons of lowering the etch rate of annealed oxide, the observation and measurement of thickness shrinkage and the change of refraction index are done. All silicon anisotropic etching solution, including undoped TMAH, will attack the overlaying Al metal interconnection during the etching process. The addition of silicic acid along with AP (ammonium peroxodisulphate) has been found to prevent Al from etching. In our works, we complete successfully the suspended structure of single crystal silicon with low thermal conductance and low stress. Floating membranes with thin and long leads can be achieved.