Microlens for uncooled infrared array sensor

The paper describes the design and fabrication of a microlens for improvement of the sensitivity of uncooled infrared array sensors. We improved the sensitivity by focusing infrared rays on the detector. The microlens is made of silicon, which is a typical substrate for MEMS technology. We fabricated it by photolithography technology using a gray scale mask and an etch‐back process by selectivity‐controlled dry etching. This process enables us to fabricate a 43‐µm‐high silicon microlens from only a 2‐ to 3‐µm‐high photoresist structure. To confirm the usefulness of the microlens, we developed a small infrared array sensor with microlens. Evaluation results show that the microlens improved the sensitivity by 4.2 times, thereby suggesting that microlens is a promising technology for sensitivity improvement. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(2): 1–8, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11453