KEYWORDS: Sensors, Temperature metrology, Silicon, Chalcogenides, Lenses, Aberration correction, Diodes, Camera shutters, Body temperature, Calibration
We evaluated the possibility of performing temperature measurements using an uncooled infrared focal plane array (IRFPA), consisting of an 8032 array of p-n junction diodes fabricated on a silicon-on-insulator (SOI) substrate (MIR8032B1). We previously reported the sensor design and data collection method for the MIR8032B1 at SPIE in 2021. In this presentation, we describe an aberration correction method and a comparison of different lenses with a high modulation transfer function. We verified the accuracy of the measurements using a shutterless method based on the thermal characteristics of the SOI diodes. Based on the results obtained in the present study, we discuss the applicability of such IRFPAs for temperature measurements.
We describe uncooled infrared focal plane arrays (IRFPAs), which consist of pn junction diodes fabricated on a silicon-on-insulator (SOI) layer using a complementary metal oxide semiconductor (CMOS) process. Based on this technique, we released the Mitsubishi Electric Diode Infrared sensor (MelDIR) into the thermal detector market in 2019. This sensor is an 80×32 IRFPA with a 25 μm pixel pitch, utilizing a chip-scale vacuum-packaging process. To reduce the sensor cost, we developed a common differential circuit that switches the column pixel line, and achieved a significant reduction in chip area. In order to use a low-cost lens in the sensor module, we also developed an aberration correction method that improves the temperature measurement accuracy. Furthermore, we evaluated the effectiveness of a shutter-less method based simply on the thermal behavior of the SOI diode. These techniques allow enhanced performance of the MelDIR.
We developed silicon-on-insulator (SOI) diode-based uncooled infrared focal plane arrays (IRFPAs), in which single-crystal pn junction diodes formed in an SOI layer are used as temperature sensors. These diodes, based on silicon large-scale integration technology, offer excellent uniformity, and have led to the use of high-performance uncooled IRFPAs in a wide variety of applications. In order to extend the pitch to less than 12 μm, a scalable new pixel structure has been developed to reduce the pixel size, based on a novel thermally isolated structure, which is fabricated above a CMOS processed wafer. The pn junction diodes used as a temperature sensor are separated from the underlying substrate by supporting legs made from thin metal wire, forming a cavity. To reduce the pixel size, we are developing a new diode structure by optimizing the ion implantation condition, thinning the SOI layer, and redesigning the supporting legs, achieving a smaller pixel size even with ten serially connected diodes. We also evaluated a new readout circuit architecture that enables an increase in sensitivity by generating a larger change in the diode forward voltage at a given temperature with no change in the number of diodes in the SOI layer. The effectiveness of the proposed readout circuit architecture was verified using a fabricated test element. The sensitivity of the test element was 128% of that for existing circuit structures, and further increases are expected with circuit structure optimization. These techniques have greatly enhanced the performance of our SOI diode based uncooled IRFPAs.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.