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Design and Fabrication of Vertically-Integrated CMOS Image Sensors
Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB T6G 2V4, Canada
* Author to whom correspondence should be addressed.
Received: 4 February 2011; in revised form: 26 March 2011 / Accepted: 11 April 2011 / Published: 27 April 2011
Abstract: Technologies to fabricate integrated circuits (IC) with 3D structures are an emerging trend in IC design. They are based on vertical stacking of active components to form heterogeneous microsystems. Electronic image sensors will benefit from these technologies because they allow increased pixel-level data processing and device optimization. This paper covers general principles in the design of vertically-integrated (VI) CMOS image sensors that are fabricated by flip-chip bonding. These sensors are composed of a CMOS die and a photodetector die. As a specific example, the paper presents a VI-CMOS image sensor that was designed at the University of Alberta, and fabricated with the help of CMC Microsystems and Micralyne Inc. To realize prototypes, CMOS dies with logarithmic active pixels were prepared in a commercial process, and photodetector dies with metal-semiconductor-metal devices were prepared in a custom process using hydrogenated amorphous silicon. The paper also describes a digital camera that was developed to test the prototype. In this camera, scenes captured by the image sensor are read using an FPGA board, and sent in real time to a PC over USB for data processing and display. Experimental results show that the VI-CMOS prototype has a higher dynamic range and a lower dark limit than conventional electronic image sensors.
Keywords: CMOS image sensors; photodetectors; logarithmic sensors; stacked ICs; flip-chip bonding
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Cite This Article
MDPI and ACS Style
Skorka, O.; Joseph, D. Design and Fabrication of Vertically-Integrated CMOS Image Sensors. Sensors 2011, 11, 4512-4538.
Skorka O, Joseph D. Design and Fabrication of Vertically-Integrated CMOS Image Sensors. Sensors. 2011; 11(5):4512-4538.
Skorka, Orit; Joseph, Dileepan. 2011. "Design and Fabrication of Vertically-Integrated CMOS Image Sensors." Sensors 11, no. 5: 4512-4538.