A High Frame Rate Hybrid X-Ray Image Sensor

Abstract

This paper describes a solid-state image sensor for high-speed X-ray imaging. The sensor is made up of a light sensitive detector layer bump-bonded to a readout integrated circuit (ROIC). The detector layer is high resistivity n-type silicon and is fully depleted in operation. The p-implanted islands are used to define pixel regions with 100-µm × 100-µm area. The detector layer contains 852 × 209 pixels indium bump-bonded to four identical CMOS ROICs. Each ROIC contains 213 × 209 pixels and is fabricated using a 0.25-µm CMOS process. The ROIC utilizes a capacitive transimpedance amplifier-type front-end coupled to a switched capacitor analog memory. This architecture allows storage of eight frames for high-speed burst imaging of up to a million frames per second, followed by a slower multiplexed readout. Details of the sensor design and operation are presented together with characterization results.Index Terms-High-speed image sensor, hybrid image sensor, X-ray sensor, ROIC, CMOS.

Dimension dependent immunity of X-ray irradiation on low-temperature polycrystalline-silicon TFTs

“…X-ray image sensors are used as radiographs in bone densitometry, for diagnostic purposes in computed tomography, in fluoroscopy to obtain real-time moving images, and in areas of material monitoring that use X-rays for nondestructive testing. [1][2][3] There has been significant academic coverage of X-ray photodetectors, with notable work by Ercan et al, 4) Lim and coworkers, 5) and Bae and coworkers. 6) A review of the existing literature seems to indicate a general consensus that the single crystal silicon provides superior photosensitivity.…”