Design and Implementation of a High Resolution CMOS X-Ray Imager with Amorphous Selenium Sensor
Peter Levine and Karim Karim
This thesis presents a novel system for high resolution X-ray imaging in medical and industrial applications. Complementary metal oxide semiconductor (CMOS) technology is a standard technology used in most state of the art electronic systems including imagers. On the other hand,amorphous selenium (a-Se) is an element that is sensitive to a wide range of X-Ray photon energies and provides electrical current as the output signal.
Increasing the effective spatial resolution is one the primary goals of state of the art imaging systems. The goal of this thesis is to integrate the a-Se sensor and CMOS readout circuit together to make an ultimate high resolution X-ray imager. Other features of the imager like noise performance, dynamic range, imaging speed and fill factor, are competitive with other X-ray imaging systems. All of the signal reading circuitry is implemented on the CMOS chip and the a-Se sensor is deposited on top of the through post processing. This thesis also describe the design of extended hardware and software needed to properly operate the imager.
We demonstrate our imager with a 64×64 prototype colony pixels with 5.6×6.25 (µm)^2 and 11.2×6.25 (µm)^2 areas.Our results include characterization of the electronic and X-ray imaging performance of our system. We also show X-ray images with effective resolution down to 14µm.