Radiation Tolerance of Cold 65 nm Process Pixel Readout Electronics to MeV Gammas

Undergraduate Honors Thesis

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/b5644t243

Abstract

Radiation can affect electronics in a number of ways and alter their behavior. The inner tracker of the CMS experiment has sensors and readout chips near the beam line. With the High-Luminosity Large Hydron collider, the dose rate for these electronics will increase, and so will the risk of failure. In order to ensure these electronics can last years near the beam, we must test them with ionizing particles. Experiments have been conducted using X-ray beams, but our irradiation looked for effects of approximately 1 MeV gamma radiation on the readout chips. As the readout chips will be within a meter of the beamline, they will likely see particles of higher energy than X-rays, and it is essential to research how these particles affect the electronics over the course of irradiation up to 1 GRad. We saw some stark differences between the X-ray groups results and our own results. The voltages on the card seem to change less for the gamma-ray irradiation than for the X-ray irradiation, seeming like our chip is acquiring less damage. However, there was more damage to the connection between the aluminum wire bonds and the electroless nickel immersion gold wire bond pads on the SCC. These results show that the chip may be damaged less by gamma rays than by X-rays, except for the wire bonds, for which our irradiation seems to have caused a reaction that damages the wire bonds.

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