Activating Backside Junctions in Thin Silicon Pixel Detectors through Laser Anneal

SueYeon Chung, Department of Physics, Cornell University, Ithaca, NY 14853 Julia Thom, Department of Physics, Cornell University, Ithaca, NY 14853

Abstract This project is part of a larger effort to develop thinned silicon pixel detectors for particle detection in High Energy Physics experiments. These detector arrays, containing active CMOS pixel circuitry on the top of the wafer, will require formation of an extremely low leakage backside junction at the end of processing. This requires a high dose implant followed by an activation anneal. Due to the already existing circuitry, static temperatures must remain below 450oC during this anneal. Pulsed laser annealing is currently the most promising method for achieving suitable activation of this backside implant. We have focused specifically on understanding and optimizing a process for activating these backside junctions. We have fabricated a range of planar diodes with guard rings on conventional silicon wafers and implanted and laser annealed them with varying parameters. We have studied the diode reverse leakage properties as a function of diode area as well as implant and laser anneal parameters.

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