Abstract
In order to support the high luminosity upgrades at ATLAS and CMS, thinned silicon sensors for hybrid pixel detectors are critical to improve radiation hardness, reduce detector mass, and address high occupancy rates. Because silicon wafer processing tools are not equipped to handle thin wafers, the thinning step cannot be performed until after the majority of the processing steps are complete, requiring post-processing to create the doped region that constitutes the diode contact at the backside of the wafer. However, the high temperature anneal required to activate the dopant would be damaging to the existing front side structures. A new microwave annealing technology can activate the backside implant at low temperature, without damaging the frontside structures. We employed this technique to post-process 6-inch wafers from two different high energy physics (HEP) sensor foundries. Results are promising, indicating that the microwave anneal backside has potential to become a cost-effective solution for manufacturing thin sensors for large area HEP detectors.
