Electrical and TCT characterization of edgeless Si detectors diced with different methods

Abstract

High-resistivity p/sup +//n/n/sup +/ Si pad detectors (0.25 cm/sup 2/) were diced, using different dicing tools and methods, into a shape having on one edge no dead space (edgeless detectors). The dicing was extended into the sensitive area of the front p/sup +/ implant. Two different dicing tools were used: laser cutting and scribing. Dicing methods included cutting from the front p/sup +/ side and from the back n/sup +/ side. It was found that, with no chemical or aging treatment of edges cut in this way, all the detectors (diced with different tools and methods) suffered from a very high leakage current of hundreds of /spl mu/A's to mA at full depletion voltage (V/sub fd/), as compared with a few nA before dicing, when measured the same day after dicing. All such detectors showed breakdown just at or near V/sub fd//spl sim/80-100 V. However, after one day of room temperature aging in air, the leakage currents at V/sub fd/ improved dramatically to 1-2 /spl mu/A if diced (laser cutting and scribing) from the backside. Also there was no breakdown up to 500 V. There was little improvement over time if the sensor was diced from the front side. After at least one day of aging, detectors diced from the backside showed normal C-V and charge collection behavior. Nevertheless, the remaining leakage seems to be dominated by surface current and shows little improvement at temperatures down to 130 K. Chemical treatment, though, is promising for further reduction of the surface current <1/spl mu/A at V/sub fd/ and <10 /spl mu/A at 500 V.