Optimization of Low-Resistance Strip Sensors Process and Studies of Radiation Resistance

A further development of a new technological solution to improve the beam-loss protection of silicon strip sensors used in large High Energy Physics experiments is presented. Previous studies show that the high strip resistance limits the beneficial effect of full Punch-Through protection (PTP) structures to the area near the structures. In our approach, we extended the PTP protection to the full active area of the sensor by lowering the strip resistance. This is achieved by the addition of a low-resistivity layer connected along the whole strip implant. We have previously demonstrated that such sensors performed as expected, and that other sensor performance factors arc not compromised due to the technological modification. The current studies are focused on two aspects of practical application: manufacturahility of the sensors with high yield, and their radiation tolerance. To that extend we have made devices with alternative methods of making low-resistivity layers that with better technological performance, and we have irradiated them with protons in the range expected for upgraded ATLAS strips system. The results show that the sensors fabricated with these alternative technological methods remain within specs and that the strip resistance is properly reduced. On the other hand, radiation does not affect the reduced strip resistance.