Functional and performance evaluation of low-resistance strip sensors for beam-loss event protection

A new technological solution to improve the beam-loss protection of silicon strip sensors used in large High Energy Physics experiments is presented. In the current ATLAS-SCT, sensors have Punch-Through protection (PTP) structures included to develop low impedance from the strip to the bias ring in case large voltages exceed some threshold that could damage the strip coupling capacitance. Previous studies show that the high strip resistance limits the beneficial effect of full PTP structures to the area near the structures. In our approach, we extend the PTP protection to the full active area of the sensor by lowering the strip resistance. This is achieved by the addition of a conductive layer connected along the whole strip implant. Strip sensors with different PTP structures, varying the p-stop strip isolation width and the distance between the strip to the bias ring, have been designed and fabricated using our technology proposal, together with standard sensors. Electrical characterization include general performance sensor tests (IV, CV, Rinterstrip, Cinterstrip, Ccoupling) and pulse formation tests to show that sensor performance is not compromised due to the technological modification. Besides, Punch-through DC static measurements and laser-based performance studies have been done to demonstrate the effectiveness of our proposal.