Description and Evaluation of Multi-Geometry Silicon Prototype Sensors for the LHCb Inner Tracker

Hamamatsu delivered 15 prototype sensors, in February 2002. A summary of the sensor technology specifications and the wafer characteristics is given in table 1. The single-sided and AC coupled sensors were produced from 6” wafers, have a physical dimension of 110 mm×78 mm and a thickness of 320μm of the n-type substrate. The overall dimensions and the technology are identical to the foreseen final sensor design as described in [1]. The sensors consist of five different regions. Two different pitches of p+ strips, 198μm and 237.5μm respectively, are implemented on the sensor. Additionally, the width of the p+ strips is varied. The 198μm region has implant widths of 50μm, 60μm and 70μm, whereas the width of the strips in the 237.5μm region is 70μm and 85μm, respectively. This design results in five different values (two almost are the same) of the ratio strip width to strip pitch, w/p, which is the scaling parameter of the sensor capacitance. The width of the aluminium strip is 8μm wider than the implant width in order to ensure a stable HV-operation of the sensors after irradiation, as it was advocated in reference [2]. Table 2 summarizes the geometries of the prototype sensors.