Silicon sensors for the Ba Bar vertex tracker: design, electrical tests and production quality control

The paper reports on design, fabrication and test of the double-sided strip detectors (DSSD) for the BaBar vertex tracker. The total number of required sensors is 340, subdivided into 6 different shapes (5 rectangular and one trapezoidal). The strip design is a standard one, with polysilicon bias resistors and integrated decoupling capacitors on both sides. On the n-side the n+ implants, perpendicular to the p+ strips on the p-side, are insulated by individual p-stops. The authors have minimized the insensitive region at the edge of the detectors, so that the cut line is only 700 μm from the axis of the first strip. Special care was put in the design of the trapezoidal detector, in order to make the testing of production of this special sensor as easy as for the rectangular ones. The design and the controls have been optimized to reach the goal value of an average efficiency of 99% for the readout channels, taking into account not only broken capacitors, but also other faulty strips. The paper presents the results of electrical tests on about 200 detectors, belonging to all six different shapes, on capacitance, bias resistance, leakage current and capacitor yield. All results are compatible with the specifications required for the BaBar experiment