Effects of dielectrics on the characteristics of large-area silicon microstrip sensors

An 8 × 4 cm² single-sided silicon microstrip sensor with coupling capacitors and polysilicon bias resistors has been fabricated with planar technology. The oxide-nitride-oxide (ONO) films have been chosen to replace the usual SiU₂ layer as the dielectric of the coupling capacitor. In conjunction with a reordering of the process sequence for layer formations, the proposed process could be used to fabricate sensors with self-moisture protection and free from the effect of pinholes. From the measurement results of special p-n junction test structures, we found that their leakage current was dominated by that of the sidewall one. Stress measurement and Sirtl-etch analysis revealed that the sidewall leakage current was increased by the dielectric stress and implantation damage. A boron solid-source predeposition process was employed to reduce this leakage current. From the results of electrical measurement and beam test on sensors, it was shown that the proposed process was able to produce sensors having very good performance.