Fabrication and measurement result of silicon strip sensors

A silicon sensor is very attractive material for medical imaging due to its intrinsic high resolution and fast readout. Silicon sensors of various types were fabricated on a 380 μm-thick n-type, float zone, 5 in. wafer which has high resistivity, 〈100〉 orientation, and is double-sided polished. We manufactured not only DC- and AC-coupled strip sensors but also pixel sensors and RC chips. The RC chips were fabricated for the purpose of using signal readout of the DC-coupled strip sensors. Electrical characteristics of the fabricated silicon sensors, leakage current and capacitance as a function of reverse bias voltage, were measured. Coupling capacitors and biasing resistors in the AC-coupled strip sensors were made by separating implantation from metallization strips with a thin oxide layer and made of polysilicons, respectively. The capacitance and resistance of each channel in the AC-coupled sensor were measured and compared with target values. The signal-to-noise ratio of the fabricated large pixel sensor was also measured by using a ⁹⁰Sr radioactive source.