Fabrication of AC-coupled double-sided silicon strip sensor

摘要

Department of Physics, Kyungpook National University, Daegu 702-701, Republic of Korea;Department of Physics, Kyungpook National University, Daegu 702-701, Republic of Korea;Department of Physics, Kyungpook National University, Daegu 702-701, Republic of Korea;Department of Physics, Kyungpook National University, Daegu 702-701, Republic of Korea;Department of Physics, Kyungpook National University, Daegu 702-701, Republic of Korea;Department of Physics, Kyungpook National University, Daegu 702-701, Republic of Korea;%The AC-coupled double-sided silicon microstrip sensors are designed and 14 masks are used to produce prototype strip sensors. The biasing resistors are made of p-doped polysilicons and the coupling capacitors are built by separating implanted strips and readout strips by a thin oxide layer. The p-stops in the atoll patterns are introduced to disrupt an electron accumulation layer at the Si-SiO_2 interface on the ohmic side. The junction side has a double metal structure using two metal layers separated from each other by a thick insulator layer. The strip sensors are fabricated on a 5-in., high resistivity, <100>-orientation, and 380 μm thick n-type double-sided polished silicon wafer. The prototype sensor with an area of 2.8 × 2.8 cm2 consists of 256(512) readout channels with a strip pitch of 100(50)μm. The leakage currents and the bulk capacitances as a function of the reverse bias voltage are measured to understand the fabrication process of the prototype sensors. The signal to noise ratios are measured by using a ~(90) Sr radioactive source in order to evaluate performance of the sensors. The design of the AC-coupled double-sided silicon strip sensor and its various components are described, and measurements of the electric characteristics and the signal to noise ratio are presented.