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Fabrication of a Photodetector Array on Thin Silicon Wafer Kim Manser (RIT, MicroE Co-Op) Background • A very low noise imaging detector enables future NASA astrophysics and planetary space missions. • RIDL designs and fabricates a focal plane array having many advantages. • Very low noise • Immune to radiation • Low power dissipation • Low noise radiation and pickup • Low mass electronics • More robust electronics Goals • Fabricate a photodetector array on thin silicon wafer and then bond it to CMOS ROIC Plan • The readout integrated circuit (ROIC) has been designed by a team headed by Dr. Zeljko Ignjatovic at the University of Rochester and is being fabricated by an outside facility. • The detector design is currently under fabrication at RIT in the Semiconductor and Microsystems Fabrication Laboratory, a class-100 clean room Device Operation • The device is made up of a detector (collects light and generates charge) and the ROIC (translates the detector signals into image information). • When a photon is incident on the detector, it excites an electron-hole pair, which is freed from the silicon crystal lattice and carried to opposite sides of the device (where the charge is collected in localized areas called pixels). • The ROIC reads the detector output, which is a signal that is proportional to the incoming flux of light. Device Fabrication and Testing ROIC n-Si n+ Si Bonds to ROIC p+ Si Thermal oxide Photodetector LTO Al In Cross-Sectional View ROIC Photodetector Photons