Transcript Slide 1

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