MIT Lincoln Laboratory
Who it subcontracts to
No subawards reported under its lunar awards.
Who it works for
IN PREVIOUS WORK, MITLL FABRICATED TWO DIFFERENT P-CHANNEL CCDS WITH NON-DESTRUCTIVE READOUT AMPLIFIERS, INTERNALLY DESIGNATED AS CCID101 AND CCID103. THE FORMER UTILIZES SKIPPER AMPLIFIERS DEVELOPED BY DEPARTMENT OF ENERGY INVESTIGATORS (INCLUDING THE PI), WHILE THE LATTER USES AN DIFFERENT AMPLIFIER DUBBED SISERO (SINGLE ELECTRON-SENSITIVE READOUT AMPLIFIER). BOTH AMPLIFIERS HAVE DEMONSTRATED REPETITIVE NONDESTRUCTIVE READOUT (RNDR) CAPABILITY AND DEEP SUB-ELECTRON READ NOISE AFTER MULTIPLE READS, WITH RECENT RESULTS ON SISERO INDICATING A SPEED AND NOISE ADVANTAGE COMPARED TO SKIPPER AMPLIFIERS. WITH THESE LOW NOISE LEVELS, THESE CCDS ARE OUTSTANDING CANDIDATES TO MEET THE NEEDS OF PHOTON-COUNTING SENSORS FOR EXOPLANET SPECTROSCOPY AS REQUIRED BY THE HABITABLE WORLDS OBSERVATORY CONCEPT. CCID101 AND CCID103 WERE CONTAINED IN A SINGLE RETICLE FIELD AND, IN A PREVIOUS PROGRAM, FABRICATED AT MITLL. SIX WAFERS WERE COMPLETELY PROCESSED THROUGH FRONT ILLUMINATION WHILE AN ADDITIONAL EIGHTEEN WAFERS WERE HELD AT AN INTERMEDIATE POINT IN PROCESSING AS RISK MITIGATION. WHILE CCID101 AND CCID103 HAVE DEMONSTRATED EXCELLENT NOISE PERFORMANCE, REALIZED IN THE BATCH OF SIX WAFERS THAT COMPLETED FRONT ILLUMINATION, BACK ILLUMINATION IS REQUIRED TO ACHIEVE HIGH SENSITIVITY TO OPTICAL PHOTONS. IN PARTICULAR, MOLECULAR-BEAM EPITAXY (MBE) IS NEEDED FOR BACK-SURFACE PASSIVATION TO ENABLE HIGH SENSITIVITY TO ULTRAVIOLET PHOTONS WHICH HAVE A SHALLOW ABSORPTION LENGTH. FURTHERMORE, BECAUSE HIGH SENSITIVITY IS REQUIRED IN THE NEAR INFRARED BAND, THESE CCDS MUST BE VERY THICK DUE TO THE LONG ABSORPTION LENGTH OF PHOTONS IN SILICON. CONSEQUENTLY, THESE BACK-ILLUMINATED IMAGE SENSORS WILL NOT BE MOUNTED TO A HANDLE WAFER AND THINNED TO A THICKNESS OF 50-100 ΜM, AS IS COMMON PRACTICE FOR OTHER CCDS, BUT RATHER WILL BE APPROXIMATELY 650 ΜM-THICK FREESTANDING WAFERS. CONSEQUENTLY, THE LIGHT-FACING SURFACE AND BOND PADS ON THESE DEVICES ARE ON OPPOSITE SIDES OF THE WAFER, REQUIRING DEVELOPMENT OF NEW METHODS TO TEST THESE CCDS THAT ENABLE CONTACT TO FRONT SURFACE BOND PADS WITHOUT MARRING THE BACK SURFACE OF THE DEVICE. IN THE PROPOSED WORK, MITLL WILL COMPLETE THE FOLLOWING TASKS: • COMPLETE FRONT ILLUMINATION OF THE EIGHTEEN WAFERS CONTAINING CCID101 AND CCID103 DESCRIBED ABOVE. • DEVELOP PROCESSES TO REALIZE THICK FREESTANDING BACK-ILLUMINATED CCDS WITH MBE BACK-SURFACE PASSIVATION, IN PARTICULAR DEMONSTRATING PROCESSES TO REMOVE BACKSIDE GETTERING LAYERS AND REALIZE HIGH-QUALITY MBE GROWTH ON THE BACK SURFACE. • FABRICATE TWO LOTS OF 3-9 CCD WAFERS THROUGH BACK ILLUMINATION. THE FIRST AND SECOND LOT WILL BE SEPARATED BY TESTING AND ANALYSIS TASKS TO INFORM PROCESS DEVELOPMENT THAT WILL FURTHER IMPROVE SENSOR PERFORMANCE. • DICE INDIVIDUAL CCDS AND SUPPLY THEM TO THE PI FOR PACKAGING. • MODIFY TEST ELECTRONICS TO SUPPORT TESTING OF PACKAGED CCID101 AND CCID103 DEVICES. ATTACHMENT 5A PAGE (2) PROPRIETARY INFORMATION • TEST PACKAGED CCDS AT MITLL, CHARACTERIZING OPERABILITY, COSMETICS, DARK CURRENT, AND QUANTUM EFFICIENCY. • DELIVER THE MOST PROMISING PACKAGED DEVICES TO THE PI FOR FURTHER ANALYSIS. • AFTER PACKAGED DEVICES ARE DELIVERED, PROVIDE SUPPORT FOR THE REMAINDER OF THE PROGRAM; E.G. TO ASSIST IN DEVICE ANALYSIS AND TROUBLESHOOTING.