VIPER: Versatile Imager Platform with Enhanced Radiation hardness

Alphacore will develop the capability to provide critical elements for very large space based imagers. These imagers will have sensitivity to UV, visible and NIR wavelengths. The proposed large-format, high-resolution focal plane arrays will meet the following specifications: 8k x 8k pixels Four-sides buttable  (three-sides is the minimum requirement) Pixel size: <~7 µm  (goal is 5 um) Read noise: ~1 e- rms Dark signal ~1x10-4 e-/pixel/sec Operating temperature >150 K Radiation hard The 4-sides buttable readout integrated circuit (ROIC) will be designed in a specific 65nm CMOS Image Sensor (CIS) fabrication process. This process provides photodiode options with enhanced UV and NIR sensitivity. It also provides stitching for fabrication of sensors that are larger than the reticle size (typically 25mm x 25mm) and advanced wafer stacking which allows practically 100% fill factor at small pixel area and 4-side buttable designs. 4-sides buttable FPAs and ROICs provide much higher level of flexibility in construction very large imagers, than 3-sides or 2-sides buttable devices. This provides great benefit to NASA’s future missions. The ROIC will be the bottom layer in this stacked die FPA solution. The ROIC will be designed to be as versatile as possible so that different detector arrays can be bonded to it. The FPA will be implemented as radiation-hardened. Alphacore has extensive experience as a supplier of radiation hard electronics, as well as a radiation test services, to numerous customers. In the image sensor area, we have provided hardened solutions to extreme radiation environments in nuclear applications. Space and strategic radiation environments has been our other focus. Note that image sensor radiation hardening requires specific techniques for hardening the photodiodes and the pixel circuitry and these techniques are relatively unknown as compared to radiation hardening by design (RHBD) techniques for other types of CMOS ICs.