CMOS image sensors traditionally have used a pinned photodiode with a transfer gate to achieve low dark signal and noise. One drawback of the pinned photodiode is the inability to achieve good Modulation Transfer Function (MTF) as the sensor thickness is increased beyond epitaxial thicknesses greater than 10μm as required for higher red response. This is due to the pinned photodiode providing only a very small voltage to deplete the silicon, which results in significant lateral charge diffusion and poor resolution. The limitation in device thickness means that the QE at longer wavelengths (>600nm) is limited for conventional CMOS pixel technologies. A way to increase the depletion depth is to apply a back bias from the rear of the device, however if one were to do this on standard CMOS image sensors then there would be significant leakage current between the back bias and components on the device causing it to not function. A new patented DDE (Deep Depletion Extension) implant helps diode depletion regions to merge laterally creating a “pinch-off” and prevent leakage from in-pixel transistors. This enables epitaxial thickness of up to 50μm to be fully depleted with negligible leakage. The CIS220 is a new ESA GSTP funded derivative of the CIS120 Capella Space Imager platform which incorporates this patented HiRho back bias structure allowing full depletion of the sensor thickness. This paper will present initial results from back-thinned CIS220 devices with 17μm and 33μm thicknesses and will explore the effect of the back bias on electro-optical test results.

Teledyne e2v has developed the Capella CIS120 which is a general purpose CMOS image sensor with high quantum efficiency that has been specifically designed for space applications and is planned to be used for different Copernicus programs. We will describe the considerations that led to this CMOS sensor concept and then outline the specifications and design details of this back-illuminated detector. Key features include 2048 × 2048 pixels, 10µm pixel pitch, on-chip ADC giving digital outputs in LVDS, both rolling shutter and global shutter modes are available, 45 ke- or 80 ke- full well capacity, peak QE of 90% at 600 nm and latch-up immune and high SEU threshold by design. We will show how the CIS120 can be used for different modes including multi-linear operation, multi-windowing with independent left and right addressing for startracker applications and full frame operation in global or rolling shutter mode for array imaging applications including hyperspectral imaging. The CIS120 is designed to be highly flexible in format allowing; larger variants for astronomical applications and multi die focal plane arrangement, a range of backthinning process options and larger pixel sizes for x-ray applications. Currently the high pixel full capacity version of the CIS120 with 80 ke- per pixel in being characterised. We will present detailed characterisation results and validation data qualifies CIS120 to TRL6 level. We will also present the three different package types have been designed so far for CIS120; standard ceramic package, three side buttable package and sealed Peltier package. Finally, we will summarise plans for future activities including the design and production of a HiRho variant to give significantly improved NIR sensitivity by applying voltage to back surface to be able to operate in full depletion.

Teledyne e2v has designed and prototyped a large-format, high rate sensor with excellent read-noise and high quantum efficiency. The LVSM (or CIS124) sensor development has been funded by the European Southern Observatory for use on their Extremely Large Telescope. The CMOS sensor is anticipated to be valuable for use on other large telescopes for adaptive optics and similar high-rate and low signal applications. We describe the considerations that led to this CMOS sensor concept and then outline the specifications and design details of this back-illuminated, Peltier-cooled sensor. Key features include800x800 pixels, at least 700 frames/second, digital implementation, 9 or 10 bits, plus four analogue gains programmable by region, peak QE of 90% at 700 nm, less than 3 eread-noise, programmable rolling shutter to allow S-H and pyramid WFS. The sealed package includes Peltiercooling and mounting features for incorporation into a wavefront sensor camera. We report on front-illuminated tests which validate electrically the design and includes electro-optical data.

CCDs have been used for many years for Hyperspectral imaging missions and have been extremely successful. These include the Medium Resolution Imaging Spectrometer (MERIS) [1] on Envisat, the Compact High Resolution Imaging Spectrometer (CHRIS) on Proba and the Ozone Monitoring Instrument operating in the UV spectral region. ESA are also planning a number of further missions that are likely to use CCD technology (Sentinel 3, 4 and 5). However CMOS sensors have a number of advantages which means that they will probably be used for hyperspectral applications in the longer term. There are two main advantages with CMOS sensors: First a hyperspectral image consists of spectral lines with a large difference in intensity; in a frame transfer CCD the faint spectral lines have to be transferred through the part of the imager illuminated by intense lines. This can lead to cross-talk and whilst this problem can be reduced by the use of split frame transfer and faster line rates CMOS sensors do not require a frame transfer and hence inherently will not suffer from this problem. Second, with a CMOS sensor the intense spectral lines can be read multiple times within a frame to give a significant increase in dynamic range. We will describe the design, and initial test of a CMOS sensor for use in hyperspectral applications. This device has been designed to give as high a dynamic range as possible with minimum cross-talk. The sensor has been manufactured on high resistivity epitaxial silicon wafers and is be back-thinned and left relatively thick in order to obtain the maximum quantum efficiency across the entire spectral range

The Jupiter Icy Moon Explorer (JUICE) has been officially adopted as the next Large-class mission by the European Space Agency, with a launch date of 2022. The science payload includes an optical camera, JANUS, which will perform imaging and mapping observations of Jupiter, its moons and icy rings. A 13 slot filter wheel will be used to provide spectral information in order for the JANUS experiment to study the geology and physical properties of Ganymede, Europa and Io, and to investigate processes and structures in the atmosphere of Jupiter.The sensor selected for JANUS is the back-thinned CIS115, a 3 MPixel CMOS Image Sensor from e2v technologies. The CIS115 has a 4-Transistor pixel design with a pinned photodiode to improve signal to noise performance by reducing dark current and allowing for reset level subtraction. The JUICE mission will consist of an 8 year cruise phase followed by a 3 year science phase in the Jovian system. Models of the radiation environment throughout the JUICE mission predict that the End of Life (EOL) non-ionising damage will be equivalent to 10(10) protons cm(-2) (10 MeV) and the EOL ionising dose will be 100 krad(Si), once the shielding from the spacecraft and instrument design is taken into account. An extensive radiation campaign is therefore being carried out to qualify and characterise the CIS115 for JANUS, as well as other space and terrestrial applications.Radiation testing to take the CIS115 to twice the ionising dose and displacement damage levels was completed in 2015 and the change in sensor performance has been characterised. Good sensor performance has been observed following irradiation and a summary of the key results from the campaign using gamma irradiation (ionising dose) will be presented here, including its soft X-ray detection capabilities, flat-band voltage shift and readout noise. In 2016, further radiation campaigns on flight-representative CIS115s will be undertaken and their results will be disseminated in future publications.