Disruptive Technologies for Electron Bombarded Active Pixel Sensors
Lead Research Organisation:
University of Leicester
Department Name: Physics and Astronomy
Abstract
A variety of sensor types have been operated in electron bombarded mode, including CCDs CMOS sensors, and silicon sensors (pixellated photodiodes) in conjunction with active pixel sensors (e.g. Medipix [2]). This project aims to develop a photon counting capability for the TDCpix [3], a newly developed pixel sensor with exceptional timing resolution. It follows on from a previous PIPSS and BBSRC-funded collaboration with CERN to develop a multi-channel photon-counting detectors with picosecond event timing for life science applications. Our original IPS project utilized a microchannel plate detector with CERN-developed preamplifier and time-to-digital ASICs. The recent development of the TDCpix active pixel sensor by the same group at CERN offers comparable time resolution (100 ps binning, and electronic resolution ~30ps) but with a much higher pixel count (40 x 45 pixel2, 12 x 13.5 mm2), a much higher level of miniaturization provided by integration of the entire electronics on to the chip, and a greatly increased overall count rate capability of ~130 Mcount/s per ASIC, an order of magnitude higher per unit area than its microchannel plate based predecessor.
An electron bombarded TDCpix would offer unrivalled performance with commercial potential for applications using time-correlated single photon counting (TCSPC) such as high content cell screening and other expanding fields in the life science sector, LIDAR instruments for remote sensing, and a variety of other event timing applications where only small arrays of individual photomultiplier tubes are the norm.
Our aim in this project is to identify and develop a technology for photon counting detectors using electron bombarded silicon devices, in order to remove the active pixel sensor from within the vacuum tube, thus greatly simplifying design, de-risking the manufacturing process, and enhancing performance. Removing the chip from the tube will eliminate undesirable elements such as high density vacuum electrical feedthroughs, materials with poor vacuum compatibility, and internal bump, wire, and chip bonding, and will lift the restrictions imposed by these on tube processing which impact manufacturing yield, device reliability, and ultimately, sensor lifetime. Given a successful outcome to this project, we intend to propose a follow-on IPS project, one of whose goals would be to incorporate an additional, relatively low (x20) gain stage using a linear mode electron avalanche process within each pixel of the silicon sensor, matched to the requirements of electron bombarded operation. This will allow the electron bombardment gain to be lowered, reducing the tube operating voltage to safer levels, and reducing the lifetime-threatening radiation damage.
The other elements of an electron bombarded detector design, the vacuum tube including photocathode, and the silicon sensor, will be provided by our industrial collaborators; Photek Ltd., and Micron Semiconductor Ltd, respectively. Photek have extensive experience of design and manufacture of custom vacuum-based detectors with specific expertise in the electron bombarded mode devices, having manufactured an electron bombarded Medipix-based detector. Micron Semiconductor have substantial experience and heritage producing large quantities of custom pixellated silicon sensors for harsh radiation environments at CERN LHC and other similar experiments. Specifically for this project, they have developed a thin entrance window technology which is highly desirable for electron bombarded mode to minimize photoelectron energy loss. The thickness of their currently available Type-9.5 window is 500 Angstroms, and a Type-10 window is under development with a thickness goal of 200 Angstroms. Micron also have a bump-bonding capability necessary for the interconnect development.
An electron bombarded TDCpix would offer unrivalled performance with commercial potential for applications using time-correlated single photon counting (TCSPC) such as high content cell screening and other expanding fields in the life science sector, LIDAR instruments for remote sensing, and a variety of other event timing applications where only small arrays of individual photomultiplier tubes are the norm.
Our aim in this project is to identify and develop a technology for photon counting detectors using electron bombarded silicon devices, in order to remove the active pixel sensor from within the vacuum tube, thus greatly simplifying design, de-risking the manufacturing process, and enhancing performance. Removing the chip from the tube will eliminate undesirable elements such as high density vacuum electrical feedthroughs, materials with poor vacuum compatibility, and internal bump, wire, and chip bonding, and will lift the restrictions imposed by these on tube processing which impact manufacturing yield, device reliability, and ultimately, sensor lifetime. Given a successful outcome to this project, we intend to propose a follow-on IPS project, one of whose goals would be to incorporate an additional, relatively low (x20) gain stage using a linear mode electron avalanche process within each pixel of the silicon sensor, matched to the requirements of electron bombarded operation. This will allow the electron bombardment gain to be lowered, reducing the tube operating voltage to safer levels, and reducing the lifetime-threatening radiation damage.
The other elements of an electron bombarded detector design, the vacuum tube including photocathode, and the silicon sensor, will be provided by our industrial collaborators; Photek Ltd., and Micron Semiconductor Ltd, respectively. Photek have extensive experience of design and manufacture of custom vacuum-based detectors with specific expertise in the electron bombarded mode devices, having manufactured an electron bombarded Medipix-based detector. Micron Semiconductor have substantial experience and heritage producing large quantities of custom pixellated silicon sensors for harsh radiation environments at CERN LHC and other similar experiments. Specifically for this project, they have developed a thin entrance window technology which is highly desirable for electron bombarded mode to minimize photoelectron energy loss. The thickness of their currently available Type-9.5 window is 500 Angstroms, and a Type-10 window is under development with a thickness goal of 200 Angstroms. Micron also have a bump-bonding capability necessary for the interconnect development.
People |
ORCID iD |
| Jonathan Lapington (Principal Investigator) |
| Description | Though the project has officially finished, setbacks and delays in procuring essential hardware items by our CERN collaborator and Micron Semiconductors has meant that the project is still ongoing, having found sufficient in-house funds. In 2016 2 major milestones were accomplished: the successful vacuum sealing of a silicon sensor to a vacuum tube with photocathode, and assembly of the 3D interconnect to mate the active pixel sensor with the silicon device. The pixellated silicon sensor has at last been manufactured by Micron Semiconductors and was delivered in January 2018. We anticipate final tests we be undertaken in 2018/19 and expect that this will result in one or more publications. |
| Exploitation Route | An EB-TDCpix will offer unrivalled performance for applications using time-correlated single photon counting (TCSPC) such as high content cell screening and other expanding fields in the life science sector, LIDAR instruments for remote sensing, and a variety of other event timing applications where only small arrays of individual photomultiplier tubes are the norm. The development of such new technologies will have many beneficiaries including scientific researchers and commercial end-user in the following fields: 1. The life science sector: this technology could have high relevance to high content cell screening for applications such as cell analysis and imaging, toxicology and drug screening, flow cytometry, confocal microscopy, fluorescence microscopy, clinical trials, healthcare R&D. 2. Hygiene and food science: Its application to toxicology could have impact in the hygiene and food industries. 3. Earth remote sensing and environmental science: as a detector to enhance LIDAR techniques used for remote sensing and environmental monitoring applications 4. Particle and nuclear physics: as high time resolution photon counting detectors for scintillators e.g. Cherenkov detectors 5. Gamma Ray Astronomy: a detector for ground-based applications such as the Cherenkov telescope array, etc. 6. Chemistry: applications such as molecular imaging, 3d detection of molecular fragments in laser dissociation experiments, etc. 7. Materials science: applications such as field ion microscopy and other surface analysis techniques where combined imaging with time-of-flight information is required. 8. Medical imaging research: this technology has application to time-of-flight PET, now being actively pursued commercially and expected to develop into a sizeable market, once a high volume, low cost manufacturing solution has matured. This project will also enhance the spin-out of STFC funded technology into other fields, enhancing cross-discipline collaborations between STFC and other sectors, and open pathways to further exploitation of STFC funded technologies. |
| Sectors | Aerospace Defence and Marine Electronics Environment Healthcare Manufacturing including Industrial Biotechology Pharmaceuticals and Medical Biotechnology Security and Diplomacy Other |
| Description | Electron bombarded (EB) mode operation can confer single photon counting sensitivity to the expanding range of active pixel sensors becoming available, which offer ever larger pixel formats and improved timing characteristics. An EB sensor is a hybrid combination of vacuum photodiode tube with solid state sensor. This project aims to provide proof-of-concept level technology solutions to overcome the practical and operational constraints which have thus far limited the success and commercial uptake of this technology. Our overall programme has two major goals: firstly to simplify device manufacture and improve reliability and performance by removing the pixel chip from the vacuum vessel, and secondly, to improve operational characteristics and device lifetime by adding an avalanche gain process within the silicon sensor (SS). Within this Mini-IPS proposal we will demonstrate proof-of-concept for the higher risk key elements of our first goal, de-risking the manufacturing technology in preparation for a follow-on project in which we will address our second goal, the addition of avalanche gain, culminating in demonstration of a full commercial prototype using a ground-breaking pixel chip developed at CERN, the TDCpix, a pixel chip with 100 ps event timing capability and 40 x 45 pixel sq. format. Significant future impact is anticipated. Though the project has officially finished, major setbacks and delays in procuring an essential hardware item by our CERN collaborator have meant that the project is still ongoing, having found sufficient in-house funds. In 2016 2 major milestones were accomplished: the successful vacuum sealing of a silicon sensor to a vacuum tube with photocathode, and assembly of the 3D interconnect to mate the active pixel sensor with the silicon device. The pixellated silicon sensor was manufactured and finally delivered to Leicester by Micron Semiconductors in January 2018. This has enabled us (Leceister and Photek) begin manufacture (Marchg 2018) of a sealed tube with an integral pixellated silicon photodiode readout. We wil then undertake preliminary tube testing in elecrton bombarded mode prior to integration with the TDCpix chip and testing at CENR, anticipated in Q2/Q3 2018. Testing with the vacuum tube and TDCpix in 2018 will lead to one or more publications in 2018/19. |
| First Year Of Impact | 2012 |
| Sector | Manufacturing, including Industrial Biotechology |
| Impact Types | Societal Economic |
| Description | Disruptive Technologies for electron bombarded active pixel sensors |
| Organisation | European Organization for Nuclear Research (CERN) |
| Country | Switzerland |
| Sector | Academic/University |
| PI Contribution | Initial concept, overall project management, system integration and testing |
| Collaborator Contribution | CERN: Design and manufacturing of a high time resolution ASIC for the readout of the active pixel sensor. Photek: Manufacturing of demonstrator prototype devices Micron Semiconductors: Design and manufacture of pixelated silicon sensors and manufacturing test devices |
| Impact | The project is in an early stage |
| Start Year | 2013 |
| Description | Disruptive Technologies for electron bombarded active pixel sensors |
| Organisation | Micron Semiconductor |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Initial concept, overall project management, system integration and testing |
| Collaborator Contribution | CERN: Design and manufacturing of a high time resolution ASIC for the readout of the active pixel sensor. Photek: Manufacturing of demonstrator prototype devices Micron Semiconductors: Design and manufacture of pixelated silicon sensors and manufacturing test devices |
| Impact | The project is in an early stage |
| Start Year | 2013 |
| Description | Disruptive Technologies for electron bombarded active pixel sensors |
| Organisation | Photek Ltd. |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Initial concept, overall project management, system integration and testing |
| Collaborator Contribution | CERN: Design and manufacturing of a high time resolution ASIC for the readout of the active pixel sensor. Photek: Manufacturing of demonstrator prototype devices Micron Semiconductors: Design and manufacture of pixelated silicon sensors and manufacturing test devices |
| Impact | The project is in an early stage |
| Start Year | 2013 |