Advances in monolithic pixel detectors Snoeys, W.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
August 2024, Letnik:
1065
Journal Article
Recenzirano
Odprti dostop
Monolithic sensors, and CMOS sensors in particular, revolutionized visible imaging, and will be widely applied in high energy physics, but with different requirements and implementations than sensors ...for visible light (Snoeys, 2023).
CMOS cameras revolutionized the visible imaging world, and now also move into other fields. After years of intensive research with significant progress and introduction in a few experiments, ...monolithic active pixel sensors integrating sensor matrix and readout in one piece of silicon are considered for wider application in high energy physics. Detailed requirements and implementation of CMOS sensors in high energy physics differ from those for visible light. This paper tries to give an overview.
•Monolithic Active Pixel Sensors (MAPS) will be used widely in High Energy Physics (HEP).•CMOS MAPS for HEP greatly profit from the progress of CMOS imagers for visible light.•Tolerance up to several 1016 1 MeV neq/cm2 and several MGy is within reach.•Design for yield and lower power densities will enable stitching and wafer stacking.•Efficient volume test, assembly, and mounting will enable large area detectors.•Experts in digital-on-top design, verification and TCAD are essential for MAPS in HEP.•Large area pixel sensors are enabling devices for many cutting edge research fields.•MAPS production volume for HEP should allow access to the most advanced technologies.•Our HEP community can have an impact on society through its MAPS development.
Hybrid pixel detectors with readout and sensor in different silicon chips are in overwhelming majority in today’s high energy physics experiments, but monolithic active pixel sensors (MAPS) have ...received significant attention because they offer easier detector assembly, lower cost, and other advantages like lower material and higher granularity. MAPS now move towards commercial CMOS technologies, which offer significant radiation tolerance and substrates compatible with particle detection and combine circuit performance and density with volume production capability at reasonable cost. MAPS in commercial CMOS technologies were used for the first time in the STAR experiment, adopted for the ALICE experiment, and are being considered for the most aggressive applications, like the ATLAS HL-LHC upgrade and future colliders like the FCC and CLIC. Significant improvements are made in every iteration with challenges in sensor and frontend design, architecture, speed, timing, radiation tolerance and system issues. This paper tries to give an overview. Some considerations on digital power consumption versus hit rate and clock distribution over the pixel matrix are added as well.
Monolithic CMOS sensors for high energy physics Snoeys, W.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2019, Letnik:
924
Journal Article
Recenzirano
Monolithic active pixel sensors manufactured in commercial CMOS technologies revolutionized imaging for consumer applications and are now moving into high energy physics: they have been adopted in ...the STAR and the ALICE experiments, and are being considered for the most demanding applications like the upgrade of the ATLAS pixel detector. These devices offer integration of sensor and readout in a single chip and low material budget. Deep submicron commercial CMOS technologies offer high speed and density, leading to high bandwidth capability and good spatial resolution for monolithic sensors, and volume production capability at low cost, important for large systems. This paper tries to give an overview.
Monolithic pixel detectors for high energy physics Snoeys, W.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
731
Journal Article
Recenzirano
Monolithic pixel detectors integrating sensor matrix and readout in one piece of silicon have revolutionized imaging for consumer applications, but despite years of research they have not yet been ...widely adopted for high energy physics. Two major requirements for this application, radiation tolerance and low power consumption, require charge collection by drift for the most extreme radiation levels and an optimization of the collected signal charge over input capacitance ratio (Q/C). It is shown that monolithic detectors can achieve Q/C for low analog power consumption and even carryout the promise to practically eliminate analog power consumption, but combining sufficient Q/C, collection by drift, and integration of readout circuitry within the pixel remains a challenge. An overview is given of different approaches to address this challenge, with possible advantages and disadvantages.
Monolithic pixel detectors integrating sensor matrix and readout in one piece of silicon are only now starting to make their way into high energy physics. Two major requirements are radiation ...tolerance and low power consumption. For the most extreme radiation levels, signal charge has to be collected by drift from a depletion layer onto a designated collection electrode without losing the signal charge elsewhere in the in-pixel circuit. Low power consumption requires an optimization of Q/C, the ratio of the collected signal charge over the input capacitance 1. Some solutions to combine sufficient Q/C and collection by drift require exotic fabrication steps. More conventional solutions up to now require a simple in-pixel readout circuit. Both high voltage CMOS technologies and Monolithic Active Pixel Sensors (MAPS) technologies with high resistivity epitaxial layers offer high voltage diodes. The choice between the two is not fundamental but more a question of how much depletion can be reached and also of availability and cost. This paper tries to give an overview.
For the upgrade of its Inner Tracking System, the ALICE experiment plans to install a new tracker fully constructed with monolithic active pixel sensors implemented in a standard 180 nm CMOS imaging ...sensor process, with a deep pwell allowing full CMOS within the pixel. Reverse substrate bias increases the tolerance to non-ionizing energy loss (NIEL) well beyond 10131MeVneq∕cm2, but does not allow full depletion of the sensitive layer and hence full charge collection by drift, mandatory for more extreme radiation tolerance. This paper describes a process modification to fully deplete the epitaxial layer even with a small charge collection electrode. It uses a low dose blanket deep high energy n-type implant in the pixel array and does not require significant circuit or layout changes so that the same design can be fabricated both in the standard and modified process. When exposed to a 55Fe source at a reverse substrate bias of −6 V, pixels implemented in the standard and the modified process in a low and high dose variant for the deep n-type implant respectively yield a signal of about 115 mV, 110 mV and 90 mV at the output of a follower circuit. Signal rise times heavily affected by the speed of this circuit are 27.8+∕−5 ns, 23.2+∕−4.2 ns, and 22.2+∕−3.7 ns rms, respectively. In a different setup, the single pixel signal from a 90Sr source only degrades by less than 20% for the modified process after a 10151MeVneq∕cm2 irradiation, while the signal rise time only degrades by about 16+∕−2 ns to 19+∕−2.8 ns rms. From sensors implemented in the standard process no useful signal could be extracted after the same exposure. These first results indicate the process modification maintains low sensor capacitance, improves timing performance and increases NIEL tolerance by at least an order of magnitude.
CMOS pixel sensors with a small collection electrode combine the advantages of a small sensor capacitance with the advantages of a fully monolithic design. The small sensor capacitance results in a ...large ratio of signal-to-noise and a low analogue power consumption, while the monolithic design reduces the material budget, cost and production effort. However, the low electric field in the pixel corners of such sensors results in an increased charge collection time, that makes a fully efficient operation after irradiation and a timing resolution in the order of nanoseconds challenging for pixel sizes larger than approximately forty micrometers. This paper presents the development of concepts of CMOS sensors with a small collection electrode to overcome these limitations, using three-dimensional Technology Computer Aided Design simulations. The studied design uses a 0.18 μm process implemented on a high-resistivity epitaxial layer.
The upgrade of the ATLAS 1 tracking detector for the High-Luminosity Large Hadron Collider (LHC) at CERN requires novel radiation hard silicon sensor technologies. Significant effort has been put ...into the development of monolithic CMOS sensors but it has been a challenge to combine a low capacitance of the sensing node with full depletion of the sensitive layer. Low capacitance brings low analog power. Depletion of the sensitive layer causes the signal charge to be collected by drift sufficiently fast to separate hits from consecutive bunch crossings (25 ns at the LHC) and to avoid losing the charge by trapping. This paper focuses on the characterization of charge collection properties and detection efficiency of prototype sensors originally designed in the framework of the ALICE Inner Tracking System (ITS) upgrade 2. The prototypes are fabricated both in the standard TowerJazz 180nm CMOS imager process 3 and in an innovative modification of this process developed in collaboration with the foundry, aimed to fully deplete the sensitive epitaxial layer and enhance the tolerance to non-ionizing energy loss. Sensors fabricated in standard and modified process variants were characterized using radioactive sources, focused X-ray beam and test beams before and after irradiation. Contrary to sensors manufactured in the standard process, sensors from the modified process remain fully functional even after a dose of 1015neq/cm2, which is the the expected NIEL radiation fluence for the outer pixel layers in the future ATLAS Inner Tracker (ITk) 4.
The CLIC Tracker Detector (CLICTD) is a monolithic pixel sensor. It is fabricated in a 180 nm CMOS imaging process, modified with an additional deep low-dose n-type implant to obtain full lateral ...depletion. The sensor features a small collection diode, which is essential for achieving a low input capacitance. The CLICTD sensor was designed as a technology demonstrator in the context of the tracking detector studies for the Compact Linear Collider (CLIC). Its design characteristics are of broad interest beyond CLIC, for HL-LHC tracking detector upgrades. It is produced in two different pixel flavours: one with a continuous deep n-type implant, and one with a segmented n-type implant to ensure fast charge collection. The pixel matrix consists of 16 × 128 detection channels measuring 300μm×30μm. Each detection channel is segmented into eight sub-pixels to reduce the amount of digital circuity while maintaining a small collection electrode pitch. This paper presents the characterisation results of the CLICTD sensor in a particle beam. The different pixel flavours are compared in detail by using the simultaneous time-over-threshold and time-of-arrival measurement functionalities. Most notably, a spatial resolution down to (4.6±0.2)μm is measured. A time resolution down to (5.8±0.1)ns is observed, after applying an offline time-walk correction using the pixel-charge information. The hit detection efficiency is found to be well above 99.7% for thresholds of the order of several hundred electrons.
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