Influence of radiation and AC coupling on time performance of analog pixels test structures in 65 nm CMOS technology

Monolithic Active Pixel Sensors (MAPS) in advanced CMOS imaging technologies are key to next-generation tracking systems for high-energy physics, where radiation hardness and precise vertex reconstruction are essential. As part of the ALICE ITS3 R&D program in synergy with the CERN R&D, we evaluated the performance of the Analog Pixel Test Structures (APTS) fabricated in the TPSCo 65 nm CMOS imaging process. The prototypes employ 10 um pitch pixels with a fast operational amplifier-based buffering stage at the output, enabling direct characterization of intrinsic sensor response. Beam tests with minimum ionizing particles assessed the timing and charge collection of DC- and AC-coupled designs, including devices exposed to 10^14 NIEL and 10^15 NIEL non ioninsing energy loss. DC-coupled sensors demonstrated stable performance, maintaining time resolution lower than 70 ps and >99% detection efficiency up to 10^15 NIEL. AC-coupled sensors demonstrated a wide operational margin, with efficiencies above 99% for clusterization thresholds below 150 electrons. Even though the AC coupling allows higher reverse bias than DC-coupled sensors, the reduced signal amplitude lowers the signal-to-noise ratio, increasing the jitter contribution. At high reverse bias, the AC-coupled sensors achieve time resolutions comparable to the DC-coupled version, demonstrating the viability of both approaches. These results also suggest that combining the low capacitance of DC-coupled designs with the high-bias capability of AC coupling could further enhance time resolution. These results confirm the suitability of 65 nm MAPS for future collider detectors requiring high radiation tolerance, efficiency, and timing precision.

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Publication Details

Journal
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
Published
2026-05-12
DOI
https://doi.org/10.1016/j.nima.2026.171622
Primary Topic
Particle Detector Development and Performance
Type
article
Field-Weighted Citation Impact
0.00

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Influence of radiation and AC coupling on time performance of analog pixels test structures in 65 nm CMOS technology

W. Snoeys, A. Grelli, C. Ferrero, D. Colella et al.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
Particle Detector Development and Performance
article

Influence of radiation and AC coupling on time performance of analog pixels test structures in 65 nm CMOS technology

W. Snoeys, A. Grelli, C. Ferrero, D. Colella, P. Martinengo, M. Fransen, Umberto Savino, Triloki Triloki, M. Šuljić, D. Elia, G. Bruno, Jory Sonneveld, F. Piro, F. Benotto, F. Loddo, L. Ramello, E. Botta, F. Licciulli, H. Hillemanns, M. Antonelli, F. Reidt, Bong-Hwi Lim, Stefania Perciballi, G. Contin, C. Pastore, S. Beolè, Luca Aglietta, Shyam Kumar, R. Russo, S. Senyukov, Mario Sitta, Magnus Mager, Angelo Colelli, Isis Pihn Marie Hobus, Giuseppe De Robertis, Gianluca Aglieri Rinella, Valerio Sarritzu, F. Barile, F. Prino, R. N. Patra, Floarea Dumitrache, D. Marras, Alex Kluge, Esther Mwetaminwa M Bilo
article en

Abstract

Monolithic Active Pixel Sensors (MAPS) in advanced CMOS imaging technologies are key to next-generation tracking systems for high-energy physics, where radiation hardness and precise vertex reconstruction are essential. As part of the ALICE ITS3 R&D program in synergy with the CERN R&D, we evaluated the performance of the Analog Pixel Test Structures (APTS) fabricated in the TPSCo 65 nm CMOS imaging process. The prototypes employ 10 um pitch pixels with a fast operational amplifier-based buffering stage at the output, enabling direct characterization of intrinsic sensor response. Beam tests with minimum ionizing particles assessed the timing and charge collection of DC- and AC-coupled designs, including devices exposed to 10^14 NIEL and 10^15 NIEL non ioninsing energy loss. DC-coupled sensors demonstrated stable performance, maintaining time resolution lower than 70 ps and >99% detection efficiency up to 10^15 NIEL. AC-coupled sensors demonstrated a wide operational margin, with efficiencies above 99% for clusterization thresholds below 150 electrons. Even though the AC coupling allows higher reverse bias than DC-coupled sensors, the reduced signal amplitude lowers the signal-to-noise ratio, increasing the jitter contribution. At high reverse bias, the AC-coupled sensors achieve time resolutions comparable to the DC-coupled version, demonstrating the viability of both approaches. These results also suggest that combining the low capacitance of DC-coupled designs with the high-bias capability of AC coupling could further enhance time resolution. These results confirm the suitability of 65 nm MAPS for future collider detectors requiring high radiation tolerance, efficiency, and timing precision.

Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated EquipmentVol. 1090
Ministerstvo Školství, Mládeže a Tělovýchovy, National Research Foundation of Korea, National Science and Technology Development Agency, Suranaree University of Technology, HORIZON EUROPE Framework Programme, Ministero dell'Istruzione e del Merito
Openalex Percentile: Top 95%
Particle Detector Development and Performance
DOIOpen Access PDFOpenAlex
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