A Back Illuminated 10μm SPAD Pixel Array Comprising Full Trench Isolation and Cu-Cu Bonding with Over 14% PDE at 940nm

Ito, Ken; Otake, Yusuke; Kitano, Yasuyuki; Matsumoto, Atsushi; Yamamoto, Jiro; Ogasahara, Takayuki; Hiyama, Hirokuni; Ryosuke, Naito; Takeuchi, K.; Tada, Tsukasa; Takabayashi, Kazumasa; Nakayama, Hiroki; Tatani, K.; Hirano, Takuichi; Wakano, T.

doi:10.1109/iedm13553.2020.9371944

Cited by 22 publications

(36 citation statements)

References 4 publications

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“…Despite the degradation of the PDE by metal reflections, the presented FSI device achieves a competitive NIR PDE. Additionally, P ap exceeds the state-of-the-art [8] due to the small active region. Unlike typical SPADs with thick depleted absorption volumes [19], the device is compatible with a standard CMOS readout (enabled by V e = 3.5 V), and the pitch is not limited by a guard ring.…”

Section: Discussionmentioning

confidence: 94%

“…The lack of isolation negatively affects the NIR timing resolution and crosstalk of the FSI SPAD, as is the case for other nonisolated SPADs [14,18]. However, since the absorption volume is depleted, back-side illumination (BSI) and deep-trench isolation (as in [8]) can greatly improve isolation while enhancing the PDE and timing resolution. Additionally, V bd < 40 V and a lower R r can be obtained when reducing the epi thickness and optimizing the doping.…”

Section: Discussionmentioning

confidence: 99%

“…A disadvantage of silicon is the low absorption coefficient in the near-infrared (NIR) spectrum. To optimize the photon detection efficiency (PDE), red and NIR-enhanced silicon SPADs incorporate thick absorption regions using standard [8,[10][11][12][13][14][15][16][17][18] or customized [19][20][21] technologies. Carriers generated in the absorption volume move towards an electric field peak where they can trigger avalanche breakdown.…”

Section: Introductionmentioning

confidence: 99%

“…Prominent application domains of SPADs include time-of-flight (ToF) imaging [1][2][3] and biophotonics [4][5][6]. In particular, the use of ToF SPAD imagers for range-finding has gained increased interest from the automotive and mobile industries [7,8]. The application benefits from the integration of SPADs into uniform arrays.…”

Section: Introductionmentioning

confidence: 99%

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A Near-Infrared Enhanced Silicon Single-Photon Avalanche Diode With a Spherically Uniform Electric Field Peak

Sieleghem

Süss

Boulenc³

et al. 2021

IEEE Electron Device Lett.

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A near-infrared (NIR) enhanced silicon single-photon avalanche diode (SPAD) fabricated in a customized 0.13 µm CMOS technology is presented. The SPAD has a depleted absorption volume of approximately 15 µm × 15 µm × 18 µm. Electrons generated in the absorption region are efficiently transported by drift to a central active avalanche region with a diameter of 2 µm. At the operating voltage, the active region contains a spherically uniform field peak, enabling the multiplication of electrons originating from all corners of the device. The advantages of the SPAD architecture include high NIR photon detection efficiency (PDE), drift-based transport, low afterpulsing, and compatibility with an integrated CMOS readout. A front-side illuminated device is fabricated and characterized. The SPAD has a PDE of 13% at wavelength 905 nm, an afterpulsing probability < 0.1% for a dead time of 13 ns, and a median dark count rate (DCR) of 840 Hz at room temperature. The device shows promising performance for time-of-flight applications that benefit from uniform NIR-sensitive SPAD arrays.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Near-Infrared Enhanced Silicon Single-Photon Avalanche Diode With a Spherically Uniform Electric Field Peak

Sieleghem

Süss

Boulenc³

et al. 2021

IEEE Electron Device Lett.

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“…Yet, the most recent advance in CMOS technology for dToF is 3D-stacking with face to face bonding of top-tier BSI SPAD wafer with an advanced digital CMOS wafer bottom-tier (3D-BSI) [39]. The BSI SPAD is placed directly above the pixel circuit, a recent example showing a 90nm 1ML / 45nm 11ML stack is given in [40]. There are further benefits to stacked technology for dToF: cost reduction or performance increase and independent technology development and optimization of digital CMOS and SPAD diode processes.…”

Section: A Technology Trendsmentioning

confidence: 99%

Direct Time-of-Flight Single-Photon Imaging

Gyöngy

Dutton

Henderson

2022

IEEE Trans. Electron Devices

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This paper provides a tutorial introduction to the direct Time of Flight (dToF) signal chain and typical artifacts introduced due to detector and processing electronic limitations. We outline the memory requirements of embedded histograms related to desired precision and detectability which are often the limiting factor in the array resolution. A survey of integrated CMOS dToF arrays is provided highlighting future prospects to further scaling through process optimization or smart embedded processing. Index Terms-direct time-of-flight (dTOF), light detection and ranging (LiDAR), single photon avalanche diode (SPAD), silicon photo multiplier (SiPM), CMOS Image Sensor (CIS), SPAD array, 3D ranging

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Single Photon Kilohertz Frame Rate Imaging of Neural Activity

et al. 2022

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Establishing the biological basis of cognition and its disorders will require high precision spatiotemporal measurements of neural activity. Recently developed genetically encoded voltage indicators (GEVIs) report both spiking and subthreshold activity of identified neurons. However, maximally capitalizing on the potential of GEVIs will require imaging at millisecond time scales, which remains challenging with standard camera systems. Here, application of single photon avalanche diode (SPAD) sensors is reported to image neural activity at kilohertz frame rates. SPADs are electronic devices that when activated by a single photon cause an avalanche of electrons and a large electric current. An array of SPAD sensors is used to image individual neurons expressing the GEVI Voltron-JF525-HTL. It is shown that subthreshold and spiking activity can be resolved with shot noise limited signals at frame rates of up to 10 kHz. SPAD imaging is able to reveal millisecond scale synchronization of neural activity in an ex vivo seizure model. SPAD sensors may have widespread applications for investigation of millisecond timescale neural dynamics.

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A Back Illuminated 10μm SPAD Pixel Array Comprising Full Trench Isolation and Cu-Cu Bonding with Over 14% PDE at 940nm

Cited by 22 publications

References 4 publications

A Near-Infrared Enhanced Silicon Single-Photon Avalanche Diode With a Spherically Uniform Electric Field Peak

A Near-Infrared Enhanced Silicon Single-Photon Avalanche Diode With a Spherically Uniform Electric Field Peak

Direct Time-of-Flight Single-Photon Imaging

Single Photon Kilohertz Frame Rate Imaging of Neural Activity

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