Institut fr Kernphysik Frankfurt for the CBM-MVD-collaboration - - PowerPoint PPT Presentation

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Institut fr Kernphysik Frankfurt for the CBM-MVD-collaboration - - PowerPoint PPT Presentation

Apr 04, 2023 162 likes •337 views

AD vanced MO nolithic S ensors for An X-ray fluorescence spectrometer using CMOS-sensors Dennis Doering, Michael Deveaux Institut fr Kernphysik Frankfurt for the CBM-MVD-collaboration Sensor development: IPHC Strasbourg 1) Real-time water

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SLIDE 1

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An X-ray fluorescence spectrometer using CMOS-sensors

ADvanced MOnolithic Sensors for Supported by BMBF (06FY9099I and 06FY7113I), HIC for FAIR, GSI and EU-FP7

1) Real-time water analysis using XRF 2) CMOS-Sensors 3) Reconstruction of the energy information 4) Improving the quantum efficiency Dennis Doering, Michael Deveaux Institut für Kernphysik Frankfurt for the CBM-MVD-collaboration Sensor development: IPHC Strasbourg

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SLIDE 2

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Application: X-ray spectrometer

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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Monitoring water quality and trigger on traces of pollution Identifing elements via their characteristic X-ray-fluorescence lines (XRF) Required sensor features:

  • Good energy resolution
  • High-rate capability

⇒ Adapted CMOS-sensors

  • Low noise
  • Low production costs

Sample

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SLIDE 3

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Operation principle of CMOS-sensors

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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SiO2 SiO2 SiO2 N+ P+

P- P+

Diode Epitaxial Layer P-Well Substrate N+

Particle

Depleted zone

e- e-

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SLIDE 4

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Charge smearing between pixels

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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P- P+ Diode Epitaxial Layer P-Well Photon Depleted zone

2 4 6 8 10 12 14 16 18 20 22 24 26 200 400 600 800 1000

Pixel charge smearing Ag Kβ Ag Kα (cal) One "seed" pixel Fluorescence spectrum of the setup

Counts [1/36e] Collected electrons [ke]

One pixel:

e- e- Cd-109-source (support is built up

  • f brass)

Ag Kα,Kβ Chip (PCB contains Ba)

Drawback: Charge smearing +20°C

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SLIDE 5

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Cluster of 25 pixels

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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P- P+ Diode Epitaxial Layer P-Well Photon Depleted zone

Cluster of 25 pixels

e- e-

Disadvantage: Noise contribution of 25 pixels

2 4 6 8 10 12 14 16 18 20 22 24 26 200 400 600 800 1000

Cu Kα Ba Lα Ag Kβ Ag Kα (cal) One "seed" pixel Cluster Fluorescence spectrum of the setup

Counts [1/36e] Collected electrons [ke]

Cd-109-source (support is built up

  • f brass)

Ag Kα,Kβ Chip (PCB contains Ba)

+20°C

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SLIDE 6

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Trigger on conversions in the depleted zone

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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P- P+ Diode Epitaxial Layer P-Well Photon Depleted zone e- e-

2 4 6 8 10 12 14 16 18 20 22 24 26 50 100 150 200 250

Ba Lα V Kα Cu Kα Zn Kα Ag Kβ Ag Kα (cal) Depleted zone Fluorescence spectrum of the setup

Counts [1/36e] Collected electrons [ke]

Cd-109-source (support is built up

  • f brass)

Ag Kα,Kβ Chip (PCB contains Ba)

Triggercondition: Neighboring pixel carry no charge +20°C

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SLIDE 7

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Trigger on conversions in the depleted zone

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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P- P+ Diode Epitaxial Layer P-Well Photon Depleted zone e- e-

2 4 6 8 10 12 14 16 18 20 22 24 26 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000

Ba Lα V Kα Cu Kα Zn Kα Ag Kβ Ag Kα (cal) Depleted zone Cluster Fluorescence spectrum of the setup

Counts [1/36e] Collected electrons [ke]

Cd-109-source (support is built up

  • f brass)

Ag Kα,Kβ Chip (PCB contains Ba)

Drawback: Reduced quantum efficiency +20°C

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SLIDE 8

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Linearity of amplification chain

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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100 200 300 400 500 600 700 5 10 15 20 25

Zn Kα Cu Kα V Kα Energy of the identified peak [keV] Charge collected [ADC] Ba Lα Ag Kβ Ag Kα Mn Kα Mn Kβ

Energy[keV]=(0.0364±0.0004) · Qcoll[ADC]+(-0.004±0.05) Linear energy scale at least between a few keV up to 25keV +20°C

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SLIDE 9

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Strategies to increase the quantum efficiency

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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Larger depleted volumes: ⇒ Accelerated charge collection, less diffusion ⇒ Less charge smearing between pixels Aim: Full depletion of the epitaxial layer

SiO2 N+ P+ P- P+ Epitaxial Layer P-Well Substrate

depleted volume Low-resistivity ~ 30 Ωcm High-resistivity ~1k Ωcm High-resistivity: Decrease of doping concentration in epitaxial layer. Depletion voltage: Increase the depleted volume

Sensing diode

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SLIDE 10

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TOWER-Jazz-Process

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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Larger depleted volumes: ⇒ Accelerated charge collection, less diffusion ⇒ Less charge smearing between pixels Aim: Full depletion of the epitaxial layer

SiO2 N+ P+ P- P+ Epitaxial Layer P-Well Substrate

depleted volume Low-resistivity ~ 30 Ωcm High-resistivity ~1k Ωcm High-resistivity: Decrease of doping concentration in epitaxial layer. Depletion voltage: Increase the depleted volume

Sensing diode

TOWER-Jazz-0.18µm process

  • High-Resistivity 1-8kΩcm
  • Depletion voltage up to 20V

Modified preamplifier

  • Recharge diode
  • AC-coupled
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SLIDE 11

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TOWER-Jazz 0.18µm CMOS process for imager

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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The Sensor: PEGASUS (2015) 18µm thick, 25µm pixel pitch, >1kΩcm epitaxial layer, 12 V bias voltage

Cd-109-source Cu-foil Ag Kα,Kβ

2 4 6 8 10 12 14 16 18 20 22 24 26 28 75 150 225 300

Cu Kβ Ag Lα Ag Kβ One "seed" pixel Pegasus, T= +20°C Cd-109-source

Counts [1/40 e] Collected energy [keV]

Cu Kα Ag Kα Calibration peak

Less charge smearing ⇒ Larger depletion zone

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SLIDE 12

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TOWER-Jazz 0.18µm CMOS process for imager

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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The Sensor: PEGASUS (2015) 18µm thick, 25µm pixel pitch, >1kΩcm epitaxial ayer, 12 V bias voltage

Cd-109-source Cu-foil Ag Kα,Kβ

Less charge smearing ⇒ Larger depletion zone Trigger on neighboring pixels still helps

2 4 6 8 10 12 14 16 18 20 22 24 26 28 75 150 225 300

Cu Kβ Ag Lα Ag Kβ One "seed" pixel Depleted zone Pegasus, T= +20°C Cd-109-source

Counts [1/40 e] Collected energy [keV]

Cu Kα Ag Kα Calibration peak

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SLIDE 13

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Influence of the leakage current

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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Due to the non-linear response

  • f the recharge diode at +20°C :
  • Limited energy resolution
  • Non-linear amplification

⇒ Optimizing of the pixel layout required (Pegasus-3) ⇒ Cooling to -20°C so far helps

6,0 6,5 7,0 7,5 8,0 8,5 9,0 9,5 10,0 100 200 300 400 500 600 700 800 900 1000

T= +20°C Cu-Kα= 8135 eV T= -20°C Cu-Kα= 8035 eV

Counts [1/80 e] Collected energy [keV]

Literature: Cu-Kα1=8047 eV Cu-Kα2=8027 eV

20,0 20,5 21,0 21,5 22,0 22,5 23,0 23,5 24,0 50 100 150 200 250 300 350 400 450 500 550 600

T= +20°C T= -20°C

Counts [1/80 e] Collected energy [keV]

σ+20°C=637eV σ-20°C=215eV

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SLIDE 14

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Cu-inlay

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016

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Cd-109-source Cu-foil Ag Kα,Kβ Ag Kα,Kβ +Cu Kα

2 4 6 8 10 12 14 16 18 20 22 24 26 28 150 300 450 600 750 900 1050 1200 1350

Cu Kβ Ag Lα Ag Kβ Reference Cu-inlay Pegasus, T= -20°C Cd-109-source

Counts [1/80 e] (norm. to detected Ag Kα-Photons) Collected energy [keV]

Cu Kα =8040 eV σ=122eV Ag Kα

Expected excess in Cu-Kα-line observed Energy resolution is σ=122eV

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SLIDE 15

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Conclusion

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Application: Real-time water analysis via X-ray fluorescence analysis ⇒ CMOS-Sensors proposed Studied two CMOS-sensors: MIMOSA-19 and Pegasus Possible above 2 keV with an energy resolution of 120…190eV At room temperature or slightly cooled conditions ⇒ Sensors seem suited for the task Outlook: Obtain higher quantum efficiency due to full depleted epitaxial layer Detailed study of high-voltage CMOS-sensors required DFG proposal submitted

  • M. Deveaux, D. Doering: An XRF spectrometer using CMOS-sensors DPG Darmstadt March 2016