In Framework of CERN RD50 Collaboration J.Hrknen, 10th ESSD, Wildbad - - PowerPoint PPT Presentation

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In Framework of CERN RD50 Collaboration J.Hrknen, 10th ESSD, Wildbad - - PowerPoint PPT Presentation

Jan 01, 2024 220 likes •368 views

Thermal donor generation in Czochralski silicon particle detectors M.Bruzzi 1) , J.Hrknen 2) , Z. Li 3) , P.Luukka 2) , D. Menichelli 1 ) , E. Tuovinen 1) 1) University of Florence 2) Helsinki Institute of Physics, CERN/PH, Switzerland 3)

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SLIDE 1

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20 Thermal donor generation in Czochralski silicon particle detectors

1) University of Florence 2)Helsinki Institute of Physics, CERN/PH, Switzerland 3)Brookhaven National Laboratory, Upton, NY11973-5000, USA

In Framework of CERN RD50 Collaboration

M.Bruzzi1), J.Härkönen2), Z. Li3), P.Luukka2), D. Menichelli1), E. Tuovinen1)

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SLIDE 2

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

OUTLINE

  • Introduction of TDs
  • Motivation
  • Thermal Donors (TD) in oxygen

rich silicon

  • Processing of MCz-Si detectors with

TDs

  • Conclusions
  • DLTS spectra
  • Annealing of p-type MCz-Si with TDs
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SLIDE 3

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Motivation

  • By introduction of TDs, the Vfd
  • f detectors can be adjusted in

wide range

  • n+/p-/p+ detector signal comes from electrons having three times

higher mobility than the holes

  • The detectors used in particle

tracking systems must be fully depleted at reasonably low

  • perating voltage
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SLIDE 4

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Thermal Donors in Cz-Si

  • TDs are oxygen complexes that form shallow states in Si band gap

below the conduction band.

  • High O content leads to Thermal Donor (TD) formation at

temperatures 4000C – 6000C.

  • Typical process steps at 4000C – 6000C
  • Aluminum sintering

(e.g. 30min @ 4500C)

  • Passivation insulators over metals

(LTO,TEOS etc ~6000C + H2 from Si3H4 process gas)

  • TD formation can be enhanced if H is present.

D.J. Chadi, Phys. Rev. Lett. 77, 861–864 (1996)

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SLIDE 5

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Thermal Donor generation

MCz-Si, Oi≈4,9*1017 cm-3 Cz-Si, Oi≈8*1017 cm-3 Oxygenated Fz-Si, Oi≈1*1017 cm-3

68V 685V

  • TD formation depends on
  • O concentration in silicon
  • Temperature
  • Amount of H in detector processing
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SLIDE 6

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Sample processing

  • n+/p-/p+ diodes with p-stops
  • TD generation 35 and 45 minutes
  • 5 mask levels
  • p+/p-/p+ diodes
  • TD generation 60,70 and 80 minutes
  • 4 mask levels
  • TD induced type-inversion
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SLIDE 7

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Thermal Donor generation (experimental results)

  • O concentration from FTIR

measurements

  • Thick reference wafer
  • Center 4,95*1017 cm-3
  • Right 4,89*1017 cm-3
  • Left 4,93*1017 cm-3
  • Right 4,93*1017 cm-3
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SLIDE 8

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Thermal Donor generation (experimental results)

1E+12 2E+12 3E+12 4E+12 5E+12 6E+12 7E+12 8E+12 9E+12 1000 2000 3000 4000 5000 6000

Time (s) Ntd(cm^-3)

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SLIDE 9

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Thermal Donor generation (experimental results)

  • 4E+12
  • 3E+12
  • 2E+12
  • 1E+12

1E+12 2E+12 3E+12 4E+12 5E+12 6E+12

1000 2000 3000 4000 5000 6000 7000

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SLIDE 10

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Leakage current

0,0E+00 5,0E-10 1,0E-09 1,5E-09 2,0E-09 2,5E-09 3,0E-09 3,5E-09 4,0E-09 4,5E-09

  • 300
  • 250
  • 200
  • 150
  • 100
  • 50

Voltage [V] Current [A]

no TD no TD TD 45min at 430C TD 45min at 430C

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SLIDE 11

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Deep Level Transient Spectroscopy

  • Sample heated at 430C 45 minutes
  • Sample heated at 370C 45 minutes
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SLIDE 12

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Annealing of proton irradiated detectors

50 100 150 200 250 300 350 400 450 1 10 100 1000

Heating time at 80C (min) Vfd (V)

n Cz-Si TD's 60min TD's 70min TD's 80min

  • 1,5*1014 cm-2 1MeV

neutron equivalent.

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SLIDE 13

J.Härkönen, 10th ESSD, Wildbad Kreuth June 20

Conclusions

  • Thermal Donors can be introduced into MCz-Si detectors at 430°C during

the aluminum sintering.

  • Effective resistivity range is very wide in TD-process 500Ωcm < σ < ∼10

kΩcm

  • With this method it is possible to

adjust the Vfd of p-type MCz-Si

n+/p-/p+ detectors

  • It is low temperature, low cost process, no additional process complexity >>

feasible solution for large scale experiments ?

  • No increase of leakage current