wodean workshop, vilnius university 02/03-june-2007
DESCRIPTION
Macroscopic Effects in n-MCz Diodes after Neutron Irradiation Depletion Voltage and Reverse Current. G. Lindstroem a , E. Fretwurst a , F. Hönniger a , A. Junkes a , K. Koch a and I. Pintilie a,b - PowerPoint PPT PresentationTRANSCRIPT
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Gunnar Lindstroem – University of Hamburg 1
G. Lindstroem a, E. Fretwurst a, F. Hönniger a, A. Junkes a, K. Koch a and I. Pintilie a,b
a Institute for Exp. Physics, University of Hamburgb National Institute for Materials Physics NIMP, Bucharest
Macroscopic Effects in n-MCz Diodes after Neutron Irradiation Depletion Voltage and Reverse Current
WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 2
Outline:
1. Properties of used diodes
2. Effective doping
3. Reverse current
4. Conclusions
WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 3
Used material: WODEAN n-MCZ (OKMETIC), P-doped 900 cm, Neff = 4.8E+12 cm-3
Diode processing: CiS Erfurt, thinned to d = 95 mrear contact: P-implanted: Neff = 4.8E+12 cm-3
P-diffused: Neff = 7.7E+12 cm-3
(TD generation during thermal process)
WODEAN workshop, Vilnius University 02/03-June-2007
0 20 40 60 80 100
depth [m]
1015
1016
1017
1018
O-c
onc.
[1/
cm3 ]
8556-01 [O], full process8556-01 [O], full process8556-01 [C], full process8556-01 [C], full process
SIMS O-profiles, 300 m n-MCz
Adam Barcz, ITE WarsawAdam Barcz, ITE Warsaw
[O] = 5e17/cm3, [O] = 5e17/cm3,
[C] < 3e15/cm3 (detection limit)[C] < 3e15/cm3 (detection limit)
O and C concentration:
[O] = 5E+17 cm-3
(outdiffusion below 10 m)
[C] < 3E+15 cm-3
(detection limit)
Diode properties
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Gunnar Lindstroem – University of Hamburg 4WODEAN workshop, Vilnius University 02/03-June-2007
Effective doping concentration Dependence on and annealing
-General Reminder-
10-1 100 101 102 103
eq [ 1012 cm-2 ]
1
510
50100
5001000
5000
Ude
p [V
] (
d =
300
m)
10-1
100
101
102
103
| Nef
f | [
1011
cm
-3 ]
600 V
1014cm-2
type inversion
n-type "p-type"
[M.Moll: Data: R. Wunstorf, PhD thesis 1992, Uni Hamburg]
300 m diodes not usable up to 1E+16 n/cm²full depletion voltage exceeds 10 KV!
Cure: use of lower resistivity and thin diodes,hence 100 m and <1kcm
High resistivity FZ silicon:
NC
NC0
gC eq
NYNA
1 10 100 1000 10000annealing time at 60oC [min]
0
2
4
6
8
10
N
eff [
1011
cm-3
]
[M.Moll, PhD thesis 1999, Uni Hamburg]
Annealing function –“Hamburg model“
Short term: beneficial annealingLong term: reverse annealing
time constants depending on temperature!Tann = 80C: 100 to 1000 min (rev.anneal) Tann = RT: 1 to 10 years
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Gunnar Lindstroem – University of Hamburg 5WODEAN workshop, Vilnius University 02/03-June-2007
Nmin ≈ NC
NY
Annealing function for n-MCz 100 m diodes
N = Neff,0-Neff(,t) = Na(,tann) + NC0(1-exp(-c)) + gC· + NY(,tann)
Na: beneficial annealingNC: stable damage, NC0(1-exp(-c)): donor removal (NC0 = Neff,0)
gC: acceptor generationNY: reverse annealing (increase of neg. space charge during annealing)
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Gunnar Lindstroem – University of Hamburg 6WODEAN workshop, Vilnius University 02/03-June-2007
Annealing time constants
All values measured for Tanneal = 80 °C, no real difference to known results from other Si-diodes (FZ, epi)
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Gunnar Lindstroem – University of Hamburg 7WODEAN workshop, Vilnius University 02/03-June-2007
Annealing time constants
All values measured for Tanneal = 80 °C, no real difference to results from MCz with standard process
Annealing behaviour not affected by thermal donors!
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Gunnar Lindstroem – University of Hamburg 8WODEAN workshop, Vilnius University 02/03-June-2007
Beneficial annealing amplitude
Saturation fit for Na() misleadingAt =3E+15 n/cm²: tirrad = 25 min, Tirrad = 70-80 °C
hence strong self annealing during annealing!Linear fit for ≤ 1E+15 n/cm² reliable
ga = 1.2E-2 cm-1
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Gunnar Lindstroem – University of Hamburg 9WODEAN workshop, Vilnius University 02/03-June-2007
Stable damage component NC
Remember: NC = NC0(1-exp(-c)) + gCC0 = Neff,0 if only P-doping donor removal by formation of E-center (VP)!
Rear side P-implanted: NC0 = 5E+12/cm³ ≈ Neff,0: ok☺Rear side P-diffused: NC0 similar to P-implanted: P-donors removedThermal donor concentration = 2E+12/cm³, stays constant during annealing
donor removal rate c ≈ 1E-14 cm², NC0*c ≈ 5E-2 cm-1: ok ☺acceptor introduction rate = 9E-3cm-1: about 2x larger than for thin FZ, epi!
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Gunnar Lindstroem – University of Hamburg 10WODEAN workshop, Vilnius University 02/03-June-2007
Comparison of Neff() at Nmin measured in thin diodes
For tanneal = 8 min at 80 °C
n-MCz
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Gunnar Lindstroem – University of Hamburg 11WODEAN workshop, Vilnius University 02/03-June-2007
Side remark (not WODEAN):
Comparison between 50 m n-type and p-type epi diodes after n-irradiation
n-type epi: P-donor removal (small ) + BD donor generation (large )p-type epi: B-acceptor removal (small ) + acceptor generation (large )
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Gunnar Lindstroem – University of Hamburg 12WODEAN workshop, Vilnius University 02/03-June-2007
Reverse annealing amplitude NY
Assumed annealing function: 1st and 2nd order for best fitNY = sum of both amplitudes reliable!
Saturation fit with acceptor introduction rate for small : gY0 = 5E-2 cm-1in agreement with other materials
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Gunnar Lindstroem – University of Hamburg 13WODEAN workshop, Vilnius University 02/03-June-2007
Reverse current
Annealing function for in comparison to p-epi Linear fit for IFD/Vol as fct. of
Shape of annealing function does not differ significantly from other known results (see RD50 talk E. Fretwurst)
Linear fit for IFD/Vol = · gives = 4.1E-17Acm-1which is the generally accepted value
Results are in general agreement with known datasome deviations of annealing function (as for all thin
diodes) from the old fit (M. Moll)
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Gunnar Lindstroem – University of Hamburg 14WODEAN workshop, Vilnius University 02/03-June-2007
Conclusions
• general behaviour of n-MCz diodes as known for other material although [O] = 5E+17 cm-2 is large
• thermal donors generated in n-MCz before irradiation are not affected by radiation damage
• Complete donor removal observed with rate constant c ≈ 1E-14 cm²
• Acceptor introduction rate gC = 9E-3 cm-1 about 2 x larger than for other known materials
• Reverse current in accordance with other data = 4.1E-17 Acm-1
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Gunnar Lindstroem – University of Hamburg 15WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 16WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 17WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 18WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 19WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 20WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 21WODEAN workshop, Vilnius University 02/03-June-2007
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Gunnar Lindstroem – University of Hamburg 22WODEAN workshop, Vilnius University 02/03-June-2007
0 5 10 15 20 25
depth [m]
1016
51017
51018
51019
51020
51021
D-c
onc.
[1/
cm3 ]
as implantedas implanted1h@400C annealing in Ar with nitide off1h@400C annealing in Ar with nitide off1h@400C annealing in Ar with nitride on1h@400C annealing in Ar with nitride on
D-concentration profile from implantation before and after annealing
Hydrogenation of Silicon – First Attempts
Implantation of 710 keV D, R = 7 m