A Low Temperature Technology on the Base of Hydrogen Enhanced Thermal Donor Formation
for Future High-Voltage Applications
R. Job 1, A.G. Ulyashin 1, W.R. Fahrner 1, 1 University of Hagen, Dept. of Electrical Engineering and Information
Technology (LGBE), GermanyF.J. Niedernostheide 2, H.J. Schulze 2,
2 Infineon AG, Munich, GermanyE. Simoen 3, C.L. Claeys 3, 4,
3 IMEC, Leuven, Belgium4 University of Leuven (KU), Dept. of Electrical Engineering, Belgium
G. Tonelli 5 5 INFN, Pisa, Italy
Dr. Reinhart Job, University of Hagen, Germany
Outline of the Talk
• Introduction
• Experimental (substrates, H-plasma treatments & annealing)
• Experimental Results (analysis by SRP measurements, I-V and C-V curves, DLTS, Raman spectroscopy, SEM, TEM )
• Discussion (low temperature doping by thermal donors low thermal budget technology for special devices,i.e. high-voltage devices, radiation detectors, etc.)
• Summary
Dr. Reinhart Job, University of Hagen, Germany
Thermal Donors (TDs)
• 'Old thermal donors' (TDs), oxygen related double donors (TDDs)– formation at T 300 - 500 °C
– T > 550 °C TDs are dissolved
– family of 'bistable' double donors TDD1, TDD2, ... , TDD16, ... (?)
– classification by IR-absorption spectroscopy
– 2 energy levels of the donor: 70 meV, 150 meV
– formation rate R correlated with [Oi] and [Cs]: [Oi] high R high, [Cs] high R low
• Our investigations: 'Old thermal donors' (i.e. TDDs)
• Other types of TDs: NDs, NTDs, STDs
Dr. Reinhart Job, University of Hagen, Germany
Thermal Donors• 'New donors' (NDs)
– formation at T 550 - 800 °C– R correlated with [Oi] and [Cs]:
[Oi] high R high, [Cs] high R high– energy level of the donor: 17 meV
• 'New thermal donors' (NTDs)– formation at T 300 - 500 °C– NTDs appear only after very long annealing times (> 105 min)– NTDs double donors– large agglomerates of oxygen (?)
• 'Shallow thermal donors' (STDs)– formation at T 300 - 500 °C (low concentrations)– family of 7 single donors
Dr. Reinhart Job, University of Hagen, Germany
Low Thermal Budget Doping by Thermal Donors
• Hydrogen enhances thermal donor (TD) formation in Cz silicon
• Thermal donors: 'old' TDs, i.e. TDDs (oxygen related double donors)
• Counter doping of initial p-type Cz Si by hydrogen enhanced TD formation formation of deep p-n junctions
• Developed process routes:- "1-step-process"- "2-step-process"
Dr. Reinhart Job, University of Hagen, Germany
Experimental
• Substrates:
– p-type Cz Silicon wafers( = 3 inches, d 370 - 380 µm, (100)-oriented)
Impurities:
[Oi] 7 - 81017 cm-3 (specified, IR-Absorption)
[Cs] < 51016 cm-3 (specified)
Doping: = 12 - 20 cm, = 5 - 10 cm, = 1 - 2 cm[B] 61014 cm-3 - 1.31016 cm-3
Dr. Reinhart Job, University of Hagen, Germany
ExperimentalApplied measurements:
“Spreading-Resistance-Probe”- (SRP-) measurements- resistance profiles in dependence on the depth- estimation of the location of p-n junctions
Thermoelectrical Microprobe Method (‘Seebeck-Effect’)- determination of the type of doping (n-type / p-type)
C(V) measurements- characterization of p-n junctions due to TD formation
Infrared- (IR-) absorption measurements- characterization of TD types (”TDDi- family")
I(V) measurements- characterization of diodes (”TD-Diodes”)
Dr. Reinhart Job, University of Hagen, Germany
"1-Step-Process" for TD Formation
• Hydrogen enhanced TD formation in Cz Si only by H-plasma treatment
• "1-step-process":TDD formation during H-plasma treatment(Tplasma = 400 - 450 °C, tplasma 30 min)
• Cz Si wafers: [B] = 11015 cm-3, [Oi] = 7 - 81017 cm-3
• Example: DC plasma treatment (RIE setup, 500 V plate voltage, 440 µA/cm2) formation of TDDs, [TDD] 11016 cm-3 formation of deep p-n junctions (counter doping)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
SRP measurements:
p-n junction location
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:30 min at 400 °C (1-step-process)
0 100 200 300 400 500103
104
105
106
30 min DC H-Plasma
Tpl = 400 °C
p-typen-type
p-n junctionSR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
Free carrier concen-tration Nc in depen-dence on the depth
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:30 min at 400 °C (1-step-process)
0 100 200 300 400 500 6001014
1015
1016
30 min DC H-Plasma
Tpl = 400 °C
n-type p-type
p-n junction
NA[N
c] (c
m-3
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
Electron concentra-tion Ne(TD) due to TDDs in dependence on the depth
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:30 min at 400 °C (1-step-process)
0 100 200 300 400 5001014
1015
1016
p-type
n-type
p-n junction
NAN
e(T
D) (
cm-3
)
Tiefe (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
C(V) measurements:
C-3 Vbias linear graded junction
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:30 min at 400 °C (1-step-process)
0 -5 -10 -15 -20 -25 -300
1x10 -6
2x10 -6
3x10 -6
4x10 -6
5x10 -6
C-3
(pF
-3)
VBIAS (V)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
SRP measurements:
p-n junction location
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:45 min at 400 °C (1-step-process)
0 100 200 300 400 500103
104
105
106
45 min DC H-Plasma / Tpl = 400 °C
p-typen-type
p-n junctionSR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
Free carrier concen-tration Nc in depen-dence on the depth
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:45 min at 400 °C (1-step-process)
0 100 200 300 400 5001014
1015
1016
45 min DC H-Plasma / Tpl = 400 °C
p-typen-type
pn-junction[N
c] (c
m-3
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
SRP measurements:
p-n junction depth in dependence on the initial p-type doping
Substrate:1, 12 cm Cz Si, [B] 1015, 1016 cm-3
(p-type)
H-Plasma:120 min at 400 °C (1-step-process)
0 100 200 300 400 500103
104
105
106
107
12 cm1 cm
120 min DC H-Plasma / Tpl = 400 °C
SR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
SRP measurements:
p-n junction depth in dependence on the amount of incorpo-rated hydrogen
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:120 min at 400 °C (1-step-process)
0 100 200 300 400 500103
104
105
106
107
108
120 min DC H-Plasma / T pl = 400 °C
440 µA cm -260 µA cm -2
SR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
C(V) measurements:
Ne(TD) in dependen-ce on the hydrogen dose
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:at 400 °C (1-step-process)
0 5x1018 1x1019 2x1019 2x10190
5x1015
1x1016
2x1016
2x1016
Ne(
TD
) (cm
-3)
H-dose (cm -2)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
SRP measurements:
p-n junction depth in dependence on the plasma treatment time
Substrate:12 cm Cz Si, [B] = 11015 cm-3
(p-type)
H-Plasma:30 - 120 min at 400 °C (1-step-process)
0 100 200 300 400 500103
104
105
106
107
DC H-Plasma / Tpl = 400 °C
120 min
45 min
30 min
SR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "1-Step-Process"
]H[K]H[Kt]H[
]H[K]H[K2x
]H[Dt]H[
222
12
222
12
2
H
DH: diffusion constant of atomic hydrogen
K1 : rate of H2 formation
K2 : dissociation constant of H2 molecules
Time dependences of H and H2 concentrations:
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "1-Step-Process"
kT48.0exp1067.9D
kTEexpK,DR8K
3H
b2H01
K1 : rate of H2 formationK2 : dissociation constant of H2 moleculesDH: "Van Wieringen-Warmholtz" relation diffusion constantR0 : capture radius (R0 = 5 Å *)) : vibration frequency of the dissociation of H2 Eb: binding energy (Eb = 1.6 eV)
*) J.T. Borenstein et al., J. Appl. Phys. 73, 2751 (1993)
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "1-Step-Process"
]H[Kt
]N[3
TD
NTD: concentration of thermal double donors ("TDD")
compensation (p-n junction): 2 [NTD] = [B]K3 : free parameter (deduced by fitting of experimental data)
K3 = 3.810-2 s-2
Boundary condition:
x = 0, t 0: [H0], with [H0] = 1014 cm-3
(constant hydrogen concentration at the wafer surface)
Time dependence of [TD] :
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")Simulated curves:
[TDD], [H], [H2] in dependence on the depth
Assumption:T = 400 °Ct = 30 min(1-step-process)
[TDD]-profile:
K3 = 3.810-2 s-2 (Fit to exp. Data)
0 100 200 300 400 5001010
1011
1012
1013
1014
1015
1016
[H2]
[H]
[TDD]
[H],
[H2]
, [T
D] (
cm-3
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("1-Step-Process")
Comparison of simulated [TD] profiles & experimental data
Assumption:T = 400 °Ct = 30, 45, 120 min(1-step-process)
Fit to exp. Data:
K3 = 3.810-2 s-2 0 100 200 300 400 5001013
1014
1015
1016
1017
p-n junctions (exp.)
tplasma = 120 mintplasma = 45 mintplasma = 30 min
[TD
] (cm
-3)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "1-Step-Process"
Summary / Conclusions:• "1-Step-Process": various processes occur
– T > 200 °C no acceptor passivation – incorporation of hydrogen from the plasma ambient– formation and decay of H2 complexes
– diffusion of H via interstitial lattice sites– H lowers the barrier for the diffusion of Oi
– probability is enhanced that Oi forms a TD complex
hydrogen supports the TD formation – loss of Oi due to the incorporation of Oi into TD-complexes
Question: Charge state of hydrogen (H0, H+, H-) ?
Dr. Reinhart Job, University of Hagen, Germany
"2-Step-Process" for TD Formation• Hydrogen enhanced TD formation in Cz Si by H-plasma
treatment and subsequent annealing
• "2-step-process":TDD formation during post-hydrogenation annealing- H-plasma exposure: Tplasma 250 °C, tplasma = 60 min - annealing: Tanneal 450 °C, tanneal 15 min
• Cz Si wafers: [B] = 11015 cm-3, [Oi] = 7 - 81017 cm-3
• Example: PECVD plasma treatment (110 Mhz, 50 W, 440 µA/cm2) formation TDDs / p-n junctions, [TDD] 11016 cm-3
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("2-Step-Process")SRP measurements:
p-n junction depth in dependence on the post-hydrogenation annealing time
Substrate:1.8 - 2.6 cm Cz Si, [B] 71015 cm-3
(p-type)
H-Plasma:60 min at 250 °C Annealing:at 450 °C/air
0 100 200 300 400103
104
105
106
15'10'
= 1.8 - 2.6 cm
480'240'120'60'45'30'20'
wafer thickness: 367 + 5 µm
SR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("2-Step-Process")SRP measurements:
p-n junction depth in dependence on the post-hydrogenation annealing time
Substrate:5 - 10 cm Cz Si, [B] 21015 cm-3
(p-type)
H-Plasma:60 min at 250 °C Annealing:at 450 °C/air
0 100 200 300 400103
104
105
106
240' 480'
30' 120'60'45'10' 15' 20'
= 5 - 10 cm
wafer thickness: 378 + 5 µm
SR
(
)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "2-Step-Process"
• "2-step-process": 60 min RF H-plasma at 250 °C+ annealing at 450 °C/air
• Hydrogen supports the formation of TDs, i.e. TDDs
• Supposition: TD formation / depth of p-n junctions penetration of n-type regions into the wafer bulk are driven by H diffusion
• "Fick's Diffusion Law":
[H]: hydrogen concentration, D: diffusion constant, t: time,
]H)[D(t]H[
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "2-Step-Process"
• "Fick's Law":
• if D = const.
(D: diffusion constant, d: depth, t: time, [H0]: surface concentration)
• mean diffusion length:
• assume: p-n junction depth dpn proportional to diffusion length L: dpn L, i.e. dpn t1/2
tD4
derfc]H[]H[ 0
tD4L
]H)[D(t]H[
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("2-Step-Process")p-n junction depth:
description by the "Fick's diffusion law"
(D: diffusion constant)
linear slope
D = 2.9 10-7 cm2s-1 (5 - 10 cm Cz Si)
D = 7.9 10-7 cm2s-1
(1.8 - 2.6 cm Cz Si)
0 50 100 150 2000
100
200
300
400
= 5 - 10 cm
= 1.8 - 2.6 cm
Dep
th (
µm
)
t1/2 (s1/2)
tD4L
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "2-Step-Process"
• Relation of Van Wieringen and Warmholtz (VWW):
(Ea = 0.48 eV)
• VWW equation holds for atomic hydrogen !
• extrapolation to 450 °C: DVWW = 4.36 10-6 cm2/s
• experiment: D 7.9 10-7 cm2s-1 (1 cm Cz Si) D 2.9 10-6 cm2s-1 (5 cm Cz
Si)
TkEexp67.9D a
H
Dr. Reinhart Job, University of Hagen, Germany
Formation of p-n Junctions ("2-Step-Process")RF H-plasma exposure at room temperature:
p-n junction formation only after long time annealing at 450 °C (t > 8 hours)
Substrate:12 - 20 cm Cz Si, [B] 1.11015 cm-3
(p-type)
H-Plasma:60 min at RTAnnealing:at 450 °C/air
0 50 100 150 200 250 300Depth (microns)
104
105
106
107
SR
(Ohm
)
8h 30'
8h
8h 15'
p-n junction
p-n junction
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "2-Step-Process"Summary / Conclusions (1):
• Hydrogen is amphoteric (standard model: H+ in p-type Si, H0 and H- in n-type Si)
• Estimated diffusion constants neutral atomic hydrogen H0 plays the major role for the TD formation
• H0 is responsible for the enhancement of the TD formation in p-type and n-type Cz Si
• D(H0) is several orders of magnitude larger than the diffusion constant D(H+) of positively charged H+ ions
D(H0)/D(H+) 105 *)
*) D. Matthiot, Phys. Rev. B 40, 5867 (1989)
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "2-Step-Process"Summary / Conclusions (2):
• "2-Step-Process": various processes occur– T > 200 °C no acceptor passivation occurs
– T 250 °C immobile hydrogen complexes are created
– T 400 - 450 °C immobile hydrogen complexes are dissolved high concentration of mobile H0
– diffusion of H0 via interstitial lattice sites
– H0 lowers the barrier for the migration of Oi
– probability is enhanced that Oi forms a TD complex
hydrogen supports the TD formation
Dr. Reinhart Job, University of Hagen, Germany
Kinetic Analysis of the "2-Step-Process"Summary / Conclusions (3):
• Dominant reaction at T 250 °C (H-plasma treatment):H+ + H0 H2 + h+ *)
(H+, H0: hydrogen in positive, neutral state, h+: hole, compensated by crystal field) *) S.M. Myers et al., Rev. Mod. Phys. 64, 559 (1992)
immobile H2 species: "zero spin clusters (ZSC)"
• Dominant reaction at T 450 °C (annealing):
decay of ZSCs large concentration of H0
• "2-step-process" indirect way for H0 incorporation"1-step-process" direct way for H0 incorporation
Dr. Reinhart Job, University of Hagen, Germany
Formation of Extremely Deep p-n JunctionsSRP measurements:
ultra-deep p-n junc-tion in highly oxidi-zed Cz Si
[Oi] = 1.151018 cm-3
Substrate:12 cm Cz Si, [B] 11015 cm-3
(p-type)
H-Plasma:60 min at 450 °C µ-wave H-plasma (1-step-process)
0 500 1000 1500 2000103
104
105
106
107
p-typen-type
p-n junction
> 1.2 mm (!)
SR
(
cm)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Formation of Extremely Deep Graded DopingSRP measurements:
ultra-deep graded doping in highly oxidized Cz Si
[Oi] = 1.21018 cm-3
Substrate:5 cm Cz Si, [P] 11015 cm-3
(n-type)
H-Plasma:60 min at 450 °C µ-wave H-plasma (1-step-process)
0 500 1000 1500 2000103
104
105
H from the
backside
H from the
frontside
n-type Cz Si (5 cm)
SR
(
cm)
Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
Hydrogen Enhanced Thermal Donor FormationIR-absorption measurements:
verification of TDDs (neutral species up to the 5th generation)
Substrate:12 cm Cz Si, [B] 11015 cm-3
(p-type) [Oi] = 1.151018 cm-3
H-Plasma:60 min at 450 °C µ-wave H-plasma (1-step-process)
400 425 450 475 500 525 5501,5
2,0
2,5
3,0
3,5
4,0
4,5
: TDD i (i = 1 - 5)
O i
p-type
Cz Si
Abs
orpt
ion
Coe
ffici
ent (
cm-1
)
Wavenumber (cm -1)
Dr. Reinhart Job, University of Hagen, Germany
Hydrogen Enhanced Thermal Donor FormationIR-absorption measurements:
verification of TDD+s (singly ionized spe-cies up to the 5th generation)
Substrate:12 cm Cz Si, [B] 11015 cm-3
(p-type)
[Oi] = 1.151018 cm-3
H-Plasma:60 min at 450 °C µ-wave H-plasma (1-step-process)
600 700 800 900 1000 1100 1200 13000,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
: TDD i+ (i = 1 - 5) p-Typ
Cz Si?
O i
Abs
orpt
ion
Coe
ffici
ent (
cm-1
)
Wavenumber (cm -1)
Dr. Reinhart Job, University of Hagen, Germany
Hydrogen Enhanced Thermal Donor FormationIR-absorption measurements:
verification of TDDs (neutral species up to the 5th generation)
Substrate:5 cm Cz Si, [P] 11015 cm-3
(n-type)
[Oi] = 1.21018 cm-3
H-Plasma:8 h at 270 °C1 h at 450 °C µ-wave H-plasma (1-step-process)
400 420 440 460 480 500 520 540 5600
2
4
6
8
10
12
14
16
O i
b)
a)
a) H-plasma: Tpl = 270 °C, tpl = 8 h
b) H-plasma: Tpl = 450 °C, tpl = 1 h
n-Typ
Cz SiA
bsor
ptio
n C
oeffi
cien
t (cm
-1)
Wavenumber (cm -1)
Dr. Reinhart Job, University of Hagen, Germany
IR-absorption measurements:
verification of TDDs (neutral species up to the 5th generation)
Substrate:5 cm Cz Si, [P] 11015 cm-3
(n-type)
[Oi] = 1.21018 cm-3
H-Plasma:8 h at 270 °CAnnealing:1 h / 4 h at 450 °C/air(2-step-process)
Hydrogen Enhanced Thermal Donor Formation
400 420 440 460 480 500 520 540 5600
2
4
6
8
10
12
14
16Annealing:
T temp = 450 °C
b) ttemp = 1 h
c) ttemp = 4 h
O i
c)b)
a)
n-Typ
Cz Si
H-Plasma:
Tpl = 270 °C,
tpl = 8 h
a) as plasma
treatedA
bsor
ptio
n C
oeffi
cien
t (cm
-1)
Wavenumber (cm -1)
Dr. Reinhart Job, University of Hagen, Germany
Formation of Diodes by Thermal Donor Doping• Substrates:
– p-type Cz Si (1.8 - 2.6 cm , 5 - 10 cm, 12 - 20 cm)[B] 6 1014 cm-3 - 1.3 1016 cm-3 [Oi] = 7 8 1017 cm-3, [Cs] < 5 1016 cm-3
• TD formation (plasma treatment / annealing):– H-plasma: µ-wave 2.45 GHz, tpl = 30 min, Tpl = 450 °C
annealing: no annealing (1-step-process: TD-diode No. 1)
– H-plasma: 110 MHz, 50 W, tpl = 60 min, Tpl = 250 °Cannealing: tann = 20 or 30 min, Tann = 450 °C/air
(2-step-process: TD-diodes No. 2, 3)
also alternative plasma hydrogenation possible:– H-plasma: DC, 500 V, Tpl = 400 - 450 °C, tpl 30 min
(1-step-process)
Dr. Reinhart Job, University of Hagen, Germany
TD-diode (No. 1): contact area: 1 mm2 - SRP profile p-n junction depth: d = 40 µm- I(V) curves at T = RT
Substrate:12 - 20 cm Cz SiH-Plasma:30 min at 450 °C µ-wave H-plasma (1-step-process)
Formation of Diodes by Thermal Donor Doping
-100 -80 -60 -40 -20 0
0,00
0,02
0,04
0,06
0,08
0,10
I (A
)
VBIAS (V)
0 25 50 75 100 125 150104
105
106
107
n-type
region
p-type region
p-n junction
SR
(
)
Depth (m)
Dr. Reinhart Job, University of Hagen, Germany
TD-diode (No. 2): contact area: 1 cm2 - SRP profile p-n junction depth: d 170 µm- I(V) curves at T = RT
Substrate:12 - 20 cm Cz Si
H-Plasma:60 min at 250 °C Annealing:30 min 450 °C/air (2-step-process)
Formation of Diodes by Thermal Donor Doping
-100 -80 -60 -40 -20 0-0,01
0,00
0,01
0,02
0,03
0,04
I (A
)
Vbias (V)
0 50 100 150 200 250 300104
105
106
n-type region p-type region
p-n junction
SR
(
)Depth (µm)
Dr. Reinhart Job, University of Hagen, Germany
TD-diode (No. 1): contact area: 1 mm2 (1-step-process)
TD-diode (No. 2): contact area: 1 cm2 (2-step-process)
Comparison
I(V) curves at T = RT:
Data normalized to contact size !
Formation of Diodes by Thermal Donor Doping
-100 -80 -60 -40 -20 0 1 210 -5
10 -4
10 -3
10 -2
10 -1
100
101
2)2)
1)
1)
2) TD-diode (2-step-process)
1) TD-diode (1-step-process)
I (A
cm-2
)
Vbias (V)
Dr. Reinhart Job, University of Hagen, Germany
TD-diode (No. 1): contact area: 1 mm2 - I(V) curves at T = RT 150 °C
Substrate:12 - 20 cm Cz SiH-Plasma:30 min at 450 °C µ-wave H-plasma (1-step-process)
Analysis of TD-Diodes
-100 -80 -60 -40 -20 0-0,02
0,00
0,02
0,04
0,06
0,08
0,10
TD-Diode No. 1
T = 22°C, 100°C, 150°C
I (A
)
VBIAS (V)
Dr. Reinhart Job, University of Hagen, Germany
TD-diode (No. 1): contact area: 1 mm2 - C(V) measurements
linear slope C V-3 linearly graded p-n junction (if C V-2 abrupt junction)
Substrate:12 - 20 cm Cz Si
H-Plasma:30 min at 450 °C µ-wave H-plasma (1-step-process)
Analysis of TD-Diodes
-30 -25 -20 -15 -10 -5 01x10 -11
2x10 -11
3x10 -11
4x10 -11
5x10 -11
6x10 -11
f = 1 MHz "reverse bias"
VBIAS (V)
C (
F)
0,0
5,0x1031
1,0x1032
1,5x1032
2,0x1032
1/C
³ (1
/F³)
Dr. Reinhart Job, University of Hagen, Germany
TD-diode (No. 3): contact area: 1 mm2 - p-n junction depth: d 100 µm- I(V) curves, mapping at T = RT
Substrate:12 - 20 cm Cz Si
H-Plasma:60 min at 250 °C Annealing:20 min 450 °C/air (2-step-process)
Analysis of TD-Diodes / Wafer Mapping
-25 -20 -15 -10 -5 0 5-0,01
0,00
0,01
0,02
0,03
0,04
"2-step-process":
- 60 min H plasma at 260°C
- 20 min annealing at 450°C/air
waf
er ra
dius
I (A
)
Vbias (V)
Dr. Reinhart Job, University of Hagen, Germany
• appropriate plasma hydrogenation enhanced TD formation
• counter doping of p-type Cz Si can occurs due to TDs formation of deep p-n junctions (low thermal budget < 500 °C, process time 1 hour)
• graded doping in n-type Cz Si
• p-n junction formation due to TDs rapid and low thermal budget technology for high voltage or power device applications
Summary