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Advanced Topographic Resistivity Analysis Of Semi ... PDF Papers/Poster_ECSCRM2008.pdf ·...
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Outline Advanced Topographic Resistivity Analysis Of Semi-insulating SiC Substrates Wolfgang Jantz , Rudolf Stibal , Stefan Müller , Ruyue Yan and Jianmin Hao 1a 1a 1a 2b 2b 1 Semimap Scientific Instruments GmbH, Tullastr. 67, D79108 Freiburg, Germany 2 Electronic Material Research Institute of Tianjin, 26 Yanfeng Rd., Tianjin 300220, China a [email protected] b [email protected] COREMA System Basics of ntactless sistivity pping CO RE MA Capacitive probe chuck chuck wafer wafer guard guard electrode electrode 1 mm measured volume air gap 1 mm measured volume air gap 1 mm measured volume air gap Equivalent circuit Equivalent circuit t =R s (C s +C a ) Equivalent circuit U U U t =R s (C s +C a ) Charge transient after voltage step application 0 ¥ t t 0 Q Q Charge transient after voltage step application 0 ¥ t t 0 Q Q 0 ¥ t t 0 Q Q ¥ t t 0 Q Q t t 0 Q Q S.i. SiC Crystal Growth Q 0 / Q ¥ = Cs / (Cs+Ca) r = Q 0 t (Q ¥ ee 0 ) -1 Evaluation of electrical material properties Resistivity r = Q 0 t (Q ¥ ee 0 ) -1 Mobility μ = 1/B [ r(B) / r(0) - 1] ½ Activation energy E a = (kT 1 T 2 )/(T 2 -T 1 ) * ln [r(T 1 ) / r(T 2 )] R s = r d/A C s = ee 0 A/d R s C s = ree 0 d A d A Semi-insulating semiconductor Resistivity Activation Energy 2.0 2.2 2.4 2.6 2.8 3.0 3.2 10 5 10 6 10 7 10 8 10 9 10 10 10 11 Rho (Ohm*cm) 1/Temperature (1000/K) s.i. SiC Activ. Energy: 816 meV 225 200 175 150 125 100 75 50 Temperature (°C) Mobility measurement 150 mm GaAs wafer 2“ SiC wafer Temperature range 40 – 200 ° C Resistivity range 3x10 5 – 1x10 10 Ohm*cm Not semi-insulating at 300 ° C 150 mm GaAs wafer Mean: 3.96x10 7 Ohm*cm Stdv: 4.3 % Radial variation Fourfold symmetry Dislocation network The growing complexity and maturity of SiC based high frequency, high power microelectronic devices and modules continually tightens the demand on the electrical quality of semi-insulating SiC substrates. The topographic measurement system COREMA-WT and the temperature dependent measurement system COREMA-VT are used to characterize exploratory 40 mm diameter SiC wafers. We demonstrate that the combined analytic capabilities of these tools allow a very detailed assessment of the resistivity distribution across the entire wafer area. Both macroscopic variations, resulting from the growth process, as well as local intermixtures of material phases with different resistivities, resulting from incomplete compensation, are assessed with respect to absolute resistivity values and the respective volume contributions. We show that local inhomogeneity results in a temperature dependent activation energy. Resistivity Measurement Mobility Measurement Activation Energy Position B, Volume = 58% Position C, Volume = 10% Position D, Volume = 50% Position A, Volume = 100% Resistivity Topogram Volume Topogram
Transcript of Advanced Topographic Resistivity Analysis Of Semi ... PDF Papers/Poster_ECSCRM2008.pdf ·...
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Outline
Advanced Topographic Resistivity AnalysisOf Semi-insulating SiC Substrates
Wolfgang Jantz , Rudolf Stibal , Stefan Müller , Ruyue Yan and Jianmin Hao1a 1a 1a 2b 2b
1 Semimap Scientific Instruments GmbH, Tullastr. 67, D79108 Freiburg, Germany
2 Electronic Material Research Institute of Tianjin, 26 Yanfeng Rd., Tianjin 300220, China
a [email protected] b [email protected]
COREMA System
Basics of ntactlesssistivity pping
CORE MA
Capacitive probe
chuckchuck
waferwaferguardguard
electrodeelectrode
1 mm
measured
volumeair gap
1 mm
measured
volumeair gap
1 mm
measured
volumeair gap
Equivalent circuitEquivalent circuit
t = Rs(Cs+Ca)
Equivalent circuit
UUU
t = Rs (Cs+Ca)
Charge transient aftervoltage step application
0
¥
tt0
Q
Q
Charge transient aftervoltage step application
0
¥
tt0
Q
Q
0
¥
tt0
Q
Q¥
tt0
Q
Q
tt0
Q
Q
S.i. SiC Crystal Growth
Q0/ Q¥ = Cs / (Cs+Ca)
r = Q0 t (Q¥ ee0)-1
Evaluation of electrical material properties
Resistivity r = Q0 t (Q¥ e e0)-1
Mobility µ = 1/B [ r(B) / r(0) - 1] ½
Activation energy Ea = (kT1T2)/(T2-T1) * ln [r(T1) / r(T2)]
Rs = r d/A
Cs = e e0 A/d
RsCs= r e e0
dA
dA
Semi-insulating semiconductor
Resistivity
Activation Energy
2.0 2.2 2.4 2.6 2.8 3.0 3.210
5
106
107
108
109
1010
1011
Rho
(Ohm
*cm
)
1/Temperature (1000/K)
s.i. SiCActiv. Energy: 816 meV
225 200 175 150 125 100 75 50
Temperature (°C)
Mobility measurement
150 mm GaAs wafer
2“ SiC wafer
Temperature range
40 – 200°C
Resistivity range
3x105 – 1x1010 Ohm*cm
Not semi-insulating at
300°C
150 mm GaAs wafer
Mean: 3.96x107 Ohm*cm
Stdv: 4.3 %
Radial variation
Fourfold symmetry
Dislocation network
The growing complexity and maturity of SiC
based high frequency, high power
microelectronic devices and modules
continually tightens the demand on the
electrical quality of semi-insulating SiC
substrates.
The topographic measurement system
COREMA-WT and the temperature dependent
measurement system COREMA-VT are used to
characterize exploratory 40 mm diameter SiC
wafers. We demonstrate that the combined
analytic capabilities of these tools allow a very
detailed assessment of the resistivity
distribution across the entire wafer area. Both
macroscopic variations, resulting from the
growth process, as well as local intermixtures
of material phases with different resistivities,
resulting from incomplete compensation, are
assessed with respect to absolute resistivity
values and the respect ive volume
cont r ibut ions. We show that loca l
inhomogeneity results in a temperature
dependent activation energy.
Resistivity Measurement
Mobility Measurement
Activation EnergyPosition B, Volume = 58%
Position C, Volume = 10%
Position D, Volume = 50%
Position A, Volume = 100%
Resistivity Topogram
Volume Topogram
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