Thèse de doctorat
Soutenue publiquement le 26 novembre 2010
Etude de la conduction électrique dans les diélectriques à forte permittivité utilisés en
microélectronique
Jean Coignus
Directeur de thèse : M. Raphaël CLERC IMEP-LAHC
Co-encadrant :
M. Charles LEROUX CEA-LETI Minatec
Fundamental limits of SiO
2thickness downscaling
• Conventional bulk MOSFET scaling
Source Drain
Gate
Source Drain
tSiO2 Gate
tSiO2
Lg Lg
Fundamental limits of SiO
2thickness downscaling
• Conventional bulk MOSFET scaling
Source Drain
Gate
Source Drain
Gate
Ion
tSiO2
tSiO2
Ion
Ion ↑↑ ☺☺☺☺
Lg Ig ↑↑ Lg
Fundamental limits of SiO
2thickness downscaling
• Conventional bulk MOSFET scaling
• High-κ dielectrics : mandatory for HP 45nm node and beyond
© Intel corp. ’07
Source Drain
Gate
Source Drain
Gate
Ion
tSiO2
tSiO2
Ion
Ion ↑↑ ☺☺☺☺
Lg Ig ↑↑ Lg
Fundamental limits of SiO
2thickness downscaling
• Conventional bulk MOSFET scaling
• High-κ dielectrics : mandatory for HP 45nm node and beyond
© Intel corp. ’07
Source Drain
Gate
Source Drain
Gate
Ion
tSiO2
tSiO2
Ion
Ion ↑↑ ☺☺☺☺
Lg Ig ↑↑ Lg
Basics :
higher permittivity = higher tphys @constant Cox
MG High-κ PolySi
SiO2
High-κ dielectrics integration
• What about effective leakage reduction ?
High-κ dielectrics integration
• What about effective leakage reduction ?
– Dielectric parameters
Ig strongly correlated to m / Φ : high-κ dielectrics appear more conductive
0 10 20 30 40 50 60 70
2 3 4 5 6 7 8 9 10
TiO2 HfTiTaO HfBiON
HfTiON La2O3 Ta2O5
ZrO2 HfO2 Y2O3
Si3N4SrO ZrSiO4 HfSiO4
CaO MgO
Al2O3 SiO2
Band Gap [eV]
Relative Permittivity
Huang VLSI ’09
Silicon Gate
tox
Φox mox
High-κ dielectrics integration
• What about effective leakage reduction ?
– Dielectric parameters
Ig strongly correlated to m / Φ : high-κ dielectrics appear more conductive
– Transport mechanisms
SiO2 Direct Tunneling
high-κ Presence of Trap-Assisted mechanisms ?
0 10 20 30 40 50 60 70
2 3 4 5 6 7 8 9 10
TiO2 HfTiTaO HfBiON
HfTiON La2O3 Ta2O5
ZrO2 HfO2 Y2O3
Si3N4SrO ZrSiO4 HfSiO4
CaO MgO
Al2O3 SiO2
Band Gap [eV]
Relative Permittivity
Huang VLSI ’09
Silicon Gate
tox
Φox mox
High-κ dielectrics integration
• What about effective leakage reduction ?
– Dielectric parameters
Ig strongly correlated to m / Φ : high-κ dielectrics appear more conductive
– Transport mechanisms
SiO2 Direct Tunneling
high-κ Presence of Trap-Assisted mechanisms ?
– Integration limitations (HfO2 case) : presence of an Interfacial Layer
0 10 20 30 40 50 60 70
2 3 4 5 6 7 8 9 10
TiO2 HfTiTaO HfBiON
HfTiON La2O3 Ta2O5
ZrO2 HfO2 Y2O3
Si3N4SrO ZrSiO4 HfSiO4
CaO MgO
Al2O3 SiO2
Band Gap [eV]
Relative Permittivity
Huang VLSI ’09
Silicon Gate
tox
Φox mox
State of the art
• Gate leakage current modeling has already been studied
[Lo EDL ‘97, Li TED ‘06, Palestri TED ‘07…]
State of the art
• Gate leakage current modeling has already been studied
[Lo EDL ‘97, Li TED ‘06, Palestri TED ‘07…]
• However, this topic remains controversial
– Ig @300K
• Direct Tunneling ?
[Hou EDL ‘03, Govoreanu SSE ‘04]
• Additional transport mechanisms ?
[Xu APL 2002, Blank JAP 2005, Houssa JAP 2000]
– Interfacial Layer may differ from pure SiO2
[Damlencourt SSE ’03]
– Effective Mass Approximation in high-κ ?
[Sacconi TED ’09]
State of the art
• Gate leakage current modeling has already been studied
[Lo EDL ‘97, Li TED ‘06, Palestri TED ‘07…]
• However, this topic remains controversial
– Ig @300K
• Direct Tunneling ?
[Hou EDL ‘03, Govoreanu SSE ‘04]
• Additional transport mechanisms ?
[Xu APL 2002, Blank JAP 2005, Houssa JAP 2000]
– Interfacial Layer may differ from pure SiO2
[Damlencourt SSE ’03]
– Effective Mass Approximation in high-κ ?
[Sacconi TED ’09] 0,00,0 0,1 0,2 0,3 0,4
0,5 1,0 1,5 2,0 2,5 3,0
[11]
[9] [10]
[8]
[7]
[5] [6]
[4]
[3]
[2]
[1]
Si-HfO 2 Cond. Band Offset [eV]
Electron Tunneling Mass in HfO2 [units of m0]
[1] Palestri TED 2007, [2-3] Kar TED 2005, [4] Buckley ESSDERC 2005, [5] Zhu EDL 2002, [6] Govoreanu SSE 2003, [7] Zhao SSE 2004, [8] Wu SSE 2006, [9] Campera TED 2007, [10] Hou EDL 2003, [11] Garros PhD 2004
Lack of complete experimental studies
me,HfO2[units of m0] Φe,HfO2[eV]
State of the art
• Gate leakage current modeling has already been studied
[Lo EDL ‘97, Li TED ‘06, Palestri TED ‘07…]
• However, this topic remains controversial
– Ig @300K
• Direct Tunneling ?
[Hou EDL ‘03, Govoreanu SSE ‘04]
• Additional transport mechanisms ?
[Xu APL 2002, Blank JAP 2005, Houssa JAP 2000]
– Interfacial Layer may differ from pure SiO2
[Damlencourt SSE ’03]
– Effective Mass Approximation in high-κ ?
[Sacconi TED ’09] 0,00,0 0,1 0,2 0,3 0,4
0,5 1,0 1,5 2,0 2,5 3,0
[11]
[9] [10]
[8]
[7]
[5] [6]
[4]
[3]
[2]
[1]
Si-HfO 2 Cond. Band Offset [eV]
Electron Tunneling Mass in HfO2 [units of m0]
[1] Palestri TED 2007, [2-3] Kar TED 2005, [4] Buckley ESSDERC 2005, [5] Zhu EDL 2002, [6] Govoreanu SSE 2003, [7] Zhao SSE 2004, [8] Wu SSE 2006, [9] Campera TED 2007, [10] Hou EDL 2003, [11] Garros PhD 2004
Aim of this work :
Re-investigate transport mechanisms in high-κ gate stacks by mean of a complete experimental study performed :
- at low temperature (transport mechanisms)
- on various HKGS showing thickness variants (IL nature investigation, EMA validity)
Φe,HfO2[eV]
me,HfO2[units of m0]
Outline
• Tunneling current modeling
– Self-consistent Poisson-Schrödinger simulation – Transmission probability
• Experimental investigation of leakage current in HfO2 gate stacks
– Transport mechanisms
– Dielectric thicknesses extraction – Tunneling parameters extraction
– Dipole effect in Mg-capped HfO2 gate stacks
• Conclusions
Outline
• Tunneling current modeling
– Self-consistent Poisson-Schrödinger simulation – Transmission probability
• Experimental investigation of leakage current in HfO2 gate stacks
– Transport mechanisms
– Dielectric thicknesses extraction – Tunneling parameters extraction
– Dipole effect in Mg-capped HfO2 gate stacks
• Conclusions
Tunneling current modeling
Silicon substrate
IL
high-κ
metal gate
-2 -1 0 1 2
10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4
8Å IL - 20Å HfO2 - TiN
Gate current Ig [A.m-2 ]
Gate bias Vg [V]
nMOS
Tunneling current modeling
Silicon substrate
IL
high-κ
metal gate
Silicon substrate
IL
high-κ metal gate
-2 -1 0 1 2
10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4
8Å IL - 20Å HfO2 - TiN
Gate current Ig [A.m-2 ]
Gate bias Vg [V]
nMOS
Tunneling current modeling
• Tunneling current from 2D gas :
I
g= Σ Q
i(E
i) . f
i(E
i) . T
i(E
i)
Silicon substrate
IL
high-κ
metal gate
Silicon substrate
IL
high-κ metal gate
-2 -1 0 1 2
10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4
8Å IL - 20Å HfO2 - TiN
Gate current Ig [A.m-2 ]
Gate bias Vg [V]
i
nMOS
Tunneling current modeling
• Tunneling current from 2D gas :
I
g= Σ Q
i(E
i) . f
i(E
i) . T
i(E
i)
1. Qi(Vg) and Ei(Vg) : Poisson-Schrödinger simulation
Silicon substrate
IL
high-κ
metal gate
Silicon substrate
IL
high-κ metal gate
-2 -1 0 1 2
10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4
8Å IL - 20Å HfO2 - TiN
Gate current Ig [A.m-2 ]
Gate bias Vg [V]
i
nMOS
Tunneling current modeling
• Tunneling current from 2D gas :
I
g= Σ Q
i(E
i) . f
i(E
i) . T
i(E
i)
1. Qi(Vg) and Ei(Vg) : Poisson-Schrödinger simulation 2. Ti(Ei) : transmission probability modeling
= fct ( mIL / ΦIL / mhigh-κ / Φhigh-κ )
Silicon substrate
IL
high-κ
metal gate
Silicon substrate
IL
high-κ metal gate
-2 -1 0 1 2
10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4
8Å IL - 20Å HfO2 - TiN
Gate current Ig [A.m-2 ]
Gate bias Vg [V]
i
nMOS
Outline
• Tunneling current modeling
– Self-consistent Poisson-Schrödinger simulation – Transmission probability
• Experimental investigation of leakage current in HfO2 gate stacks
– Transport mechanisms
– Dielectric thicknesses extraction – Tunneling parameters extraction
– Dipole effect in Mg-capped HfO2 gate stacks
• Conclusions
Poisson-Schrödinger simulation
• Principle
Schrödinger equation
Poisson equation Charge
ρi(z)
Potential Vi(z) Potential
Vi-1(z)
|Vi-Vi-1| < ε? YES NO
0 2 4 6 8 10
0 1 2 3
0 1x107 2x107 3x107 4x107
Energy [eV]
Position [nm]
Si IL
HfO2
Charge [C.m -3] eg. : nMOS, 0.8nm IL – 2nm HfO2@Vg = 3V
Poisson-Schrödinger simulation
• Principle
• Dedicated to…
– … gate current modeling
Schrödinger equation
Poisson equation Charge
ρi(z)
Potential Vi(z) Potential
Vi-1(z)
|Vi-Vi-1| < ε? YES NO
0 2 4 6 8 10
0 1 2 3
0 1x107 2x107 3x107 4x107
Energy [eV]
Position [nm]
Si IL
HfO2
Charge [C.m -3] eg. : nMOS, 0.8nm IL – 2nm HfO2@Vg = 3V
Poisson-Schrödinger simulation
• Principle
• Dedicated to…
– … gate current modeling
– … parameter extraction from C(Vg) measurements
Schrödinger equation
Poisson equation Charge
ρi(z)
Potential Vi(z) Potential
Vi-1(z)
|Vi-Vi-1| < ε? YES NO
0 2 4 6 8 10
0 1 2 3
0 1x107 2x107 3x107 4x107
Energy [eV]
Position [nm]
Si IL
HfO2
Charge [C.m -3]
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 0.000
0.005 0.010 0.015 0.020 0.025
EOT = 1.16nm VFB = -0.35V Na = 2.1023m-3
Experiment PS simulation
Gate capacitance [F.m-2 ]
Gate bias Vg [V]
eg. : nMOS, 0.8nm IL – 2nm HfO2@Vg = 3V
Poisson-Schrödinger simulation
• Main features
– 1D simulation with closed boundaries
Poisson-Schrödinger simulation
• Main features
– 1D simulation with closed boundaries
– Simulation of dielectrics + whole substrate
high-κ
Quantum box
(Schrödinger equation) Classic
ρ(z)
20nm
IL
0 5 10 15 20 25 30
0 1 2 3 4 5 6 7 8 9 10
101 102 103 104 105 106 107 108 109
Energy [eV]
Position [nm]
quantum / classical treatment connection
VS = 0,7 eV
quantum box limit
ρe(z) (quantum)
ρe(z) (classical) Charge [C.m] -3
Poisson-Schrödinger simulation
• Main features
– 1D simulation with closed boundaries
– Simulation of dielectrics + whole substrate – Newton-Raphson convergence procedure
high-κ
Quantum box
(Schrödinger equation) Classic
ρ(z)
20nm
IL
0 5 10 15 20 25 30
0 1 2 3 4 5 6 7 8 9 10
101 102 103 104 105 106 107 108 109
Energy [eV]
Position [nm]
quantum / classical treatment connection
VS = 0,7 eV
quantum box limit
ρe(z) (quantum)
ρe(z) (classical) Charge [C.m] -3
Poisson-Schrödinger simulation
• Main features
– 1D simulation with closed boundaries
– Simulation of dielectrics + whole substrate – Newton-Raphson convergence procedure – Non-uniform mesh
high-κ
Quantum box
(Schrödinger equation) Classic
ρ(z)
20nm
IL
0 5 10 15 20 25 30
0 1 2 3 4 5 6 7 8 9 10
101 102 103 104 105 106 107 108 109
Energy [eV]
Position [nm]
quantum / classical treatment connection
VS = 0,7 eV
quantum box limit
ρe(z) (quantum)
ρe(z) (classical) Charge [C.m] -3
Poisson-Schrödinger simulation
• Main features
– 1D simulation with closed boundaries
– Simulation of dielectrics + whole substrate – Newton-Raphson convergence procedure – Non-uniform mesh
– Electrons + holes both considered
high-κ
Quantum box
(Schrödinger equation) Classic
ρ(z)
20nm
IL
0 5 10 15 20 25 30
0 1 2 3 4 5 6 7 8 9 10
101 102 103 104 105 106 107 108 109
Energy [eV]
Position [nm]
quantum / classical treatment connection
VS = 0,7 eV
quantum box limit
ρe(z) (quantum)
ρe(z) (classical) Charge [C.m] -3
0 25 50 75 100 125 150
0.0 0.4 0.8 1.2 1.6 2.0
0 1x104 2x104 3x104 4x104
Energy [eV]
Position [nm]
Depletion profile Approximated
profile Charge [C.m] -3
Poisson-Schrödinger simulation : WFP
• Conventional PS resolution : simulation of Silicon substrate only
-2 -1 0 1 2 3 4 5
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0 1 2 3 4
Energy [eV]
Position [nm]
without WFP
Wavefunction L0 [u.a.]
Vg= 2V
Poisson-Schrödinger simulation : WFP
• Conventional PS resolution : simulation of Silicon substrate only
• This work : Silicon substrate + gate dielectrics both included
-2 -1 0 1 2 3 4 5
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0 1 2 3 4
Energy [eV]
Position [nm]
high-κ IL
with WFP without WFP
Wavefunction L0 [u.a.]
Vg= 2V
Poisson-Schrödinger simulation : WFP
• Conventional PS resolution : simulation of Silicon substrate only
• This work : Silicon substrate + gate dielectrics both included
Without WFP : 1Å error in EOT extraction
-2 -1 0 1 2 3 4 5
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
0 1 2 3 4
Energy [eV]
Position [nm]
high-κ IL
with WFP without WFP
Wavefunction L0 [u.a.]
-4 -3 -2 -1 0 1 2 3
0.000 0.005 0.010 0.015 0.020 0.025 0.030
Simulation with WFP
without WFP
Cox = εSiO2 / EOT
Gate capacitance [F.m-2 ]
Gate bias Vg [V]
EOT = 1.23nm Vg= 2V nMOS
Poisson-Schrödinger simulation : VB description
• Conduction band description : Effective Mass Approximation OK
Poisson-Schrödinger simulation : VB description
• Conduction band description : Effective Mass Approximation OK
• Holes description : bands centered around k=0
degeneracy anisotropy
non-parabolicity
k
E
(split-off band)
∆0 EHH(k) ELH(k)
ESO(k)
HH LH [Guillaume PhD ’05]
Poisson-Schrödinger simulation : VB description
• Conduction band description : Effective Mass Approximation OK
• Holes description : bands centered around k=0
degeneracy anisotropy
non-parabolicity
k
E
(split-off band)
∆0 EHH(k) ELH(k)
ESO(k)
HH LH [Guillaume PhD ’05]
VB non-parabolicity
integrated in PS simulation
Poisson-Schrödinger simulation : VB description
• Conduction band description : Effective Mass Approximation OK
• Holes description : bands centered around k=0
degeneracy anisotropy
non-parabolicity
• Main idea: advanced 2D-holes description using analytical E-k fitted on 6x6 k.p results
[DeMichielis et al., IEEE TED 54, 2008]
Analytical 2D-holes Density-of-States
k
E
(split-off band)
∆0 EHH(k) ELH(k)
ESO(k)
HH LH [Guillaume PhD ’05]
VB non-parabolicity
integrated in PS simulation
Poisson-Schrödinger simulation : VB description
• Impact on EOT extraction ?
-0.02 -0.01 0.00 0.01 0.02 0.03
0.1 0.2 0.3 0.4 0.5 0.6 0.7
WFP WFP
Effective Mass Approximation Advanced VB description
accumulation inversion
Darkspace [nm]
Charge [C.m-2]
13% difference
nMOS
Coignus et al., SISC ’09
Poisson-Schrödinger simulation : VB description
• Impact on EOT extraction ?
-0.02 -0.01 0.00 0.01 0.02 0.03
0.1 0.2 0.3 0.4 0.5 0.6 0.7
WFP WFP
Effective Mass Approximation Advanced VB description
accumulation inversion
Darkspace [nm]
Charge [C.m-2]
5% difference
nMOS
Coignus et al., SISC ’09
Poisson-Schrödinger simulation : VB description
• Impact on EOT extraction ?
This advanced approach does not significantly impact EOT extraction
-0.02 -0.01 0.00 0.01 0.02 0.03
0.1 0.2 0.3 0.4 0.5 0.6 0.7
WFP WFP
Effective Mass Approximation Advanced VB description
accumulation inversion
Darkspace [nm]
Charge [C.m-2]
nMOS
Coignus et al., SISC ’09
Outline
• Tunneling current modeling
– Self-consistent Poisson-Schrödinger simulation – Transmission probability
• Experimental investigation of leakage current in HfO2 gate stacks
– Transport mechanisms
– Dielectric thicknesses extraction – Tunneling parameters extraction
– Dipole effect in Mg-capped HfO2 gate stacks
• Conclusions
Transmission probability modeling
• Transmission probability parameters :
• Several approaches in literature, differing by their accuracy and nature (analytical or numerical)
p-Silicon
Metal High-κ IL BC
thigh-k tIL
ΦIL Φhigh-k
me,IL me,high-k
Vg = VFB
p-Silicon High-κ IL
BC
Vox,IL
Vg > VFB
E [eV]
0
Vox,high-k
Transmission probability modeling
• Airy formalism [Allen JAP ’96]
– Exact solution of Schrödinger equation in a triangular barrier
– Solving wavefunction continuity at each triangular barrier transition provides T
↑↑ exact solution
↓↓ use of Airy function, inadequate to standard compact model libraries
√ x
Airy formalism
« Exact » solution Analytical
approach ?
IL high-κ
0 1 2 3
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
Airy
Transmission probability
E
0
Transmission probability modeling
√ x WKB
√ x
Airy formalism
« Exact » solution Analytical
approach ?
IL high-κ
0 1 2 3
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
Airy WKB
Transmission probability
Energy [eV]
• WKB (1926)
– Analytical method
– Valid only for smoothly varying potential barriers
↑↑ analytical approach
↓↓ poor accuracy (reflections on potential discontinuities at interfaces not included)
eg. : 0.8nm SiO2– 2nm HfO
E
0
Transmission probability modeling
• Transfer matrix [Ando JAP ’87]
– Computational method: discretization
of an arbitrary barrier by N square barriers – Solving wavefunction continuity at each
square barrier transition provides T
↑↑ accuracy (N > 20)
↓↓ numerical approach, computational time
≈ x
Transfer matrix
√ x WKB
√ x
Airy formalism
« Exact » solution Analytical
approach ?
IL high-κ
0 1 2 3
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
Airy WKB
Transfer matrix Advanced WKB
Transmission probability
E
0
Transmission probability modeling
• Advanced WKB
– Extended from WKB analytical formula – Provides multiplicative factor correcting for
potential discontinuities
↑↑ analytical approach
↑↑ accuracy
↓↓ validity : Direct Tunneling only
≈ x
Transfer matrix
√ ≈ Advanced WKB
√ x WKB
√ x
Airy formalism
« Exact » solution Analytical
approach ?
IL high-κ
0 1 2 3
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
Airy WKB
Transfer matrix Advanced WKB
Transmission probability
Energy [eV]
eg. : 0.8nm SiO2– 2nm HfO
E
0
Transmission probability modeling
• Effective barrier height approximation
– Exact solution of Schrödinger equation in a squares barriers
– Solving wavefunction continuity at each triangular barrier transition provides T
↑↑ analytical approach
↑↑ accuracy in DT regime
↓↓ may lead to important error around TD – FN transitions
≈ x
Transfer matrix
√ x WKB
√ ≈ Effective barrier
√ ≈ Advanced WKB
√ x
Airy formalism
« Exact » solution Analytical
approach ?
IL high-κ
0 1 2 3
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101
Airy WKB
Transfer matrix Advanced WKB Effective barrier
Transmission probability
E
0 Coignus et al., JVST B ’09
Outline
• Tunneling current modeling
– Self-consistent Poisson-Schrödinger simulation – Transmission probability
• Experimental investigation of leakage current in HfO2 gate stacks
– Transport mechanisms
– Dielectric thicknesses extraction – Tunneling parameters extraction
– Dipole effect in Mg-capped HfO2 gate stacks
• Conclusions
Gate leakage mecanisms in HfO
2gate stacks
metal
high-κ
p-type Silicon
e-
Gate leakage mecanisms in HfO
2gate stacks
metal
high-κ
p-type Silicon
e-
TAT / PF (αT)
Gate leakage mecanisms in HfO
2gate stacks
metal
high-κ
p-type Silicon
e- IL and high-k properties : unknown
(m, ε, Φ, tox)
TAT / PF (αT)
Gate leakage mecanisms in HfO
2gate stacks
• Issue 1 : Identification of transport mechanisms
current assisted
trap e temperatur current
tunneling direct
total
J J
J = +
/Depends on T only via Qsc(T)
Qsc(T) dependant + temperature assisted metal
high-κ
p-type Silicon
e- IL and high-k properties : unknown
(m, ε, Φ, tox)
TAT / PF (αT)
Gate leakage mecanisms in HfO
2gate stacks
• Issue 1 : Identification of transport mechanisms
current assisted
trap e temperatur current
tunneling direct
total
J J
J = +
/Depends on T only via Qsc(T)
Qsc(T) dependant + temperature assisted
low / high temperature measurements at constant Qsc (i.e. field)
metal
high-κ
p-type Silicon
e- IL and high-k properties : unknown
(m, ε, Φ, tox)
TAT / PF (αT)
Transport mechanisms : methodology
1. Several nMOS transistors tested
– p Silicon / RTO SiO2 / n+ Polysilicon (ref. samples)
tSiO2 = 1.5 / 2.5 nm
Poly Si SiO2
p-Si
Poly Si SiO2
p-Si
Transport mechanisms : methodology
1. Several nMOS transistors tested
– p Silicon / RTO SiO2 / n+ Polysilicon (ref. samples)
tSiO2 = 1.5 / 2.5 nm
– p Silicon / IL / ALD HfO2 / CVD TiN
Poly Si SiO2
p-Si
Poly Si SiO2
p-Si
TiN HfO2
IL
p-Si
TiN HfO2
IL p-Si
TiN HfO2
IL p-Si
tIL (RTO) = 1.2 / 1.5 / 2.0 nm tHfO2 = cte = 3 nm
