a 1200 v 4h-sic planar mosfet optimization for high ... · 32 kijeong han [email protected] a 1200 v...
TRANSCRIPT
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Kijeong Han
A 1200 V 4H-SiC Planar MOSFET Optimization
for High Frequency Figure-of-merit Principal Investigator: Dr. Jayant Baliga
North Carolina State University (NCSU)
v Objective
v Structure Optimization
¨ 4H-SiC Power MOSFET with improved high frequency Figure-of-merit
- Figure-of-merit (FOM) : R x C, R x Q
- Structure optimization : R ↓ è Conduction loss ↓ C, Q ↓ è Switching loss ↓
Gate
JFET
N-‐ DriR
P+ body N+ source
N+ sub Drain
Gate Source
LA
BP1 structure
Objec?ve
① JFET width ↓ + doping ↑ ② Channel length ↓ ③ P+ body contact
¨ Cell pitch ↓
Gate
N-‐ DriR
P+ body
N+ source
N+ sub Drain
Gate S
BP2 structure
JFET LA P+ body contact
Orthogonal to cross section
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FOM ↓
v Simulation Results Wcell [µm]
BV [V]
CGD,sp [nF/cm2]
QGD,sp [nC/cm2]
Ron,sp [mΩ ⋅ cm2]
FOM (= CGD x Ron) [mΩ ⋅ nF]
BP1 11 1392 0.168 355 6.75 1.134
BP1 Characteris?cs
[ Qg simulation ↑ ] [ BV simulation → ]
[ ↓ IV simulation ]
@freq. : 100 kHz
7.54 pF
@area : 4.5 mm2
7.68 pF [ ← CGD simulation
& CGD measurement ]
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v Simulation Results
§ LA : 1.7 µm (BP1) § LA : 0.7 µm
< E-field (BV = 1392 V) > < E-field (BV = 1620 V) >
@Limit of Oxide Field : 4 MV/cm
@JFET doping : 8x1015 cm-3
JFET Op?miza?on (1/2)
< Current flow (Ron,sp = 6.75 mΩ⋅cm2) > < Current flow (Ron,sp = 10.84 mΩ⋅cm2) > 35
: FOM
@freq. : 100 kHz
: Cgd,sp
: Ron,sp
JFET doping (cm-3)
LA (µm)
BV (V)
Ron,sp (mΩ-cm2)
Cgd,sp (pF/cm2)
FOM (Ron,sp x Cgd,sp) (mΩ-pF)
~4e16
0.7 1614 4.55 81.46 370.6 (x 3) 1 1526 4.04 113.92 460.2
1.5 1192 4.06 155.84 632.7 2 988 4.17 208.9 871.1
2.5 875 4.31 254.29 1096.0 3 808 4.43 293.72 1301.2
@VDrain : 1000 V
: BV
JFET Op?miza?on (2/2)
Cgd,sp simulation
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v Summary of Characteristics
Wcell [µm]
BV [V]
CGD,sp [nF/cm2]
QGD,sp [nC/cm2]
Ron,sp [mΩ⋅cm2]
FOM (= CGD x Ron)
[mΩ ⋅ nF]
FOM (= QGD x Ron)
[mΩ ⋅ nC]
BP1 11 1392 0.168 355 6.75 1.134 2398
BP2 5.6 1613 0.0928 233 3.47 0.322 (x3.52) 808.86 (x2.96)
Figure-‐Of-‐Merit (FOM)
BP1 structure
① JFET width ↓ + doping ↑
② Channel length ↓
③ P+ body contact
BP2 structure
§ NJFET : 0.8e16 cm-3 § LA : 1.7 µm § LCH : 0.8 µm § Wcell : 11 µm
§ NJFET : ~4e16 cm-3 § LA : 0.7 µm § LCH : 0.5 µm § Wcell : 5.6 µm
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