CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Accurate Physical Model for the Lateral IGBT in Silicon On Insulator Technology Ettore Napoli 1,2, Vasantha Pathirana 1, Florin Udrea 1,3 1 Dept. of Engineering, University of Cambridge, UK 2 Dept. Electronic and Telecom. Univ. of Napoli, Italy 3 Cambridge Semiconductor (CamSemi), UK EU research program ROBUSPIC

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Outline  Motivation  Thin SOI LIGBT  Differences with Vertical IGBT  Spice sub-circuit model for LIGBT  Model equations  Model behavior  Numerical results  Conclusion

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Motivation Available IGBT circuit models are not suited to Lateral IGBT Need for –a reliable physical based model for Lateral IGBT –usable in various circuit simulators Extension to different LIGBT technologies Important for smart power design

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Thin SOI Lateral IGBT 600V PT Transparent buffer Source and Drain up to the BOX Current flow is horizontal and 1D

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (1) Not zero carrier concentration at the collector edge for LIGBT

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (2) Electrons injected from the n+ accumulation layer into the n- drift across the n+/n- junction. The structure features double injection (similar to a PIN or a thyristor)

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Total charge and charge profile LIGBT Vertical IGBT Differences with Vertical IGBT (3)

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (4) Depletion width vs. reverse voltage is influenced by 2D effects

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (5) Depletion width LIGBT vs. Vertical IGBT 0V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (5) Depletion width LIGBT vs. Vertical IGBT 5V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (5) Depletion width LIGBT vs. Vertical IGBT 10V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (5) Depletion width LIGBT vs. Vertical IGBT 100V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (5) Depletion width LIGBT vs. Vertical IGBT 200V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (5) Depletion width LIGBT vs. Vertical IGBT 300V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Differences with Vertical IGBT (6) Depletion region mobile charge effect

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 IGBT models not suited for LIGBT Voltage rise at turn-off is faster due to lower charge in the epilayer and slower depletion width expansion

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Spice sub-circuit model for LIGBT Currents and voltages Epilayer charge equation

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Spice sub-circuit model for LIGBT Vj :Emitter junction Vdrift:Depends on the injected carriers –analytic solution Vmos:Mosfet (level 1)

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Spice sub-circuit model for LIGBT I N (W) : Electron current through the level 1 Mosfet

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Spice sub-circuit model for LIGBT I P (W) : Bipolar hole current

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Spice sub-circuit model for LIGBT I N (0) : Electron current through the emitter junction

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Spice sub-circuit model for LIGBT I PC_TRN :Transient current due to charge sweep-out Increasing Anode Voltage Stable Anode Voltage P0P0 PWPW WtWt W t+δt W t+2δ t Time is increasing 0

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Base charge equation  I N (W) is the MOSFET current  I N (0) is the emitter edge electron current  I PC_TRN is the charge sweep out current  The last term is for the recombination in the base

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Other model features  Carrier concentration dependent mobility model  Gate-Source Drain-Source and Gate-Drain capacitances are implemented  Physical based model with 17 parameters

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 NameMeaningUnit Vth Threshold voltageV Nb Drift dopingcm^-3 Wb Drift region length (51e-4)cm Wnw N well lengthcm Wfp Field plate extensioncm un Electron mobilitycm^2/Vs up Hole mobilitycm^2/Vs A Device transversal areacm^2 Kp Mos transconductanceA/V^2 NameMeaningUnit Isne P+ emitter inverse saturation current A Cbcj Body Drift region depletion capacitance factor F/cm^2 Cox oxide Gate Drain capacitanceF/cm^2 Cgs gate source capacitanceF/cm^2 Taub drift region ambipolar lifetime (0.35e-6) s pw_ratio P(0)/P(W) W_inc Depletion width expansion factor V_fp Field plate depletion voltageV Spice circuit parameters

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Static characteristics

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Model behavior Inductive Turn-off Expanded for I=1A, V=200V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 V=200V, I=2A. V=400V, I=2A. Transient behavior

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Resistive switch, 200  resistor load Transient behavior

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Model behavior Toff Energy vs. Von as a function of lifetime

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISIE, Dubrovnik, June 21st 2005 Conclusion A physical based circuit model for Lateral IGBT Implemented in Spice Defined through 17 physical parameters Compared against device numerical simulation Extendable to Thick SOI and JI-LIGBT