CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 A compact model for thin SOI LIGBTs: description, experimental verification and system application Ettore Napoli 1,2, Vasantha Pathirana 1, Florin Udrea 1,3, Guillaumme Bonnet 3,Tanja Trajkovic 3,Gehan Amaratunga 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 ISPSD, Santa Barbara, May 2005 Outline  Motivation  Thin SOI LIGBT  Differences with Vertical IGBT  Spice sub-circuit model for LIGBT  Model equations  Model behavior  Half bridge circuit using lateral IGBT  Experimental results on flyback circuit  Conclusion

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 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 ISPSD, Santa Barbara, May 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 ISPSD, Santa Barbara, May 2005 Differences with Vertical IGBT (1) Not zero carrier concentration at the collector edge for LIGBT

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 IGBT models not suited for LIGBT (1) Total charge and charge profile LIGBT Vertical IGBT

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Differences with Vertical IGBT (2) Depletion width vs. reverse voltage is influenced by 2D effects

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 IGBT models not suited for LIGBT (2) Voltage rise at turn-off is faster due to lower charge in the epilayer and slower depletion width expansion

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 IGBT models not suited for LIGBT (3) Important effects such as the voltage bump, resulting in a delay in the turn-off, are not considered

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Spice sub-circuit model for LIGBT Currents and voltages Epilayer charge equation

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 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 ISPSD, Santa Barbara, May 2005 Spice sub-circuit model for LIGBT I N (W) : Electron current through the level 1 Mosfet

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Spice sub-circuit model for LIGBT I P (W) : Bipolar hole current

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Spice sub-circuit model for LIGBT I N (0) : Electron current through the emitter junction

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 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 ISPSD, Santa Barbara, May 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 ISPSD, Santa Barbara, May 2005 Other model features  Carrier concentration dependent mobility model  Gate-Source Drain-Source and Gate-Drain capacitances are implemented  Physical based model with 13 parameters

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Model behavior Inductive Turn-off Expanded for I=1A, V=200V

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Model behavior Toff Energy vs. Von as a function of lifetime

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Half bridge circuit Output characteristics 200V; 2A; 100kHz

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Experimental results on flyback circuit

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Experimental results on flyback circuit

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Flyback circuit simulation Complete flyback circuit The simulated waveforms are for the primary winding voltage (green) and the load voltage (red)

CAMBRIDGE UNIVERSITY NAPOLI UNIVERSITY ISPSD, Santa Barbara, May 2005 Conclusion A physical based circuit model for Lateral IGBT Implemented in Spice Compared against –Device numerical simulation –Complex SMPS simulation –Experimental results Extendable to Thick SOI and JI-LIGBT