A compact model for thin SOI LIGBTs:

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A compact model for thin SOI LIGBTs description,
experimental verification and system
application Ettore Napoli1,2, Vasantha
Pathirana1, Florin Udrea1,3,Guillaumme
Bonnet3,Tanja Trajkovic3,Gehan Amaratunga3 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
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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

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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

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Thin SOI Lateral IGBT

• 600V PT
• Transparent buffer
• Source and Drain up to the BOX
• Current flow is horizontal and 1D

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Differences with Vertical IGBT (1)

• Not zero carrier concentration at the collector
  edge for LIGBT

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IGBT models not suited for LIGBT (1)

• Total charge and charge profile
• LIGBT
• Vertical IGBT

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Differences with Vertical IGBT (2)

• Depletion width vs. reverse voltage is influenced
  by 2D effects

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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

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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

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Spice sub-circuit model for LIGBT
Currents and voltages Epilayer
charge equation
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Spice sub-circuit model for LIGBT

• Vj Emitter junction
• Vdrift Depends on the injected carriers
• analytic solution
• Vmos Mosfet (level 1)

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Spice sub-circuit model for LIGBT

• IN(W) Electron current through the level 1
  Mosfet

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Spice sub-circuit model for LIGBT

• IP(W) Bipolar hole current

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Spice sub-circuit model for LIGBT

• IN(0) Electron current through the emitter
  junction

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Spice sub-circuit model for LIGBT

• IPC_TRN Transient current due to charge
  sweep-out

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Base charge equation

• IN(W) is the MOSFET current
• IN(0) is the emitter edge electron current
• IPC_TRN is the charge sweep out current
• The last term is for the recombination in the
  base

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Other model features

• Carrier concentration dependent mobility model
• Gate-Source Drain-Source and Gate-Drain
  capacitances are implemented
• Physical based model with 13 parameters

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Model behavior
Expanded for I1A, V200V
Inductive Turn-off
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Model behavior

• Toff Energy vs. Von as a function of lifetime

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Half bridge circuit

• Output characteristics
• 200V 2A 100kHz

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Experimental results on flyback circuit
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Experimental results on flyback circuit
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Flyback circuit simulation

• Complete flyback circuit
• The simulated waveforms are for the primary
  winding voltage (green) and the load voltage
  (red)

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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