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					  Power Device Compact Modelling


                         Phil Mawby
                University of Wales Swansea




University of
Wales                MOS-AK meeting, Leuven, September 2004
                               Outline
 Thermal Compact Models
 Electrical Compact Models
           MOSFET
           PiN Diode
           NPTIGBT
           PTIGBT
 Model Validation Examples




University of
Wales                   MOS-AK meeting, Leuven, September 2004
Physically Based Electro-Thermal
Compact Modelling Approach




   ET compact models of the
    semiconductor devices as
    a connection between
    electrical and thermal
    networks



University of
Wales              MOS-AK meeting, Leuven, September 2004
Electro-Thermal Modelling Strategy


   Structure
   diagram of the
   ET compact
   model




University of
Wales               MOS-AK meeting, Leuven, September 2004
Thermal Compact Models – Thermal Networks
                 Static Thermal Network                      Dynamic Thermal Network

                        Rth
                 Tj

                       Pdiss
                  j= a
                 T T + RthPdiss                                        Foster’s network


                               Rth1

                                     Rth2
                         Tj
                                                                       Cauer’s network
                      Rth3
                  Star-shaped resistance
                  network


 University of
 Wales                        MOS-AK meeting, Leuven, September 2004
Extraction of the RC Thermal Network Parameters:
Thermal Transient Response Function




University of
Wales           MOS-AK meeting, Leuven, September 2004
  Extraction of the RC Thermal Network Parameters:
  Thermal Transient Response Function



First step is to obtain thermal
transient response function of
the device for a step function
excitation.




   University of
   Wales                          MOS-AK meeting, Leuven, September 2004
Extraction of the RC Thermal Network Parameters:
Thermal Transient Response Function




3D FEM prediction of the
SML5020BN device temperature
distribution after t=1000s




 University of
 Wales                  MOS-AK meeting, Leuven, September 2004
Extraction of the RC Thermal Network Parameters:
Thermal Transient Response Function
                                           SML5020 Internal Diode
                                           Temperature Characterisation

                                     600


                                     550


                Diode Voltage [mV]   500


                                     450


                                     400


                                     350


                                     300


                                     250
                                           0    20       40       60       80      100   120   140

                                                                Temperature [oC]

University of
Wales                            MOS-AK meeting, Leuven, September 2004
Extraction of the RC Thermal Network Parameters:
Deconvolution Method
                           Az   Y z   exp z  exp z 
                        d
                        dz
     Deconvolving above equation by the fixed function exp(z-exp(z)), Y(x)
     spectrum can be extracted from the transient response.




University of
Wales                       MOS-AK meeting, Leuven, September 2004
    Thermal Transient Response
    Function: SML5020BN MOSFET




University of
Wales           MOS-AK meeting, Leuven, September 2004
   Thermal Transient Response Function:
   STY15NA100 MOSFET
                                            160

                                                              Experiment          STY15NA100 MOSFET
                                            140               RC Network
                Junction Temperature [ C]



                                            120         RFoster: 4.8794 41.215 4.9488 10.9174
                o




                                                        CFoster: 1.369 1.869 49.706 22.562
                                            100
                                                        RCauer: 15.175 39.986 6.7996 2.79e-6
                                            80          CCauer: 0.752 1.2298 33.208 8.8187e7

                                            60


                                            40
                                                                                                       PDISS = 2W
                                            20                                                         T0 = 20.7OC

                                             0
                                                  0.1               1              10             100                1000

                                                                                 time [s]



University of
Wales                                                         MOS-AK meeting, Leuven, September 2004
Cross sectional view of HEXFET
                                                         The introduction of the polysilicon-gate
                                                         allowed the structure to be self aligned,
                                                         and allows a cellular structure which
                                                         increases the packing density.


                                                         This increases the active channel to
                                                         total area ratio significantly compared to
                                                         rectangular cell or striped structures
                                                         Fairly economical process – 6/7 masks
                                                         cf. 20-28 for CMOS
                                                         Note whole of upper surface is coated
                                                         with Source metal. This makes
                                                         processing and packaging easier.
                                                         Typical cell densities are greater than
                                                         2M/in2 (300K/cm2)




University of
Wales           Source
                    MOS-AK meeting, Leuven, September 2004
                contact
                    SEM of trench structure




Presented ISPSD 2001
J.Zeng et.al. – Fairchild
Ultra dense trench 1.1mm trench spacing – 0.18mW.cm2
    University of
    Wales                   MOS-AK meeting, Leuven, September 2004
 Where does RDS(ON) come from?
 Source                                                   RDS(ON) is made up of the
     Rcontact              Gate                            series combination of all the
                                                           parts of the device between
        Rsource Rchan Ra                                   the source and drain where
                              Rjfet                        there is a voltage drop

                                                          Some of these components
                                                           are negligible in some
                              Rdrift
                                                           voltage ranges

                                                          An approximate value can
                                                           be arrived at using hand
                                                           calculations.
 N- epitaxial layer

                              Rsub                        RDS(ON) = Rsource + Rchan + Ra
                                                           + Rjfet + Rdrift + Rsub
                                  Rcontact
University of
                                             Note: all calculation carried out
Wales                       Drain meeting, Leuven, September 2004
                             MOS-AK          per unit area
Electrical Compact Models:
Power MOSFET




University of
Wales           MOS-AK meeting, Leuven, September 2004
                                         Power MOSFET SML5020BN (Semelab plc.)

                                        20
                                                                                            VGS = 5.3V
                                                 measurements
                                        15                            simulation
                drain current, ID [A]




                                        10                                                  VGS = 4.8V



                                         5
                                                                                            VGS = 4.3V


                                         0
                                             0      2             4             6            8           10
                                                                voltage, VDS [V]



University of
Wales                                              MOS-AK meeting, Leuven, September 2004
                                     Power MOSFET SML5020BN (Semelab plc.)


                                    25   ____ simulations                                                             500
                                         ____ measurements
                                    20                                                         8                      400
                Drain Current [A]




                                                                                                                            Drain Voltage [V]
                                                                                                   Gate Voltage [V]
                                    15                                                         6                      300

                                    10                                                         4                      200

                                     5                                                         2                      100

                                     0                                                         0                      0

                                    -5
                                            0          20       40        60        80   100
                                                                 time, t [ms]




University of
Wales                                           MOS-AK meeting, Leuven, September 2004
      Electrical Compact Models:
      PiN Diode Compact Model




University of
Wales             MOS-AK meeting, Leuven, September 2004
                                                                                                    6e+17

                                                                                                                                                                      Plasma Shape Prediction: FEM




                                             Excess Carrier Concentration (cm-3)
                                                                                                    5e+17




                                                                                                                                       0m
                                                                                                                                         s
                                                                                                                                    0.5
                                                                                                                                       02
                                                                                                                                          ms
                                                                                                    4e+17
                                                                                                                                               0.6
                                                                                                                                                  32m
                                                                                                                                                        s


                                                                                                    3e+17

                                                                                                                                                                 0.852ms




PiN Diode Compact                                                                                   2e+17
                                                                                                                                                                           1.122ms

                                                                                                                                                                                       1.305ms

                                                                                                    1e+17
Model:                                                                                                                                                                                             1.519ms




                                                                                                                   0
                                                                                                                                0                           20                40                   60              80     100
Plasma Decay During Turn-off
                                                                                                                           6




                                                                              Excess Carrier Concentration (x 10 17cm-3)
                                                                                                                                                        Plasma Shape Prediction: Compact Model
                                                                                                                           5




                                                                                                                                    0m
                                                                                                                                      s
                                                                                                                           4        0.5
                                                                                                                                       02
                                                                                                                                          ms

                                                                                                                                           0.6
                                                                                                                                              32m
                                                                                                                           3                     s




                                                                                                                                                                 0.852ms
                                                                                                                           2
                                                                                                                                                                             1.122ms
                                                                                                                                                                                        1.305ms
                                                                                                                           1
                                                                                                                                                                                                       1.519ms



                                                                                                                           0
                                                                                                                           0.000                    0.002                  0.004                 0.006           0.008   0.010
                                                                                                                                                                             Base Width (cm)
                                            A                                                                                                                                                                                     K
                                                                                                                           p+                                                n- Base                                         n+




   University of
   Wales                   MOS-AK meeting, Leuven, September 2004
                                              14                                                                     20
                                                                Diode BYT 12PI-1000 (ST Microelectronics)
                                              12
                                              10                                                                     0
                                               8

PiN Diode Compact                              6                                                                     -20




                                                                                                                            voltage, VA [V]
                            current, IA [A]
                                               4
Model:                                         2                                                                     -40
                                               0
Diode Turn-off                                 -2                                          IA, Experiment            -60
                                               -4                                          IA, Compact model
                                               -6                                          VA, Compact model         -80
                                               -8                                          VA, Experiment

                                              -10                                                                    -100
                                                    0.0   0.1        0.2       0.3        0.4      0.5         0.6
                                                                           time, t [ms]



                                                Extracted values of the diode parameters: A=0.1cm-2,
                                                W=0.00632cm,  =1.418x10-7s, Nd=1x1014cm-3,Vbi= 1V,
                                                Irp0=1x10-11A, Iln0=1x10-12A, Np= 1x1020 cm-3,  = 5x10-5cm




   University of
   Wales           MOS-AK meeting, Leuven, September 2004
Electrical Compact Models:
Non Punch Through IGBT Compact Model




University of
Wales           MOS-AK meeting, Leuven, September 2004
Electrical Compact Models:
Punch Through IGBT Compact Model




University of
Wales           MOS-AK meeting, Leuven, September 2004
Electrical Compact Models:
NPTIGBT and PTIGBT Compact Model Parameters
                A       Total IGBT active area (cm2)
                ADG     Gate-drain overlap area (cm2)
                BVn     Breakdown voltage index
                BVf     Breakdown voltage multiplication constant
                CGS     Total gate-source oxide capacitance (nF)
                COXD    Total gate-drain overlap oxide capacitance (nF)
                ILN0    Electron end leakage saturation current (A)
                KPLIN   Transconductance in linear region (A/V2)
                KPSAT   Transconductance in saturation region (A/V2)
                ND      Base region doping density (cm-3)
                Np      Gaussian peak doping density (cm-3)
                VBI     Junction built in potential (V)
                VTD     Gate-drain overlap area threshold voltage (V)
                VTH     Threshold voltage (V)
                W       Base region width (cm)
                l       Channel length modulation parameter (V-1)
                q       Transverse field factor (V-1)
                       Doping spreading factor (cm)
                       Ambipolar lifetime (s)

                P      Hole lifetime inside the buffer layer (s)
                WB      Buffer layer width (cm)
                nF      Emitter efficiency
                NB      Buffer layer doping density (cm-3)
University of
Wales                          MOS-AK meeting, Leuven, September 2004
        IGBT Compact Model: Clamped Inductive
        Load Circuit – Gate Controlled Turn-off

                                                                 Value for the Vaa is chosen
                                                                 to be greater (500V) than the
                                                                 maximum clamping voltage
                                                                 Vclamp (300V).




   Clamp inductive load circuit




University of
Wales                   MOS-AK meeting, Leuven, September 2004
                                       8

                                       7                                                                         Clamped Inductive Load Circuit – Gate
                                       6
                                                                                  Vclamp = 100V
                                                                                  Vclamp = 200V                  Controlled Turn-off: At the beginning of the
                                                                                  Vclamp = 300V
                                                                                                                 turn-off process, as soon as gate voltage
                   anodeCurrent [A]




                                       5

                                       4                                                                         decreases below VTH the MOS channel is
                                       3                                                                         turned-off. Then, the channel current (Ich), which
                                       2                                                                         is an electron current, decreases abruptly and
                                       1
                                                                                                                 the anode voltage starts to rise. When the anode
                                       0
                                                                                                                 voltage reaches the clamp voltage (VA = Vclamp),
                                           16   17   18     19      20       21      22           23        24
                                                                                                                 it stays constant. The remaining current tail will
                                                                 time [ms]                                       decay with a longer time constant via carrier
                               350
                                                                                                                 recombination and diffusion. As suggested by
                                                                                                                 the arrow, the higher the clamping voltage
                               300
                                                                                            Vclamp = 100V
                                                                                                                 (Vclamp) the higher will be the initial current tail
                               250                                                          Vclamp = 200V        size.
anodeVoltage [V]




                                                                                            Vclamp = 300V

                               200


                               150


                               100
                                                                                                                      Simulated NPTIGBT anode current and
                                      50
                                                                                                                      voltage turn-off waveforms
                                       0
                                           16   17   18     19      20       21       22          23        24

                                                                 time [ms]

                                            University of
                                            Wales                                      MOS-AK meeting, Leuven, September 2004
     Clamped Inductive Load Circuit – Gate Controlled Turn-off:


                      1.6e+17
                                                                                    NPTIGBT
                      1.4e+17
                                                                                    Vclamp = 200V
                      1.2e+17

                      1.0e+17
           pl [cm ]
          -3




                      8.0e+16

                      6.0e+16

                      4.0e+16

                      2.0e+16

                        0.0


                                14   15       16      17       18      19      20        21         22

                                                           time [ms]


Carrier concentration at the left (anode) plasma edge decay during
NPTIGBT turn-off - carrier concentration decreases monotonically during turn-off

University of
Wales                                     MOS-AK meeting, Leuven, September 2004
                   Clamped Inductive Load Circuit – Gate Controlled Turn-off:

                   8                                                                                     350


                   7                                                                                     300
                                                                                                                                               Vclamp = 100V
                   6                                             Vclamp = 100V
                                                                                                         250                                   Vclamp = 200V
                                                                 Vclamp = 200V




                                                                                      anodeVoltage [V]
                                                                                                                                               Vclamp = 300V
anodeCurrent [A]




                   5                                             Vclamp = 300V
                                                                                                         200
                   4

                                                                                                         150
                   3

                   2                                                                                     100

                   1
                                                                                                         50

                   0
                                                                                                           0
                       16       17     18               19       20              21                            16   17   18               19   20              21

                                            time [ms]                                                                         time [ms]




                        Simulated PTIGBT anode current and voltage turn-off waveforms –
                        PTIGBT has a shorter turn-off time than a corresponding NPTIGBT since the
                        carriers are cleared away from the PTIGBT base by the depletion region as it
                        reaches the buffer layer.

                       University of
                       Wales                                 MOS-AK meeting, Leuven, September 2004
                IRG4BC20UD (International Rectifier) IGBT


         500                                                                15                     500                                                               15
                                                          Turn-On                                                                                  Turn-Off
         400                                                                12                     400                                                               12



         300                                                                9                      300                                                               9

                                               -------Experiment
VA [V]




                                                                                          VA [V]
                                                                                 IA [A]
                                                                                                                                        -------Experiment




                                                                                                                                                                          IA [A]
         200                                   -------Compact Model         6                      200                                                               6
                                                                                                                                        -------Compact Model

         100                                                                3                      100                                                               3


           0                                                                0                        0                                                               0


         -100                                                               -3                     -100                                                              -3
                    0.0   0.1   0.2      0.3     0.4       0.5        0.6                                    0.0   0.1   0.2      0.3    0.4       0.5         0.6
                                  time [ms]                                                                                time [ms]



                  Anode current and voltage turn-on                                                      Anode current and voltage turn-off
                  waveforms                                                                               waveforms




                University of
                Wales                                  MOS-AK meeting, Leuven, September 2004
                ET PiN Diode Simulation




University of
Wales                   MOS-AK meeting, Leuven, September 2004
               ET PiN Diode Simulation


                                                   Anode Voltage vs. time




Anode Current vs. time


   University of
   Wales                MOS-AK meeting, Leuven, September 2004
  Step-Up Converter:
  Schematic of an Electro-Thermal Model




                f=20kHz




University of
Wales                     MOS-AK meeting, Leuven, September 2004
  Step-Up Converter:
  Drain Voltage Vs. Time




University of
Wales             MOS-AK meeting, Leuven, September 2004
  Step-Up Converter:
  Output Voltage and Junction Temperature




University of
Wales             MOS-AK meeting, Leuven, September 2004
  Synchronous Buck Converter:
  Topology and Typical Power Losses

                     L
                                 +
          Q1                R
    +                                                             miscellaneous 1%
                                       inductor 10%
   Vin          Q2   C
                                  Vo
                                                                           Control FET
                                                                           Q1 36%


                                       input
                                       capacitor
                                       30%
                                                                     Synchronous FET
                                                                     Q2 23%



University of
Wales                    MOS-AK meeting, Leuven, September 2004
  Isolated Forward Converter:
  Topology and Typical Power Losses
                                      L
                N:1
                                                R +
                      Qs1
                                        C         Vo
   +
                      Qs2                                      miscellaneous 8%
   Vin                             inductor 10%
         Qp                                                            Primary
                                   bias 9%                             MOS FET
                                                                       16%




                                transformer                            Secondary
                                22%                                        FET
                                                                       MOS s
                                                                       35%



University of
Wales                 MOS-AK meeting, Leuven, September 2004
                Conclusions
MOSFET model is simple cf. deep sub
 micron
Electro Thermal interactions are key
Bipolar Plasma modelling is very
 challenging
Long real times for simulations


University of
Wales           MOS-AK meeting, Leuven, September 2004
                Aknowledgement
Thanks to Dr.P.Igic




University of
Wales             MOS-AK meeting, Leuven, September 2004

				
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