crosslight software, inc., burnaby,...

Crosslight Software, Inc., Burnaby, Canada

• Technology Computer Aided Design for semiconductor devices

What is TCAD?

• TCAD is critical for semiconductor device industry, both discrete and

integrated

• It saves time and money, provides deep understanding of the physics

Why TCAD?

• More realistic

• Device nature requires 3D (i.e. Superjunction Power Device, CIS)

Why 3D TCAD?

A Canadian company with a history

of more than 15 years

A pioneer and global leader of

optics and photonics TCAD

A fast growing TCAD provider for

silicon devices

APSYS

(Device Simulator)

CSuprem

(Process Simulator)

PICS3D

(Photonic IC

Simulator)

LASTIP

(Laser Diode)

2D/3D

TCAD

•Traditionally 3D bulk TCAD is time consuming, may take even longer than real

fabrication time

•Not Acceptable for today’s semiconductor industry

Time is the Money! Efficiency is the Key!

•Instead of bulk simulation, Crosslight adopted a new way to stack the 2D planes

in the z direction to ensure efficiency and accuracy

Crosslight’s New Approach

•Quasi-3D neglects the inter-plane dopant diffusion to save time at first, when

everything is ok, full 3D will take account all the plane to plane interaction

Quasi-3D vs. Full 3D

Power

NPN BJT

Metal

Debiasing

LDMOS

SJ LDMOS

CIS

3D-FDTD

FINFET

Specialty

MEMS

We use a vertical power NPN BJT as anexample. From layout, generate the GDSII file

Emitter

STI (Shallow Trench Isolation)

Base

Collector

Spacer/Nitride

BEOL is neglected for simplicity

Mask Layers (.msk file)

GDS2MASK.exe

Z structure (.zst file)

Z Direc. Cut(.cut file)

Crosslight provides anintegrated 3D structurecreation tool to simplifythe 3D modeling process.

1•Load the GDSII file

2•Cut the layout in the z

direction

3•The .msk and .zst files are

automatically generated

2D planes (x,y)

z direction

The z structure file (.zst file) isused to control the cut locationand planes in the z direction

The mask file (.msk file) is usedto generate mask layers in theinput file for CSuprem

CSuprem is Crosslight’sversion of SUPREM IV,originally developed by theStanford University.

You can choose from quasi3 dimensional or full 3Dsimulation, quasi3d meansthe diffusion between thez planes is not consideredto boost up speed

Emitter

Base

Collector

Nitride Spacer

STI

Advanced Physical Models ofSemiconductor Devices, is basedon 2D/3D finite element analysisof electrical, optical and thermalproperties of the semiconductordevices, with silicon as a specialcase.

1.00E-19

1.00E-17

1.00E-15

1.00E-13

1.00E-11

1.00E-09

1.00E-07

1.00E-05

1.00E-03

1.00E-01

0.00E+00 2.00E-01 4.00E-01 6.00E-01 8.00E-01 1.00E+00 1.20E+00

Ic &

Ib

(A

/m

)

Vbe (V)

Gummel Plot

2D center cut: Total(electron and hole)Current Contour Plot

Power

NPN BJT

Metal

Debiasing

LDMOS

SJ LDMOS

BCD

CIS

3D-FDTD

FINFET

Specialty

MEMS

LDMOS from ST

Huge Size! Metal Resistant is no longer

negligible

•Metal resistant comparable to device Rdson

•Different metal pattern will yield different Res.

Lump model is not good

•3D nature, too complicated to model using

lump elements.

The metal interconnect for large sized power MOSFET generally contribute toconsiderable amount of total resistance, a 3D model is generally necessary to determinethe resistance from the metal lines.

Layout:

Metal2

Metal1

Gate Poly

Via1

Contact

After Contacts CMP After Via1 CMP

After Metal2 CMP

0.00E+00

5.00E-03

1.00E-02

1.50E-02

2.00E-02

2.50E-02

3.00E-02

3.50E-02

4.00E-02

0.00E+00 5.00E-02 1.00E-01 1.50E-01

2D cut from center

I-V Curve

Contact

Metal1

Via1

Metal2

Power

NPN BJT

Metal

Debiasing

LDMOS

SJ LDMOS

CIS

3D-FDTD

FINFET

Specialty

MEMS

2D cut:Net Doping

Drain

Gate

Source

2D cut: Electric Field

Highest Electric Field islocated under gate edgein the STI, other areasare pretty flat

Contour Plot of E. Field

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0.0000000

0.0000005

0.0000010

0.0000015

0.0000020

0.0000025

0.0000030

0.0000035 Id

Gm

Vg (V)

Id

0.0000000

0.0000005

0.0000010

0.0000015

0.0000020

0.0000025

0.0000030

Gm

Vth=0.8V

Threshold and Transconductance

0 20 40 60 80 100

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

Id (

Lo

g S

ca

le)

Vd (V)

Id

Reverse Breakdown

BVds0=95V

Quasi-saturation

Hot carrier pick upI-V curve

Vg=12V Vd=55V Self Heating with thermal conductance of 0.1 W/mK

2D cut to Show Net Doping

SuperJunction LDMOS Normal LDMOS

Superjunction has lower Surface field than normal LDMOS with the same drain bias.

6E+5 V/cm 8E+5 V/cm

0 10 20 30 40 50 60 70 80 90

1E-14

1E-13

1E-12

1E-11

1E-10

1E-9

1E-8

1E-7

1E-6

1E-5

Dra

in C

urr

en

t (A

)

Drain to Source Voltage (V)

Normal LDMOS

SuperJunction LDMOS

Comparison of Breakdown Voltage of SuperJunction LDMOS and normalLDMOS, a clear breakdown voltage increase for Superjunction LDMOSwith the same process condition.

Power

NPN BJT

Metal

Debiasing

LDMOS

SJ LDMOS

CIS

3D-FDTD

FINFET

Specialty

MEMS

2D-Cut of the Optical Generation

Optical Simulation 3D-FDTD

Relative Energy Density

2D-Cut of the Incident Light relative energy density

Finite-difference time-domain (FDTD) is acomputational electrodynamics modelingtechnique, dealing with electromagneticwave interactions with material structures.

Power

NPN BJT

Metal

Debiasing

LDMOS

SJ LDMOS

CIS

3D-FDTD

FINFET

Specialty

MEMS

Gate

Source

Drain

Top-Down Current Magnitude

I-V curve

Dual Channel

3D LOCOS growth UMOS with rotated planes

Hybrid IGBT

LDMOS

IGBT

UMOS Id-Vg

Electro Meter

RF Switch

V-MEMS Tunable VCSOAs

PC: HP Laptop with Intel Core2 P8600@2.4G Memory 6G, Video card: 512M Nvidia 9600M GT

System: Windows Vista 64bit

MEMS-

Electrometer

MEMS-RF

Switch

NPN BJTQuasi3D

NPN BJT Full3D

Metal Interconnect

SJLDMOS

Quasi3D

SJ LDMOSFull3D

Time 40s 60s 22m 40m 17m 50m 92m

Mesh 1198 1068 36455 36455 115700 79049 85931

Planes 15 5 25 25 154 33 33