ECPE Workshop

“Failure Mechanisms and Reliability of Wide Band-Gap Devices”

16 – 17 October 2014, Rouen, France

Jean ROUX / Hamamatsu Photonics France / October 17th 2014

OUTLINES

- Hamamatsu Short Introduction

- Power Devices Context and Failure Mecanisms

- Emission Microscopy Solutions ( UV and NIR approachs )

- Obirch Solutions ( Si and SIC approach )

- Thermal Emission Solutions ( Lock-in Thermography )

- Peripherals solutions

- Conclusions

Confidential 3

Factories of HPK

Ichino factory

Toyooka factory

Factories are located in provincial city: Hamamatsu

Misue factory Shingai factory

Tenno glass works

Miyakoda factory Joko factory

Solid state division

Electron tube division

Laser group System division

Central research lab. Kurematsu research lab.

R&D center

(in front of Hamamatsu station)

Headquarter

Joko factory

Headquarter

Ichino factory

Tenno glass works

Toyooka factory

Shingai factory

Mitsue factory

Miyakoda factory

Central research lab.

Kanematsu research lab.

Lake Hamana

Pacific Ocean

River Tenryu

Headquarter 1 Factory 7 R&D center 2 + 1 @Tsukuba-city Sales office 7 areas in Japan

Hamamatsu city

Shizuoka prefecture

Confidential 4

High-tech factory in fields

Joko Factory <System Division>

Cameras

Life science systems

Medical systems

Semiconductor failure analysis systems

Material evaluation systems

Spectral photometry/ ultra-fast photometry system

Joko factory

Tenryu river

Tomei express way

About 400 employees in 5 buildings [21,232 m²]

Confidential 5

Fault Localization Tools provided by HPK HPK provides photon related semiconductor

Fault localization tools by using HPK hypersensitive detectors and optical technologies

Single die level

millimeter order

Transistor level

micron-submicron order

THEMOS Thermal emission

microscope

iPHEMOS Inverted type photo

emission microscope

uAMOS IR-OBIRHC

analysis system

TriPHEMOS Time resolved imaging photo

emission microscope

Thermal emission OBIRCH Photo emission DALS TRIEM EOP/EOFM

Fault localization tools Narrow down from O(mm) to O(um/sub-um)

Thermal emission detection

Laser Stimulation Photo emission detection

Confidential 6

Applicable Range of Failure Analysis Tools

Static

Dynamic

Fault

Error

Short High resistance Open

Current Timing (Current)

Type of analysis And tools

Thermal emission

OBIRCH

PEM

DALS = SDL/LADA

TRIEM

EOP/EOFM

Type of target

Light stimulation Detecting light Detecting heat OBIRCH = Optical Beam Induced Resistance Change, PEM = Photo Emission Microscopy, DALS = Dynamic Analysis by Laser Stimulation,

SDL = Soft Defect Localization, LADA = Laser Assisted Device Alteration, TRIEM = Time Resolved Imaging Emission Microscopy, EOP = Electro Optical Probing, EOFM = Electro Optical Frequency Mapping

Understanding cover range of each techniques and select suitable tools

Powers Devices Context and Failure Mecanisms

◆What is trend of power devices?

Electronic

breakdown field (MV/㎝)

Thermal

conductivity (W/㎝･℃)

Melting point (℃)

Saturated

electron drift

velocity (×107㎝/s)

Band gap (eV)

Si

GaN

SiC

Performance at High Temperature : 3x

Performance at High Voltage : 10x

Decrease of Power Loss : 100x

Tolerance against Radiation : 3x

Performance at High frequency : 10x 50x

4

5.2

3000

3.2

4

Reliability mechanisms in GaN based power devices Source : J.Wurfl – FBH Berlin – ESREF 2014 Berlin – Tutorial.

« Etude des mécanismes de défaillances et de transport dans les

structures HEMTs AlGaN/GaN » (Source : Thesis M.BOUYA –Université Bordeaux1 - July 2010)

EMMI VIS - IR ( 0,4µm - 1,1µm ) / Standart Electro-Luminescence

Defect at interface Buffer Gan / Substrat Sic

Passivation Defects (delamination) at interface Passivation/Semiconductor

Defect at interface Metal/ Semiconductor ( Schottky diode )

Thermal Emission requiring Temperature Measurment ( 3,7µm - 5,2µm )/ HOT SPOTS

Defect ohmic contacts at high temperature Ti/Al/Ni/Au

EMMI UV ( 0,2µm - 0,4µm )/ UV Electro-Luminescence HOT ELECTRONS

Defect in the Drain-Source area under high Electron field

Obirch Analysis

Interconnexions defects

MIM capacitance defects

Metal to Metal shorts

Confidential 12

PHEMOS

PHEMOS-1000 iPHEMOS series

Equipment for PEM (=Photo Emission Microscopy)

Standard model and inverted model for backside analysis available

13/50 Confidenti

al

0

Q.E

. of

cam

era

in P

HEM

OS

syst

em

(%

)

20

40

60

80

100 V

olt

age

of

po

we

r su

pp

ly (

V)

1.0

1.5

0.5

0

2.5

3.0

2.0

104

102

108

106

Rad

iation

en

ergy (W

/m3)

Black body radiation

T = 300K (r.t.)

Wavelength (um)

0 2.5 3.0 1.0 1.5 0.5 2.0

Transparent to silicon substrate

C-CCD

InGaAs

Emmi-X

Si-CCD

InSb

5µm

Spectral sensitivity

0

10

20

30

40

50

60

70

80

90

100

400 600 800 1000 1200 1400 1600

Wavelength [nm]

Qua

ntum

Effi

cien

cy [%

]

C4880-59

C8250-26

◆Detector: Spectral sensitivity

PHEMOS spectral sensitivity

For Si

For SiC, GaN

Si-CCD cameras for GaN / SiC

Exemple of defects at Metal / Semiconductor interface ( Shottky contact ) in

standart electro-luminescence (Source : Thesis M.BOUYA –Université Bordeaux1 - July 2010)

Exemple of defects in thre Drain-Source area under high Electron field (1/2) (Source : Thesis M.BOUYA –Université Bordeaux1 - July 2010)

At low Vds , EMMI UV signature is similar to EMMI IR , Increasing Vds, shows new EMMI signature (UV

Exemple of defects in thre Drain-Source area under high Electron field (2/2) (Source : Thesis M.BOUYA –Université Bordeaux1 - July 2010)

At high Vds (170V to 200V ), the EMMI IR becomes strong and leads to camera saturation , whereas observing

EMMI in UV conditions ( EMMI UV) contributes to accurate the defect localization along the active area

Confidential 22

PHEMOS for SiC

Specifications ・Camera for Emission :Si-CCD ・Laser for OBIRCH :532nm ・Interlock for Laser & High Voltage

Confidential 23

Obirch

Equipment for OBIRCH analysis (Optical Beam Induced Resistance Change)

uAMOS-1000 OBIRCH option for PHEMOS series also available

Confidential 24

Mechanism of OBIRCH Analysis

DUT

Laser (wavelength 1.3μm ( Si transparency ) generate no electron-hole pair at p-n junction)

Scanning

Image of ∆I or ∆V

Current

OBIRCH amplifier

∆V or

∆I

OBIRCH image

Red : +∆ (Increase) Green : -∆ (Decrease)

Applying electrical bias Monitoring current or voltage

Imaging change of the current or the voltage OBIRCH image

Current path

Abnormal resistance spot

No change for circuit unrelated to an analysis line.

Heat Spot

Laser spot on current path I/V change Generate OBIRCH image

Confidential 25

Resistance Change by Laser Irradiation

Without laser irradiation

Laser heat makes R increase (TCR* is plus) and then

current decrease

ΔI ≈ – (ΔR/V) * I2

V = (R+ΔR )* (I – ΔI)

on metal

A V

I-ΔI R+ΔR

Laser

Heat

ΔI ≈ + (ΔR/V) * I2

Laser heat makes R decrease (TCR* is minus) and then

current increase

on semiconductor

V = (R –ΔR )* (I + ΔI)

A V

I+ΔI R-ΔR

Laser

Heat

With laser irradiation

A V

I R

V = R * I

No change *TCR = Temperature Coefficient of Resistance

Current change depend on TCR (metal plus, semiconductor minus)

Confidential 26

History of OBIRCH Amplifier

1997 2010 2012 2013

Sensitivity of high sensitive amplifier

Voltage range of high sensitive amplifier

10pA 3pA

+10mV - +25V -25V - +25V

Installed functions Current detection head for high voltage /high current laser 45degree scan

1st 2nd 3rd 4th 5th 6th Generation of amplifier

Minor upgrade Lock-in Noise cancelling Four quadrants Sensitivity improvement (noise reduction)

Covering four quadrants of voltage and current

-100 uA +100 uA

-25V

+10V

-10V

-100 mA

Source

Source Sink

Sink +25V High

Sensitive mode

Standard mode

Conventional type cover range

+100 mA

System noise reduction by lock-in function

Improvement of active noise cancellation function

Amplifier circuit noise reduction by circuit design

History of OBIECH amp. = S/N improvement + New functions installing

Confidential 27

OBIRCH Amplifier Covering 4 Quadrants

V1 V2

Mo

du

le1

Mo

du

le2

i1 i2

V1 V2

Mo

du

le1

Mo

du

le2

Rshort

i1 i2 ileak

V1 > V2

If i2 < ileak

V1 V2

Mo

du

le1

Mo

du

le2

Rshort

i1 i2 ileak

OBIRCH amplifier

Short between different voltage modules

In normal case, no interference between different voltage modules

Latest 6th generation OBIRCH amplifier ( Cover whole quadrants)

Use this area

-25V

+10V

-10V

+25V

5th generation OBIRCH amplifier ( Cover first quadrant)

-100 uA +100 uA

-25V

+100 mA

+10V

-10V

-100 mA

+25V

-100 uA +100 uA +100 mA -100 mA

High sensitive mode

Standard mode

OBIRCH analysis

In abnormal case, interference between different voltage modules in sometimes

New amplifier Expanding cover range of OBIRCH analysis

28/46

Confidential

New Obirch generation and performances comparison

Operation

mode

Voltage range Max current Detectability Active noise

cancellation

STD High

Sensitive

STD High

Sensitive

STD High

Sensitive

STD High

Sensitive

A8755

-01

Vol1&2,

Cu1

10mV to

10V

10mV to

25V

100mA 100uA 10n

A

10pA NO NO

A8755

-02

Vol1&2,

Cu1

10mV to

10V

10mV to

25V

100mA 100uA 10n

A

10pA NO NO

A8755

-03

Vol1&2,

Cu1

10mV to

10V

10mV to

25V

100mA 100uA 1nA 3pA NO NO

A8755

-04

Vol1&2,

Cu1

10mV to

10V

10mV to

25V

100mA 100uA 1nA 3pA HAVE NO

A8755

-06

Vol1&2,

Cu1

-10V to

10V

-25V to

25V

-100mA

to 100mA

-100uA

to 100uA

1nA 3pA HAVE NO

◆Why compound (SiC , GaN ) power devices match UV?

Property Si GaAs SiC(4H) GaN Diamond

Band gap (eV) 1.12 1.43 3.26 3.39 5.47

Emission wavelength (nm) 1107 867.1 380.4 365.8 226.7

Wave length [nm]

Tra

nsm

issiv

ity [%

]

SiC substrate characteristic

OBIRCH

375 nm

(3.31 eV)

As

B

3.26 eV

Valence band

Conduction band

hole

electron

(380nm)

OBIC

OBIC

405nm

(3.06 eV)

As

B

3.26 eV

Valence band

Conduction band

hole

(380nm)

No OBIC

Shorter wavelength laser(375nm) Longer wavelength laser(405nm)

OBIRCH （Laser stimulation to SiC）

OBIRCH Excitation laser wavelength

Sic, GaN

Short Wavelength Long

High Excitation efficiency Low

High Resolution Low

Si

Wide Bandgap Narrow

NUV NIR

λ = h / Eg

E = h / λ

R = λ / 2NA

NUV optics can be the good analysis method

Confidential 32

NUV (=Near UV)-OBIRCH Analysis for SiC

Band gap (eV)

Critical field (MV/cm)

Electron mobility (cm2/Vs)

Saturated electron drift velocity (cm/s)

Thermal conductivity (W/cmK)

Si SiC (4H)

1.12 3.26

0.3 2.8

1350 1000

1.1x107 2.2x107

1.5 4.9

SiC/Si

2.9

9.3

0.74

2.0

3.3

Characteristics of Si and SiC

Data courtesy to ITES Co., Ltd.

SiC: Higher thermal conductivity More difficult to heat 532nm laser: Smaller spot size Higher power density (6X) X Higher transparency (3X?)

532nm laser can heat SiC sample more effective than 1300nm laser.

SiC MOSFET [Gree] VDSS:1200V, VGS:25V

Sample

NUV-OBIRCH: applicable

to SiC device

1300nm laser

532nm laser

Resolution improvement check Sample #2 (EOS all plugs leak)

Low magnification

Signal detection improvement check Sample #1 (EOS drain source leak)

High magnification High magnification Low magnification

No signal (diffused?) No signal

No signal

Indistinct signal

Estimation result

Band gap and laser wavelength

Ener

gy

(eV

)

Wavelength (nm)

SiC

Si

λ =

53

2n

m

λ =

13

00

nm

Spot size 2/5 Power density 6X Transparency 3X?

200 400 600 800 1000 1200 1400 0

1

2

3

4

5

6

400 600 800 1000 1200 1400 0

10

20

30

Tra

nsp

are

ncy

(%

)

Wavelength (nm)

n-type SiC t = 350um

◆High current probe head

OBIRCH for high voltage/currency

For high voltage : ～5kV (90VA)

For high currency : 6.3A / 250V

OBIRCH amp (standard)

High sensitivity mode: 25V / 100uA

Constant voltage: 10V / 100mA

Confidential 34

Current Detection Head

Lock-in unit

DC OUT 24V

BNC cable

DUT

Ext. Power Supply

or

Tester

+V

COM

*For example to analyze at Vcc line A9187 is available to analyze any line by

inserting this probe head to the line.

IN

OUT

OBIRCH Amp.

Voltage amplified OBIRCH Image

I/V convert

I

Signal detected by magnetic field change

caused by current change (I) LASER Detection is indirectly with

power supply line.

Large current 6.3A

High Voltage 250V

Both-directions current

Option 3kV / 15VA available

*Current and voltage

specification is depend on

power supply, connector,

wire line, etc.

Problem : Influence of power supply noise

High Current Probe Head : Digital Lockin Amplifier Needed

Confidential 35

Delay Point Detection by Digital Lock-in 0 degree 180 degree 360 degree

Laser modulation

OBIRCH signal (normal operation)

OBIRCH signal (delay operation)

t

t

t

Conventional lock-in image = Amplitude image

Digital lock-in sampling image (can create motion image) = Phase image

OBIRCH signal delay ↑

Slow heating & cooling by laser irradiation and stop

Normal portion is reaching to high temperature. Abnormal portion start to heat up at this timing.

Both portion heated to almost same temperature.

After laser irradiation stop, normal portion cool down, heat can't escape and remain at abnormal portion.

Peculiar point of heating & cooling can be extracted by this technique.

Confidential 36

THEMOS

Equipment for thermal emission microscopy

THEMOS-1000 & THEMOS mini

Standard model and compact model available

37/50 Confidenti

al

2014

History of the thermal emission detector

Confidential 38

Specification of Thermal Cameras Generation 1st 2nd 3rd 4th 5th 6th

Model IR-M300S IR-M500 IR-M600 IR-M700 InSb InSb HR

Detector type PtSi InSb

Spectral range 3 - 5μm 3.7-5.2μm

Array format 256 X 256 512 X 512 801 X 512 320 X 240 640 X 512

Cooling type Stirling cycle

NETD (degree) 0.2 0.15 0.08 0.08 0.025 0.02

NETD = Noise Equivalent Temperature Difference Resolution of heat

Latest InSb camera - High sensitivity - 640x512 resolution - Plug and start - Without LN2 supply

HPK designed lens -High NA, -Fit in turret, -Optimized NA and W.D.

iPHEMOS with InSb THEMOSmini THEMOS-1000

InSb camera

High sensitive InSb camera and specified objective lens are available.

39/50 Confidenti

al

Optimized the driving parameters

of InSb sensor

Optimized the optics

How to get high sensitivity

40/50 Confidenti

al

New InSb

Conventional

Consumption (μW)

Dete

cta

bility

Comparison of the detectability

２X

DUT： discrete parts on the PCB

Confidential 41

Improvement of Thermal NanoLens

XYZ move

Conventional NanoLens (separate type)

New NanoLens (built-in type)

Feature of new NanoLens Built-in to 8X objective lens Vibrated self align contact Direct contact without oil Improved sensitivity and resolution (NA: more than 1.5 2.6max.)

Objective lens 8X (NA0.75) New thermal NanoLens 28X Objective lens 8X + digital zoom

InSb camera images

New thermal NanoLens Easy operation + Higher performance

Resolution = 𝝀

𝟐𝑵𝑨 =2.7um (𝝀 = 4um) Resolution =

𝝀

𝟐𝑵𝑨 = 0.77um (𝝀 = 4um)

◆High voltage Thermal lock-in with a power amp

THEMOS Thermal lock-in

Thermal lock-in unit

-45V ～ +45V

Power distribution amp

HEOPS-3B10

Input -10V ～ +10V

Output -3kV ～ +3kV

Voltage: -3kV - + 3kV(10mA)

For power devices, high voltage bias is needed. Thermal lock-in

has the capability to operate higher voltage operation.

Standard lock-in can operate -45V - +45V(100mA).

Confidential 43

Thermal Lock-in Function On

Off

On

Off

On

Off Power supply

Heat

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16

Without lock-in (S/N=4.4) With lock-in (S/N=55.7)

Improvement of S/N more than 10times Extract signal corresponding to modulation frequency

Reduce noise not related to the frequency

Thermal lock-in High sensitivity with heat conduction information

Confidential 44

Amplitude/Phase & Frequency Effect

0.1Hz 12.5Hz

Frequency dependence of thermal emission from DRAM for PC (Amplitude image)

2.5Hz 0.5Hz

Lock-in frequency

Amplitude image

Phase image

30sec 60sec 120sec 300sec

Accumulation time

Comparison of amplitude and phase image of resistor heated in mold

Sometimes phase image better, positioning by suppress heat expansion

Confidential 45

40sec accumulated without lock-in Lock-in: frequency = 1Hz Lock-in: frequency = 20Hz

Optimizing lock-in frequency Narrowing down to heat position

Frequency Optimization & Phase Analysis

Amplitude image Phase image

(1)

(2)

(3)

(1)

(2)

(3)

Am

plit

ud

e

Phase

t

Signal

Phase delay

t

t

(1)

(2)

(3)

(1)(2) : heat appear early (1) or (2): origin of heat [(1) and (2) may related each other.] (3) : heat phase delayed (3): signal from transmitted heat to chip edge

Phase information Analyzing timing of heat appearance or transmission

Need set suitable frequency & phase information heat conduction

Exemple of Thermal Emission on HEMT AlGaN/ GaN (Source : Thesis M.BOUYA –Université Bordeaux1 - July 2010)

Thermal Image Hot Spots ( circle ) . The others emissions sources outside from active

area are related to the thermal dissipation inside the component.

Confidential 49

The Newest PHEMOS

Install newly designed optics and multi detectors for effective analysis

Macro lens 10 lens turret

Photo emission detector

Thermal emission detector Laser scanning unit

PM8DSP POWER （3kV）

High Voltage probe arm Double side probing

Bias high voltage from Chuck

High power Double Side Prober

Peripheral system Prober for high power devices

Interface to Physical Analyzer

10um

20um

30um

Peripheral system Laser marker

Conclusion

Electro-Luminescence in Power Devices : a UV to NIR concern for Hot Electrons

Obirch in Power Devices : Choice of Laser wavelength for Interconnection / Shorts FA adressing

Thermal Emission in Power Devices : Hot Spots localization and Temperature measurement

Others Considerations : Spectroscopy and Photoluminescence.

Hamamatsu solutions : a Modular and/or a Multimodalities approach

Hamamatsu target : Share our FA applications knowledge for Power devices domain in Europe

THANK YOU VERY MUCH FOR YOUR ATTENTION

Confidential 54

Setup of ESD (Electrostatic Discharge) Experiment

DUT

Photon detection

Time Resolved Imaging Emission Microscope TriPHEMOS

/ Hamamatsu Photonics

Compact ESD Tester HCE-5000 (custom made)

/ Hanwa Electronic Ind.

+ pulse

- pulse

Trigger signal

Emission signal

TRIEM detector controller

Output voltage: 2.5kV Output form: HBM & MM pulse

as infinite loop Loop frequency: 1kHz

ESD operation Too strong emission for TriPHEMOS. ND(Neutral Density) filter in the path to TRIEM detector

to reduce light strength

Applying TRIEM connected to custom made ESD tester for experiment

Confidential 55

TRIEM Application to ESD Observation (1)

Possibility of observation of discharge process using TRIEM technique

Applied waveform Conventional photo emission detection

( without timing information )

Time resolved photo emission detection [ Seems to show electrical discharge as expected by ESD circuit designer ]

Sample: ESD test element ( Single device )

Data courtesy to Renesas Semiconductor Manufacturing Co., Ltd.

10ns

Cu

rren

t (A

)

Time (sec)

HBM (Human body model) pulse: 1000V

Start – 1us 1us – 6us 6us – 8us 8us – 12us

Emission form center of device Decrease of emission once Center concentrated emission ( appear again )

Transition of emission to edge circuit

Confidential 56

TRIEM Application to ESD Observation (2) Data courtesy to Renesas Semiconductor Manufacturing Co., Ltd.

Expected discharge operation is observed in this case also.

Sample: ESD protection circuit

Cu

rren

t (A

)

Time (sec)

MM (Machine model) pulse: 400V

Time resolved photo emission detection

Time resolved photo emission detection [ Circuit A: photo emission in plus current, circuit B photo emission in minus current]

0 20 40 60 80 100 120 140 160 180 200 Time (ns)

Circuit A

Circuit B

Applied waveform

Sample: ESD protection circuit

Confidential 57

To EOP/EOFM Analysis

EOFM image

EOP waveform

Oscilloscope

Spectrum analyzer

Detector

Light source

Perturbation of carrier density

Change of reflective index and light absorption

Variation of reflected light strength and phase

Oscillation of drain potential

Supply gate voltage pattern

FIB/Electron beam

Photo emission Photon incident and reflection

Multi-layer wiring Analysis change from front side

to backside by light detection Mechanism of EOP/EOFM analysis

( using photon incident and reflection )

Impossible to access from front side of device

Difficult to access from front side Backside photon access: EOP/EOFM

Confidential 58

Frequency Range

Input

Output Signal from amplifier Corrected waveform

Waveform observation in low frequency Waveform observation in high frequency Standard system: 10kHz available

New software corrects waveform distortion Sampling rate in high frequency version

Analog: 6GHz, Digital: 25GHz

Sampling rate = 4GHz 250ps time interval Sampling rate = 25GHz 40ps time interval

Waveform to observe (image)

Acquired waveform (image)

4GHz sampling 25GHz sampling

Frequency (Hz) 10k 100k 1M 10M 100M 1G 10G

Waveform correction

Standard system

High frequency version Waveform correction: 2014 October release 25GHz sampling rate: 2014 December release

Data storage: 500,000 points Available to acquire from long loop test vector and expand time axis to detailed waveform check

Expanding frequency range to lower and higher for each application

Confidential 59

Low Frequency Signal Detection Sample: Audio amp. (SOI)

320kHz

Normal operation

Abnormal operation No activity (failing analog block)

Missing analog block can be quickly identified using EOFM image

Confidential 60

No Interference Fringe Incoherent light source Coherent light source

Silicon Sub.

Device

Interference

Phase shift Phase shift 0deg. 0deg. 180deg. 180deg.

without interference fringe with interference fringe

Uniform light reflection Distinct recognition every circuit elements

Scanning microscope

image

Confidential 61

Case Study (5)

Element 6

Element 1

Element 3

Element 4

Element 2

Element 5

Signal flow

Element 1

Element 2

Element 3

Element 4

Element 5

Element 6

5ns

Delay Delay

Acquire EOFM image and EOP waveform from 28nm device

Frequency = 400MHz, Acquisition time = 600s (EOFM)/ 16s (EOP)

EOFM image

EOP waveform

Duty change in Element 5 & 6

Rise up delay from Element 5 No delay in fall down waveform

Suggest a defect between Element 4 & 5

at via/wire in PMOS circuit

Data transfer analysis in 28nm test chip