tools dedicated to chip access - · pdf filetools dedicated to chip access 1 . dc in summary...

François KERISIT

2014 October,16 Rouen, France

Confidential

Tools dedicated to chip access

1

DC in summary • President : Véronique POULAIN • Founder : Michael OBEIN

• Specialization : IC Decapsulation (20+ years)

• R&D : Worldwide

• Manufacturing : FabLess since 2002

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FA FLOW

Fig. 9

423

Fig. 9

423

Decapsulation is the beginning

of the Flow just after electrical

and visual inspection !!!

Without a good decapsulation :

No analysis.

From Peter JACOB - EMPA

…

3

Why open a component?

Make the chip visible

Front side

Back side

Make bondings accessible

See all connections

Find contaminants

…

4 usual techniques are possible in this day but

depend on purpose Picture property : LaMIP NXP CAEN / DIGIT CONCEPT

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4 MAIN WAYS CHIP ACCESS

4 MAIN WAYS

MECHANICAL CAN OPENER

MICROABRASIV

E BLASTING

SsameSiPrep

DIP OPENER

LASER

SesameLASER

SesamePLASMA

and PLASER

PLASMA

ACIDS SesameACID

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4 MAIN WAYS : 1/4

1- LASER INTRODUCTION

OR FIBER LASER

2004 2012

2014

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LASER Exemples 1/23

Confidential 8

LaMIP Schwindenhammer Patrice

Functional Decapsulation! for FA :

chemical + laser

BGA high pin count exposure

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LASER Exemples 2/23

Confidential

Goal:

Remove nearly all EMC above or

below the chip (front side or

backside). Around 100µm

remaining EMC thickness allows

better result for SQUID or for

thermograph investigations.

Benefits:

Safe, fast, repeatable.

Very useful when chips are not

chemical compatible.

Preparation for MAGNETIC/THERMAL

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LASER Exemples 2/23

Confidential

Power Package Goal:

Reach both dies without

separating them, without damage

on Cu wires and without acid leak.

Methodology:

1. LASER cavity.

2. Wet chemical opening at low

temperature.

Benefits:

Safe, fast, repeatable.

Allow low temp wet chemical

opening in a reasonable time.

Decrease acid consumption.

No acid leak.

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LASER Exemples 4/23

Confidential

Glass cover removal Goal:

Remove easily a glass cover.

Methodology:

1. Vaporization of the glue with

LASER (glass cover is

1064nm fully transparent).

2. Cover removal is then very

easy with a blade.

Benefits:

Safe, fast, repeatable.

No thermal stress.

Necessary to do a sample

cleaning with acetone to remove

projected glue particles.

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LASER Exemples 5/23

Confidential

Goal:

Observe, remove or replace a

SMD in a SIP.

Methodology:

EMC removal with LASER.

PCB and SMD are not damaged

during LASER process.

Benefits:

Safe, fast, repeatable.

No use of chemicals.

Small size opening allowed.

Passive component removal (SIP)

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LASER Exemples 6/23

Confidential

Die paddle removal Goal:

Remove rapidly die paddle to have

a backside access.

Methodology:

1. EMC removal all around the die

paddle.

2. Die paddle removal with a

blade.

Benefits:

Safe, fast, repeatable.

No scratch on die backside.

Easy glue removal with acetone.

Not useable on thick die paddle.

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LASER Exemples 10/23

Confidential 20 LaMIP - Schwindenhammer Patrice 2006-01-23

Cut bond wires

The ~40 µm spot laser is thin enough to precisely perform a surgical cut of a single wire without preliminary de-capsulate the package

Remark : Laminates copper tracks can be cut in a same way

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LASER Exemples 12/23

Confidential 20 LaMIP - Schwindenhammer Patrice

Decapsulation on Module Silicon Tuner

Decapsulation on board

Decapsulation on Board is done in two steps : - chemistry + laser for packages - laser + chemistry for globe top

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LASER Exemples 15/23

Confidential

Bond Pads

Expose Individual Bond Pads

Locate Failed Bonds

Find Broken Wires

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LASER Exemples 17/23

Confidential

Laser Cross-Sectioning Solder Ball Cross-Sections

IC Cross-Sections

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LASER Exemples 18/23

Confidential 18

LASER Exemples 19/23

Confidential

Gel Removal Down to the Die Remove Gel Compound in seconds rather than

hours and days with Acid Processing

Before Gel Removal After Gel Removal

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LASER Exemples 20/23

Confidential 20

LASER Exemples 21/23

Confidential

Large Filler Mold Compounds for Copper

We’ve developed a patent pending technique for

removing the newer mold compounds associated

with copper wires and bonds

Large, Difficult to Remove Fillers Our New Process Removes them Easily

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LASER Exemples 23/23

No other wavelength/pulse duration/pulse shape

was able to process this part

LASER before FIB

Removing Stacked Die

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4 MAIN WAYS : 2/4

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MECHANICAL Exemples 1/2

Confidential Pictures property : THALES / DIGIT CONCEPT

Micro-Milling machine equipped with collimator

Package

Chip Coating Die Topside

Back Side Hole

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MECHANICAL Exemples 2/2

Confidential 25

4 MAIN WAYS : 3/4

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ACIDES INTRODUCTION

Confidential

Auto–decapper with Peltier element for cooling to 10°C

Redesigned pump for more turbulent flow [4]

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ACIDES Exemples 1/8

Confidential

LaMIP - Schwindenhammer Patrice

Example of a RF Module - MANUAL die exposure using Silicone polymer protector and Nitric acid (pipet) 100°C on heater.

Manual chemical decapsulation and its help/limitations

silicone

• It is hard only with chemistry to expose all bondings.

• It is also hard using only chemistries to expose BGA

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Confidential

Part 1: Laser Pre-decapsulation

1st removed EMC above die and stitch

bonds until tops of wire loops exposed

2nd ablation step performed with

exclusion zone above die

Cannot expose die by laser, stitch bonds

no problem

Laser pre-cavity can reduce acid etch

time by half [1]

All samples in temperature study pre-

decapsulated using same auto program

[1] Klein, et.al, 2010 ISTFA Proceedings

Pre-cavity after 1st ablation step above die and stitch areas

Pre-cavity after 2nd ablation step with trench around die

ACIDES ISTFA2011 2/9

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Confidential

Part 2: Chemical etch Low temperature (10°C – 44°C) to reduce acid attack

Use of monolithich gasket to ensure tight seal

3:1 Nitric / Sulfuric acid mixture

Etch until die and in some cases stitch bonds fully exposed

LEFT: Monolithic rubber gasket cut by laser for QFP

ACIDES ISTFA2011 3/9

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Confidential

Acetone

Hot water (70°C – 100°C) bath for ~1 minute

Isopropanol

N2 dry

SEM photo of Cu wire cross section after decapsulation by nitric/sulfuric acid mix. In this case the hot water rinse was not used and the resulting crystal growth analyzed by EDX. Evidence of cupric sulfate on surface.

Part 3: Rinses

ACIDES ISTFA2011 4/9

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Confidential

44°C for 40s

No observable attack or corrosion on the lead finger

coating or die pads, wires very uniform with a

measured diameter of ~19.5mm and no evidence of

thinning or pitting.

Al coating removed from lead fingers, acid attack

visible on Cu wires with measured diameters of

14-19mm.

Temperature study #1

10°C for 270s

Package type: LQFP 64 with Sumikon G631H resin

0.8 mil (~20mm) Cu wires with Al coated Cu lead fingers and Al pads

Acid etch performed at 44°C, 27°C, 15°C, and 10°C

ACIDES ISTFA2011 5/9

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Confidential

Temperature studies: Summary

Temperature Etch time

TBGA

(8 x 8mm)

QFP

(14 x 14mm)

BGA

(23 x 23mm)

44°C 20s 40s 80s

27°C 60s 100s 120s

15°C 75s 200s 160s

10°C 90s 275s 190s

ACIDES ISTFA2011 9/9

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ACIDES Exemples 7/8

Confidential

Optical micrograph showing a Cu wire after acid etch using a HNO3:H2SO4 mixture @ +10°C. The coating of the surface of the die (BCB) is without damage.

Chip coating Polyamide and

benzo-cyclo-butene (BCB)

low-k dielectric

Cu traces and BCB

removed

Residual organic

passivation After standard chemical etch at 80°C,

20°C using a 5:1 mixture of HNO3 and H2SO4

3:1 HNO3 to H2SO4 mixture at 10°C for 120s.

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4 MAIN WAYS : 4/4

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PLASMA INTRODUCTION

Confidential EDFAS USA, Golden Gate Chapter, Setember 9, 2010

SESAME Technology

incorporates Mutual

Patents / IP developed by

CNES,

DIGIT CONCEPT SA

(WO2008/090281)

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A : LASER Ablation

• STEP 1 : Place your component on XY table

• STEP 2 : Importation of an X-ray or CSAM image

• STEP 3 : Adjust X and Y with the Table

• STEP 4 : Choose your recipe

• STEP 5 : Start LASER Ablation

PLASMA INTRODUCTION

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B : LASER/Plasma Ablation

Only with Sesame2000 • Decrease of power LASER

• Increase of power PLASMA

• The hard coating is removed

PLASMA INTRODUCTION

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Plasma O2/CF4

Plasma for 15mn

Blast 2 seconds

PLASMA INTRODUCTION

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PLASMA Examples 1/4

Confidential

BCB/Cu Goal:

Reach circuitry without degradation

(BCB dielectric , Cu lines).

Methodology:

1. LASER cavity.

2. Dry chemical (PLASMA) opening.

Benefits:

No degradation due acid use.

EDFAS USA, Golden Gate Chapter, Setember 9, 2010

LAT

STM TOURS

FRANCE

40

LASER decapsulation: Plastic ablation down to passive die backside (Si).

Plasma etching (Ar then SF6): Silicon etching down to passive die backside.

Wet & dry etching, down to underfill.

Wet chemical (HNO3) underfill etching down to active die.

Xrays analysis, zoom on active die: No visible damage on 1st and 2nd interconnects.

LASER / Plasma / Acid …

2D / 3D

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Papers about these techniques from DC

CONFIDENTIAL

• …

• EPTC 2006

• ANADEF 2006

• ESREF 2007

• ANADEF 2008

• ESREF 2008

• ISTFA 2008

• ANADEF 2010

• IPFA 2010

• ESREF 2011

• ISTFA 2011

• EPTC 2011

• IMAPS 2012

• ISTFA 2014

• …

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One-shot acid decapsulation :

• Etch time : 1000 s

• Die is fully exposed

• Several rinse baths : acetone, hot water and alcool

• wires preserved, though wire surface is slightly attacked

2:1, 10°C

Copper wire – acid low T°

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• Electrolysis

– 10V

– 35°C, 2:1

– 3x180s

– multi-step possible

Copper wire - Electrolysis

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[4] Nisene, US Patent 20130082031

• Dry chemistry parameters

• Total etch time : 3 to 4 hours.

• Final acetone rinse in ultrasonic bath was needed to remove residues on die surface.

Process T (°C) %CF4 %O2

Fast 25 40 60

Slow 25 10 90

50W, 25°C

Ball-bond and wire surface are much more preserved with plasma than with acid etching.

Furthermore, the electrical functionality of the opened devices was also checked before photoemission microscopy analysis, which could be successfully performed.

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Copper wire – Plasma

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Ag wire decapsulation

[5] Kerisit et.al, 2014 ISTFA Proceedings

acid 2:1, 10°C plasma 100W, 80°C plasma 50W, 80°C

plasma 50W, 25°C • Total etch time of 200 minutes to completely expose the die

• Very long duration for a single sample

• Step by step procedure with a precise control over the etching.

Results Etch time Electrical influence

Cu acid low T° Good Slow None

Cu acid electrolysis

Good Fast Possible

Cu plasma Good Very slow possible

Ag acid low T° Broken wires Slow None

Ag acid electrolysis

Not tested Fast Possible

Ag plasma Good Very slow Possible

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Summary

Thank you.

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