Optimized Cu plating in fan-out wafer-level packaging

MultiPlate: a turnkey solution

Cassandra Melvin Global Product Manager, Advanced Packaging

Outline

1. Global megatrend IoT

2. Fan-out wafer-level packaging

3. Challenges for the electroplating process

4. Optimized Cu plating for pillar

5. MultiPlate’s key technology features

6. Technical summary

Global megatrend IoT Fan-out wafer-level packaging

Global megatrend: Internet of Things (IoT)

PAST Today

Future?

What will be next?

Things have changed!

Smartphones

Connected TVs Wearable

SMART Home • Entertainment • Comfort

Industry • Energy • Efficiency

Auto • Safety • Environment

City • Security • Traffic

Me • Health • Wellness

IoT in Numbers

2015 2020 2050

Connected Sensors

per person 1.4 12 130+

Sensors 10 billion 100+ billion 1+ trillion

World population 7.2 billion 7.8 billion 9.7 billion

Connected Devices 50 billion 25 billion 100+ billion

Next generation mobile devices

require new packaging

technologies

Source: Gartner 2015 McKinsey 2015

Fan-out packaging: growth and manufacturers

300 mm wafers 2015 2016 2017 2018 2019 2020

Total wafer output M/a 0.100 0.700 1.300 1.850 2.45 2.900

RDL runs M/a 0.200 2.400 4.292 5.812 7.442 8.500

Pillar runs M/a 0 0.500 0.900 1.200 1.550 1.600

Tall pillar runs M/a 0 0.500 0.900 1.200 1.55 1.600

Source: Prismark

Source: Yole

1st

Qtr$891M2017

50%

18% 9%

23%

Key packaging technology for next generation mobile devices

eWLB and similar technologies used in automotive applications

Fan-out packaging: key drivers

Improved thermal and electrical performance

More functionality via integration

Smaller form factor

Higher I/O count with more RDLs

FLIP

CH

IP

FAN-OUT BENEFITS

Performance Functionality Size

Next generation challenges for ECD Cu

Next generation challenges for ECD Cu

High current density plating >20 ASD of thick Cu >200 µm Plating high aspect ratios, up to 4:1 for tall pillar Very low organic co-deposition for minimized voiding Low non uniformity for high yield

Requirements for Cu Pillar

Fine line plating of sub 10 µm L/S Conformal RDL plating and via filling with one process Low internal stress to reduce warpage Very low organic co-deposition for minimized voiding

Requirements for Cu RDL

Optimized Cu plating for pillar

Challenge: high speed plating of thick Cu Plating results for 215x200 µm Cu pillar

Customer A Target

Atotech Sampling

Cu Thickness 215 µm

WIW NU 4 %

WID COP 9 µm

WID NU 2 %

TTV 30 µm

Total time 48.25 min

Dep rate 4.4 µm/min

Temp RT

Faster deposition, better uniformity, better co-planarity than customer POR

4.4 µm per minute (20 ASD) proven for 215x200 µm pillar

Diameter: 200 µm

Resist height: 240 µm

Plating height: 215 µm

Process Step 1 Step 2 Step 3

Plating time

Challenge: high speed plating of thick Cu Excellent uniformity for 220x200 µm Cu pillar

Customer B Target

Atotech Sampling

Cu Thickness 220µm 245 µm

WIW NU < 5% 3.3 %

WID COP < 25 µm 12 µm

WID NU < 5 % 2.5 %

TTV < 40 µm 39 µm

TIR < 15 µm 7 µm

Total time 55 min

Dep rate 4.4 µm/min

Temp 25 °C

Process Step 1 Step 2 Step 3 Step 4

Plating time

120 sec

720 sec

1810 sec

642 sec

Superior uniformity performance compared to customer POR

4.4 µm per minute (20 ASD) proven for 220x200 µm pillar

Flow simulation MultiPlate @ 100% velocity Comparison: Diffusion speed = green Convection speed = red

Low AR tall pillar Diameter: 200 µm Resist height: 240 µm Plating height: 215 µm

High AR tall pillar Diameter: 45 µm Resist height: 200 µm Plating height: 180 µm

Challenge: high speed plating of high AR thick Cu Diffusion versus convection plating speed in high AR structures

Challenge: high speed plating of high AR thick Cu Promising results on 180x45 µm tall Cu pillar; development still on-going

Customer C Target

Atotech Sampling, Current Status

Cu Thickness 180 µm 165 µm

WIW NU < 5% 9 %

WID COP < 10 µm 7 µm

TTV ≤ 50 µm 50 µm

10 Step Recipe Process

High Cu VMS (70/70/50)

Total time 43 min

Dep rate 4.4 µm/min

Temp

Sampling showed promising results plating high AR tall pillar in MultiPlate

R&D status for 4.4 µm per minute (20 ASD) on 180x45 µm pillar

Challenge: very low organic co-deposition Results show lower co-deposition at significantly higher current densities

C.D. [ASD]

Depth [nm]

Elements [ppm] Total [ppm] C O S Cl N

MultiPlate + Spherolyte

Cu MP

25

60

0 –

10

00

73 29 7 3 250 362

40 43 29 7 18 372 469

Standard Tool +

Electrolyte

5 148 83 43 119 1068 1461

10 221 86 68 222 1576 2173

Faster plating leads to higher throughput, lower voiding to better reliability

ToF-SIMS measurement shows 75% lower co-deposition at 4-5X faster plating

Challenge: very low organic co-deposition Influence of organic co-deposition after thermal annealing; 30 min at 400°C

Low organic co-deposition

Standard organic co-deposition

ToF-SIMS: total organic ~2000 ppm ToF-SIMS: total organic ~ 400 ppm

Organic co-deposition results in microvoids that impact electrical performance

ToF-SIMS measurement shows very low co-deposition

Challenge: very low organic co-deposition Voiding performance after storage test; post reflow, T = 150 °C, t = 250h

7 ASD in MultiPlate 10 ASD in MultiPlate 25 ASD in MultiPlate

10 ASD in standard tool & process

Faster plating leads to higher throughput, lower voiding to better reliability

Consistent low voiding at higher current densities

Challenge: very low organic co-deposition Two additive system and reverse pulse plating enables pure Cu deposits

Absence of strong levelers leads to less co-deposition and fewer voids

Optimize the profile shape with physical parameters, not strong levelers

Challenge: low non uniformity for high yield Segmented anodes and programmable agitation enable substrate movement

Ave Pillar Height

18.8 µm

Ave WIP 4.26%

Ave WID 1.23%

WIW 8.4%

Ave Pillar Height

19.4 µm

Ave WIP 3.3%

Ave WID 0.8%

WIW 3.5%

Tool without agitation technology Tool with programmable agitation

Resulting in improved uniformity and superior filling of high AR features

Substrate movement during plating ensures optimized agitation and flow

Challenge: low non uniformity for high yield Non uniformity results for 50 µm pillar, 300 mm wafer

Tool Chemistry C.D.

[ASD] Havg [µm]

WIW [%]

WIDavg [%]

WIPavg [%]

MultiPlate Atotech RP 20 19.4 3.5 0.8 3.3

Fountain Plater Standard DC 20 19.1 8.0 4.5 2.2

Fountain Plater Type B

UF2 DC 20 18.1 22.0 3.5 1.5

Non uniformity criteria [%]

WIW 5

WID 5

WIP 5

* Measurement device: confocal laser scanning microscope

Measurement* Position Wafer Die

Better uniformity performance enables higher reliability and yield

Significantly better WIW and WID non uniformity at same current density

MultiPlate’s key technology features

MultiPlate Enabling features for next generation technologies

High Speed Plating

Best in Class Uniformity

Excellent Voiding Performance

High Purity Metal Deposition

Double Side Plating Capability

Thick Metal Plating

Advanced fluid flow delivery

• Optimal uniformity at high deposition rate • Thick and pure metal depositions • improved voiding performance

Segmented, stable anodes

• Adjustable current distribution for: • Best uniformity performance • Long term process stability

Free programmable agitation

• Excellent uniformity at highest plating speeds • Thick and pure metal depositions • Improved voiding performance • PATENT PENDING

Iron redox auxiliary

• Longer, more stable bath life • Lower additive consumption • Better voiding results • Longer anode life • PATENTED

Pulse plating capability

• High speed plating • Pure and thick Cu depositions • Improved voiding performance • Adjustable pillar shape

Modular design

• Easy maintenance • Quick access to subunits • Easy extendibility and customization

MultiPlate Overview of key technology features

Technical summary

Technical summary MultiPlate delivers clear technical advantages

Optimized process for high speed plating of high AR tall pillars

– Current densities >20 ASD for >200 µm Cu pillars with 4:1 AR

Reverse pulse plating and 2 additive system enable:

– 75% lower organic co-deposition at 4-5x faster plating for optimized reliability and throughput

– Significantly lower WIW/WID non-uniformity at higher current densities as compared to industry standard PORs

Technical summary MultiPlate delivers clear technical advantages

Freely programmable agitation enables customizable substrate movement during plating

– Enables optimized agitation and flow, resulting in lower non-uniformity

Plating parameters enable adjustable pillar profile using physical parameters, not strong levelers

– Absence of strong levelers leads to less co-deposition and fewer voids

Parameter A Parameter B Parameter C

MultiPlate enables pure and uniform Cu deposition for high AR tall pillar

Thank you! CONTACT:

Cassandra Melvin

Atotech Deutschland GmbH Erasmusstraße 20 10553 Berlin – Germany

+ 49 (0) 30 349 85 0 cassandra.melvin@atotech.com www.atotech.com