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 [email protected] www.atotech.com
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