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? Things have changed! What will be next? Home Entertainment Comfort Industry Energy Efficiency SMART Auto Safety Environment City Security Traffic Connected TVs Wearable Smartphones Me Health Wellness
IoT in Numbers 2015 2020 2050 Source: Gartner 2015 McKinsey 2015 World population 7.2 billion 7.8 billion 9.7 billion Connected Devices 25 billion 50 billion 100+ billion Next generation Sensors 10 billion 100+ billion mobile devices 1+ trillion require new packaging Connected technologies Sensors per person 1.4 12 130+
Fan-out packaging: growth and manufacturers 18% 9% 23% $891M 2017 50% 1st Qtr Source: Prismark 300 mm wafers 2015 2016 2017 2018 2019 2020 Key packaging technology for next generation mobile devices Total wafer output M/a 0.100 Source: 0.700 Yole 1.300 1.850 2.45 2.900 RDL runs M/a 0.200 2.400 4.292 5.812 7.442 8.500 ewlb and similar technologies used in automotive applications 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
FLIP CHIP Fan-out packaging: key drivers Improved thermal and electrical performance Higher I/O count with more RDLs More functionality via integration Smaller form factor FAN-OUT BENEFITS Performance Functionality Size
Next generation challenges for ECD Cu
Next generation challenges for ECD Cu Requirements for Cu Pillar 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 RDL 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
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 Process Step 1 Step 2 Step 3 Plating time Diameter: 200 µm Total time 48.25 min Dep rate Temp Resist height: 240 µm Plating height: 215 µm 4.4 µm/min RT 4.4 µm per minute (20 ASD) proven for 215x200 µm pillar Faster deposition, better uniformity, better co-planarity than customer POR
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 Process Step 1 Step 2 Step 3 Step 4 Plating time 120 sec 720 sec 1810 sec 642 sec Total time 55 min Dep rate 4.4 µm/min Temp 25 C 4.4 µm per minute (20 ASD) proven for 220x200 µm pillar Superior uniformity performance compared to customer POR
Challenge: high speed plating of high AR thick Cu Diffusion versus convection plating speed in high AR structures 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 Flow simulation MultiPlate @ 100% velocity Comparison: Diffusion speed = green Convection speed = red
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 R&D status for 4.4 µm per minute (20 ASD) on 180x45 µm pillar Sampling showed promising results plating high AR tall pillar in MultiPlate
600 1000 Challenge: very low organic co-deposition Results show lower co-deposition at significantly higher current densities MultiPlate + Spherolyte Cu MP Standard Tool + Electrolyte C.D. [ASD] 25 Depth [nm] Elements [ppm] C O S Cl N Total [ppm] 73 29 7 3 250 362 40 43 29 7 18 372 469 5 148 83 43 119 1068 1461 10 221 86 68 222 1576 2173 ToF-SIMS measurement shows 75% lower co-deposition at 4-5X faster plating Faster plating leads to higher throughput, lower voiding to better reliability
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 ~ 400 ppm ToF-SIMS: total organic ~2000 ppm ToF-SIMS measurement shows very low co-deposition Organic co-deposition results in microvoids that impact electrical performance
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 Consistent low voiding at higher current densities Faster plating leads to higher throughput, lower voiding to better reliability
Challenge: very low organic co-deposition Two additive system and reverse pulse plating enables pure Cu deposits Optimize the profile shape with physical parameters, not strong levelers Absence of strong levelers leads to less co-deposition and fewer voids
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% Tool without agitation technology Ave Pillar Height 19.4 µm Ave WIP 3.3% Ave WID 0.8% WIW 3.5% Tool with programmable agitation Substrate movement during plating ensures optimized agitation and flow Resulting in improved uniformity and superior filling of high AR features
Challenge: low non uniformity for high yield Non uniformity results for 50 µm pillar, 300 mm wafer Measurement* Position Wafer Die Tool Chemistry C.D. [ASD] H avg [µm] WIW [%] WID avg [%] WIP avg [%] Non uniformity criteria [%] 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 WIW 5 WID 5 Fountain Plater Type B UF2 DC 20 18.1 22.0 3.5 1.5 WIP 5 Significantly better WIW and WID non uniformity at same current density Better uniformity performance enables higher reliability and yield * Measurement device: confocal laser scanning microscope
MultiPlate s key technology features
MultiPlate Enabling features for next generation technologies High Speed Plating Thick Metal Plating Best in Class Uniformity High Purity Metal Deposition Excellent Voiding Performance Double Side Plating Capability
MultiPlate Overview of key technology features Advanced fluid flow delivery Optimal uniformity at high deposition rate Thick and pure metal depositions improved voiding performance Free programmable agitation Excellent uniformity at highest plating speeds Thick and pure metal depositions Improved voiding performance PATENT PENDING Segmented, stable anodes Adjustable current distribution for: Best uniformity performance Long term process stability 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
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 nonuniformity at higher current densities as compared to industry standard PORs
Technical summary MultiPlate delivers clear technical advantages Plating parameters enable adjustable pillar profile using physical parameters, not strong levelers Parameter A Parameter B Parameter C Absence of strong levelers leads to less co-deposition and fewer voids Freely programmable agitation enables customizable substrate movement during plating Enables optimized agitation and flow, resulting in lower non-uniformity MultiPlate enables pure and uniform Cu deposition for high AR tall pillar
CONTACT: Thank you! Cassandra Melvin Atotech Deutschland GmbH Erasmusstraße 20 10553 Berlin Germany + 49 (0) 30 349 85 0 cassandra.melvin@atotech.com www.atotech.com