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Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Low Temperature Curable Polynorbornene as Redistribution Layer
Sumitomo Bakelite co-authors:Etsu Takeuchi
Junya Kusunoki
Seishi Ohashi
Promerus co-authors:Chris Apanius
Ed Elce
Hendra Ng
Presented by: Brian Knapp, Ph.D.
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Outline
General Characteristics of Avatrel® Photodefinable Polymers
Chemical Structure
Low Shrinkage
Wafer Stress
Planarity
General Imaging
Applications
Redistribution Layer (RDL) Device Build
Reliability Testing
Summary
2008 Symposium on Polymers 2
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Synergies of Chemistry in Polycyclic Polyolefins
2008 Symposium on Polymers 3
Polynorbornene
High Tg From Backbone
Alkyl – Tune Modulus/Stress
Low Moisture Absorption
Isotropic Properties
Transparency
Low Dielectric Constant
Epoxy
Accepted Chemistry
Low Temperature Cure
Adhesion
Photosensitive
Epoxy
R
Alkyl
RR
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Low Film Thickness Shrinkage through Wafer Processing- 1400 rpm, Cyclopentanone develop, 180oC/2h cure
2008 Symposium on Polymers 4
9
9.2
9.4
9.6
9.8
10
10.2
10.4
10.6
10.8
11
SB Exposure PEB Develop Cure
Fil
m T
hic
kn
ess
(mm
)All changes < 1%
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Low Wafer Warpage with Simple Coatings
Wafer: 200 mm Si WaferThickness: 625 mmMeasuring span: 100 mm
2008 Symposium on Polymers 5
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Planarization of Avatrel over Topology
Avatrel has good planarization with dense feature patterns
Planarization is very good for 60 µm thick films on 7 & 15 µm topology, 100% DOP
Planarization is 85 to 96% DOP for 30 µm thick films on 7 µm topology
Planarization is 75 to 82% DOP for 30 µm thick films on 15 µm topology
d = d = a+b+c/3a+b+c/3
aa bb cc
200um200um 200um200um
15um15um
aa bb ccaa bb cc
200um200um 200um200um
15um15um
Avatrel
200um200um10010080807070
62008 Symposium on Polymers
% DOP (degree of planarization) = (1–d/step height) x 100%
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
General Imaging Capability of Avatrel® Polycyclic Polyolefins
2008 Symposium on Polymers 7
63 x 325 mm 150 mm Dice Lanes
2.5 mm lines/spaces 4:1 aspect ratio 70 mm Collars
Single layer: 150 mm vias
Solv
ent
Dev
elo
pab
leA
qu
eou
s D
evel
op
able
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
20mm Avatrel
Silicon Beam
cavity
Avatrel®/Unity® Applications
2008 Symposium on Polymers 8
Photo-
definable
Unity
High
Temperature
Unity
Aqueous
Developable
CIS Dam
ApplicationsBackside
Interconnect
Layer
Transparent
Adhesive
300 µm
Layers
Wafer Level
Packaging
Temporary
Wafer
Adhesive
Wafer Level
MEMS
Packaging
Avatrel/
Unity
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Motivation for Redistribution Materials
A material which aids in the relocation of bond pads
Desirability stems from small package size, high-speed electrical access, and ability to accommodate standard pad layouts
RDL WL-CSP is often used in miniaturized consumer electronic products
Cell phones consume 80-90% of all WL-CSP packages
Redistribution is the most popular WL-CSP>90% of the 6.1 Bn WL-CSP packages shipped in 2007 used RDLs
As processors move to multi-core designs, clock redistribution may be required
2008 Symposium on Polymers 9
Marketing data courtesy of:
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
WPR
PBO
PI
Cure Temperature (oC)400 300 200 100
Processing Shrinkage (%) 40 30 20 10
Water Absorption (%) 1.5 1.0 0.5 0.0
Residual Wafer Stress (MPa) 40 30 20 10
Dielectric Constant (1 MHz) 3.5 3.0 2.5 2.0
Tensile Modulus (GPa) 1.0 2.0 3.0 4.0
Tensile Strength (MPa) 20015010050
Elongation to Break (%) 10 20 30 40
Tg (oC via TMA) 200 250 300 350
CTE (ppm/oC)100 75 50 25
BCB
PI
PI
PI
PI
PI
PI
PI
BCB
BCB
BCB
BCB
BCB
BCB
BCB
BCB
PNB
PNB
PNB
PNB
PNB
PNB
PNB
BCB
PI
PBO
PBO
Property Comparison of Redistribution Materials
2008 Symposium on Polymers 10
PBO
PBO
PBO
PBO
PBO
PBO
*Source: Manufacturer websites
WPR
WPR
WPR
WPR
WPR
WPR
WPR
WPRPI PNB
PNB
PNB
HD-4000
WPR-1201
Cyclotene 4026-46
CRC-8650
Avatrel-RDL
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Process Flow for RDL Device Build
Metal-11a) Passivated Copper Wafers
1b) Coat with Resist
1c) Photo/Etch
Polymer-12) Pattern Layer-1 of Avatrel-RDL
Metal-23a) Copper Seed Layer Deposition
3b) Coat with Plating Resist
3c) Copper Electroplating
3d) Resist Strip and Seed Layer Etch
Polymer-24) Pattern Layer-2 of Avatrel-RDL
Metal-35a) Deposition of Nickel/Gold
5b) Photo/Etch
2008 Symposium on Polymers 11
Subsidiary of Sumitomo Bakelite Co. Ltd.
®
Step 1a: Copper Wafers over Passivation Layer- Copper (5000Å) on SiOx or Si3N4