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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.

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Page 1: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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.

Page 2: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 3: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 4: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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%

Page 5: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 6: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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%

Page 7: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 8: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 9: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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:

Page 10: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 11: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

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

Page 12: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 1a: Copper Wafers over Passivation Layer- Copper (5000Å) on SiOx or Si3N4

2008 Symposium on Polymers 12

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 13: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 1b: Copper Wafer Coated with Resist- Shipley 1813 PT Resist

2008 Symposium on Polymers 13

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 14: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 1c: Metal-1 Patterned with Photo and Cu-Etch- Transene APS-100 Etchant

2008 Symposium on Polymers 14

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 15: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 2: 1st Layer of Avatrel Processed

2008 Symposium on Polymers 15

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 16: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Standard Process for the Imaging of Avatrel® Redistribution Material

Wafer Process Conditions

Dehydration Hydration Bake: 130oC/2 min

Plasma Pretreatment: 50/50 Ar/O2, 300 W, 30 sec

Spin-coat

Prebake: 120oC/5 min

Exposure: 300-800 mJ/cm2

Post-Exposure Bake: 90oC/4 min

Develop: Cyclopentanone, 20 sec

Cure: 180oC/2h

Inducing Sidewall Slope

Proximity

DOF

Polymer

Formulation

2008 Symposium on Polymers 16

Page 17: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 2 Details: Sidewall Imaging in Proximity Mode on Aligner- 300 mJ/cm2 on Copper

2008 Symposium on Polymers 17

Contact Mode

Proximity Mode

30

40

50

60

70

80

90

0 20 40 60 80 100 120

Sid

ewal

l An

gle

(°)

Proximity (µm)

Page 18: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 2 Details: Tunable Sidewall using Depth of Focus on Stepper

2008 Symposium on Polymers 18

60

65

70

75

80

85

90

Depth of Focus (mm)

Sid

ewal

l an

gle

(deg

rees

)

Above the surface Below the surface

84o

78o

81o

77o

86o80o

74o72o

Page 19: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 2: 1st Layer of Avatrel Processed

2008 Symposium on Polymers 19

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 20: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 3a: Deposited Conductive Seed Layer for Electroplating- Sputtered Copper, 1000Å

2008 Symposium on Polymers 20

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 21: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 3b: Patterned Metal-2 with Plating Resist- AZ 9260: Thick Film, Positive-Tone

2008 Symposium on Polymers 21

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 22: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 3c: Subjected to Copper Electroplating (3-7 mm)

2008 Symposium on Polymers 22

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 23: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 3d: Stripped Resist and Etched Seed Layer- Acetone/IPA, Transene APS-100 Copper Etchant

2008 Symposium on Polymers 23

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 24: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 4: 2nd Layer of Avatrel Processed

2008 Symposium on Polymers 24

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 25: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 5a: Deposited Metal-3 for UBM- Sputtered 3000Å Nickel, 500Å Au

2008 Symposium on Polymers 25

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Top Down

~150 mm

Cross-section

Page 26: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Step 5b: Metal-3 Patterned with Photo/Etch- AZ 9260 Resist, Transene Gold Etch TFA & Nickel Etch TFG

2008 Symposium on Polymers 26

Cross-section

Top Down

~150 mm

150 mm

75 mm

25 mm

Si-waferPassivationCopperPhotoresistAvatrel

NickelGold

Page 27: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

24

23

22

21

20

19

18

17

16

15

14

13

37

38

39

40

41

42

43

44

45

46

47

48

36 35 34 33 32 31 30 29 28 27 26 25

1 2 3 4 5 6 7 8 9 10 11 12

Device Layout on Die (6.3 mm x 6.3 mm)

2008 Symposium on Polymers 27

Metal-1

Metal-2

Metal-3

Page 28: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

SEM Image of Full Device

Metal-1Titanium: 100Å

Copper: 5000Å

Avatrel-110 mm

Metal-2Copper: 4 mm

Avatrel-210 mm

Metal-3Nickel: 3000Å

Gold: 500Å

2008 Symposium on Polymers 28

Page 29: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

SEM Image of Metal-3 Bond Pad

2008 Symposium on Polymers 29

Page 30: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

SEM Image of Buried Metal-2 Copper Trace

2008 Symposium on Polymers 30

Page 31: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

SEM Image of Metal-1 and Metal-2

2008 Symposium on Polymers 31

Page 32: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Reliability Testing

2008 Symposium on Polymers 32

Thermal Cycling (T/C)

-55oC -> 125oC JEDEC 22, A104-A

Thermal Reflow

260oC

Pressure Cooker (PCT)

125oC, 2.3 atm, 100% RH JEDEC 22B, A102-B

High Temperature Storage (HTS)

150oC in air JEDEC 22B, A103-A

Pending

0 Cycles1000500200100

24096480

Hours10004501680

Passed

Cycles 10530

Hours

Page 33: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

90%

95%

100%

105%

110%

115%

120%

CRC-8650 Competitor A Competitor B Avatrel-RDL

No

rmal

ized

Wit

hin

Mat

eria

l Set

0 h HTS 100 h HTS

Stability of Tensile Modulus post-HTS- 150oC in Air

2008 Symposium on Polymers 33

Page 34: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Stability of Tensile Strength post-HTS- 150oC in Air

2008 Symposium on Polymers 34

90%

95%

100%

105%

110%

115%

120%

CRC-8650 Competitor A Competitor B Avatrel-RDL

No

rmal

ized

Wit

hin

Mat

eria

l Set

0 h HTS 100 h HTS

Page 35: Low Temperature Curable Polynorbornene as Redistribution Layer · Low Temperature Curable Polynorbornene as Redistribution Layer Sumitomo Bakelite co-authors: Etsu Takeuchi Junya

Subsidiary of Sumitomo Bakelite Co. Ltd.

®

Summary

Avatrel® Redistribution Material

Thermal Properties: high Tg, good stability

Electrical Properties: low CTE and low dielectric constant

Wafer Properties: low shrinkage and low residual stress

Imaging: thick film, high aspect ratio, tunable sidewall angle

Low Temperature Curability

RDL devices have been successfully fabricated with positive

reliability results

Commercial qualification is ongoing

Aqueous versions are being developed

2008 Symposium on Polymers 35