11

PositivePositive--Tone Photosensitive Polyimide CoatingsTone Photosensitive Polyimide Coatingsfor Lens Layer in image sensorsfor Lens Layer in image sensors

““PhotoneecePhotoneece”” CSCS--seriesseries

Toray Industries, Inc.

Introduction of the characteristic of CS-series

22

Thickness ：0.3μm～1.2μmResolution：Aspect ratio=3Application：［Inner lens］

［On-chip lens］

Aqueous developable positive tone PSPI (Photo Sensitive Polyimide) with high R.I., good chemical resistance and high resolution.

（１）High Refractive Index（２）Excellent Chemical Stability （３）High resolution（４）Tough product quality（５）Aqueous developable with 2.38% TMAH

CS-7500 basic properties

<Current specs >

33

CS-series have the suitable characteristics for lens layer in Image Sensors

0

1

2

3

4

5

Patternability

Transparency

Refractive Index

ShapeThermal stability

Adhesion strength

Liquid stability

Acrylic Inorganic CS-series

CS-7500 vs. Other Materials

44

Measurement methodMeasurement method：：Prism couplerPrism couplerCure ConditionsCure Conditions：２８０℃：２８０℃××５５minmin（（AirAir、、hotplate)hotplate)

＜R.I. Dependency on wavelength>

CS-7500 basic properties

Wavelength R.I.400 1.81450 1.80500 1.80600 1.79

1.7

1.74

1.78

1.82

1.86

1.9

350 450 550 650

Wave length（ｎｍ）

Reflecti

ve Inde

xR

efra

ctiv

e In

dex

55

0

20

40

60

80

100

120

200 300 400 500 600 700 800

wavelength （ｎｍ）

T　 （％

）<Dependency of transparency on wavelength (@thickness 1μm)>

CS-7500 basic properties

Measurement apparatusMeasurement apparatus：：Shimadzu UVShimadzu UV--180180Curing conditionsCuring conditions：：300300℃×℃×５５min(hotplatemin(hotplate)*)*

*Air curing（In case of N2 cure, Transparency=90%/1um@400nm)

Tran

spar

ency

(%)

66

0

10

20

30

40

50

60

70

80

90

100

300 400 500 600 700 800

wavelength (nm)

T (

%) as depo

250℃ 1min (HP, in air)

300℃ 1min (HP, in air)

Transparency maintains after heat treatment.

Effect of thermal treatment on its transparencyTr

ansp

aren

cy (%

)

77

Curing conditionsCuring conditions(Hot plate)(Hot plate)

２００℃２００℃××５５minmin

２２０℃２２０℃××５５minmin

２５０℃２５０℃××５５minmin

２８０℃２８０℃××５５minmin

R.I.R.I.（（632nm)632nm)

Transparency Transparency （（%/1um)%/1um)500nm500nm400nm400nm 700nm700nm

1.791.79

1.801.80

1.761.76

1.791.79 9393 9797 9898

9393 9898 100100

9393 9797 100100

8585 9595 9898

<Curing conditions vs Refractive Index>

CS-7500 basic properties

88

Pattern profile (after curing)

Allay pattern (2.0μm / 0.25μm) L / S pattern (1.0 / 1.0μm)

HMDS treatment 60℃×20secSpin 700rpm×10 sec and 1700rpm×120secPre bake 120℃×3min @hot plate (thickness 0.87um)Exposure1 650msec (i-line stepper, Focus=0um) : for patterningDevelopment 70 sec. Puddle development @ 2.38% TMAH sol. (thickness 0.65um)Cure 280℃×5min @hot plate (thickness 0.55um)

99

Pattern profile (thiner film, after curing)

HMDS treatment 60℃×20secSpin 700rpm×10 sec and 1500rpm×120secPre bake 120℃×3min @hot plate (thickness 0.47um)Exposure1 160msec (i-line stepper, Focus=0um) : for patterningDevelopment 30 sec. Puddle development @ 2.38% TMAH sol. (thickness 0.39um)Exposure2 0.1～0.5 J/cm2（broad band @ i-line) : for bleachingCure 300℃× 5min @hot plate (thickness 0.32um)

2um line / 2um space (thickness 0.32um)

1010

Patterning Process of CS-7500

<Film thickness after cure:0.7μm recipe example>

HMDS 60℃×20sec

Spin 1500rpm for 120sec

Prebake 120℃×3min (Hot plate) (Thickness 1.00μm）

Exposure1 400 msec (i-line stepper, Focus=0μm)：For patterning

Development 50 sec. Puddle development (Thickness 0.85μm）

（2.38％TMAH solution）

Exposure2 0.1～0.5 J/cm2（broad band @ i-line)：For bleaching

Cure* 280℃× 5min (Hot plate ) (Thickness 0.70μm）

**Curing Temp. range from 2Curing Temp. range from 22200℃℃ to 300to 300℃℃

1111

Patterning Process of CS-7500

< Sensitivity curve >

01020

3040506070

8090

100

1 10 100 1000

Exposure time (msec)

Norm

aliz

ed

thic

kness

(%)

HMDS treatment 60℃×20secSpin 1500rpm×120secPre bake 120℃×3min @hot plate (thickness 1.00um)Exposure i-line stepper, Focus=0umDevelopment 50 sec. Puddle development @ 2.38% TMAH sol. (thickness 0.85um)

1212

Patterning Process of CS -7500

<Film thickness after cure:0.8μm recipe example>

HMDS 60℃×20sec

Spin 700rpm for 10 sec and 1500rpm for 30sec

Prebake 120℃×3min (Hot plate) (Thickness 1.21μm）

Exposure1 300 msec (i-line stepper, Focus=0.5μm)：For patterning

Development 50 sec. Puddle development (Thickness 1.03μm）

（2.38％TMAH solution）

Exposure2 0.1～0.5 J/cm2（broad band @ i-line)：For high transparency

Cure* 280℃× 5min (Hot plate ) (Thickness 0.84μm）

※※Cure ranges from 2Cure ranges from 22200℃℃ to 300to 300℃℃

1313

<Pattern process recipe by Mark-7>

Patterning Process of CS-7500

１． PI Coating (Mark 7)C/S

Coater recipe（Manual）

↓ STEP Time Speed Acceleration Dispense Arm ArmＨＭＤＳ (HP) 60℃ X 20 s (sec) (rpm) (rpm/sec) 1 2

↓ 1 10.0 50 1000 1 Home HomeCOL 23℃ X 60 s 2 5.0 0 1000 0 Home Home

↓ 3 10.0 700 2000 0 Home HomeCOAT 4 120.0 1500 1000 0 Home Home↓ 5 2.0 0 1000 0 Home Home

Pre-Bake (HP) 1 20℃ X 180 s Dispense CS-7000 at step 1↓

COL 23℃ X 60 s↓

C/S

２．Exposure1Ｉ-line stepper（GCA 8000 DSW WAFER STEPPER）

ET 300 msec (150mJ/cm2)

Development recipefocus 0.5μm

STEP Time Speed Acceleration

(sec) (rpm) (rpm/sec)３．Development (Mark 7)/Bake

1 1.0 1000 10000 0C/S

2 3.0 1000 10000 1 7↓

3 1.0 500 10000 1 7DEV

4 1.0 100 10000 1 7

5 4.0 30 10000 1 76 36.0 0 10000 5

7 5.0 0 10000 58 5.0 500 10000 3 4 99 5.0 2000 10000 3 4 9

10 20.0 3000 10000 0Development（TMAH 2.38%）Rate：0.6 L/min

Rinse（DI water)Rate：1.2 L/minBack rinse（DI water）Rate：150 mL/min

Cup exhaust：60 PaNozzle：Stream nozzleDispense７：Developer dispense

↓C/S

Dispense

5．CureCure machine：Mark-7(TEL)Cure steps：

Atmosphere：N2

4．Exposure２PLA Broadband alighner

Exposure0.1～5J/cm2(at iline）

280℃×5 min → r.t.r.t.→

1414

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

500 1500 2500 3500 4500 5500Rotation speed（X rpm×120sec）

Thic

knes

s afte

r Pre

baki

ng（μ

m）

Spin curve of CS-7500 (example)