Positive-Tone Photosensitive Polyimide Coatings for Lens Layer in image sensors Photoneece CS-series Introduction of the characteristic of CS-series Toray Industries, Inc. 1 1
CS-7500 basic properties 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 <Current specs > Thickness :0.3μm~1.2μm Resolution:Aspect ratio=3 Application:[Inner lens] [On-chip lens] 2 2
CS-7500 vs. Other Materials Liquid stability Adhesion strength Patternability 5 4 3 2 1 0 Transparency Refractive Index Thermal stability Shape Acrylic Inorganic CS-series CS-series have the suitable characteristics for lens layer in Image Sensors 3 3
CS-7500 basic properties <R.I. Dependency on wavelength> 1.9 1.86 Reflective Index Refractive Index 1.82 1.78 1.74 1.7 350 450 550 650 Wave length(nm) R.I. 400 1.81 450 1.80 500 1.80 600 1.79 Wavelength 4 Measurement method:prism coupler Cure Conditions:280 :280 5min(Air hotplate) 4
CS-7500 basic properties <Dependency of transparency on wavelength (@thickness 1μm)> 120 100 Transparency (%) T (%) 80 60 40 20 Measurement apparatus:shimadzu UV-180 Curing conditions:300 300 5min(hotplate)* 5 0 200 300 400 500 600 700 800 wavelength (nm) *Air curing(in case of N2 cure, Transparency=90%/1um@400nm) 5
Effect of thermal treatment on its transparency Transparency (%) T (%) 100 90 80 70 60 50 40 30 20 as depo 10 0 300 400 500 600 700 800 wavelength (nm) 250 1min (HP, in air) 300 1min (HP, in air) 6 Transparency maintains after heat treatment. 6
CS-7500 basic properties <Curing conditions vs Refractive Index> Curing conditions (Hot plate) 200 5min 220 5min 250 5min R.I. (632nm) 1.76 1.79 Transparency (%/1um) 400nm 500nm 700nm 93 98 100 93 97 100 1.79 93 97 98 280 5min 1.80 85 95 98 7 7
Pattern profile (after curing) Allay pattern (2.0μm / 0.25μm) L / S pattern (1.0 / 1.0μm) 8 HMDS treatment Spin Pre bake Exposure1 Development Cure 60 20sec 700rpm 10 sec and 1700rpm 120sec 120 3min @hot plate (thickness 0.87um) 650msec (i-line stepper, Focus=0um) : for patterning 70 sec. Puddle development @ 2.38% TMAH sol. (thickness 0.65um) 280 5min @hot plate (thickness 0.55um) 8
Pattern profile (thiner film, after curing) 2um line / 2um space (thickness 0.32um) HMDS treatment Spin Pre bake Exposure1 Development Exposure2 Cure 60 20sec 700rpm 10 sec and 1500rpm 120sec 120 3min @hot plate (thickness 0.47um) 160msec (i-line stepper, Focus=0um) : for patterning 30 sec. Puddle development @ 2.38% TMAH sol. (thickness 0.39um) 0.1~0.5 J/cm2(broad band @ i-line) : for bleaching 300 5min @hot plate (thickness 0.32um) 9 9
Patterning Process of CS-7500 <Film thickness after cure:0.7μm recipe example> HMDS Spin Prebake Exposure1 60 20sec 1500rpm for 120sec 120 3min (Hot plate) (Thickness 1.00μm) 400 msec (i-line stepper, Focus=0μm):For patterning Development 50 sec. Puddle development (Thickness 0.85μm) (2.38%TMAH solution) Exposure2 Cure* 10 0.1~0.5 J/cm2(broad band @ i-line):for bleaching 280 5min (Hot plate ) (Thickness 0.70μm) *Curing Temp. range from 220 2 to 300 10
Patterning Process of CS-7500 < Sensitivity curve > Normalized thickness(%) 100 90 80 70 60 50 40 30 20 10 0 1 10 100 1000 Exposure time (msec) 11 HMDS treatment Spin Pre bake Exposure Development 60 20sec 1500rpm 120sec 120 3min @hot plate (thickness 1.00um) i-line stepper, Focus=0um 50 sec. Puddle development @ 2.38% TMAH sol. (thickness 0.85um) 11
Patterning Process of CS -7500 <Film thickness after cure:0.8μm recipe example> HMDS Spin Prebake Exposure1 60 20sec 700rpm for 10 sec and 1500rpm for 30sec 120 3min (Hot plate) (Thickness 1.21μm) 300 msec (i-line stepper, Focus=0.5μm):For patterning Development 50 sec. Puddle development (Thickness 1.03μm) (2.38%TMAH solution) Exposure2 Cure* 0.1~0.5 J/cm2(broad band @ i-line):for high transparency 280 5min (Hot plate ) (Thickness 0.84μm) 12 Cure Cure ranges from 220 2 to 300 12
Patterning Process of CS-7500 <Pattern process recipe by Mark-7> 1. PI Coating (Mark 7) C/S Coater recipe(manual) STEP Time Speed Acceleration Dispense Arm Arm HMDS (HP) 60 X 20 s (sec) (rpm) (rpm/sec) 1 2 1 10.0 50 1000 1 Home Home COL 23 X 60 s 2 5.0 0 1000 0 Home Home 3 10.0 700 2000 0 Home Home COAT 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 4.Exposure2 PLA Broadband alighner Exposure0.1~5J/cm2(at iline) 5.Cure Cure machine:mark-7(tel) Cure steps: r.t. 280 5 min r.t. Atmosphere:N2 2.Exposure1 I-line stepper(gca 8000 DSW WAFER STEPPER) ET 300 msec (150mJ/cm2) focus 0.5μm Development recipe STEP Time Speed Acceleration Dispense 3.Development (Mark 7)/Bake (sec) (rpm) (rpm/sec) C/S 1 1.0 1000 10000 0 2 3.0 1000 10000 1 7 DEV 3 1.0 500 10000 1 7 4 1.0 100 10000 1 7 C/S 5 4.0 30 10000 1 7 6 36.0 0 10000 5 7 5.0 0 10000 5 8 5.0 500 10000 3 4 9 9 5.0 2000 10000 3 4 9 10 20.0 3000 10000 0 Development(TMAH 2.38%)Rate:0.6 L/min Rinse(DI water)rate:1.2 L/min Back rinse(di water)rate:150 ml/min Cup exhaust:60 Pa Nozzle:Stream nozzle Dispense7:Developer dispense 13 13
Spin curve of CS-7500 (example) Thickness after Prebaking(μm) 1.9 1.7 1.5 1.3 1.1 0.9 0.7 0.5 500 1500 2500 3500 4500 5500 Rotation speed(x rpm 120sec) 14 14