Prototype Showcase What is a metamaterial How our 2D sample was created How our phase mask was created SEM images of 2D sample and phase mask Metamaterials A periodic material that has photonic or phononic properties ID: 414527
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Slide1
MetamaterialsSlide2
Prototype Showcase
What is a metamaterial?
How our 2-D sample was created
How our phase mask was created
SEM images of 2-D sample and phase maskSlide3
Metamaterials
A periodic material that has photonic or phononic properties.
*Taken From 3.042 handout & Physics Worlds 2005 “Sound Ideas”Slide4
Deliverables
3-D periodic structure with micro-scale periodicity
Macro-scale representations of the structuresSlide5
Prototype Design
2-D structure
phase mask
3-D structure
2-D structure:
2 microns thick,5 microns thick,
15 microns thick
Variable spacing
3-D structure:
Very thick (~50 microns)
Variable spacingSlide6
Contact Lithography
Coat
Exposure
Develop
plain Si wafer
coat with HMDS to make Si wafer hydrophobic
coat with SU-8 2015 photoresist using spin coater
soft bake @95° to evaporate solvent and cut into pieces
UV exposure for either 15, 20, 25, or 30 seconds
flip 90° and expose again
post bake at first 65° then 95° to promote crosslink formation
submerge in PM acetate to dissolve unexposed photoresist (20 min
）
submerge in isopropanol to wash away all remnants—final structureSlide7
Phase mask
Step 1
Step 2
Step 3
Vacuum sample with open bottle of fluorosilane so that it evaporates onto sample.
Layer with PDMS and heat at 65°to 75°for at least three hours.
Gently peel off PDMS
layer as phase mask.Slide8
Fabrication and Processing
SU-8 2002:
15 seconds,
20 seconds,
25 seconds
SU-8 2005:
25 seconds,
30 seconds,
35 seconds,
40 seconds
SU-8 2015:
15 seconds,
20 seconds,
25 seconds,
30 seconds,
35 seconds,
40 seconds,
45 seconds
Type of PhotoresistSlide9
Prototype Functionality
Thick Film Photoresist
Sin (70) = 58 / t
Calculation:
Thickness (t) ~ 61 microns
Success!Slide10
Prototype Functionality
2-D Patterns
Top-down view:
Hole Spacing ~
3.38 um
Hole Length ~
1.56 um
Hole Height ~
1.54 um
Cross-section view:
Width of top ~
1.81 um
Width of bottom ~
1.00 um
Height ~
10.00 umSlide11
Prototype Functionality
Problems in 2-D patterns
Over exposure
Un-washed monomer
Non-uniform columns
Width of top ~
1.81 um
Width of bottom ~
1.00 umSlide12
Prototype Functionality
Phase maskSlide13
?
2-D Pattern
Phase Mask
3-D Pattern
CAD Model
3-D Printing Model
Actual SampleSlide14Slide15
Questions?