Advances in Optical Polishing...CV Nanotechnology Inc. CMP User Group Meeting May 16, 2012. Improve...
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Advances in Optical Polishing Floyd McClung [email protected] CV Nanotechnology Inc. CMP User Group Meeting May 16, 2012
Transcript of Advances in Optical Polishing...CV Nanotechnology Inc. CMP User Group Meeting May 16, 2012. Improve...
Advances in Optical Polishing
Floyd [email protected] Nanotechnology Inc.
CMP User Group MeetingMay 16, 2012
Improve Optical Materials Performance
UV - Fused Silica, Fluorides (CaF2, MgF2, BaF2), Sapphire
IR - ZnSe, ZnS, Ge, Si, AlON, Spinel, GaAs, Sapphire
Visible - Many glass types (e.g. BK7), Sapphire
Goal – decrease scratches and surface flaws that can be absorption and/orscatter points for light. Too much absorption can actually alter asubstrate’s chemical properties, rendering it useless and scattering canresult in energy loss within the optical system, reducing the efficiency.
Optical Polishing Processhttp://www.youtube.com/watch?v=caIE2YX-Peg
Optical Polishing Processhttp://www.youtube.com/watch?v=9eI0jnfrbu0
New Polishing Equipment
MRF® Technology CNC Polishing
Advances in Particle Processing
• Particle Processing
– Typical polishing abrasives• ceria, alumina, silica, zirconia, diamond
– Modify particle size, shape, phase, morphology
Fused Calcined Precipitated
Alumina particles by different processes
Alumina Particle Modification
Boehmite
Gamma
Theta
Delta
Alpha
0.1 mm
0.3 mm
0.5 mm
0.8 mm
1.0 mm
0.001 mm
0.005 mm
0.01 mm
0.1 mm
0.5 mm
cubic
vermicular
oval
spherical
CrystalPhase
ParticleShape
UltimateParticle
SizeAgglomerate
Size
Surface charge and surface coating can be modified
Advances in Particle Processing
– Additional improvements in processing, filtering, etc.
d50 = 0.8 mm d50 = 0.4 mm
d50 = 0.2 mm
Advances in Slurry Chemistry
Improved slurry chemistry modifies the substrate surface and/orparticle to enhance removal rate, surface finish, cleanability, etc.
0
0.5
1
1.5
2
2.5
SapphireBK7
ZnSe
Normalized Removal Rate
Optical Material
No additive
Formula A
Formula B
Formula C
Improve Surface Finish
Goal < 0.1 nm RA surface finish
Conclusions
• Similar to semicon CMP, advanced abrasives andchemistry can enable better performing optics
– In addition, process time can be improved with advancedslurries
– However, most optical fabrication facilities are notequipped to handle hazardous materials or multiplecomponent slurries
– Additional work continues on low or zero rare earthcontaining slurries
