7 photonic integration-part 2 bonding
DESCRIPTION
Photonic integrationTRANSCRIPT
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Wafer bonding for integrated optics
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Physics of wafer bonding
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Glass frit bondingGlass frit a slurry of fine glass particles in an appropriate carrierliquid Full sheet deposition or applied by screen printing Slurry heated to melt the glass particles Bonding upon solidification
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Anodic bonding
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Metallic bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Molecular wafer bonding
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Surface cleaning
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Surface cleaning
How to get rid of these particles?
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Surface cleaning
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Molecular wafer bonding
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Surface activation
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Surface activation
Deposited SiO2 allows to bond anything to anything
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Surface activation
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Molecular wafer bonding
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Room temperature attachment
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Molecular wafer bonding
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Annealing
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Annealing
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive wafer bonding
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Adhesive bonding
Why adhesive die to wafer bonding? Less stringent requirements on surface quality
Micro-roughness Particle contamination Other types of contamination
Low temperature bonding process Planarization of SOI topography by spin coating
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DVS-BCB adhesive bonding
Why DVS-BCB as a bonding agent? Low temperature bonding process (Tbond=250C) Very good planarization properties High glass transition temperature (Tg> 350C) High resistance against chemicals Known material in IC industry (packaging)
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DVS-BCB adhesive bondingChemical formula
Commercially formulated by DOW as a B-staged oligomersolution (35% pre-polymerized)
By spin-coating: layer thicknesses of 1m to 25m available For our application: much thinner bonding layers are required
Dilution of the commercially available DVS-BCB using mesitylene
Stable spin coating of layer thicknesses down to 30nm
Si
CH3
CH3
Si
CH3
CH3
O
1,3-divinyl-1,1,3,3-tetramethyldisiloxane-bisbenzocyclobutene
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DVS-BCB adhesive bondingOverview of the bonding process
Si-substrate
SiO2Si
BCB BCB BCB
BCB coatingWafer cleaning
Solvent evap + prepolymerization
Die attachment
BCB
BCB curing (pressurized)
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DVS-BCB adhesive bondingCleaning of the SOI wafer surface using Piranha clean Standard Clean - 1 solution Standard Clean 2 solution
Particle free hydrophilic surface
Cleaning of the InP/InGaAsP die surface by Sacrifical removal of an InP epitaxial layer using 3HCl:H2O Sacrificial removal of an InGaAs layer using H3PO4:3H2O2:H2O
Particle free hydrophilic surface
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DVS-BCB adhesive bondingPlanarization properties
Double spin coating has higher DOP than single coating with the same aggregate thicknessCuring profile and density of topography important for DOP
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DVS-BCB adhesive bondingDie attachment process
Aligned attachment of dies and structured SOI wafer to carrier wafers
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DVS-BCB adhesive bondingDie attachment process
Mounting of the carrier wafers in bonding chamber (carrier wafers are mechanically aligned)
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DVS-BCB adhesive bondingDie attachment process
Evacuation of bonding chamber and attachment of dies (150C)
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DVS-BCB adhesive bondingDie attachment process
Purging of the bonding chamber evaporation or release of temporary adhesive
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DVS-BCB adhesive bonding
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Equipment
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Bonding equipment
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Bonding equipment
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Characterization equipment
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Characterization Equipment
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Characterization Equipment
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Substrate removal
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Bonding equipment
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Unprocessed opto-electronic layer structure
Processed SOI waveguide wafer
Die to wafer bonding Substrate removal
Processing (definition of the component)
CMOS wafer
Photonic layer
Bonding of InP/InGaAsP dies and device processing
Bonding unprocessed dies using pick and place lowers needed alignment accuracy increases throughput
After die to wafer bonding all processing steps are wafer scale processes
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Fabrication of bonded devices Photodetectors
Surface illuminated photodetector
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Fabrication of bonded devicesPhotodetectors
Evanescently coupled MSM photodetectors
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Fabrication of bonded devicesPhotodetectors and laser diodes
Inverted adiabatic taper approach Processing of both laser diodes and photodetectors identical
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InP Microdisk Laser on Silicon
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Multi-wavelength Laser on Si
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III-V Photodetectors on Silicon
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III-V Photodetectors on Silicon
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Nonlinear ring resonators
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Conclusions
Wafer bonding and die-to-wafer bondingtechnology is a very versatile technology with awide range of applicationsMolecular and adhesive (die-to-) wafer bondingare enabling technologies to realize complexphotonic integrated circuitsFuture research: to scale up the integration density todemonstrate the feasibility of complexactive/passive photonic integrated circuits