Facilities
The
Centre
The Technology
Epitaxy
Key Capabilities
III-V Fabrication
Planar Silica
Coatings
Packaging
Reliability Testing
Systems Experiments & Measurements
The
Centre
CIP is located at Adastral Park, Martlesham Heath near Ipswich. The park has been developed as a Science Park attracting companies such as BT, Cisco, Alcatel and Fujitsu. The academic institutions are represented by Essex University, UCL and the Cambridge/Massachusetts Institute of Technology (CMI). The park has all the amenities required to support a top class workforce and the infrastructure to support networking and collaboration between co-located businesses.
The CIP building has a prestigious facility on two floors totaling 3,700m².
The ground floor consists of:-
309m² Class 10,000 clean room
52m² Class 1,000 clean room
108m² Semi clean area
640m² fully serviced Laboratories
These labs all contain anti-vibration bases and air conditioning to facilitate equipment operating to fine tolerances, Chemical workstations, N², DI Water and special gases as required.
The ground floor also accommodates two high-class conference rooms and a video conferencing suite.
The first floor consists of measurement laboratories and workstations for up to 100 people mixed between open plan areas and enclosed offices.
Centralised extract systems, building management, DI Water plant and Bulk Nitrogen enable low cost, high quality and safe environments throughout the building.
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The
Technology
The strength of CIP lies in its hybrid integration technology, linked closely with its expertise on III-V optoelectronic and planar silica waveguide technologies.
Hybrid integration is the integration of materially different components onto a single platform. Different functional elements (optical, electrical, biological, etc) are brought together into a combined unit or sub-system to enable a specific application that would not otherwise be easily achieved.The functional element can be a discrete device or as technologies develop could be a monolithic chip, photonic nanostructure or a magneto-optic element for example.
In photonic integration, as in electronic integration, there is a balance between monolithic and hybrid integration. Monolithic integration provides simplicity in handling and packaging, but the yield of monolithic components reduces as complexity increases. The balance is not fixed, but will change with time. As device processes become more robust, and yields increase, there will be a higher level of monolithic integration which will be enabled through the continued development of the epitaxial regrowth processes. These allow separately optimised devices to be monolithically integrated with high yield.
CIP have developed planarising regrowth techniques for MOVPE growth and demonstrated these on EAMs, SOAs and lasers. In order to be successful in hybrid integration, a holistic design and fabrication approach is required throughout. The active components, silicon optical bench and planar silica waveguides are specifically designed and optimised for integration.This requires additional fabrication stages and design to incorporate the features required to facilitate the assembly and packaging process. This is a process that only works well when all of the capabilities are coupled closely together.
The following sections describe in detail the capabilities within the facility.
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Epitaxy
CIP has a comprehensive in-house III-V growth capability underpinning the work on active devices. This is strongly integrated with the centre’s device design, fabrication and test facilities giving a tight feedback loop facilitating rapid development of solutions.
The success of integration-enabling technologies such as selective area overgrowth is critically dependent on tight linkage between growth and fabrication. Our centre specialises in InP / InGaAsP/ InAlGaAs materials growth, but our unique added value is in the selective area growth and overgrowth for fabrication of three dimensional structures and optoelectronic integration.
The centre has four MOVPE systems, including one Aixtron 2400G3 with multi (8x2”) wafer capacity and three horizontal reactor systems with 1x2” wafer capacity.
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Key
capabilities:
Very high quality multi quantum well structures in InP / InGaAsP / InAlGaAs with accurate control of compositions to engineer complex well profiles .
Highly uniform growth over multiple 2” wafers with excellent repeatability .
Toolkit for engineering complex three dimensional structures using low pressure, atmospheric pressure and halide assisted MOVPE:
Selective area growth using dielectric masks for local tailoring of morphology and composition.
Overgrowth to form high reliability buried heterostructures, including semi-insulating current blocking structures for low capacitance devices, high efficiency current blocking structures for forward biased devices and optimised low resistance contact structures.
Overgrowth of nanometre scale gratings without deformation.
High efficiency (< 0.1db per interface) butt joining of active and passive devices for horizontal integration.
In-situ etching of structures in the MOVPE reactor prior to overgrowth
The growth capability is supported by a comprehensive range of analysis facilities:
High resolution double crystal x-ray diffraction with automatic wafer mapping and modelling.
Room temperature photoluminescence with fully automated rapid wafer mapping.
High resolution spectrophotometer for band edge measurement.
Electrochemical carrier concentration profiling.
Hall mobility and carrier concentration measurement.
Nanometre resolution scanning electron microscope (also CamScan).
High resolution surface profilometers.
Imaging interferometer for surface profiling.
Extensive in-house knowledge of a range of analysis techniques including secondary ion mass spectrometry, low temperature photoluminescence and transmission electron microscopy allowing effective intelligent interaction with groups providing such services.
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III-V Fabrication
The III-V fabrication facility operates with manual processing of small batch sizes, typically 4 units per batch. The units can be full 2” wafers or smaller fragments (quarter wafers or 10mm x 15mm fragments are commonly used).
A typical six mask level process for a buried heterostructure laser type device would have a cycle time of three to five weeks per batch.
Resist coating and developing are performed manually, and photolithography uses contact or proximity printing from 1X chrome on quartz photomasks.
Spray coating for patterning of large feature topography.
SSI Rapid Thermal Annealer.
Two manual Karl Zeiss aligners
Canon contact/proximity aligner
EVG620 semi-automated aligner –with robot wafer handling for wafers from 3” to 6” diameter - enabled for near field holography
E-beam lithography is performed with an EBMF10.5 raster scan tool, 70nm resolution is routinely achieved on structures such as gratings and photonic band gap devices.
Joel E-beam 5FEL 10-15nm resolution machine in commissioning phase
Selective and non-selective wet etches are used inside laminar flow chemical workstations.
Dry etch facilities include
ICP etch system for deep silicon and deep iiiv
oxygen plasma
oxygen RIE
methane/hydrogen RIE (for III-V semiconductor)
SF6 and Freon based RIE (for dielectric etching)
argon sputter etching.
Platinum sputter etching
Silicon nitride and silica dielectric layers are deposited by plasma enhanced chemical vapour deposition (PECVD), silica can also be deposited using atmospheric pressure chemical vapour deposition.
Metallization with Titanium, Platinum and Gold is performed in a loadlocked RF sputtering system. There is also an electron-beam evaporator, and a small thermal filament evaporator used for lift-off metal processes.
Gold plating is available from a sulphite based DC plating bath.
Wafers are thinned using lapping and chemomechanical polishing on Logitech machines.
Dicing is performed with Karl Zeiss scribe and break tools, or with a high precision wafer saw (sawing is used primarily for silicon wafers).
Devices can be assessed on wafer using an autoprober linked with a parameter analyzer test setup.
Analysis equipment available in the fabrication facility includes Hitachi field emission Scanning Electron Microscope equipped with cathodoluminescence, electron beam induced current (EBIC), and X-ray investigation capabilities.
Dektak surface profilers
Canon laser flatness tester
Nanospec film thickness analyzer
Leitz scanning slit linewidth measurement
Wyko interferometer
DME atomic force microscope
A liquid chromatography system is used to make regular checks on the quality of the ultrapure water delivered to the cleanroom, airborne particulate levels are checked with a laser based particle counter.
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Planar
Silica
A four tube thermal oxidation furnace is used to produce thick thermal oxide layers on silicon, and is also available for dopant diffusion into silicon.
Doped silica waveguide materials and silica cladding layers are deposited in two multi-wafer Flame Hydrolysis Deposition (FHD) systems with 4" and 6” wafer capability. These are fed from a bubbler system to dope with boron, phosphorus and germanium. Rare earth doping is performed using a solution doping capability. A vertical sintering furnace with silicon carbide furnace furniture is used to fuse the porous doped silica layers deposited in the FHD process.
Oxide etching is performed with an Oxford RIE80 plasma etching machine.
In addition we have:-
Metrology tools for index and thickness measurement
BeamProp, FIMMWAVE, FIMMPROP modelling software
Characterisation facilities
Packaging facilities for array type devices
The lithography and metallization tools are described in the III-V Fabrication section
Planar Silica wafer fabrication, and the fabrication of silicon optical bench elements is performed in the main cleanroom alongside the III-V fabrication, sharing equipment for PECVD, metallization and lithography. Wet etching for V-grooves, pedestals and vertical alignment structures for 4” silicon wafers uses KOH or EDP as appropriate for the particular structure. SU-8 is patterned to create alignment structures. Gold/Tin solder is deposited by evaporation. High precision (sub-micron) wafer dicing and milling capability is used to machine structures into the silicon.
Key skills exist in the design of high speed interconnects and transmission line structures, and considerable “Design for integration” expertise has been developed.
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Coatings
A Leybold APS 1104 DWDM ion-assisted electron-beam evaporator is used to create high performance DWDM filters with 100GHz and 50 GHz passbands.
The existing Balzers optical coating plant was completely refurbished and a custom made control and monitoring system installed. Novel optical monitoring methods have been developed for improved control.
The analysis area has been enhanced by the purchase of an Aquila NKD 6000 instrument for the measurement of refractive index and thickness of optical films and surfaces. This instrument has proved extremely useful for other work areas of the centre. An automated surface cleaning system is used to prepare samples for coating.
A full suite of commercial and bespoke software is available including FilmStar, Macleod, Multilayer.
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Packaging
Extensive facility for prototype packaging of optoelectronic devices, including:
- K&S wire bonders & die bonders
- Finetech Flip chip bonder for precision flip chip bonding
- Co-axial laser welding system
- Fibre sub-assembly facility
- Hybrid integration device assembly
- 40GHz packaging capability
- Array packaging
- Free-space optical packaging
- Bespoke package design
- Silicon Optical Bench assembly
The centre also has a workshop equipped with CNC tools, which enables the machining of complex or “one-off” packages. There is a precision machining facility for submicron accuracy machining, dicing and polishing of silicon and silica materials.
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Reliability Testing
CIP has a capability for overstress testing of optoelectronic devices in ovens or on hotblocks. Lifetesting at temperatures up to 175C is possible, and the ovens have sophisticated mounts for holding and monitoring double ended devices such as SOAs during lifetest.
There is capacity for testing up to about 500 devices concurrently. As well as measurement equipment for re-characterisation, detailed physical examination can be performed using SEM, EBIC and EDAX analysis.
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Systems
Experiments & Measurements
CIP has a comprehensive and world leading capability in measurements and optical systems testing. These facilities include:
Signatone electrical wafer probe station
Bespoke manual electrical bar probe station
Bespoke automated bar test station for electrical and LI characterisation (far field with IR - CCD)
Bespoke modulator mode analysis and loss characterisation
Bespoke laser and SOA chip far field and LIV characterisation
Bespoke passive component optical amplitude and delay response characterisation
Laser 2000 PMD/PDG measurement
Agilent 8510C 50 GHz Network analyser with RF wafer probes
Agilent 8603 50 GHz Lightwave component analyser
Range of 20 GHz RF spectrum analysers with preselected mixers up to 110 GHz
Agilent 8565EC 50 GHz RF spectrum analyser
Proprietary rapid alpha parameter characterisation
Bespoke optical amplifier characterization
Luna precision reflectometer.
Short pulse characterisation (to 100 fs)
Bit error rate (BER) measuring (2off @ 40Gb/s, 3off @ 20Gb/s and 10Gb/s, 8off @ 2.5Gb/s)
Multiple wavelength optical sources and modulators (40Gb/s and 10Gb/s)
High-speed and short pulse optical sources (>80Gb/s), optical sampling (>100Gb/s), High speed optical detectors, clock recovery and OTDM demultiplexing.
Optical transmission measurements (50GHz), high speed oscilloscopes andRF spectrum analysers (50GHz), real time oscilloscopes (2.5GHz)
Optical diagnostics - optical spectrum analysers, optical pulse correlators, coherence analysers, power meters and RF electronics
Large quantity of optical component hardware including optical filters, couplers, switches, polarisation controllers, delay lines, erbium doped fibre amplifiers, attenuators, AWGs, isolators.
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