As a result of significant investments in the development of foundry technology infrastructure (well over €50 M in European and national projects so far) Europe is making substantial progress in this new way of working. In this chapter, we'll give an overview of the present status of the foundry capabilities of the JePPIX partners and a prediction for the status in 2018 and 2020.
In 2007 the COBRA institute at TU Eindhoven started pioneering small scale foundry access to a first generation research platform under the framework of the EU-FP6 Network of Excellence ePIXnet They used their own cleanroom facilities and know-how. Process capabilities have been gradually improved and presently support design of ASPICs integrating lasers, optical amplifiers, modulators and detectors with 10 Gbits/s speed, and a variety of passive optical components.
In 2009 the FP7 EuroPIC project began with the mission of transferring the foundry model from a university environment into industrial platforms (the wafer fabs of Oclaro in the UK and Fraunhofer HHI in Germany) They also started development of process design kits (PDK) and standardized packaging solutions.
EuroPIC successfully pioneered the world’s first photonic MPW runs in generic industrial foundry processes in 2012. Oclaro tested a transmitter type platform offering a variety of lasers and optical amplifiers, modulators and detectors for 10 Gbits/s operation and passive building blocks like MMIcouplers and AWGs. Fraunhofer HHI tested a receiver type platform offering detectors for operation up to 40 Gbits/s, integrated with a variety of passive devices and thermooptic phase modulators. The COBRA process was licensed to the spin-off company SMART Photonics, providing the first Pureplay foundry services for ASPICs.
LioniX started developing its TriPleXtechnologyfor low-loss dielectric waveguide devices and circuits in 2004. First devices focused on microwave photonics applications, but over the last ten years the technology has been developed into a very advanced platform appropriate for a broad range of applications covering a wide wavelength range - from the visible to the infrared. LioniX has recently become LionIX International after scaling up its activ
Three of the JePPIX foundries continue to offer semi-commercial access to early versions of their foundry processes. The capabilities of the platforms are briefly summarized below. In mid-2016 Oclaro decided to terminate its MPW foundry service for photonic integrated circuits so as to concentrate its resources on its communications products, which has proved to be their core business. Oclaro honours existing commitments but will not be pursuing new business in this area.
1. The HHI platform, starting as a ”receiver only” platform, offers very high speed photodetectors, spot size convertors, thermooptic phase modulators and a variety of passive waveguide components. The RF detectors exhibit an internal responsivity of 0.9 A/W, a dark current <10 nA and an electro-optical bandwidth of 40 GHz. Spot size convertors provide 1.5 dB coupling loss to a cleaved standard single mode fibre. Waveguide propagation loss varies between <1 dB/cm for low-contrast waveguides to some 2 dB/cm for high-contrast waveguides. Multimode interference (MMI) couplers and arrayed waveguide grating (AWG) de/multiplexers have typical losses of 0.5-1 dB and 2-3 dB, respectively.
2. The SMART Photonics platform offers optical amplifiers, RF modulators, detectors and a variety of passive components. The SOAs provide about 50/cm gain and 20mW output power. The RF modulators support 10 Gbits/s modulation with 5 V drive voltage for 2 mm long phase modulators. Detectors have 0.8 A/W responsivity and >20 GHz bandwidth. Waveguide propagation losses are 2-3 dB/cm.
3. LionIX International - The TriPleX platform offers low-loss straight waveguides, bends, S-bends, offsets, splitters, spot size converters, lateral tapers and thermo-optic phase shifters. Combinations of these building blocks allow, for example, the creation of microwave photonics ASPICs through combinations of Mach-Zehnders and micro ring resonators. The current platform has guaranteed losses below 0.5 dB/cm and results reported by customers have been as low as 0.1 dB/cm.
The following extensions and improvements for the platforms are foreseen. All platforms are offering a basic level of platform qualification, including some early yield figures. In addition to the process development activities, work will commence to improve the contents of the PDKs.
- The HHI platform will add transmitter capabilities to its current receiver platform: SOAs, DFB/DBR lasers and EAMs are now available. Further, it will add Polarisation Converters, thus providing the platform with polarisation handling capabilities. The platform will support 25 Gbits/s modulation, either by direct modulation of the DFB lasers or using Electro Absorption Modulators.
- The SMART Photonics platform will offer less than 1 dB/cm waveguide propagation loss and support 100 nm device features (using 193 nm DUV scanner lithography), which will lead to enhanced performance and reduced insertion loss of passive components. Further, it will add Spot Size Converters and improve the efficiency of its detectors and modulators.
- The TriPleX platform will add more advanced building blocks to its current library. Structures like AWGs and micro ring resonators are on the roadmap of LioniX for implementation in the platform. It is also foreseen that the guaranteed loss will be lowered close to the best-case reported value of 0.1 dB/cm and that low power phase tuning will be introduced.
In 2018 all platforms will offer an extended level of platform qualification, including yield and lifetime figures. All platforms will offer low loss waveguides (<1 dB/cm), efficient SOAs, modulators and detectors, polarization converters and spot-size converters and provide a performance comparable to the state of the-art application specific processes available on the market.
The TriPleX platform will offer integrated MEMS structures that enable, for example, low-cost high- precision coupling between InP and TriPleX PICs, thus providing a hybrid platform that combines the best of InP and TriPleX technology; high performance active devices and very low-loss and highQ passive functionality.
Electronic photonic co-integration is an important current R&D challenge. In 2010, research started on the InP Membrane on Silicon technology (IMOS). This approach will make it possible to fabricate InP photonic ICs on silicon wafers. In 2016 we started research on wafer scale integration of InP photonics and BiCMOS electronics, and first demonstrators are expected in 2018. Small scale experimental access would follow shortly after. The intimate integration of high speed electronics, digital electronics and photonic ICs in the same chip will have a profound impact on module costs and performance.
In addition to high performance photonic technologies, R&D-level MPW runs will be offered that combine wafer-scale photonic electronic co-integration processes. In these processes, the full functionality of photonic platforms will be provided on top of (Bi)CMOS ICs in which the driver, receiver and control electronics are integrated.
The potential of a foundry process is, to a large extent, determined by the maturity of the technology reflected in the contents of the Process Design Kit provided to its users. Such a PDK is compatible with design software and contains in general:
- Technology set-up files, describing the mask layers involved in the fabrication process,
- Pre-defined mask layouts and specifications for a set of Basic Building Blocks,
- Mask layout and accurate models for a variety of more complex components,
- Design and verification rules.