Whitepaper v1.0 October 2012 Towards fabless photonic integration by Pascual Muñoz, CEO of VLC Photonics Page 1/3 www.vlcphotonics.com Brief historical perspective Photonic integraon allows to combine mulple opcal funconalies into a single monolithic chip. Making this process generic allows a vercal specialisaon through the value chain, by involving several spesialised partners at different stages of an opcal system development. This compares to the tradional vercal aggregaon model from a single device manufacturer. Such evoluon mimics the case for the US semiconductor industry [1], where large corporaons as AT&T and IBM, inially designed and produced their own components, and developed the fabs and processes required to manufacture them in house. In me, specialisaon in two parts of the food chain: design and fabricaon, lead to the appearance of fabless design houses and pure-play foundries. Considering photonics, the seed for generic integraon appeared in Europe by 2007 [2], although some early work by HHI in 2000 already contains the spirit of generic photonic circuits [3]. Current state of the art An overview example of relevant photonic foundries offering generic integraon manufacturing services has been summarised in Table I. Operaonally, these foundries can be described as follows: some foundries are publicly funded research instuons (like IMEC [4], CEA-LETI [4], IME [5], HHI [6], TU/e COBRA [6] or IMB-CNM [7]), whereas other are privately held companies (AMO [8], Luxtera [9], Oclaro [6], or LioniX [10]). Most of them are located in Europe, although USA and Asia are quickly catching up. A significant difference exists on the current state of access to these foundries. Silicon is well seled and public access is already available, while access to generic Indium Phosphide (InP) technology is sll being developed through brokered research projects, with a roadmap for making it more openly available [11]. While some foundries only perform dedicated fabricaon runs, in most cases, they offer Mul-Project Wafer (MPW) runs, sharing the wafer space amongst different designers by dividing it into recules. Formalisaon of such access into a MWP run is done either directly with the foundry or through a brokering organisaon as ePIXfab, JePPIX or OpSIS. The track record on MPW runs is currently hold by IMEC/CEA-LETI through ePIXfab, counng at the end of 2012 with nearly 30 runs in Silicon-on-Insulator (SOI) since 2007. On the InP side, TU/e COBRA has issued one MPW run per year since 2007, hence at the fall of 2012 a total of seven will have been completed. LioniX finished its first TripleX MPW on Si3N4 in 2012, and is already planning the second one. The current photonic integraon technologies can be considered stable, mature and well developed in terms of opcal performance. Table I also shows the available photonic building blocks within each plaorm. For SOI, the trend during 2011 was the inclusion of ring modulators and photodetectors. This is currently being offered, or planned to be in the very short term, by all SOI plaorms. The combinaon with CMOS electronics is a feature offered exclusively up to now through OpSIS using Luxtera’s technology. For InP, the adaptaon of Oclaro's industrial fab (tradionally a component manufacturer using a vercal integraon model) to produce generic PICs was certainly a milestone, whereas HHI is the sole generic InP foundry offering a high speed (balanced) photo-detector that can be combined with other passives. Silicon Nitride technology is mature but sll relavely unexplored, owing to its very recent jump into the generic foundry arena. For interfacing with external designers, foundries usually offer tools like the Photonic Design Kits (PDK), usually available in most of the plaorms. PDK's allow to perform in a seamlessly integrated soſtware environment both the photonic simulaon and the mask layout, incorporang specific process informaon from each foundry. Whereas PhoeniX Soſtware [12] is becoming the de facto standard in Europe, some foundries have proprietary libraries embedded into EDA soſtware as Cadence. The foundries not
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Whitepaper v1.0October 2012
Towards fabless photonic integrationby Pascual Muñoz, CEO of VLC Photonics
Page 1/3www.vlcphotonics.com
Brief historical perspective
Photonic integration allows to combine multiple optical functionalities into a single monolithic chip. Making this process generic allows a vertical specialisation through the value chain, by involving several spesialised partners at different stages of an optical system development. This compares to the traditional vertical aggregation model from a single device manufacturer. Such evolution mimics the case for the US semiconductor industry [1], where large corporations as AT&T and IBM, initially designed and produced their own components, and developed the fabs and processes required to manufacture them in house. In time, specialisation in two parts of the food chain: design and fabrication, lead to the appearance of fabless design houses and pure-play foundries. Considering photonics, the seed for generic integration appeared in Europe by 2007 [2], although some early work by HHI in 2000 already contains the spirit of generic photonic circuits [3].
Current state of the art
An overview example of relevant photonic foundries offering generic integration manufacturing services has been summarised in Table I. Operationally, these foundries can be described as follows: some foundries are publicly funded research institutions (like IMEC [4], CEA-LETI [4], IME [5], HHI [6], TU/e COBRA [6] or IMB-CNM [7]), whereas other are privately held companies (AMO [8], Luxtera [9], Oclaro [6], or LioniX [10]). Most of them are located in Europe, although USA and Asia are quickly catching up. A significant difference exists on the current state of access to these foundries. Silicon is well settled and public access is already available, while access to generic Indium Phosphide (InP) technology is still being developed through brokered research projects, with a roadmap for making it more openly available [11]. While some foundries only perform dedicated fabrication runs, in most cases, they offer Multi-Project Wafer (MPW) runs, sharing the wafer space
amongst different designers by dividing it into reticules. Formalisation of such access into a MWP run is done either directly with the foundry or through a brokering organisation as ePIXfab, JePPIX or OpSIS. The track record on MPW runs is currently hold by IMEC/CEA-LETI through ePIXfab, counting at the end of 2012 with nearly 30 runs in Silicon-on-Insulator (SOI) since 2007. On the InP side, TU/e COBRA has issued one MPW run per year since 2007, hence at the fall of 2012 a total of seven will have been completed. LioniX finished its first TripleX MPW on Si3N4 in 2012, and is already planning the second one.
The current photonic integration technologies can be considered stable, mature and well developed in terms of optical performance. Table I also shows the available photonic building blocks within each platform. For SOI, the trend during 2011 was the inclusion of ring modulators and photodetectors. This is currently being offered, or planned to be in the very short term, by all SOI platforms. The combination with CMOS electronics is a feature offered exclusively up to now through OpSIS using Luxtera’s technology. For InP, the adaptation of Oclaro's industrial fab (traditionally a component manufacturer using a vertical integration model) to produce generic PICs was certainly a milestone, whereas HHI is the sole generic InP foundry offering a high speed (balanced) photo-detector that can be combined with other passives. Silicon Nitride technology is mature but still relatively unexplored, owing to its very recent jump into the generic foundry arena.
For interfacing with external designers, foundries usually offer tools like the Photonic Design Kits (PDK), usually available in most of the platforms. PDK's allow to perform in a seamlessly integrated software environment both the photonic simulation and the mask layout, incorporating specific process information from each foundry. Whereas PhoeniX Software [12] is becoming the de facto standard in Europe, some foundries have proprietary libraries embedded into EDA software as Cadence. The foundries not
Page 2/3www.vlcphotonics.com
having PDK's limit designers to communicate only at a basic GDS level. Back-end processes, as packaging, are an important open issue already identified and being addressed by most of the foundry players. The development of generic packages that can be reused amongst different PIC designs, minimising non-recursive engineering costs, is already in place for InP through Oclaro and HHI, whereas it will be developed for SOI by IMEC in the midterm.
As an example of these generic integration platforms, Figure 1 shows some optical chips developed in the past at several foundries and MPW runs by members of VLC Photonics, a design-house spinning-off from the Technical University of Valencia (Spain): (a) shows a frecuency discriminator receiver manufactured in InP, (b) shows an OCDMA decoder in Si3N4 (TripleX), (c) represents some microwave phase-shifters in InP, and (d) pictures a narrow-band photonic beam-former chip in SOI.
Area Area Project Project Area Area Area Area Area Project
BUILDING BLOCKS
Generic buldingblock availableTable I. Photonic foundry examples
Fig. 1. Examples of manufactured Photonic Integrated Circuits using four different generic platforms.
(b) (c)
(d)
(a)
Page 3/3www.vlcphotonics.com
What's next?
Europe was certainly the cradle of generic photonic integration, both for Silicon and InP photonics, but as of 2011, US is quickly catching up with initiatives like OpSIS for SOI. While most of the electronic semiconductor industry already offshored its production to Asia [13], it is still unclear whether the EU and US photonic industry will do it as well in the near future. As an example, OpSIS first MPW run was already transferred to IME in Singapore.
According to current roadmaps, EU InP generic foundries will be established commercially as soon as 2016 [11]. Currently there is no known initiative to establish an InP generic foundry in the US, although we might see a step forward in the short term by some InP US fabs, as it happened for Silicon.
The fabless photonic design and prototyping ecosystem, fostered by these generic integration platforms, started to develop in Europe by 2009. Nowadays, it is made up of half a dozen SMEs, this number might keep growing in the short term. Conversely, in the US, start-ups have a strong linkage to a foundry/technology, but fabless PIC companies based upon generic integration might soon appear if developments go on.
References
[1] J.T. Macher and D.C. Mowery, "Vertical specialization and industry structure in high technology industries," Advances in Strategic Management, vol. 21, pp. 317–355, 2004.[2] "Towards a foundry model in micro- and nanophotonics: A vision for Europe," Tech. rep., EC FP6 NoE ePIXnet Steering Committee, March 2007.[3] M. Hamacher et Al., "Monolithic integration of lasers, photodiodes, waveguides and spot size converters on GaInAsP/InP for photonic IC applications," in Indium Phosphide and Related Materials, Proc. of the IEEE International Conference on, pp. 21–24, 2000.[4] "ePIXfab, the Silicon photonics platform." http://www.epixfab.eu.[5] "Institute of Microelectronics, Singapore." http://www.ime.a-star.edu.sg.[6] "Joint European Platform for InP-based Photonic Integrated Components and Circuits (JePPIX)." http://www.jeppix.eu.[7] "Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica (IMB-CNM)." http://www.imb-cnm.csic.es.[8] "Gesellschaft für Angewandte Mikro- und Optoelektronik." http://www.amo.de.[9] "Optoelectronic System Integration in Silicon.” http://depts.washington.edu/uwopsis/.[10] "LioniX, microfluidics and integrated optics." http://www.lionixbv.nl.[11] M. Smit, M. Wale, D. Robbins, and H. Ambrosius, "The road to a multi-billion Euro market in InP-based Integrated Photonics: JePPIX ROADMAP 2012," Tech. rep., JePPIX, 2012.[12] “Phoenix Software” http://www.phoenixbv.com.[13] C. Brown, G. Linden, and J.T. Macher, "Offshoring in the Semiconductor Industry: A Historical Perspective," Brookings Trade
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