Lockheed Martin looks to pooling and optical I/O
Electronic systems must peer into ever-greater swathes of the electromagnetic spectrum to ensure a battlefield edge.
Michael HoffSuch electronic systems are used in ground, air, and sea vehicles and even in space.
The designs combine sensors and electronic circuitry for tasks such as radar, electronic warfare, communications and targeting.
Existing systems are custom designs undertaking particular tasks. The challenge facing military equipment makers is that enhancing such systems is becoming prohibitively expensive.
One proposed cost-saving approach is to develop generic radio frequency (RF) and sensor technology that can address multiple tasks.
“Now, each sensor will have to satisfy the requirements for all of the backend processing,” says Michael Hoff, senior research engineer at Lockheed Martin Advanced Technology Laboratories.
Such hardware will be more complex but upgrading systems will become simpler and cheaper. The generic sensors can also be assigned on-the-fly to tackle priority tasks as they arise.
“This is a foundational architectural shift that we see having relevance for many applications,” says Hoff.
Generic sensing
The proposed shift in architectural design was discussed in a paper presented at the IEEE International Symposium on Phased Array Systems and Technology event held in October.
Co-authored by Lockheed Martin and Ayar Labs, the paper focuses on generic sensing and the vast amount of data it generates.
Indeed, the data rates are such that optical interconnect is needed. This is where Ayar Labs comes in with its single-die electro-optical I/O chiplet.
Lockheed Martin splits sensing into two categories: RF sensing and electro-optic/ infrared (or EO/IR). Electro-optic sensors are used for such applications as high-definition imaging.
“When we talk about platform concepts, we typically lump EO/IR into one category,” says Hoff. The EO/IR could be implemented using one broadband sensor or with several sensors, each covering specific wavelengths.
A representation of current systems is shown above. Here, custom designs comprising sensors, analogue circuitry, and processing pass data to mission-processing units. The mission equipment includes data fusion systems and displays.
Lockheed Martin proposed architecture uses two generic sensor types – RF and EO/IR – which can be pooled as required (see diagram below).
For example, greater resources may need to be diverted urgently to the radar processing at the expense of communications that can be delayed.
“It’s a more costly individual development, but because it can be shared across different applications and in different teams, cost savings come out ahead,” says Hoff.
An extra networking layer is added to enable the reconfigurability between the sensors and the mission functions and processing systems that use, process, and digest the dat
Optical interconnect
Data traffic generated by modern military platforms continues to rise. One reason is that the frequencies sensed are approaching millimetre-wave. Another is that phased-array systems are using more elements so that more data streams must be be digitised and assessed.
Lockheed Martin cites as an example a military platform comprising 16 phased-array antennas, each with 64 elements.
Each element is sampled with a 14-bit, 100 gigasample-per-second analogue-to-digital converter. The data rate is further doubled since in-phase and quadrature channels are sampled. Each phased array thus generates 179.2 terabits-per-second (Tbps) while the total system data is 2.87 petabits-per-second.
Algorithms at the sensor source can trim the raw data by up to 256x, reducing each antenna’s data stream to 700Gbps, or 11.2Tbps overall.
Optical communications is the only way to transport such vast data flows to the mission processors, says Lockheed Martin.
Multi-chip modules
Any interconnect scheme must not only transfer terabits of data but also be low power and compact.
“The size, weight and power constraints, whether an optical transceiver or processing hardware, get more constrained as you move towards the sensor location,” says Hoff.
The likelihood is that integrated photonics is going to be required as bandwidth demand increases and as the interconnect gets closer to the sensor, he says.
Lockheed Martin proposes using a multi-chip module design that includes the optics, in this case, Ayar Labs’s TeraPhy chiplet.
The TeraPhy combines electrical and silicon photonics circuitry on a single die. Overall, the die has eight transceiver circuits, each supporting eight wavelengths. In turn, each wavelength carries 32 gigabit-per-second (Gbps) of data such that the 54mm2 die transmits 2Tbps in total.
Lockheed Martin has compared its proposed multi-chip module design that includes integrated optics with a discrete solution based on mid-board optics.
The company says integrated optics reduced the power consumed by 5x, from 224W to 45W, while the overall area is reduced a dozen fold, from 3,527 mm2 to 295mm2.
“You’re going to need optical interconnects at many different points,” says Hoff; the exact locations of these multi-chip modules being design-dependent.
Charles Wuischpard, CEO of Ayar Labs, points out that the TeraPhy is built using macro blocks to deliver 2Tbps.
“There are customer opportunities that require far less bandwidth, but what they want is a very tiny chip with very low energy consumption on the input-output [I/O] transport,” says Wuischpard. “There are different areas where the size, weight and power benefits come into play, and it may not all be with our single chiplet solution that we offer.”
Investor
Lockheed Martin became a strategic investor in Ayar Labs in 2019.
“We see this [Ayar Labs’ optical I/O technology] as a foundational technology that we want to be out in front of and want to be first adopters of,” says Hoff.
Rockley Photonics eyes multiple markets
Andrew Rickman, founder and CEO of silicon photonics start-up, Rockley Photonics, discusses the new joint venture with Hengtong Optic-Electric, the benefits of the company’s micron-wide optical waveguides and why the timing is right for silicon photonics.
Andrew Rickman
The joint venture between Rockley Photonics and Chinese firm Hengtong Optic-Electric is the first announced example of Rockley’s business branching out.
The start-up’s focus has been to apply its silicon photonics know-how to data-centre applications. In particular, Rockley has developed an Opto-ASIC package that combines optical transceiver technology with its own switch chip design. Now it is using the transceiver technology for its joint venture.
“It was logical for us to carve out the pieces generated for the Opto-ASIC and additionally commercialise them in a standard transceiver format,” says Andrew Rickman, Rockley’s CEO. “That is what the joint venture is all about.”
Rockley is not stopping there. Rickman describes the start-up as a platform business, building silicon photonics and electronics chipsets for particular applications including markets other than telecom and datacom.
Joint venture
Hengtong and Rockley have set up the $42 million joint venture to make and sell optical transceivers.
Known for its optical fibre cables, Hengtong is also a maker of optical transceivers and owns 75.1 percent of the new joint venture. Rockley gains the remaining 24.9 percent share in return for giving Hengtong its 100-gigabit QSFP transceiver designs. The joint venture also becomes a customer of Rockley’s, buying its silicon photonics and electronics chips to make the QSFP modules.
“Hengtong is one of the world’s largest optical fibre cable manufacturers, is listed on the Shanghai stock market, and sells extensively in China and elsewhere into the data centre market,” says Rickman. “It is a great conduit, a great sales channel into these customers.”
The joint venture will make three 100-gigabit QSFP-based products: a PSM4 and a CWDM4 pluggable module and an active optical cable. Rickman expects the joint venture to make other module designs and points out that Rockley participates in the IEEE standards work for 400 gigabits and is one of the co-founders of the 400-gigabit CWDM8 MSA.
Rockley cites several reasons why the deal with Hengtong makes sense. First, a large part of the bill of materials used for active optical cables is the fibre itself, something which the vertically integrated Hengtong can provide.
China also has a ‘Made in China 2025’ initiative that encourages buying home-made optical modules. Teaming with Hengtong means Rockley can sell to the Chinese telecom operators and internet content players.
In addition, Hengtong is already doing substantial business with all of the global data centres as a cable, patch panel and connector supplier, says Rickman:“So it is an immediate sales channel into these companies without having to break into these businesses as a qualified supplier afresh.”
A huge amount of learning happened and then what Rockley represented was the opportunity to start all over again with a clean sheet of paper but with all that experience
Bigger is Best?
At the recent SPIE Photonics West conference held in San Francisco, Rickman gave a presentation entitled Silicon Photonics: Bigger is Better. His talk outlined the advantages of Rockley’s use of three-micron-wide optical waveguides, bucking the industry trend of using relatively advanced CMOS processes to make silicon photonics components.
Rickman describes as seductive the idea of using 45nm CMOS for optical waveguides.“These things exist and work but people are thinking of them in the same physics that have driven microelectronics,” he says. Moving to ever-smaller feature sizes may have driven Moore’s Law but using waveguide dimensions that are smaller than the wavelength of light makes things trickier.
To make his point, he plots the effective index of a waveguide against its size in microns. The effective index is a unitless measure - a ratio of a phase delay in a unit length of a waveguide relative to the phase delay in a vacuum. “Once you get below one micron, you get a waveguide that is highly polarisation-dependent and just a small variation in the size of the waveguide has a huge variation in the effective index,” says Rickman.
Such variations translate to inaccuracies in the operating wavelength. This impacts the accuracy of circuits, for example, arrayed-waveguide gratings built using waveguides to multiplex and demultiplex light for wavelength-division multiplexing (WDM).
“Above one micron is where you want to operate, where you can manufacture with a few percent variation in the width and height of a waveguide,” says Rickman.“But the minute you go below one micron, in order to hit the wavelength registration that you need for WDM, you have got to control the [waveguide’s] film thickness and line thickness to fractions of a percent.” A level of accuracy that the semiconductor industry cannot match, he says.
A 100GHz WDM channel equates to 0.8nm when expressed using a wavelength scale. “In our technology, you can easily get a wavelength registration on a WDM grid of less than 0.1nm,” says Rickman. “Exactly the same manufacturing technology applied to smaller waveguides is 25 times worse - the variation is 2.5nm.”
Moreover, WDM technology is becoming increasingly important in the data centre. The 100-gigabit PSM4 uses a single wavelength, the CWDM4 uses four, while the newer CWDM8 MSA for 400 gigabit uses eight wavelengths. “In telecom, 90-plus wavelengths can be used; the same thing will come to pass in the years to come in data centre devices,” he says.
Rockley also claims it has a compact modulator that is 50 times smaller than competing modulators despite them being implemented using nanometer feature sizes.
We set out to generate a platform that would be pervasive across communications, new forms of advanced computing, optical signal processing and a whole range of sensor applications
Opto-ASIC reference design
Rockley’s first platform technology example is its Opto-ASIC reference design. The design integrates silicon photonics-based transceivers with an in-house 2 billion transistor switch chip all in one package. Rockley demonstrated the technology at OFC 2017.
“If you look around, this is something the industry says is going to happen but there isn't a single practical instantiation of it,” says Rickman who points out that, like the semiconductor industry, very often a reference design needs to be built to demonstrate the technology to customers.“So we built a complete reference design - it is called Topanga - an optical-packaged switch solution,” he says.
Despite developing a terabyte-class packet processor, Rockley does not intend to compete with the established switch-chip players. The investment needed to produce a leading edge device and remain relevant is simply too great, he says.
Rockley has demonstrated its in-package design to relevant companies. “It is going very well but nothing we can say publicly,” says Rickman.
New Markets
Rockley is also pursuing opportunities beyond telecom and datacom.
“We set out to generate a platform that would be pervasive across communications, new forms of advanced computing, optical signal processing and a whole range of sensor applications,” says Rickman.
Using silicon photonics for sensors is generating a lot of interest. “We see these markets starting to emerge and they are larger than the data centre and communications markets,” he says. “A lot of these things are not in the public domain so it is very difficult to report on.”
Moreover, the company’s believes its technology gives it an advantage for such applications. “When we look across the other application areas, we don’t see the small waveguide platforms being able to compete,” says Rickman. Such applications can use relatively high power levels that exceed what the smaller waveguides can handle.
Rockley is sequencing the markets it will address. “We’ve chosen an approach where we have looked at the best match of the platform to the best opportunities and put them in an order that makes sense,” says Rickman.
Rockley Photonics represent Rickman’s third effort to bring silicon photonics to the marketplace.Bookham Technology, the first company he founded, build different prototypes in several different areas but the market wasn't ready. In 2005 he joined start-up Kotura as a board member. “A huge amount of learning happened and then what Rockley represented was the opportunity to start all over again with a clean sheet of paper but with all that experience,” says Rickman.
Back in 2013, Rockley saw certain opportunities for its platform approach and what has happened since is that their maturity and relevance has increased dramatically.
“Like all things it is always down to timing,” says Rickman. “The market is vastly bigger and much more ready than it was in the Bookham days.”
Heterogeneous integration comes of age
Silicon photonics luminaries series
Interview 7: Professor John Bowers
August has been a notable month for John Bowers.
Juniper Networks announced its intention to acquire Aurrion, the US silicon photonics start-up that Bowers co-founded with Alexander Fang. And Intel, a company Bowers worked with on a hybrid integration laser-bonding technique, unveiled its first 100-gigabit silicon photonics transceivers.
Professor John BowersBower, a professor in the Department of Electrical and Computer Engineering at the University of California, Santa Barbara (UCSB), first started working in photonics in 1981 while at AT&T Bell Labs.
When he became interested in silicon photonics, it still lacked a good modulator and laser. "If you don't have a laser and a modulator, or a directly modulated laser, it is not a very interesting chip,” says Bowers. "So I started thinking how to do that."
Bowers contacted Mario Paniccia, who headed Intel’s silicon photonics programme at the time, and said: “What if we can integrate a laser? I think there is a good way to do it.” The resulting approach, known as heterogeneous integration, is one that both Intel and Aurrion embraced and since developed.
This is a key Bowers trait, says Aurrion co-founder, Fang: he just knows what problems to work on.
"John came up with the concept of the hybrid laser very early on," says Fang. "Recall that, at that time, silicon photonics was viewed as nothing more than people making plasma-effect phase shifters and simple passive devices. John just cut to the chase and went after combining III-V materials with silicon."
If you look at the major companies with strong photonics activities, you’ll find a leader in that group that was developed under John’s training
Fang also highlights Bowers' management skills. “John can pick players and run teams,” says Fang, who describes himself as one of those privileged to graduate out of Bowers’ research group at UCSB.
“You find yourself in an environment where John picks a team of sharp folk with complementary skills and domain expertise to solve a problem that John determines as important and has some insight on how to solve it,” says Fang. “If we look like we are going to drive off the road, he nudges with a good mix of insight, fear, and humour.”
It has resulted in some of the best trained independent thinkers and leaders in the industry, says Fang: “If you look at the major companies with strong photonics activities, you’ll find a leader in that group that was developed under John’s training”.
Silicon photonics
Bowers defines silicon photonics as photonic devices on a silicon substrate fabricated in a CMOS facility.
“Silicon photonics is not about using silicon for everything; that misses the point,” says Bowers. “The key element is using silicon as a substrate - 12-inch wafers and not 2- or 3-inch wafers - and having all the process capability a modern silicon CMOS facility brings.” These capabilities include not just wafer processing but also advanced testing and packaging.
The world is about to change and I don't think people have quite figured that out
“If you go to an advanced packaging house, they don't do 6-inch wafers and I don't know of indium phosphide and gallium arsenide wafers larger than 6 inches,” says Bowers. “The only solution is to go to silicon; that is the revolution that hasn't happened yet but it is happening now.”
Bowers adds that everything Aurrion does, there is automated test along the way. "And I think you have others; Luxtera has done a great job as well at wafer-level test and packaging," he says. "The world is about to change and I don't think people have quite figured that out."
Working with Intel was an eye-opener for Bowers, especially the process controls it applies to chip-making.
“They worry about distributions and yields, and it is clear why there are seven billion transistors on a chip and that chip will yield,” says Bowers. “When you apply that to photonics, it will take it to a whole new level.” Indeed, Bowers foresees photonics transfering to silicon.
Bowers highlights the fairly complex chips now being developed using silicon photonics.
“We have done a 2D scanner - a 32-element phased array - something one could never do in optics unless it was integrated all on one chip,” he says. The phased-array chip comprises 160 elements and is physically quite large.
This is another benefit of using 12-inch silicon wafers and fabricating the circuits in a CMOS facility. “You are not going to cost-effectively do that in indium phosphide, which I've worked on for the last 30 years,” says Bowers.
Another complex device developed at UCSB is a 2.54-terabit network-on-a-chip. “This is a larger capacity than anyone has done on any substrate,” he says.
Infinera’s latest photonic integrated circuit (PIC), for example, has a transport capacity of up to 2.4 terabit-per-second. That said, Bowers stresses that the network-on-a-chip is a research presentation while Infinera’s PIC is a commercial device.
Heterogeneous integration
Heterogeneous integration involves bonding materials such as III-V compounds onto silicon.
Bowers first worked on III-V bonding with HP to make longer wavelength - 1310nm and 1550nm - VCSELs. “We had been bonding indium phosphide and gallium arsenide to solve a fundamental problem that indium phosphide does not make good mirrors,” he says. “So I was pretty confident we could bond III-V to silicon to add gain to silicon photonics to then add all the laser capability.”
Bonding to silicon is attractive as it enables the integration of optical features that haven't been widely integrated onto any other platform, says Bowers. These include not only lasers but other active devices such as modulators and photo-detectors, as well as passive functions such as isolators and circulators.
One concern raised about heterogeneous integration and the use of III-V materials is the risk of contamination of a CMOS fabrication line.
Bowers points out that the approached used does not impact the front end of the fabrication, where silicon wafers are etched and waveguides formed. The III-V material is bonded to the wafer at the fab’s back end, the stage where metallisation occurs when making a CMOS chip.
The leading chipmakers are also experimenting with III-V materials to create faster digital devices due to their higher electron mobility. “This is part of the natural evolution of CMOS,” he says. It remains unclear if this will be adopted, but it is possible that a 5nm CMOS node will use indium phosphide.
“All the CMOS houses are doing lots of work on III-V and silicon,” says Bowers. “They have figured out how to control that contamination issue.”
New capabilities
Bowers and his team have already demonstrated the integration of new optical functions on silicon.
“Neither silicon nor indium phosphide has an isolator and one always has to use an external YIG (yttrium iron garnet) isolator to reduce the reflection sensitivity of things like widely tunable lasers,” says Bower.
His team has developed a way to bond a YIG onto silicon using the same techniques it uses for bonding III-V materials. The result is an integrated isolator device with 32dB isolation and a 2dB insertion loss, a level of performance matching those of discrete isolators.
Incorporating such functionality onto silicon creates new possibilities. “We have a paper coming out that features a 6-port circulator,” says Bowers. “It is not a tool that the community can use yet because it has never been made before but we can do that on silicon now,” he says. “That is a good new capability.”
Superior performance
Bowers stresses that heterogeneous integration can also result in optical performance superior to a III-V design alone. He cites as an example how using a silicon nitride waveguide, with its lower loss that indium phosphide or gallium arsenide, can create high-quality Q-resonators.
A Q-resonator can be viewed as a form of filter. Bowers' group have demonstrated one with a Q of 80 million. “That makes it very sensitive to a variety of things,” he says. One example is for sensors, using a Q resonator with a laser and detector to form a spectrometer.
His researchers have also integrated the Q resonator with a laser to make a widely tunable device that has a very narrow line-width: some 40kHz wide. This is a narrower than the line-width of commercially-available tunable lasers and exceeds what can be done with indium phosphide alone, he says.
Challenges
Bowers, like other silicon photonics luminaries, highlights the issues of automated packaging and automated testing, as important challenges facing silicon photonics. “Taking 10,000s of transceivers and bringing all the advanced technology - not just processing but test and packaging - that are being developed for cell phones,” he says.
Too much of photonics today is based on gold boxes and expensive transceivers. “Where Aurrion and Intel are going is getting silicon photonics to the point where photonics will be ubiquitous, cheap and high yielding,” he says. This trend is even evident with his university work. The 400-element 2.54-terabit network-on-a-chip has very high laser yields, as are its passive yields, he says.
“So, effectively, what silicon photonics can do is going up very rapidly,“ says Bowers. “If you can put it in the hands of a real CMOS player like Intel or the companies that Aurrion uses, it is going to take photonics to a whole new area that people would not have thought possible in terms of complexity.”
Yet Bowers is also pragmatic. “It still takes time,” he says. “You can demonstrate an idea, but it takes time to make it viable commercially.”
He points to the recently announced switch from Oracle that uses mid-board optics. “That is a commercial product out there now,” he says. “But is it silicon photonics? No, it is VCSEL-based; that is the battle going on now.”
VCSELs have won the initial battle in the data centre but the amount of integration the technology can support is limited. Once designers move to wavelength-division multiplexing to get to higher capacities, where planar technology is required to combine and separate the different wavelengths efficiently, that is when silicon has an advantage, he says.
The battle at 100 gigabit between VCSELs and silicon photonics is also one that Bowers believes silicon photonics will eventually win. But at 400 gigabit and one terabit, there is no way to do that using VCSELs, he says.
Status
The real win for silicon photonics is when optics moves from transceivers at the edge of the board to mid-board and eventually are integrated with a chip in the same package, he says.
Advanced chips such as switch silicon for the data centre are running into an input-output problem. There are only so many 25 gigabit-per-second signals a chip can support. Each signal, sent down a trace on a printed circuit board, typically requires equalisation circuitry at each end and that consumes power.
Most of the photonics industry has focused on telecom and datacom, and justifiably so. The next big thing will happen in the area of sensors.
A large IC packaged as a ball grid array may have as many as 5,000 bumps (balls) that are interfaced to the printed circuit board. Using photonics can boost the overall bandwidth coming on and off the chip.
“With photonics, and in particular when we integrate the laser as well as the modulator, the world doesn't see it as a photonics chip, it's an electronics chip, it just turns out that some of those bumps are optical ones and they provide much more efficient transmission of data and at much lower power,” say Bowers. A 100 terabit of even a 1000 terabit - a petabit - switch chip then becomes possible. This is not possible electrically but it is possible by integrating photonics inside the package or on the chip itself, he says.
“That is the big win eventually and that is where we help electronics extend Moore’s law,” says Bowers.
And as silicon photonics matures, other applications will emerge - More than Moore’s law - like the use of photonics for sensors.
“Most of the photonics industry has focused on telecom and datacom, and justifiably so,” says Bowers. “The next big thing will happen in the area of sensors.”
Professor Bowers was interviewed before the Juniper Networks announcement
Imec gears up for the Internet of Things economy
It is the imec's CEO's first trip to Israel and around us the room is being prepared for an afternoon of presentations the Belgium nanoelectronics research centre will give on its work in such areas as the Internet of Things and 5G wireless to an audience of Israeli start-ups and entrepreneurs.
Luc Van den hove
iMinds merger
Imec announced in February its plan to merge with iMinds, a Belgium research centre specialising in systems software and security, a move that will add 1,000 staff to imec's 2,500 researchers.
At first glance, the world-renown semiconductor process technology R&D centre joining forces with a systems house is a surprising move. But for Van den hove, it is a natural development as the company continues to grow from its technology origins to include systems-based research.
"Over the last 15 years we have built up more activities at the system level," he says. "These include everything related to the Internet of Things - our wireless and sensor programmes; we have a very strong programme on biomedical applications, which we sometimes refer to as the Internet of Healthy Things - wearable and diagnostics devices, but always leveraging our core competency in process technology."
Imec is also active in energy research: solar cells, power devices and now battery technology.
For many of these systems R&D programmes, an increasing challenge is managing data. "If we think about wearable devices, they collect data all the time, so we need to build up expertise in data fusion and data science topics," says Van den hove. There is also the issue of data security, especially regarding personal medical data. Many security solutions are embedded in software, says Van den hove, but hardware also plays a role.
Imec expects the Internet of Things to generate massive amounts of data, and more and more intelligence will need to be embedded at different levels in the network
"It just so happens that next to imec we have iMinds, a research centre that has top expertise in these areas [data and security]," says Van den hove. "Rather than compete with them, we felt it made more sense to just merge."
The merger also reflects the emergence of the Internet of Things economy, he says, where not only will there be software development but also hardware innovation: "You need much more hardware-software co-development". The merger is expected to be completed in the summer.
Internet of Things
Imec expects the Internet of Things to generate massive amounts of data, and more and more intelligence will need to be embedded at different levels in the network.
"Some people refer to it as the fog - you have the cloud and then the fog, which brings more data processing into the lower parts of the network," says Van den hove. "We refer to it as the Intuitive Internet of Things with intelligence being built into the sensor nodes, and these nodes will understand what the user needs; it is more than just measuring and sending everything to the cloud."
Van den hove says some in the industry believe that these sensors will be made in cheap, older-generation chip technologies and that processing will be performed in data centres. "We don't think so," he says. "And as we build in more intelligence, the sensors will need more sophisticated semiconductors."
Imec's belief is that the Internet of Things will be a driver for the full spectrum of semiconductor technologies. "This includes the high-end [process] nodes, not only for servers but for sophisticated sensors," he says.
"In the previous waves of innovation, you had the big companies dominating everything," he says. "With the Internet of Things, we are going to address so many different markets - all the industrial sectors will get innovation from the Internet of Things." There will be opportunities for the big players but there will also be many niche markets addressed by start-ups and small to medium enterprises.
Imec's trip to Israel is in response to the country's many start-ups and its entrepreneurship. "Especially now with our wish to be more active in the Internet of Things, we are going to work more with start-ups and support them," he says. "I believe Israel is an extremely interesting area for us in the broad scope of the Internet of Things: in wireless and all these new applications."
Herzliya
Semiconductor roadmap
Van den hove's background is in semiconductor process technology. He highlights the consolidation going on in the chip industry due, in part, to the CMOS feature nodes becoming more complex and requiring greater R&D expenditure to develop, but this is a story he has heard throughout his career.
"It always becomes more difficult - that is Moore's law - and [chip] volumes compensate for those challenges," says Van den hove. When he started his career 30 years ago the outlook was that Moore's law would end in 10 years' time. "If I talk to my core CMOS experts, the outlook is still 10 years," he says.
Imec is working on 7nm, 5nm and 3nm feature-size CMOS process technologies. "We see a clear roadmap to get there," he says. He expects the third dimension and stacking will be used more extensively, but he does not foresee the need for new materials like graphene or carbon nanotubes being used for the 3nm process node.
Imec is pursuing finFET transistor technology and this could be turned 90 degrees to become a vertical nanowire, he says. "But this is going to be based on silicon and maybe some compound semiconductors like germanium and III-V materials added on top of silicon." The imec CEO believes carbon-based materials will appear only after 3nm.
"The one thing that has to happen is that we have a cost-effective lithography technique and so EUV [extreme ultraviolet lithography] needs to make progress," he says. Here too he is upbeat pointing to the significant progress made in this area in the last year. "I think we are now very close to real introduction and manufacturing," he says.
We see strong [silicon photonics] opportunities for optical interconnect and that is one of our biggest activities, but also sensor technology, particularly in the medical domain
Silicon Photonics
Silicon photonics is another active research area with some 200 staff at imec and at its associated laboratory at Ghent university. "We see strong opportunities for optical interconnect and that is one of our biggest activities, but also sensor technology, particularly in the medical domain," he says.
Imec views silicon photonics as an evolutionary technology. "Photonics is being used at a certain level of a system now and, step by step, it will get closer to the chip," he says. "We are focussing more on when it will be on the board and on the chip."
Van den hove talks about integrating the photonics on a silicon interposer platform to create a cost-effective solution for the printed circuit board and chip levels. For him, first applications of such technology will be at the highest-end technologies of the data centre.
For biomedical sensors, silicon photonics is a very good detector technology. "You can grow molecules on top of the photonic components and by shining light through them you can perform spectroscopy; the solution is extremely sensitive and we are using it for many biomedical applications," he says.
Looking forward, what most excites Van den hove is the opportunity semiconductor technology has to bring innovation to so many industrial sectors: "Semiconductors have created a fantastic revolution is the way we communicate and compute but now we have an opportunity to bring innovation to nearly all segments of industry".
He cites medical applications as one example. "We all know people that have suffered from cancer in our family, if we can make a device that would detect cancer at a very early stage, it would have an enormous impact on our lives."
Van den hove says that while semiconductors is a mature technology, what is happening now is that semiconductors will miniaturise some of the diagnostics devices just like has happened with the cellular phone.
"We are developing a single chip that will allow us to do a full blood analysis in 10 minutes," he says. DNA sequencing will also become a routine procedure when visiting a doctor. "That is all going to be enabled by semiconductor technology."
Such developments is also a reflection of how various technologies are coming together: the combination of photonics with semiconductors, and the computing now available.
Imec is developing a disposable chip designed to find tumour cells in the blood that requires the analysis of thousands of images per second. "The chip is disposable but the calculations will be done on a computer, but it is only with the most advanced technology that you can do that," says Van den hove.