Lighting the Path to Exascale Computing

New chip technology unveiled today by IBM integrates electrical and optical devices on the same piece of silicon, enabling computer chips to communicate using light pulses instead of electrical signals. The advance could bring exascale computers — machines 1000 times faster than today's best systems — closer to reality.

The new technology, called CMOS integrated silicon nanophotonics, is the result of a decade of development at its research labs, IBM said. Integrating optical devices and functions directly onto a silicon chip enables a more than 10X improvement in integration density than is feasible with current manufacuring techniques.

IBM's new CMOS integrated silicon nanophotonics chip technology integrates electrical and optical devices on the same piece of silicon, enabling computer chips to communicate using pulses of light (instead of electrical signals), which enables a 10X improvement in integration density and produces smaller, faster and more power-efficient chips than is possible with conventional technologies.

IBM anticipates that silicon nanophotonics will dramatically increase the speed and performance between chips, and further its ambitious Exascale computing program, which is aimed at developing a supercomputer that can perform one million trillion calculations — or an Exaflop — in a single second. An Exascale supercomputer will be approximately 1000 times faster than the fastest machine today (See Road to Exascale Computers).

In addition to combining electrical and optical devices on a single chip, the new technology can be produced on the front-end of a standard CMOS manufacturing line and requires no new or special tooling. With this approach, silicon transistors can share the same silicon layer with silicon nanophotonics devices.

To make this approach possible, a suite of integrated ultracompact active and passive silicon nanophotonics devices were developed that are all scaled down to the diffraction limit — the smallest size that dielectric optics can afford.

“Our CMOS integrated nanophotonics breakthrough promises unprecedented increases in silicon chip function and performance via ubiquitous low-power optical communications between racks, modules, chips or even within a single chip itself,” said Dr. Yurii A. Vlasov, manager of the Silicon Nanophotonics Department at IBM Research. “The next step in this advancement is to establishing manufacturability of this process in a commercial foundry using IBM deeply scaled CMOS processes.”

IBM scientists (l-r) Yurii Vlasov, William Green and Solomon Assefa unveiled a new CMOS integrated silicon nanophotonics chip technology that integrates electrical and optical devices on the same piece of silicon, enabling computer chips to communicate using pulses of light instead of electrical signals. (Photo: Bob Goldberg/Feature Photo Service)

By adding just a few more processing modules to a standard CMOS fabrication flow, the technology enables a variety of silicon nanophotonics components, such as: modulators, germanium photodetectors and ultracompact wavelength-division multiplexers to be integrated with high-performance analog and digital CMOS circuitry. As a result, single-chip optical communications transceivers can now be manufactured in a standard CMOS foundry, rather than assembled from multiple parts made with expensive compound semiconductor technology.

The density of optical and electrical integration demonstrated is unprecedented, the company said – a single transceiver channel with all accompanying optical and electrical circuitry occupies only 0.5mm² – 10 times smaller than previously announced by others. The technology is amenable for building single-chip transceivers with area as small as 4x4mm² that can receive and transmit over Terabits per second that is over a trillion bits per second.

Other milestones the company achieved while developing CMOS integrated silicon nanophotonics include:

In March 2010, the announcement of a germanium avalanche photodetector working at 40 Gb/s with CMOS compatible voltages as low as 1.5 V. This was the last piece of the puzzle that completes the prior development of the “nanophotonics toolbox” of devices necessary to build the on-chip interconnects (See Light Replacing Wires in Chips). In March 2008, the company announced the world’s tiniest nanophotonic switch for “directing traffic” in on-chip optical communications, ensuring that optical messages can be efficiently routed (See Nano Switch Routes Light).

For more information, visit: www.research.ibm.com/photonics