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Imec demos low-loss silicon photonics components

23 July 2012
Belgian research centre Imec is claiming a silicon photonics breakthrough with what it says is the world’s first realization of functional sub-100nm photonics components using optical lithography on 300-mm wafers.
Imec has been working on heterogeneous integration of optical components, using a variety of bonded materials connected by compact waveguides fashioned out of silicon-on-insulator (SOI) wafers.  The high-index contrast in SOI enables ultra-compact waveguides and cavities to be patterned using 193nm immersion lithography.

The compact optical waveguides have a very low propagation loss well below 1dB/cm, which is the lowest propagation loss ever reported in silicon wire waveguides, according to Imec. The Imec team also says they succeeded in demonstrating low phase errors on 450-nm arrayed waveguide gratings, proving that the process technology can yield a very uniform waveguide width within a device.

The work is part of Imec’s industrial affiliation program on optical I/O, which explores the use of photonics for realizing high-bandwidth I/O in high performance computing systems. The program is developing silicon photonics processes, devices and circuits using CMOS fabrication processes rather than lab-scale techniques such as e-beam lithography.

Imec patterned sub-wavelength size features and demonstrated optical fibre-chip couplers. By using 45nm mask technology and 193nm immersion lithography to pattern these features and devices, Imec was able to eliminate one patterning step in the device processing, resulting in a significant reduction of the processing cost.  This is an important step in bringing silicon photonics technology in line with CMOS industry standards, the company says.

“Our achievement with 193nm immersion lithography and 28nm CMOS processes on 300mm wafers is an important step in silicon photonics development to demonstrate the manufacturability of highly integrated components,” said Philippe Absil, director of the optical I/O program at Imec. “Possible applications are next-generation short-reach interconnects, which we expect to go into manufacturing by 2015.”

These results were obtained in cooperation with INTEC, Imec’s associated lab at the Ghent University, and with Imec’s key partners in its core CMOS programs: Globalfoundries, Intel, Micron, Panasonic, Samsung, TSMC, Elpida, SK Hynix, Fujitsu, Toshiba/Sandisk, and Sony.

By Pauline Rigby