The wire bond is adapted to the position and orientation of the chips. Figure: N. Lindenmann and G. Balthasar |
A
team of Karlsruhe Institute of Technology researchers directed by Professor Christian Koos has
succeeded in developing a novel optical connection between semiconductor
chips. “Photonic wire bonding” reaches data transmission rates in the
range of several terabits per second and is suited perfectly for
production on the industrial scale. In the future, this technology may
be used in high-performance emitter-receiver systems for optical data
transmission and, thus, contribute to reducing energy consumption of the
internet. The scientists published their results in the journal Optics
Express.
Communication
processes can be made quicker and more energy-efficient with photonic
components. Development of high-performance optical emitters and
receivers integrated on microchips has already reached a high level.
However, there have not yet been any satisfactory possibilities of
bridging semiconductor chips optically.
“The
biggest difficulty consists in aligning the chips precisely such that
the waveguides meet,“ explains Christian Koos, professor at the KIT
Institutes of Photonics and Quantum Electronics (IPQ) and of
Microstructure Technology (IMT) as well as member of the Center for
Functional Nanostructures (CFN).
The
team under Christian Koos tackles this problem from the other side: The
researchers first fix the chips and then structure a polymer-based
optical waveguide in a perfectly fitting manner. To adapt the
interconnection to the position and orientation of the chip, the
scientists developed a method for the three-dimensional structuring of
an optical waveguide. They used so-called two-photon polymerization
which reaches a high resolution. A femtosecond laser writes the
free-form waveguide structure directly into a polymer that is located on
the surface of the chip. For this purpose, the KIT researchers use a
laser lithography system made by the Nanoscribe company, a spinoff of
KIT.
Prototypes
of the photonic wire bonds reached very small losses and a very high
transmission bandwidth in the range of infrared telecommunication
wavelengths around 1.55 micrometers. In first experiments, the
researchers already demonstrated data transmission rates in excess of 5
terabits per second. Potential applications of photonic wire bonds lie
in complex emitter-receiver systems for optical telecommunication as
well as in sensor and measurement technology. As the highly precise
orientation of the chips in manufacturing is no longer required, the
process is particularly suited for the automatic production of large
series. KIT researchers now plan to transfer this technology to
industrial application in cooperation with partner companies.
Photonic wire bonding: a novel concept for chip-scale interconnects
