Ireland's Tyndall National Institute (based at University College Cork) is leading the European consortium TOP-HIT (Transfer-print OPerations for Heterogeneous INtegration) to develop novel technology that will address the challenge of integrating components of different materials in large volumes at the semiconductor scale.
Funded with more than €5m under the European Union's Horizon 2020 program for Smart System Integration and running from 2015 to 2018, the TOPHIT project uses micro-transfer printing (μTP) technology, which allows a set of potentially many thousands of devices at a time to be taken from one semiconductor wafer and stamped onto another wafer.
Picture: Schematic of the micro-transfer print (μTP) process.
As an example, a small platelet of an expensive material can be picked up with a stamp and transfer printed onto a larger surface of another (less expensive) material, on which all electrical and optical waveguide interconnections can then be made. Or, light-emitting devices (such as LEDs or lasers) can be printed onto a material that is more suitable for electronic signal processing. It is even possible to print several types of devices onto the same substrate material to combine, for example, light sources, detectors and signal processing all on the same platform. Hence, a system-on-a-chip - a photonic integrated circuit (PIC) combining devices made of different materials - can be built up. Printed platelets are typically a few microns thick, and can be printed with a placement precision of about 1μm.
"The transfer print process, by combining diverse optical, electronic and other functional materials, opens up an enormous range of possibilities for new devices with embedded functionality," says project coordinator Brian Corbett (principal investigator at Tyndall). "This will lead to more compact chips and systems for a variety of applications, such as telecommunications, smart sensing, biomedical sensing and data storage, but the key breakthrough will be the application of micro-transfer-printing to address the challenge of integrating non-compatible components in large volumes at the semiconductor wafer level, eliminating the need for current inelegant integration processes such as wire-bonding," he adds.
The consortium partners provide complementary expertise: Ireland-based X-Celeprint is a manufacturer of transfer printing equipment that can print many devices simultaneously, and provides the printing expertise. Belgium-based nanoelectronics research center Imec (which employs over 1500 people) has its own X-Celeprint equipment, and provides the silicon photonics platforms that form the basis for the photonic products. Belgium-based photonics company Caliopa Huawei develops optical components and circuits for telecoms applications. The Centre for Integrated Photonics (CIP, a subsidiary of Huawei, in the UK) develops indium phosphide (InP)-based components and circuits for telecoms applications. Germany-based analog/mixed-signal and MEMS foundry X-FAB will develop new processes to provide wafers with components that can be transfer printed (and will add this capability to its existing portfolio of modular foundry processes). Seagate is a manufacturer of hard-disk drives and storage solutions whose facility in Northern Ireland ships more than 500 million read-write heads annually. Ireland's Tyndall National Institute provides designs and components that can be transfer printed by X-Celeprint onto platforms provided by Imec and X-FAB.
