Micro-transfer printing: boosting large scale integration of diverse materials and devices

Tyndall National Institute, Cork, Ireland is leading a European consortium, called TOP-HIT, to develop novel technology that will address the challenge of integrating components of different materials in large volumes at the semi-conductor scale.

The TOP-HIT ("Transfer-print operations for heterogeneous integration") consortium uses micro-transfer printing (μTP), a technology that allows you to take a set of devices out of one semiconductor wafer and print these sparsely onto another wafer, transferring potentially many thousands of devices in each single transfer operation.

The following gives an example of how this technique can be used. You may take a small platelet of an expensive material, pick it up with a "stamp" (think of that platelet as being the ink attached to the stamp) and transfer it ("print it" ) with that same stamp onto a larger surface of another (cheaper) material, and then carry out all the electrical and optical waveguide interconnections on this second material. Or, you may print light emitting devices (such as light emitting diodes or lasers) 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. A "system-on-a-chip", a complex photonic integrated circuit combining devices made of different materials, can be built up in this way. Printed platelets are typically a few microns thick, and can be printed with a placement precision of about 1 µm.

Mr. Brian Corbett, principal investigator at Tyndall and coordinator of the project explained: "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. 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."

Provided by Tyndall National Institute