News and Reviews (Sept 2018)

On-Chip 3D Printing

Direct fabrication of 3D microparts on integrated circuits saves packaging costs and time

Snapshot of the 3D printing process of a hemispherical lens on a chip. Inset: Print simulation of the 3D component.

For growing demands, e.g. in high-speed data transfer and portable medical devices, more and more functional parts have to be accommodated in ever smaller spaces on chips. Currently, the production of integrated circuits (ICs) and microelectromechanical systems (MEMS) requires different manufacturing methods and multiple process steps for assembling different components on one microchip.

Now, with Nanoscribe’s Photonic Professional GT 3D printers one can print and integrate microscopic parts directly on integrated circuits such as micro-lenses onto photonic circuits. These groundbreaking 3D printers fabricate structures with complex geometry, feature sizes from hundreds of nanometers and object dimensions of up to several millimeters.

Optical microscope image of 3D-printed hemispherical lenses on a photonic chip.

3D-printed parts are produced in a single printing step and on a scale which was inaccessible to 3D printing before. The advantages of standard additive manufacturing such as full 3D design freedom and a straightforward workflow from CAD model to final part are available to nano- and microfabrication, speeding up the design iteration cycles and saving time and costs during product development. The possibility of on-chip printing opens new doors to the production of nano- and microscale 3D components in situ, exactly where needed.

The following movie demonstrates how one can fabricate smallest functional components directly on photonic circuits and deformable structures on MEMS actuators by means of a Photonic Professional GT device. As an example of on-chip 3D printing, micro-lenses are produced directly onto photonic ICs (Img 1). A series of hemispherical micro-lenses is fabricated on top of grating couplers of a photonic chip (Img 2). The micro-lenses are fabricated in a single and continuous print run without the need to align and mount the finished micro-optics mechanically onto the pre-structured microchip. This approach can reduce costs in packaging avoiding calibration, pick and place as well as curing-based fixing procedures.

Technology behind on-chip 3D printing
Two-photon polymerization is the basis for Nanoscribe’s 3D microprinting technology. In this printing process a laser exposes a photosensitive resin by means of a high-numerical aperture objective along a trajectory and layer-by-layer following a CAD design. The material solidifies only in the laser focus allowing to additively build up nearly arbitrary 3D structures with even submicron features. The new update of on-chip printing expands the applications on pre-manufactured circuits and opens new avenues for the production of integrated circuits.