Schematic of the 3D printing process and an image of a manufactured microstructure. |
Production
of silicon micro- and nano-sensors with today’s technologies requires a
full-scale clean-room laboratory costing millions of euros—facilities
that few organisations can afford. What’s more, integrated-circuit
manufacturing technologies used in sensor production are highly
standardised processes, optimised for extremely large production volumes
of hundreds of millions of devices per year. These sensors, known as
microelectromechanical systems (MEMS), are engineered from thin slices
of silicon, the same material used to manufacture integrated circuits
and other micro-sized electronic devices.
Researchers
at KTH Microsystem Technology have demonstrated a manufacturing concept
that could pave the way toward simple, inexpensive “printing” of 3D
silicon structures.
“It
could be made very easy, flexible and cheap compared with today’s
manufacturing processes. All you’ll need is a 3D printer and someone to
draw the structure in a drafting program on a computer,” says Frank
Niklaus, Associate Professor at KTH Microsystem Technology.
The
new manufacturing technology consists of a layer-by-layer process for
defining 3D patterns in silicon, using focused ion beam writing followed
by silicon deposition. The layered 3D silicon structures are defined by
repeating these two steps over and over, followed by a final etching
step in which the excess silicon material is dissolved away. The
researchers note, however, that the system has so far only been tested
manually on relatively simple structures, and that more development lies
ahead to implement the concept in a manufacturing tool called a 3D
printer.
“In
a future manufacturing process, the structure would first be designed
in a 3D drawing programme. The drawing is then sent to a 3D printer that
recreates the structure in silicon, layer by layer from the bottom up,”
explains Niklaus.
In
2011, Frank Niklaus received a grant of EUR 1.5 million (about SEK 15
million) from the European Research Council for his research on new
manufacturing paradigms for micro- and nanosystems.
Now
the researchers are working to refine the process on a larger scale,
and they plan to develop a 3D printer that enables the creation of
complex 3D silicon nanostructures. The next step is to commercialise the
manufacturing technology in collaboration with partners from industry.
Sensors
that detect the orientation and movements of mobile phones or airbag
systems in cars are just a few examples of the applications for micro
and nano-scale sensors.
“Just
imagine all the new applications that people could come up with if they
had an easy and cheap way to manufacture nano-structures for sensors
and devices. With this tool, we want to enable smaller markets and
organisations to advance sensors and other technologies in ways that we
can’t even imagine today. I’d compare it to the way affordable computing
opened things up for mass innovation in information technologies over
the last 30 years or so.”
In
June 2012, the team at KTH’s Microsystem Technology Lab and researchers
in the university’s laboratories for Engineering Materials Physics and
Integrated Devices and Circuits had the results of their research
published as an article entitled “3D Free-Form Patterning of Silicon by
Ion Implantation, Silicon Deposition, and Selective Silicon Etching” in Advanced Functional Materials, a leading journal in the field.
