P.G. Shao

Improvement in proton beam writing at the nano scale

Here we report on the progress of 3D nano machining using MeV protons. In proton beam (p-beam) writing a proton beam is typically focused down to a sub 100 nm spot size and scanned over a resist material (e.g. Su-8 or PMMA). Currently the scanning is performed using a magnetic scan coil which has an intrinsically long settling time. A new scanning system is introduced which employs electrostatic scanning and allows an increase in writing speed up to 2 orders of magnitude.

Nickel Injection Mould Fabrication via Proton Beam Writing and UV Lithography

For applications of injection mould fabrication in the field of MEMS, proton beam writing (PBW) and UV lithography are combined to manufacture 2 mm thick Ni moulds with sub-10 µm fine features in 10 µm deep fluidic channels. PBW is capable of writing micro and nano features with straight and smooth sidewalls with sub-10 nm RMS roughness, while UV lithography has the advantage of large area structuring through a mask. A newly developed positive resist maP1275 hv is presented in combination with PBW and UV lithography for Ni injection mould fabrication. Fine micro pillars with straight and smooth sidewalls have been achieved by PBW and linked with UV lithography into a microfluidic channel. The new resist is successfully removed after electroplating without compromising the Ni mould.

Sub Micron Poly-Dimethyl Siloxane (PDMS) Replication Using Proton Beam Fabricated Nickel Moulds

We present a process to fabricate Ni moulds on proton beam written (PBW) PMMA structures. These Ni mould are use to replicate PDMS lab on a chip devices featuring 300 nm details of high verticality, smooth sidewalls and high aspect ratios. The lifespan of the Ni mould can be extended and the functionality improved by means of introducing a 5 nm thick Teflon AF release layer. Following this method, PDMS chips have been fabricated for microfluidic experiments.