Lithography and MEMS

User community

At the recent HARMST 2003 conference held in Monterey USA, more than 300 researchers from more than 16 countries gathered to discuss the science, technology and commercialization of High Aspect Ratio Micro Systems (HARMST) and, in particular, LIGA, a German acronym denoting processes based on lithography, electroplating, and replication by injection moulding or embossing.

The lithography facility at the Australian synchrotron will be established to provide high-volume production. It will incorporate an advanced design of scanner and will work in tandem with the nearby MiniFAB facility. It will form a centre of intense activity that is expected to be the focus of considerable international interest.

Several local industrial users have already expressed an interest in exploring the product development potential of LIGA at the Australian Synchrotron. These include Masterfoods, Varian, Micromachines Ltd, and AMCOR. All of these are pursuing their interests through MiniFAB Pty Ltd, a private venture that has expressed early support for the industrial applications of LIGA. It operates supporting infrastructure such as clean rooms, mask aligner, laser ablation, deposition and moulding.

The CRC for Micro Technology has been developing an industrial capacity in LIGA assisted by the Australian Synchrotron Research Program (ASRP) . Industrial users require that the LIGA process be specification driven; it must be able to deliver a reliable, guaranteed service. Such a service can be provided if it is underpinned by a sound understanding of the fundamentals of LIGA, and can only remain globally competitve if supported by a strong scientific R&D program.

Preliminary discussions with the LIGA representatives of the new Canadian Light Source and the UK Diamond facility indicate that they would partner in this development, with the aim of building three scanners for installation at each of the new synchrotrons.

Research applications

New applications being researched internationally include:

• fuel cell development
• deposition nozzles
• cochlear implant moulds
• accelerometer sensors
• micro relays
• x-ray lens fabrication
• micro gas bearings
• ink jet printers
• micro spectrometer development
• micro-optic fabrication
• micro medical devices such as forceps, tweezers, and micro needle arrays
• direct synchrotron machining of PTFE
• variable reluctance stepping motors
• conformal atomic layer deposition films

There is substantial effort and debate in the local and international LIGA community concerning developments in modelling of the full LIGA process, including electroforming and moulding, as well as metrology, characterization, resist development, and the development of infrastructure. Theoretical models for the exposure have only been developed for PMMA and the complexities of secondary electron emission, scattering processes, and others remain important in gaining a fundamental understanding of the x-ray interaction with resists.