New research consortium Q2M to develop novel microfabrication methods

Citation

(2007), "New research consortium Q2M to develop novel microfabrication methods", Sensor Review, Vol. 27 No. 1. https://doi.org/10.1108/sr.2007.08727aab.002

New research consortium Q2M to develop novel microfabrication methods

New research consortium Q2M to develop novel microfabrication methods

Cranfield University have become partners in a new research consortium called Q2M or “Quality to Micro” which has been set up to address some of the key issues encountered in batch manufacturing of micro-scale devices. The aim is to develop generic micro- fabrication technologies that can be used to build micro-mechanical and micro- optical devices that consist of several different component parts and which are made from several different materials. The target applications are microvalves for fluids and gases, spatial light modulators and wireless communication components. The project is a Strategically Targeted Research Project supported by the European Union under the 6th Framework programme and the total budget shared by the 12 partners is e3.2 million.

The project will be run at Cranfield by Stephen Wilson and Paul Kirby in the Microsystems and Nanotechnology Centre, who will concentrate, respectively, on micro-scale piezoelectric ceramic components for valves and on systems integration of radio-frequency switches.

Micro-fabrication techniques are used for the production of a myriad of components and systems with feature sizes in the range from a few millimetres down to 100nm. Application fields include the automotive industry (airbag sensors, tire pressure sensors), telecom applications (switches and filters), publishing applications (printhead technology), medical applications (catheter based instruments) and biotechnical instrumentation (DNA analysis).

High quality materials, such as shape memory metals and polymers, piezo- ceramics and ultra-flat single crystalline layers, show excellent characteristics for sensor applications and micro-motion control. However, the mainstream micro-structuring techniques that have been developed from the micro- electronics industry cannot usually be applied where different types of materials are concerned. In this sense it can be said that the challenges faced in manufacturing micro-mechanical devices are arguably more difficult than they are for conventional integrated circuits. “Often the standard micro- fabrication techniques are incompatible with novel materials. This is one of the major bottlenecks for the development of novel applications and for widespread commercialisation.” says Dr Wilson. We therefore decided to work with Professor Wouter van der Wijngaart at the Stockholm Royal Institute of Technology (KTH) to create the Q2M Consortium with the aim of pushing the technology beyond its current barriers. We will follow two general strategies: using combinations of high quality materials to make novel structural components and developing novel transfer bonding methods. The latter represents a new departure in the technology. Whole layers of hundreds or thousands of individual components will be created together on a single wafer in such a way that they can later be transferred, individually or in groups, and bonded precisely in place alongside micro-electronic circuits. In this way, complicated systems of different micro-components can be created to make up a device (Figure 1).

Figure 1 Principle of successive multi-component transfer to build micro-scale devices on a chip

The new micro-fabrication approach is also attractive for incorporating non- silicon materials that offer enhanced performance and capability into microwave circuits, to meet the needs of the ever-increasing market for mobile communications. Over the last seven years Cranfield has developed several RF MEMS devices such as acoustic resonators, filters, and miniature mechanical switches that use piezoelectric thin films. Dr Paul Kirby explains, “To-date the application of these devices in circuits has been in the form of discrete components because these materials cannot be present during silicon processing. By being part of this project we hope to demonstrate a means of populating a microwave circuit with our components, without any danger of contamination. Integration of radio frequency switches for communications devices will be a further major topic of research at Cranfield under the Q2M programme.

The work at Cranfield builds on expertise gained through the EU Growth Project “Aeromems II” where Dr Wilson and Dr Renaud Jourdain worked alongside colleagues from the Precision Engineering Centre and in collaboration with the BAE Systems Advanced Technology Centre, to create a new micro-actuator for the purpose of aerodynamic flow control in passenger aircraft (Figure 2). The fabrication route created there was completely new, combining ultra-precision machining techniques with standard micro-fabrication processes such as photolithography. “This type of structure has not been attempted elsewhere and it serves to highlight the benefits of the unique range of research facilities and know-how that we have available at Cranfield.”

Figure 2 Multi-layer device wafer developed for Aeromems II – individual cantilevers are piezoelectric devices based on micro-machined stacks of PZT ceramic and titanium

The Q2M Consortium is comprised of academic partners and industrial companies engaged in technology development, each an expert and pioneer in a core aspect of the multidisciplinary scientific challenge. In addition, the group also includes a number of technology end-users who will anchor the work to real industrial needs, thereby creating the basis for further development and exploitation. The 12 partners are Royal Institute of Technology (project coordinator, KTH, Sweden), Cranfield University, Katholieke Universiteit Leuven (Belgium), Forschungszentrum Karlsruhe (FZK, Germany), Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V (IPMS, Germany), Pondus Instruments AB (Sweden), Micronic Laser Systems AB (Sweden), Steinbeis Transfer Centre ASICON (Germany), IBM Research Centre, Zurich CH, VTT – Technical Research Centre of Finland and LK Products also from Finland.

For further information, please visit: http://q2m.4m-net.org/Q2M_Home; contact: Dr Stephen Wilson, s.a.wilson@cranfield.ac.uk or Dr Paul Kirby, p.b.kirby@cranfield.ac.uk