Metrology concepts for a new generation of plasma manufacturing with atom-scale precision

This research proposal is targeted at addressing the challenge of real-time metrology for control of flexible and reconfigurable technological plasma systems. Plasma technologies not only underpin many high-end multi-billion pound manufacturing industries of today, but also are critical elements for the invention of new devices of the future. A new revolution is underway in plasma processing; the 'ivy-bridge' 3-dimensional atomic layer nano-structures of Intel Corp. and new carbon-based supermaterials of Element Six have only just been realised. This opens up new horizons for inventions.

Envisaged applications of next-generation plasma processing include manipulation of edge-bonds of single-layer graphene, low power biologically implanted chips as sensors or neuro-motive devices, innovative chemistry applications for biofuel synthesis and realisation of micro-batteries, flexible micro-electronics, fabrication of micro-electromechanical devices, as well as directly using plasmas for medicine, surgery and pharmacy.

Realisation of all these critically depends on the development of new adaptable plasma processing techniques. As the industry transforms itself this is an exciting time. One critical bottleneck is the lack of adaptable process control. We propose a novel non-invasive sensor and virtual metrology concept to monitor substrate relevant parameters to enable real-time plasma tuning. This has developed from our pioneering research on the topic and recent discoveries.

Our innovative sensor - pulse induced optical emission spectroscopy (PiOES) is analogous to laser induced fluorescence spectroscopy and will instead of a laser utilise a non-intrusive low voltage rapid nanosecond electronic pulse to generate similar excitation conditions in the plasma. Electron impact excitation will create transient excited states and through the subsequent optical fluorescence, and associated temporal fingerprint, distinct atoms and molecules can be identified. The power and sensitivity of the technique originates from exploiting both the energy dynamics as well as the population dynamics in the nonlinear plasma-surface interface (sheath) region. This will allow detection down to atomic layer defects within micron locality.

The aim of our research programme is to develop and demonstrate our metrology technique in three extreme working environments: low pressure anisotropic plasma etching, synthetic diamond manufacturing, and atmospheric plasmas for medicine and pharmacy. We will demonstrate this metrology technique in full fabrication reactors and environments. This project is a collaboration between world-leaders in the field: The University of York, The University of Bristol, Intel Corp., Element Six, Andor Technology, Quantemol, Smith and Nephew, Hiden Analytical and Oxford Instruments. An advisory board, including leading members from a diverse range of companies and academia, has been installed to ensure industrial relevance and uptake as the project progresses.

According to the PACEC report [1], the industry sectors of "Advanced Materials and Micro and Nanotechnologies" that we propose to engage with have the highest Gross Value Add, i.e. return on collaborative research investment (£15.41 returned/£1 invested) of any industry sector in the UK.
Our project on "novel metrology concepts for a new generation of plasma manufacturing" will allow real-time process control, by exploiting the dynamics of the substrate-plasma interface. Applications of this technique, once realised, will have significant impact in the EPSRC and Technology Strategy Board highlighted areas of advanced materials, nanotechnology, next generation healthcare, energy and environment. An external Advisory Board for this project, consisting of both academics and companies, will provide guidance and assistance in delivering the impact for this project, including management of flexible funds in the project for future UK academic and industrial collaborations.

The primary economic impact of our project is through direct interactions with our industrial project partners.
- Employing our new metrology techniques will allow Intel Corp. to achieve the continuing drive towards smaller feature sizes, lower power and faster processors. Element Six will be able to improve the quality and cost efficiency of their carbon super-materials, expanding their market.
- Emerging cold atmospheric-pressure plasma technologies, improved with our metrology techniques, are increasingly implemented in large-scale industrial processes and commercial products. Their applications include plasma catalysis for diverse environmental applications e.g. synthetic bio-fuel generation, and plasmas in healthcare and medicine, e.g. cancer treatment and precise single-cell surgery. We will work with Smith & Nephew on this topic.
- Wider uptake of our proposed metrology technology in the other plasma-manufacturing industries will be achieved by engaging with the UK systems integrator companies on our Advisory Board (Hiden Analytical and Oxford Instruments).

Society impact will mainly be through novel commercial products of existing and new start-up companies.
- Enabling the ongoing trend of smaller, faster and innovative (e.g. flexible) technology applications in everyday life.
- Improved quality of life for the ageing population in the UK and beyond through the direct use of plasma devices for medical procedures, but also the development of advanced biological sensors, neuro-robotics, and remote patient monitoring, thereby reducing the load on hospital beds.
- Environmental applications of cold atmospheric plasmas, will help society deal with current environmental issues like exhaust gas cleaning, alternative fuel generation, chemical and environment sensors.

Dissemination of outcomes of this project will include scientific and industrial conferences like the annual de Beers Diamond Conference, Intel European Conference and EPSRC Manufacturing Future Conference. The key result of this project will be the development of the concept of using the plasma itself as a sensor to monitor and control a plasma process. This will also impact other related highlighted areas with significant future application potential, e.g. plasma medicine, environmental applications and fusion energy. Flexible, impact acceleration funds in this project will be used to bring together UK academic and industrial beneficiaries in these fields and encourage further development of new collaborations, ideas and applications.

Finally, the project will train PDRAs and PhD students in the field of plasma manufacturing. Their experience of working with industrial plasma tools, as well as regular direct contact with a commercial environment will make them ideally suited for a future job in the UK plasma manufacturing industry.

[1] Technology Strategy Board, "Evaluation of the Collaborative Research and Development Programmes" compiled by PACEC Consultants, Sep 2011