Micro and Nano Technology (MNT) Measurement Club. 1-day meeting. Thin Films and Coatings

Transcription

1 Micro and Nano Technology (MNT) Measurement Club 1-day meeting Thin Films and Coatings Venue: National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW Date: Wednesday 5 July 2006 Overview of Meeting The aim of this meeting is to raise awareness of and discuss the measurement and characterisation needs, requirements and issues in thin film deposition and coating technologies. It will include presentations on new coating methods, including the application of nanofabrication techniques, and on current metrology research within the DTI s National Measurement System (NMS). Areas where there are outstanding measurement issues and needs, not fully addressed by existing measurement techniques, will be highlighted. This meeting will be of interest to researchers, engineers, scientists and technical/quality control managers in R&D and manufacturing organisations who would like to find out more about measurement and characterisation issues, techniques, tools and facilities in order to improve their products and processes and to network with others working in this field REGISTRATION, COFFEE PROGRAMME Introduction to meeting - Chairman :00 Pulsed plasma polymerisation for water and oil repellency Dr Stephen Coulsen, P2i Characterisation of large area optical coatings on glass Paul Warren, Pilkington Thin film extraction from scanning white light interferometry Daniel Mansfield, Taylor-Hobson COFFEE Nanofabrication of fibres, fabrics, coatings and membranes Prof. George Stylios, Heriot-Watt University The structure and mechanics of ultrathin multi-layered coatings Dr David Mendels, National Physical Laboratory LUNCH Scanning probe energy loss spectroscopy Adriano Pulisciano, University of Birmingham

2 Super smooth optical coatings by closed field magnetron sputtering Michael Walls, Applied Multilayers Measurement of surface and coatings mechanical properties Dr Nigel Jennett, National Physical Laboratory MEETING CLOSE PRESENTATION ABSTRACTS AND PRESENTER BIOGRAPIES Title: Pulsed Plasma Polymerization for Water and Oil Repellency Presenter: Dr Stephen Coulsen P2i Stephen developed the P2i technology whilst carrying out his PhD at Durham University on Liquid repellent surfaces using plasmas and was employed by the MoD to set up a plasma capability and further scale-up the patented technology for industrial applications. In 2001 Stephen moved into project managing the UK Nuclear Biological and Chemical clothing programme, but continued to exploit the plasma technology for a range of commercial applications. Stephen was the founding member of P2i when it was formed in February 2004 and has 10 years experience in plasma processing. Title: Characterisation of large-area optical coatings on glass Presenter: Paul Warren Pilkington A variety of coatings are deposited on glass for energy-efficiency in the building and transportation markets. Some of these coatings have relatively poor resistance to mechanical damage. Although this damage does not significantly affect the thermal performance of the window, the damage can be visible to the naked eye. In this presentation, we discuss some of the methods used to characterise the mechanical properties of the coatings, especially the task of measuring the residual stresses present in multi-layered systems where each layer may only be ~10nm thick. Paul Warren has worked at the Pilkington Technical Centre, Lancashire, for nearly 9 years, leading the Materials Group - measuring the bulk properties of glasses, and the mechanical properties of coatings. Prior to this, he worked in various universities (Oxford, Santa Barbara - USA, Leeds) on a variety of topics including the relationship between the electrical and mechanical properties of gallium arsenide, the brittle-ductile transition in silicon and sapphire, and interfacial properties in metal-matrix composites. Title: Thin Film Extraction from Scanning White Light Interferometry

3 Presenter: Daniel Mansfield Taylor-Hobson Scanning white light interferometry (SWLI) is now an established technique for the measurement of surface topography. It has the capability of combining sub-nanometre interferometric resolution with a range limited only by the z-traverse, typically at least 100µm. A very useful extension to its capability is the ability to measure thin films on a local scale. For films with thicknesses in excess of ~2µm (depending on refractive index), the SWLI interaction with the film leads simply the formation of two localised fringe bunches, each corresponding to a surface interface. It is evidently relatively trivial to locate the positions of these two envelope maxima and therefore determine the film thickness, assuming the refractive index is known. For thin films (with thicknesses ~20nm to ~2µm, again depending on the index), the SWLI interaction leads to the formation of a single interference maxima. In this context, it is appropriate to describe the thin film structure in terms of optical admittances; it is this regime that is addressed through the introduction of a new function, the 'helical conjugate field' (HCF) function. This function may be considered as providing a 'signature' of the multilayer measured so that through optimization, the thin film multilayer may be determined on a local scale. Following the derivation of the HCF function, examples of extracted multilayer structures are presented. This is followed by a discussion of the limits of the approach. Biography Since graduating in physics from Stirling University in 1974, I spent my first 4 years working in thin films at Barr and Stroud (Glasgow). In 1978 I moved to STC (Harlow) to work as a thin film physicist specialising in the infra-red and in CO 2 laser components. In 1982 I joined Taylor Hobson and am now employed as the company physicist. My work has been metrology-driven and has covered such areas as ultra-sonics, thermal imaging, physical optics and simulation. My main contribution (together with Ian Buehring) has been the PGI gauge. I am currently working on information-extraction from SWLI. Title: Nanofabrication of fibres, fabrics, coatings and membranes Presenter: Prof. George Stylios Heriot-Watt University.. Title: Structure and mechanics of ultrathin multi-layered coatings Presenter: Dr David Mendels National Physical Laboratory This presentation will discuss novel measurement methods and design tools for multi-layered engineering coatings. Multi-layered coatings are increasingly used in a wide range of industrial applications, mainly for protection (against wear, indentation, erosion, or as thermal barriers) or for optical performance including decorative purposes. Applications are mainly found in the transport industries (automotive and aerospace), in the tooling as well as in the optics industry. Other applications include epitaxial layers on semi-conductors, key to the electronic industry. Our recent activities have led to a comprehensive integration of several measurement techniques: - preparation and TEM observation of cross-sections of coatings, including the observation of deformation mechanisms under a nano-indenter; - novel structural test methods, such as the micro-four point bending test - low load scratch test to determine the energy release rate of debonding interfaces.

4 These measurement techniques have been coupled with analytical and finite element models, with particular emphasis on the intrinsic mechanical properties of the constituents, and their internal stress state. David Mendels took his PhD in Switzerland, at the polytechnic school of Lausanne, where he studied the influence of interfacial stresses on viscoleastic properties of polymers. During that period, he was also teaching polymer physics and non-contact strain measurement methods. Since 2001, he has initiated and developed the area of structural nano-mechanical measurement methods at NPL. While his main interest remains polymer physics and nano-scale interactions, he has also been continuously involved in various advanced materials activities: nano-structured multi-layered coatings, piezoelectric ceramics and thin films, scanning probe techniques. He is currently co-chairing the VAMAS pre-standardisation committee on nano-materials testing. Title: Scanning Probe Energy Loss Spectroscopy Presenter: Adriano Pulisciano Birmingham University Title: Super smooth optical coating by closed field magnetron sputtering Presenter: Michael Walls Applied Multilayers Title: Measurement of surface and coatings mechanical properties Presenter: Dr Nigel Jennett National Physical Laboratory The determination of the mechanical properties of surfaces and coatings is vital for developing a functional understanding and ultimately providing quality assurance in a wide range of surface treatments and nanotechnologies. Instrumented (Nano)indentation is a rapidly maturing method for the determination of the elastic and plastic properties of small volumes of materials, e.g. thin films and nano-structures. Standardisation assures reproducibility of the test result for users and is essential to the development of world trade. BS EN ISO 14577:2002 parts 1-3 covers tests on bulk materials and Part 4 is being drafted to cover the determination of coating properties by indentation normal to the coating surface, even when the indentation response includes a significant component due to the substrate. This talk describes an adaptive protocol (the basis of ISO/DIS 14577:Part 4) for the robust estimation of hardness and indentation plane strain modulus of both brittle/hard (e.g. Alumina or DLC coatings) and ductile/soft (e.g. Gold and Aluminium) coatings on hard and soft substrates. The method for modulus determination is validated by comparison with independent techniques such as impact resonance and the frequency dispersion of surface acoustic waves. By combining

5 indentation with these acoustical techniques, a consistent set of values for modulus, Poisson s ratio, density and thickness can be determined for a coating. The entire set of results can be validated by direct measurement of either coating thickness or density. Conversely, this allows the non-destructive measurement of film thickness or density with a precision of ~ 1%, - for thickness this is an uncertainty comparable to high resolution SEM of a cross-section. Finally instrumented indentation has shown that there is a clearly measurable change in the yield point of materials as a function of length scale. Thin coatings are harder than bulk materials. This has length-scale implications for the development of protocols to obtain tensile properties of materials by instrumented indentation, but opens up the possibility of design rules for length-scale manipulation of material properties, e.g. increasing yield stress without reduction in ductility. Nigel has 20 years experience of the fabrication and characterisation of nano-structured materials and has worked at NPL for over 14 years developing nano-mechanical test methods. After 6 years researching magnetic multilayers at Bristol University (1990 PhD, 1991 Chartered Physicist), Nigel moved to NPL in 1992 to work on developing traceable SPM and nano-mechanical measurements of surfaces and coatings. In 1998 he created a research group focussed on surfaces, coatings and nano-mechanics and is a seasoned leader of projects funded by Government, Industry and the European Commission. Nigel is Convenor (Chairman) of the ISO working group drafting the standard for instrumented indentation of coatings and international chairman of the VAMAS technical working area on mechanical properties measurement of thin films and coatings (TWA22). He is currently Guest Editor of a Special Instrumented Indentation Issue of Philosophical Magazine.