A chip device for on-line assessment in nano-scale surface manufacture

Lead Research Organisation: University of Huddersfield
Department Name: Sch of Computing and Engineering

Abstract

In developed economies the manufacture of high added value critical components is rapidly shifting to the design and fabrication of micro and nano structured and freeform surfaces. The market for components possessing these surfaces is huge (the annual turnover is over 75 billion in the UK) and growing by 25% per year (1996-2005) with great investment in the UK, USA, Germany, France and East Asia. The rapidly increasing use of nano scale and ultra-precision structured surfaces is wide ranging and covers optics, hard disks, medical devices and the micro moulding industries that all critically rely on ultra precision surfaces. The scale of the products does not limit the need for the surface precision. The James Webb Space Telescope project for instance requires 1.3 metre size complex freeform surface segmented telescope mirrors with less than 10nm form deviation.Ultra-precision multi-axis machining and micro-fabrication technologies are enabling technologies that allow the designed surfaces to be fabricated with the required sub-micrometer form accuracy and nanometric surface topography. There is however a fundamental limiting factor to manufacture of such surfaces, namely the ability to measure product with high level accuracy, and also on-line.The proposed project attempts to create a novel in/on line surface measurement system, which integrates the essential optical components of an interferometer, such as, light source, optical components, a detector, into a solid state chip device. The key and novel aspect of the research, within the project, is to study and develop techniques to fabricate and integrate optical elements onto the same motherboard chip. The feasibility of building a robust and miniature surface measurement system and applying it to on-line micro and nanoscale surface measurement will then be explored. The proposed project will involve an interdisciplinary team of researchers and industrialists: the Surface Metrology Group at the University of Huddersfield (UoH), the Centre for Integrated Photonics (CIP), instrument manufacturer Taylor Hobson Limited (TH) and Ultra-Precision Surfaces at the OpTIC Technium (OpTIC) in North Wales. The group's combined activities include 'state of the art' capabilities in surface metrology, integrated optics, metrology instruments and ultra-precision surface manufacturing. The aim is to demonstrate a unique and novel technique for micro, nano scale manufacture that represents a step change in the field of surface metrology, integrated optics, nanotechnology, and instrumentation. The inclusion of the partners demonstrates the supply chain required in such systems / the research group (Huddersfield) developing the fundamental measurement system approach, a technology translator and device manufacturer (CIP), a measurement tool manufacturer (Taylor-Hobson) and an end user (OpTIC). Should the project succeed as planned, then there is an excellent chance of downstreaming this approach into commercialisation.CIP is a subcontractor on this project responsible for the delivery of the advanced optoelectronic devices used in the project and the final optoelectronic hybrid chip. CIP - a not for profit organisation - has a track record of working with university groups in this way for the development of advanced components for research. Previous examples being the EPSRC funded projects PRINCE and PORTRAIT where CIP were (and are) responsible for the development of leading edge research devices for telecommunications, terahertz imaging, biophotonics and sensing applications within these projects. The centre provides an open acess R&D facility for industry and universities. The EPSRC have agreed to support the access to CIP for academics by funding full economic costs on individual research grants.
 
Description This 3 year research project investigated an integrated-optic chip interferometer device for application in high/ultra precision surface metrology. The concept was to combine modern telecommunications and hybrid silicon photonics in order to develop a fully miniaturised measurement system that could usefully be employed for online surface metrology. The project served to address some of the timely metrology needs in high/ultra precision manufacture by expanding the gamut of online techniques available.

The project was carried out in collaboration with the Centre for Integrated-Photonics (CIP), a UK company who are world leaders in the design and development of silica-on-silicon hybrid photonic devices. In this type of manufacture, hybrid photonics structures such as light sources and photo-detectors are produced on daughter boards that are mounted on a single silica on silicon substrate (motherboard) containing waveguides enable light transfer. The integrated-chip device used the concept of wavelength scanning and a dispersive probe to effectively sweep a beam of light across a profile on a surface in the manner of a stylus, but without any destructive contact with the object to be measured. The analysis of the surface height variation was based upon phase shifting interferometry. The wavelength scanning was produced by an integrated tuneable laser module formed from an extended cavity laser diode. The tuning mechanism was provided by using a custom designed thin film filter, which passes a single cavity mode. The resonating mode (and thus wavelength) is changed by altering the angle of the filter using a pivot/sprung lever arm mechanism actuated by a miniature linear piezo motor. Other structures, necessary for operation as an interferometer, are an optical-coupler and photo-detector which were also integrated into the device, yielding a fully integrated measurement system. A remote optical probe, coupled to the chip interferometer by optical fibre, was designed to produce the beam scanning over the surface and re-couple the reflected light for analysis.

The optical interferometer was fibre coupled to an optical probe comprising of the diffraction grating and phase shifting mirror. Software and hardware was developed for data acquisition and control of the measurement system as well as analysis of the data. After assessments of various algorithms, the Carré method was implemented for calculating surface height because of its insensitivity to the phase shift interval. The final measurement device was contained within a package dimension of 100mm x 50mm x 20mm.

The results generated by this research work have produced six refereed journal papers and four refereed conference/seminar papers.
Exploitation Route The chip interferometer device resulting from the research has many potential applications where an instrument is required to have both small size, nanometre scale measurement resolution and a remote scan head which can mounted on a machining tool. Non-academic contexts are in industrial applications requiring on-line metrology for high/ultra-precision manufacture, high added value manufacture. These manufacturing requirements may be found in industrial fields such as aerospace, optics manufacture, biomedical and the energy sector, specifically internal confinement fusion research. The international patent associated with this research will lead to the technology being released to industry, with IP licensing as a potential pathway. Follow on research funding has been acquired to study and optimise and develop the concept further. Further research into the developed concepts form part of ERC Project ERC-AdG-228117 (1.9 million euro). The technology also forms a core part of research Theme II: Underlying techniques for "factory on the machine" in the EPSRC Centre for Innovative Manufacturing in Advanced Metrology (9 million GBP).
Sectors Manufacturing/ including Industrial Biotechology

 
Description A Novel Chip Device for on-line micro/nano-scale surface measurement was developed for this project.
First Year Of Impact 2010
Sector Manufacturing, including Industrial Biotechology
Impact Types Economic

 
Description Optropreneurs Limited, OpTIC 
Organisation OpTIC Glyndwr Ltd
Country United Kingdom 
Sector Private 
Start Year 2007
 
Description Rank Taylor Hobson Ltd 
Organisation Rank Taylor Hobson Ltd
Country United Kingdom 
Sector Private 
Start Year 2007
 
Description Poster Presentation - EPSRC Theme Day in Manufacturing Research 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The EPSRC Theme Day in Manufacturing Research took place in London on Thursday 15 April 2010. As a review of this important topic is timely given the current economic climate and focus on a more resilient economy, EPSRC was interested in assessing a representative sample of funded research projects relevant to Manufacturing research by an independent panel of international and industrial experts.
Year(s) Of Engagement Activity 2012