Nanoscale surface mapping
Challenge
Advanced manufacturers of nanotechnologies, semiconductors and solar cells are increasingly innovating with multifunctional materials and this requires the accurate characterisation of very small features. Atomic Force Microscopy (AFM) allows very precise sub-nanometre measurements of surface features and could in the future provide manufacturers with the highest accuracy levels for production process quality assurance (QA).
AFM probe tips scan the surface of materials measuring atomic scale interactions and this information can be used to construct 3D images of surface features, as well as for characterising the materials electrical properties. Current AFM topography scans creating maps of surface features are time consuming. Taking large numbers of measurements at regular intervals across a material’s surface generates huge amounts of data for processing and the length of time needed creates problems. AFM tips experience wear and slight operating temperature changes can lead to minor drifts over time, both of which compromise measurement accuracy. Overcoming these accuracy limitations is essential to enable greater uptake of AFM as a quality assessment tool.
Solution
The EMRP project, Metrology for movement and positioning in six degrees of freedom, developed a new adaptive scanning approach for AFM measurements, allowing users to concentrate measurements on areas of interest, and reducing the number of data points accumulated over a measurement scan. This helps minimise tip wear and speeds scans so reducing the likelihood of temperature drift. The project also investigated factors affecting AFM performance and developed an improved statistical model for determining measurement uncertainties and minimising measurement errors. This knowledge has been incorporated into freely available software (Gwyddion), which enables AFM users to preselect the instrument’s measurement pattern removing reliance on conventional equi-spaced data points. The new software, backed by an open data library of test parameters provides optimised AFM scanning, reducing tip wear and measurement time.
Impact
NenoVision s.r.o, a Brno University of Technology spinout, markets the Litescope, an AFM accessory for scanning electron microscopes aimed at researchers in the materials science, nanotechnology, semiconductor and solar cell markets worldwide. The Litescope extends the capabilities of electron microscopy machines used for surface imaging to the analysis of a material’s mechanical, electrical and magnetic properties. NenoVision were one of the first to incorporate the project’s AFM software into its product. Using the free release software saved them the time, money and risk of developing a similar software themselves.
For routine industrial measurements, such as in quality assurance, it is not necessary to measure entire surfaces, just specific features. The Litescope, with project software, now brings adaptive AFM scanning to the market, reducing the number of measurements and time needed to analyse samples. This speeds processing time whilst mitigating the problems of AFM tip wear and drift.
More flexibility and faster scans allow AFM measurements to be applied to a wider range of nanoscale research applications, and opens its use for more routine manufacturing measurements such as QA. This could save time and money in R&D and create a highly accurate measurement tool for innovative nanoscale technologies, improving product quality and reducing waste.
- Category
- Industry,
- EMRP,