Metrology for movement and positioning in six degrees of freedom

Electronics, aerospace, and automotive products worth billions of euros to the EU economy, all depend on precision engineering – an area where Europe has a world leading capability. As components shrink in size, maintaining this global standing requires increased measurement accuracy and improved quality control. Having confidence that machine tools working in 3D, or with six degrees of freedom (6DoF), are following precise pre-set movements to form components with micro-sized features is essential. Accelerating quality assessments based on measurements made by surface scanning probes, and more rapid confirmation that machine tools are reliably following pre-set specifications will increase precision engineering productivity and help European industries to remain competitive.

The EMRP project Metrology for movement and positioning in six degrees of freedom has increased the accuracy of determining machine tool or positioning stage micro-movements, and developed ways to increase the usability of rapid and extensive scanning probe microscopy measurements.

The project developed:

• A mobile, easy-to-use measurement system that can characterise the motion of precision machine tools by detecting changes to light interference patterns generated from nanoscale movements of the machine tool.
• A powerful semiconductor laser system suitable for providing multiple light beams for 3D dimension measurements, using interferometry. This has potential to be used for precise nanoscale measurements, where high laser output power and advanced frequency tuneability are required for industrial applications.
• A calibration measurement strategy for manufacturing or microscopy stages that make submicrometre movements. The strategy is based on performing numerous measurements along a single axis, and fewer measurements on other axes.
• Strategies to decrease the effects of tip wear and instrument drift during extended or rapid scanning of surface features using atomic force microscopy. A good practice guide has been issued to promote measurement comparability and reliability.

Traceable nanometre measurements of position, angle, and straightness are essential in many areas of industry and science. Examples include the highly precise positioning stages used in semiconductor manufacture by photolithography, and samples undergoing analysis using electron microscopy. As a result of this project, new calibration services have been introduced for instruments used to determine the position of machine tools that inspect nanoscale samples through to larger industrial parts. A 10-50 fold improvement in measurements for positioning accuracy in both small and large 3D systems with simultaneously large, linear, and angular motions has also been achieved. This will improve high-end manufacturing efficiency, raise quality, and reduce defects in cutting-edge products such as semiconductors and automotive parts, whilst also accelerating inspection. Improved efficiency in precision manufacturing and quality control across Europe is essential for securing technological leadership and sustainable economic growth.