The new European ELENA project, which aims to advance “Electrical nanoscale metrology in industry”, started on 1st September 2021
Micro- and nano-electronics are considered by the European Commission (EC) a Key Enabling Technology (KET) with high potential for innovation throughout the economy, currently accounting for 10 % of EU Gross domestic product (GDP), and fostering highly skilled employment. A competitive advantage in the semiconductor industry is gained through the exploitation of new materials and processes, translating into improved component performance. This requires a metrological infrastructure allowing reliable nanoscale characterisation of new materials and devices, particularly in terms of their electrical parameters and properties. The development of electrical nanoscale metrology has also been clearly identified in the Nano‑electronics Standardisation Roadmap by the International Electrotechnical Committee (IEC-TC113).
The main metrological problem is the traceability and reliability of measurements of electrical properties at the nanoscale using conductive atomic force microscopes (C‑AFM) and scanning microwave microscopes (SMM). As scanning probe microscopy methods, C‑AFM and SMM are particularly attractive for use in the characterisation of electrical properties at the nanoscale because they allow non‑destructive analysis of electrical components. However, currently most measurements are taken with different instruments or using different reference standards and cannot be compared to each other nor used for modelling. This problem is compounded by a lack of established measurement protocols and a lack of easy to use reference standards. Furthermore, end users need best practice guides, worked examples, and access to easy to use 3D models to assess the influence of environmental conditions, the influence of the particular instruments used in the measurement, and the type of standards used. With these influencing factors, a simplified uncertainty budget can be established for the setup used for the measurement, which is a requirement in many quality standards. Additionally, to make measurements economically viable end users also require cost effective instrumentation, particularly for high frequency measurements.
The overall objective of the project is to establish a European metrological infrastructure and cost-effective technologies for C‑AFM and SMM to allow industry to conduct traceable measurements of electrical properties on materials and devices at the nanoscale. The specific objectives are:
- To develop and validate devices (DC to GHz reference standards with target uncertainties in the order of 10 % or less, probes, measurement microwave electronics), and procedures (broadband impedance matching) for GHz near field SMM. These developments should be suitable for DC-current measurements, high frequency (from 100 MHz to 50 GHz), material characterisation and impedance measurements involving C‑AFM and SMM techniques.
- To use the devices and procedures from objective 1 to develop calibration methods for C‑AFM and SMM techniques. This should include the quantification of uncertainty contributions due to influencing factors such as those that arise from the standards, from tip-sample interactions and those resulting from the measurement instrument itself in the laboratory environment.
- To develop reliable 3D multi-physics modelling based on analytical or numerical approaches, in order to evaluate the effect of the water meniscus, at the tip-sample interface, on the electrical measurement. This should also include an investigation of the effects of the tip’s real shape and composition, and of the tip-sample electromagnetic interactions, on the electrical measurement. The modelling data will be compared to the experimental data from objective 2.
- To establish simplified uncertainty budgets for the C‑AFM and SMM techniques using the results from objectives 2 and 3. In addition, to develop calibration methods for the key electrical measurands, including DC current from fA to μA, DC resistance from 100 Ω to 100 TΩ and HF admittance from 100 nS to 100 mS, for use in industrial applications. To develop ‘out of the lab’ electrical standards, such as calibration kits based on micro-size capacitors, for the industrial calibration of C‑AFM or SMM.
- To facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain in the micro- and nano-electronics sector (European industry, electrical SPM producers), standardisation organisations (IEC) and end users (NMIs and DIs, and academic and industrial R&D labs).
The project started on 1st September 2021 and will run for three years. It is led by LNE and involves 14 partners. The project has received funding from the EMPIR programme co-financed by the Participating States and from the European Union’s Horizon 2020 research and innovation programme.
Written by François Piquemal / Georges Favre