Intercomparison of Measurement on Step Height Standards by SPM
Project Description
The comparison should support the MRA. The standards are similar to those of the NANO2, but with smaller lines of 3 µm, 6µm and 20 µm. Based on the properties of the SPM the 6 µm line will be used. Three standards with nominal step heights of 40 nm, 1000 nm and 2000 nm will be used. During the NANO2 preliminary inter-laboratory comparison on step height standards the PTB was ask to perform bilateral comparisons on step height for scanning probe microscopes. Therefore we plan to set up a new comparison for SPM in which the participating institutes should perform measurements on step height standards. The comparison should support the MRA. The standards used are similar to those of the NANO2, but with smaller lines of 3 µm, 6 µm, and 20 µm. The step height standards cover a range from 7 nm to 2400 nm.
The technical report will be sent to the participants in the next weeks. The comparison should start in Feb. 2004. Nevertheless, interested partners could inform the pilot lab by an e-mail in which they announce their interest to participate with their scanning probe microscope. Please, send information about the measurement range (x,y, z) and the measurement mode of the SPM, too. The project is in the feasibility stage. More details can be given in April 2003. The comparison could start in summer 2003. Possible partners have or will be informed by e-mail. Nevertheless, interested partners could inform the pilot lab. by an e-mail in which they announce their interest to participate with their scanning probe microscope. Please, send information about the measurement range (x,y,z) and the measurement mode of the SPM, too.
Final Report 2005-04-21
The step height standards used were similar to those of the NANO2, but compared to NANO2 the step height range measured was extended from 800 nm up to step heights of 2000 nm. Based on the scanning properties of the SPM a 6 μm line was used for the measurements on three standards with nominal step heights of 40 nm, 1000 nm and 2000 nm.
This comparison should support the MRA.
The participating laboratories provided a report with a short description of the measurement set-up and the conditions, the results of the measurement, and the combined standard uncertainty. Contributions to the uncertainty budgets depend on the method and the instrument used. For each standard a reference value was
calculated as the weighted mean of all measurements yi. The weights were u-2(yi). To set up the |En | £ 1 criterion, the expanded uncertainty U with a coverage factor of k = 2 was used. The results from IMGC for the SH1000 and SH2000 did not fulfil the En-criteria. All other values measured for each standard were used to calculate the reference value and its uncertainty.
The comparison was performed between a small number of participants and in a short time. Some delay occurred due to an unexpectedly long service time for one instrument. The results show that also step heights of more than 1 μm in height can be measured by using sophisticated canning probes microscopes with very small uncertainties.