Linewidth calibration using a metrological atomic force microscope with a tip-tilting mechanism

摘要： The linewidth or critical dimension (CD) of a nanoscale line pattern is calibrated using a metrological atomic force microscope with a tip-tilting mechanism (tilting-mAFM). The tilting tip allows scanning of the line pattern’s vertical sidewalls. The tilting-mAFM performs two measurements on each side of the line pattern, and two datasets are stitched together to reconstruct the complete shape of the line pattern. Further, CD is measured based on this pattern. A linewidth standard with a subnanometer-scale uncertainty was used as a target sample to verify this CD calibration procedure. The calibrated CD using tilting-mAFM was 111.2 nm with an expanded uncertainty of 1.0 nm, which was the smallest uncertainty that was observed among the CD measurements that were reported using the tilting-AFM instruments. Further, the difference of this CD value from the reference CD was only 0.2 nm. The results reveal that tilting-mAFM can be used for CD metrology with a single-nanometer accuracy.