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Tip characterization method using multi-feature characterizer for CD-AFM



Ndubuisi G. Orji, Hiroshi Itoh, Chumei Wang, Ronald G. Dixson, Sebastian Schmidt, Bernd Irmer, Peter S. Walecki


In atomic force microscopy (AFM) metrology, the tip is a key source of uncertainty. Images taken with an AFM show a change in feature width and shape that depends on tip geometry. This geometric distortion is more pronounced when measuring features with high aspect ratios, and makes it difficult to obtain absolute dimensions. In order to accurately measure nanoscale features using an AFM, the tip dimensions should be known with a high degree of precision. We evaluate a new AFM tip characterizer, and apply it to critical dimension AFM (CD-AFM) tips used for high aspect ratio features. The characterizer is made up of comb-shaped lines and spaces, and includes a series of gratings that may be used as an integrated nanoscale length reference. We also demonstrate a simulation method that could be used to determine and specify what range of tips sizes and shapes the characterizer can measure. Our experiments show that for non-reentrant features, the results obtained with this characterizer are consistent to 0.5 nm with the results obtained by using the widely accepted but slower methods that are common practice in CD-AFM metrology. A validation of the integrated length standard using displacement interferometry indicates a uniformity of better than 0.75%, suggesting that the sample could be used as highly accurate and SI traceable lateral scale for the whole evaluation process.


critical dimension AFM, tip characterizer, tip dilation


Orji, N. , Itoh, H. , , C. , Dixson, R. , Schmidt, S. , Irmer, B. and Walecki, P. (2015), Tip characterization method using multi-feature characterizer for CD-AFM, Ultramicroscopy, [online], (Accessed June 21, 2024)


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Created December 23, 2015, Updated November 10, 2018