International intercomparison of scanning tunneling microscopy

Abstract

Because scanning probe microscopes produce three-dimensional data of almost any solid they have a strong potential as metrological tools. Results are presented from the first international intercomparison between four national metrology laboratories. On three-dimensional calibration standards the mean deviations between instruments were typically Ͻ2% in the x direction, Ͻ5% in the y direction, and Ͻ10% in the z direction. Eight samples were circulated for roughness measurements and 19 roughness parameters were calculated for each image. In the range where the scanning probe microscope measurements overlapped with classical techniques ͑profilometers͒ the agreement was good. Also a gauge block of hardened steel ͑Ϸ900 HV͒ with an array of Vickers indentations having diagonal lengths ranging from 3 to 60 m was circulated and measured.

Nanoscale roughness and bias in step height measurements by atomic force microscopy

“…The roughness is now reduced by the increasing probe width by up to 1/3 from the value for the continuum surface. This effect is meaningful, being greater than the typical working calibration error of such systems as indicated in the international comparison of 1996 [48]. The increase in the mean height is important and must be considered when measuring step heights for overlayers and substrates of differing roughnesses or for measuring crater depths where the crater floor is rougher than the original surface.…”