SYSTEM FOR SENSING A SAMPLE

摘要

A prolifer (60) or a scanning probe microscope may be scanned across a sample surface (40) with a distance between them controlled to allow the sensing tip (20) to contact the surface intermittently in order to find and measure features of interest. The distance is controlled so that when the sensing tip (20) is raised or lowered to touch the sample surface (40), there is no lateral relative motion between the tip and the sample. Prior knowledge of the height distribution of the sample surface may be provided or measured and used for positioning the sensing tip initially or in controlling the separation to avoid lateral contact between the tip and the sample. The process may also be performed in two parts: a fast find mode to find the features and a subsequent measurement mode to measure the features.