System for sensing a sample

Abstract

A profiler or scanning probe microscope may be scanned across a sample surface with a distance between them controlled to allow the sensing tip to contact the surface intermittently in order to find and measure features of interest. The distance is controlled so that when the sensing tip is raised or lowered to touch the sample surface, there is no lateral relative motion between the tip and the sample. This prevents tip damage. 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. A quick step mode may also be performed by choosing steps of lateral relative motion to be smaller than 100 nanometers to reduce probability of tip damage. In this mode, after each vertical step to increase the separation between the tip and the sample, it is detected as to whether the tip and the sample are in contact. If they are still in contact after the vertical step, one or more vertical steps are taken to increase the separation, and no vertical step to reduce the separation is taken and no lateral relative motion is caused until it is determined that the tip and the sample are no longer in contact.

1 - 82 . (canceled)  
     
     
         83 . A method apparatus for sensing a high aspect ratio feature on a surface of a sample, employing a sensor assembly comprising a probe and at least a first and a second sensing tips on the common probe with known spatial relationship to each other, comprising: 
 causing the first sensing tip to scan across the surface with the first tip in contact with the surface until the feature is found; and    scanning the second sensing tip across the surface with the second tip in intermittent contact with the surface to measure the feature.    
     
     
         84 . The method of  claim 83 , the second sensing tip comprising a nanotube; wherein said scanning scans the surface so that the tip of the nanotube is in intermittent contact with the surface to measure the feature.  
     
     
         85 . The method of  claim 84 , said nanotube extending beyond the first sensing tip, so that during the scan of the first sensing tip across the surface, the nanotube is buckled.  
     
     
         86 . A method for sensing a high aspect ratio feature on a surface of a sample employing a sensing tip of a profiler or scanning probe microscope, said method comprising the steps of: 
 providing height information of the surface within a target area of the surface;    positioning the tip above one location of the surface in the target area;    scanning the sensing tip across the surface; and    controlling a distance between the surface and the tip using said information during the scanning so that the tip contacts the surface intermittently and so that the tip does not contact the surface laterally when the tip is scanned across the surface; wherein said controlling controls said distance so that the tip is scanned without substantially moving the tip and the surface laterally relative to each other when the tip and surface are in contact, wherein the tip does not penetrate said feature when scanning across the surface.    
     
     
         87 . A method for sensing a surface of a sample employing a probe with a sensing tip, said method comprising the steps of: 
 (a) positioning the sensing tip above one location of the surface of the sample;    (b) reducing a distance between the surface and a sensing tip without substantially moving the tip and the surface laterally relative to each other until the tip touches the surface;    (c) measuring data related to a height of the sample surface with the tip in contact with the sample at a contact point;    (d) increasing a distance between the tip and the contact point of the surface without substantially moving the tip and the surface laterally relative to each other until such distance is substantially equal to a predetermined value;    (e) causing lateral relative motion between the sensing tip and the surface and positioning the tip so that the tip is above a location adjacent to and spaced apart from said one location; and    (f) repeating steps (b) through (e) at a plurality of locations of the surface to obtain an image of the surface; wherein said lateral relative motion in step (e) is over a lateral distance less than about 100 nm.    
     
     
         88 . The method of  claim 87 , wherein step (a) positions the sensing tip without adequate prior information concerning extent of height variations of the surface to avoid lateral contact between the tip and the surface when the tip is scanned across the surface.