Variable Density Scanning

Abstract

Systems and techniques for varying a scan rate in a measurement instrument. The techniques may be used in scanning probe instruments, including atomic force microscopes (AFMs) and other scanning probe microscopes, as well as profilometers and confocal optical microscopes. This allows the selective imaging of particular regions of a sample surface for accurate measurement of critical dimensions within a relatively small data acquisition time.

1 . A method of controlling a cantilever based scanning instrument that determines information about a surface, comprising:
 using the cantilever to characterize and measure information from the surface by driving the cantilever to obtain more data density in a first region of the surface that is scanned by the cantilever, and to obtain less data density in a second region of the surface, where said information about said first and second regions of the surface are obtained from a single scan of the cantilever, and said single scan of the cantilever obtains more data density for said first region and less data density for said second region;   to obtain sampled information about the surface which has more data density in said first region and less data density in said second region from said single scan; and   producing an output showing said sampled information, where said output provides said more data density in said first region and said less data density in said second region.   
     
     
         2 . The method as in  claim 1 , wherein said output is a display output that shows more detail in one area of the surface for a single display obtained over a single scan. 
     
     
         3 . The method as in  claim 2 , wherein said display output that shows rectangular pixels that have one of each pixel being longer than an other side of said pixel, in said one area of the surface. 
     
     
         4 . The method as in  claim 2 , wherein said display output shows pixels which have a different size in said one area of the surface than in other areas of the surface. 
     
     
         5 . The method as in  claim 1 , wherein said cantilever scans in a first direction at said first and second scanning speeds over said single scan, where said first scanning speed is configured to obtain first data at a first data density in a first region of the sample and said second scanning speed configured to obtain second data at a second data density less than the first data density in a second region of the sample. 
     
     
         6 . The method as in  claim 1 , wherein said cantilever scans in a first direction and also in a second direction orthogonal to the first direction, at first and second scanning speed, where said first scanning speed is configured to obtain first data at a first data density in a first region of the sample and said second scanning speed configured to obtain second data at a second data density less than the first data density in a second region of the sample over said single scan. 
     
     
         7 . The method as in  claim 1 , further comprising creating a scan waveform used for said driving, and said scan waveform being configured to obtain higher density in said first region by scanning slower in said first region along each scan of said driving. 
     
     
         8 . The method as in  claim 7 , wherein said scan waveform includes first and second linear scan segments, and transition regions between said linear scan segments. 
     
     
         9 . The method of  claim 1 , wherein the cantilever based scanning instrument is an atomic force microscope. 
     
     
         10 . A cantilever based scanning instrument that determines information about a surface, comprising:
 a cantilever;   
       a controller that controls scanning of the cantilever, driving the cantilever to characterize and measure information from the surface by driving the cantilever to obtain more data density in a first region of the surface that is scanned by the cantilever, and to obtain less data density in a second region of the surface, where said controller drives said cantilever over a single scan to obtain data about said first and second region of the surface from said single scan of the cantilever, and said single scan of the cantilever obtains more data density for said first region and less data density for said second region during said single scan of the cantilever;
 said controller obtaining sampled information about the surface which has more data density in said first region and less data density in said second region in said single scan; and 
 said controller producing an output showing said sampled information, where said output provides said more data density in said first region and said less data density in said second region. 
 
     
     
         11 . The instrument as in  claim 10 , wherein said output is a display output that shows more detail in one area of the surface for a single display obtained over a single scan. 
     
     
         12 . The instrument as in  claim 11 , wherein said display output that shows rectangular pixels that have one of each pixel being longer than an other side of said pixel in said one area of the surface. 
     
     
         13 . The instrument as in  claim 11 , wherein said display output shows pixels which have a different size in said one area of the surface than in other areas of the surface. 
     
     
         14 . The instrument as in  claim 10 , wherein said controller causes said cantilever to scan in a first direction at said first and second scanning speeds during said single scan, where said first scanning speed is configured to obtain first data at a first data density in a first region of the sample and said second scanning speed configured to obtain second data at a second data density less than the first data density in a second region of the sample. 
     
     
         15 . The instrument as in  claim 10 , wherein said controller causes said cantilever to scan in a first direction and also in a second direction orthogonal to the first direction, at first and second scanning speeds over said single scan, where said first scanning speed is configured to obtain first data at a first data density in a first region of the sample and said second scanning speed configured to obtain second data at a second data density less than the first data density in a second region of the sample. 
     
     
         16 . The instrument as in  claim 10 , wherein said controller creates a scan waveform used for said driving, and said scan waveform being configured to obtain higher density in said first region by scanning slower in said first region along each scan of said driving. 
     
     
         17 . The instrument as in  claim 16 , wherein said scan waveform includes first and second linear scan segments, and transition regions between said linear scan segments. 
     
     
         18 . The instrument of  claim 10 , wherein the cantilever based scanning instrument is an atomic force microscope. 
     
     
         19 . An article comprising a non-transitory machine-readable medium embodying information indicative of instructions that when performed by one or more machines result in computer implemented operations comprising:
 using a cantilever to characterize and measure information from a surface being measured by driving the cantilever to obtain more data density in a first region of the surface that is scanned by the cantilever, and to obtain less data density in a second region of the surface, where said information about said first and second region of the surface are obtained from a single scan of the cantilever, and said single scan of the cantilever obtains more data density for said first region and less data density for said second region over said single scan;   to obtain sampled information about the surface which has more data density in said first region and less data density in said second region from said single scan; and   producing an output showing said sampled information, where said output provides said more data density in said first region and said less data density in said second region.   
     
     
         20 . The article as in  claim 19 , wherein said output is a display output that shows more detail in one area of the surface for a single display obtained over a single scan. 
     
     
         21 . The article as in  claim 20 , wherein said display output that shows rectangular pixels that have one of each pixel being longer than an other side of said pixel in said one area of the surface. 
     
     
         22 . The article as in  claim 20 , wherein said display output shows pixels which have a different size in said one area of the surface than in other areas of the surface. 
     
     
         23 . The article as in  claim 19 , wherein said cantilever scans in a first direction at said first and second scanning speeds during said single scan, where said first scanning speed is configured to obtain first data at a first data density in a first region of the sample and said second scanning speed configured to obtain second data at a second data density less than the first data density in a second region of the sample. 
     
     
         24 . The article as in  claim 19 , wherein said cantilever scans in a first direction and also in a second direction orthogonal to the first direction, at first and second scanning speed, where said first scanning speed is configured to obtain first data at a first data density in a first region of the sample and said second scanning speed configured to obtain second data at a second data density less than the first data density in a second region of the sample. 
     
     
         25 . The article as in  claim 19 , further comprising creating a scan waveform used for said driving, and said scan waveform being configured to obtain higher density in said first region by scanning slower in said first region along each scan of said driving. 
     
     
         26 . The article as in  claim 25 , wherein said scan waveform includes first and second linear scan segments, and transition regions between said linear scan segments. 
     
     
         27 . The article of  claim 19 , wherein the cantilever based scanning instrument is an atomic force microscope.