Pixel classification of film non-uniformity based on processing of substrate images

A method of classification of a film non-uniformity on a substrate, comprising:

• obtaining a color image of a substrate, the color image comprising a plurality of color channels;
• obtaining a standard color for the color image of the substrate;
• for each respective pixel along a path in the color image, determining a difference vector between the a color of the respective pixel and the standard color to generate a sequence of difference vectors;
• and
• sorting the pixels along the path into a plurality of regions including at least one normal region and at least one abnormal region based on the sequence of difference vectors, including comparing a multiplicity of the difference vectors in the sequence to a threshold.

A polishing system, comprising:

• a polisher to polish a substrate;
• an in-line metrology system to obtain to color image of a substrate, the color image comprising a plurality of color channels;
• and
• a controller configured to
• receive obtain the color image from the in-line metrology system,
• obtaining a standard color for the color image of the substrate,
• for each respective pixel along a path in the color image, determine a difference vector between the a color of the respective pixel and the standard color to generate a sequence of difference vectors,
• classify the pixels along the path as normal or abnormal based on the sequence of difference vectors by comparing a multiplicity of the difference vectors in the sequence to a threshold,
• sort the pixels into one or more regions in response to the pixels being identified as normal or abnormal, and
• adjust a polishing parameter of the polisher for a region having pixels identified as abnormal.