Thickness measurement of substrate using color metrology

A computer program product for obtaining values representative of a plurality of thicknesses of a plurality of locations on a substrate, the computer program product tangibly embodied in a non-transitory computer readable medium, comprising instructions for causing a processor to:

• receive a color image of the substrate from a color camera;
• store a function that provides a value representative of a thickness as a function of a position on a predetermined path in a coordinate space of at least two dimensions including a first color channel and a second color channel;
• for each pixel of a plurality of pixels at different locations in the color image,
• determine a coordinate of the pixel in the coordinate space from color data in the color image for the pixel;
• determine a position of a point on the predetermined path that is closest to the coordinate of the pixel;
• and
• calculate a value representative of a thickness of a layer on the substrate from the function and the position of the point on the predetermined path, thus generating the values representative of the plurality of thicknesses thickness of the plurality of locations on a substrate.