Metrology robustness based on through-wavelength similarity

A computer program product comprising a non-transitory computer readable medium having instructions therein, the instructions, upon execution by a computer system, configured to cause the computer system to at least:

• obtain a measurement result from a target on a substrate, by use of substrate measurement recipe;
• determine a parameter value from the measurement result, wherein the parameter characterizes dependence of the measurement result on an optical path length of the target for incident radiation used in accordance with the substrate measurement recipe to obtain the measurement result;
• and
• based on the parameter value, adjust a substrate measurement recipe.

A method comprising:

• obtaining a measurement result from a target on a substrate, by use of a substrate measurement recipe;
• determining, by a hardware computer system, a parameter value from the measurement result, wherein the parameter characterizes dependence of the measurement result on an optical path length of the target for incident radiation used in accordance with the substrate measurement recipe to obtain the measurement result;
• and
• based on the parameter value, adjusting a substrate measurement recipe.