Methods and systems for obtaining a 3d profile of a sample

A method for obtaining a 3D profile of a sample, the method comprising:

• receiving a first set of data provided by a first metrology tool and relating to a first group of structural parameters of the sample, the first set of data comprising a first set of measured signals and a first set of operational parameters;
• receiving a second set of data provided by a second metrology tool and relating to a second group of structural parameters of the sample, the second set of data comprising a second set of measured signals and a second set of operational parameters, wherein the first and second groups comprise at least one structural parameter in common;
• performing a first analysis, the first analysis comprising analyzing the first set of data to obtain values for the first group of structural parameters;
• performing a second analysis, the second analysis comprising analyzing the second set of data to obtain values for the second group of structural parameters, wherein values obtained in the first analysis for at least some of the common structural parameters are used to constrain the second analysis;
• and
• generating a substantially complete 3D structural profile of the sample based on combining the values obtained in the first and second analyses.