Method and a system for combined characterisation of structures etched in a substrate

A method for characterising structures etched in a substrate comprising, for at least one structure etched in said substrate:

• an imaging step comprising the following steps:
• capturing, with an imaging device positioned on a top surface of said substrate, at least one image of the top surface of said substrate;
• and
• measuring a first data relating to said at least one structure from at least one captured image;
• an interferometric measurement step, carried out with a low-coherence interferometer positioned on said top surface, for measuring with a measurement beam positioned on said at least one structure, at least one depth data relating to a depth of said at least one structure;
• and
• a first adjusting step for adjusting said measurement beam according to said first data,
• said imaging step and said interferometric measurement step being carried out sequentially so that:
• the first data is measured during the imaging step,
• then the measurement beam is adjusted according to said first data, and
• then the interferometric measurement step is carried out with the adjusted measurement beam.