Multi-channel overlay metrology

An overlay metrology system configured to generate an image of at least one first structure buried in an object under test, the overlay metrology system comprising:

• a multi-channel energy unit configured:
• to selectively operate in a first mode to generate first photons having a first wavelength;
• selectively operate in a second mode to generate second photons having a second wavelength different from the first wavelength;
• and
• an electronic hardware controller configured to:
• selectively activate either the first mode or the second mode based on a thickness of a layer included in the object under test, the layer covering the at least one first structure,
• wherein the multi-channel energy unit generates the first protons or the second photons to penetrate through the layer and detect the at least one first structure based on the first mode or second mode selected by the controller.

A method of performing an overlay analysis between first and second structures included in an object under test, the method comprising:

• determining, via an electronic controller, that an intermediate layer is interposed between the first structure and the second structures;
• activating, via the controller, a multi-channel energy unit configured to operate in a first mode and a second mode, the first mode activated when a photon-blocking characteristic is present in the intermediate layer, and the second mode activated when the photon-block characteristic is excluded from the intermediate layer;
• delivering, via the multi-channel energy unit, first photons having a first wavelength to the object under test in response to activating the first mode to penetrate through the intermediate layer, and delivering, via the multi-channel energy unit, second photons having a second wavelength to the object under test in response to activating the second mode to penetrate through the intermediate layer, the second wavelength being different from the first wavelength;
• and
• generating an image displaying a first position of the second structure with respect to the first structure buried in the object under test and beneath the intermediate layer.