SENSOR MODULE, ILLUMINATOR, METROLOGY DEVICE AND ASSOCIATED METROLOGY METHOD

摘要

In a first aspect of the invention, there is provided a method of determining a parameter of interest of a structure on a substrate, said structure comprising at least one first feature oriented along a first axis of a structure coordinate system and at least one second feature oriented along a second axis of the structure coordinate system , the method comprising: illuminating the first feature and the second feature with first illumination from a first direction oblique to said first axis and second axis, so as to generate first scattered radiation from the first feature and second scattered radiation from the second feature, detecting a first interference pattern formed by interference between a portion of the first scattered radiation and first reference illumination; delecting a second interference pattern formed by interference between a portion of the second scattered radiation and the first reference illumination; and determining the parameter of interest of the structure using the first interference pattern, the second interference patlern. In a second aspect of the invention, there is provided holographic metrology apparatus comprising: a sensor module; a substrate support for supporting a substrate comprising a structure, the structure comprising at least one first feature oriented along a first axis of a structure coordinate system and at least one second feature oriented along a second axis of the structure coordinate system; and a reference illumination device for generating first reference illumination; wherein the sensor module comprises: an illumination device comprising at least one illuminator being operable to illuminate the structure with a first illumination from a first direction oblique to said first axis and second axis, so as to generate first scattered radiation from the first feature and second scattered radiation from the second feature; e an optical system being operable to capture said first scattered radiation and second scattered radiation; and a detector operable to detect a first interference pattern formed by interference between a portion of the first scattered radiation and first reference illumination and a second interference pattern formed by interference between a portion of the second scattered radiation and the first reference illumination.