Patent ID: 7428063
Filing Date: 2008-09-23
Classification: G03F

Abstract:
1. An overlay measurement apparatus comprising: a light source that emits light having a wide wavelength band; a wavelength switching mechanism, arranged in the illumination light path, that switches light emitted from said light source to light in a measurement wavelength range having a predetermined wavelength range or light in an evaluation wavelength range having a wavelength range different from said measurement wavelength range; a first measuring unit that captures images of a first mark and a second mark formed in different layers of a substrate illuminated by light in said measurement wavelength range being switched by said wavelength switching mechanism, and finds an overlay displacement between the first mark and the second mark based on the images in the measurement wavelength range; a second measuring unit that captures the images of said first mark and said second mark illuminated by light in said evaluation wavelength range being switched by said wavelength switching mechanism, and finds an overlay displacement between said first mark and said second mark based on the images in the evaluation wavelength range; and a calculation unit that calculates an index for accuracy of the overlay displacement in said measurement wavelength range according to the overlay displacement in said measurement wavelength range found by said first measuring unit and to the overlay displacement in said evaluation wavelength range found by said second measuring unit.