Importance

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Abstract

Apparatuses and methods for evaluating microstructures on workpieces are disclosed herein. In one embodiment, a scatterometer comprises an irradiation source, an optic member, and an object lens assembly. The irradiation source can be a laser that produces a beam of radiation at a wavelength. The optic member is aligned with the path of the beam and configured to condition the beam (e.g., shape, randomize, select order, diffuse, converge, diverge, collimate, etc.), and the object lens assembly is positioned between the optic member and a workpiece site. The object lens assembly is configured to (a) simultaneously focus the conditioned beam through a plurality of altitude angles to a spot at an object focal plane, (b) receive radiation scattered from a workpiece, and (c) present a distribution of the scattered radiation at a second focal plane. The object lens assembly maintains a sine relationship between the altitude angles and corresponding points on the radiation distribution at the second focal plane. The scatterometer further includes a mask positioned between the optic member and the object lens assembly, and a detector positioned to receive at least a portion of the radiation distribution. The mask is aligned with the path of the beam to block a portion of the conditioned beam. The mask is configured to at least partially separate the zeroth-order diffraction and the higher-order diffractions in the radiation distribution at the second focal plane. The detector is configured to produce a representation of the radiation distribution.

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First Claim