Uniform pupil illumination for optical inspection systems
AssigneeKLA-Tencor Technologies Corporation
InventorSteven R. Lange
Life of this patent
Estimating the term…
Abstract
An illuminator for uniformly illuminating an entrance pupil of an inspection system in order to increase inspection resolution and sensitivity and improve system-to-system matching is described. The illuminator incorporates at least two lightpipes for spatially and angularly distributing light rays from the illuminator uniformly across the entrance pupil. The illuminator also results in spatial and angular uniformity at the field stop plane. In one embodiment, one lightpipe has a circular shape and a second lightpipe has a rectangular shape.
Claims27
An illuminator for providing illumination in an inspection system comprising:
- an illumination source that emits light rays;
- a first lightpipe suitable for receiving the light rays from the illumination source and channeling the light rays wherein the spatial distribution of the light rays become randomized as the light rays travel through the first lightpipe;
- a second lightpipe for receiving the light rays as the light rays exit the first lightpipe, the second lightpipe being suitable for channeling the light rays wherein the spatial distribution of the light rays become randomized as the light rays travel through the second lightpipe;
- and
- wherein the light rays are substantially spatially uniformly distributed across a pupil and the angle of the light rays are substantially uniformly distributed across a range of incident angles at the pupil.
An illuminator for providing illumination in an inspection system comprising:
- an illumination source that emits light rays;
- a substantially circular lightpipe suitable for receiving the light rays from the illumination source and channeling the light rays wherein the spatial distribution of the light rays become randomized as the light rays travel through the circular lightpipe;
- a substantially rectangular lightpipe for receiving the light rays as the light rays exit the circular lightpipe, the rectangular lightpipe being suitable for channeling the light rays wherein the spatial distribution of the light rays become randomized as the light rays travel through the rectangular lightpipe;
- and
- a pupil or image of a pupil located at an end of the rectangular lightpipe where the light rays exit the rectangular lightpipe, wherein the light rays are substantially uniformly spatially distributed across the pupil and the angle of the light rays are substantially uniformly distributed across a range of incident angles at the pupil.
Dependencies are inferred from the claim text.