Method and apparatus for detecting defects in repeated microminiature patterns
AssigneeKLA Instruments Corporation
InventorsBin-ming B. Tsai, Fred E. Babian
Life of this patent
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Abstract
A method of inspecting repeating pattern devices according to which an image of the patterns is aligned with an array of pixels in the image detection plane of an optical detector. The image is magnified to a scale so that features of patterns repeated in the image occupy corresponding pixels or groups of pixels repeated in the array. Data is resolved from selected pixels and directly compared either to data obtained from corresponding pixels or from a data base, whereby defective features are identified through well-known data comparison techniques.
Claims14
A method of detecting defects in microminiature patterns repeated over a particular surface area of an object such as a semiconductor wafer, photomask, reticle or flat panel TV screen, comprising the steps of:
- providing an image detection means capable of resolving the information content of each pixel of an array of m.times.n pixels of a light image projected thereupon;
- illuminating an object having illuminatable feature determining patterns repeated in a regular array over a surface area thereof;
- projecting a focused image of light reflected from said surface area onto said detection means;
- rotating said object relative to said detection means so that an axis of said image is aligned with an axis of said detection means;
- adjusting the magnification of said image such that the dimension of the period of said repeated patterns in said image is equivalent to the distance across a selected integer number of pixels of said m.times.n array;
- and
- comparing one repeated feature to another to detect said defects.
A method of detecting defects in microscopic features in patterns repeated across a given surface area of an object such as a semiconductor wafer, photomask, reticle or flat panel TV screen, comprising the steps of:
- providing an image detection means having a field of view with an array of m.times.n pixels capable of resolving the information content of a light image projected onto said field;
- illuminating an object surface area on which an array of regularly repeated patterns display illuminatable features;
- focussing light from said surface area into an image projected onto said field of view of said detection means;
- using said image detection means to detect said image;
- repositioning said object surface relative to said detection means to align a selected axis of said image with a selected axis of said array of pixels;
- magnifying said image to scale the pitch of said patterns to correspond to the width of a selected number of pixels;
- resolving, with said detection means, the information content of selected pixels;
- and
- comparing one said feature in one pattern to another in another pattern to identify defects in said one feature.
Dependencies are inferred from the claim text.