Method and apparatus for X-ray and extreme ultraviolet inspection of lithography masks and other objects
First Claim
1. Apparatus for the inspection of an X-ray mask including an X-ray transparent substrate layer that allows X-rays to pass relatively unimpeded therethrough and X-ray absorbers positioned on the substrate layer in an absorber pattern through which X-rays are passed in a pattern, comprising:
- (a) a converter positioned to receive the X-rays in the pattern passed through the X-ray mask and to convert the pattern of X-rays received to a pattern of electrons emitted from the converter with the local intensity directly proportional to the local intensity of the X-rays impinging on the converter;
(b) an electron microscope positioned to receive the electrons emitted from the converter and having electron optics therein to magnify the pattern of electrons and provide a visible display of the magnified pattern;
(c) a camera receiving the visible display and providing an output signal corresponding thereto;
(d) a computer receiving the output signal and digitizing the output signal;
(e) a display connected to the computer to display the digitized image from the computer;
(f) means for storing a digitized as desired pattern of the X-ray mask; and
(g) means for comparing the as designed pattern to the digitized image.
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0 Petitions
Accused Products
Abstract
Inspection of objects such as X-ray lithography masks is carried out by passing X-rays or extreme ultraviolet light through an object which absorbs in a pattern to provide a patterned X-ray or ultraviolet image which is then directed to a converter. The converter converts the image incident upon it to an image formed by electrons emitted from the converter. The emitted electrons are magnified in an electron microscope and the magnified electron image is displayed by the electron microscope. The visible image may be further digitized and processed by a computer, including long-term storage or display on a computer monitor. X-ray lithography masks may be inspected by passing X-rays through masks of the same type that will be used for lithography so that the magnified image of the X-rays passed through the masks corresponds to the pattern of X-rays that will be incident on a photoresist, allowing accurate inspection of X-ray masks before use.
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Citations
17 Claims
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1. Apparatus for the inspection of an X-ray mask including an X-ray transparent substrate layer that allows X-rays to pass relatively unimpeded therethrough and X-ray absorbers positioned on the substrate layer in an absorber pattern through which X-rays are passed in a pattern, comprising:
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(a) a converter positioned to receive the X-rays in the pattern passed through the X-ray mask and to convert the pattern of X-rays received to a pattern of electrons emitted from the converter with the local intensity directly proportional to the local intensity of the X-rays impinging on the converter; (b) an electron microscope positioned to receive the electrons emitted from the converter and having electron optics therein to magnify the pattern of electrons and provide a visible display of the magnified pattern; (c) a camera receiving the visible display and providing an output signal corresponding thereto; (d) a computer receiving the output signal and digitizing the output signal; (e) a display connected to the computer to display the digitized image from the computer; (f) means for storing a digitized as desired pattern of the X-ray mask; and (g) means for comparing the as designed pattern to the digitized image. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for inspection of an X-ray lithography mask having a substrate layer and X-ray absorber material formed on the substrate in a pattern by X-rays, comprising the steps of:
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(a) passing X-rays through the X-ray mask such that the X-rays are more greatly absorbed by the absorber material in the pattern than the X-rays passed through the substrate between the absorber material so that the X-rays passed through the X-ray mask define an X-ray image; (b) directing the X-rays passed through the X-ray mask onto a converter to convert the X-ray image to a corresponding image formed by electrons emitted from the converter; and (c) magnifying the image of the emitted electrons by an electron microscope and displaying the magnified electron image. - View Dependent Claims (9, 10, 11, 12)
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13. A method for inspection of a lithography mask having material formed thereon for patterning radiation incident on the mask, comprising the steps of:
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(a) exposing the mask to radiation to pattern the radiation; (b) directing the patterned radiation into a converter to convert the patterned radiation to a corresponding patterned image formed by electrons emitted from the converter; (c) magnifying the image of the emitted electrons by an electron microscope; and (d) displaying the magnified electron image. - View Dependent Claims (14, 15, 16, 17)
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Specification