System and method for aerial image sensing
First Claim
1. A system for sensing at an increased resolution an aerial image exhibiting a light intensity distribution at a primary resolution, the system comprising:
- a photo-electron emission unit to sense the aerial image and, in response, emit electrons in a pattern corresponding to the light intensity distribution of the aerial image;
electron optics to project an enlarged pattern of the pattern of electrons emitted by the photo-electron emission unit;
a sensing unit to sense the enlarged pattern; and
an image analysis unit, coupled to the sensing unit, to digitize the enlarged pattern.
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Accused Products
Abstract
In one aspect, the present invention is a technique of, and a system and sensor for sensing an aerial image produced by, for example, optical lithographic equipment used in semiconductor fabrication. In one embodiment, the apparatus includes a negative electron affinity photo-electron emission device for projecting the aerial image thereon. In response, the photo-electron emission device emits electrons with a very tight energy spread in a pattern corresponding to the light intensity distribution produced by the aerial image. Electron optics is provided for guiding and projecting the electrons to form an enlarged pattern of the pattern in which the electrons are emitted. A sensing unit senses the enlarged pattern and supplies it to a device for capturing and digitizing the enlarged pattern to obtain therefrom a digitized aerial image. The resolution increase is achieved through the enlargement of the pattern by the electron optics.
In another embodiment, the apparatus employs a photo-conducting layer for projecting the aerial image thereon. The photo-conducting layer is made of a suitable semiconducting material to render it locally conducting in correspondence to the light intensity distribution of the aerial image, which, in response to the projection of the aerial image on the photo-conducting layer, produces local charge depletion in the photo-conducting layer corresponding to the light intensity distribution. The apparatus may also include an electron source for providing electrons and a device for delivering the electrons to the photo-conducting layer to produce local re-charging currents in proportion to the local charge depletion. The apparatus may derive a pattern corresponding to the aerial image from the re-charging currents.
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Citations
27 Claims
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1. A system for sensing at an increased resolution an aerial image exhibiting a light intensity distribution at a primary resolution, the system comprising:
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a photo-electron emission unit to sense the aerial image and, in response, emit electrons in a pattern corresponding to the light intensity distribution of the aerial image;
electron optics to project an enlarged pattern of the pattern of electrons emitted by the photo-electron emission unit;
a sensing unit to sense the enlarged pattern; and
an image analysis unit, coupled to the sensing unit, to digitize the enlarged pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A system for sensing an aerial image exhibiting a light intensity distribution at a primary resolution, the system comprising:
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a photo-conducting layer for projecting the aerial image thereon, wherein in response to the aerial image, the photo-conducting layer produces a depletion pattern corresponding to the light intensity distribution of the aerial image;
an electron source for providing electrons;
a steering device to direct the electrons to the photo-conducting layer to produce local re-charging currents in proportion to the local charge depletion;
amplifier circuitry coupled to the steering device, wherein the amplifier circuitry determines a pattern corresponding to the aerial image using the recharging currents; and
an image analysis unit, coupled to the sensing unit, to digitize the pattern. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification