High resolution imagery systems and methods
First Claim
1. A system for producing a highly corrected optical image comprising:
- substantially monochromatic light source means providing a plurality of light sources having limited spatial coherence and substantial temporal coherence within a distributed light beam area;
an optical system within the path of the light beam and having an aperture stop; and
microlithographic phase transmission grating means at the aperture stop, the grating means including a microstructure comprising a plurality of sets of plateaus, the light beam being disposed to provide light distributed through the optical system and the sets of plateaus of the grating means.
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Accused Products
Abstract
The current limits of resolution of multi-element optical systems are exceeded by reducing the number of elements while introducing at the critical aperture a blazed transmission grating having grating rings of low bending power defined by multiple plateaus. By illuminating the optical train with monochromatic light that constitutes a multiplicity of distributed sources having a substantial temporal coherence but spatial incoherence and by varying the slopes and widths of the grating rings, local phase delays are introduced that adjust aberrations in the optical system, providing an aligned composite wavefront. The system and method may be used for presenting an image, as for a wafer stepper, or for viewing an image, as in a microscope.
197 Citations
44 Claims
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1. A system for producing a highly corrected optical image comprising:
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substantially monochromatic light source means providing a plurality of light sources having limited spatial coherence and substantial temporal coherence within a distributed light beam area; an optical system within the path of the light beam and having an aperture stop; and microlithographic phase transmission grating means at the aperture stop, the grating means including a microstructure comprising a plurality of sets of plateaus, the light beam being disposed to provide light distributed through the optical system and the sets of plateaus of the grating means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An optical system for providing a desired light distribution at a chosen surface, the system comprising:
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light source means providing a wavefront of light that is temporally coherent to a selected number of waves and of limited spatial coherence; optical lens means disposed in the path of the light for refracting the light to form a wavefront providing an approximation of the desired light distribution at the chosen surface, the wavefront having local phase variations therein arising from aberrations in the lens means; and phase plate means including multi-level transmission grating means disposed with the optical lens means for locally phase retarding the wavefront to a substantially smaller degree than the number of waves of temporal coherence to obtain the desired wavefront and light distribution at the chosen surface. - View Dependent Claims (17)
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18. An optical system for providing a desired light distribution at a chosen surface, the system comprising:
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light source means comprising means for providing pulse sequences of light and providing a wavefront of light that is temporally coherent to a selected number of waves and of limited spatial coherence; optical lens means disposed in the path of the light for refracting the light to form a wavefront providing an approximation of the desired light distribution at the chosen surface; phase plate means disposed with the optical lens means for locally phase retarding the wavefront to a substantially smaller degree than the number of waves of temporal coherence to obtain the desired light distribution at the chosen surface; means responsive to the light for sensing the degree of spatial coherence and; means responsive to the sensed degree of spatial coherence for controlling the means for decreasing the same. - View Dependent Claims (19)
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20. An optical system for providing a desired light distribution at a chosen surface, the system comprising:
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coherent light source means providing a wavefront of light that is temporally coherent to in excess of about 10,000 waves and of limited spatial coherence, the light source means providing of the order of 102 point sources of light on each point at the image plane; means for controllably decreasing the spatial coherence in the light from the light source means; optical lens means disposed in the path of the light for refracting the light to form a wavefront providing an approximation of the desired light distribution at the chosen surface, the spherical aberration of the optical lens means being limited to about 75 waves or less maximum difference from a spherical aberration-free condition; and phase plate means disposed with the optical lens means for locally phase retarding the wavefront to a substantially smaller degree than the number of waves of temporal coherence to obtain the desired light distribution at the chosen surface.
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21. A system for precision imaging of light energy comprising:
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means providing illumination in the form of a multiplicity of independent light sources of substantially the same wavelength throughout a beam area; a plurality of refractive lens elements together providing light imaging with a predetermined spherical type aberration; and transmission grating means cooperative with the refractive lens elements for phase delaying and redirection of waves from the multiplicity of independent light sources to compensate by locally varying phase retardation for the spherical type aberration of the refractive lens elements such that a compensated composite wavefront is provided. - View Dependent Claims (22, 23, 24)
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25. A system for precision adjustment of the shape of the wavefront of a beam of light energy comprising:
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means providing illumination in the form of a multiplicity of light sources of substantially the same wavelengths throughout a beam area; a plurality of refractive lens elements in the path of the beam illumination and together providing light imaging with predetermined aberration characteristics which vary symmetrically as a predetermined function of the ray height at the aperture stop, but providing a high degree of correction for aberration components which vary as the image height or as the angular orientation of the ray meridian at the aperture stop; and transmission grating means at the aperture stop in the path of the beam illumination and cooperative with the refractive lens elements for phase delay and redirection of the illumination in accordance with a second predetermined function of the ray height at the aperture stop and compensating for the predetermined aberration characteristics of the refractive lens elements which vary symmetrically as a predetermined function of the ray height. - View Dependent Claims (26)
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27. A system for providing a precisely compensated monochromatic image on a semiconductor wafer comprising:
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a series of refractive lens elements disposed along an optical axis and having an aperture stop, the cumulative spherical type aberration being no greater than about 75 waves and the cumulative chromatic dispersion being positive; a transmission grating disposed at the aperture stop, the grating having a plurality of rings each with multiple plateaus providing local wavefront compensation for the spherical type aberration and a compensating negative chromatic dispersion for light of a predetermined wavelength; and illuminating means directing substantially monochromatic light along the optical axis, the substantially monochromatic light being of the predetermined wavelength and having temporal coherence of the order of 10,000 waves and being substantially spatially incoherent. - View Dependent Claims (28, 29, 30, 31, 32)
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33. An optical system for providing precise aspheric correction of a composite wavefront having aberrations from idealized specifications comprising:
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a transmissive blazed grating plate having a microlithographic pattern of incrementally varying narrow tracks, adjacent tracks varying differentially in height, the maximum differential height of the tracks on the plate being proportioned to the ratio of one wavelength of incident monochromatic light at a selected wavelength divided by the difference of the index of refractive of the plate from unity, the widths of the tracks through the pattern being proportioned to provide local phase delay of the wavefront according to a predetermined function for the composite wavefront to effect redistribution of the microstructure of the wavefront, the widths being precise to within about 1/20th wavelength of the monochromatic light; and means for illuminating the pattern on the plate with monochromatic light of the selected wavelength, the light having predictable periodicity and constituting multiple phase random sources. - View Dependent Claims (34, 35, 36, 37, 38, 39)
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40. A system for high resolution imagery on an object being illuminated comprising:
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an optical system having an aperture stop; first substantially monochromatic light source means of a given wavelength transmitting through the optical system; light bending means including a first transmission grating structure disposed at the aperture stop for providing a really distributed varying wave delays in light of the first wavelength transmitted through the optical system to provide an adjusted composite wavefront, said light bending means also including a second transmission grating structure displaced from the first transmission grating structure; and second monochromatic light source means of a second wavelength illuminating the second transmissive grating structure for alignment of the object being illuminated relative to the optical system. - View Dependent Claims (41, 42, 43, 44)
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Specification