Patents by Inventor David R. Shafer
David R. Shafer has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6483638Abstract: An ultra-broadband ultraviolet (UV) catadioptric imaging microscope system with wide-range zoom capability. The microscope system, which comprises a catadioptric lens group and a zooming tube lens group, has high optical resolution in the deep UV wavelengths, continuously adjustable magnification, and a high numerical aperture. The system integrates microscope modules such as objectives, tube lenses and zoom optics to reduce the number of components, and to simplify the system manufacturing process. The preferred embodiment offers excellent image quality across a very broad deep ultraviolet spectral range, combined with an all-refractive zooming tube lens. The zooming tube lens is modified to compensate for higher-order chromatic aberrations that would normally limit performance.Type: GrantFiled: May 15, 2000Date of Patent: November 19, 2002Assignee: KLA-Tencor CorporationInventors: David R. Shafer, Yung-Ho Chuang, Bin-Ming B. Tsai
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Publication number: 20020085271Abstract: An ultraviolet (UV) catadioptric imaging system, with broad spectrum correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV (as short as about 0.16 &mgr;m), comprises a focusing lens group with multiple lens elements that provide high levels of correction of both image aberrations and chromatic variation of aberrations over a selected wavelength band, a field lens group formed from lens elements with at least two different refractive materials, such as silica and a fluoride glass, and a catadioptric group including a concave reflective surface providing most of the focusing power of the system and a thick lens providing primary color correction in combination with the focusing lens group. The field lens group is located near the intermediate image provided by the focusing lens group and functions to correct the residual chromatic aberrations. The system is characterized by a high numerical aperture (typ, greater than 0.Type: ApplicationFiled: November 6, 2001Publication date: July 4, 2002Applicant: KLA Instruments CorporationInventors: David R. Shafer, Yung-Ho Chuang, Bin-Ming B. Tsai
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Publication number: 20020039175Abstract: A projection exposure lens has an object plane, optical elements for separating beams, a concave mirror, an image plane, a first lens system arranged between the object plane and the optical elements for separating beams, a second double pass lens system arranged between the optical elements for separating beams and the concave mirror, a third lens system arranged between the optical elements for separating beams and the image plane. The second lens system has a maximum of five lenses.Type: ApplicationFiled: December 27, 2000Publication date: April 4, 2002Inventors: David R. Shafer, Wilhelm Ulrich, Helmut Beierl
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Publication number: 20020012100Abstract: The invention concerns a microlithographic reduction projection catadioptric objective having an even number greater than two of curved mirrors, being devoid of planar folding mirrors and featuring an unobscured aperture. The objective has a plurality of optical elements, and no more than two optical elements deviate substantially from disk form. The objective has an object side and an image side, and has in sequence from the object side to the image side a catadioptric group providing a real intermediate image, a catoptric or catadioptric group providing a virtual image, and a dioptric group providing a real image.Type: ApplicationFiled: January 12, 2001Publication date: January 31, 2002Inventor: David R. Shafer
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Publication number: 20020001141Abstract: An optical projection lens system comprising one lens with an aspherical surface and comprisingType: ApplicationFiled: December 21, 2000Publication date: January 3, 2002Inventors: David R. Shafer, Wilhelm Ulrich
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Publication number: 20010050820Abstract: An optical projection lens system comprising one lens with an aspherical surface and comprising a first bulge followed by a first waist followed by a second bulge, wherein the diameter of the second bulge is smaller than the diameter of the first bulge.Type: ApplicationFiled: January 4, 2001Publication date: December 13, 2001Inventors: David R. Shafer, Wilhelm Ulrich
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Publication number: 20010043391Abstract: A photolithographic reduction projection catadioptric objective includes a first optical group having an even number of at least four mirrors and having a positive overall magnifying power, and a second substantially refractive optical group more image forward than the first optical group having a number of lenses. The second optical group has a negative overall magnifying power for providing image reduction. The first optical group provides compensative aberrative correction for the second optical group. The objective forms an image with a numerical aperture of at least substantially 0.65, and preferably greater than 0.70 or still more preferably greater than 0.75.Type: ApplicationFiled: January 16, 2001Publication date: November 22, 2001Inventors: David R. Shafer, Russell Hudyma, Wilhelm Ulrich
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Publication number: 20010040722Abstract: A design for inspecting specimens, such as photomasks, for unwanted particles and features such as pattern defects is provided. The system provides no central obscuration, an external pupil for aperturing and Fourier filtering, and relatively relaxed manufacturing tolerances, and is suited for both broad-band bright-field and laser dark field imaging and inspection at wavelengths below 365 nm. In many instances, the lenses used may be fashioned or fabricated using a single material. Multiple embodiments of the objective lensing arrangement are disclosed, all including at least one small fold mirror and a Mangin mirror. The system is implemented off axis such that the returning second image is displaced laterally from the first image so that the lateral separation permits optical receipt and manipulation of each image separately.Type: ApplicationFiled: July 7, 1999Publication date: November 15, 2001Inventors: DAVID R. SHAFER, YUNG-HO CHUANG, J. JOSEPH ARMSTRONG
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Patent number: 6313467Abstract: An ultraviolet (UV) catadioptric imaging system, with broad spectrum correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV (as short as about 0.16 &mgr;m), comprises a focusing lens group with multiple lens elements that provide high levels of correction of both image aberrations and chromatic variation of aberrations over a selected wavelength band, a field lens group formed from lens elements with at least two different refractive materials, such as silica and a fluoride glass, and a catadioptric group including a concave reflective surface providing most of the focusing power of the system and a thick lens providing primary color correction in combination with the focusing lens group. The field lens group is located near the intermediate image provided by the focusing lens group and functions to correct the residual chromatic aberrations. The system is characterized by a high numerical aperture (typ. greater than 0.Type: GrantFiled: June 16, 2000Date of Patent: November 6, 2001Assignee: KLA-Tencor, Inc.Inventors: David R. Shafer, Yung-Ho Chuang, Bin-Ming B. Tsai
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Patent number: 6262826Abstract: An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements are characterized in order from object to image as convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention increases the slit dimensions associated with ringfield scanning optics, improves wafer throughput and allows higher semiconductor device density.Type: GrantFiled: January 4, 2000Date of Patent: July 17, 2001Assignee: The Regents of the University of CaliforniaInventor: David R. Shafer
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Patent number: 6188513Abstract: An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receive a chief ray at an incidence angle of less than substantially 9°, and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14°. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 &mgr;m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 &mgr;m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 &mgr;m.Type: GrantFiled: March 15, 1999Date of Patent: February 13, 2001Inventors: Russell Hudyma, David R. Shafer
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Patent number: 6142641Abstract: The invention is directed to a four-mirror catoptric projection system for extreme ultraviolet (EUV) lithography to transfer a pattern from a reflective reticle to a wafer substrate. In order along the light path followed by light from the reticle to the wafer substrate, the system includes a dominantly hyperbolic convex mirror, a dominantly elliptical concave mirror, spherical convex mirror, and spherical concave mirror. The reticle and wafer substrate are positioned along the system's optical axis on opposite sides of the mirrors. The hyperbolic and elliptical mirrors are positioned on the same side of the system's optical axis as the reticle, and are relatively large in diameter as they are positioned on the high magnification side of the system. The hyperbolic and elliptical mirrors are relatively far off the optical axis and hence they have significant aspherical components in their curvatures.Type: GrantFiled: June 18, 1998Date of Patent: November 7, 2000Assignees: Ultratech Stepper, Inc., The Regents of the University of CaliforniaInventors: Simon J Cohen, Hwan J Jeong, David R Shafer
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Patent number: 6133576Abstract: Broad spectrum ultraviolet inspection methods employ an achromatic catadioptric system to image the surface of an object, such as a semiconductor wafer or photomask, at multiple ultraviolet (UV) wavelengths over a large flat field (with a size on the order of 0.5 mm) in order to detect and identify defects. The imaging system provides broad band correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV. UV imaging applications include a method that illuminates an object with fluorescence-excitation radiation to stimulate fluorescent emission at a plurality of UV wavelengths, then images the fluorescent emissions and detects the images so formed in UV wavelength bands distributed over at least 50 nm (preferably 100-200 nm) wavelength. Photoresist patterns can be analyzed in this way.Type: GrantFiled: October 14, 1997Date of Patent: October 17, 2000Assignee: KLA Instruments CorporationInventors: David R. Shafer, Yung-Ho Chuang, Bin-Ming B. Tsai
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Patent number: 6014252Abstract: An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements are characterized in order from object to image as convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention increases the slit dimensions associated with ringfield scanning optics, improves wafer throughput and allows higher semiconductor device density.Type: GrantFiled: February 20, 1998Date of Patent: January 11, 2000Assignee: The Regents of the University of CaliforniaInventor: David R. Shafer
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Patent number: 5973826Abstract: An optical system compatible with short wavelength (extreme ultraviolet) An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.Type: GrantFiled: February 20, 1998Date of Patent: October 26, 1999Assignee: Regents of the University of CaliforniaInventors: Henry N. Chapman, Russell M. Hudyma, David R. Shafer, Donald W. Sweeney
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Patent number: 5956174Abstract: An ultraviolet (UV) catadioptric imaging system, with broad spectrum correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV (as short as about 0.16 .mu.m), comprises a focusing lens group with multiple lens elements that provide high levels of correction of both image aberrations and chromatic variation of aberrations over a selected wavelength band, a field lens group formed from lens elements with at least two different refractive materials, such as silica and a fluoride glass, and a catadioptric group including a concave reflective surface providing most of the focusing power of the system and a thick lens providing primary color correction in combination with the focusing lens group. The field lens group is located near the intermediate image provided by the focusing lens group and functions to correct the residual chromatic aberrations. The system is characterized by a high numerical aperture (type. greater than 0.Type: GrantFiled: January 15, 1998Date of Patent: September 21, 1999Assignee: KLA Instruments CorporationInventors: David R. Shafer, Yung-Ho Chuang, Bin-Ming B. Tsai
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Patent number: 5717518Abstract: An ultraviolet (UV) catadioptric imaging system, with broad spectrum correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV (as short as about 0.16 .mu.m), comprises a focusing lens group with multiple lens elements that provide high levels of correction of both image aberrations and chromatic variation of aberrations over a selected wavelength band, a field lens group formed from lens elements with at least two different refractive materials, such as silica and a fluoride glass, and a catadioptric group including a concave reflective surface providing most of the focusing power of the system and a thick lens providing primary color correction in combination with the focusing lens group. The field lens group is located near the intermediate image provided by the focusing lens group and functions to correct the residual chromatic aberrations. The system is characterized by a high numerical aperture (typ. greater than 0.Type: GrantFiled: July 22, 1996Date of Patent: February 10, 1998Assignee: KLA Instruments CorporationInventors: David R. Shafer, Yung-Ho Chuang, Bin-Ming B. Tsai
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Patent number: 5410434Abstract: The reflective projection system has a relatively wide field of view that comprises two concave and two convex spherical mirrors, situated in certain non-light-blocking positions with respect to one another, for deriving, with negligible image aberrations, a projected magnified or demagnified image over at least one of a range of magnification or demagnification power values between 3 and infinity that may be zoomed over this range. Such a reflective projection system, utilizing a high-power excimer laser radiation source, may be employed for ablating the surface of a substrate, such as the surface of the coating of a coated wafer, with a demagnified image of an object pattern defined by a mask, the radiation intensity of the demagnified image being sufficiently high to effect this ablation.Type: GrantFiled: September 9, 1993Date of Patent: April 25, 1995Assignee: Ultratech Stepper, Inc.Inventor: David R. Shafer
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Patent number: 5353322Abstract: Optimum solutions for three-mirror lenses for projection lithography cameras using X-ray radiation to image a mask on a wafer are represented as single points within regions of two-dimensional magnification space defined by the magnification of a convex mirror as one coordinate and the ratio of the magnifications of a pair of concave mirrors optically on opposite sides of the convex mirror as another coordinate. Lenses within region 30, 50, and preferably within region 40, 60, of such magnification space represent potential solutions that are optimizable by standard computer optical design programs and techniques to achieve extremely low distortion lenses having a resolution of about 0.1 micron or less. Two of these lens systems having large chief ray angles at the mask and chief rays inclined away from the optical axis of the lens system in a direction from the source toward the mask are described in more detail.Type: GrantFiled: May 20, 1993Date of Patent: October 4, 1994Assignee: Tropel CorporationInventors: John H. Bruning, Anthony R. Phillips, Jr., David R. Shafer, Alan D. White
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Patent number: 5220590Abstract: Optimum solutions for three-mirror lenses for projection lithography cameras using X-ray radiation to image a mask on a wafer are represented as single points within regions of two-dimensional magnification space defined by the magnification of a convex mirror as one coordinate and the ratio of the magnifications of a pair of concave mirrors optically on opposite sides of the convex mirror as another coordinate. Lenses within region 30, 50, and preferably within region 40, 60, of such magnification space represent potential solutions that are optimizable by standard computer optical design programs and techniques to achieve extremely low distortion lenses having a resolution of about 0.1 micron or less.Type: GrantFiled: May 5, 1992Date of Patent: June 15, 1993Assignee: General Signal CorporationInventors: John H. Bruning, Anthony R. Phillips, Jr., David R. Shafer, Alan D. White