Abstract: A variable modulated transfer function (MTF) design employing a variable gate voltage source for use in inspecting specimens is disclosed. The design applies a variable gate voltage to each pixel of a sensor, wherein applying the variable gate voltage to each pixel adjusts the MTF of the pixel. MTF adjustment improves adverse effects encountered during inspection, such as aliasing and maintaining contrast.

Abstract: A system for multiple mode imaging is disclosed. The catadioptric system has an NA greater than 0.65, and preferably greater than 0.9, highly corrected for low and high order monochromatic aberrations. The system employs unique illumination entrances and optics to collect reflected, diffracted, and scattered light over a range of angles. Multiple imaging modes are possible by varying the illumination geometry and apertures at the pupil plane. Illumination can enter the catadioptric optical sytems using an auxiliary beamsplitter or mirror, or through the catadioptric elements at any angle from 0 to 85 degrees from vertical. The system may employ a relayed pupil plane, used to select different imaging modes, provide simultaneous operation of different imaging modes, Fourier filtering, and other pupil shaping operations.

Abstract: A system and method for inspection is disclosed. The design includes an objective employed for use with light energy having a wavelength in various ranges, including approximately 266 to 1000 nm, 157 nm through infrared, and other ranges. The objective comprises a focusing lens group comprising at least one focusing lens configured to receive light, a field lens oriented to receive focused light energy from said focusing lens group and provide intermediate light energy, and a Mangin mirror arrangement positioned to receive the intermediate light energy from the field lens and form controlled light energy. Each focusing lens has a reduced diameter, such as a diameter of less than approximately 100 mm, and a maximum corrected field size of approximately 0.15 mm. An immersion substance, such as oil, water, or silicone gel, may be employed prior to passing controlled light energy to the specimen inspected.

Abstract: A system for use with a reduced size catadioptric objective is disclosed. The system including the reduced size objective includes various subsystems to allow enhanced imaging, the subsystems including illumination, imaging, autofocus, positioning, sensor, data acquisition, and data analysis. The objective may be employed with light energy having a wavelength in the range of approximately 190 nanometers through the infrared light range, and elements of the objective are less than 100 mm in diameter. The objective comprises a focusing lens group and at least one field lens oriented to receive focused light energy from the focusing lens group and provide intermediate light energy. The objective also includes a Mangin mirror arrangement. The design imparts controlled light energy with a numerical aperture in excess of 0.65 and up to approximately 0.90 to a specimen for imaging purposes, and the design may be employed in various environments.

Abstract: 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.

Abstract: A reduced size catadioptric objective and system is disclosed. The objective may be employed with light energy having a wavelength in the range of approximately 190 nanometers through the infrared light range. Elements are less than 100 mm in diameter. The objective comprises a focusing lens group configured to receive the light energy and comprising at least one focusing lens. The objective further comprises at least one field lens oriented to receive focused light energy from the focusing lens group and provide intermediate light energy. The objective also includes a Mangin mirror arrangement positioned to receive the intermediate light energy from the field lens and form controlled light energy for transmission to a specimen. The Mangin mirror arrangement imparts controlled light energy with a numerical aperture in excess of 0.65 and up to approximately 0.90, and the design may be employed in various environments.

Abstract: A system and method for reducing peak power of a laser pulse and reducing speckle contrast of a single pulse comprises a plurality of beamsplitters, mirrors and delay elements oriented to split and delay a pulse or pulses transmitted from a light emitting device. The design provides the ability to readily divide the pulse into multiple pulses by delaying the components relative to one another. Reduction of speckle contrast entails using the same or similar components to the power reduction design, reoriented to orient received energy such that the angles between the optical paths are altered such that the split or divided light energy components strike the target at different angles or different positions. An alternate embodiment for reducing speckle contrast is disclosed wherein a single pulse is passed in an angular orientation through a grating to create a delayed portion of the pulse relative to the leading edge of the pulse.

Abstract: A system and method for inspecting a specimen, such as a semiconductor wafer, including illuminating at least a portion of the specimen using an excimer source using at least one relatively intense wavelength from the source, detecting radiation received from the illuminated portion of the specimen, analyzing the detected radiation for potential defects present in the specimen portion.

Abstract: A system and method for reducing peak power of a laser pulse and reducing speckle contrast of a single pulse comprises a plurality of beamsplitters, mirrors and delay elements oriented to split and delay a pulse or pulses transmitted from a light emitting device. The design provides the ability to readily divide the pulse into multiple pulses by delaying the components relative to one another. Reduction of speckle contrast entails using the same or similar components to the power reduction design, reoriented to orient received energy such that the angles between the optical paths are altered such that the split or divided light energy components strike the target at different angles or different positions. An alternate embodiment for reducing speckle contrast is disclosed wherein a single pulse is passed in an angular orientation through a grating to create a delayed portion of the pulse relative to the leading edge of the pulse.

Abstract: A system for multiple mode imaging is disclosed herein. The system is a catadioptric system preferably having an NA greater than 0.9, highly corrected for low and high order monochromatic aberrations. This system uses unique illumination entrances and can collect reflected, diffracted, and scattered light over a range of angles. The system includes a catadioptric group, focusing optics group, and tube lens group. The catadioptric group includes a focusing mirror and a refractive lens/mirror element. The focusing optics group is proximate to an intermediate image, and corrects for aberrations from the catadioptric group, especially high order spherical aberration and coma. The tube lens group forms the magnified image. Different tube lens groups can be used to obtain different magnifications, such as a varifocal tube lens group to continuously change magnifications from 20 to 200×. Multiple imaging modes are possible by varying the illumination geometry and apertures at the pupil plane.

Abstract: 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.

Abstract: A system for multiple mode imaging is disclosed. The catadioptric system has an NA greater than 0.65, and preferably greater than 0.9, highly corrected for low and high order monochromatic aberrations. The system employs unique illumination entrances and optics to collect reflected, diffracted, and scattered light over a range of angles. Multiple imaging modes are possible by varying the illumination geometry and apertures at the pupil plane. Illumination can enter the catadioptric optical system using an auxiliary beamsplitter or mirror, or through the catadioptric elements at any angle from 0 to 85 degrees from vertical. The system may employ a relayed pupil plane, used to select different imaging modes, provide simultaneous operation of different imaging modes, Fourier filtering, and other pupil shaping operations.

Abstract: 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.

Abstract: A system for multiple mode imaging is disclosed herein. The system is a catadioptric system preferably having an NA greater than 0.9, highly corrected for low and high order monochromatic aberrations. This system uses unique illumination entrances and can collect reflected, diffracted, and scattered light over a range of angles. The system includes a catadioptric group, focusing optics group, and tube lens group. The catadioptric group includes a focusing mirror and a refractive lens/mirror element. The focusing optics group is proximate to an intermediate image, and corrects for aberrations from the catadioptric group, especially high order spherical aberration and coma. The tube lens group forms the magnified image. Different tube lens groups can be used to obtain different magnifications, such as a varifocal tube lens group to continuously change magnifications from 20 to 200×. Multiple imaging modes are possible by varying the illumination geometry and apertures at the pupil plane.

Abstract: A system for imaging is disclosed herein. The system has a numerical aperture (NA) preferably greater than 0.9, but greater than 0.65, and uses unique illumination entrances to collect reflected, diffracted, and scattered light over a range of angles. The system includes a catadioptric group, focusing optics group, and tube lens group. Illumination can enter the catadioptric optical system using an auxiliary beamsplitter or mirror, or through the catadioptric group at any angle from 0 to 85 degrees from vertical. The high NA catadioptric system can also have a relayed pupil plane, used to select different imaging modes, providing simultaneous operation of different imaging modes, Fourier filtering, and other pupil shaping operations.

Abstract: 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.

Abstract: Disclosed is a method and apparatus for using far field scattered and diffracted light to determine whether a collection of topological features on a surface (e.g., a semiconductor wafer) conforms to an expected condition or quality. This determination is made by comparing the far field diffraction pattern of a surface under consideration with a corresponding diffraction pattern (a "baseline"). If the baseline diffraction pattern and far field diffraction pattern varies by more than a prescribed amount or in characteristic ways, it is inferred that the surface features are defective. The method may be implemented as a die-to-die comparison of far field diffraction patterns of two dies on a semiconductor wafer. The portion of the far field scattered and diffracted light sensitive to a relevant condition or quality can also be reimaged to obtain an improved signal-to-noise ratio.

Abstract: A system for multiple mode imaging is disclosed herein. The system is a catadioptric system preferably having an NA greater than 0.9, highly corrected for low and high order monochromatic aberrations. This system uses unique illumination entrances and can collect reflected, diffracted, and scattered light over a range of angles. The system includes a catadioptric group, focusing optics group, and tube lens group. The catadioptric group includes a focusing mirror and a refractive lens/mirror element. The focusing optics group is proximate to an intermediate image, and corrects for aberrations from the catadioptric group, especially high order spherical aberration and coma. The tube lens group forms the magnified image. Different tube lens groups can be used to obtain different magnifications, such as a varifocal tube lens group to continuously change magnifications from 20 to 200.times.. Multiple imaging modes are possible by varying the illumination geometry and apertures at the pupil plane.