Abstract: A method and apparatus for inspecting patterned transmissive substrates, such as photomasks, for unwanted particles and features occurring on the transmissive, opaque portions and at the transition regions of the opaque and transmissive portions of the substrate. A transmissive substrate is illuminated by a laser through an optical system comprised of a laser scanning system, individual transmitted and reflected light collection optics and detectors collect and generate signals representative of the light transmitted and reflected by the substrate as the substrate is scanned repeatedly in one axis in a serpentine pattern by a laser beam which is focused on the patterned substrate surface. The defect identification of the substrate is performed using only those transmitted and reflected light signals, and other signals derived from them, such as the second derivative of each of them.

Abstract: The present invention is a hybrid technique for finding defects on digitized device images using a combination of spatial domain and frequency domain techniques. The two dimensional spectra of two images are found using Fourier like transforms. Any strong harmonics in the spectra are removed, using the same spectral filter on both spectra. The images are then aligned, transformed back to the spatial domain, and subtracted. The resulting spectrally-filtered difference image is thresholded and analyzed for defects. Use of the hybrid technique of the present invention to process digitized images results in the highest-performance and most flexible defect detection system. It is the best performer on both array and random devices, and it can cope with problems such as shading variations and the dark-bright problem that no other technique can address.

Abstract: There is disclosed numerous embodiments of a method and apparatus for a particle scanning system and an automatic inspection system. In each of these a particle beam is directed at the surface of a substrate for scanning that substrate. Also included are a selection of detectors to detect at least one of the secondary particles, back-scattered particles and transmitted particles from the substrate. The substrate is mounted on an x-y stage to provide it with at least one degree of freedom while the substrate is being scanned by the/particle beam. The substrate is also subjected to an electric field on it's surface to accelerate the secondary particles. The system also has the capability to accurately measure the position of the substrate with respect to the charged particle beam. Additionally, there is an optical alignment means for initially aligning the substrate beneath the,particle beam means.

Abstract: A process for measuring overlay misregistration during semiconductor wafer fabrication including the use of an interferometric microscope in combination with a camera, a wafer transport stage, and data processing electronics to form an inspection system which can utilize either broadband or narrowband light, and large or small numerical aperture (NA) to develop a series of interference images taken at different Z (vertical) planes relative to the surface under investigation or P (pathlength) positions relative to interferometer arm difference. The data in these planes is then used to calculate the magnitude and phase of the mutual coherence between the object wave and the reference wave for each pixel in the image planes, and synthetic images are formed, the brightness of which is proportional to either the complex magnitude (the Magnitude Contrast Image or MCI) or the phase of the mutual coherence as the optical pathlength (the Phase Contrast Image or PCI) is varied.

Abstract: A method whereby the image produced in a coherence probe microscope is modified by means of a certain specific additive electronic transformation for the purpose of improving the measurement of selected features. The technique improves measurement accuracy on optically complex materials, in particular it improves the accuracy of linewidth measurement on semiconductor linewidths.

Abstract: An improved catadioptric imaging system is presented which produces a flat accessible final image, and is particularly effective at high speed in the deep ultraviolet spectral range. The lenses of the system are formed from a single glass type, fused silica. A first group of lenses serves as an aberration corrector group. A single focusing lens focuses light, transmitted through the corrector group, forming an intermediate image at a predetermined position within the system. A separate field lens is placed at the intermediate image point, and focuses the light transmitted thereto through a hole in the center of a spherical mirror. The light then travels through a separate thick lens element and is subsequently reflected by a planar mirror back through the thick lens and towards the concave reflective side of the spherical mirror. The spherical mirror thereafter reflects this incident light, focusing it through a hole in the center of the planar mirror and to a final imaging point outside of the system.

Abstract: An optomechanical system for illuminating and imaging selected portions of a three dimensional object having specularly reflective surfaces, including a two dimensional image sensor for receiving light reflected from the selected portions and producing an analog output signal representing a two dimensional image of the selected portions over a predetermined time period, a video digitizer for receiving and converting the analog output signal to a digital signal, and an image computer for receiving the digital signal output by the video digitizer, comparing the information obtained from the output digital signal to the stored specifications of a master of the imaged portion of the object, indicating whether the imaged object meets the specifications of the master, controlling the movement of the imaged object, and controlling the operation of the system.

Abstract: An instrument table having two features is disclosed. The first is a stable instrument bench that is constructed of sections of precast reinforced concrete. Each of these sections are then moisture sealed with a plastic coat or paint, then assembled using epoxy and bolts. The second element of the present invention is the replication of a precision surface on the table portion of an instrument bench.

Abstract: An automatic inspection system including an illuminator for illuminating a reticle or photomask to be inspected, while optically projecting a magnified image of the reticle or photomask onto a plurality of detector elements. A carriage assembly moves the object at a constant velocity to allow the detector elements to sequentially view the entire surface to be inspected. The detector elements are responsive to the intensity of light incident thereupon and are periodically scanned to obtain a two-dimensional measured representation of the object. A database adaptor formulates a two-dimensional representation from the design database description corresponding to the scanned object simultaneously and in synchronism with the scanning of the photomask or reticle. The measured and database adapted representation of the scanned object are input to a signal processor for alignment and defect detection.

Abstract: An instrument table having two features is disclosed. The first is a stable instrument bench that is constructed of sections of precast reinforced concrete. Each of these sections are then moisture sealed with a plastic coat or paint, then assembled using epoxy and bolts. The second element of the present invention is the replication of a precision surface on the table portion of an instrument bench.

Abstract: Substrate inspection apparatus and methods, and illumination apparatus. The inspection apparatus and method includes memory for storing the desired features of the surface of the substrate, focussed illuminator for substantially uniformly illuminating a region of the surface of the substrate to be inspected. Additionally there is a sensor for imaging the region of the substrate illuminated by the illuminator, and a comparator responsive to the memory and sensor for comparing the imaged region of the substrate with the stored desired features of the substrate. The illumination apparatus is designed to provide substantially uniform focussed illumination along a narrow linear region. This apparatus includes first, second and third reflectors elliptically cylindrical in shape, each with its long axis substantially parallel to the long axes of each of the others.

Abstract: A method of inspecting repeating pattern devices according to which an image of the patterns is aligned with an array of pixels in the image detection plane of an optical detector. The image is magnified to a scale so that features of patterns repeated in the image occupy corresponding pixels or groups of pixels repeated in the array. Data is resolved from selected pixels and directly compared either to data obtained from corresponding pixels or from a data base, whereby defective features are identified through well-known data comparison techniques.

Abstract: An optico-mechanical alignment apparatus having at least two optical paths, one with low resolution and one with high resolution providing an image to video image generator. The image forms a first data set that is compared to a second data set representative of the preferred alignment of an object to be aligned by a comparison means that can automatically move a stage mounting the object to be aligned in the X, Y and Z directions and rotate it in the X Y plane. The object is coarsely aligned with the low resolution optics and then finely aligned with the high resolution optics.

Abstract: A specially adapted Linnik microscope is used in combination with a video camera, a wafer transport stage and data processing electronics to form a novel inspection apparatus based on the use of the two beam interference microscope. The apparatus can utilize either broad band or narrow band light to develop a plurality of interference images taken at different axial positions relative to the surface under investigation. The point-by-point brightness along scan lines across such images is then used to develop data which is proportional to the degree of coherence (or to the fringe amplitude, the variance of the fringes, or the amplitude of oscillation of the fringes) as the optical path difference is varied in a two beam optical or acoustic microscope.

Abstract: A photomask and reticle inspection method and apparatus wherein a selected surface area of an object is inspected and a first stream of data having signal values representing the image content of each pixel thereof is generated, a second stream of data having signal values representing the intended image content of each pixel of the first stream of data is generated, corresponding portions of the first and second streams of data are stored in memory, any misalignment between the stored portions of the first and second streams of data is detected, the misaligned first and second portions of data are then aligned using shifts of an integral number of pixels and/or subpixel interpolation to correct the detected misalignment therebetween, corresponding subportions of the stored and aligned first and second portions of data are then compared to detect difference therebetween, and upon detecting a difference exceeding a predetermined threshold, the presence of a defect at a particular pixel location on the inspecte

Abstract: An optical emission microscopy system with a macro optic system having a high numerical aperture for obtaining global views of an integrated circuit Device Under Test (DUT). The DUT is subjected to illumination and stimulation conditions, and images are obtained to form a "global difference" image in which defects, wherever located in the chip, can be discerned by the system operator. The operator can select apparent "defect bright spots" to be further inspected, and zoom in with the higher magnification micro optics system to repeat the image formation steps. "Difference images" are processed to further eliminate noise spots using an improved two-stage filtering operation. The system may be operated under manual or automatic control, and may be interfaced to various data input, storage, and output devices as desired.

Abstract: An apparatus for storing and retrieving data in predetermined multi-bit length quantities containing fewer bits of data than word length quantities, including a memory for storing word length quantities at particular storage sites, a first buffer for selectively receiving data bits contained in a first predetermined portion of a word length quantity of data stored at a particular address within the memory, a second buffer for selectively receiving data bits contained in a second predetermined portion of the word length quantity of data stored at the particular address, a third buffer for alternatively receiving data bits contained in the second predetermined portion of the word length quantity of data stored at the particular address, a data bit generator for generating a null signal in the form of a predetermined number of data bits, a data bus having a first data transfer part and a second data transfer part connected to the memory, a CPU for causing the respective first and second portions of data and the

Abstract: In an automatic wafer inspection system, the objective lenses used in micro inspection are mounted on a turret which is attached to an adjustable turret support member. Several lenses may be brought sequentially into position for inspection of the patterned wafer and it is necessary that the handoff be precise so as to maintain the same pattern in the viewing position. V-slots are mounted on the turret in such a location as to be correctly associated with the precise position for each lens. A detent ball spring is biased to drive into a V-slot so as to hold the associated lens in the precise viewing position. When hand-off to the next lens is to be accomplished, a counter force is applied which overcomes the spring bias and pulls the detent ball out of the V-slot. A drive motor is then enabled, which turns the turret a predetermined distance to bring the wide opening of the next adjacent V-slot into approximate alignment with the detent ball and the drive motor is disabled.

Abstract: A system for automatic micro and macro inspection of patterned wafers, including a X-Y stage for supporting and positioning a wafer at a macro inspection station and a micro inspection station, a plurality of cassettes for storing a plurality of patterned wafers before and after inspection, a transfer arm and apparatus for transferring a wafer from the cassettes to a predetermined location on the X-Y stage, apparatus for centering the wafer on the macro inspection station, apparatus for aligning the wafer to obtain a preselected orientation for macro inspection, an optical system for effecting macro inspection of the wafer and storing a unique image thereof, apparatus for moving the wafer from the macro inspection station to the micro inspection station so that the area of the wafer corresponding to the stored unique image is in a micro optical path, autofocus apparatus for automatically focusing the lowest magnification objective lens on the area of the wafer to derive a real time image, a comparitor for com

Abstract: An automatic microscope focusing system including a light source 44, a dual channel fiber optics bundle 56 and 58, chopper means 54 for alternately admitting light to the channels, a reticle 66 and associated optics to cast alternating images onto the surface of an inspected article W, return masks 82 and 88, and associated detectors 86 and 92 for inspecting the alternating reticle images, and control circuitry 36 and 38 responsive to the detector outputs and operative to drive the system microscope 10 into focus. The preferred embodiment also includes a flipping pupil 60 for accommodating particular microscope objectives.