Abstract: A method and apparatus for predicting the number of contaminant particles in circuit area of a patterned semiconductor wafer having a number of reflective circuit areas. The method includes forming on a wafer in specified areas, a grating test pattern, such as a line grating. The grating patterns are formed at the same time and in the same manner that repetitive circuit patterns are formed on the wafer. The wafer is then scanned by a light beam. Since the diffraction pattern caused by the grating test patterns is known, it is possible to detect when the light beam is scanning one of the known grating patterns. The diffraction pattern may be inspected for fabrication derived variations. In response to detecting a known grating pattern, a detection mechanism is activated. Since the diffraction pattern is known it may be spatially separated. In this way only light scattered by particles or defects in the pattern are collected and detected.

Abstract: A method for fabricating a microtip, cantilevered from a base and having a controllably high aspect ratio, for use in microprobe microscopy to probe variations in materials at the atomic level. A two-layer semiconductor material structure is provided, one layer being n type and the other layer being p type. A thin pencil of ions of n type is implanted through the n type layer into the p type layer, through a small aperture in a mask layer that overlies the n type layer. The p type material is then etched away, leaving the n type ion profile and the n type layer as a cantilevered microtip. The n type semiconductor layer may be replaced by a layer of any material that resists etching by the selected etchant.

Abstract: An apparatus and method using laser induced shock waves to dislodge particles from a wafer surface. The apparatus includes a wafer support, a particle detector and computer for locating and storing the locations of particles on the wafer, a laser, and focusing optics. Laser beam pulses are directed toward the wafer surface at a shallow angle or with a large beam convergence angle to avoid damage to the wafer.

Abstract: Methods for determining the presence or absence of, and the thickness or other spacial extent of, a contaminant layer at each of a plurality of two or more sites on the surface of an electrically conductive material such as a semiconductor, a metal or a metal silicide. The invention uses a change in photoemission current from an illuminated spot on the surface to determine the presence and extent of a contaminant layer at the illuminated site. Compensation is provided for the effects of capacitive current and photovoltaic current. The invention provides a pattern of illumination sites on the conductor surface that can, if desired, cover all points on the surface.

Abstract: Method and apparatus for determining the amount, if any, of residue remaining at the bottom of an aperture in a layer of dielectric or insulator material. A layer of electrically conducting material is positioned adjacent to the aperture bottom, an electron collector is positioned adjacent to the mouth of the aperture, and a voltage difference (optional) is impressed between the conducting material and the electron collector. The aperture bottom is illuminated with a light beam with photon energy greater than the electron work function of the conducting material, and a portion of the photons that comprise the light beam reach the conducting material and produce photoelectrons by photoemissive action. A photoelectron current is sensed by the electron collector, and the cleanliness of the aperture bottom is determined from the value of the current.

Abstract: A method and apparatus for detecting and classifying particles on a surface in which condensation is used to enlarge particles. An apparatus of the present invention includes a heatable wick disposed over a test surface and in fluid communication with a source of volatile liquid. A zone of vapor supersaturation is thus created in which condensation on particles on the surface can occur. A light beam directed onto the surface scans the surface. Droplets are detected by means of light scattered from the droplets. In an alternate embodiment a stream of carrier gas may be provided around the wick or bubbled through a jar of volatile liquid to direct a vapor toward the test surface. In another embodiment, multiple wicks communicate with different sources of volatile liquids. In a method of the invention, mulitple scans are made with either different levels of vapor supersaturation or different vapor compositions.

Abstract: An end-viewed vapor discharge lamp having a differential temperature control structure that removes heat more effectively from a base end of the lamp than from the light emitting output end of the lamp. The lamp envelope which contains an excitable vapor, such as mercury, includes a small bore capillary tube with a window at one end. A large bore extension contiguous with the capillary tube and a parallel second tube contain electrodes for providing a discharge in the capillary tube. A thermally conductive shell surrounds and is spaced apart from sides of the envelope and is partly filled with a thermally conductive material around the base end of the envelope. The output end around the capillary tube is free of this material. Heat conduction is better at the base end so that the capillary tube runs hotter, inhibiting condensation of vapor and giving a stable light output. An optional heater pad may be provided around the shell for maintaining an optimal temperature for maximum light output.

Abstract: A particle detection on a periodic patterned surface is achieved in a method and apparatus using a single light beam scanning at a shallow angle over the surface. The surface contains a plurality of identical die with streets between die. The beam scans parallel to a street direction, while a light collection system collects light scattered from the surface with a constant solid angle. The position of the collection system as well as the polarization of the light beam and collected scattered light may be arranged to maximize the particle signal compared to the pattern signal. A detector produces an electrical signal corresponding to the intensity of scattered light that is colelcted. A processor constructs templates from the electrical signal corresponding to individual die and compares the templates to identify particles. A reference template is constantly updated so that comparisons are between adjacent die.

Abstract: A method of measuring thin film thickness, especially on semiconductor substrates, in which the substrate is illuminated with ultraviolet light of a fixed wavelength corresponding to a persistent spectral line and the amount of light reflected from the substrate is detected and measured. The ultraviolet light preferably has a wavelength in the range from 240 nm to 300 nm, and the 253.6 nm spectral line of mercury is considered best. Comparing the measured amount of light from the substrate to a known amount of light detected from a standard calibration substrate with known reflectivity, the reflectivity of the test substrate is computed. The thickness of a thin film on the substrate is determined from the computed reflectivity using Fresnel's equation or a lookup table derived from the same.

Abstract: An end-viewed low-pressure gas discharge lamp and an envelope for said lamp having a capillary tube discharge bore for containing an excitable gas in which the capillary tube is in direct contact with a cooling medium. A window of optical quality fused silica, a thin section of bubble and particle free glass blown quality silica or sapphire is disposed on an end of the capillary tube for emitting light from a discharge of the excitable gas. A pair of electrodes are hermetically sealed through the envelope for producing a discharge in the capillary tube between the electrodes. The envelope may include a return path parallel to the capillary tube or a side tube as a means for connecting the two ends of the capillary tubes with the electrodes without obstructing the end view of the discharge. Filling the envelope with an excitable mixture of one or more gases, such as vaporized mercury, to a less than atmospheric pressure, and connecting the electrodes to a power supply completes the lamp.

Abstract: An optical scanning device for flaw detection or the like having a suspension system including at least two pairs of flexure legs. A first pair has flexure legs diagonally crossed in spaced-apart relation and fixed at one end to a stationary body and at an opposite end to a vibratory body. A second pair of spaced-apart cross-flexure legs link the stationary base to a magnetic driver for varying the angular position of the vibratory body about an axis of rotation. Each of the four flexure legs has a radial stiffness exceeding a torsional stiffness. The first pair of cross-flexure legs and the supported mass have characteristics corresponding to the characteristics of the second pair of cross-flexure legs and associated mass, thereby providing identical resonant frequencies of distortional bending. Any torque exerted on the stationary base by the first pair of cross-flexure legs is compensated by a torque which is equal in magnitude but opposite in direction translated through the second pair of flexure legs.

Abstract: A confocal measuring microscope including a spectrometer and autofocus system sharing common optical elements in which the intensity of light entering the spectrometer from a particular spot on a workpiece is used to determine a focus condition for the same spot. The microscope includes at least one light source, an illumination field stop, and a microscope objective that images the stop onto a workpiece supported by a movable platform. The objective also forms an image of the illuminated portion of the object. An aperture in a second stop and intersecting the image plane passes light from part of the image to the spectrometer, while viewing optics are used to view the image. In one embodiment, a detector is placed at the zero order position, while in another embodiment a laser is placed at the zero order position. In the later embodiment an integrator circuit connected to the detector array replaces the zero order detector for measuring the total intensity of light entering the spectrometer.

Abstract: A particle detection method for matching particles detected in two scans of a surface taken at different times in which particles having a light scattering intensity above a collection threshold are first detected and the measured position and scattering intensity therefor stored in a computer memory. Corresponding first and second measured positions from the respective first and second scans are determined by forming a triangle from selected first detected particles and finding those second detected particles which form a variant triangle with matching perimeter and area. From these matching first and second particles a transformation is found for mapping first measured positions to corresponding second positions and vice versa. Areas around corresponding positions of particles having a scattering intensity above a display threshold are examined for matching particles. If not found, the area is reexamined at a reduced threshold.

Abstract: A system for finding the orientation of a substantially circular disk shaped wafer with at least one flat region on an edge thereof, in which the wafer is spun one 360 degree turn on a chuck and the edge position is measured by a linear array to obtain a set of data points at various wafer orientations. The rotation axis may differ from the wafer center by an unknown eccentricity. The flat angle is found by fitting a cosine curve to the data, subtracting the expected data derived from the cosine curve from the actual data to obtain a deviation. The angle of maximum deviation of the data from the cosine curve is a first estimate of the flat angle. The estimate may be corrected for errors due to a finite number of data points and wafer eccentricity by calculating an adjustment angle from data points on the wafer flat. After determining the flat angle, the wafer is spun to the desired orientation.

Abstract: A method and apparatus for particle detection and position correlation that fuses separate detections of the same particle on adjacent scan lines into one. A first scan line on a surface is scanned with a laser beam and the scattered light detected. The detection generates address and amplitude data for each particle which is stored. The second line scanned also generates data which is stored in a buffer. Particle data between scan lines is compared. Data for new particles is stored, data for previous particles no longer detected being sent to computer storage, and data for the same particle being compared and only the one with larger amplitude being kept. The results in computer storage may be displayed as a wafer with those pixels lit which have particles.

Abstract: A first thermally conductive plate holds an article and heats the article with heating elements in the plate. Parallel rails support the first plate above a base. Cooling passageways for coolant flow are in a second thermally conductive plate. The second plate is supported spaced from the base by a shaft in a chamber of the second plate and a spring. During the heating phase, the second plate is spaced apart from the first plate. During the cooling phase, the second plate is urged by the spring into contact with the first plate, so that the second plate acts as a heat sink for the first plate. Vacuum suction and an annular elastomer seal around the top rim of the second plate clamp the first and second plates together in thermal communication. Vacuum suction in the chamber retracts the second plate from the first plate.

Abstract: A two-stage light collector, including a first stage which admits a scanning beam and a second stage which is optically connected to the first stage and has a light detector therein. The first stage has a shape which re-images diffusely scattered radiation from a target on which the radiation impinges. The first stage directs light toward an entrance aperture in the second stage which indirectly reflects light toward the detector associated with the second stage.

Abstract: A wafer handler featuring a carriage movable along a rail path, the carriage supporting an upright rotatable arm with a cantilevered wafer chuck. Elevators for raising and lowering trays containing wafer stacks are disposed on either side of the rail path. Each elevator has a curved track section which may be interposed along the rail path. The upright arm has a track follower, parallel to a boom supporting the wafer chuck and freely movable along the rail path, except when it encounters a curved track section. In this instance, the track follower will follow the curved track section, causing rotation of the arm, boom and wafer chuck, bringing the chuck into the wafer stack at an elevation determined by the elevator. In this manner, motion in the X, Y and Z planes may be provided for stacked wafers over extended distances.

Abstract: A flaw detector for optically transmissive surfaces having a first light collector above the surface and a second light collector below the surface. A scanning light beam is directed into the first light collector through a beam entrance aperture and only light scattered from the surface is collected. Light specularly reflected from the surface exits the collector through the beam entrance aperture. Similarly, light passing through the surface enters the second collector, but the axial beam component is dumped through an opening in the second collector, while only diffracted light is collected. Preferably, two-stage light collectors are used with the first stage admitting the beam and generating a scattered or diffracted beam component, with the second stage admitting the scattered or diffracted beam component and integrating the component over a collection surface and sampling the integrated portion at a photoelectric detector. An electrical output signal from the detector may be displayed.

Abstract: A test device for calibrating an optical scanner wherein microscopic patterns of light scattering elements simulate the scattering of light from particles or flaws of different sizes. Simulation of different particles sizes is achieved by means of clusters or arrays of these light scattering elements having different areawise densities. Patterns of such clusters or arrays are disposed on a surface with intervening spaces where a random assortment of foreign particles may be expected. In this manner, the foreign particles may be directly compared to a test pattern. The test surface may be a semiconductor wafer having a thin, inert coating with openings therein forming the light scattering elements. The openings may be made by photolithographic techniques, i.e., masking and etching, so that various patterns on a surface may be all created simultaneously by the same process.