Baird Corporation

Inspex, Inc.

Hamamatsu Systems, Inc.

Charly D Allemand

Donald R Demers

Mario A Maldari

Hitoshi Iida

David L Brewer

Gary P Green

A method and apparatus for detecting particles on a surface of an object, such as a virgin or patterned semiconductor wafer, ceramic tile, or the like. In one embodiment, an apparatus is provided in which a scanning beam of laser light is brought to focus as an arcuate scan line on a surface of the object at a grazing angle of incidence using an off-axis hypertelecentric mirror. A pair of light detectors are positioned at a meridional angle of about 30 degrees and at an azimuthal angle of about 4 degrees to measure forward scattered light from the surface. The object is then moved translationally so that the beam can scan another line of the surface. A light trap is provided to trap light that is reflected by the surface, and a series of masks are provided to mask light which is scattered by the hypertelecentric mirror and, in the case of patterned objects, light which is diffracted by the pattern imprinted on the object.

Particle detection method and apparatus

An apparatus and method are disclosed for detecting the presence of particles on the surface of an object such as the front side of a patterned semiconductor wafer. A collimated beam of light is directed onto an area on the surface of the object at a grazing angle of incidence. A detector positioned above the surface detects light scattered from any particles which may be present on the surface, but not specularly reflected light. The output of the detector is fed into a computer where the information is processed and then displayed on a display. The surface is prepositioned relative to the incident light beam so that the diffracted light from the surface and the pattern on the surface is at a minimum. The object is then moved translationally to expose another area to the incident light beam so that the entire surface of the object or selected portions thereof can be examined, an area at a time.

An apparatus and method are disclosed for detecting the presence of particles on the surface of an object such as the front side of a patterned semiconductor wafer. A vertically expanded, horizontally scanning, beam of light is directed onto an area on the surface of the object at a grazing angle of incidence. A video camera positioned above the surface detects light scattered from any particles which may be present on the surface, but not specularly reflected light. The surface is angularly prepositioned (rotated) relative to the incident light beam so that the diffracted light from the surface and the pattern of lines on the surface is at a minimum. The object is then moved translationally to expose another area to the incident light beam so that the entire surface of the object or selected portions thereof can be examined, an area at a time.

An apparatus and method are disclosed for detecting the presence of particles on the surface of a material, such as a semiconductor wafer, using the principle of scattered light. Light from a mercury arc lamp is collimated by a Cassegrain mirror collimator. The collimated beam of light is deflected by an annular shaped 45.degree. mirror toward a truncated annular shaped inverted parabolic mirror. Light striking the parabolic mirror is reflected outward in all directions as a converging beam of light toward a ring mirror. Light striking the ring mirror is reflected inward and strikes the surface from all directions at an angle of about 78.degree. to 86.degree. from normal incidence as a small spot. An objective lens located a distance directly above the area on the surface illuminated by the spot of light and mounted at one end of a light tight tube collects light scattered by any particles on the surface, but not light reflected by the surface, and forms an image of the light so collected on the light sensitive surface of a photodetector mounted at the other end of the tube. The wafer is mounted on a holder which is movable rotationally and translationally relative to the impinging light beam so that the entire surface of the wafer may be scanned by the light beam, an area at a time.

A fluorescence spectrometer for multielement analysis including a source for atomizing a dispersed sample along an axis and a plurality of energizers and detectors preferably arranged in pairs about the source, with each of the pairs designed for analyzing one element. Preferably, the source is an inductively coupled plasma. Means is provided for each of the pairs to view a different segment of the source along its axis, depending on the element to be analyzed. Preferably, such means includes: a source movable along its axis; fiber optics interposed between the energizers and the source and between the source and the detectors; and a movable optical element interposed between the energizers and the source and between the source and the detectors. The spectrometer further features a polychromator for use in lieu of matched optical filters in the detectors and demountable hollow cathode lamps as energizers.

Spectrometer

A monochromatic imaging apparatus comprising a pair of similar diffraction gratings, a pair of focusing lenses, a pair of collimating lenses, an entrance slit, an exit slit and an intermediate slit, and means for concurrently moving the two gratings; wherein a polychromatic source image is placed at the entrance slit, and a collimating lens collimates the light rays from the source image and projects the collimated rays onto the first diffraction grating thereby to disperse the rays. The dispersed rays are then focused by the first focusing lens onto the intermediate slit, and then collimated by the second collimating lens onto the second diffraction grating which thereupon recombines the dispersed light. The recombined rays are then focused by the second focusing lens onto the exit slit. The two gratings may be concurrently moved in opposite or similar directions about an axis in the grating ruling plane and at the centers thereof, and at similar angles, so that the angle of incidence at the first grating is equal to the angle of diffraction at the second grating. In this manner, a monochromatic image of the polychromatic source image will appear at the exit slit and be of a selected band of wavelengths of the visible or other spectrum dependent upon the angular position of the two gratings from zero order of diffraction.

Monochromatic imaging apparatus

A method and apparatus for detecting and measuring the number and sizes of impurities on the surface of a material, such as a semiconductor wafer, wherein high intensity collimated light is directed onto the surface, in the absence of any extraneous light, through a collimating mirror, and employing a point source, whereat the particles will scatter the light, and wherein the surface is viewed by a highly light sensitive TV camera which picks up the scattered light and displays same on a viewing screen. The intensity of scattered light will indicate the size of the particles when compared with a calibrated model. Advantageously, a broad range of light waves is employed and thus enables a range of sizes of particles to be detected by the light scattered thereby. Also, advantageously, with the use of ordinarily available equipment, the system can inspect wafer surfaces for particles having sizes as small as 0.3 microns. The system also enables detection and identification of moving particles as distinguished from stationary particles.

Growing community of inventors

Newton, MA, United States of America

Charly D Allemand