Simultaneous multi-spot inspection and imaging

Abstract

A compact and versatile multi-spot inspection imaging system employs an objective for focusing an array of radiation beams to a surface and a second reflective or refractive objective having a large numerical aperture for collecting scattered radiation from the array of illuminated spots. The scattered radiation from each illuminated spot is focused to a corresponding optical fiber channel so that information about a scattering may be conveyed to a corresponding detector in a remote detector array for processing. For patterned surface inspection, a cross-shaped filter is rotated along with the surface to reduce the effects of diffraction by Manhattan geometry. A spatial filter in the shape of an annular aperture may also be employed to reduce scattering from patterns such as arrays on the surface. In another embodiment, different portions of the same objective may be used for focusing the illumination beams onto the surface and for collecting the scattered radiation from the illuminated spots simultaneously. In another embodiment, a one-dimensional array of illumination beams are directed at an oblique angle to the surface to illuminate a line of illuminated spots at an angle to the plane of incidence. Radiation scattered from the spots are collected along directions perpendicular to the line of spots or in a double dark field configuration.

What is claimed is:  
     
         1 . A method for detecting anomalies of a surface, comprising: 
 focusing illumination beams of radiation to an array of spots on the surface by means of a first objective; and    imaging scattered radiation from said spots onto an array of receivers or detectors by means of a second objective, so that each receiver in the array detects scattered radiation from a corresponding spot, said second objective having a numerical aperture that is larger than that of the first objective    
     
     
         2 . The method of  claim 1 , wherein said imaging images by means of reflective or refractive optics.  
     
     
         3 . The method of  claim 1 , further comprising selecting a wavelength and supplying the illumination beams of radiation so that the radiation comprises a component of the selected wavelength in a UV, deep UV, visible or infrared wavelength range, said supplying comprising passing a beam of radiation of the selected wavelength component through a diffracting element to form the illumination beams.  
     
     
         4 . The method of  claim 3 , further comprising altering the selected wavelength of the wavelength component of the illumination beams focused in the focusing, and replacing the diffracting element by another diffracting element so that spot separation of the said spots remain substantially unchanged by the altering.  
     
     
         5 . The method of  claim 1 , wherein said imaging images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         6 . The method of  claim 1 , wherein the focusing focuses the beams to a one or two dimensional array of spots, said method further comprising causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         7 . The method of  claim 6 , wherein the causing causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         8 . The method of  claim 1 , wherein the focusing focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         9 . The method of  claim 1 , wherein the focusing comprises focusing the beams to substantially circular spots on the surface.  
     
     
         10 . The method of  claim 1 , wherein the focusing comprises focusing the beams to the surface in directions that are substantially normal to the surface.  
     
     
         11 . The method of  claim 1 , wherein the focusing comprises focusing the beams to a patterned semiconductor wafer.  
     
     
         12 . The method of  claim 1 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the focusing comprises focusing the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         13 . The method of  claim 1 , wherein said imaging images scattered radiation by means of optics that has an axis in a direction at or near a normal direction to the surface.  
     
     
         14 . The method of  claim 1 , further comprising passing a beam of radiation through a diffraction element to obtain the illumination beams.  
     
     
         15 . A apparatus for detecting anomalies of a surface, comprising: 
 illumination optics that focuses illumination beams of radiation to an array of spots on the surface, said illumination optics comprising a first objective; and    imaging optics that images scattered radiation from said spots onto an array of receivers or detectors so that each receiver in the array detects scattered radiation from a corresponding spot, said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.    
     
     
         16 . The apparatus of  claim 15 , wherein said second objective comprises a reflective surface or a refractive element.  
     
     
         17 . The apparatus of  claim 15 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         18 . The apparatus of  claim 17 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         19 . The apparatus of  claim 15 , wherein said imaging optics images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         20 . The apparatus of  claim 15 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion about a rotational axis between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         21 . The apparatus of  claim 20 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         22  The apparatus of  claim 20 , wherein the imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         23 . The apparatus of  claim 15 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or {fraction (3/4)} of the predetermined spot size.  
     
     
         24 . The apparatus of  claim 15 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         25 . The apparatus of  claim 15 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         26 . The apparatus of  claim 15 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         27 . The apparatus of  claim 15 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         28 . The apparatus of  claim 15 , wherein said second objective has an axis in a direction at or near a normal direction to the surface.  
     
     
         29 . The apparatus of  claim 15 , wherein said first objective has a numerical aperture not more than about 0.8.  
     
     
         30 . The apparatus of  claim 15 , further comprising the array of receivers or detectors.  
     
     
         31 . The apparatus of  claim 30 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         32 . The apparatus of  claim 15 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the receivers or detectors.  
     
     
         33 . A method for detecting anomalies of a surface, comprising: 
 focusing illumination beams of radiation to an array of spots on the surface;    imaging radiation reflected from said spots onto a first array of receivers or detectors so that each receiver in the first array receives radiation from a corresponding spot in the array of spots; and    imaging scattered radiation from said spots onto a second array of receivers or detectors in a dark field imaging scheme so that each receiver or detector in the second array receives radiation from a corresponding spot.    
     
     
         34 . The method of  claim 33 , wherein said scattered radiation from said spots is imaged in the dark field imaging scheme by means of reflective optics.  
     
     
         35 . The method of  claim 33 , further comprising selecting a wavelength and supplying the illumination beams of radiation so that the radiation comprises a component of the selected wavelength in a UV, deep UV, visible or infrared wavelength range, said supplying comprising passing a beam of radiation of the selected wavelength component through a diffracting element to form the illumination beams.  
     
     
         36 . The method of  claim 35 , further comprising altering the selected wavelength of the wavelength component of the illumination beams focused in the focusing, and replacing the diffracting element by another diffracting element so that spot separation of the said spots remain substantially unchanged by the altering.  
     
     
         37 . The method of  claim 33 , wherein the focusing employs a first objective, and said imaging in the dark field imaging scheme images scattered radiation from said spots onto the array of receivers or detectors by means of a second objective having a numerical aperture different from that of the first objective and without employing the first objective.  
     
     
         38 . The method of  claim 33 , wherein the focusing focuses the beams to a one or two dimensional array of spots, said method further comprising causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         39 . The method of  claim 38 , wherein the causing causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         40 . The method of  claim 33 , wherein the focusing focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¼ of the predetermined spot size.  
     
     
         41 . The method of  claim 33 , wherein the focusing comprises focusing the beams to substantially circular spots on the surface.  
     
     
         42 . The method of  claim 33 , wherein the focusing comprises focusing the beams to the surface in directions that are substantially normal to the surface.  
     
     
         43 . The method of  claim 33 , wherein the focusing comprises focusing the beams to a patterned semiconductor wafer.  
     
     
         44 . The method of  claim 33 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the focusing comprises focusing the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         45 . The method of  claim 33 , wherein said imaging in the dark field imaging scheme images scattered radiation by means of optics that has an axis in a direction at or near a normal direction to the surface.  
     
     
         46 . An apparatus for detecting anomalies of a surface, comprising: 
 illumination optics focusing illumination beams of radiation to an array of spots on the surface;    bright field imaging optics imaging radiation reflected from said spots onto a first array of receivers or detectors so that each receiver in the first array receives radiation from a corresponding spot in the array of spots; and    dark field imaging optics imaging scattered radiation from said spots onto a second array of receivers or detectors so that each receiver or detector in the second array receives radiation from a corresponding spot.    
     
     
         47 . The apparatus of  claim 46 , wherein said dark field imaging optics comprises a curved reflective surface.  
     
     
         48 . The apparatus of  claim 46 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         49 . The apparatus of  claim 48 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         50 . The apparatus of  claim 46 , said illumination optics comprising a first objective, said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.  
     
     
         51 . The apparatus of  claim 50 , wherein said dark field imaging optics images scattered radiation from said spots onto the second array of receivers or detectors without employing the first objective.  
     
     
         52 . The apparatus of  claim 46 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         53 . The apparatus of  claim 52 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         54  The apparatus of  claim 52 , wherein the dark field imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         55 . The apparatus of  claim 46 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         56 . The apparatus of  claim 46 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         57 . The apparatus of  claim 46 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         58 . The apparatus of  claim 46 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         59 . The apparatus of  claim 46 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         60 . The apparatus of  claim 46 , wherein said dark field imaging optics comprises a second objective having an axis in a direction at or near a normal direction to the surface.  
     
     
         61 . The apparatus of  claim 46 , said illumination optics comprising an objective with a numerical aperture not more than about 0.8.  
     
     
         62 . The apparatus of  claim 46 , further comprising the first and second array of receivers or detectors.  
     
     
         63 . The apparatus of  claim 46 , wherein the first array of receivers comprises an array of optical fibers.  
     
     
         64 . The apparatus of  claim 46 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the dark field imaging optics to block specular reflections of the beams from the surface from reaching the second array of receivers or detectors.  
     
     
         65 . A method for detecting anomalies of a surface, comprising: 
 focusing illumination beams of radiation to an array of spots on the surface by means of a first objective, wherein radiation of illumination beams comprises at least one wavelength component in the UV or deep UV range of wavelengths; and    imaging scattered radiation from said spots onto an array of receivers or detectors by means of optics that comprises a reflective second objective, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots.    
     
     
         66 . The method of  claim 65 , further comprising: 
 selecting a wavelength from the UV, deep UV visible or infrared wavelength range; and passing a beam of radiation of the selected wavelength component through a diffracting element to form the illumination beams.    
     
     
         67 . The method of  claim 66 , further comprising: 
 altering the selected wavelength of the wavelength component of the illumination beams focused in the focusing; and    replacing the diffracting element by another diffracting element so that spot separation of the said spots remain substantially unchanged by the altering.    
     
     
         68 . The method of  claim 65 , wherein said imaging images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         69 . The method of  claim 65 , wherein the focusing focuses the beams to a one or two dimensional array of spots, said method further comprising causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         70 . The method of  claim 69 , wherein the causing causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         71 . The method of  claim 65 , wherein the focusing focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¼ of the predetermined spot size.  
     
     
         72 . The method of  claim 65 , wherein the focusing comprises focusing the beams to substantially circular spots on the surface.  
     
     
         73 . The method of  claim 65 , wherein the focusing comprises focusing the beams to the surface in directions that are substantially normal to the surface.  
     
     
         74 . The method of  claim 65 , wherein the focusing comprises focusing the beams to a patterned semiconductor wafer.  
     
     
         75 . The method of  claim 65 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the focusing comprises focusing the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         76 . The method of  claim 65 , wherein said imaging images scattered radiation by means of optics that has an axis in a direction at or near a normal direction to the surface.  
     
     
         77 . A apparatus for detecting anomalies of a surface, comprising: 
 illumination optics comprising a first objective that focuses illumination beams of radiation to an array of spots on the surface, wherein radiation of illumination beams comprises at least one wavelength component in the UV or deep UV range of wavelengths; and    imaging optics that images scattered radiation from said spots onto an array of receivers or detectors, said imaging optics comprising a reflective second objective, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots.    
     
     
         78 . The apparatus of  claim 77 , wherein said second objective has a numerical aperture that is larger than that of the first objective.  
     
     
         79 . The apparatus of  claim 77 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         80 . The apparatus of  claim 79 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         81 . The apparatus of  claim 77 , wherein said imaging optics images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         82 . The apparatus of  claim 77 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         83 . The apparatus of  claim 82 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         84  The apparatus of  claim 82 , wherein the imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         85 . The apparatus of  claim 77 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         86 . The apparatus of  claim 77 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         87 . The apparatus of  claim 77 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         88 . The apparatus of  claim 77 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         89 . The apparatus of  claim 77 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         90 . The apparatus of  claim 77 , wherein said second objective has an axis in a direction at or near a normal direction to the surface.  
     
     
         91 . The apparatus of  claim 77 , wherein said first objective has a numerical aperture not more than about 0.8.  
     
     
         92 . The apparatus of  claim 77 , further comprising the array of receivers or detectors.  
     
     
         93 . The apparatus of  claim 92 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         94 . The apparatus of  claim 77 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the receivers or detectors.  
     
     
         95 . An optical head for use in detecting anomalies of a surface, comprising: 
 illumination optics focusing illumination beams of radiation to an array of spots on the surface;    an array of optical fibers; and    imaging optics imaging scattered radiation from said spots onto the array of optical fibers, so that each optical fiber receives scattered radiation from a corresponding spot in the array of spots.    
     
     
         96 . The optical head of  claim 95 , said illumination optics comprising a first objective and said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.  
     
     
         97 . The optical head of  claim 96 , wherein said imaging optics images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         98 . The optical head of  claim 95 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         99 . The optical head of  claim 98 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         100 . The optical head of  claim 95 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said optical head further comprising an instrument causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         101 . The optical head of  claim 100 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         102 . The optical head of  claim 100 , wherein the imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         103 . The optical head of  claim 95 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or {fraction (3/4)} of the predetermined spot size.  
     
     
         104 . The optical head of  claim 95 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         105 . The optical head of  claim 95 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         106 . The optical head of  claim 95 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         107 . The optical head of  claim 95 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         108 . The optical head of  claim 95 , said imaging optics comprising a second objective that has an axis in a direction at or near a normal direction to the surface.  
     
     
         109 . The optical head of  claim 95 , said illumination optics comprising a first objective that has a numerical aperture not more than about 0.8.  
     
     
         110 . The optical head of  claim 95 , further comprising the array of receivers or detectors.  
     
     
         111 . The optical head of  claim 110 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         112 . The optical head of  claim 95 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the receivers or detectors.  
     
     
         113 . An apparatus detecting anomalies of a surface of a semiconductor sample having multiple dice thereon, comprising: 
 (a) an optical head comprising: 
 illumination optics focusing illumination beams of radiation to a one or two dimensional array of spots on the surface by means of a first objective;  
 an array of receivers;  
 imaging optics imaging scattered radiation from said spots onto the array of receivers, so that each receiver receives scattered radiation from a corresponding spot in the array of spots;  
   (b) a plurality of detectors, each detector generating a signal in response to scattered radiation in one of the receivers in the array of receivers;    (c) an instrument causing rotational motion between the surface and the illumination beams about a rotational axis so that the beams scan over substantially entire area of the surface; and    (d) a storage storing the signals from the detectors as the beams scan over the surface thereby storing signals generated in response to scattered radiation from at least two dice of the surface.    
     
     
         114 . The apparatus of  claim 113 , wherein the storage stores the signals from the detectors as the beams scan over the surface thereby storing signals generated in response to scattered radiation from an annular region containing at least two adjacent dice of the surface.  
     
     
         115 . The apparatus of  claim 113 , said illumination optics comprising a first objective and said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.  
     
     
         116 . The apparatus of  claim 113 , further comprising means for supplying a beam of radiation 0of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         117 . The apparatus of  claim 116 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         118 . The apparatus of  claim 113 , said illumination optics comprising a first objective and wherein said imaging optics images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         119 . The apparatus of  claim 113 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         120 . The apparatus of  claim 119 , wherein the imaging optics is substantially rotationally symmetric about a rotational axis of the rotational motion.  
     
     
         121 . The apparatus of  claim 113 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         122 . The apparatus of  claim 113 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         123 . The apparatus of  claim 113 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         124 . The apparatus of  claim 113 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         125 . The apparatus of  claim 113 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         126 . The apparatus of  claim 113 , said imaging optics comprising an objective having an axis in a direction at or near a normal direction to the surface.  
     
     
         127 . The apparatus of claim  1113 , said illumination optics comprising an objective that has a numerical aperture not more than about 0.8.  
     
     
         128 . The apparatus of  claim 113 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         129 . The apparatus of claim  1113 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the receivers or detectors.  
     
     
         130 . The apparatus method of  claim 113 , wherein the storage stores the signals from the detectors as the beams scan over the entire surface thereby storing signals generated in response to scattered radiation from substantially the entire surface.  
     
     
         131 . The apparatus of  claim 113 , further comprising a processor comparing signals generated in response to scattered radiation from the at least two dice of the surface to detect anomalies.  
     
     
         132 . A method detecting anomalies of a surface of a semiconductor sample having multiple dice thereon, comprising: 
 focusing illumination beams of radiation to a one or two dimensional array of spots on the surface by means of a first objective;    imaging scattered radiation from said spots onto the array of receivers or detectors, so that each receiver or detector receives scattered radiation from a corresponding spot in the array of spots;    generating signals in response to scattered radiation received by the receivers or detectors in the array of receivers or detectors;    causing rotational motion between the surface and the illumination beams about a rotational axis so that the beams scan over substantially entire area of the surface; and    storing the signals from the detectors as the beams scan over the surface thereby storing signals generated in response to scattered radiation from at least two dice of the surface.    
     
     
         133 . The method of  claim 132 , wherein the storing stores the signals from the detectors as the beams scan over the surface thereby storing signals generated in response to scattered radiation from an annular region containing at least two adjacent dice of the surface.  
     
     
         134 . The method of  claim 132 , wherein the storing stores the signals from the detectors as the beams scan over the surface thereby storing signals generated in response to scattered radiation from an annular region containing at least two adjacent dice of the surface, said method further comprising forming a pixel map of the surface from said stored signals.  
     
     
         135 . The method of  claim 132 , further comprising comparing signals generated in response to scattered radiation from the at least two dice of the surface to detect anomalies.  
     
     
         136 . A method for detecting anomalies of a surface with a diffracting pattern thereon, comprising: 
 focusing illumination beams of radiation to an array of spots on the surface;    imaging scattered radiation from said spots onto an array of receivers or detectors, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots;    causing relative rotational motion between the surface and the illumination beams so that the beams scan over an area of the surface; and    wherein said imaging comprises causing scattered radiation from the array of spots to be passed to the array of receivers or detectors by means of a filter having an aperture that moves substantially in synchronism with the rotational motion to reduce diffraction from the pattern that is passed to the array of receivers or detectors as a result of the relative rotational motion between the pattern and the beams.    
     
     
         137 . The method of  claim 136 , wherein said scattered radiation from said spots is imaged by means of reflective optics.  
     
     
         138 . The method of  claim 136 , further comprising selecting a wavelength and supplying the illumination beams of radiation so that the radiation comprises a component of the selected wavelength in a UV, deep UV, visible or infrared wavelength range, said supplying comprising passing a beam of radiation of the selected wavelength component through a diffracting element to form the illumination beams.  
     
     
         139 . The method of  claim 138 , further comprising altering the selected wavelength of the wavelength component of the illumination beams focused in the focusing, and replacing the diffracting element by another diffracting element so that spot separation of the said spots remain substantially unchanged by the altering.  
     
     
         140 . The method of  claim 136 , wherein the focusing employs a first objective, and said imaging images scattered radiation from said spots onto the array of receivers or detectors by means of a second objective having a numerical aperture different from that of the first objective and without employing the first objective.  
     
     
         141 . The method of  claim 136 , wherein the focusing focuses the beams to a one or two dimensional array of spots, said method further comprising causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         142 . The method of  claim 141 , wherein the causing causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         143 . The method of  claim 136 , wherein the focusing focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¼ of the predetermined spot size.  
     
     
         144 . The method of  claim 136 , wherein the focusing comprises focusing the beams to substantially circular spots on the surface.  
     
     
         145 . The method of  claim 136 , wherein the focusing comprises focusing the beams to the surface in directions that are substantially normal to the surface.  
     
     
         146 . The method of  claim 136 , wherein the focusing comprises focusing the beams to a patterned semiconductor wafer.  
     
     
         147 . The method of  claim 136 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the focusing comprises focusing the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         148 . The method of  claim 136 , wherein said imaging images scattered radiation by means of optics that has an axis in a direction at or near a normal direction to the surface.  
     
     
         149 . An apparatus for detecting anomalies of a surface, comprising: 
 illumination optics focusing illumination beams of radiation to an array of spots on the surface;    imaging optics imaging scattered radiation from said spots onto an array of receivers or detectors, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots;    an instrument causing relative rotational motion between the surface and the illumination beams so that the beams scan over an area of the surface;    a filter; and    a device that moves the filter;    wherein said imaging optics causes scattered radiation from the array of spots to be passed to the array of receivers or detectors by means of the filter having an aperture that is moved by the device substantially in synchronism with the relative rotational motion to reduce diffraction from the pattern that is passed to the array of receivers or detectors as a result of the relative rotational motion between the pattern and the beams.    
     
     
         150 . The apparatus of  claim 149 , wherein said imaging optics comprises a curved reflective surface.  
     
     
         151 . The apparatus of  claim 149 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         152 . The apparatus of  claim 151 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         153 . The apparatus of  claim 149 , said illumination optics comprising a first objective, said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.  
     
     
         154 . The apparatus of  claim 153 , wherein said imaging optics images scattered radiation from said spots onto the second array of receivers or detectors without employing the first objective.  
     
     
         155 . The apparatus of  claim 149 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         156 . The apparatus of  claim 155 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         157  The apparatus of  claim 155 , wherein the imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         158 . The apparatus of  claim 149 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         159 . The apparatus of  claim 149 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         160 . The apparatus of  claim 149 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         161 . The apparatus of  claim 149 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         162 . The apparatus of  claim 149 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         163 . The apparatus of  claim 149 , wherein said imaging optics comprises a second objective having an axis in a direction at or near a normal direction to the surface.  
     
     
         164 . The apparatus of  claim 149 , said illumination optics comprising an objective with a numerical aperture not more than about 0.8.  
     
     
         165 . The apparatus of  claim 149 , further comprising the first and second array of receivers or detectors.  
     
     
         166 . The apparatus of  claim 165 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         167 . The apparatus of  claim 149 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the second array of receivers or detectors.  
     
     
         168 . The apparatus of  claim 149 , said filter comprising a spatial filter comprising a strip of material in the shape of across.  
     
     
         169 . The apparatus of  claim 168 , said material being opaque, scattering or reflective with respect to radiation.  
     
     
         170 . A method for detecting anomalies of a surface with a diffracting pattern thereon, comprising: 
 focusing illumination beams of radiation to an array of illuminated elongated spots on the surface at oblique angle(s) of incidence to the surface, said spots arranged along a substantially straight line;    imaging scattered radiation from said spots onto an array of receivers or detectors by means of imaging optics with a focal plane that substantially contains all of the spots, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots.    
     
     
         171 . The method of  claim 170 , wherein said focusing focuses the beams so that the substantially straight line is at about 45 degrees to a plane of incidence of the beams.  
     
     
         172 . The method of  claim 170 , wherein said imaging images the scattered radiation along one or more directions that are substantially normal to the straight line.  
     
     
         173 . The method of  claim 170 , wherein said imaging images the scattered radiation along one or more directions that are substantially normal to the plane of incidence of the beams.  
     
     
         174 . The method of  claim 170 , wherein the scattered radiation from said spots is imaged by means of reflective optics.  
     
     
         175 . The method of  claim 170 , further comprising selecting a wavelength and supplying the illumination beams of radiation so that the radiation comprises a component of the selected wavelength in a UV, deep UV, visible or infrared wavelength range, said supplying comprising passing a beam of radiation of the selected wavelength component through a diffracting element to form the illumination beams.  
     
     
         176 . The method of  claim 175 , further comprising altering the selected wavelength of the wavelength component of the illumination beams focused in the focusing, and replacing the diffracting element by another diffracting element so that spot separation of the said spots remain substantially unchanged by the altering.  
     
     
         177 . The method of  claim 170 , wherein the focusing focuses the beams to a one or two dimensional array of spots, said method further comprising causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         178 . The method of  claim 177 , wherein the causing causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         179 . The method of  claim 177 , wherein the focusing focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         180 . The method of  claim 170 , wherein the focusing comprises focusing the beams to substantially circular spots on the surface.  
     
     
         181 . The method of  claim 170 , wherein the focusing comprises focusing the beams to a patterned semiconductor wafer.  
     
     
         182 . The method of  claim 170 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the focusing comprises focusing the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         183 . The method of  claim 170 , wherein said focusing focuses polarized radiation, and said imaging comprises passing the scattered radiation through a polarizer.  
     
     
         184 . An apparatus for detecting anomalies of a surface, comprising: 
 illumination optics focusing illumination beams of radiation to an array of illuminated elongated spots on the surface at oblique angle(s) of incidence to the surface, said spots arranged along a substantially straight line;    imaging optics imaging scattered radiation from said spots onto an array of receivers or detectors, said imaging optics having a focal plane that substantially contains all of the spots, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots.    
     
     
         185 . The apparatus of  claim 184 , wherein said imaging optics comprises a curved reflective surface.  
     
     
         186 . The apparatus of  claim 184 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         187 . The apparatus of  claim 186 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         188 . The apparatus of  claim 184  said illumination optics comprising a first objective, said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.  
     
     
         189 . The apparatus of  claim 188 , wherein said imaging optics images scattered radiation from said spots onto the array of receivers or detectors without employing the first objective.  
     
     
         190 . The apparatus of  claim 184 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         191 . The apparatus of  claim 190 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         192 . The apparatus of  claim 190 , wherein the imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         193 . The apparatus of  claim 184 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         194 . The apparatus of  claim 184 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         195 . The apparatus of  claim 184 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         196 . The apparatus of  claim 184 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         197 . The apparatus of  claim 184 , said illumination optics comprising an objective with a numerical aperture not more than about 0.8.  
     
     
         198 . The apparatus of  claim 184 , further comprising the array of receivers or detectors.  
     
     
         199 . The apparatus of  claim 198 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         200 . The apparatus of  claim 184 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the array of receivers or detectors.  
     
     
         201 . The apparatus of  claim 184 , wherein said illumination optics focuses the beams so that the substantially straight line is at about 45 degrees to a plane of incidence of the beams.  
     
     
         202 . The apparatus of  claim 184 , wherein said imaging optics images the scattered radiation along one or more directions that are substantially normal to the substantially straight line.  
     
     
         203 . The apparatus of  claim 202 , wherein said imaging optics comprises two sets of objectives, each of said sets of objectives imaging the scattered radiation along directions that are on opposite sides of the substantially straight line.  
     
     
         204 . The apparatus of  claim 184 , wherein said imaging optics comprises a first and a second set of objectives, said first set of objectives imaging the scattered radiation along forward scattering directions with respect to the illumination beams, and said second set of objectives imaging the scattered radiation along back scattering directions with respect to the illumination beams.  
     
     
         205 . The apparatus of  claim 184 , wherein said illumination optics focuses polarized radiation, and said imaging optics comprises a polarizer.  
     
     
         206 . The apparatus of  claim 184 , wherein said imaging optics images the scattered radiation in at least one direction that is substantially at 90 degrees azimuthal angle relative to the illumination beams as they reach the surface.  
     
     
         207 . The apparatus of  claim 184 , wherein said imaging optics images the scattered radiation in at least one direction that is substantially normal to the surface.  
     
     
         208 . A apparatus for detecting anomalies of a surface, comprising: 
 a source providing illumination beams of radiation;    optics that focuses the illumination beams of radiation to an array of spots on the surface, said illumination optics having an aperture, wherein the illumination beams of radiation are focused to an array of spots through only a first portion of the aperture; and    an array of receivers or detectors;    wherein the optics images scattered radiation from said spots onto the array of receivers or detectors so that each receiver in the array detects scattered radiation from a corresponding spot, said imaging occurring through a second portion of the aperture that is different from the first portion.    
     
     
         209 . The apparatus of  claim 208 , wherein the second portion of the aperture is larger than the first portion.  
     
     
         210 . The apparatus of  claim 208 , said source comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beams.  
     
     
         211 . The apparatus of  claim 210 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         212 . The apparatus of  claim 208 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion about a rotational axis between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         213 . The apparatus of  claim 212 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         214 . The apparatus of  claim 213 , wherein the optics is substantially rotationally symmetric about the rotational axis.  
     
     
         215 . The apparatus of  claim 208 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         216 . The apparatus of  claim 208 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         217 . The apparatus of  claim 208 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         218 . The apparatus of  claim 208 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         219 . The apparatus of  claim 208 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         220 . The apparatus of  claim 208 , wherein said optics has an axis in a direction at or near a normal direction to the surface.  
     
     
         221 . The apparatus of  claim 208 , wherein said optics has a numerical aperture not more than about 0.8.  
     
     
         222 . The apparatus of  claim 208 , further comprising the array of receivers or detectors.  
     
     
         223 . The apparatus of  claim 222 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         224 . A method for detecting anomalies of a surface with a diffracting pattern thereon, comprising: 
 focusing illumination beams of radiation to an array of spots on the surface;    imaging scattered radiation from said spots onto an array of receivers or detectors, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots;    causing relative rotational motion between the surface and the illumination beams so that the beams scan over an area of the surface; and    wherein said imaging comprises causing scattered radiation from the array of spots to be passed to the array of receivers or detectors by means of a filter having an annular aperture to reduce diffraction from the pattern that is passed to the array of receivers or detectors as a result of the relative rotational motion between the pattern and the beams.    
     
     
         225 . The method of  claim 224 , wherein said scattered radiation from said spots is imaged by means of reflective optics.  
     
     
         226 . The method of  claim 224 , further comprising selecting a wavelength and supplying the illumination beams of radiation so that the radiation comprises a component of the selected wavelength in a UV, deep UV, visible or infrared wavelength range, said supplying comprising passing a beam of radiation of the selected wavelength component through a diffracting element to form the illumination beams.  
     
     
         227 . The method of  claim 226 , further comprising altering the selected wavelength of the wavelength component of the illumination beams focused in the focusing, and replacing the diffracting element by another diffracting element so that spot separation of the said spots remain substantially unchanged by the altering.  
     
     
         228 . The method of  claim 224 , wherein the focusing employs a first objective, and said imaging images scattered radiation from said spots onto the array of receivers or detectors by means of a second objective having a numerical aperture different from that of the first objective and without employing the first objective.  
     
     
         229 . The method of  claim 224 , wherein the focusing focuses the beams to a one or two dimensional array of spots, said method further comprising causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         230 . The method of  claim 224 , wherein the causing causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         231 . The method of  claim 224 , wherein the focusing focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¼ of the predetermined spot size.  
     
     
         232 . The method of  claim 224 , wherein the focusing comprises focusing the beams to substantially circular spots on the surface.  
     
     
         233 . The method of  claim 224 , wherein the focusing comprises focusing the beams to the surface in directions that are substantially normal to the surface.  
     
     
         234 . The method of  claim 224 , wherein the focusing comprises focusing the beams to a patterned semiconductor wafer.  
     
     
         235 . The method of  claim 224 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the focusing comprises focusing the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         236 . The method of  claim 224 , wherein said imaging images scattered radiation by means of optics that has an axis in a direction at or near a normal direction to the surface.  
     
     
         237 . An apparatus for detecting anomalies of a surface, comprising: 
 illumination optics focusing illumination beams of radiation to an array of spots on the surface;    imaging optics imaging scattered radiation from said spots onto an array of receivers or detectors, so that each receiver or detector in the array receives scattered radiation from a corresponding spot in the array of spots;    an instrument causing relative rotational motion between the surface and the illumination beams so that the beams scan over an area of the surface;    a filter; and    a device that moves the filter;    wherein said imaging optics causes scattered radiation from the array of spots to be passed to the array of receivers or detectors by means of the filter having an aperture that is substantially annular in shape to reduce diffraction from the pattern that is passed to the array of receivers or detectors as a result of the relative rotational motion between the pattern and the beams.    
     
     
         238 . The apparatus of  claim 237 , wherein said imaging optics comprises a curved reflective surface.  
     
     
         239 . The apparatus of  claim 237 , further comprising means for supplying a beam of radiation of a selected wavelength in a UV, deep UV, visible or infrared wavelength range, and a diffracting element that diffracts the beam of radiation of the selected wavelength component to form the illumination beans.  
     
     
         240 . The apparatus of  claim 239 , said supplying means comprising an optical source that supplies radiation of a wavelength selectable from a plurality of wavelengths, said apparatus comprising a plurality of diffracting elements, each element designed to diffract radiation at one of the plurality of wavelengths so that spot separation of the spots remains substantially unchanged when the source selects and supplies radiation substantially at a different one of the plurality of wavelengths than previously.  
     
     
         241 . The apparatus of  claim 237 , said illumination optics comprising a first objective, said imaging optics comprising a second objective having a numerical aperture that is larger than that of the first objective.  
     
     
         242 . The apparatus of  claim 241 , wherein said imaging optics images scattered radiation from said spots onto the second array of receivers or detectors without employing the first objective.  
     
     
         243 . The apparatus of  claim 237 , wherein the illumination optics focuses the beams to a one or two dimensional array of spots, said apparatus further comprising an instrument causing rotational motion between the surface and the beams so that the spots scan over overlapping paths.  
     
     
         244 . The apparatus of  claim 243 , wherein the instrument causes rotational motion of the surface while leaving the beams at substantially stationary positions.  
     
     
         245 . The apparatus of  claim 243 , wherein the imaging optics is substantially rotationally symmetric about the rotational axis.  
     
     
         246 . The apparatus of  claim 237 , wherein the illumination optics focuses the beams to a two dimensional array of spots of a predetermined spot size, and so that adjacent spots are spaced apart by a spacing such that the overlapping paths of adjacent spots overlap by about ⅔ or ¾ of the predetermined spot size.  
     
     
         247 . The apparatus of  claim 237 , wherein the illumination optics focuses the beams to substantially circular spots on the surface.  
     
     
         248 . The apparatus of  claim 237 , wherein the illumination optics focuses the beams to the surface in directions that are substantially normal to the surface.  
     
     
         249 . The apparatus of  claim 237 , wherein the illumination optics focuses the beams to a patterned semiconductor wafer.  
     
     
         250 . The apparatus of  claim 237 , said surface comprising a surface of an unpatterned semiconductor wafer, wherein the illumination optics focuses the beams to the surface in directions that are oblique to the surface and so that at least one dimension of the spots is not less than about 5 microns.  
     
     
         251 . The apparatus of  claim 237 , wherein said imaging optics comprises a second objective having an axis in a direction at or near a normal direction to the surface.  
     
     
         252 . The apparatus of  claim 237 , said illumination optics comprising an objective with a numerical aperture not more than about 0.8.  
     
     
         253 . The apparatus of  claim 237 , further comprising the first and second array of receivers or detectors.  
     
     
         254 . The apparatus of  claim 253 , wherein the array of receivers comprises an array of optical fibers.  
     
     
         255 . The apparatus of  claim 237 , said illumination optics comprising a reflective surface reflecting the beams to the surface, said reflective surface located in a collection path of the imaging optics to block specular reflections of the beams from the surface from reaching the second array of receivers or detectors.  
     
     
         256 . The apparatus of  claim 237 , said annular aperture being between about 5 to 9° from a normal direction to the surface.  
     
     
         257 . The apparatus of  claim 237 , said filter being substantially stationary when relative rotational motion between the surface and the illumination beams is caused.