Automatic holographic wafer positioning system and method

Claim 1

A method of providing reference regions for alignment of a semiconductor wafer having spaced regions therein comprising: forming by techniques employed during the fabrication of said wafer a separate reference pattern in at least two spaced regions in said wafer, and forming each of said patterns so that it: a. has a spatial frequency content distinct from the potions of said wafer outside said regions, and b. defines an alignment pattern consisting of a planar figure of rotation contained within the plane of said wafer.

Claim 2

A method of providing reference regions for alignment of a semiconductor wafer having spaced regions therein comprising: forming by techniques employed during the fabrication of said wafer a separate reference pattern in at least two spaced regions in said wafer, and forming each of said patterns so that it: a. has a spatial frequency content distinct from the potions of said wafer outside said regions, and b. defines an alignment pattern consisting of a planar figure of rotation contained within the plane of said wafer.

Claim 7

A method of orienting a semiconductor wafer having spaced regions therein and provided, by techniques employed during the fabrication of said wafer, with a separate reference pattern in at least two spaced regions in said wafer, the patterns having a spatial frequency content distinct from the portions of said wafer outside said regions and defining identical full planar figures of rotation, comprising: a. providing a complex spatial filter representing said figure of rotation and responsive to light of a preselected wavelength, b. directing a beam of coherent monochromatic light of said wavelength through said wafer and said filter to form an image plane at least two recognition spots of light whose positions in said image plane relative to respective reference positions are dependent upon the relative degree of alignment of said wafer and said filter, c. producing error signals respectively indicative of the relative displacement between each of said recognition spots and its associated reference position, and d. controlling in response to said error signals the respective position of said wafer to reduce said relative displacement.

Claim 8

A method of orienting a semiconductor wafer having spaced regions therein and provided, by techniques employed during the fabrication of said wafer, with a separate reference pattern in at least two spaced regions in said wafer, the patterns having a spatial frequency content distinct from the portions of said wafer outside said regions and defining identical full planar figures of rotation, comprising: a. providing a complex spatial filter representing said figure of rotation and responsive to light of a preselected wavelength, b. directing a beam of coherent monochromatic light of said wavelength through said wafer and said filter to form an image plane at least two recognition spots of light whose positions in said image plane relative to respective reference positions are dependent upon the relative degree of alignment of said wafer and said filter, c. producing error signals respectively indicative of the relative displacement between each of said recognition spots and its associated reference position, and d. controlling in response to said error signals the respective position of said wafer to reduce said relative displacement.

Claim 9

A system for orienting a piece of semiconductor material with respect to a photomask comprising: a. a source of monochromatic infrared light, b. a plurality of regions on said piece having a pattern of transmission of light corresponding to a full planar figure of rotation, c. means for directing said light through said regions, d. a complex spatial filter of said figure of rotation in a frequency plane, e. means for distributing said light directed through said regions into said frequency plane in a pattern corresponding to the Fourier transform of said figure of rotation, f. means responsive to the correlation between said light directed into said frequency lane and said spatial filter for generating a plurality of recognition spots in an image plane, the displacement of said recognition spots from respective points of alignment of said piece of said filter, g. means responsive to the displacement of said spots from alignment for generating error signals, h. means responsive to said error signals for reducing said displacement from alignment of said piece and said filter, and i. means for maintaining said photomask and said filter in fixed spatial relationship, whereby alignment of said piece with said filter thereby aligns said piece with said photomask.

Claim 10

A system for orienting a piece of semiconductor material with respect to a photomask comprising: a. a source of monochromatic infrared light, b. a plurality of regions on said piece having a pattern of transmission of light corresponding to a full planar figure of rotation, c. means for directing said light through said regions, d. a complex spatial filter of said figure of rotation in a frequency plane, e. means for distributing said light directed through said regions into said frequency plane in a pattern corresponding to the Fourier transform of said figure of rotation, f. means responsive to the correlation between said light directed into said frequency lane and said spatial filter for generating a plurality of recognition spots in an image plane, the displacement of said recognition spots from respective points of alignment of said piece of said filter, g. means responsive to the displacement of said spots from alignment for generating error signals, h. means responsive to said error signals for reducing said displacement from alignment of said piece and said filter, and i. means for maintaining said photomask and said filter in fixed spatial relationship, whereby alignment of said piece with said filter thereby aligns said piece with said photomask.

Claim 11

A method of providing reference regions in a transparent workpiece having spaced regions therein comprising forming by techniques employed during the fabrication of said workpiece a separate reference pattern in at least two spaced regions in said workpiece, and forming each of said patterns so that it: a. has a spatial frequency content distinct from the portions of said workpiece outside said regions, and b. defines a full planar figure of rotation.

Claim 12

A method of providing reference regions in a transparent workpiece having spaced regions therein comprising forming by techniques employed during the fabrication of said workpiece a separate reference pattern in at least two spaced regions in said workpiece, and forming each of said patterns so that it: a. has a spatial frequency content distinct from the portions of said workpiece outside said regions, and b. defines a full planar figure of rotation.