Method of alignment between mask and semiconductor wafer

Claim 1

A method of alignment between a mask and a semiconductor wafer comprising steps of setting said semiconductor wafer on a stage, said semiconductor wafer including a first reflecting grating including a plurality of concaves or convexs arranged in a first direction with a constant pitch and a second reflecting grating including a plurality of concaves or convexs arranged in said first direction with a constant pitch which is a different value from said pitch of said first reflecting grating, the center in a second direction perpendicular to said first direction in the wafer plane of said second reflecting grating being separated from the center in said second direction of said first reflecting grating by a first distance in said second direction; superimposing said mask above said semiconductor wafer with a predetermined gap, said mask providing first and second linear Fresnel zone late lenses each including opaque and transparent stripes extending in said first direction and alternately arranged in said second direction, and the center line extending in said first direction of said first linear Fresnel zone plate lens being separated from the center line extending in said first direction of said second linear Fresnel zone plate lens by a second distance in said second direction, said second distance being smaller or larger than said first distance by a minute value; irradiating a monochromatic radiation on said first and second linear Fresnel zone plate lenses and focusing said radiation to form first and second slit-shape images of said radiation on said first and second reflecting gratings, respectively; detecting a first reflected radiation from said first reflecting grating through said first linear Fresnel zone plate lens by a first detector; detecting a second reflected radiation from said second reflecting grating through said second linear Fresnel zone plate lens by a second detector; obtaining a difference value between the outputs of said first and second detectors; and displacing the relative position between said mask and said semiconductor wafer in said second direction in accordance with said difference value until said difference value becomes minimum in absolute.

Claim 2

A method of alignment between a mask and a semiconductor wafer comprising steps of setting said semiconductor wafer on a stage, said semiconductor wafer including a first reflecting grating including a plurality of concaves or convexs arranged in a first direction with a constant pitch and a second reflecting grating including a plurality of concaves or convexs arranged in said first direction with a constant pitch which is a different value from said pitch of said first reflecting grating, the center in a second direction perpendicular to said first direction in the wafer plane of said second reflecting grating being separated from the center in said second direction of said first reflecting grating by a first distance in said second direction; superimposing said mask above said semiconductor wafer with a predetermined gap, said mask providing first and second linear Fresnel zone late lenses each including opaque and transparent stripes extending in said first direction and alternately arranged in said second direction, and the center line extending in said first direction of said first linear Fresnel zone plate lens being separated from the center line extending in said first direction of said second linear Fresnel zone plate lens by a second distance in said second direction, said second distance being smaller or larger than said first distance by a minute value; irradiating a monochromatic radiation on said first and second linear Fresnel zone plate lenses and focusing said radiation to form first and second slit-shape images of said radiation on said first and second reflecting gratings, respectively; detecting a first reflected radiation from said first reflecting grating through said first linear Fresnel zone plate lens by a first detector; detecting a second reflected radiation from said second reflecting grating through said second linear Fresnel zone plate lens by a second detector; obtaining a difference value between the outputs of said first and second detectors; and displacing the relative position between said mask and said semiconductor wafer in said second direction in accordance with said difference value until said difference value becomes minimum in absolute.

Claim 7

A method of alignment between a mask and a semiconductor wafer comprising steps of setting said semiconductor wafer on a stage, said semiconductor wafer including a first reflecting grating including a plurality of concaves or convexs arranged in a first direction with a constant pitch and a second reflecting grating including a plurality of concaves or convexs arranged in said first direction with a constant pitch which is a different value from said pitch of said first reflecting grating; superimposing said mask above said semiconductor wafer with a predetermined gap, said mask providing a linear Fresnel zone plate lens including opaque and transparent stripes extending in said first direction and alternately arranged in a second direction; irradiating a laser beam on said linear Fresnel zone plate lens and focusing said laser beam to form a slit-like image of said laser beam on said first reflecting grating and/or on said second reflecting grating; detecting a first reflected radiation from said first reflecting grating through said linear Fresnel zone plate lens by a first detector; detecting a second reflected radiation from said second reflecting grating through said linear Fresnel zone plate lens by a second detector; obtaining a difference value between the outputs of said first and second detectors; and displacing the relative position between said mask and said semiconductor wafer in said second direction in accordance with said difference value until said difference value becomes minimum in absolute.

Claim 8

A method of alignment between a mask and a semiconductor wafer comprising steps of setting said semiconductor wafer on a stage, said semiconductor wafer including a first reflecting grating including a plurality of concaves or convexs arranged in a first direction with a constant pitch and a second reflecting grating including a plurality of concaves or convexs arranged in said first direction with a constant pitch which is a different value from said pitch of said first reflecting grating; superimposing said mask above said semiconductor wafer with a predetermined gap, said mask providing a linear Fresnel zone plate lens including opaque and transparent stripes extending in said first direction and alternately arranged in a second direction; irradiating a laser beam on said linear Fresnel zone plate lens and focusing said laser beam to form a slit-like image of said laser beam on said first reflecting grating and/or on said second reflecting grating; detecting a first reflected radiation from said first reflecting grating through said linear Fresnel zone plate lens by a first detector; detecting a second reflected radiation from said second reflecting grating through said linear Fresnel zone plate lens by a second detector; obtaining a difference value between the outputs of said first and second detectors; and displacing the relative position between said mask and said semiconductor wafer in said second direction in accordance with said difference value until said difference value becomes minimum in absolute.