Aligning apparatus and method for mitigating instability caused by interference in alignment signal

Claim 3

A method according to claim 1, wherein said first observing operation is carried out in the absence of said second body thereby to create said first conditions.

Claim 4

A method according to claim 2, wherein said first and said second bodies are so constructed that when said alignment mark on said second body is aligned with said first zone, said second body does not extend to a region aligned with said second zone on said first body, thereby to create said second conditions.

Claim 5

A method according to claim 1, wherein said observing operations are carried out by a scanning light beam.

Claim 6

A method according to claim 1, wherein gating is performed, in response to said first signals, during the obtaining of said second signals.

Claim 7

A method according to claim 5, wherein said first and said second electrical signals comprise pulses, obtained in response to detection of said alignment marks, on said first and said second bodies during said first and said second observing operations and wherein time periods between pulses obtained during said first observing operation and between pulses obtained during said second observing operation are measured and utilized for bringing said bodies into the desired positional relationship.

Claim 8

A method according to claim 6, wherein said gating is performed during said second observing operation to permit the production of a pulse produced by reflection of light by said alignment mark on said second body and to eliminate pulses produced by reflection of light from said first alignment mark on said first body.

Claim 9

Apparatus for aligning a first body with a second said body, said first body being characterized in that light may be transmitted therethrough to the second body, said first body having a first and second alignment marks in respective first and second zones thereon, said second body having an alignment mark thereon; said apparatus comprising: observing means for observing the regions of said first and second zones on said first body; obtaining means for obtaining, in response to a first observing operation through said observing means carried out under first conditions in which there is substantially no influence from any light transmitted through said first body at said first and second zones, first electrical signals dependent upon the relative positions of said first and said second alignment marks on said first body; and for obtaining, in response to a second observing operation through said observing means carried out with said alignment mark on said second body aligned with said first zone and under second conditions in which there is substantially no influence from any light transmitted through said first body at said second zone, second electrical signals dependent upon the relative position of said second alignment mark on said first body and said alignment mark on said second body; and means for bringing said first and said second bodies into a desired positional relationship utilizing said first and said second electrical signals.

Claim 10

Apparatus for aligning a first body with a second said body, said first body being characterized in that light may be transmitted therethrough to the second body, said first body having a first and second alignment marks in respective first and second zones thereon, said second body having an alignment mark thereon; said apparatus comprising: observing means for observing the regions of said first and second zones on said first body; obtaining means for obtaining, in response to a first observing operation through said observing means carried out under first conditions in which there is substantially no influence from any light transmitted through said first body at said first and second zones, first electrical signals dependent upon the relative positions of said first and said second alignment marks on said first body; and for obtaining, in response to a second observing operation through said observing means carried out with said alignment mark on said second body aligned with said first zone and under second conditions in which there is substantially no influence from any light transmitted through said first body at said second zone, second electrical signals dependent upon the relative position of said second alignment mark on said first body and said alignment mark on said second body; and means for bringing said first and said second bodies into a desired positional relationship utilizing said first and said second electrical signals.

Claim 11

Apparatus according to claim 8, wherein said observing means comprises means for forming a light beam and means for causing said light beam to scan said first and second bodies.

Claim 12

Apparatus according to claim 8, wherein said obtaining means is operable to derive a gating signal from said first electrical signals and to obtain said second electrical signals with the aid of said gating signal.

Claim 13

Apparatus according to claim 10, wherein said obtaining means obtains said first and said second electrical signals as pulses obtained in response to detection of said alignment marks during said observing operations, wherein said apparatus further comprises means for measuring time periods between said pulses obtained during said first observing operation and between said pulses obtained during said second observing operation, and whether said means for bringing said first and said second bodies into a desired positional relationship utilizes said time periods.

Claim 14

Apparatus according to claim 11, wherein said obtaining means is operable to produce said gating signal during said second observing operation so as to permit the production of a pulse in response to detection of light reflected from said alignment mark on said second body while eliminating pulses produced in response to detection of light reflected from said first alignment mark on said first body.

Claim 15

Apparatus according to claim 8, wherein said observing means includes first and second objective lenses for observing said first and second zones of said body respectfully.