US3811779A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for aligning a mask with respect to a semiconductor substrate
Assignee: US Philips Corp
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Filing: 1971-12-30
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Granted: 1974-05-21
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Expires: 1991-12-30
Abstract
Abstract An apparatus for aligning a mask comprising a large number of equal elements with respect to a semiconductor substrate is described. It is stated that for this purpose two patterns are used which each comprise at least three grating-shaped configurations of which two are oriented at right angles to one another and are spaced from one another by a distance which is small compared with the distance by which they are spaced from a third configuration the groove direction of which is substantially parallel to the line joining it to the two firstmentioned configurations. It is explained that one pattern is rigidly secured to the substrate and the other pattern is rigidly secured to the mask, images of the two patterns being formed about at the location of a reference pattern which also comprises at least three gratingshaped configurations.
Inventors
- 👤 B Jacobs
- 👤 P Kramer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:38
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7049; H; H10; H10P; H10P95/00
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
158 words
Apparatus for aligning a mask with respect to a semiconductor substrate, comprising for each direction with respect to which alignment is desired: a first phase grating attached to said substrate with the grating lines perpendicular to the direction on said substrate with respect to which alignment is desired; a second grating attached to said mask with the grating lines perpendicular to the corresponding direction on said mask with respect to which alignment is desired; a third reference grating; first and second light intensity detectors; means for optically imaging said first and second gratings tHrough said reference grating to said first and second detectors respectively; and means for modulating said images, whereby the respectively detected light intensities are periodically varying with respective phase angles which are a measure of the respective position of said first and second gratings, the difference between said phase angles being a measure of the relative position of said mask with respect to said substrate.
Claim 2
Dependent Claim
158 words
Apparatus for aligning a mask with respect to a semiconductor substrate, comprising for each direction with respect to which alignment is desired: a first phase grating attached to said substrate with the grating lines perpendicular to the direction on said substrate with respect to which alignment is desired; a second grating attached to said mask with the grating lines perpendicular to the corresponding direction on said mask with respect to which alignment is desired; a third reference grating; first and second light intensity detectors; means for optically imaging said first and second gratings tHrough said reference grating to said first and second detectors respectively; and means for modulating said images, whereby the respectively detected light intensities are periodically varying with respective phase angles which are a measure of the respective position of said first and second gratings, the difference between said phase angles being a measure of the relative position of said mask with respect to said substrate.
Claim 3
Dependent Claim
25 words
The apparatus as claimed in claim 1 wherein said means for modulating said images comprises means for modulating said reference grating in the period direction.
Claim 4
Dependent Claim
94 words
The apparatus as claimed in claim 1 wherein said means for imaging and means for modulating comprises: a source of plane-polarized light directed toward said first and second gratings, to produce respective diffraction patterns each having subbeams of different orders of diffraction; a phase-anisotropic element positioned in the path of a subbeam of each pattern, to polarize said subbeam differently from a subbeam of another order of diffraction; a lens to combine said differently polarized sub-beams of said respective diffraction patterns at said third grating; and an electro-optical modulator to modulate said combined subbeams.
Claim 5
Dependent Claim
75 words
Apparatus for aligning a mask with respect to a semi-conductor substrate, comprising for each direction with respect to which alignment is desired, a first group of elements as recited in claim 1, and a second group of elements as recited in claim 1, wherein the periods of said first, second, and third gratings of said first group are slightly different from the respective periods of said first, second, and third gratings of said second group.
Claim 6
Dependent Claim
109 words
The apparatus as defined in claim 1 wherein alignment is desired in three directions, the three first gratings attached to said substrate to correspond with said three directions and the three second gratings attached to said mask to correspond with said three directions forming an identical pattern on said substrate and on said mask in which pattern two gratings are oriented perpendicular to each other and spaced from each other by a distance which is small compared with the distance by which they are spaced from the other grating, the period direction of said other grating being perpendicular to a line joining said other grating with said two gratings.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |