EP0065115A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Alignment apparatus for X-ray or optical lithography
Assignee: International Business Machines Corp
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Filing: 1982-04-21
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Granted: —
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Expires: 2002-04-21
Abstract
Abstract Fine alignment of mask (12) and wafer (13), using Fresnel zone plates is achieved by focussing light on the wafer using a zone plate in the mask. Light diffracted from a zone plate on the wafer is received by a sensor (14). The received light is coded (analog or digital) to indicate alignment. For analog coding the wafer zone plate diffracts light to the sensor from an area of the wafer zone plate which is indicative of alignment. For digital coding the wafer plate is digitally encoded as a function of alignment to similarly code the diffracted light.
Inventors
- 👤 Warren David Grobman
- 👤 David Albert Nelson, Jr.
- 👤 John Michael Warlaumont
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 11:45
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7073; G03F9/7076; G02; G02B; G02B5/00; G02B5/18; G02B5/1876; G03F9/7049
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
96 words
An alignment system wherein a first element to be aligned carries a Fresnel zone plate for focusing incident light to a line image on a grating mark carried by a second element to be aligned therewith, the grating mark diffracting line image light to a light sensor, characterized in that when there is misalignment the grating mark diffracts to the light sensor light from only a portion of the length of the line image, the size of the length portion of a line image diffracted to the light sensor varying as a function of alignment position.
Claim 2
Dependent Claim
96 words
An alignment system wherein a first element to be aligned carries a Fresnel zone plate for focusing incident light to a line image on a grating mark carried by a second element to be aligned therewith, the grating mark diffracting line image light to a light sensor, characterized in that when there is misalignment the grating mark diffracts to the light sensor light from only a portion of the length of the line image, the size of the length portion of a line image diffracted to the light sensor varying as a function of alignment position.
Claim 3
Dependent Claim
42 words
The alignment system of Claim 1 wherein the size of the length portion of the line image diffracted to the light sensor varies between two discrete values as a function of alignment position, said variation representing a digital code indicating alignment position.
Claim 4
Dependent Claim
28 words
The alignment system of Claim 1 wherein the size of the length portion of the line image diffracted to the light sensor is a measure of alignment position.
Claim 5
Dependent Claim
56 words
The system of Claim 2 or 3 in which said first element carries a plurality of Fresnel zone plates, each with a common focal length f l and in which said plurality of Fresnel zone plates is arranged as a macro Fresnel zone plate with focal length f2 , where f 2 # f 1 .
Claim 6
Dependent Claim
14 words
5 . The system of Claim 4 wherein f 2 > f l .
Claim 7
Dependent Claim
18 words
The system of Claim 4 in which f 2 is on the order of a centimeter or more.
Claim 8
Dependent Claim
21 words
The system of Claim 3 in which said grating mark includes one or more discontinuities arranged to digitally encode misalignment information.
Claim 9
Dependent Claim
57 words
A wafer with an alignment mark thereon for use in an optical alignment system, said alignment mark comprising a pattern of edges in a surface of said wafer, said pattern of edges comprising a first plurality of substantially parallel edges and second and third pluralities of edges, said second and said third pluralities comprising substantially converging edges.
Claim 10
Dependent Claim
57 words
A wafer with an alignment mark thereon for use in an optical alignment system, said alignment mark comprising a pattern of edges in a surface of said wafer, said pattern of edges comprising a first plurality of substantially parallel edges and second and third pluralities of edges, said second and said third pluralities comprising substantially converging edges.
Claim 11
Dependent Claim
19 words
The wafer of Claim 8 in which said second and third plurality of edges lie along two converging lines.
Claim 12
Dependent Claim
41 words
The wafer of Claim 8 in which said second and third plurality of edges comprise forming a series of lines with adjacent edges of progressively varying slope with respect to a line normal to other of said edges of said wafer.
Claim 13
Dependent Claim
14 words
The wafer of Claim 10 wherein said slope varies directly of inversely with misalignment.
Claim 14
Dependent Claim
16 words
The wafer of claim 11 wherein said slope varies inversely with misalignment as a quadratic function.
References Cited (Backward Citations)
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