Patent US6063531A successfully refreshed from Google Patents.
US6063531A
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Focus monitor structure and method for lithography process
Assignee: Advanced Micro Devices Inc
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Filing: 1998-10-06
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Granted: 2000-05-16
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Expires: 2018-10-06
Abstract
Abstract A focus monitor structure is placed on a reticle or mask near the production device structures, such as integrated circuits, to monitor the focal conditions of the lithography process as well as other parameters, such as the critical dimension, and proximity effects. The focus monitor structure includes a series of densely packed parallel lines and an isolated line along with a line that is positioned orthogonally to the densely packed lines forming an "L" shaped structure. The focus monitor structure also includes a plurality of rectangular islands that create post structures when patterned in the resist layer. The lines of the focus monitor structure are approximately the critical dimension and the rectangular islands vary in width between ±10% of the critical dimension. By manually or automatically inspecting the focus monitor structure after it is patterned into a layer of resist, including measuring the width of the resist lines and the resist profile angle of the orthogonal line, information relating to the critical dimension as well as the focal conditions of the lithography process can be determined.
Inventors
- 👤 Bhanwar Singh
- 👤 Bharath Rangarajan
- 👤 Khoi Anh Phan
- 👤 Carmen L. Morales
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:36
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70605; G03F7/70616; G03F7/70625; G03F7/70641
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
125 words
A test structure for monitoring a lithographic process on a substrate, said test structure comprising: at least one monitor structure comprising: a plurality of substantially parallel lines, each of said substantially parallel lines having a first width and separated by a first distance, said plurality of substantially parallel lines having a first length; at least one additional line positioned substantially parallel to said plurality of substantially parallel lines, said at least one additional line having said first width and a second length, wherein said second length is greater than said first length; at least one angled line positioned at an angle relative to said plurality of substantially parallel lines and said at least one additional line; and a plurality of rectangular islands on said substrate.
Claim 2
Dependent Claim
125 words
A test structure for monitoring a lithographic process on a substrate, said test structure comprising: at least one monitor structure comprising: a plurality of substantially parallel lines, each of said substantially parallel lines having a first width and separated by a first distance, said plurality of substantially parallel lines having a first length; at least one additional line positioned substantially parallel to said plurality of substantially parallel lines, said at least one additional line having said first width and a second length, wherein said second length is greater than said first length; at least one angled line positioned at an angle relative to said plurality of substantially parallel lines and said at least one additional line; and a plurality of rectangular islands on said substrate.
Claim 3
Dependent Claim
118 words
The test structure of claim 1, wherein said at least one monitor structure further comprises a dark field, said dark field comprising: a second plurality of substantially parallel lines, each of said second plurality substantially parallel lines having said first width and separated by said first distance, said second plurality of substantially parallel lines having said first length; a second at least one additional line positioned substantially parallel to said second plurality of substantially parallel lines, said at least one additional line having said first width and said second length; and a second at least one angled line positioned at an angle relative to said second plurality of substantially parallel lines and said at least one additional line.
Claim 4
Dependent Claim
37 words
The test structure of claim 1, wherein said at least one angled line is at least one orthogonal line positioned approximately orthogonally relative to said plurality of substantially parallel lines and said at least one additional line.
Claim 5
Dependent Claim
27 words
The test structure of claim 3, wherein said at least one orthogonal line is orthogonally connected to an outside line of said plurality of substantially parallel lines.
Claim 6
Dependent Claim
31 words
The test structure of claim 3, wherein there are two orthogonal lines, each of said two orthogonal lines orthogonally connected to an outside line of said plurality of substantially parallel lines.
Claim 7
Dependent Claim
18 words
The test structure of claim 3, wherein said first width and said first distance are the critical dimension.
Claim 8
Dependent Claim
46 words
The test structure of claim 3, wherein there are three rectangular islands on said substrate, said rectangular islands having said first width, a second width, and a third width, said second width greater than said first width and said third width less than said first width.
Claim 9
Dependent Claim
27 words
The test structure of claim 7, wherein said second width and said third width differ from said first width by a desired percentage of said first width.
Claim 10
Dependent Claim
12 words
The test structure of claim 8, wherein said desired percentage is 10%.
Claim 11
Dependent Claim
26 words
The test structure of claim 3, wherein said substrate is a lithographic reticle and said test structure is positioned at the four corners of said reticle.
Claim 12
Dependent Claim
31 words
The test structure of claim 1, wherein said test structure comprises at least two of said monitor structures, said at least two monitor structures being at an angle to one another.
Claim 13
Independent Claim
123 words
A method of monitoring the focal condition of a lithographic process, said method comprising: lithographically transferring a test structure from a reticle to a resist layer on a substrate, said test structure comprising at least one monitor structure comprising densely packed lines, at least one isolated line, an angled line positioned at an angle relative to said densely packed lines and said at least one isolated line, and a plurality of rectangular islands; developing said resist layer to produce a three dimensional image of said monitor structure; imaging an end of the three dimensional image of said angled line in said resist layer; and measuring the angle of the resist profile at said end of said three dimensional image of said angled line.
Claim 14
Independent Claim
123 words
A method of monitoring the focal condition of a lithographic process, said method comprising: lithographically transferring a test structure from a reticle to a resist layer on a substrate, said test structure comprising at least one monitor structure comprising densely packed lines, at least one isolated line, an angled line positioned at an angle relative to said densely packed lines and said at least one isolated line, and a plurality of rectangular islands; developing said resist layer to produce a three dimensional image of said monitor structure; imaging an end of the three dimensional image of said angled line in said resist layer; and measuring the angle of the resist profile at said end of said three dimensional image of said angled line.
Claim 15
Dependent Claim
36 words
The method of claim 12, wherein said at least one angled line is at least one orthogonal line positioned approximately orthogonally relative to said plurality of substantially parallel lines and said at least one additional line.
Claim 16
Dependent Claim
30 words
The method of claim 12, wherein imaging an end of the three dimensional image of said angled line is performed at an angle relative to the surface of said substrate.
Claim 17
Dependent Claim
41 words
The method of claim 12, further comprising monitoring the critical dimension generated by said lithographic process by measuring the width of at least one of the three dimensional image of said densely packed lines and said at least one isolated line.
Claim 18
Dependent Claim
17 words
The method of claim 15, further comprising altering the focus and exposure used in subsequent lithographic transferences.
Claim 19
Dependent Claim
18 words
The method of claim 16, wherein said altering the focus and exposure is performed by a process controller.
Claim 20
Dependent Claim
30 words
The method of claim 16, further comprising reprocessing said substrate when at least one of said critical dimension and said angle of said resist profile is outside a desired specification.
Claim 21
Dependent Claim
30 words
The method of claim 12, wherein said test structure comprises at least two of said monitor structures, said at least two monitor structures being at an angle to one another.
Claim 22
Independent Claim
128 words
A method of monitoring the focal condition of a lithographic process, said method comprising: lithographically transferring a monitor structure from a reticle to a resist layer on a substrate, said monitor structure comprising a plurality of rectangular islands, each of said plurality of rectangular islands having dimensions of approximately the critical dimension; developing said resist layer to produce a three dimensional image of said monitor structure; imaging at least a part of the three dimensional image of said plurality of rectangular islands; and monitoring the presence of the three dimensional image of said plurality of rectangular islands, wherein the absence of some of said three dimensional image of said plurality of rectangular islands indicates that the lithographic device is focused above the optical center of the resist layer.
Claim 23
Independent Claim
128 words
A method of monitoring the focal condition of a lithographic process, said method comprising: lithographically transferring a monitor structure from a reticle to a resist layer on a substrate, said monitor structure comprising a plurality of rectangular islands, each of said plurality of rectangular islands having dimensions of approximately the critical dimension; developing said resist layer to produce a three dimensional image of said monitor structure; imaging at least a part of the three dimensional image of said plurality of rectangular islands; and monitoring the presence of the three dimensional image of said plurality of rectangular islands, wherein the absence of some of said three dimensional image of said plurality of rectangular islands indicates that the lithographic device is focused above the optical center of the resist layer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-05-16 | 2003-11-15 | 2004-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-05-16 | 2007-11-15 | 2008-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-05-16 | 2011-11-15 | 2012-05-16 | $7700.00 | Window Closed / Lapsed |