US5982044A
Expired / Lapsed
US
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Alignment pattern and algorithm for photolithographic alignment marks on semiconductor substrates
Assignee: Vanguard International Semiconductor Corp
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Filing: 1998-04-24
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Granted: 1999-11-09
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Expires: 2018-04-24
Abstract
Abstract Novel triangular alignment marks and a novel algorithm are used to provide improved global alignment of the substrate on a substrate stage in an align-and expose tool. The method provides an improved metrology for aligning to a recessed alignment mark in the substrate having a material layer, such as insulating, polysilicon, and conducting layers that are inadvertently made asymmetric by processing such as chemical/mechanically polishing. The method also employs an algorithm that detects the recessed edges of the triangle and mathematically generates three lines representing the edges of the triangle. The algorithm then generates a family of lines moving inward from the edges of the triangular alignment marks and parallel to the edges until the lines converge to a common point which determines the alignment center for the triangular alignment marks. The algorithm uses the coordinates of the alignment center to position the substrate in the exposure tool for a coarse alignment the photomask for exposing a photoresist layer on the substrate. This new alignment mark and new algorithm minimize misalignment due to asymmetric formation of a material layer over the alignment mark.
Inventors
- 👤 Hua-Tai Lin
- 👤 Gwo-Yuh Shiau
- 👤 Pin-Ting Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:11
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7092; G03F9/7073; G03F9/708; G03F9/7084; H; H10; H10W; H10W46/00; H10W46/101; H10W46/201; H10W46/301; H10W46/501; Y; Y10; Y10S; Y10S148/00; Y10S148/102
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
194 words
A method for making novel alignment marks on a substrate and an algorithm for aligning said substrate to a photomask in a photoresist exposure tool comprising the steps of: forming at least two said alignment marks triangular in shape recessed in said substrate near the perimeter; said substrate having a material layer that can have an asymmetric profile over said recessed alignment marks; forming a photoresist layer on said material layer; providing said algorithm encoded in permanent memory for said exposure tool that detects the edges of said recessed triangular alignment marks and mathematically defines three lines parallel to said edges of said triangular alignment mark; and further, said algorithm generates a family of lines moving inward from said edges of said triangular alignment marks and parallel to said edges until said lines converge to a common point which determines the alignment center for said triangular alignment marks; said algorithm then uses the coordinates of said alignment center to position said substrate in said exposure tool to said photomask for exposing said photoresist, wherein said alignment mark and said algorithm minimize misalignment due to asymmetric formation of said material layer over said alignment marks.
Claim 2
Independent Claim
194 words
A method for making novel alignment marks on a substrate and an algorithm for aligning said substrate to a photomask in a photoresist exposure tool comprising the steps of: forming at least two said alignment marks triangular in shape recessed in said substrate near the perimeter; said substrate having a material layer that can have an asymmetric profile over said recessed alignment marks; forming a photoresist layer on said material layer; providing said algorithm encoded in permanent memory for said exposure tool that detects the edges of said recessed triangular alignment marks and mathematically defines three lines parallel to said edges of said triangular alignment mark; and further, said algorithm generates a family of lines moving inward from said edges of said triangular alignment marks and parallel to said edges until said lines converge to a common point which determines the alignment center for said triangular alignment marks; said algorithm then uses the coordinates of said alignment center to position said substrate in said exposure tool to said photomask for exposing said photoresist, wherein said alignment mark and said algorithm minimize misalignment due to asymmetric formation of said material layer over said alignment marks.
Claim 3
Dependent Claim
17 words
The method of claim 1, wherein said alignment marks recessed in said substrate have equilateral triangular shapes.
Claim 4
Dependent Claim
13 words
The method of claim 1, wherein said material layer is a polysilicon layer.
Claim 5
Dependent Claim
13 words
The method of claim 1, wherein said material layer is a conducting layer.
Claim 6
Dependent Claim
13 words
The method of claim 1, wherein said material layer is an insulating layer.
Claim 7
Dependent Claim
26 words
The method of claim 1, wherein said material layer is a chemically/mechanically polished layer that can result in asymmetric polishing resulting in misalignment between masking levels.
Claim 8
Dependent Claim
21 words
The method of claim 1, wherein said material layer is composed of any material used in the fabrication of semiconductor devices.
Claim 9
Dependent Claim
30 words
The method of claim 1, wherein said algorithm that generates said family of lines that converge to said common point, wherein said common point is within a required alignment tolerance.
Claim 10
Dependent Claim
14 words
The method of claim 1, wherein said permanent memory is a magnetic storage device.
Claim 11
Dependent Claim
26 words
The method of claim 1, wherein said photomask is also used to expose and develop said photoresist layer to form photoresist patterns for making semiconductor devices.
Claim 12
Independent Claim
195 words
A method for making novel alignment marks on a substrate and an algorithm for aligning said substrate to a photomask in a photoresist exposure tool comprising the steps of: forming at least two said alignment marks having equilateral triangular shapes recessed in said substrate near the perimeter; said substrate having a material layer that can have an asymmetric profile over said recessed alignment marks; forming a photoresist layer on said material layer; providing said algorithm encoded in permanent memory for said exposure tool that detects the edges of said recessed triangular alignment marks and mathematically defines three lines parallel to said edges of said triangular alignment mark; and further, said algorithm generates a family of lines moving inward from said edges of said triangular alignment marks and parallel to said edges until said lines converge to a common point which determines the alignment center for said triangular alignment marks; said algorithm then uses the coordinates of said alignment center to position said substrate in said exposure tool to said photomask for exposing said photoresist, wherein said alignment mark and said algorithm minimize misalignment due to asymmetric formation of said material layer over said alignment marks.
Claim 13
Independent Claim
195 words
A method for making novel alignment marks on a substrate and an algorithm for aligning said substrate to a photomask in a photoresist exposure tool comprising the steps of: forming at least two said alignment marks having equilateral triangular shapes recessed in said substrate near the perimeter; said substrate having a material layer that can have an asymmetric profile over said recessed alignment marks; forming a photoresist layer on said material layer; providing said algorithm encoded in permanent memory for said exposure tool that detects the edges of said recessed triangular alignment marks and mathematically defines three lines parallel to said edges of said triangular alignment mark; and further, said algorithm generates a family of lines moving inward from said edges of said triangular alignment marks and parallel to said edges until said lines converge to a common point which determines the alignment center for said triangular alignment marks; said algorithm then uses the coordinates of said alignment center to position said substrate in said exposure tool to said photomask for exposing said photoresist, wherein said alignment mark and said algorithm minimize misalignment due to asymmetric formation of said material layer over said alignment marks.
Claim 14
Dependent Claim
13 words
The method of claim 11, wherein said material layer is a polysilicon layer.
Claim 15
Dependent Claim
13 words
The method of claim 11, wherein said material layer is a conducting layer.
Claim 16
Dependent Claim
13 words
The method of claim 11, wherein said material layer is an insulating layer.
Claim 17
Dependent Claim
26 words
The method of claim 11, wherein said material layer is a chemically/mechanically polished layer that can result in asymmetric polishing resulting in misalignment between masking levels.
Claim 18
Dependent Claim
21 words
The method of claim 11, wherein said material layer is composed of any material used in the fabrication of semiconductor devices.
Claim 19
Dependent Claim
30 words
The method of claim 11, wherein said algorithm that generates said family of lines that converge to said common point, wherein said common point is within a required alignment tolerance.
Claim 20
Dependent Claim
14 words
The method of claim 11, wherein said permanent memory is a magnetic storage device.
Claim 21
Dependent Claim
26 words
The method of claim 11, wherein said photomask is also used to expose and develop said photoresist layer to form photoresist patterns for making semiconductor devices.
Claim 22
Dependent Claim
190 words
Novel alignment marks on a substrate and an algorithm for aligning said substrate to a photomask in a photoresist exposure tool comprising the steps of: said substrate having at least two said alignment marks triangular in shape recessed in said substrate near the perimeter; a material layer that can have an asymmetric profile over said recessed alignment marks in said substrate; a photoresist layer formed on said material layer; said algorithm encoded in permanent memory for said exposure tool that detects the edges of said recessed triangular alignment marks and mathematically defines three lines parallel to said edges of said triangular alignment mark; and further, said algorithm generates a family of lines moving inward from said edges of said triangular alignment marks and parallel to said edges until said lines converge to a common point which determines the alignment center for said triangular alignment marks; said algorithm uses the coordinates of said alignment center to position said substrate in said exposure tool to said photomask for exposing said photoresist, wherein said alignment mark and said algorithm minimize misalignment due to asymmetric formation of said material layer over said alignment marks.
Claim 23
Dependent Claim
190 words
Novel alignment marks on a substrate and an algorithm for aligning said substrate to a photomask in a photoresist exposure tool comprising the steps of: said substrate having at least two said alignment marks triangular in shape recessed in said substrate near the perimeter; a material layer that can have an asymmetric profile over said recessed alignment marks in said substrate; a photoresist layer formed on said material layer; said algorithm encoded in permanent memory for said exposure tool that detects the edges of said recessed triangular alignment marks and mathematically defines three lines parallel to said edges of said triangular alignment mark; and further, said algorithm generates a family of lines moving inward from said edges of said triangular alignment marks and parallel to said edges until said lines converge to a common point which determines the alignment center for said triangular alignment marks; said algorithm uses the coordinates of said alignment center to position said substrate in said exposure tool to said photomask for exposing said photoresist, wherein said alignment mark and said algorithm minimize misalignment due to asymmetric formation of said material layer over said alignment marks.
Claim 24
Dependent Claim
14 words
The structure of claim 20, wherein said alignment marks are equilateral triangles in shape.
Claim 25
Dependent Claim
15 words
The structure of claim 20, wherein said algorithm is encoded on a magnetic storage device.
Claim 26
Dependent Claim
15 words
The structure of claim 20, wherein said algorithm is encoded in a read-only memory (ROM).
Claim 27
Dependent Claim
22 words
The structure of claim 20, wherein said algorithm is encoded in a non-volatile memory comprised of an electrically programmable read-only memory (EPROM).
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-11-08 | 2003-05-10 | 2003-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-08 | 2007-05-10 | 2007-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-08 | 2011-05-10 | 2011-11-09 | $7700.00 | Window Closed / Lapsed |