Patent US4503334A successfully refreshed from Google Patents.
US4503334A
Expired / Lapsed
US
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Method of using an electron beam
Assignee: US Philips Corp
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Filing: 1982-10-18
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Granted: 1985-03-05
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Expires: 2002-10-18
Abstract
Abstract When an electron beam is used to effect a process at two adjacent surface areas of a target, such as a semiconductor wafer coated with an electron sensitive resist, various alignment errors can occur including wafer distortion. The provision of a reference marker, for example a square-etched depression, at the surface of the target between the adjacent surface areas enables detection of any misalignment. Thus, after effecting the process at one of the areas, an electron beam having substantially the same size and shape as the reference marker is directed toward the predetermined position of the reference marker. Back-scattered electrons are then detected to give a signal representative of any deviation between the actual position and the predetermined position of the reference marker so that the electron beam can be correctly aligned before carrying out the process at the second of the two surface areas. For increased accuracy of alignment, an array of reference markers may be provided between the two adjacent areas.
Inventors
- 👤 Hewson N. G. King
- 👤 James P. Beasley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:10
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/30; H01J37/304; H01J37/3045
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
131 words
In a method of using an electron beam to sequentially carry out a process at least at two adjacent surface areas of a target having at least one reference marker provided between said two adjacent surface areas, said method comprising the steps of carrying out said process at one of said two adjacent surface areas, thereafter directing an electron beam having the same size and shape as said reference marker toward a predetermined position of said reference marker, detecting back-scattered electrons from the area of said reference marker by a detection device, said detection device providing signals representative of deviations between the actual position and said predetermined position of said reference marker, and compensating for any said deviations before carrying out said process at another of said two adjacent surface areas.
Claim 2
Dependent Claim
131 words
In a method of using an electron beam to sequentially carry out a process at least at two adjacent surface areas of a target having at least one reference marker provided between said two adjacent surface areas, said method comprising the steps of carrying out said process at one of said two adjacent surface areas, thereafter directing an electron beam having the same size and shape as said reference marker toward a predetermined position of said reference marker, detecting back-scattered electrons from the area of said reference marker by a detection device, said detection device providing signals representative of deviations between the actual position and said predetermined position of said reference marker, and compensating for any said deviations before carrying out said process at another of said two adjacent surface areas.
Claim 3
Dependent Claim
21 words
A method according to claim 1, wherein said reference marker is provided as a depression in a surface of said target.
Claim 4
Dependent Claim
12 words
A method according to claim 2, wherein said reference marker is square.
Claim 5
Dependent Claim
19 words
A method according to claim 3, wherein said depression is provided by chemically etching said surface of said target.
Claim 6
Dependent Claim
56 words
A method according to claim 1, wherein said detection device includes two pairs of detectors arranged so that at least one pair of detectors provides differential signals when said predetermined position deviates from said actual position, said differential signals representing an extent of deviation in a direction parallel to a line between said pair of detectors.
Claim 7
Dependent Claim
34 words
A method according to claim 1, wherein an array of similar reference markers is provided between said two adjacent surface areas, and wherein said electron beam is directed to each reference marker in turn.
Claim 8
Dependent Claim
26 words
A method according to claim 6, wherein said signals obtained from said array of reference marks are integrated to provide an average value for said deviations.
Claim 9
Dependent Claim
21 words
A method according to claim 6, wherein said reference marker is provided as a depression in a surface of said target.
Claim 10
Dependent Claim
12 words
A method according to claim 6, wherein said reference marker is square.
Claim 11
Dependent Claim
19 words
A method according to claim 6, wherein said depression is provided by chemically etching said surface of said target.
Claim 12
Dependent Claim
56 words
A method according to claim 6, wherein said detection device includes two pairs of detectors arranged so that at least one pair of detectors provides differential signals when said predetermined position deviates from said actual position, said differential signals representing an extent of deviation in a direction parallel to a line between said pair of detectors.
Claim 13
Dependent Claim
30 words
A method according to claim 6, wherein said array includes at least a single row of said reference markers or a plurality of rows and columns of said reference markers.
Claim 14
Dependent Claim
48 words
A method according to claim 1, wherein an array of similar reference markers is provided between said two adjacent surface areas, and wherein said electron beam is directed only toward said predetermined position of one reference marker upon directing said electron beam toward each reference marker in turn.
Claim 15
Dependent Claim
21 words
A method according to claim 13, wherein said reference marker is provided as a depression in a surface of said target.
Claim 16
Dependent Claim
12 words
A method according to claim 13, wherein said reference marker is square.
Claim 17
Dependent Claim
19 words
A method according to claim 13, wherein said depression is provided by chemically etching said surface of said target.
Claim 18
Dependent Claim
14 words
A method according to claim 13, wherein said detection device is a single detector.
Claim 19
Dependent Claim
30 words
A method according to claim 13, wherein said array includes at least a single row of said reference markers or a plurality of rows and columns of said reference markers.
Claim 20
Dependent Claim
12 words
A method according to claim 1, wherein said reference marker is square.
Claim 21
Dependent Claim
19 words
A method according to claim 1, wherein said depression is provided by chemically etching said surface of said target.
Claim 22
Dependent Claim
22 words
A method according to claim 1, wherein said reference marker is an island of silicon oxide or a metal such as tantalum.
References Cited (Backward Citations)
US4145597A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |