US4357540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor device array mask inspection method and apparatus
Assignee: International Business Machines Corp
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Filing: 1980-12-19
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Granted: 1982-11-02
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Expires: 2000-12-19
Abstract
Abstract This describes an automatic beam alignment and defect inspection system for masks. The system causes each field or sub-field to be individually aligned for inspection irrespective of the previous alignment of the mask or any other field or sub-field. This is accomplished by scanning a preselected portion of each field of sub-field, with a beam and adjusting the position of the deflection based on the reflected signal while scanning a pre-established portion of the selected field or sub-field. In this way a portion of each selected field or sub-field is used as an alignment mark and stepping errors avoided. Once alignment is achieved a beam spot, comparable to the size of the minimum defect to be detected is scanned over the selected field or sub-field with an overlapping scan to find defects such as mask material in improper places or points where the mask material is missing.
Inventors
- 👤 Charles E. Benjamin
- 👤 David J. Crawford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:51
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/68; G03F1/82; G03F1/84; G03F1/86; H; H01; H01J; H01J37/00; H01J37/30; H01J37/304
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
225 words
A method of inspecting a patterned mask comprising the steps of: placing a patterned mask to be inspected in an inspection apparatus, said mask being provided with a multiplicity of patterns on a surface thereon, directing a beam to scan a first selected region overlying a portion of a selected first pattern on said mask, measuring the information received from said first region, comparing the measured information against the information used to create said mask and using the compared information to align said mask to a first predetermined position, directing the beam to scan the entire selected pattern, measuring the information received from said entire first selected pattern, comparing said received information to the information used to create said mask to detect errors in said selected pattern, moving said mask to a different position, directing the beam to scan a second selected region overlying a portion of a selected second pattern on said mask, comparing the measured information against the information used to create said mask and using the compared information to align said mask to a second predetermined position, directing the beam to scan the entire second selected pattern, measuring the information received from said entire second selected pattern, and comparing said received information from said second pattern to the information used to create said mask to detect errors in said second selected pattern.
Claim 2
Independent Claim
225 words
A method of inspecting a patterned mask comprising the steps of: placing a patterned mask to be inspected in an inspection apparatus, said mask being provided with a multiplicity of patterns on a surface thereon, directing a beam to scan a first selected region overlying a portion of a selected first pattern on said mask, measuring the information received from said first region, comparing the measured information against the information used to create said mask and using the compared information to align said mask to a first predetermined position, directing the beam to scan the entire selected pattern, measuring the information received from said entire first selected pattern, comparing said received information to the information used to create said mask to detect errors in said selected pattern, moving said mask to a different position, directing the beam to scan a second selected region overlying a portion of a selected second pattern on said mask, comparing the measured information against the information used to create said mask and using the compared information to align said mask to a second predetermined position, directing the beam to scan the entire second selected pattern, measuring the information received from said entire second selected pattern, and comparing said received information from said second pattern to the information used to create said mask to detect errors in said second selected pattern.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said beam is an optical beam.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein said beam is a beam of X-rays.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein said beam is an electron beam.
Claim 6
Dependent Claim
35 words
The method of claim 1 wherein said mask is comprised of a substrate and said patterns are formed of films thereon and said beam is selected so that said substrate is transparent to said beam.
Claim 7
Dependent Claim
13 words
The method of claim 5 wherein said films are opaque to said beam.
Claim 8
Dependent Claim
55 words
The method of claim 4 wherein said mask comprises a substrate coated with a conductive layer on which film patterns are deposited, said layer, said substrate and said film patterns having different reflective characteristics when impinged upon by said beam, and said measured information is in the form of reflected electrons from said scanned region.
Claim 9
Dependent Claim
21 words
The method of claim 5 wherein said substrate is glass and said beam is an optical beam in the visible range.
Claim 10
Dependent Claim
18 words
The method of claim 5 wherein said substrate is silicon and said beam is in the infrared range.
Claim 11
Dependent Claim
50 words
The method of claim 4 wherein said mask comprises a conductive substate on which film patterns are deposited, said substrate and said film patterns emit different levels of secondary electrons when scanned by said beam, and said measured information is in the form of secondary electrons from said scanned region.
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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) | 1985-11-01 | 1986-05-03 | 1986-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-01 | 1990-05-03 | 1990-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-01 | 1994-05-03 | 1994-11-02 | $7700.00 | Window Closed / Lapsed |