US4406546A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photoelectric detecting device
Assignee: Canon Inc
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Filing: 1980-07-31
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Granted: 1983-09-27
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Expires: 2000-07-31
Abstract
Abstract A photoelectric detecting device reads the alignment mark of a mask and the alignment mark of a wafer with high accuracy. In this device, a photoelectric detecting system for detecting the light reflected from the mask and a photoelectric detecting system for detecting the light reflected from the wafer are provided separately from each other to read the two marks with high accuracy. To distinguish between the light reflected from the mask and the light reflected from the wafer, a λ/4 plate is positioned between the mask and the wafer. The device also uses a polarized light beam to illuminate the mask and wafer.
Inventors
- 👤 Akiyoshi Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:30
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G03F9/7065
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
224 words
A photoelectric detecting apparatus for reading a pattern on a first sheet-like object and a pattern on a second sheet-like object, comprising: a light source projecting a polarized light beam therefrom; a scanning optical system for scanning the light beam on said first sheet-like object; an imaging system for forming the image of said first sheet-like object on said second sheet-like object with the scanning light beam; means disposed between said first sheet-like object and said second sheet-like object for varying the polarized condition of the scanning beam; first photoelectric means for receiving and detecting the reflected light from one of said sheet-like objects; second photoelectric means for receiving and detecting the reflected light from the other of said sheet-like objects; a polarization beam splitter disposed between said light source and first sheet-like object for directing said scanning light to said first sheet-like object and for directing the light reflected from said second sheet-like object to said first photoelectric means; a beam splitter disposed between said light source and said first sheet-like object for directing said scanning light to said first sheet-like object and for directing the light reflected therefrom to said second photoelectric means; and polarization means disposed between said first sheet-like object and said second photoelectric means, for directing only the light from the first sheet-like object to said second photoelectric means.
Claim 2
Dependent Claim
224 words
A photoelectric detecting apparatus for reading a pattern on a first sheet-like object and a pattern on a second sheet-like object, comprising: a light source projecting a polarized light beam therefrom; a scanning optical system for scanning the light beam on said first sheet-like object; an imaging system for forming the image of said first sheet-like object on said second sheet-like object with the scanning light beam; means disposed between said first sheet-like object and said second sheet-like object for varying the polarized condition of the scanning beam; first photoelectric means for receiving and detecting the reflected light from one of said sheet-like objects; second photoelectric means for receiving and detecting the reflected light from the other of said sheet-like objects; a polarization beam splitter disposed between said light source and first sheet-like object for directing said scanning light to said first sheet-like object and for directing the light reflected from said second sheet-like object to said first photoelectric means; a beam splitter disposed between said light source and said first sheet-like object for directing said scanning light to said first sheet-like object and for directing the light reflected therefrom to said second photoelectric means; and polarization means disposed between said first sheet-like object and said second photoelectric means, for directing only the light from the first sheet-like object to said second photoelectric means.
Claim 3
Dependent Claim
22 words
A photoelectric detecting apparatus as claimed in claim 1 wherein said first photoelectric means detects the reflected light in the dark field.
Claim 4
Dependent Claim
22 words
A photoelectric detecting apparatus as claimed in claim 1 wherein said second photoelectric means detects the reflected light in the bright field.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-26 | 1987-03-28 | 1987-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-26 | 1991-03-28 | 1991-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-26 | 1995-03-28 | 1995-09-27 | $7700.00 | Window Closed / Lapsed |