Patent US3854071A successfully refreshed from Google Patents.
US3854071A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure regulated scanning illumination means for electron projection systems
Assignee: International Business Machines Corp
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Filing: 1972-12-14
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Granted: 1974-12-10
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Expires: 1992-12-14
Abstract
Abstract The present invention relates to circuit means for use in combination with an electron beam projection system of the type wherein an image is projected onto a wafer by means of a scanning electron beam. The circuit means is employed to provide a regulated scan rate. In the system either the secondary electron current from the wafer or the wafer current itself is used to drive a pre-amplifier, the output of which is sent to a pair of attenuator networks to provide scan control. The outputs of the attenuators are fed to a pair of integrating amplifiers, the outputs of which are used to drive a pair of deflection amplifiers after passing through a pair of scan limit detectors and flyback circuits. The outputs of the deflection amplifiers are used to drive the X and Y deflection coils located before the final condenser lens.
Inventors
- 👤 M Heritage
- 👤 G Wardly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:30
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/30; H01J37/304; H01J37/02; H01J37/04; H01J37/147; H01J37/1472; H01J37/1474; H01J37/1475
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
201 words
In an electron beam projection system of the type including at least an electron beam source, a pair of deflection coils, for deflecting said electron beam in a raster mode and a target wafer onto which said electron beam is projected and scanned, the combination comprising: means for providing a regulated scanning rate for said system so that the instantaneous scan velocity is proportional to the current falling on the target wafer, said means including: means for detecting electron current from said target wafer being scanned by said electron beam; first and second feedback circuits connected to said electron current detection means, each of said feedback circuits including an attenuator means to provide a scan control signal, a deflection amplifier means connected to separate ones of said pair of deflection coils to produce deflection currents in said deflection coils; an integrating amplifier means interconnected to said attenuator means for integrating the electron current from said target wafer; and a scan limit detector means connected to said deflection amplifier means in each of said feedback circuits to detect when a given desired amplitude is attained by said deflection coil to provide a retrace of said electron beam back to its initial point.
Claim 2
Dependent Claim
201 words
In an electron beam projection system of the type including at least an electron beam source, a pair of deflection coils, for deflecting said electron beam in a raster mode and a target wafer onto which said electron beam is projected and scanned, the combination comprising: means for providing a regulated scanning rate for said system so that the instantaneous scan velocity is proportional to the current falling on the target wafer, said means including: means for detecting electron current from said target wafer being scanned by said electron beam; first and second feedback circuits connected to said electron current detection means, each of said feedback circuits including an attenuator means to provide a scan control signal, a deflection amplifier means connected to separate ones of said pair of deflection coils to produce deflection currents in said deflection coils; an integrating amplifier means interconnected to said attenuator means for integrating the electron current from said target wafer; and a scan limit detector means connected to said deflection amplifier means in each of said feedback circuits to detect when a given desired amplitude is attained by said deflection coil to provide a retrace of said electron beam back to its initial point.
Claim 3
Dependent Claim
33 words
An electron beam projection system according to claim 1 wherein said means for detecting said electron current from said target wafer is a means for detecting the secondary electron current from said wafer.
Claim 4
Dependent Claim
34 words
An electron beam projection system according to claim 1 wherein said means for detecting said electron current from said target wafer is a means connected to said wafer for directly Detecting the wafer current.
Claim 5
Dependent Claim
68 words
An electron beam projection system according to claim 1 further including a separate scan limit detector connected to the output of said integrating amplifier means in each of said feedback circuits, and a separate deflection amplifier connected between said scan limit detectors and a separate one of said pairs of deflection coils, said scan limit detectors functioning to sense a desired maximum scan amplitude of said electron beam.
Claim 6
Dependent Claim
46 words
An electron beam projection system according to claim 4 further including a feedback connection between said scan limit detector and said attenuator circuit in each of said feedback circuits for providing a retrace signal when said desired maximum scan amplitude of said electron beam is attained.
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) | 1977-12-09 | 1978-06-10 | 1978-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-09 | 1982-06-10 | 1982-12-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-09 | 1986-06-10 | 1986-12-10 | $7700.00 | Window Closed / Lapsed |