US5444257A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron-beam exposure system for reduced distortion of electron beam spot
Assignee: Fujitsu VLSI Ltd
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Filing: 1994-10-06
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Granted: 1995-08-22
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Expires: 2014-10-06
Abstract
Abstract An electron-beam exposure system includes an astigmatic compensation circuit that increases a voltage applied across a pair of electrodes forming an electrostatic sub-deflector and simultaneously decreases a voltage applied across another pair of electrodes forming the same electrostatic sub-deflector with a same magnitude as in the case of increasing the voltage, wherein the magnitude of the voltage change is changed in response to the deflection of the electron-beam caused by a main deflector.
Inventors
- 👤 Takamasa Satoh
- 👤 Hiroshi Yasuda
- 👤 Akio Yamada
- 👤 Junichi Kai
- 👤 Yoshihisa Oae
- 👤 Keiji Yamada
- 👤 Toru Oshima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:28
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/153; H01J2237/00; H01J2237/15; H01J2237/1504; H01J2237/153; H01J2237/1532; H01J2237/30; H01J2237/317; H01J2237/3175
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
285 words
An electron-beam exposure system for exposing a pattern on an object, comprising: a stage for holding the object to be exposed; an electron-beam source for producing an electron-beam, said electron-beam source emitting said electron-beam toward said object held on said stage along an optical axis; an electron optical system for focusing said electron-beam upon said object with demagnification; and a deflection fixture for deflecting said electron-beam such that said electron-beam moves over said object; said deflection fixture comprising: a main deflector for deflecting said electron-beam in a main deflection region defined on said object; a first drive circuit supplied with main deflection data indicative of a position of said electron-beam on said main deflection region, for driving said main deflector; an electrostatic sub-deflector for deflecting said electron-beam in a sub-deflection region included in said main deflection region and having an area substantially smaller than an area of said main-deflection region; and a second drive circuit supplied with sub-deflection data indicative of a position of said electron-beam in said sub-deflection region for driving said sub-deflector; said second drive circuit including an astigmatic compensation circuit supplied with astigmatic compensation data determined by said main deflection data, said compensation circuit shifting the level of a first voltage signal applied across a first pair of mutually opposing electrode plates forming said electrostatic deflector in an upward direction by a first correction voltage which is determined by said main deflection data, said astigmatic compensation circuit shifting simultaneously the level of a second voltage signal applied across a second pair of mutually opposing electrodes that also form said electrostatic deflector in a downward direction, by a second correction voltage having a magnitude identical with a magnitude of said first correction voltage.
Claim 2
Dependent Claim
285 words
An electron-beam exposure system for exposing a pattern on an object, comprising: a stage for holding the object to be exposed; an electron-beam source for producing an electron-beam, said electron-beam source emitting said electron-beam toward said object held on said stage along an optical axis; an electron optical system for focusing said electron-beam upon said object with demagnification; and a deflection fixture for deflecting said electron-beam such that said electron-beam moves over said object; said deflection fixture comprising: a main deflector for deflecting said electron-beam in a main deflection region defined on said object; a first drive circuit supplied with main deflection data indicative of a position of said electron-beam on said main deflection region, for driving said main deflector; an electrostatic sub-deflector for deflecting said electron-beam in a sub-deflection region included in said main deflection region and having an area substantially smaller than an area of said main-deflection region; and a second drive circuit supplied with sub-deflection data indicative of a position of said electron-beam in said sub-deflection region for driving said sub-deflector; said second drive circuit including an astigmatic compensation circuit supplied with astigmatic compensation data determined by said main deflection data, said compensation circuit shifting the level of a first voltage signal applied across a first pair of mutually opposing electrode plates forming said electrostatic deflector in an upward direction by a first correction voltage which is determined by said main deflection data, said astigmatic compensation circuit shifting simultaneously the level of a second voltage signal applied across a second pair of mutually opposing electrodes that also form said electrostatic deflector in a downward direction, by a second correction voltage having a magnitude identical with a magnitude of said first correction voltage.
Claim 3
Dependent Claim
101 words
An electron-beam exposure system as claimed in claim 1, wherein said astigmatic compensation circuit comprises: a first conversion circuit supplied with said sub-deflection data for producing said first voltage signal in response thereto; a second conversion circuit supplied with said sub-deflection data for producing said second voltage signal in response thereto; a first gain control circuit supplied with said astigmatic compensation data for modifying a gain of said first conversion circuit to a first direction; and a second gain control circuit supplied with said astigmatic compensation data for modifying a gain of said second conversion circuit in a second, opposite direction.
Claim 4
Dependent Claim
48 words
An electron-beam exposure system as claimed in claim 2, wherein each of said first and second gain control circuits comprises an operational amplifier having a feedback path and a variable resistor circuit inserted to said feedback path for changing a resistance in response to said astigmatic compensation data.
Claim 5
Dependent Claim
206 words
An electron-beam exposure system as claimed in claim 1, wherein said astigmatic compensation circuit comprises a first conversion circuit supplied with said sub-deflection data for producing said first voltage signal in response thereto; a second conversion circuit supplied with said sub-deflection data for producing said second voltage signal in response thereto; a first gain control circuit supplied with said astigmatic compensation data for changing a gain of said first conversion circuit in a first direction; a second gain control circuit supplied with said astigmatic compensation data for changing a gain of said second conversion circuit in a second, opposite direction;a first polarity control circuit for controlling said first gain control circuit such that voltage signals having respective, mutually opposing polarities and applied across a pair of electrode plates forming a first electrode pair as said first voltage signal, are changed in a direction of a first polarity with the same magnitude; and a second polarity control circuit for controlling said second gain control circuit such that voltage signals having respective, mutually opposing polarities and applied across a pair of electrode plates forming a second, different electrode pair, as said second voltage signal, are changed in a direction of a second, opposite polarity with the same magnitude.
Claim 6
Dependent Claim
49 words
An electron-beam exposure system as claimed in claim 1, wherein said astigmatic compensation circuit comprises a digital processor for carrying out an astigmatic correction; a digital-to-analog converter for converting output data of said digital processor to an output analog signal; and an amplifier for amplifying said output analog signal.
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) | 1998-08-21 | 1999-02-20 | 1999-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-21 | 2003-02-20 | 2003-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-21 | 2007-02-20 | 2007-08-22 | $7700.00 | Window Closed / Lapsed |