Method and apparatus for correcting image distortions
First Claim
1. In an electron beam recording apparatus having means for deflecting a charged particle beam in the X and Y direction therein, the method for improving the geometric fidelity of the reproduced image comprising the steps of:
- (a) positioning a charged particle sensitive medium in the path of a charged particle beam to retain a permanent image on said medium,(b) projecting the particle beam to form on said medium a test pattern having a predetermined configuration,(c) providing a reference alignment image,(d) dividing each of the Xin and Yin signals into a plurality of non-interactive parallel correction circuits with each arranged to produce a correction signal for a predetermined spatial deviation shown on said medium,(e) comparing the deviation of the test pattern image with the reference alignment image for each of said predetermined spatial deviations, by measuring the deviations for a particular deflection distortion at a plurality of predetermined corresponding locations on said images,(f) adjusting each of the Xin and Yin deflection signal functions in each of said circuits so that the correction signal from each circuit is that for which it was determined, and(g) combining the sum of the signals from each of said plurality of correction circuits and summing the same with the Xin and Yin signal to produce total correction signals (Xc,Yc) to the X and Y deflection means whereby the test pattern image aligns with said reference alignment image.
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Accused Products
Abstract
A method and apparatus are described for improving the geometric fidelity of images reproduced in a charged particle beam device. The beam is deflected across a sensitive medium to form a test image of predetermined configuration. The test image is compared with a reference image and geometric deviations measured, at a number of points, are used to calculate correction signals required to modify the beam deflection to offset the deviations. Circuit adjustments are then made to provide the calculated correction signals. The correction signal adjustments are accomplished in separate non-interactive circuits for each of a plurality of predetermined corrections which only require a one time adjustment.
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Citations
23 Claims
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1. In an electron beam recording apparatus having means for deflecting a charged particle beam in the X and Y direction therein, the method for improving the geometric fidelity of the reproduced image comprising the steps of:
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(a) positioning a charged particle sensitive medium in the path of a charged particle beam to retain a permanent image on said medium, (b) projecting the particle beam to form on said medium a test pattern having a predetermined configuration, (c) providing a reference alignment image, (d) dividing each of the Xin and Yin signals into a plurality of non-interactive parallel correction circuits with each arranged to produce a correction signal for a predetermined spatial deviation shown on said medium, (e) comparing the deviation of the test pattern image with the reference alignment image for each of said predetermined spatial deviations, by measuring the deviations for a particular deflection distortion at a plurality of predetermined corresponding locations on said images, (f) adjusting each of the Xin and Yin deflection signal functions in each of said circuits so that the correction signal from each circuit is that for which it was determined, and (g) combining the sum of the signals from each of said plurality of correction circuits and summing the same with the Xin and Yin signal to produce total correction signals (Xc,Yc) to the X and Y deflection means whereby the test pattern image aligns with said reference alignment image. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit arrangement for providing in a charged particle beam deflection apparatus having beam deflection means for deflecting a single charged particle beam upon the application of Xin and Yin deflection signals thereto comprising:
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(a) a source of Xin and Yin deflection signals, (b) circuit means coupling said Xin and Yin signals to said beam deflection means for causing deflection of said charged particle beam, (c) a correction cirucit means for deriving Cx and Cy correction signals from Xin and Yin input signals coupled thereto, said correction signals each having a plurality of individually generated correction signal components, each of said components corresponding to a predetermined deflection distortion function not limited to KXm Yn on a recorded image from said beam, (d) means for coupling said Xin and Yin deflection signals to said correction circuit means, (e) said correction circuit means including separate and single function generating multiplier circuits means for deriving second and higher order signal components from said input (Xin, Yin) signals and means for combining the derived multiplier signals to provide a plurality of correction signal components, (f) said correction signal components each further including a plurality of individual adjustable circuit members for varying the amplitudes of associated correction signal component, (g) said adjustable circuit members each coupled in the circuit at a location for varying the amplitude of said correction signal component after signal multiplication, and (h) means for combining said Cx and Cy correction signals respectively and said deflection signals. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. In an electron beam recording apparatus having means for deflecting a charged particle beam in one direction therein, the method for improving the geometric fidelity of the reproduced image comprising the steps of:
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(a) positioning a charged particle sensitive medium in the path of a charged particle beam to retain a permanent image on said medium, (b) projecting the particle beam to form on said medium a test pattern having a predetermined configuration, (c) providing a reference alignment image, (d) dividing the deflection signal into a plurality of non-interactive parallel correction circuits with each arranged to produce a correction signal for a predetermined spatial deviation shown on said medium, (e) comparing the deviation of the test pattern image with the reference alignment image for each of said predetermined spatial deviations, by measuring the deviations for a particular deflection distortion at a plurality of predetermined corresponding locations on said images, (f) adjusting the deflection signal functions in each of said circuits so that the correction signal from each circuit is that for which it was determined, and (g) combining the sum of the signals from each of said plurality of correction circuits and summing the same with the deflection signal to produce a total correction signal to the deflection means whereby the test pattern image aligns with said reference alignment image. - View Dependent Claims (17, 18)
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19. A circuit arrangement for providing in a charged particle beam deflecting apparatus having single beam deflection means for deflecting a charged particle beam upon the application of a deflection signal thereto comprising;
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(a) a source of the deflection signal, (b) circuit means coupling said deflection signal to said beam deflection means for causing deflection of said charged particle beam, (c) a correction circuit means for deriving a correction signal from the input signal coupled thereto, said correction signal each having a plurality of individually generated correction signal components, each of said components corresponding to a predetermined deflection distortion function not limited to KXm Yn on a recorder image from said beam, (d) means for coupling said deflection signal to said correction circuit means, (e) said correction circuit means including separate and single function generating multiplier circuits means for deriving second and higher order signal components from said input signal and means for combining the derived multiplier signals to provide a plurality of correction signal components, (f) said correction signal components each further including a plurality of individual adjustable circuit members for varying the amplitudes of associated correction signal component, (g) said adjustable circuit members each coupled in the circuit at a location for varying the amplitude of said correction signal component after signal multiplication, and, (h) means for combining said correction signals respectively and said deflection signal. - View Dependent Claims (20, 21, 22)
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23. In a correction circuit arrangement for providing in a charged particle beam deflection apparatus having a single source of deflection signals Xin and Yin and deflection means for deflecting a charged particle beam upon the application for these deflection signals with circuit means for coupling said Xin and Yin signals to said correction circuit and to said beam deflection means and an additional means for combining correction signals Cx and Cy respectively with Xin and Yin for a composite correction deflection signal the improvement comprising:
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(a) means for deriving Cx and Cy correction signals from Xin and Yin input signals coupled thereto, said correction signals each having a plurality of individually generated correction signal components, each of said components corresponding to a predetermined deflection distortion function not limited to KXm Yn on a recorded image from said beam, said means including; (b) a first multiplier circuit means; (c) means coupling said first and higher order components to each of said first separate and single function generating multiplier circuit means for providing a plurality of output correction signal components from each of said multipliers each component associated with a scanning distortion not limited to KXm Yn ; (d) means for combining said plurality of correction signal components to provide said composite correction signals Xc and Yc, (e) adjustable circuit means coupled between said multiplier circuit means and said signal combining means for adjusting the amplitude of said signal to the signal combining means; (f) a second multiplier circuit means; (g) means for coupling said first and higher order components and said output correction signals of said first multiplier means to each of said second separate and single function generating multiplier circuit means wherein said second multiplier circuit means multiplies single function terms together for providing higher order output correction signal components from each of said multipliers than is provided by said first multiplier circuit means; (h) circuit means for coupling an output signal from said second multiplier circuit means to said signal combining means; and (i) means coupled between said first multiplier circuit means and said signal combining means for applying correction signal components of fixed amplitude to said signal combining means.
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Specification