Method and apparatus for correcting proximity effect of electron beam
AssigneeInstitute of Microelectronics, Chinese Academy of Sciences
InventorsJian Xu, Yayi Wei, Shang Yang
Life of this patent
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Abstract
A method and an apparatus for correcting a proximity effect of an electron beam. An initial dose of the electron beam is preset for each exposed square, and proximity effect energy representing an influence of exposing all exposed squares other than a current exposed square on the current exposed is calculated. A corrected dose of the electron beam for the current exposed square is then calculated, and the corrected dose for each exposed square in the electron beam exposure layout matrix is successively calculated. Then, the above calculation iterates for T times to obtain a final corrected dose of the electron beam for each exposed square.
Claims10
A method for correcting a proximity effect of an electron beam, comprising:
- establishing a point spread function for energy distribution in a photoresist that is exposed to a unit dose of the electron beam;
- dividing a designed pattern through a grid to establish a pattern matrix for electron-beam exposure, wherein the pattern matrix comprises squares having identical dimensions;
- determining, for each exposed square in the pattern matrix, an initial dose of the electron beam and an energy threshold;
- calculating, for each exposed square, proximity effect energy based on the point spread function and the initial dose, wherein the proximity effect energy represents an influence of exposing all exposed squares other than said exposed square on energy deposition at said exposed square;
- calculating, for each exposed square, a corrected dose of the electron beam based on the proximity effect energy, the energy threshold, and the point spread function;
- wherein after the proximity effect energy and the corrected dose are calculated for each exposed square, the method further comprises:
- updating the corrected of the electron beam for each exposed square through a plurality of iterations to obtain a final corrected dose of the electron beam for each exposed square, wherein each of the plurality of iteration comprises:
- updating, for each exposed square, the proximity effect energy based on the point spread function and the corrected dose that is last calculated;
- and
- updating, for each exposed square, the corrected dose of the electron beam based on the updated proximity effect energy, the energy threshold, and the point spread function.
An apparatus for correcting a proximity effect of an electron beam, comprising:
- a memory storing computer-readable instructions;
- and
- a processor, wherein the computer-readable instructions when executed by the processor configures the apparatus to perform;
- establishing a point spread function for energy distribution in a photoresist that is exposed to a unit dose of the electron beam;
- dividing a designed pattern through a grid to establish a pattern matrix for electron-beam exposure, wherein the pattern matrix comprises squares having identical dimensions;
- determining for each exposed square in the pattern matrix, an initial dose of the electron beam and an energy threshold;
- calculating, for each exposed square, proximity effect energy based on the point spread function and the initial dose, wherein the proximity effect energy represents an influence of exposing all exposed squares other than exposed square on energy deposition at said exposed square;
- calculating, for each exposed square, a corrected dose of the electron beam based on the proximity effect energy, the energy threshold, and the point spread function,
- wherein after the proximity effect energy and the corrected dose are calculated for each exposed square, the method further comprises:
- updating the corrected dose of the electron beam for each exposed square through a plurality of iterations to obtain a final corrected dose electron beam for each exposed square, wherein each of the plurality of iterations comprises:
- calculating, for each exposed square, proximity effect energy based on the point spread function and the corrected dose that is last calculated;
- and
- calculating, for each exposed square, a corrected dose of the electron beam based on the proximity effect energy, the energy threshold, and the point spread function.
Dependencies are inferred from the claim text.