Radiant energy – Means to align or position an object relative to a source or...
Reexamination Certificate
1999-10-20
2003-05-06
Berman, Jack (Department: 2881)
Radiant energy
Means to align or position an object relative to a source or...
C250S310000, C250S311000, C250S492100
Reexamination Certificate
active
06559456
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exposure method and apparatus which draw a pattern on a substrate such as a wafer or glass plate using a charged particle beam such as an electron beam or an ion beam.
2. Description of the Related Art
Electron beam exposure apparatuses are roughly classified into apparatuses for scanning a point beam on a wafer to draw a pattern and apparatuses for shaping an electron beam into a desired shape using a mask and transferring the mask pattern on a wafer. In both apparatuses, to expose a pattern on the entire wafer surface, the stage on which the wafer is placed must be moved to move the wafer relative to the electron beam.
In such a conventional apparatus, however, as the stage moves, the position of the electron beam changes accordingly, and the pattern cannot be drawn or transferred to the desired position on the wafer. This is probably because the electromagnetic field near the electron beam varies during movement of the stage. Especially, when a magnetic material is used for the stage which moves, the position of the electron beam conspicuously changes during movement of the stage.
Particularly, since the position of the electron beam changes during movement of the stage, the imaging characteristics (e.g., the focus position or astigmatic amount) of the electron beam may vary, and the pattern cannot be drawn or transferred to the desired position on the wafer. This is probably because the electromagnetic field near the electron beam varies during movement of the stage. Especially, when a magnetic material is used for the stage which moves, the imaging characteristics (e.g., the focus position or astigmatic amount) of the electron beam conspicuously vary during movement of the stage.
SUMMARY OF THE INVENTION
It is the object of the first and second aspects of the present invention to, e.g., suppress degradation in drawing accuracy due to a change in position of a charged particle beam during movement of a stage.
According to the first aspect of the present invention, there is provided an exposure method of placing a substrate on a stage and drawing a pattern on the substrate using a charged particle beam, comprising the correction step of correcting a position where the charged particle beam is incident on the substrate in drawing, in accordance with a position of the stage.
In the exposure method according to the first aspect of the present invention, for example, the correction step preferably comprises controlling a deflector for deflecting the charged particle beam to correct the position where the charged particle beam is incident on the substrate in drawing.
In the exposure method according to the first aspect of the present invention, for example, the correction step preferably comprises controlling the position of the stage to correct the position where the charged particle beam is incident on the substrate in drawing.
In the exposure method according to the first aspect of the present invention, for example, the correction step preferably comprises correcting a shift of the position where the charged particle beam is incident on the substrate, the shift being generated in accordance with the position of the stage.
In the exposure method according to the first aspect of the present invention, for example, the correction step preferably comprises correcting a reference position of the charged particle beam on the substrate in accordance with the position of the stage to correct the position where the charged particle beam is incident on the substrate in drawing.
In the exposure method according to the first aspect of the present invention, for example, the reference position is preferably a position where the charged particle beam is incident on the substrate without being deflected by a deflector.
In the exposure method according to the first aspect of the present invention, preferably, for example, the method further comprises the drawing step of drawing the pattern in each of a plurality of shot regions on the substrate, and the correction step comprises continuously correcting the position where the charged particle beam is incident on the substrate, in accordance with the position of the stage while the pattern is being drawn in each shot region.
In the exposure method according to the first aspect of the present invention, preferably, for example, the method further comprises the drawing step of drawing the pattern in each of a plurality of shot regions on the substrate while moving the stage to switch the shot region where the pattern is to be drawn, and the correction step comprises correcting the position where the charged particle beam is incident on the substrate, in accordance with a position of the shot region where the pattern is to be drawn.
In the exposure method according to the first aspect of the present invention, preferably, for example, the method further comprises the check step of checking a relationship between the position of the stage and the position where the charged particle beam is incident on the substrate, and the correction step comprises correcting the position where the charged particle beam is incident on the substrate in drawing, on the basis of a check result in the check step.
In the exposure method according to the first aspect of the present invention, for example, the check step preferably comprises checking a shift of the position where the charged particle beam is incident on the substrate, the shift being generated in accordance with the position of the stage.
In the exposure method according to the first aspect of the present invention, for example, the check step preferably comprises the placing step of placing a calibration substrate on the stage, the drawing step of drawing a calibration pattern on the calibration substrate, the detection step of detecting a position of the calibration pattern drawn in the drawing step, and the calculation step of calculating the difference between the position of the calibration pattern detected in the detection step and a designed position of the calibration pattern.
In the exposure method according to the first aspect of the present invention, preferably, for example, the drawing step comprises drawing the pattern using, as a target position, a designed reference position of the charged particle beam on the substrate, and the calculation step comprises calculating the difference between an actual reference position as the position of the pattern detected in the detection step and the designed reference position.
In the exposure method according to the first aspect of the present invention, for example, the correction step preferably comprises correcting the position where the charged particle beam is incident on the substrate in drawing such that the actual reference position matches the designed reference position.
In the exposure method according to the first aspect of the present invention, preferably, for example, the calibration substrate placed on the stage in the placing step is coated with a resist, the method further comprises the development step of developing the calibration substrate after the drawing step, and the detection step comprises detecting a position of a pattern formed in the development step.
In the exposure method according to the first aspect of the present invention, for example, the stage contains a magnetic material.
In the exposure method according to the first aspect of the present invention, for example, the stage is supported by static pressure bearings and a preloading mechanism.
In the exposure method according to the first aspect of the present invention, for example, the preloading mechanism comprises a magnetic preloading mechanism, a vacuum preloading mechanism, or an electrostatic preloading mechanism.
In the exposure method according to the first aspect of the present invention, for example, the charged particle beam is an electron beam.
According to the second aspect of the present invention, there is provided an exposure apparatus for drawing a pattern
Berman Jack
Fernandez K
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