Charged particle beam exposure system and method of compensating for eddy current effect on charged particle beam

A charged particle beam exposure system for compensating for the eddy current effect caused by leakage flux of a magnetic lens and motion of a stage carrying a substrate on which a focused charged particle beam is irradiated while the stage is moving at a velocity, said system comprising:

• deflecting means for deflecting the charged particle beam on a pattern in accordance with pattern signals;
• detecting means for detecting the position and velocity of the stage in a real time fashion, and for generating position data and velocity data;
• memory means for storing proportional constants for the relationship between the deviation in the path of the charged particle beam caused by the eddy current and the velocity of the stage, the proportional constants being measured in advance for a plurality of positions on the stage;
• correction generating means for generating correction signals which are a negative product of the proportional constants and the velocity data;
• and
• feedback means for feeding back the correction signals to said deflecting means.

A charged particle beam exposure system for compensating for the eddy current effect caused by leakage flux of a magnetic lens and motion of a stage carrying a substrate on which a focused charged particle beam is irradiated while being deflected in first and second directions to form a pattern while the stage is moving, the pattern being divided into a plurality of fields, each of which is further divided into a plurality of subfields, said system comprising:

• a central control unit for providing a main deflecting signal;
• a stage for supporting a substrate to be exposed to the charged particle beam, said stage being movable in first and second directions;
• a main deflector, coupled to said central control unit, for receiving the main deflecting signal and for deflecting the charged particle beam to one of the subfields in accordance with the main deflecting signal;
• a pattern generator for generating a pair of pattern signals corresponding to part of the pattern on said subfield when the stage is not moving;
• a sub-deflector coupled to said pattern generator for deflecting the charged particle beam to a position in said subfield in accordance with the pair of pattern signals respectively, which control the deflection of the charged particle beam in the first and second directions;
• stage controller means for moving said stage in the first and second directions under the command of said central control unit;
• stage detector means for detecting the position and velocity of said stage in a real time fashion, and for generating position data describing the position of said stage, first and second distance data respectively corresponding the distance of movement of said stage in the first and second directions during a time period from the time when the charged particle beam is deflected by said main deflector to the present time, and first and second velocity data describing the velocity of said stage;
• and
• correction generator means for generating a correction signal for correcting for the effect of movement of said stage and compensating for the eddy current effect, said correction generator means comprising:
• a first adder for respectively adding the first and second distance data to the pair of pattern signals;
• register means for storing proportional constants A, B, C and D;
• a set of first multipliers, coupled to said register means and said stage detector means, for respectively multiplying the first velocity data by the proportional constants A and C;
• a set of second multipliers, coupled to said register means and said stage detector means, for respectively multiplying the second velocity data by the proportional constants B and D;
• a set of second adders, coupled to said sets of first and second multipliers, for respectively adding the output of each of said first multipliers to the output of a corresponding one of said second multipliers;
• and
• a set of third adders for respectively adding the outputs of said first adder to the outputs of said second adders.

A charged particle beam exposure system for irradiating a substrate carried by a moving stage, comprising:

• a magnetic lens for focusing the charged particle beam, said magnetic lens having a leakage flux which produces an eddy current effect;
• means for providing pattern signals;
• detecting means for detecting the position and velocity of the stage in a real time fashion, and for generating velocity data;
• memory means for storing predetermined constants relating to a deviation in the path of the charged particle being caused by the eddy current;
• correction generating means for generating a correction signal based on the predetermined constants and the velocity data, and for generating a deflection signal by adding the correction signal and the pattern signals;
• and
• deflecting means for deflecting the charged particle beam onto the substrate in accordance with the deflection signal.

A method for compensating for an eddy current effect in a charged particle beam exposure system for irradiating a substrate carried by a moving stage, comprising the steps of:

• (a) determining proportional constants for the relationship between a deviation in the path of the charged particle beam caused by the eddy current and the velocity of the moving stage, the deviation being substantially proportional to the velocity of the stage;
• (b) generating a correction signal which is a product of the velocity of the stage and the proportional constants;
• and
• (c) superposing the correction signal on pattern signals which identify the position on a pattern to which the charged particle beam is to be deflected, so as to correct the deviation in the path of the charged particle beam.