Multi charged particle beam writing method and multi charged particle beam writing apparatus

Abstract

A multi charged particle beam writing method includes calculating first shot positions of multiple beams, each of which includes a distortion amount of an irradiating corresponding beam, in a case of irradiating each beam, based on control grid intervals, calculating first condition positions based on a pre-set condition, each of which is arranged in a corresponding first region surrounded by closest second shot positions of 2×2 in length and width of the first shot positions, calculating, for each of second regions respectively surrounded by closest second condition positions of the first condition positions, an area density of a figure pattern in overlapping with a second region concerned, calculating an irradiation amount or an irradiation time of each beam whose corresponding first shot position is in a corresponding second region, based on an area density, and writing a pattern by irradiating a beam of the calculated irradiation amount or time.

What is claimed is: 
     
       1. A multi charged particle beam writing method comprising:
 calculating first shot positions of multiple beams, each of the first shot positions including a distortion amount of an irradiating corresponding beam, in a case of irradiating each beam of multiple beams of a charged particle beam on a target object, based on control grid intervals having been set in length and width in advance; 
 calculating first condition positions based on a pre-set condition, each of the first condition positions being arranged in a corresponding first region of a plurality of first regions respectively surrounded by closest second shot positions of 2×2 in length and width of the first shot positions, using the first shot positions including the distortion amount of the corresponding beam; 
 calculating, for each of a plurality of second regions respectively surrounded by a plurality of closest second condition positions of the first condition positions, an area density of a figure pattern to be written in overlapping with a second region concerned in the plurality of second regions, by using the first condition positions; 
 calculating an irradiation amount or an irradiation time of each beam whose corresponding first shot position of the first shot positions is in a corresponding second region of the plurality of second regions, based on an area density of a second region concerned; and 
 writing a pattern on a target object by irradiating a beam of the irradiation amount or the irradiation time calculated. 
 
     
     
       2. The method according to  claim 1 ,
 wherein the plurality of second regions are connected without any space. 
 
     
     
       3. The method according to  claim 1 ,
 wherein the first condition position is an average position or a gravity center position of the closest second shot positions surrounding the corresponding first region of the plurality of first regions. 
 
     
     
       4. The method according to  claim 1  further comprising:
 measuring a height position distribution of a writing region of the target object; and 
 correcting a focal position of each beam, where the focal position changes by a height position in the height position distribution, wherein distortion of the each beam includes a distortion resulting from the correcting the focal position. 
 
     
     
       5. The method according to  claim 1 ,
 wherein each of the plurality of second regions is surrounded by closest second condition positions of 2×2 in length and width as the plurality of closest second condition positions, and in a case there is an additional condition position which is to be added based on a pre-set condition, the each of the plurality of second regions is surrounded by the closest second condition positions of 2×2 in length and width and the additional condition position. 
 
     
     
       6. A multi charged particle beam writing apparatus comprising:
 a stage configured to mount a target object thereon and to be movable; 
 an emission unit emitter configured to emit a charged particle beam; 
 an aperture member, in which a plurality of openings are formed, configured to form multiple beams by letting a region including a whole of the plurality of openings be irradiated with the charged particle beam and letting portions of the charged particle beam respectively pass through a corresponding opening of the plurality of openings; 
 a plurality of blankers configured to respectively perform blanking deflection of a corresponding beam in the multiple beams having passed through the plurality of openings of the aperture member; 
 a blanking aperture member configured to block each beam that has been deflected to be in an off state by the plurality of blankers; 
 a deflector configured to collectively deflect each beam having passed through the blanking aperture member to each irradiation position on the target object for the each beam having passed through the blanking aperture member; 
 a shot position calculation unit configured by a circuit or a computer, to calculate first shot positions of multiple beams, each of the first shot positions including a distortion amount of an irradiating corresponding beam, in a case of irradiating each beam of multiple beams of a charged particle beam on a target object, based on control grid intervals having been set in length and width in advance; 
 a condition position calculation unit configured by a circuit or the computer, to calculate first condition positions based on a pre-set condition, each of the first condition positions being arranged in a corresponding first region of a plurality of first regions respectively surrounded by closest second shot positions of 2×2 in length and width of the first shot positions, using the first shot positions including the distortion amount of the corresponding beam; 
 an area density calculation unit configured by a circuit or the computer, to calculate, for each of a plurality of second regions respectively surrounded by a plurality of closest second condition positions of the first condition positions, an area density of a figure pattern to be written in overlapping with a second region concerned in the plurality of second regions, by using the first condition positions; 
 an irradiation time calculation unit configured by a circuit or the computer, to calculate an irradiation time of each beam whose corresponding first shot position is in a corresponding second region of the plurality of second regions, based on an area density of a second region concerned; and 
 a deflection control unit configured by a circuit or the computer, to perform blanking deflection control of the plurality of blankers so that each beam of the irradiation time calculated irradiates the target object. 
 
     
     
       7. The apparatus according to  claim 6 ,
 wherein the plurality of second regions are connected without any space. 
 
     
     
       8. The apparatus according to  claim 6 ,
 wherein the first condition position is an average position or a gravity center position of the closest second shot positions surrounding a first region of the plurality of first regions. 
 
     
     
       9. The apparatus according to  claim 6  further comprising:
 a sensor configured to measure a height position distribution of a writing region of the target object; and 
 an electrostatic lens configured to correct a focal position of each beam, where the focal position changes by a height position in the height position distribution, 
 wherein distortion of the each beam includes a distortion resulting from correcting the focal position. 
 
     
     
       10. The apparatus according to  claim 6 ,
 wherein each of the plurality of second regions is surrounded by closest second condition positions of 2×2 in length and width as the plurality of closest second condition positions, and in a case there is an additional condition position which is to be added based on a pre-set condition, the each of the plurality of second regions is surrounded by the closest second condition positions of 2×2 in length and width and the additional condition position. 
 
     
     
       11. The method according to claim 1,
 wherein when calculating said area density of the figure pattern for the each of the plurality of second regions, said area density is calculated using a plurality of second regions surrounding the second region concerned.    
     
     
       12. The method according to claim 11,
 wherein area densities in the second region concerned and the plurality of second regions surrounding the second region concerned are respectively calculated by weighting, for the each of the plurality of second regions, and   said area density used for calculating the irradiation amount or the irradiation time, becomes a statistical value of area densities weighted in the second region concerned and the plurality of second regions surrounding the second region concerned.    
     
     
       13. The method according to claim 12,
 wherein a weighting value for the second region concerned is different from weighting values for the plurality of second regions surrounding the second region concerned.    
     
     
       14. The method according to claim 12,
 wherein one of a sum and an average of area densities weighted in the second region concerned and the plurality of second regions surrounding the second region concerned is used as the statistical value.    
     
     
       15. The method according to claim 1,
 wherein the irradiation amount or the irradiation time is corrected by using a dose correction parameter.    
     
     
       16. The apparatus according to claim 6,
 wherein the area density calculation unit calculates said area density using a plurality of second regions surrounding the second region concerned for each of a plurality of second regions.    
     
     
       17. The apparatus according to claim 16,
 wherein the area density calculation unit calculates by weighting, area densities in the second region concerned and the plurality of second regions surrounding the second region concerned respectively, and   the area density calculation unit calculates a statistical value of area densities weighted in the second region concerned and the plurality of second regions surrounding the second region concerned, as said area density used for calculating the irradiation amount or   the irradiation time.    
     
     
       18. The apparatus according to claim 6 further comprising:
 a sensor configured to measure a height position distribution of a writing region of the target object; and   a lens configured to correct a focal position of each beam, where the focal position changes by a height position in the height position distribution,   wherein distortion of the each beam includes a distortion resulting from correcting the focal position.