Patent Number: 
Section: claims

1. An exposure apparatus which draws a pattern on a substrate with a plurality of charged-particle beams, comprising: a charged-particle beam generation source which generates a plurality of charged-particle beams grouped into a plurality of groups each formed from at least one charged-particle beam;  a magnetic lens array which is constituted by arraying a plurality of magnetic lenses corresponding to the plurality of groups between said charged-particle beam generation source and a substrate stage which supports the substrate, the plurality of magnetic lenses being excited by a common excitation unit;  a plurality of electron-optic elements which are arranged in correspondence with the plurality of groups and individually correct electron-optic characteristics of the plurality of magnetic lenses; and  a control system which controls the common excitation unit to adjust the electron-optic characteristics of the plurality of magnetic lenses at once, and individually controls said plurality of electron-optic elements to individually correct the electron-optic characteristics of the plurality of magnetic lenses, thereby optimizing an image formed on the substrate with the plurality of charged-particle beams grouped into the plurality of groups. 2. The apparatus according to  claim 1 , wherein said control system controls the common excitation unit so as to minimize a maximum value of differences between the electron-optic characteristics of the plurality of magnetic lenses and a target characteristic. claim 1 3. The apparatus according to  claim 1 , wherein said control system controls the common excitation unit and said plurality of electron-optic elements so as to make a focal position of each of the plurality of magnetic lenses coincide with a target position. claim 1 4. The apparatus according to  claim 1 , wherein each group is formed from a plural charged-particle beams. claim 1 5. The apparatus according to  claim 4 , wherein said control system controls the common excitation unit and said plurality of electron-optic elements every group so as to correct at least one of magnification and rotation of images each of which is formed on the substrate with the plural charged-particle beams of one group. claim 4 6. The apparatus according to  claim 5 , wherein claim 5 each electron-optic element has a plurality of deflectors which deflect a plurality of charged-particle beams passing through said electron-optic element, and  said control system individually controls the plurality of deflectors arranged for said electron-optic element, thereby correcting at least one of magnification and rotation of the image formed on the substrate. 7. The apparatus according to  claim 5 , wherein claim 5 each electron-optic element has a plurality of incident position changing elements which change incident positions of a plurality of charged-particle beams passing through said electron-optic element on corresponding magnetic lenses, and  said control system individually controls the plurality of incident position changing elements arranged for said electron-optic element, thereby correcting at least one of magnification and rotation of the image formed on the substrate. 8. A method of controlling an exposure apparatus which draws a pattern on a substrate with a plurality of charged-particle beams, wherein the exposure apparatus includes  a charged-particle beam generation source which generates a plurality of charged-particle beams grouped into a plurality of groups each formed from at least one charged-particle beam,  a magnetic lens array which is constituted by arraying a plurality of magnetic lenses corresponding to the plurality of groups between the charged-particle beam generation source and a substrate stage which supports the substrate, the plurality of magnetic lenses being excited by a common excitation unit, and  a plurality of electron-optic elements which are arranged in correspondence with the plurality of groups and individually correct electron-optic characteristics of the plurality of magnetic lenses,  the control method comprises  the first step of adjusting the electron-optic characteristics of the plurality of magnetic lenses at once by controlling the common excitation unit, and  the second step of individually correcting the electron-optic characteristics of the plurality of magnetic lenses by individually controlling the plurality of electron-optic elements, and  an image formed on the substrate with the plurality of charged-particle beams grouped into the plurality of groups is optimized by the first and second steps. 9. A manufacturing method of manufacturing a device through a lithography step, wherein the lithography step includes the step of drawing a pattern on a substrate using the exposure apparatus defined in  claim 1 .  claim 1 10. A manufacturing method of manufacturing a device through a lithography step, wherein the lithography step includes the step of drawing a pattern on a substrate using an exposure apparatus controlled by the control method defined in  claim 8 . claim 8