Patent Number: 
Section: claims

1. A charged particle beam writing apparatus comprising:an emission unit configured to emit a charged particle beam;a stage on which a substrate serving as a writing target is placed and which is movable;a plurality of tracking calculation units each configured to calculate a deflection amount of the charged particle beam, for following movement of the stage, while having a calculation time difference wherein there exists a mutual overlapping time period;a switching unit configured, for each small region of a plurality of small regions made by virtually dividing a surface of the substrate, to input an end signal indicating that emission of the charged particle beam to a small region concerned has been completed, and to switch, using the end signal as a trigger, from output of one of the plurality of tracking deflection amount calculation units to output of another of the plurality of tracking deflection amount calculation units; anda deflector configured, while the stage is moving, to deflect the charged particle beam to an n-th small region, based on a signal output from one of the plurality of tracking deflection amount calculation units before switching the plurality of tracking deflection amount calculation units, and to deflect the charged particle beam to an (n+1)th small region, based on a signal output from another of the plurality of tracking deflection amount calculation units after switching the plurality of tracking calculation units. 2. The apparatus according to claim 1, further comprising:a false signal output unit configured, for each small region, to output a false signal of the end signal before emission of the charged particle beam to a small region concerned is completed,wherein the plurality of tracking calculation units input the false signal, and, using the false signal as a trigger, alternately start the to calculate. 3. The apparatus according to claim 1, whereinthe plurality of tracking calculation units and the switching unit are connected by an optical cable. 4. The apparatus according to claim 1, whereinthe deflector is configured by a multistage deflector, being two stages of a main deflector and a sub deflector,wherein the main deflector deflects, for each small region, the charged particle beam to a reference position of a small region concerned while following movement of the stage, andthe sub deflector deflects the charged particle beam to each shot position in the small region concerned. 5. The apparatus according to claim 1, further comprising:a detection unit configured, for each small region, to detect completion of writing to a small region concerned when the writing of the small region concerned has been completed, and to output the end signal. 6. The apparatus according to claim 2, further comprising:a first relay unit configured to include the false signal output unit; anda second relay unit configured to include the switching unit,wherein the plurality of tracking calculation units are connected to the first relay unit through a first optical cable, andthe plurality of tracking calculation units are connected to the second relay unit through a second optical cable. 7. A charged particle beam writing method comprising:emitting a charged particle beam;calculating, by a plurality of tracking calculation units, deflection amounts of the charged particle beam, for following movement of a stage on which a substrate serving as a writing target is placed, while having a calculation time difference wherein there exists a mutual overlapping time period;inputting, for each small region of a plurality of small regions made by virtually dividing a surface of the substrate, an end signal indicating that the emitting of the charged particle beam to a small region concerned has been completed, and switching, using the end signal as a trigger, from output of one of the plurality of tracking calculation units to output of another of the plurality of tracking calculation units;deflecting, while the stage is moving, the charged particle beam to an n-th small region, based on a signal output from one of the plurality of tracking calculation units before switching the plurality of tracking calculation units; anddeflecting, while the stage is moving, the charged particle beam to an (n+1)th small region, based on a signal output from another of the plurality of tracking calculation units after switching the plurality of tracking calculation units. 8. The method according to claim 7, further comprising:outputting, for each small region, a false signal of the end signal before the emitting of the charged particle beam to a small region concerned is completed,wherein the deflection amounts of the charged particle beam is, using the false signal as a trigger, started to be alternately calculated by the plurality of tracking calculation units. 9. The method according to claim 7, whereinthe charged particle beam is deflected, for each small region, to a reference position of a small region concerned while following movement of the stage, based on a signal output from one of the plurality of tracking calculation units. 10. The method according to claim 7, further comprising:detecting, for each small region, when writing to a small region concerned has been completed, a completion of the writing to the small region concerned, and outputting the end signal.