Charged particle beam writing apparatus, and buffer memory data storage method

A charged particle beam writing apparatus comprising:

• a buffer memory configured to include a memory region capable of contemporarily storing writing data for a plurality of data processing regions obtained by virtually dividing a writing region to be written, wherein writing data including a plurality of data files is temporarily stored for each of the plurality of data processing regions;
• a dividing unit configured to divide the memory region of the buffer memory into a first region whose region size is large and a second region whose region size is small;
• a region specifying unit configured to specify the memory region of the buffer memory such that a data file whose file size is large has priority to be stored in the first region and a data file whose file size is small is stored at least in the second region, with respect to the plurality of data files for the each of the plurality of data processing regions included in the writing data;
• a data processing unit configured to read the plurality of data files corresponding to the each of the plurality of data processing regions from the buffer memory, and to perform data processing using the plurality of data files having been read;
• and
• a writing unit configured to write a pattern on a target object with charged particle beams, in accordance with content of the data processing, for the each of the plurality of data processing regions.