Charged particle beam drawing apparatus and pattern forming method

A charged particle beam drawing apparatus for having a drawing pattern exposed to a drawing area on a specimen by irradiation with a charged particle beam, the apparatus comprising:

• a charged particle beam exposing unit which performs supplementary exposure by irradiating said drawing area on said specimen with said charged particle beam, and which performs main exposure by irradiating with said charged particle beam a region constituted by said drawing pattern inside said drawing area on said specimen;
• and
• a computing device connected to said charged particle beam exposing unit by means of a data line,
• wherein said computing device divides said drawing area into a plurality of smaller regions of an equal area each;
• calculates an area value of said drawing pattern in each smaller region;
• corrects the area value of each smaller region by use of a weighted sum of the area values calculated for proximate smaller regions surrounding the smaller region in question, thereby computing a dose of main exposure for use by said charged particle beam exposing unit with regard to each smaller region of said specimen;
• generates supplementary exposure geometries in regard to said divided smaller regions;
• and computes doses of supplementary exposure for the generated supplementary exposure geometries by referring to the corrected area values;
• and
• wherein said computing device sends the computed doses of supplementary exposure and of main exposure to said charged particle beam exposing unit.

A charged particle beam drawing apparatus for having a drawing pattern exposed to a drawing area on a specimen by irradiation with a charged particle beam, the apparatus comprising:

• a charged particle beam exposing unit which performs supplementary exposure by irradiating said drawing area on said specimen with said charged particle beam, and which performs main exposure by irradiating with said charged particle beam a region constituted by said drawing pattern inside said drawing area on said specimen;
• an area computing unit which divides said drawing area into a plurality of smaller regions of an equal area each, and which calculates an area value of said drawing pattern in each smaller region;
• an area correcting unit which corrects the calculated area value of each smaller region by sue of a weighted sum of the area values calculated for proximate smaller regions surrounding the smaller region in question;
• a memory which stores the corrected area values;
• a main exposure dose computing unit which computes a dose of exposure for each smaller region based on the area values corrected by said area correcting unit;
• a geometry generating unit which generates supplementary exposure geometries in regard to said divided smaller regions;
• a supplementary exposure dose computing unit which refers to the corrected area values stored in said memory in order to expose said drawing area by doses of supplementary exposure using said supplementary exposure geometries generated by said geometry generating unit;
• and
• a data line which connects said main exposure dose computing unit and said supplementary exposure dose computing unit to said charged particle beam exposing unit, thereby allowing transmission of the doses of exposure and of supplementary exposure regarding each smaller region from the computing units to the exposing unit.

A pattern forming method for having a drawing pattern exposed to a drawing area on a specimen by irradiation with a charged particle beam, the method comprising the steps of:

• dividing said drawing pattern subject to exposure into a plurality of smaller regions while calculating an area value of said drawing pattern in each smaller region;
• correcting the area value of each smaller region by use of a weighted sum of the area values calculated for proximate smaller regions surrounding the smaller region in question;
• computing a dose of exposure for each smaller region on the basis of the corrected area values;
• generating supplementary exposure geometries in regard to said divided smaller regions;
• based on the corrected area values, computing doses of supplementary exposure for the generated supplementary exposure geometries by irradiation with said charged particle beam;
• performing supplementary exposure by irradiating said drawing area with said charged particle beam on the basis of the computed doses of supplementary exposure;
• and
• performing main exposure by irradiating a region constituted by said drawing pattern with said charged particle beam on the basis of the computed dose of exposure for each small region.

A charged particle beam drawing apparatus for having a drawing pattern exposed to a drawing area on a specimen by irradiation with a charged particle beam, the apparatus comprising:

• a charged particle beam exposing unit which performs supplementary exposure by irradiating said drawing area on said specimen with said charged particle beam, and which performs main exposure by irradiating with said charged particle beam a region constituted by said drawing pattern inside said drawing area on said specimen;
• and
• an exposure dose computing unit which divides said drawing area into a plurality of smaller regions;
• which obtains an area ratio of a drawing pattern region to a non-drawing pattern region in each of the divided smaller regions;
• and which computes a dose of said supplementary exposure to be smaller and a dose of said main exposure to be larger for a divided smaller region where said area ratio is relatively low than for a divided smaller region where said area ratio is relatively high.