Electron beam apparatus and method of generating an electron beam irradiation pattern
View Patent ↗High-contrast exposure is performed by use of a small dose of electron beams, a pattern is formed on a wafer with high accuracy, and high-precision inspection is performed. In pattern formation, proximity effect correction processing is performed. Moreover, exposure of electron beams is performed based on a result of filtering using an inverse characteristic of exposure characteristics of the electron beams. Furthermore, in pattern inspection, electron beams are irradiated based on a result of filtering for obtaining a peripheral region of an edge of the pattern formed.
1. An electron beam apparatus which draws a pattern by performing raster scan of finely focused electron beams on a sample, comprising:
means for retaining drawing pattern data including a plurality of graphics as a bit map formed of pixels;
means for calculating a drawing pattern density based on the bit map;
means for correcting the bit map according to the drawing pattern density by adding a large additive correction amount to a value of each of the pixels included in the bit map in a region where the drawing pattern density is low and by adding a small additive correction amount thereto in a region where the drawing pattern density is high; and
means for controlling a dose of electron beams according to the value of each pixel in the corrected bit map.
2. The electron beam apparatus according to claim 1 , further comprising:
means for subjecting the data in the corrected bit map to filtering for sharpening, within a range in which the value of each pixel in the corrected bit map does not take on a negative value.
3. The electron beam apparatus according to claim 2 , wherein, in the filtering for sharpening, blur of the finely focused electron beams is approximated by a Gaussian filter, and a high-pass filter having an inverse characteristic of the Gaussian filter is used.
4. The electron beam apparatus according to claim 1 , wherein a plurality of the finely focused electron beams are raster scanned at the same time.
5. An electron beam irradiation pattern generation method for drawing a pattern by raster scanning finely focused electron beams on a sample, comprising the steps of:
converting drawing pattern data including a plurality of graphics into a bit map formed of pixels;
calculating a drawing pattern density based on the bit map;
correcting the bit map according to the drawing pattern density by adding a large additive correction amount to a value of each of the pixels included in the bit map in a region where the drawing pattern density is low and by adding a small additive correction amount thereto in a region where the drawing pattern density is high; and
obtaining an electron beam dose by performing filtering for sharpening within a range in which the value of each pixel in the corrected bit map does not take on a negative value.
6. An electron beam apparatus having a function of drawing an arbitrary graphic pattern by irradiating finely focused electron beam onto a sample, and a function of detecting a sample signal emitted from the sample by irradiating the finely focused electron beams onto the sample and of observing a shape of a sample surface, comprising:
means for converting drawing pattern data including a plurality of graphics into a bit map formed of pixels;
means for calculating a drawing pattern density based on the bit map;
means for correcting the bit map according to the drawing pattern density by adding a large additive correction amount to a value of each of the pixels included in the bit map in a region where the drawing pattern density is low and by adding a small additive correction amount thereto in a region where the drawing pattern density is high;
means for controlling a dose of electron beams according to the value of each pixel in the corrected bit map;
means for selecting between irradiation of at least one electron beam and irradiation of a plurality of electron beams for the plurality of electron beams;
at least one detection means for detecting the sample signal; and
means for performing image processing for an image obtained by the detection means,
wherein the electron beams irradiated onto the sample are formed of a plurality of finely focused electron beams.