Mask, method for forming a pattern, and method for evaluating pattern line width

A patterning method for forming a pattern, the method comprising:

• forming a pattern to be determined the line width of which is to be determined;
• and
• forming a pair of surrounding patterns with a same aperture rate near the pattern to be determined after the formation of the pattern to be determined, the pattern to be determined being located between the pair of surrounding patterns;
• wherein the case of forming the surrounding patterns, a plurality of pairs of surrounding patterns are formed near the pattern to be determined after the formation of the pattern to be determined, each pair having a same aperture rate, the pattern to be determined having a plurality of areas with each having the same line width, each of the plurality of areas being located between each of the plurality of pairs of surrounding patterns;
• and
• wherein when the plurality of pairs of surrounding patterns are formed near the pattern to be determined after the formation of the pattern to be determined, the plurality of pairs of surrounding patterns are formed so that an aperture rate of one pair of surrounding patterns will differ from an aperture rate of another pair of surrounding patterns.

A line width evaluation method for evaluating the line width, the method comprising:

• forming a plurality of pairs of surrounding patterns each of which have a same aperture rate, each of the plurality of pairs of surrounding patterns having therebetween each of a plurality of areas of a pattern to be determined, the plurality of areas each having the same line width;
• determining line width of the pattern to be determined in each of the plurality of areas located between each of the plurality of pairs of surrounding patterns by using an electron microscope;
• and
• using the line width of one area of the plurality of areas as a standard, comparing the line width of another area of the plurality of areas with the line width of the one area of the plurality of areas, and finding an amount of a determination error in the line width of the another area of the plurality of areas caused by charge-up;
• and
• wherein the case of forming the plurality of pairs of surrounding patterns, the plurality of pairs of surrounding patterns are formed so that an aperture rate of one pair of surrounding patterns will differ from an aperture rate of another pair of surrounding patterns.