Method of measuring the bent shape of a movable mirror of an exposure apparatus

An exposure method for an exposure apparatus, which comprises:

• a two-dimensionally movable stage;
• a mirror provided to said stage;
• position measurement means for radiating a light beam onto said mirror, and measuring a position of said stage using the light beam reflected by said mirror;
• an illumination optical system for illuminating a mask;
• and
• a projection optical system for forming an image of said mask on a substrate placed on said stage, said method comprising:
• the first step of stepping said stage along array coordinates on the basis of a measured value of said position measurement means;
• the second step of sequentially exposing first and second measurement marks on a plurality of shot areas on said substrate, so that an image of said first measurement mark and images of said second measurement mark are formed at respective positions on said substrate, said mask having the first and second measurement marks;
• the third step of measuring differences between the positions of the images of the first and second measurement marks;
• the fourth step of calculating a relative array of the plurality of shot areas on said substrate on the basis of the differences between the positions of the images of the first and second measurement marks measured in the third step;
• the fifth step of calculating a bent shape of said mirror on the basis of the relative array of the plurality of shot areas on said substrate calculated in the fourth step;
• the sixth step of correcting a measured value of said position measurement means on the basis of the bent shape of said mirror;
• and
• the seventh step of forming an image of a transfer pattern on said substrate by stepping said stage on the basis of the measured value of said position measurement means, which value is corrected in the sixth step, said mask having the transfer pattern.

A method of measuring a bent shape of a mirror of an exposure apparatus, which comprises:

• a stage for holding a substrate and being movable along orthogonal first and second directions;
• a first mirror provided to said stage and having a plane reflector extending in said second direction;
• a second mirror provided to said stage and having a plane reflector extending in said first direction;
• a device for radiating light beams onto said first and second mirrors, and measuring the positions of said stage with respect to said first and second directions using light beams reflected by each of said mirrors;
• and
• an illumination optical system for illuminating a mask on which first and second marks are provided at different positions with respect to said first direction so as to form images of said first and second marks on said substrate, said method comprising:
• the first step of stepping said stage along at least the first direction according to array coordinates on the basis of a measured value of said device and sequentially exposing said first and second marks such that said images of said first mark and said second mark are formed at respective positions on said substrate with respect to the first direction and the second direction;
• the second step of measuring differences between the positions of the images of the first and second marks;
• and
• the third step of calculating a bent shape of at least said second mirror on the basis of the differences between the positions of the images of said first and second marks.