Exposure method and system for photolithography

A method of exposing a substrate for photolithography by the successive use of a first exposure apparatus having a first projection optical system and a second exposure apparatus having a second projection optical system, comprising the steps of:

• (a) comparing a first distortion characteristic within the projection range from the center of the field of view of said first projection optical system to a predetermined image height position and a second distortion characteristic within the projection range from the center of the field of view of said second projection optical system to said predetermined image height position during each relative magnification change of said first and second projection optical systems;
• (b) changing the projection magnification of at least one of said first and second projection optical systems so that said first and second distortion characteristics are most coincident with each other;
• and
• (c) disposing said substrate substantially at the same position relative to the centers of the fields of view of said first and second projection optical systems and exposing said substrate by said first and second exposure apparatuses in succession.

A method of superposition-exposing a substrate for photolithography by the successive use of a first exposure apparatus having a first projection optical system and a second exposure apparatus having a second projection optical system, comprising the steps of:

• (a) comparing a two-dimensional first distortion of the projected image by said first projection optical system and a two-dimensional second distortion of the projected image by said second projection optical system formed on partial areas on said substrate which are superposition-exposed;
• (b) determining the amount of relative shift in two-dimensional directions of the projected images by said first and second projection optical systems for minimizing a superposition error caused by the difference between said first distortion and said second distortion;
• and
• (c) exposing said substrate by said first and second exposure apparatuses in succession in a positional relation in which said projected images are shifted by said amount of shift from a design position.

An exposure system for photolithography comprising:

• a first exposure apparatus having a first projection optical system and means for supporting a substrate for photolithography so that the exposure center of said substrate is substantially coincident with the center of the projection field of view of said first projection optical system;
• a second exposure apparatus having a second projection optical system and means for supporting said substrate so that the same exposure center of said substrate is substantially coincident with the center of the projection field of view of said second projection optical system;
• and
• means for comparing a first distortion characteristic within the projection range from the center of the projection field of view of said first projection optical system to a predetermined image height position and a second distortion characteristic within the projection range from the center of the projection field of view of said second projection optical system to said predetermined image height position, and varying the projection magnification of at least one of said first and second projection optical systems so that said first and second distortion characteristics are most coincident with each other.

A method of superposition-exposing a substrate for photolithography by the successive use of a first exposure apparatus having a first projection optical system and a second exposure apparatus having a second projection optical system, comprising the steps of:

• (a) comparing a two-dimensional first distortion characteristic of said first projection optical system and a two-dimensional second distortion characteristic of said second projection optical system;
• (b) determining the amount of relative shift in two-dimensional directions of projection images formed on a partial area on said substrate by said first and second projection optical systems for minimizing a superposition error caused by the difference between said first distortion characteristic and said second distortion characteristic;
• (c) changing the projection magnification of at least one of said first and second projection optical systems so that said first and second distortion characteristics are most coincident with each other within said partial area;
• and
• (d) exposing said substrate by said first and second exposure apparatuses in succession in a positional relation in which said projected images are shifted by said amount of shift from a design position.

An exposure system for photolithography comprising:

• a first exposure apparatus includiog a first projection optical system having a two-dimensional first distortion and means for supporting a substrate for photolithography so that a partial area of said substrate is exposed to a projected image by said first projection optical system;
• a second exposure apparatus including a second projection optical system having a two-dimensional second distortion and means for supporting said substrate for photolithography so that said partial area of said substrate is exposed to a projected image by said second projection optical system;
• and
• means for comparing said first distortion and said second distortion and causing relative shift in two-dimensional directions of the projected images by said first and second projection optical systems so that a superposition error caused by the difference between said first distortion and said second distortion is minimized.

An exposure system for photolithography comprising:

• a first exposure apparatus including a first projection optical system having a two-dimensional first distortion characteristic and means for supporting a substrate for photolithography so that a partial area of said substrate is exposed to a projected image by said first projection optical system;
• a second exposure apparatus including a second projection optical system having a two-dimensional second distortion characteristic and means for supporting said substrate for photolithography so that said partial area of said substrate is exposed to a projected image by said second projection optical system;
• and
• means for comparing said first distortion characteristic within said partial area and said second distortion characteristic within said partial area, and varying the projection magnification of at least one of said first and second projection optical systems so that said first and second distortion characteristics are most coincident with each other.