Method of computing defocus amount in lithography and lithographic process using the method

A method of computing a defocus amount in lithography, comprising the steps of:

• measuring line width and edge roughness of a resist pattern formed by lithography;
• calculating, based on the measured line width and the measured edge roughness, the amount of defocus of a pseudo-profile of the beam used in said lithography;
• preparing a plurality of said resist patterns by lithography while employing, for different resist patterns, different values of a particular lithographic factor as a parameter among the lithographic factors that contribute to the defocus of said pseudo-profile of the beam;
• conducting the measurement of the line width and the edge roughness for each of said resist patterns;
• calculating the amounts of defocus based on the line widths and edge roughnesses of the respective resist patterns as obtained with said different values of said particular lithographic factor;
• and
• calculating the dependency of said amount of defocus on said particular lithographic factor.

A lithographic process, comprising the steps of:

• measuring line width and edge roughness of a resist pattern formed by lithography;
• calculating, based on the measured line width and the measured edge roughness, the amount of defocus of a pseudo-profile of the beam used in said lithography;
• optimizing a lithographic factor that has caused the defocus of said pseudo-profile of the beam, based on said amount of defocus;
• subtracting, after the step of calculating said amount of defocus of said pseudo-profile of the beam, the defocus components attributable to all other lithographic factors than a particular lithographic factor from said amount of defocus of said pseudo-profile of the beam, thereby extracting the amount of defocus attributable to said particular lithographic factor;
• wherein the optimizing step optimizes said particular lithographic factor.

A lithographic process, comprising the steps of:

• measuring line width and edge roughness of a resist pattern formed by lithography;
• calculating, based on the measured line width and the measured edge roughness, the amount of defocus of a pseudo-profile of the beam used in said lithography;
• optimizing a lithographic factor that has caused the defocus of said pseudo-profile of the beam, based on said amount of defocus;
• preparing a plurality of said resist patterns by lithography while employing, for different resist patterns, different values of a particular lithographic factor as a parameter among the lithographic factors that contribute to the defocus of said pseudo-profile of the beam;
• conducting the measurement of the line width and the edge roughness for each of said resist patterns;
• calculating the amounts of defocus based on the line widths and edge roughnesses of the respective resist patterns as obtained with said different values of said particular lithographic factor;
• calculating the dependency of said amount of defocus on said particular lithographic factor;
• and
• optimizing said particular lithographic factor based on the calculated dependency.