Multiple exposure method

An exposure method for performing an exposure of a resist in relation to a desired pattern by use of a projection optical system, said method comprising:

• a first step for applying a first exposure amount distribution on the basis of a dual-beam interference exposure process;
• and
• a second step for applying a second exposure amount distribution on the basis of an exposure process using a mask having a pattern being analogous to the desired pattern, said second exposure amount distribution including a first portion of a small exposure amount not being zero and a second portion of a large exposure amount;
• wherein an exposure process for a portion of the desired pattern is performed on the basis of superposition of a portion of the first exposure amount distribution and the first portion of the second exposure amount distribution, while an exposure process for the remaining portion of the desired pattern is performed on the basis of the second portion of the second exposure amount distribution as superposed with another portion of the first exposure amount distribution;
• wherein the numerical aperture of the projection optical system in the second step is made smaller than that of the projection optical system in the first step.

An exposure method for performing an exposure of a resist in relation to a desired pattern by use of a projection optical system, said method comprising:

• a first step for applying a first exposure amount distribution having an exposure amount not greater than an exposure threshold value of the resist, on the basis of a dual-beam interference exposure process using a first mask having at least one of a phase shifter and a light blocking portion;
• and
• a second step for applying a second exposure amount distribution on the basis of an exposure process using a second mask having a pattern being analogous to the desired pattern, said second exposure amount distribution including a first portion of an exposure amount not being zero but being not greater than the exposure threshold value, and a second portion of an exposure amount not less than the exposure threshold value;
• wherein an exposure process for a portion of the desired pattern is performed on the basis of superposition of a portion of the first exposure amount distribution and the first portion of the second exposure amount distribution, while an exposure process for the remaining portion of the desired pattern is performed on the basis of the second portion of the second exposure amount distribution as superposed with another portion of the first exposure amount distribution;
• wherein the numerical aperture of the projection optical system in the second step is made smaller than that of projection optical system in the first step.

An exposure method for performing an exposure of a resist in relation to a desired pattern by use of a projection optical system, said method comprising:

• a first step for applying a first exposure amount distribution on the basis of a periodic pattern exposure process;
• and
• a second step for applying a second exposure amount distribution on the basis of an exposure process using a mask having a pattern being analogous to the desired pattern, said second exposure amount distribution including a first portion of a small exposure amount not being zero and a second portion of a large exposure amount;
• wherein an exposure process for a portion of the desired pattern is performed on the basis of superposition of a portion of the first exposure amount distribution and the first portion of the second exposure amount distribution, while an exposure process for the remaining portion of the desired pattern is performed on the basis of the second portion of the second exposure amount distribution as superposed with another portion of the first exposure amount distribution;
• wherein the numerical aperture of the projection optical system in the second step is made smaller than that of the projection optical system in the first step.

An exposure method for performing an exposure of a resist in relation to a desired pattern by use of a projection optical system, said method comprising:

• a first step for applying a first exposure amount distribution having an exposure amount not greater than an exposure threshold value of the resist, on the basis of a periodic pattern exposure process using a first mask having at least one of a phase shifter and a light blocking portion;
• and
• a second step for applying a second exposure amount distribution on the basis of an exposure process using a second mask having a pattern being analogous to the desired pattern, said second exposure amount distribution including a first portion of an exposure amount not being zero but being not greater than the exposure threshold value, and a second portion of an exposure amount not less than the exposure threshold value;
• wherein an exposure process for a portion of the desired pattern is performed on the basis of superposition of a portion of the first exposure amount distribution and the first portion of the second exposure amount distribution, while an exposure process for the remaining portion of the desired pattern is performed on the basis of the second portion of the second exposure amount distribution as superposed with another portion of the first exposure amount distribution;
• wherein the numerical aperture of the projection optical system in the second step is made smaller than that of projection optical system in the first step.