Optical method and apparatus for quickly realizing precise calibration of lithography system

A method for fast precise optical calibration on a photolithography system, comprising:

• determining a mathematical equation for a spot width corresponding to a point light source based on distribution of field strength generated by the point light source at an exit plane of a focusing element, wherein the mathematical equation reflects a relationship between the spot width and a parameter for exposing a photoresist;
• determining, based on the mathematical equation, a first correspondence between the spot width and the parameter for exposing the photoresist;
• determining a first spot-width dataset for the point light source based on an optical microscopic image of a spot-mapping pattern on a surface of the photoresist, wherein spot widths in the first spot-width dataset is for optical microscopy;
• determining, based on the first spot-width dataset, a second correspondence between the spot width and the parameter for exposing the photoresist, wherein the second correspondence is recorded in the first spot-width dataset;
• and
• determining the first correspondence as a means for determining the parameter for exposing the photoresist, when the first correspondence and the second correspondence meet a preset condition,
• wherein the focusing element comprises a bowtie nano-aperture structure, and
• determining the mathematical equation for the spot width corresponding to the point light source based on the distribution of the field strength generated by the point light source at the exit plane of the focusing element comprises:
• acquiring distribution of field strength of the point light source after light emitted by the point light source passes through the bowtie nano-aperture structure;
• and
• determining the mathematical equation based on the distribution of the field strength of the point light source.