Method and apparatus for controlling light intensity and for exposing a semiconductor substrate

A method of exposing a substrate, comprising:

• irradiating in a first exposure process a first illumination having a first intensity distribution onto the substrate through a photo mask to form a first pattern on the substrate;
• obtaining a critical dimension distribution of the first pattern;
• calculating a second intensity distribution of the first illumination based on a relation between the first intensity distribution and the critical dimension distribution, the second intensity distribution being used for forming a second pattern having uniform critical dimensions on the substrate;
• converting the first illumination to a second illumination having the second intensity distribution;
• and
• forming in a second exposure process the second pattern on the substrate using the second illumination.

An apparatus for controlling a light intensity, comprising:

• an optical unit for selectively controlling an intensity distribution of a light according to regions of a mask pattern, wherein the light is irradiated onto a photo mask having the mask pattern;
• a detecting unit for detecting a critical dimension distribution of a first pattern on a substrate, the first pattern being formed using a first illumination having a first intensity distribution responsive to the photo mask;
• a calculating unit for calculating a second intensity distribution based on a relation between the first intensity distribution and the critical dimension distribution, the second intensity distribution being used for forming a second pattern having uniform critical dimensions on the substrate;
• and
• a controlling unit for controlling the optical unit to convert the first illumination into a second illumination having the second intensity distribution.

An apparatus for exposing a semiconductor substrate, comprising:

• a light source for generating an illumination for irradiating a photo mask having a mask pattern;
• an optical unit for selectively controlling an intensity distribution of the illumination according to regions of the mask pattern;
• a detecting unit for detecting a critical dimension distribution of a first pattern on a substrate, the first pattern being formed using a first illumination having a first intensity distribution;
• a calculating unit for calculating a second intensity distribution of the first illumination based on a relation between the first intensity distribution and the critical dimension distribution, the second intensity distribution being used for forming a second pattern having uniform critical dimensions on the substrate;
• and
• a controlling unit for controlling the optical unit to convert the first illumination into a second illumination having the second intensity distribution.