Lithographic system, and method of using the same to perform lithography

A method of using a lithographic system to perform lithography, the lithographic system including:

• an illuminator including a light source unit, a beam shaping unit, a diffuser unit, a light pipe unit and an exposure control unit, and configured to output a light beam from the light source unit to a reticle through the beam shaping unit, the diffuser unit, the light pipe unit and the exposure control unit, so that the reticle outputs a patterned light beam, the diffuser unit being mounted to an inlet end of the light pipe unit;
• and
• a projection apparatus including a projection lens assembly and a numerical aperture component, and configured to receive and project the patterned light beam onto a target wafer,
• the method comprising:
• performing, by the lithographic system, a first lithographic process on a first wafer that serves as the target wafer in the first lithographic process and that is coated with a first photoresist layer having a first photoresist thickness,
• wherein, in the first lithographic process, the numerical aperture component is set to have a first numerical aperture value that is not greater than a predetermined numerical aperture value, and the diffuser unit has an aperture set to a first diffuser aperture value;
• and
• performing, by the lithographic system, a second lithographic process on a second wafer that serves as the target wafer in the second lithographic process and that is coated with a second photoresist layer having a second photoresist thickness greater than the first photoresist thickness,
• wherein, in the second lithographic process, the numerical aperture component is set to have a second numerical aperture value that is not greater than the predetermined numerical aperture value, and the aperture of the diffuser unit is set to a second diffuser aperture value greater than the first diffuser aperture value.

A lithographic system, comprising:

• an illuminator that includes:
• a light source unit disposed to emit an initial light beam;
• a beam shaping unit disposed to receive and modify the initial light beam, thereby outputting a first modified light beam;
• a diffuser unit having an aperture that is adjustable, and disposed to receive and modify the first modified light beam, thereby outputting a second modified light beam;
• a light pipe unit disposed to receive and modify the second modified light beam, thereby outputting a third modified light beam, wherein the light pipe unit having an inlet end to which the diffuser unit is mounted;
• and
• an exposure control unit disposed to receive and modify the third modified light beam, thereby outputting a fourth modified light beam to a reticle;
• and
• a projection apparatus that includes:
• a projection lens assembly disposed to receive and modify a patterned light beam that is outputted by the reticle modifying the fourth modified light beam, thereby outputting a fifth modified light beam;
• and
• a numerical aperture component having a numerical aperture, and operable to permit passage of the fifth modified light beam to be projected onto a wafer.