Aberration measurement of photolithographic lenses by use of hybrid diffractive photomasks.
In optical lithography the degradation of image quality due to aberrations present in the exposure tool is a serious problem. Therefore it is desirable to establish a reliable aberration measurement procedure based on the analysis of printed images in the photoresist. We present what is to our knowledge a new method for characterizing the aberrations of an exposure tool using a hybrid diffractive photomask. By utilizing each different impact on the aberrated image from each diffracted illumination, we were able to extract the aberration present in the stepper system. We experimentally verified this method with a G-line stepper and verified its spherical aberration astigmatism.
Sung
Jinwon
J
School of Optics, CREOL, University of Central Florida, P.O. Box 162700, 4000 Central Florida Boulevard, Orlando, Florida 32816-2700, USA.
Pitchumani
Mahesh
M
Johnson
Eric G
EG