Aberration monitoring toward wavefront matching with device patterns

Wavefront matching is a new technique for compensating uncontrollable aberr ation effects on a certain reticle design which involves moving controllabl e aberrations. Such a compensation concept is crucial for producing system- on-chip devices using photolithography. A high-precision wavefront monitor is an essential item for the wavefront matching. The resist-based aberratio n measurement technique based on the three-beam interference theory is a ca ndidate for monitoring. In the present work, the wavefront in the lithograp hy lens was driven by the lens controller, and then the slight change from the initial state was measured using the technique. For the experiment, a k rypton fluoride excimer laser scanner with a numerical aperture (NA) of 0.6 8 was used. The measurement results verified that the technique has suffici ent sensitivity to monitor the wavefront matching.