Improvement of Patterning Homogeneity in a Field of Projection Exposure System Using a Gradient-Index Lens Array

Abstract

Pattern width homogeneity in an exposure field of gradient-index (GRIN) lens array was greatly improved by changing the sub-scan method for averaging the pattern widths. By investigating the pattern width distribution in the exposure field, it was clarified that the parts, where the printed patterns were degraded and pattern widths were notably changed, appeared as striped lines. It was supposed that the striped abnormal pattern-width change was caused by the extra exposures for the times when the sub-scan stage was stopped at both the sub-scan ends for turning the scan direction. For this reason, sub-scan length was vastly extended, and the sub-scan stage was turned at the both ends after all the patterns on a reticle passed over the actually used parts of a GRIN lens array. By this method, no patterns were exposed and projected on a wafer while the sub-scan stage was stopped for turning at the both ends. As a result, 15-µm L&S patterns were almost homogeneously printed in the exposure field within a variation range of ±6%.

Application of projection lithography using a gradient-index lens array and wet etching to texturing for control of the hydrophobic properties of stainless-steel plates

“…A scan-projection exposure system using a gradient-index lens array as a projection lens was adopted as a tool for lithography. [30][31][32][33] The system was developed in previous research for printing patterns larger than 15 μm in a large field. In the usage to be investigated here, it was supposed that large-field patterning was required.…”

Improvement of Hydrophobic Property of Stainless-Steel Plates by Forming Lens-Like Protrusions Similar to Oxalis Leaf Surfaces

“…To form similar configurations on stainless-steel plates, scan-projection lithography using a gradient-index lens array as a projection lens [11] and wet chemical etching in ferric chloride (FeCl3) were adopted. The peculiar lithography was used considering the suitability for the application.…”