Alignment error evaluation of the dial pattern

Abstract

To achieve smooth etched sidewall surface at minimal time expense and reduce undercut etching are basic disciplines of the task of accurate alignment. When aligning etch-masks to [110] crystal orientation on a [100] Si wafer, a consideration is proposed by Schroder who uses a dial pattern for pre-etching to determine [110] crystal orientation. But that performance depends strongly on the resolution of the mask pattern generator. In this paper, we analyse Schroder's method by mathematical modeling and computer simulation. Finally, we propose an improvement for the Schroder limitation according to our analytic results.