High-Precision Wafer Bonding Alignment Mark Using Moiré Fringes and Digital Grating.

This paper investigates a moiré-based mark for high-precision wafer bonding alignment. During alignment, the mark is combined with digital grating, which has the benefits of high precision and small size. A digital grating is superimposed on the mark to generate moiré fringes. By performing a phase calculation on the moiré fringe images corresponding to the upper and lower wafers, the relative offset of the upper and lower wafers can be accurately calculated. These moiré fringes are exceptionally stable, thereby enhancing the alignment stability. In this study, through practical experiments, we tested the rationality and practicability of the mark.