OVERLAY ALIGNMENT MARK AND ALIGNMENT METHOD FOR THE FABRICATION OF TRENCH-CAPACITOR DRAM DEVICES

摘要

A small-size (w0.5 micrometers) alignment mark in combination with a “k1 process” is proposed, which is particularly suited for the fabrication of trench-capacitor DRAM devices which requires highly accurate AA-DT and GC-DT overlay alignment. The “k1 process” is utilized to etch away polysilicon studded in the alignment mark trenches and to refresh the trench profile, thereby improving overlay alignment accuracy and precision.