AlCu PVD (Physical Vapor Deposition) induced overlay shift has been a critical concern for non-damascene metallization process to tackle with the ever decreasing overlay tolerances. In this study, a new approach was demonstrated to effectively eliminate the AlCu PVD induced overlay shift. With measuring the metal-to-contact registration before the metal deposition and feeding forward the values for metal-to-contact overlay compensation at the metal photo process, the metal-induced shift can be optimally managed. Besides, an investigation was also carried out to figure out the suitable measurement target with least sensitive to process parameter variations at after contact etch, after contact W CMP and after metal etch. As a consequence, the conventional wide-trench overlay target has been identified to be the more susceptible to the process variation and easily results in measurement reading error. Compared to the conventional wide-trench target, a 0.2um width narrow trench target performed the better mark integrity for our feed-forward compensation approach. Finally, the feed-forward compensation in combination with narrow width overlay mark has demonstrated its effectiveness on managing the AlCu-PVD induced overlay shift.

Date Published: 5 April 2007
PDF: 8 pages
Proc. SPIE 6518, Metrology, Inspection, and Process Control for Microlithography XXI, 651845 (5 April 2007); doi: 10.1117/12.706758

Published in SPIE Proceedings Vol. 6518:
Metrology, Inspection, and Process Control for Microlithography XXI
Chas N. Archie, Editor(s)