LIFT-OFF METALLIZATION OF SPUTTERED AL-ALLOY FILMS

A lift-off technique of sputtered Al alloy films for interconnection has been investigated. The results are summarized as follows: (i) Aluminum alloy films exceeding photoresist in thickness are successfully metallized without reduction in pattern width; (ii) the slope of the side walls of metallized Al alloy patterns is contgrolled by Ar pressure during sputtering; and (iii) for narrow metal lines, metal thickness decreases with decreasing line width. These results are qualitatively explained by considering the sputtered Al alloy film structure and the shadowing effect of deposition at the photoresist pattern step. It is shown that this technique is applicable for fabrication of various interconnections in large scale integrated circuits.