THE EFFECTS OF AL(111) CRYSTAL ORIENTATION ON ELECTROMIGRATION IN HALF-MICRON LAYERED AL INTERCONNECTS

A study has been done on the crystallographic effects of under-metal p lanes on Al(111) orientation in layered Al interconnects (Al/Ti, Al/Ti N/Ti), and the dominant factor for electromigration was clarified in t he region below a half-micron line width. It was found that Al(111) pr eferred orientation is strongly dependent on the crystal structure and process sequence of the under-metal, and universally determined by th e difference between the spacing of Al(111) plane and under-metal plan es. Moreover, it was found that the electromigration endurance tends t o improve in proportion to the degree of Al(111) preferred orientation . Therefore, the formation of an under-metal layer with an appropriate plane whose spacing is close to that of the Al(111) plane is the most significant criterion for the realization of highly oriented Al(111) planes and hence highly reliable ULSI interconnects.