QUANTITATIVE MEASUREMENT OF NODULE FORMATION IN W-TI SPUTTERING

Titanium-tungsten alloys have been used as a diffusion barrier between Si substrates and Al-based interconnect metallization for more than t wo decades. Due to the increasing complexity of integrated circuits, t he primary concern has been focused on the reduction of particles duri ng sputtering. Flaking of the redeposited nodules on the target surfac e was suspected to be one of the particulate sources. To control the n odule formation, a fundamental knowledge of the nodule formation mecha nism is required. In this study, the influence of target properties an d sputtering parameters on nodule formation in sputtering targets of t ungsten with 10 and 15 wt % titanium was investigated. The amount and life of the nodules as a function of target life was determined. A par abolic relation showed a saturated nodule size with increased sputteri ng life. The existence of fractured nodules confirms the nodules to be the particulate source. (C) 1998 American Vacuum Society. [S0734-2101 (98)09604-3].