Using hybrid ionized physical vapor deposition to control interface reaction during titanium deposition onto aluminum under-layer

For via structures landed on aluminum (Al) lines, ionized metal plasma (IMP) titanium (Ti) liner deposition can induce high via resistance as a result of the reaction between high energy Ti ions and the Al under-layer. The scale of the interface reaction is a function of the energy of the incoming Ti ions. A method to minimize the Ti/Al interface reaction is to introduce a thin protection layer over the Al under-layer prior to IMP Ti liner deposition. A convenient way to implement this method is to use a hybrid process, in which a Ti protection layer is first deposited in non-ionized mode prior to IMP Ti deposition. Hybrid ionized physical vapor deposition has been confirmed to be effective in minimizing the Ti/Al interface reaction during titanium deposition onto the aluminum under-layer.