First demonstration of Two Metal Level Semi-damascene Interconnects with Fully Self-aligned Vias at 18MP.

In this paper we demonstrate the functionality of a semi-damascene integration scheme with fully self-aligned vias (FSAV) for interconnects from 26 to 18nm metal pitch (MP), fabricated on 300mm wafers. We have developed a novel integration flow, using the principle of subtractive etching of Ru, on 2 subsequent metal levels. Using structures with programmed overlay shift, we demonstrate the functionality of a fully self-aligned via process which results in working devices with placement errors of up to 5nm. Furthermore, we show via-to-line breakdown field > 9MV/cm, confirming FSAV.