Selective and Superconformal Molybdenum Growth Strategies for Advanced Metallization

The resistivity increase with decreasing width of interconnect lines is a major challenge for the continued downscaling of integrated circuits. As we inflect to Molybdenum (Mo)-based metallization solutions in our customer integration schemes — and away from Cobalt(Co), Ruthenium (Ru), and tungsten(W) — precise control over the barrierless Mo grain size distribution is critical. Due to its oxophilicity (i.e., its high affinity to oxidize to MoOx), Mo is a challenging metal from both a processing and precursor design point of view. Herein we leverage the various deposition and etching properties of a MoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf>X<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</inf>(L)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> precursor and its applications in various metallization schemes. Clean and bottom-up (selective) growth profiles as well as examples of superconformal growth using MoO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf>X<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</inf>(L)<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf>-based precursors is shown through various analyses such as precession electron diffraction (PED) imaging. We obtain single-grain Mo in most (>90%) vias of our Lam-internal test vehicle structures due to the lack of grain boundary formation, which tends to form if there are significant Mo precursor and feature sidewall interactions. Our advanced barrierless Mo metallization schemes are highly effective and will continue to be applicable to advanced logic devices as they scale below the 2nm node.