Atomic and molecular layer activation of dielectric surfaces

Strong interaction between the material deposit and substrate is critical to stable deposits and interfaces. The work presented here focuses on the surface activation of dielectric surfaces and oxidized metal surfaces to promote the chemisorption of palladium (II) hexafluoroacetylacetonate (PdII (hfac)₂). The goal is to develop reliable, robust metallization protocols, which enable strong interactions between the metal and substrate.; SiO₂, air exposed Ta, Trikon, and SiLK were activated with sulfur or phosphorus. Two types of activations were developed; one based on self-assembled chemistry, and the other a plasma-assisted process. Activation of the surface using self-assembly techniques was carried out using mercaptan-terminated silane and tetrasulfide silane. The resulting films were characterized by variable angle spectroscopic ellipsometry, contact angle goniometry, and X-ray photoelectron spectroscopy. Tetrasulfide silane sources films exhibit self-limiting behavior, even in the presence of water vapor; whereas mercaptan-terminated silane sourced films tend to be thicker. The surface activations using atomic layers of sulfur and phosphorus were carried out in a rf plasma chamber using hydrogen sulfide and phosphine sources, respectively. The activations were studied as functions of rf power, system pressure, and substrate material. Results show that higher rf powers and lower system pressures promote greater surface coverages by sulfur with a reduced oxidation state. The activated dielectrics show evidence of PdII(hfac)₂ chemisorption, in contrast to non-activated surfaces. The binding energy shift of the Pd3d _5/2 XPS peak towards elemental Pd provides evidence for the dissociative chemisorption of PdII(hfac)₂. The extent of dissociation depends on the substrate temperature and the activation method used.; The conclusions of the work presented here have implications for metallization using highly polarizable transition metals. Specifically, it can be applied to the atomic layer and chemical vapor deposition of Pd. Another potential benefit is the activation of dielectric and oxidized metal surfaces for other deposition techniques; for example, to promote the chemisorption of copper ions from solution during electrochemical deposition of Cu.