Enzymatic ligation of discrete nanoparticle-DNA conjugates creates nanoparticle dimer and trimer structures in which the nanoparticles are linked by single-stranded DNA, rather than doublestranded DNA as in previous experiments. Ligation is verified by agarose gel and small-angle X-ray scattering. This capability is utilized in two ways: first to create a new class of multiparticle building blocks for nanoscale self-assembly; second to develop a system which can amplify a population of discrete nanoparticle assemblies.

In modern Cu interconnections in microelectronics, weak adhesion between the chemical-mechanical polished copper surface and the dielectric capping material can lead to rapid electromigration of Cu and early failure of the wiring. A self-aligned chemical vapor deposition ͑CVD͒ Mn capping process is introduced to strengthen the interface between Cu and dielectric insulators without increasing the resistivity of Cu. In this CVD process, a vapor mixture of Mn precursor and molecular hydrogen deposits Mn selectively on copper and not at all on the adjacent, previously deactivated surfaces of insulators. Deactivation of the insulator surfaces is accomplished by exposure to vapors containing reactive alkylsilyl groups. The presence of Mn at the Cu/insulator interface greatly increases the strength of the bonding between Cu and the insulator. The debonding energy increases approximately linearly with the amount of Mn at the interface, up to values so large that the interface could not be broken apart. This Mn-enhanced binding strength of Cu to insulators is observed for all insulators tested, including plasma-enhanced chemical vapor deposited Si 3 N 4 , SiCNOH, SiO 2 , and low-k SiCOH, as well as thermal SiO 2 and atomic-layer-deposited SiO 2. This selective CVD Mn capping process should increase the lifetime of advanced copper interconnections.

We present a process for the void-free filling of sub-100 nm trenches with copper or copper-manganese alloy by chemical vapor deposition (CVD). Conformally deposited manganese nitride serves as an underlayer that initially chemisorbs iodine. CVD of copper or copper-manganese alloy releases the adsorbed iodine atoms from the surface of the manganese nitride, allowing iodine to act as a surfactant catalyst floating on the surface of the growing copper layer. The iodine increases the growth rate of the copper and manganese by an order of magnitude. As the iodine concentrates near the narrowing bottoms of features, void-free, bottom-up filling of CVD of pure copper or copper-manganese alloy is achieved in trenches narrower than 30 nm with aspect ratios up to at least 5:1. The manganese nitride films also show barrier properties against copper diffusion and enhance adhesion between copper and dielectric insulators. During post-deposition annealing, manganese in the alloy diffuses out from copper through the grain boundaries and forms a self-aligned layer that further improves adhesion and barrier properties at the copper/insulator interface. This process provides nanoscale interconnects for microelectronic devices with higher speeds and longer lifetimes.

Through-silicon vias (TSV) will speed up interconnections between chips. Manufacturable and cost-effective TSVs will allow faster computer systems. In this paper, we report the successful formation of seed layers for plating copper TSVs with aspect ratios greater than 25:1. Following the rapid atomic layer deposition (ALD) of a conformal insulating layer of silica inside the silicon vias, manganese nitride (Mn 4 N) is deposited conformally on the silica surface by chemical vapor deposition (CVD). Mn 4 N forms an effective copper diffusion barrier and provides strong adhesion between the silica and the subsequently-deposited copper. Conformal copper or copper-manganese alloy films are then deposited by an iodine-catalyzed direct-liquid-injection (DLI) CVD process. Diffusion of manganese during post-deposition annealing further enhances the barrier and adhesion properties at the copper/dielectric interface.