Ab initio molecular orbital (MO) and density functional theory (DFT) calculations were applied to zinc clusters comprising 2-192 atoms. The minimum bonding length, average binding energy, and electron population of the 4p orbital (N4p) were evaluated as a function of the number of atoms (n) after optimization of the cluster structure. The clusters show a drastic transition in their properties from molecular to clusters at around n=4, and gradually exhibit bulk properties with increasing n. Polarization of the clusters' electric charge was also predicted—negative charging inside the cluster and positive charging at the surface—attributable to nonuniform distribution of electrons belonging to the orbits of respective atoms. The highest occupied molecular orbital - lowest unoccupied molecular orbital (HOMO-LUMO) transition energy gap with changing n, the relation between the N4p value, the cluster stabilization energy, and the influence of defects in the crystalline N4p are also discussed.
This report describes a new process for ULSI minute copper-wiring formation. It relies on microcontact printing [μCP] of polyethylene glycol bis(1,2,3-benzotriazolylether) [PBTA]—synthesized from polyethylene glycol and benzotriazole—to the surface of copper seed layer, with preferential copper electrodeposition in PBTA-free regions (contact hole and trench) using an acid copper sulfate bath. The copper electrodeposition was done using an insoluble anode in the basic bath without additives. The microcontact printed PBTA on the copper seed-layer surface strongly inhibits copper electrodeposition. Using this process, because of the effect of site-selective printing of PBTA, a minute contact hole can be filled completely with copper without causing voids and seams.
Nanometer-scale mechanical properties of extremely thin DLC films deposited using filtered cathodic vacuum arc (FCVA) and electron cyclotron resonance plasma chemical vapor deposition (ECR-CVD) methods were evaluated. Auger electron spectroscopy (AES) revealed these DLC films' thickness and composition. Results showed that the obtained DLC films' thickness nearly corresponds to the set thickness. Nanoindentation hardness and nanowear resistance of the DLC films were investigated using atomic force microscopy (AFM). The nanoindentation hardness of 100-nm-thick DLC films deposited using FCVA and ECR-CVD were 57 GPa and 25 GPa, respectively, as evaluated at 40 μN load. The difference of nanoindentation curves of 5- and 2-nm-thick DLC films deposited using FCVA and ECR-CVD methods is only slightly detectable. It is difficult to evaluate the ultrathin DLC films' hardness using a nanoindentation test of several nanometers' thickness. In contrast, mechanical properties of the extremely thin DLC films can be clarified using nanowear testing with AFM. Wear depths of 100-, 5-, 2-nm-thick FCVA-DLC films are all less than 1 nm: extremely shallow. Especially, the wear depth of 100-nm-thick FCVA-DLC film is nearly 0.1 nm, even at 30 μN load. However, the wear depths of 100-, 5-, 2-nm-thick ECR-CVD-DLC films are greater than those of FCVA-DLC films. These results underscore the excellent wear resistance of extremely thin FCVA-DLC films.