AbstractDiffusion barrier characteristics of amorphous and polycrystalline electroless Co(W,P) layers (α-Co(W,P) and poly-Co(W,P)) to lead-free SnAgCu (SAC) solder were investigated via the liquid- and solid-state aging tests. In the sample containing α-Co(W,P) subjected to liquid-state aging at 250°C for 1 hr, the spallation of (Co,Cu)Sn3 intermetallic compound (IMC) into the solder and formation of a polycrystalline P-rich layer in between SAC and Co(W,P) were found. Further, the α-Co(W,P) transforms into polycrystalline structure embedded with tiny Co2P precipitates As to the sample containing α-Co(W,P) subjected to solid-state aging at 150°C up to 1000 hrs, a thick (Cu,Co)6Sn5 IMC resided in between SAC and Co(W,P) and the P-rich layer beneath IMCs was similarly seen. In the samples containing poly-Co(W,P) subjected to liquid-state aging, a mixture of (Co,Cu)Sn3 and (Co,Ag)Sn3 IMCs formed in between SAC and Co(W,P). An amorphous W-rich layer formed in between SAC and poly-Co(W,P). Similar interfacial morphology was observed in the samples subjected to the solid-state aging test. Analytical results indicated the electroless Co(W,P) is in essential a combined-type, i.e., sacrificial-type plus stuffed-type, diffusion barrier. However, the α-Co(W,P) is a better diffusion barrier for under bump metallurgy (UBM) applications in flip-chip (FC) bonding since it exhibits a lower Co consumption rate in comparison with poly-Co(W,P).
AbstractWe comparatively studied the formation of ultra thin Co silicides, Co2Si, CoSi and CoSi2, with/without a Ti-capped and Ti-mediated layer by using rapid thermal annealing in a N2 ambient. Four-point-probe sheet resistance measurements and plan-view electron diffraction were used to characterize the silicides as well as the epitaxial characteristics of CoSi2 with Si. We found that the formation of the Co silicides and their existing duration are strongly influenced by the presence of a Ti-capped and Ti-mediated layer. A Ti-capped layer promotes significantly CoSi formation but suppresses Co2Si, and delays CoSi2, which advantageously increases the silicidation-processing window. A Ti-mediated layer acting as a diffusion barrier to the supply of Co suppresses the formation of both Co2Si and CoSi but energetically favors directly forming CoSi2. Plan-view electron diffraction studies indicated that both a Ti-capped and Ti-mediated layer could be used to form ultra thin epitaxial CoSi2 silicide.
AbstractWe investigate the surface kinetics of Pt using the extended embedded-atom method, an extension of the embedded-atom method with additional degrees of freedom to include the nonbulk data from lower-coordinated systems as well as the bulk properties. The surface energies of the clean Pt (111) and Pt (100) surfaces are found to be 0.13 eV and 0.147 eV respectively, in excellent agreement with experiment. The Pt on Pt (111) adatom diffusion barrier is found to be 0.38 eV and predicted to be strongly strain-dependent, indicating that, in the compressive domain, adatoms are unstable and the diffusion barrier is lower; the nucleation occurs in the tensile domain. In addition, the dissociation barrier from the dimer configuration is found to be 0.82 eV. Therefore, we expect that atoms, once coalesced, are unlikely to dissociate into single adatoms. This essentially tells that by changing the applied strain, we can control the patterning of nanostructures on the metal surface.
METGLAS Alloy 2826 (Fe40Ni40P14B6) is a ferromagnetic, high permeability, nickel-iron metallic glass which, when appropriately annealed, yields a material similar to the higher nickel containing permalloys in magnetic properties. Alloy 2826 is a single phase, opaque metallic material with a glass-like structure obtained by a very rapid quench from the liquid state. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on forming and heat treating. Filing Code: Ni-235. Producer or source: Allied Chemical Corporation.