The hydrogenated diamond-like carbon (DLCH) film with 1-µm thickness is deposited by direct hydrocarbon gas ion beam method on silicon wafer and annealed at 400 • C. Detailed Raman spectra feature are fitted from nine sets of different peak fitting functions, including Gaussian, Lorentzian and Breit-Wigner-Fano (BWF) functions. These fitting results obtained from a two-peak combination show some specific variances on the G peak position, FWHM G and I D /I G ratio for as-deposited and as-annealed DLCH films. The most popular two-peak fitting method with full Gaussian function tends to exhibit a higher ratio of the G peak position shift and higher I D /I G ratio than others fitting methods, the drastic difference among the most popular G (G) & G (D) and B (G) & L (D) schemes also have brought out in I D /I G ratio. However, for a more complex four-peak Gaussian function fitting Raman spectra, the I D /I G ratio is close to that of a two-peak fitting function with a mixture functions of BWF (G) and L (D). Furthermore, a series of systematic peak fitting procedures and comparisons of Raman spectra have been discussed in this study.
The Cu pillar is a thick underbump metallurgy (UBM) structure developed to alleviate current crowding in a flip-chip solder joint under operating conditions. We present in this work an examination of the electromigration reliability and morphologies of Cu pillar flip-chip solder joints formed by joining Ti/Cu/Ni UBM with largely elongated $62 lm Cu onto Cu substrate pad metallization using the Sn-3Ag-0.5Cu solder alloy. Three test conditions that controlled average current densities in solder joints and ambient temperatures were considered: 10 kA/cm 2 at 150°C, 10 kA/cm 2 at 160°C, and 15 kA/cm 2 at 125°C. Electromigration reliability of this particular solder joint turns out to be greatly enhanced compared to a conventional solder joint with a thinfilm-stack UBM. Cross-sectional examinations of solder joints upon failure indicate that cracks formed in (Cu,Ni) 6 Sn 5 or Cu 6 Sn 5 intermetallic compounds (IMCs) near the cathode side of the solder joint. Moreover, the $52-lm-thick Sn-Ag-Cu solder after long-term current stressing has turned into a combination of $80% Cu-Ni-Sn IMC and $20% Sn-rich phases, which appeared in the form of large aggregates that in general were distributed on the cathode side of the solder joint.
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