An electroplated Ni–P film with about 0.9 wt% co-deposited phosphorus was obtained using a sulfamic-acid-type Ni electroplating solution containing 0.05 mol/dm3 of phosphoric acid for improvement of corrosion resistance. However, crack-formation-deposited Ni–P films were often observed under operation at pH 4. This problem was resolved by operation at pH of 2.5. Furthermore, we were able to achieve crack-free Ni-P deposition with high current density. Moreover, bright Ni–P films were obtained using acetic acid or formic acid as the organic acid. The phosphorus content might be controllable by changing the phosphorous acid concentration. Crack-free Ni–P films with about 4.0 wt% co-deposited phosphorus were formed by addition of 0.4 mol/dm3 phosphorous acid and 0.2 mol/dm3 acetic acid as the organic acids. Next, we plated various Ni(3 μm) and Au–Co(0.03 μm) films on test substrates for which the corrosion resistance of the resulting electroplated Au–Co/Ni films were examined. The electroplated Au–Co/Ni–P films were superior corrosion-resistant electroplated Ni films. Their corrosion resistance improved with the increase of phosphorus content.
This study examined dry removal of CO2 laser via bottom residue using 60 Hz nonequilibrium atmospheric pressure plasma with trifluoromethyl trifluorovinyl ether (C3F6O) mixing gas. (‘Removal of residue’ is defined as ‘de-smear’ in this paper.) Existing wet de-smear processing with KMnO4 will have a technical limitation for fine via that diameter is 50 μm or less. A dry process technology that allows fine via de-smearing is necessary for fine-pitch printed circuit board manufacturing. Results show that via bottom residue was de-smeared successfully using the plasma treatment with 2.0% of C3F6O mixing to argon gas. For tetrafluoromethane (CF4), 10.0% mixing was necessary for the plasma dry de-smearing. The global warming potential of C3F6O is close to zero as 4.57 × 10−4, so the result of de-smearing with 2.0% of C3F6O mixing ratio (the mixing ratio is 1/5 of CF4) gives us high expectations of conducting a low environmental impact practical manufacturing process. The optical emission spectra of the plasma were measured, and found that the intensity of CF2 radical and CF3 radical correspond to the result of the via bottom residual ratio. It reveals that CF2 radical and CF3 radical are active species to volatilize SiO2 filler residue. The gas molecule of C3F6O, which includes the fluoroalkyl ether group, is easily dissociated with low energy electrons. The 60 Hz nonequilibrium atmospheric pressure plasma has high density of low-temperature (energy) electrons. Therefore, the via bottom residue was de-smeared successfully using the atmospheric pressure plasma with a low mixing ratio of C3F6O.
Correlation between the physical and chemical properties of the reaction products and dissolution behavior of copper in Cu-CMP slurry containing hydrogen peroxide was studied. The solubility behavior of the copper was evaluated for corrosion current density using Tafel plots with a rotating electrode that had an original load addition function. The physical and chemical properties of the product were evaluated using AES, XPS, and a nanoindenter. Numerous reaction products with low hardness were generated under the condition with a large corrosion current density under the load. With high corrosion current density, the reaction products consisted of Cu and the additives as the main constituents. In contrast, when the corrosion current density was low, copper oxide predominated. These results indicate that controlling the oxide generation rate and the reactive generation rate of the additive is important for increasing the rate and enabling both to coexist smoothly. Regarding enabling the coexistence of speed-up and flattening, the proportional control of the oxide generation rate and the generation rate of the reactant with the additive is important.
In an earlier study, PVD hard coatings with micropores formed by polymer microparticles were confirmed to have superior tribological properties. However, the polymer microparticles that were used were too expensive to put the process to practical use. Therefore, in this work, fabrication of copper microparticles on Ni-plated SKD11 substrate by copper deposition and dissolution in acid copper sulfate bath was investigated for use instead of polymer microparticles. The number of copper microparticles by nucleation on the Ni plated substrate by square-wave current for 1 s occurred only at the current density of a wave higher than 0.1 A/dm2. Their number increased with current density from ca. 105/mm2 to more than 108/mm2. However, by continuing electrolysis at lower current density of ca. −0.05 A/dm2 after the square-wave current pulse, only copper microparticles, as many as 104/mm2, grew exclusively. The number of them were constant independent of the initial current density. Furthermore, by application of anodic current, non-growth microparticles dissolved to disappear and the growing particles became globular. Using the Ni-plated SKD11 substrate on which Cu microparticles were formed using this method, a CrN hard coating with micropores was achieved by cathodic vacuum arc ion plating.