• Polymer(Korea)
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• v.31 no.3
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• pp.184-188
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• 2007

Monodisperse PMMA/HDDA polymer particles were coated via electroless Ni plating using sodium hypophosphite as a reducing agent in an acidic environment. In this study, the effects of 1) the pretreatment conditions, 2) the plating temperature, 3) the plating pH, and 4) the initial pH, control of plating bath on the variation of plating rate, surface state of plated particles and plating reproducibility were investigated. It was observed that every pretreatment steps, especially conditioning and acceleration step, were very important for obtaining uniform Ni plating and the plating rate was increased with the increase of plating temperature and pH. Moreover, the initial pH control of plating bath was critical for the plating reproducibility.

• Korean Journal of Materials Research
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• v.19 no.2
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• pp.61-67
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• 2009

Electrolessly deposited Co (Re,P) was investigated as a possible capping layer for Cu wires. 50 nm Co (Re,P) films were deposited on Cu/Ti-coated silicon wafers which acted as a catalytic seed and an adhesion layer, respectively. To obtain the optimized bath composition, electroless deposition was studied through an electrochemical approach via a linear sweep voltammetry analysis. The results of using this method showed that the best deposition conditions were a $CoSO_4$ concentration of 0.082 mol/l, a solution pH of 9, a $KReO_4$ concentration of 0.0003 mol/l and sodium hypophosphite concentration of 0.1 mol/L at $80^{\circ}C$. The thermal stability of the Co (Re,P) layer as a barrier preventing Cu was evaluated using Auger electron spectroscopy and a Scanning calorimeter. The measurement results showed that Re impurities stabilized the h.c.p. phase up to $550^{\circ}C$ and that the Co (Re,P) film efficiently blocked Cu diffusion under an annealing temperature of $400^{\circ}C$ for 1hr. The good barrier properties that were observed can be explained by the nano-sized grains along with the blocking effect of the impurities at the fast diffusion path of the grain boundaries. The transformation temperature from the amorphous to crystal structure is increased by doping the Re.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.97-106
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• 2000

In these respects the purpose of this research is manufacturing Co-W-P alloy thin film on the corning glass 2948 by electroless plating method using $NaH_2PO_2H_2O$ (sodium hypophosphite) as a reductant, and analyzing deposition rate, alloy composition, microstructure, and magnetic characteristics at various pH's and temperatures. For Co-P alloy thin film, the reductive deposition reaction occurred only in basic condition, not in acidic condition. The deposition rate increased as the pH and temperature increased, and the optimum condition was found at the pH of 10 and the temperature of 8$0^{\circ}C$. Also magnetic characteristics was found to be most excellent at the pH of 9 and the temperature of 7$0^{\circ}C$, resulting in the coercive force of 870Oe and the squareness of 0.78. At this condition, the contents of P was 2.54% and the thickness of the film was 0.216$\mu\textrm{m}$. For crystal orientation, we could not observe fcc for $\beta$-Co. On the other hand, (1010), (0002), (1011) orientation of hcp for $\alpha$-Co was observed. We could confirm the formation of longitudinal magnetization from dominant (1010) and (1011) orientation of Co-P alloy. For Co-W-P alloy thin film, coercive force was 500Oe and squareness was 0.6. For crystal orientation, (0002) orientation of $\alpha$-Co was dominatly found. Then we could confirm the formation of perpendicular magnetization. The content of P was constant at 0.8$\pm$0.2% and the content of W increased as the concentration of Na$_2$WO$_4$increased. When the concentration of Na$_2$WO$_4$was 0.1mol/L, the composition of W was 20%. We observed the changes of magnetic characteristics and microstructure of thin film depositions of Co-W-P by the heat treatment. For heat treatment, the temperature was increased step by step to 10$0^{\circ}C$, 20$0^{\circ}C$, 30$0^{\circ}C$, and 40$0^{\circ}C$ and it took 1 hour at each step in the reductive condition of hydrogen gas. By the heat treatment, flatness of surface was improved, but there were no changes on the magnetic characteristics and the microstructures.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.274-281
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• 1999

Usually sputtering and electroless plating methods were used for manufacturing metal-alloy thin film magnetic memory devices. Since electroless plating method has many merits in mass production and product variety com­pared to sputtering method, many researches about electroless plating have been performed in the United State of America and Japan. However, electroless plating method has not been studied frequently in Korea. In these respects the purpose of this research is manufacturing Co-Mn-P alloy thin film on the corning glass 2948 by electroless plating method using sodium hypophosphite as a reductant, and analyzing deposition rate, alloy composition, microstructure, and magnetic characteristics at various pH's and temperatures. For Co-P alloy thin film, the reductive deposition reaction 0$\alpha$urred only in basic condition, not in acidic condition. The deposition rate increased as the pH and temperature increased, and the optimum condition was found at the pH of 10 and the temperature of $80^{\circ}C$. Also magnetic charac­teristics was found to be most excellent at the pH of 9 and the temperature of $70^{\circ}C$, resulting in the coercive force of 8700e and the squareness of 0.78. At this condition, the contents of P was 2.54% and the thickness of the film was $0.216\mu\textrm{m}$. For crystal orientation, we could not observe fcc for $\beta$-Co. On the other hand,(1010), (0002), (1011) orientation of hcp for a-Co was observed. We could confirm the formation of longitudinal magnetization from dominant (1010) and (1011) orientation of Co-P alloy. For Co-Mn-P alloy deposition, coercive force was about 1000e more than that of Co P alloy, but squareness had no difference. For crystal orientation, (l01O) and (lOll) orientation of $\alpha$-Co was dominant as same as that of Co- P alloy. Likewise we could confirm the formation of longitudinal magnetization.