Using a customized diffusion bonder, we executed diffusion bonding for ring shaped white gold and red gold samples (inner, outer diameter, and thickness were 15.7, 18.7, and 3.0 mm, respectively) at a temperature of 780 °C and applied pressure of 2300 N in a vacuum of 5 × 10−2 torr for 180 seconds. Optical microscopy, field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to investigate the microstructure and compositional changes. The mechanical properties were confirmed by Vickers hardness and shear strength tests. Optical microscopy and FE-SEM confirmed the uniform bonding interface, which was without defects such as micro pores. EDS mapping analysis confirmed that each gold alloy was 14K with the intended composition; Ni and Cu was included as coloring metals in the white and red gold alloys, respectively. The effective diffusion coefficient was estimated based on EDS line scanning. Individual values of Ni and Cu were 5.0 × 10−8 cm2/s and 8.9 × 10−8 cm2/s, respectively. These values were as large as those of the melting points due to the accelerated diffusion in this customized diffusion bonder. Vickers hardness results showed that the hardness values of white gold and red gold were 127.83 and 103.04, respectively, due to solid solution strengthening. In addition, the value at the interface indicated no formation of intermetallic compound around the bonding interface. From the shear strength test, the sample was found not to be destroyed at up to 100,000 gf due to the high bonding strength. Therefore, these results confirm the successful diffusion bonding of 14K white-red golds with a diffusion bonder at a low temperature of 780 °C and a short processing time of 180 seconds.

In this study, we fabricated Nd2Fe14B hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of Nd2Fe14B. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentra- tions of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to con- trol the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of Nd2Fe14B phase and magnetic properties was investigated.

In the present study, we systematically investigated the effect of Mn addition on nitrogenation behavior and magnetic properties of Sm-Fe powders produced by reduction-diffusion process. Alloy powders with only single phase were successfully produced by the reduction-diffusion process. The coercivity of powder rapidly increased during nitrogenation and reached the maximum of 637 Oe after 16 hours. After further nitrogenation, it decreased. In contrast, the coercivity of powder gradually increased during nitrogenation for 24 hours. The coercivity of powder was higher than that of powder at the same condition of nitrogenation. It was considered that the Mn addition facilitates the nitrogenation of powder and enhances the coercivity.

Sputter Cu(1-4.5at.%Mg) alloy를 100mTorr이하의 산소압력에서 온도를 증가시키며 열처리하였을 때 표연과 계면에서 형성된 MgO의 확산방지막 특성을 살펴보았다 먼저, Cu(Mg)/SiO2/Si 구조의 샘플을 열처리했을 때 계면에서는 2Mg+SiO2→2MgO+Si의 화학반응에 의해 MgO가 형성되는데 이 MgO충에 의해 Cu가 SiO2로 확산되는 것이 현저하게 감소하였다. TiN/Si 기판 위에서도 Cu(Mg)과 TiN 계면에 MgO가 형성되어 Cu(4.5at.%Mg)의 경우 800˚C까지 Cu와 Si의 확산을 방지할 수 있었다. 표면에 형성된 MgO위에 Si을 증착하여 Si/MgO(150 Å)/Cu(Mg)/SiO2/Si구조로 만든 후 열처리했을 때 150 Å의 MgO는 700˚C까지 Si과 Cu의 확산을 방지할 수 있었다. 표면에 형성된 MgO(150 Å)의 누설전류특성은 break down 5V, 누설전류 10-7A/cm2의 값을 나타냈다. 또한 Si3N4/MgO 이중구조에서는 매우 낮은 누설전류밀도를 나타냈으며 MgO에 의해 Si3N4 증착시 안정적인 계면이 형성됨을 확인하였다.

Co/Ti 이중막을 급속열처리하여 형성한 CoSi2에 As+을 이온주입한 후, 500~1000˚C에서 drive-in 열처리하여 매우얇은 n+ p접합의 다이오드를 제작하고 I-V 특성을 측정하였다. 500˚C에서 280초 drive-in 열처리하였을 때, 50nm정도의 매우 얇은접합이 형성되었고, 누설전류가 매우 낮아 가장 우수한 다이오드 특성을 나타내었다. 특히, Co 단일막을 사용한 다이오드에 비해 누설전류는 2order 이상 낮았으며, 이는 CoSi2Si의 계면이 균일하였기 때문이다.

본 연구에서는 여러 기판에 대한 Cu의 확산정도를 알기 위하여 Ta, Nb, Co/Ta이중층 및 Co/Nb 이중층 위에 기화법으로 증착하고 열처리를 실시하였다. 열처리한 Ta막은 열처리하지 않은 Ta막보다 Cu 확산방지막으로서의 성능이 더 떨어지는데, 이것은 열처리에 의하여 Ta막이 결정화되기 때문이다. Cu/Co/Ta/(001)Si 구조에서의 구리 실리사이드 생성온도는 Cu/Co/Ta(001)Si 구조에서의 그것보다 더 높다. 한편, nb의 Cu에 대한 barrier 특성은 Ta와 비슷한 수준이다. 또한 Cu막 도포 이전에 Pd+HF활성화 전처리나 N2플라즈마 전처리를 실시하면, Cu의 핵생성뿐만 아니라 기판에 대한 Cu막의 접착성도 향상된다.