슈퍼소닉 마이크로 노즐이 장착된 나노 입자 적층 시스템을 이용한 니켈 분말 코팅

Abstract

In this study, supersonic silicon micronozzles were fabricated using Deep Reactive Ion Etching (Deep RIE). Computational Fluid Dynamics (CFD) simulation was performed to determine whether suitable behavior of supersonic fluid can be produced or not. And then Ni powders were deposited using supersonic micronozzle integrated with Nano-Particle Deposition System (NPDS) to form Ni pattern in micro scale. The effect of parameters such as powder size, substrate and Stand-off Distance (SoD), which is the distance between the substrate and the end of nozzle, on deposition behavior was determined. In order to investigate the powder size effect on supersonic deposition, 3 um and 20 nm-sized powers were used and two types of substrates, Si and Su-8, were used to check its effect whether Ni powders can be deposited on organic substrate or not. SoD was varied from 300um to 1000um to determine its effect on deposition properties. Finally, electrical resistance of fabricated Ni line was measured to be used in metal connection. The simulation shows that maximum velocity for fluid can be reached to be greater than 600 m/sec using the fabricated micronozzles. Furthermore, Ni lines were successfully formed on Si and Su-8 substrates using NPDS where supersonic Micronozzle is applied. The thickness of deposited layer on Si substrate using 3um-sized powders was measured to be 5.4 um, with its width being 176.4um at SoD being 300um. In contrast, the deposited average thickness at SoD of 500um was 1.1 um while its width being 190.6um. Therefore, it was found that the deposited thickness decreases as SOD increases, having an inversely proportional relationship. Moreover, the deposited thickness was measured to be 11.9um at SoD of 300um when 20nm-sized Ni powders were used. For deposition behavior depending on the size of powders, it was found that 20 nm-sized Ni powders were deposited thicker than 3 um-sized Ni powders since momentum transfer between carrier gas and powders is inversely proportional to the powder size. As a result for electrical resistivity measurement of deposited Ni line, 1.83 X 10-7 Ωm using 20 nm-sized powders and 1.61 X 10-7 Ωm using 3 um-sized powders were obtained. These values are close to the standard resistivity value for bulk Ni which is 6.9 X 10-8 Ωm, making NPDS highly promising for metal line deposition.