The Study of Formation and Collective Behaviors of Fine Silicon -oxide Particles in RF Weakly Ionized Plasmas

• Main Authors: Jen-Hung Chu, 朱仁弘
• Other Authors: Lin I
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/34094478998016282107

博士 === 國立中央大學 === 物理與天文學研究所 === 82 === Fine SiO2 paricles are fabricated through gas phase homogeneous chemical reactions and nucleations in rf magnetron discharge in SiH4/O2/Ar gas mixtures. For P>30 mTorr, primary fine particles (PFPs) with diameter about 20 nm can be formed and their diameter increases with the system pressure. They can aggregate with other PFPs to form larger aggregated fine particles (AFPs) with nearly spherical shape. The size of the AFP depends on the duration of the rf power. The homogeneous process creates oxide particles with more relaxed Si-O bonding than the surface- process-dominated counterpart. The plasma-generated fine particles are negatively charged and suspended in the plasma. The accumulation of fine particles causes low-frequency (about 10 Hz) spatiotemporal oscillation of the discharge. At high pressure (>200 mTorr), the random fluctuations of the discharge and the particle motions are suppressed. The Coulomb solids and liquids are directly observed for the first time using an optical microscope in the rf weakly ionized plasma. By properly controlling the system parameters, 3-d hexagonal, face-centered cubic (fcc), body-centered cubic (bcc) and hexagonal close- packed (hcp) crystal structures and solids with coexisting different crystal structures can be obtained. The defects and the growth of the 3-d hexagonal crystal are also observed. Increasing the rf power causes the transtion to the more disorder liquid state and it exhibits a first-order phase transition.