Deposition of Ultra Fine Aerosol Particles on Solid Surfaces

半导体制造过程中亚微米颗粒的沉积是导致产量下降的主要原因之一。为了抑制颗粒在各种材料表面的沉积，必须充分了解亚微米颗粒的沉积机制。本文首先利用不同材料制成的圆管，实验研究了粒子在不同充电状态下的沉积。所研究的管材料有铜、玻璃、聚甲基丙烯酸甲酯（PMMA）、聚氯乙烯（PVC）、聚碳酸酯（PC）和聚乙烯（PE）。结果发现：1)在所有的实验管中，不带电粒子都是通过布朗扩散沉积的；2) PMMA、PVC、PC和PE管中带电粒子通过库仑力沉积，且无因次沉积速度等于推导出的带电粒子和带电无限平面的库仑力参数。此外，从粒子的时间依赖性的测量中发现，PVC和PC管上的摩擦电荷的衰减服从双曲线衰减规律。其次，利用荧光法建立了测量直径小于0.3 m的颗粒在晶圆上沉积速度的实验技术。利用该技术，在0.02 ~ 0.5m/s的风速下，测量了电荷平衡粒子和直径为0.03 ~ 0.8 m的单电荷粒子在晶圆上的沉积速度。测量的沉积速度与Liu和Ahn的方程预测的速度进行了比较。结果表明，Lie和Ahn的方程可以很好地预测粒径在0.03 ~ 0.8 m之间的粒子，并且当晶圆和粒子都带电时，通过在方程中加入库仑漂移速度，可以很好地估计沉积速度。此外，通过测量与气流垂直放置的晶圆上的局部沉积速度，发现沉积热点出现在晶圆的边缘和/或晶圆的中心，这取决于晶圆对气流的阻塞程度。少

Deposition of submicron particles in the manufacturing process of semiconductors is one of the main causes of reducing production yield. In order to suppress particle deposition onto the surface of various materials, the deposition mechanisms of submicron particles have to be well understood. In the present work, first, by using circular tubes made of various materials, deposition of particles in various charging states was experimentally investigated. The tube materials studied were copper, glass, polymethylmetacrylate(PMMA), polyvinylchloride(PVC), pllycarbonate(PC), and polyethylene (PE). As a result it was found that 1) uncharged particle deposits by Brownian diffusion in all the tubes studies; 2) charged particle deposits in PMMA, PVC, PC and PE tubes by coulombic force, and that the dimensionless deposition velocity is equal to the coulombic force parameter derived for charged particle and charged infinite flat surface. Further, from the measurement of time dependency of particle … More penetration, decay of triboelectric charged on PVC and PC tubes was found to obey the law of hyperbolic decay. Secondly, experimental technique to measure deposition velocity onto wafer for particles with a diameter smaller than 0.3 m was developed by means of fluorometry. Employing the proposed technique, the deposition velocity onto the wafer was measured for charge equilibrium particles and singly charged particles with diameter between 0.03 and 0.8 m at airflow velocity of 0.02-0.5m/s. The measured deposition velocity was compared with that predicted by Liu and Ahn's equation. As a result, it was found that the Lie and Ahn's equation gives a good prediction for particles in the size range between 0.03 and 0.8 m, and , when both the wafer and the particles are charged, the deposition velocity is well estimated by adding the coulombic drift velocity to their equation. Further, through the measurement of the local deposition velocity on the wafer placed normal to the airflow, the deposition hot spots were found to appear on the edge of the wafer and/or at the center of the wafer, depending on the blockage of the wafer to the airflow. Less