Ultralevel Assembly of Micron-scale Components

现代机械组装技术目前用于制造集成混合电子结构和复合材料。 诸如在这些系统中的精度和速度之间的权衡以及介电表面上静电荷的无意发展的限制将可行的组件尺寸限制为数百微米。 更快的运动会由于振动增加而导致错位。 静电荷导致零件以不受控制的方式从所需位置移动。自组装技术已被用于组装微米或纳米尺度的复合材料，但仅限于紧密堆积的结构。 微电子工业中目前的趋势是增加集成度和减小元件尺寸，以及微米级复合材料的发展需要新的组装技术。 本研究项目旨在开发这种超水平组装的技术。 超水平组装是指将离散的微米和亚微米级组件直接表面贴装在有源基板（如硅芯片）上。 所提出的方法是一种混合组装工艺，利用静电力和电泳力结合光压力来引导或甚至“飞行”部件就位。 这种混合组装工艺也有望用于由非紧密堆积阵列排列的微米级颗粒组成的复合材料的开发。 所提出的利用静电力来辅助组装的方法是基于控制基板和部件上的局部表面电荷密度。 将使用电晕放电装置在部件上存款均匀的表面电荷，并在基板目标区域上沉积相反极性的电荷。组件和带相反电荷的目标区域之间的库仑力将组件吸引到目标。 电晕放电装置利用平面接地上的高电压下的点电极来引起周围气体的局部电离。 电离的气体分子被加速向地面，并沉积在电介质表面上。 电解质溶液中的电泳定位将用于放置直径小于10微米的部件。 由于电位决定离子的特定吸收，部件的表面将在电解质中采用电荷。 基板表面上的小图案电极将用于产生电场并将带电部分吸引到基板表面。拟议工艺的准确性将由高度控制的库仑力和辐射压力决定，而不是由机械放置系统的定位误差和振动决定。这些力的同时使用将允许离散部件的有效组装，并将引入形成微米级新复合材料的令人兴奋的可能性。不控制微观结构的微粒涂层的电泳沉积已在工业上使用多年。该研究项目旨在使用这种技术将微型元件放置在基板表面的特定位置。 除了这些库仑力之外，使用聚焦激光束将允许更精确地控制部件的位置和取向。这种非接触技术的应用提供了对传统机械装配进行巨大改进的潜力。 这项技术可能会对微电子行业产生广泛的影响。

Modern mechanical assembly techniques are currently used to manufacture integrated hybrid electronic structures and composite materials. Limitations such as the trade-off between precision and speed in these systems and the inadvertent development of static charge on dielectric surfaces limit the feasible component size to hundreds of microns. Faster motion results in misplacement due to increased vibration. Static charge causes parts to be moved from the desired location in an uncontrolled manner. Self-assembly techniques have been used to assemble composite materials on the micron or nanometer scale, but are limited to close-packed structures. The current drive in the microelectronics industry toward increased integration and decreasing component size, and the development of micron scale composite materials require new assembly techniques. This research project seeks to develop techniques for such ultralevel assembly. Ultralevel assembly refers to the surface mount of discrete micron and submicron scale components directly on active substrates such as silicon chips. The proposed method is a hybrid assembly process, utilizing electrostatic and electrophoretic forces in conjunction with light pressure to guide, or even "fly" components into position. This sort of hybrid assembly process is also promising for the development of composite materials made up of micron scale particles arranged in non-close-packed arrays. The proposed method for utilizing electrostatic forces to aid in assembly is based on controlling the local surface charge density on the substrate and component. A corona discharge device will be used to deposit a uniform surface charge on the component, and a charge of opposite polarity onto the substrate target area. The Coulombic force between the component and the oppositely charged target area will attract the component to the target. A corona discharge device utilizes a point electrode at high voltage over a planar ground to cause local ionization of the surrounding gas. The ionized gas molecules are accelerated toward the ground, and deposited on a dielectric surface. Electrophoretic positioning in an electrolyte solution will be used to place parts smaller than 10 micrometers in diameter. The surfaces of the components will adopt a charge in an electrolyte due to the specific absorption of potential determining ions. Small patterned electrodes on the substrate surface will be used to create an electric field and attract the charged parts to the substrate surface. The accuracy of the proposed process will be dictated by the highly controlled Coulombic forces and radiation pressure and not by the positioning errors and vibration of the mechanical placement system. The simultaneous use of these forces will allow the efficient assembly of discreet components and will introduce the exciting possibility of forming new composite materials on the micron scale. %%%Electrophoretic deposition of particulate coatings with no control over microstructure has been used industrially for many years. This research project seeks to use this technique to place micro-components in a specific location on a substrate surface. The use of a focused laser beam in addition to these Coulombic forces will allow more accurate control over the position and orientation of the component. The application of such non-contact techniques offers the potential for vast improvements over traditional mechanical assembly. This technique might have broad impacts in the microelectronics industry.***