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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/2822

    Title: 微陽極導引電鍍法製備微析物之局部電場強度分析;Analysis of the local electric-field strength in the fabrication of micro-deposits by intermittent micro anode guided electroplating
    Authors: 楊仁泓;Jen-hung Yang
    Contributors: 機械工程研究所
    Keywords: 有限元素分析;銅微管;銅微柱;微結構;微陽極導引電鍍;局部電化學沈積;Micro copper tube;Micro copper column;Micrometer structure;Micro-anode guided electroplating;Localized electrochemical deposition (LECD);Finite element analysis
    Date: 2009-07-02
    Issue Date: 2009-09-21 11:57:08 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本論文主旨在利用微陽極導引電鍍法(Micro-Anode Guided Electroplating)以間歇移動方式來析鍍微結構物,論文研究重點在(1)微柱底部之局部性,(2)微柱之形貌,以及(3)微柱之縱剖面探討等三個主題。 研究結果如下: (1) 微柱底部之局部性研究: 在間歇式MAGE製程中,採用單步、步進的陽極移動方式來進行微電鍍,析鍍所得結構物,其底部在基材上圍繞成一個圓形面積,藉由此底部環繞面積的直徑,可以用來定義微柱之局部性(Localization)。以間歇式MAGE單步製程析鍍所得之山丘狀微結構物,其底部圍繞面積之直徑(局部性)隨施加偏壓、兩極間之間距的增加而增加。若以間歇式MAGE步進製程電鍍微柱,其底部直徑會隨著微柱的成長而逐漸增加至一臨界值,微柱超過此臨界高度值後,直徑就不會再繼續增加,此臨界直徑(臨界局部性)的大小取決於施加偏壓以及兩極間的間距。本論文利用有限元素法來分析微電鍍之電場分佈,並建構模型來說明其結果。 (2) 微柱之形貌研究: 以間歇式MAGE製備銅微柱,析鍍物之外觀形貌與內部結構隨著製程參數的改變而有所不同。若析鍍偏壓在4.0V,兩極間距在2μm/step下進行微電鍍,則析鍍出中空管狀結構。若析鍍偏壓從4.0降至3.2V,兩極間距由2增加至25μm/step,則析鍍出一表面光滑組織緻密之實心微柱。在不同製程參數下進行微電鍍,將析鍍出之結構物以有限元素法進行分析,並建立模型定義出一(Ee/Et)電場比例,當此比值大於1.5,析鍍出管狀結構,若此比值小於1.0,則析鍍出實心之柱狀結構。 (3) 沈積微柱之縱剖面研究結果: 微柱之縱剖面可以顯示內部結構。以間歇式MAGE製程製備微柱時,若兩極間固定間距在2μm/step,偏壓施加在3.2~3.6V,會製備出表面粗糙,內部呈孔洞狀鬆散結構。若施加偏壓介於3.6~3.8V時,則析鍍出管壁細緻之管狀結構。當偏壓大於4.0V,則析鍍表面粗糙之管狀結構。 Micrometer metallic pillars were fabricated by the intermittent micro-anode guided electroplating (MAGE) process in order to study (1) the localization of the pillar bottom, (2) the surface morphology of the pillars and (3) the cross-sectional structure along the axis of the micro pillars. The results and contributions of these studies were summarized as follows. (1). Two modes (i.e., one-step and multi-step) of the MAGE process were employed to explore the localization of localized electrochemical deposition (LECD). Circular area around the pillar bottom on the substrate was measured and its diameter was estimated to define the localization of the micro pillars. A tiny hillock was fabricated in one-step MAGE process. The diameter (i.e., localization) of the circle around the pillar bottom increases with increasing the electric biases between the micro anode and the substrate. In the multi-step MAGE process, the diameter of the circle increases with increasing the pillar height and levels off at a critical localization (Dc). The magnitude of the critical localization was found to be a function of electric bias and the initial gap between the micro anode and the pillar top deposited previously. The less the electric bias and the initial gap in multi-step MAGE, the diameter of the circular area around the pillar bottom is smaller. A model of micro-electroplating is proposed based on an electric strength ratio (i.e., Ecore/Ep) between the conical core strength (Ecore) to the conical periphery strength (Ep) and the electric voltage responsible for the critical localization. The strength ratio can be used as a criterion to predict whether a localization diameter increases or not. (2). Micrometer copper features fabricated by intermittent MAGE revealed different structures depending upon the experimental conditions. A hollow micro tube was developed at 4.0 V with an initial distance of 2μm/step. With decreasing the voltage from 4.0 to 3.2 V but increasing the initial distance from 2 to 25μm/step, a dense copper column with a smooth surface was formed instead of a rough-surfaced tube. The dense column was based on a substrate where revealed a larger area of circle around the column compared to that for the hollow tube. Finite element analysis is useful to establish a model for illustrating different morphologies of the micro features attained from MAGE process. According to this model, the structure is determined by the ratio (i.e., Ee/Et) of field strength at the periphery (Ee) to that in the center (Et) of the location. Hollow tubes were fabricated at a ratio higher than 1.5; dense pillars were attained at a ratio less than 1.0. (3). The internal structure of the micro feature was illustrated by examining the cross-sectional morphology along its axis. Fixing an initial inter-electrode distance of 2μm/step, the intermittent-MAGE conducted at 3.2 to 3.6V led to a micro structure with rough surface and porous internal. With increasing the voltage from 3.6 to 3.8V, a micro tube with rough surface was fabricated. Up to 4.0V, an imperfect micro tube with highly rough surface was formed. The mechanism of LECD under different conditions is illustrated by a sequence of models proposed.
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