以超臨界電鍍銅應用於具矽穿孔晶片製作之製程參數探討

Discussion of Supercritical CO2 Copper Electroplating Parameters for Applications in TSV Chip

賴威宏(Wei-Hong Lai)

指導教授 ： 莊賀喬

共同指導教授 ： 李春穎(Chun-Ying Lee)

國立臺北科技大學/機電學院/機電整合研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00481

摘要

本研究將矽晶圓穿孔 (Through Silicon Via，TSV) 利用超臨界電鍍製程充填銅金屬並製作出具TSV結構之晶片，有別於一般導線只能在2D平面上做佈線，3D結構優勢在於可增加晶片上導線的分佈範圍，由平面增加為多層，因此具有降低成本，減少封裝空間、體積和重量等優點。本研究將晶圓切割成晶片，並使用ICP (感應耦合電漿離子蝕刻)的蝕刻製程技術在晶片上蝕刻TSV，研究超臨界二氧化碳壓力與電流密度之製程參數，探討改變製程參數如何影響電鍍充填TSV銅柱與電阻值，檢測結果將超臨界與傳統電鍍做比較討論。檢測方面則探討TSV銅柱的密封性，使用氦氣測漏儀檢測TSV銅柱是否填孔性良好，而本研究探討TSV的電性檢測為主要重點，電性檢測方面則是量測橫跨於TSV兩端之電阻值，接著在TSV的兩端通高電流(10安培)以檢測TSV是否能承載得住而沒有燒斷，最後將晶片切割剖面以觀察超臨界電鍍所充填之TSV銅柱是否有孔洞的缺陷，並比較超臨界與傳統電鍍製程時間的差異，本實驗之超臨界電鍍製程無加入添加劑輔助電鍍填孔，而是利用超臨界的特性達到填滿TSV孔洞為目標，量測結果壓力值在2000 psi、電流密度為3ASD的電鍍參數較佳，電鍍填孔性效果較好、可承受10安培高電流導通、而超臨界電鍍時間最短為3hr。

關鍵字

TSV ； 超臨界電鍍 ； 3D IC

並列摘要

This study uses supercritical electroplating for the filling of Though Silicon Vias (TSV) in chips for applications in 3D IC structures, which differs from wires that can only be connected in a 2D plain; the structure in a 3D IC has the advantage that the range of connections that can be done is increased, because the area can be added by multiple layers, therefore reducing the cost and decreasing packaging space, volume and weight, etc. In this study we cut the silicon wafer into chips, and the TSV holes are etched by method of ICP RIE (Inductively Coupled Plasma Reactive Ion Etching), the pressure and current density fabrication parameters of the supercritical carbon dioxide are studied, and how the change of these parameters affects the filling of the TSV copper pillar and its resistance is discussed; the final supercritical electroplating results are compared to traditional electroplating techniques. The hermeticity of the TSV copper pillar is analyzed by performing a Helium leaking test on the TSV to check if the filling is satisfactory, and the analysis of electric properties is an important point of this study; for this purpose, the resistance at both horizontal ends of the TSV is measured, and next a high current (10 Amperes) is passed in the same manner to determine if the TSV is capable of withstanding a high current without burnout. Finally, the chip is cut at cross-section to observe the filling of the TSV copper pillars under supercritical electroplating to check for voids, and the fabrication time required for supercritical electroplating and traditional electroplating techniques is compared. The supercritical electroplating fabrication method in the present study has no added any surfactant to aid the electroplating/filling of TSV holes, but relies only on the special properties of the supercritical state to reach the desired goal, the final result of the analysis is that the best electroplating parameters for pressure and current density are 2000 psi and 3 ASD, respectively; the electroplating quality is the best observed and can resist a high current of 10 amperes, and the shortest time for the sc-CO2 electroplating is 3 hours.

並列關鍵字

TSV ； Supercritical Electroplating ； 3D IC

參考文獻

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