硫尿對化學銅析鍍之影響

Effects of Thiourea on Electroless Copper Deposition

曾宏逸(Hung-Yi Tseng)

指導教授 ： 張俊賢

國立臺北科技大學/工程學院/化學工程所/碩士(2006年)

摘要

銅製程之出現乃因半導體晶片上原有之鋁導線材料面臨瓶頸，當製程技術縮小至0.25微米甚至更小，導線寬度也隨之變窄，鋁之高阻值（r =2.8mW-cm）特性使得訊號傳輸時間愈來愈長，在IC產品對速度要求極高之特性下，導電性極佳之銅（r =1.7mW-cm）將成為下一代導線技術之主要材料。
本實驗室發展一化學銅配方於鍍浴中加入硼酸緩衝溶液但銅鍍層粗糙、電阻率高。為改善鍍層性質本論文加入添加劑Thiourea 於鍍浴中，探討Thiourea 對化學鍍銅鍍層之析鍍速率、表面形態、晶粒大小及電阻率，結果發現鍍液中含微量 Thiourea 析鍍速率變快 、電阻下降、表面較平整、結構較緻密…等。亦利用電化學阻抗光譜（Electrochemical Impedance Spectroscopy,EIS）來研討添加劑Thiourea 影響化學鍍銅析鍍之機制，並模擬求出以銅為工作電極之電化學電解之等效電子電路圖。研究發現在含有添加劑Thiourea 之化學鍍銅析鍍液中，以銅為工作電極之電雙層電荷轉移阻抗值（Rct）與電容值（Cdl）都增加。

關鍵字

交流阻抗光譜 ； 化學銅析鍍速率 ； 銅鍍層組成分

並列摘要

The emergence of copper manufacturing process has come about because of the existent bottleneck of the aluminum material used for the conducting wires on semiconductor chips. As the manufacturing processes reduce the component size in ICs to less than 0.25 mm, the width of conducting wires reduces accordingly. The high resistivity of aluminum prolongs the time needed for signal transmission. To meet the strict demand for IC products, copper with superior electric conductivity will surely be a very important material used for conducting techniques.
The main purpose of this research is to investigate the effects of Thiourea on the plating rate, surface morphology, chemical composition and resistivity of copper deposition. And to study mechanism of Thiourea on electroless copper deposition by the electrochemical impedancespectroscopy, the double layer capacitance and resistance of the working electrodewere calculated. The equivalent electronic circuit for the electrochemical cell of electroless copper deposition will be obtained by simulation to further understand the effect of additive on electroless copper deposition.
The results show that with addition of Thiourea as additive the borate buffered electroless copper plating solutions was stabilized and the platingrate was decreased with addition Thiourea, surface morphology of copper deposition was smoothed, the texture coefficient remained the same within experimental error, the size of the crystal was decreased, the oxygen content of copper deposition was decreased, the resistivity was decreased with addition Thiourea in plating solution.The charge transfer resistance and double layer capacitance of the working electrode were increased.

並列關鍵字

electrochemical impedance spectroscopy ； electroless copper plating,chemical composition ； resistivity ； surface morphology

參考文獻

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