Effects of Sodium Thiosulfate on Electroless Copper Deposition

• Main Authors: Kuang-Yang Lee, 李光耀
• Other Authors: Jun-Shang Chang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/48171959008309379791

碩士 === 國立臺北科技大學 === 化學工程系碩士班 === 92 === Recently copper has been used to replace Al metallization in ultra large scale integrated (ULSI) technology because of low resistivity and stress-induced voiding. Copper can be deposited by physical vapor deposition, thermal-induced reflow, chemical vapor deposition, electroplation and electroless deposition. Electroless copper deposition can be processed with high speed in mass production. Therefore, Electroless copper deposition would be a potential technology for the manufacture of ULSI. The main purpose of this research is to investigate the effects of sodium thiosulfate on the plating rate, surface morphology, crystal structure, chemical composition and resistivity of copper deposition. And to study mechanism of sodium thiosulfate on electroless copper deposition by the electrochemical impedance spectroscopy, the double layer capacitance and resistance of the working electrode were 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 sodium thiosulfate as additive the borate buffered electroless copper plating solutions was stabilized and the plating rate was decreased from 14.68 μm/hr to 4.18 μm/hr with addition of 20 mg/l sodium thiosulfate, 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 from 51.49 μΩ-cm to 2.36 μΩ-cm with addition of 20 mg/l sodium thiosulfate in plating solution.The charge transfer resistance and double layer capacitance of the working electrode were increased.