在醋酸-雙氧水系統中銅之蝕刻研究

The Study of Copper Etching in Acetic Acid-Hydrogen Peroxide Solutions

鄭博元(Po-Yuan Cheng)

指導教授 ： 顏溪成

國立臺灣大學/工學院/化學工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802225

摘要

在顯示面板領域，銅製程因導電性佳、傳導速度快等優點逐漸取代鋁製程，銅製程在高精細度的要求下，蝕刻速率需不能過快且穩定。本實驗利用重量損失法量測各種蝕刻液中的銅蝕刻速率，利用直流極化測試法探討蝕刻過程中，銅表面可能發生的現象及反應。最後藉由能量色散X-射線光譜分析蝕刻後表面元素組成，利用掃描式電子顯微鏡觀察表面形貌，並使用原子力顯微鏡量測表面粗糙度。
實驗結果發現在醋酸-雙氧水系統中，銅蝕刻速率的快慢和雙氧水濃度與醋酸濃度的關係，在一定濃度內呈正相關，兩者的過度添加則會降低蝕刻速率。添加甘胺酸(glycine)與醋酸銨(ammonium acetate)，因螯合作用，蝕刻速率則呈現先下降後上升的趨勢。添加腐蝕抑制劑苯並三唑(benzotriazole)、苯並咪唑(benzimidazole)則能有效抑制陰極與陽極反應而減緩蝕刻速率。添加檸檬酸(citric acid)、酒石酸(tartaric acid)、甘醇酸(glycolic acid)等羧酸類，因本身的吸附或與銅錯合物的吸附皆會使蝕刻速率下降。添加聚乙二醇(PEG 600)則會抑制陰極反應使蝕刻速率下降。在醋酸-醋酸銨-雙氧水系統中，添加苯並咪唑也使蝕刻速率下降，添加甘醇酸則呈現先下降後上升的趨勢。另外藉由阿瑞尼斯方程式求出蝕刻反應的活化能，發現無論添加何種添加劑，活化能皆介於70~80 kJ/mol，為表面反應控制。另外在蝕刻液壽命測試，利用開環電位量測及氧化還原滴定，得知氨與銅離子會生成銅氨錯離子而催化雙氧水分解，造成蝕刻液性能衰退。

關鍵字

銅 ； 蝕刻 ； 醋酸 ； 雙氧水

並列摘要

Since wet copper metallization processes require the fineness of the copper lines, the appropriate and stable copper etching rates are needed. In this study of copper etching in acetic acid-hydrogen peroxide systems, the copper etching rates were measured by the weigt loss method and the interfacial phenomena in the etching process were also investigated by electrochemical polarization technique. The surface compositions and morphology were analyzed by EDX and SEM, respectively. The surface roughness was also measured by AFM. The results in acetic acid -H2O¬2 system showed that the etching rate was positively correlated to the concentrations of acetic acid or hydrogen peroxide in the certain range of concentrations. However, Over-dosing of acetic acid or H2O2 was not beneficial for increasing etching rate. When ammonium acetate or glycine was added, the etching rate decreased first and then increase later because of the chelation. Adding inhibitor benzotriazole or benzimidazole would decrease etching rate because of inhibition for both anodic and cathodic reactions. Benzimidazole showed better performance over benzotriazole. Adding citric acid, tartaric acid and glycolic acid would decrease etching rate because of the adsorption of carboxylic acid or complex formed by reaction of copper ion and carboxylic acid.
For the investigation of acetic acid-ammonium acetate-H2O¬2 system, adding benzimidazole decreased etching rate. Adding glycolic acid resulted that the etching rate first decreased, and then increased. Arrhenius plots showed that the etching process were reaction controlled and the activation energies were between 70 and 80 kJ/mol, if the H2O2 concentration is high enough. In the test of etchant H2O2, the results of OCP measurements and redox titrations indicated that copper ammonia complex could catalyze the decomposition of hydrogen peroxide, leading to decay of the etchants.

並列關鍵字

Copper ； Etching ； Acetic acid ； Hydrogen peroxide

參考文獻

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