添加劑對鈷基薄膜上以電化學原子層沉積銅薄膜之研究

Additives Affecting the Growth of Cu Thin Film Prepared on Cobalt-Based Substrates by Electrochemical Atomic Layer Deposition

林隆奕(Long-Yi Lin)

指導教授 ： 方昭訓

國立虎尾科技大學/工程學院/材料科學與工程系材料科學與綠色能源工程碩士班/碩士(2016年)

摘要

本研究第一部份探討添加劑對於電化學原子層沉積(EC-ALD)在濺鍍鈷薄膜的二氧化矽基板上沉積銅薄膜之影響。首先以欠電位沉積一層鉛原子層做為犧牲層，再藉由加入不同添加劑之銅溶液與犧牲層原子進行表面侷限氧化還原反應置換出銅原子層，並且比較不同添加劑對於置換銅薄膜的影響。實驗結果藉由四點探針分析電性、X光繞射儀進行相結構分析、掃描式電子顯微鏡及原子力顯微鏡分析薄膜表面形貌，以及電化學分析儀分析添加劑對鈷薄膜腐蝕影響。
結果顯示添加檸檬酸鈉製備出的銅薄膜含鉛量過高，源自於檸檬酸鈉降低了銅的置換效率使得犧牲層鉛原子殘留。而添加過氯酸鈉製備出的銅薄膜結晶性與電性良好，卻由於溶液中Cu2+離子含量過高對鈷薄膜有伽凡尼腐蝕影響，造成沉積的銅薄膜附著性不佳容易剝落。在添加乙二胺製備出的銅薄膜置換效率佳，且能降低Cu2+對鈷薄膜之腐蝕影響薄膜穩定性最佳。
第二部分則是以添加乙二胺之銅溶液藉由EC-ALD在無電鍍CoP、CoWP基板上沉積銅薄膜並探討薄膜熱穩定性。結果顯示添加乙二胺之銅溶液能成功以EC-ALD在無電鍍鈷合金基板上沉積銅薄膜，經快速退火熱處理CoP基板上之銅薄膜熱穩定性可至550oC，CoWP基板上之銅薄膜熱穩定性至500 oC。

關鍵字

電化學原子層沉積 ； 銅金屬化製程 ； 鈷基板 ； 乙二胺

並列摘要

The effect of the additives on electrochemical-atomic-layer-deposited copper film on Co/SiO2/Si substrate was investigated. An underpotentially -deposited (UPD) Pb atomic layer was used as a sacrificial layer. The following Cu film was prepared using surface limiting redox reaction in copper solution with different additives. Additives significantly affect the replacement of UPD – Pb by Cu. The resistance of the film was measured by four points probe. Crystal structure was analyzed by x-ray diffraction. The surface morphology was analyzed by scanning electron microscope and atomic force microscope. Corrosive effect of the additives on cobalt film was analyzed by electrochemical analyzer.
The results showed that lead residual exist in Cu film when adding sodium citrate because sodium citrate reduces the efficiency of copper displacement. On the other hand, sodium perchlorate increases crystallinity and electrical properties of the Cu film. However, the high content of Cu2+ ions in solution enhances the galvanic corrosive on the cobalt film, resulting in the poor adhesion of copper film. Ethylenediamine increases the replacement efficiency of copper film and reduces the corrosion of cobalt film. Thus, the Cu film can be stabilized.
In the second part of the study, we investigated the thermal stability of the added ethylenediamine in copper solution to prepare copper film on CoP and CoWP substrates using EC-ALD. The results showed that the copper film can be successfully deposited on the electroless cobalt-based substrate by EC-ALD. The Cu on CoP substrate is thermally stable up to 550oC, and Cu on CoWP substrate is thermally stable at 500oC.

並列關鍵字

Electrochemical atomic layer deposition (EC-ALD) ； copper metallization ； cobalt substrate ； ethylenediamine

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