銅/鉬酸性蝕刻液之研究

The Study of Copper/Molybdenum Etching in Acidic Solutions

呂仁雄(Jen-Shiung Lu)

指導教授 ： 顏析成

國立臺灣大學/工學院/化學工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.10046

摘要

本實驗主要針對銅、鉬金屬在酸性蝕刻液中的行為作為進行研究，研究目的主要導因於未來TFT-LCD產業中銅導線結構極有可能沿用鋁導線製程中的雙層結構，亦有可能為了改善銅鍍層和玻璃間附著力不佳的情形而使用Mo-Cu-Mo的三明治結構。以製程簡單化的考量便需要能同時均勻移除相互接合的銅鉬金屬蝕刻液，故蝕刻液必須同時處理兩種金屬。本實驗分為兩部分：第一部分為以雙氧水-磷酸系統進行銅鉬單層金屬蝕刻的速率、極化曲線、表面粗糙度分析。第二部分為針對不同的氧化劑在高濃度磷酸溶液當中的不同蝕刻行為進行細部的機制研究，利用開環電位量測、XPS表面化學成分分析、溶液成分分析以及蝕刻環境條件的調整呈現的不同結果推測溶液與表面界面上的腐蝕機制。
第一部份實驗結果發現在雙氧水-磷酸系統中，銅蝕刻速率的快慢和雙氧水濃度與裡酸濃度均呈現正比的關係，添加檸檬酸、甘醇酸、草酸等有機酸均能抑制銅蝕刻。添加醋酸能在不甚影響蝕刻速率的情況下改善銅表面粗糙度，抑制劑BTA則能有效抑制陰極反應而減緩蝕刻速率。鉬金屬的部分則僅與雙氧水濃度改變有關連，實驗中嘗試的某些添加劑均對其蝕刻行為無顯著影響。
第二部分的實驗結果顯示雙氧水和硝酸在高濃度的磷酸系統當中展現了相當不同的蝕刻行為，雙氧水呈現了較單純且均一的現象，硝酸則隨著時間有明顯的階段變化。主要是因為在表面成不同氧化態的化學物質導致後續的機制不同。硝酸系統產生的氧化物具有和磷酸錯合的多電子轉移複雜機制而表現出和雙氧水系統迥異且多階段的現象。

關鍵字

銅 ； 鉬 ； 蝕刻

並列摘要

This thesis on etching behavior of copper/molybdenum in acidic etching solution
has been investigated in two parts. The main target of this study is base on the
structure of copper wire process which capped a thin Molybdenum layer. In order to
improve the adhesive of copper with glass substrate, sometimes the Mo-Cu-Mo
structure will be used. Obviously, finding etching solution that could dissolve copper
and molybdenum properly at the same time would be the final purpose of this study.
First part of study is using H2O2-H3PO4 to be the basic solution. In the experiments,
the etching rate were measured by weight-loss method & time measurement of fixed
thickness film been etched through. The interface phenomena in the etching process
were also investigated by electrochemical polarization technique, and observed the
surface morphology and roughness by SEM and AFM. The second part of this study is
focus on the mechanism of two different oxidants in concentrated H3PO4 base
solution. We approach the real etching mechanism of etchant on surface by OCP
measurement, XPS analysis and solution analysis.
By studying the effect of H2O2-H3PO4 with various additives, it has been found
that adding citric acid, oxalic acid or glycolic acid would decrease copper etching rate.
The results could be due to the adsorption of organic acid or copper complex formed
by reaction of copper ion and organic acid. Adding oxalic acid over 0.25 M would
terminated the etch reactions intermediately. With complex effect, adding inhibitor
BTA decreased etching rate due to its inhibition for cathodic reation. Molybdenum
etching behavior just affect by different concentration of H2O2.
The result of the second part of the study indicated that H2O2 and HNO3 has
shown different phenomena during etching proceed. By results of OCP, XPS and
III
solution analysis, we concluded that different phenomena due to different ratio of
composition on surface. Oxide formed in HNO3 system had shown multi-step change
during etch and had a multi-electron transfer complex mechanism with H3PO4.

並列關鍵字

Copper ； Molybdenum ； etching

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