The Study of Aluminum/Molybdenum/Copper Etching in Acid Solutions
Date Issued
2006
Date
2006
Author(s)
Chen, Han-Bang
DOI
zh-TW
Abstract
The thesis on behavior of aluminum/molybdenum/copper in acidic etching solution was divided into three parts. The study used not only single metal layer but also double metal layers for etching experiments. The first part is etching of Mo/Al metal layers. The second part is etching of Cu/Mo metal layers the third part is etching of Mo metal layer. In the experiments, the etching rate was measured by time measurement of fixed thickness film been etched through. The interface phenomena in the etching process was investigated by open circuit potential measurement. We also analyzed the surface compositions by XPS, and observed the surface morphology by OM and SEM.
The results of Mo/Al etching indicated that adding HCl in etching solution speeded the etching rate when lowering the concentration of H3PO4. The etching uniformity is bad because HCl would pit aluminum surface. There is always overhang on Mo/Al etching, but it disappeared after over etching. This phenomena could be explained by OCP.
From the results of Cu/Mo etching, we could find that the etching rate difference between copper and molybdenum is large. Thus, it is hard to control the etching uniformity. By changing the composition or pH of etchant or adding additives (BTA), we could make the desired etching rate. The taper after etching is not good because of the structure and reaction potential of metals.
After Mo etching in aluminum etchant, the taper angle is almost 90o. Although the etching rate of H2O2 is slow, it could effective lower the taper angle. Concentrated CH3COOH with H3PO4 and HNO3 also could lower the taper angle besides H2O2.
Subjects
鋁
鉬
銅
蝕刻
電化學
Al
Mo
Cu
Etch
Electrochemical
Type
thesis
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