The Study of Copper/Molybdenum Etching in Acidic Solutions
Date Issued
2005
Date
2005
Author(s)
Lu, Jen-Shiung
DOI
zh-TW
Abstract
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.
Subjects
銅
鉬
蝕刻
Copper
Molybdenum
etching
Type
thesis
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