Wet Cleaning/Etching of NiAl Thin Film

Abstract

The effect of various chemical solutions and mixtures on the etch characteristics, roughness change, and surface composition of NiAl, Al, and Ni films were investigated. Both HCl solution (1.82%) and NH4OH (0.6 and 1.45%) solutions were found to have a detrimental effect on NiAl film in terms of material etching (4-point probe results) and surface roughness change (AFM). Within the concentration range applied, adding H2O2 into the HCl or NH4OH solutions resulted in a significant increase of the etching of the NiAl film. A correlation was observed between the magnitude of etching and increase in surface roughness suggesting that a preferential etching occurred, most likely of grain boundary. Experimental results showed that in the case of 1.82% HCl-H2O2 mixture, NiAl surface can be protected up to 240 s of immersion with the use of a corrosion inhibitor such as triazole (TA).