Unraveling the surface behavior of amino acids on Cu wiring in chemical mechanical polishing of barrier layers: A combination of experiments and ReaxFF MD

Amino acids, as basic chemical additives, promote the development of novel chemical mechanical polishing (CMP) slurries and have been widely applied in microelectronic industries because of their high efficiency, nonpolluting nature and low cost. In this work, the surface action mechanisms of glycine, sarcosine, and L-glutamic acid on copper were studied by combining electrochemical measurements, morphological characterization, and ReaxFF MD simulations. The results show that these three amino acids can complex copper ions effectively and generate complexes, which can form a composite film with amino acid molecules and copper oxides to adsorb on the Cu surface to prevent the local attack of a corrosion medium on the copper. In particular, the processed slurry containing sarcosine has the best balance between the complexation ability and the corrosion inhibition effect, by which a better surface morphology of Cu can be obtained while complexing with Cu ions effectively. Additionally, ReaxFF MD simulations provide atomic insight into the removal of Cu atoms under the synergetic action of chemical and mechanical effects. The removal of Cu atoms by amino acids mainly occurs through the synergetic effects of Cu-N binding and mass transfer, while the corrosion inhibition efficiency mainly comes from the strong adsorption ability caused by the binding and intercalation of Cu-O bonds on the Cu substrate. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study on the surface action mechanisms of amino acids on copper shows that they can effectively complex copper ions and generate composite films to prevent local corrosion on copper surface. Slurries containing sarcosine exhibit the best balance between complexation ability and corrosion inhibition effect, leading to improved surface morphology of copper.