Electrochemical Behavior of Copper in Post-Via-Etch Cleaning Solutions
Résumé
The actions of glycolic acid and BTA on copper have been investigated by electrochemical methods. Different concentrations in glycolic acid were investigated: 1%wt, 2%wt, 3%wt and 4%wt. Results show that the cleaning action of glycolic acid results from smooth corrosion of the metal. Copper dissolution increases with glycolic acid concentration due to the formation of a copper complex which precedes copper dissolution. In the presence of BTA, a corrosion inhibitor of copper, a [Cu(I)BTA] complex is formed on the surface which blocks copper dissolution. In a mixture of glycolic acid and BTA (1%wt/ 0.1%wt), an intermediary behavior is observed. A competitive action occurs between the film formation due to the interaction between BTA and copper and the superficial etching of the metal by glycolic acid which removes the inhibitor-copper film.