A study on etching properties of 6061 Al alloy by dual-frequency (60 MHz/400 kHz) capacitively coupled Ar, Ar/O 2 , NF 3 /Ar and NF 3 /Ar/O 2 plasma

Abstract Plasma-induced corrosion limits the lifetime and stability of semiconductor etching equipment. 6061 Al alloy, widely used in etching platforms, is susceptible to corrosion under prolonged plasma exposure. In this study, Al alloy samples were etched using Ar, Ar/O 2 , NF 3 /Ar, and NF 3 /Ar/O 2 plasmas. The results show that the etching rates in Ar and Ar/O 2 plasmas are relatively low, being dominated by physical sputtering and oxidation passivation, respectively. After introducing NF 3 into the Ar plasma, the etching rate of the Al alloy increases by nearly one order of magnitude due to the synergistic effect between fluorination reactions and ion sputtering. In the NF 3 /Ar/O 2 system, with the O 2 flow rate kept constant, an appropriate amount of Ar effectively breaks metallic bonds and accelerates the removal of AlF 3 , resulting in an increased etching rate, whereas excessive Ar leads to a decrease in the etching rate. In addition, etching products preferentially accumulate at grain boundaries and second-phase regions, while sputtering pits are formed within the grains. After etching in a NF 3 plasma, Al alloy on the surface predominantly exists in the form of AlF 3 . This study provides valuable insights into plasma-induced corrosion of Al alloy in semiconductor manufacturing processes.