Low temperature copper etching using an inductively coupled plasma with ultraviolet light irradiation

Abstract

Inductively coupled plasma etching of copper under ultraviolet irradiation is proposed using a Cl-2/N-2 or Cl-2/Ar gas mixture. Ultraviolet light irradiation lowers the activation energy for copper etching from 1.6 to 1.12 eV and enhances CuCl desorption, which makes it possible to etch copper at low temperatures. We achieved an etch rate of about 300 nm/min even at room temperature. The etch rate increases almost linearly with increasing ultraviolet light intensity. It is suggested that the etching process is not a simple thermal process, but a photodesorption of CuCl due to ultraviolet irradiation.