Etching of organosilicate glass low-k dielectric films in halogen plasmas

The chemistry and kinetics of alternative etching chemistries for low-k dielectric materials are explored to improve the anisotropy of the etching process and to reduce the problems associated with postetch clean-up. Etching rates, selectivities, and etching yields of Black Diamond and Coral organosilicate glasses (OSGs) have been measured. Black Diamond and Coral are etched rapidly in F₂, Cl₂, and HBr high density plasmas, and Cl₂+HBr plasmas have been identified as a viable process chemistry with several advantages over traditional fluorocarbon plasmas. The OSG films are not spontaneously etched by F₂, Cl₂, HBr molecules, Cl, or Br atoms, however, F atoms etch the OSGs spontaneously. F, Cl, and H atoms extract a substantial amount of carbon from the films, but Cl and H do not attack the OSG oxide matrix. The Coral films are more strongly depleted of carbon after halogen plasma etching than the Black Diamond. In addition, oxygen atoms extract nearly all of the carbon and nitrogen from the OSGs, leaving a stoichiometric SiO₂ layer. © 2002 American Vacuum Society.