Cryo Plasma Etching of Porous Low-k Dielectrics

Non-destructive plasma etching processes for dielectrics with ultra-low dielectric constant are relevant for forming metallization systems of integrated circuits with a design rule of less than 28 nm. The paper demonstrates the process of atomic layer etching of dielectrics with ultralow permittivity. The process is based on the adsorption of C4F8 gas in the pores of the film in the first stage of the cycle at cryogenic temperatures (up to - 120 degrees C) and activation of the reaction by bombardment with accelerated particles in the second stage. The proposed process is promising because the gas condensed on the surface of the pores protects their walls from chemical degradation.