Method of plasma-enhanced atomic layer etching

A method for etching a layer on a substrate placed between electrodes in a reaction space by an atomic layer etching (ALE) process which comprises at least one etching cycle, wherein an etching cycle comprises:

• continuously providing an inert gas flowing at least as a carrier gas for an etching gas into the reaction space, wherein the carrier gas flows through a mass flow controller and then through a gas manifold disposed upstream of the reaction space, said inert gas referring to a gas that does not etch the substrate in an unexcited state;
• providing a pulse of an etching gas into the continuous inert gas flow upstream of the reaction space to chemisorb the etching gas in an unexcited state on a surface of the substrate in the reaction space, wherein the etching gas flows through a mass flow controller and is converged into the carrier gas flow downstream of the mass flow controller for the carrier gas and upstream of the gas manifold;
• continuously providing a reactant gas other than the carrier gas and the etching gas into the reaction space, wherein each reaction gas flows through a mass flow controller and is then converged into the etching gas with the carrier gas at the gas manifold;
• and
• providing a pulse of RF power discharge between the electrodes to generate a reactive species of the inert gas in the reaction space and to contact the etching gas-chemisorbed surface of the substrate with the reactive species so that the layer on the substrate is etched.