Plasma atomic layer etching using conventional plasma equipment

The decrease in feature sizes in microelectronics fabrication will soon require plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching (PALE) is forming a layer of passivation that allows the underlying substrate material to be etched with lower activation energy than in the absence of the passivation. The subsequent removal of the passivation with carefully tailored activation energy then removes a single layer of the underlying material. If these goals are met, the process is self-limiting. A challenge of PALE is the high cost of specialized equipment and slow processing speed. In this work, results from a computational investigation of PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having acceptable processing speeds. Results will be discussed using inductively coupled and magnetically enhanced capacitively coupled plasmas in which nonsinusoidal waveforms are used to regulate ion energies to optimize the passivation and etch steps. This strategy may also enable the use of a single gas mixture, as opposed to changing gas mixtures between steps.