Atomic layer etching of SiO2 with Ar and CHF3 plasmas: A self‐limiting process for aspect ratio independent etching

• Published in: Plasma processes and polymers Vol. 16; no. 9
• Main Authors: Dallorto, Stefano, Goodyear, Andy, Cooke, Mike, Szornel, Julia E, Ward, Craig, Kastl, Christoph, Schwartzberg, Adam, Rangelow, Ivo W, Cabrini, Stefano
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-09-2019
• Subjects: Argon; Argon plasma; Aspect ratio; Constraining; Electrodes; Etching; Fluorine; Inductively coupled plasma; Plasma etching; Silicon dioxide; Silicon oxides; Substrates; Surface layers
• ISSN: 1612-8850; 1612-8869
• DOI: 10.1002/ppap.201900051

With ever increasing demands on device patterning to achieve smaller critical dimensions, the need for precise, controllable atomic layer etching (ALE) is steadily increasing. In this work, a cyclical fluorocarbon/argon plasma is successfully used for patterning silicon oxide by ALE in a conventional inductively coupled plasma tool. The impact of plasma parameters and substrate electrode temperature on the etch performance is established. We achieve the self‐limiting behavior of the etch process by modulating the substrate temperature. We find that at an electrode temperature of −10°C, etching stops after complete removal of the modified surface layer as the residual fluorine from the reactor chamber is minimized. Lastly, we demonstrate the ability to achieve independent etching, which establishes the potential of the developed cyclic ALE process for small scale device patterning.