Hyperthermal neutral beam etching

• Published in: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films Vol. 13; no. 3; pp. 959 - 965
• Main Authors: Giapis, Konstantinos P., Moore, Teresa A., Minton, Timothy K.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: 01-05-1995
• Subjects: PULSED IRRADIATION; ATOMIC BEAMS; ANGULAR DISTRIBUTION; Si; SILICON; CHEMICAL REACTIONS; ETCHING; FLUORINE; AMBIENT TEMPERATURE; ATOM COLLISIONS
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.579658

A pulsed beam of hyperthermal fluorine atoms with an average translational energy of 4.8 eV has been used to demonstrate anisotropic etching of Si. For 1.4 Hz operation, a room‐temperature etch rate of 300 Å/min for Si(100) has been measured at a distance of 30 cm from the source. A 14% undercutting for room‐temperature etching of Novolac‐masked Si features was achieved under single‐collision conditions, with no detectable mask erosion. Translational energy and angular distributions of scattered fluorine atoms during steady‐state etching of Si by a normal‐incidence, collimated beam demonstrate that unreacted F atoms can scatter inelastically, retaining a significant fraction of their initial kinetic energies. The observed undercutting can be explained by secondary impingement of these high‐energy F atoms, which are more reactive upon interaction with the sidewalls than would be expected if they desorbed from the surface at thermal energies after full accommodation. Time‐of‐flight distributions of volatile reaction products were also collected, and they show evidence for a dominant nonthermal reaction mechanism of the incident atoms with the surface in addition to a thermal reaction channel.