Hyperthermal neutral beam etching

Abstract

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 Si͑100͒ 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.

Gas-Surface Dynamics and Profile Evolution during Etching of Silicon

“…Scattering dynamics are difficult to study in complex plasma environments, although a controlled study with an energetic beam of reactive atoms can reveal fundamental interaction dynamics that may govern etch topography evolution. Such experiments are directly related to plasma etching because (1) most ions undergo Auger neutralization before hitting the surface and scatter as neutral atoms, (2) fast neutrals, produced by charge exchange collisions, may exist in high density plasmas, and (3) profiles etched with molecular beams [10] exhibit characteristics analogous to those etched in plasmas. We report here on the scattering dynamics of energetic F-atom beams on SiF x during steady-state etching.…”

“…The bimodal TOF distributions of the dominant reactive product, detected as SiF 3 1 , suggest at least two interaction mechanisms, one thermal and the other nonthermal, that lead to the ejection of volatile reaction products [10]. The nonthermal reaction probability S is modeled by…”

“…The experimental methods were described earlier [10]. A broad pulse of energetic F atoms, produced by laser detonation of SF 6 , was chopped to narrow the beam velocity distribution.…”

Generation of energetic He atom beams by a pulsed positive corona discharge

“…For example, the corona source may prove to be simpler, more compact, and more versatile than the laserdetonation sources currently being developed for applications in semiconductor etching. 24 …”

Highly Selective and Low Damage Etching of GaAs/AlGaAs Heterostructure using Cl2/O2 Neutral Beam

“…Many studies have been conducted previously and are currently being conducted to generate parallel and low energy neutral beams and to etch materials vertically without having electrical charging and physical damage [8][9][10][11][12]. In this study, to etch the GaAs on AlGaAs selectively and vertically with low damage and with low contamination, a low energy Cl 2 /O 2 neutral beam was introduced.…”