Silicon surface cleaning by low dose argon-ion bombardment for low-temperature (750 °C) epitaxial silicon deposition. I. Process considerations

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Abstract
A low‐energy argon sputter process has been optimized to successfully remove native oxide from a silicon surface at elevated temperatures without introducing permanent damage. The process relies upon confining all sputtering events to the near‐surface region of the silicon and exploits the enhancement of sputter efficiencies observed for silicon and silicon dioxide above 600 °C. The procedure has been implemented as an in situ etch for low‐temperature (below 800 °C), very low‐pressure (1–10 mTorr), epitaxial silicon deposition in a high vacuum ambient. The reactor and conditions employed are presented along with measures of residual substrate damage as a function of processing conditions, and the process limitations are discussed. A companion paper describes the excellent structural quality of the resultant epitaxial films. The ion energies (100 eV) and fluxes (5×1013 cm−2 s−1) employed represent a significant departure from conventional sputter cleaning processes.