Simulation of anisotropic etching of silicon in SF6 + O2 plasma

The two-dimensional reactive ion etching of silicon in SF6 + O2 plasma is considered. The profiles of etched trenches are calculated as a function of mask dimensions, concentrations of chemically active plasma components and ion bombardment parameters. The theoretically calculated profiles of etched trenches are compared with experimentally measured. The physical and chemical mechanisms underlying the processing are examined using numerical simulations. It is found that the decrease in temperature increases the etching anisotropy due to the decreased desorption of formed SiF4 molecules from the sidewalls.