Plasma-Surface Interaction Limits for Remote H-Plasma Cleaning of Si(100)

Abstract

An investigation of the parameters in H-plasma cleaning influencing H-diffusion and surface etching is described. The Si surface and subsurface regions were characterized with Raman spectroscopy and high resolution transmission electron microscopy (HRTEM), and the plasma parameters were monitored with a double Langmuir probe and optical emission spectroscopy. The parameters varied in the rf plasma cleaning were the substrate temperature, the rf power, and the plasma exposure time. It was found that low pressure and low power H-plasma exposure was effective in terms of cleaning the surface. In the 300°C, 20 Watts, 2 min. H-plasma exposure case, the Raman spectra indicated that there was no detectable H incorporation into the Si bulk and HRTEM showed no obvious defect microstructure in the near surface region and that the surface was smooth. In contrast, in the 150°C, 50 Watts, 60 min. H-plasma exposure case, HRTEM indicated that H-induced platelet defects formed in the Si(100) subsurface region and that the surface morphology was rough. Raman scattering revealed Si-H features at ~2100 cm^-1.