IN-SITU DC-PLASMA CLEANING OF SILICON SURFACES

The native oxide and carbon contamination on silicon wafers are removed in situ by a direct current H/Ar-plasma cleaning process. The residual contamination after the surface cleaning lies under the detection limit of secondary ion mass spectroscopy (SIMS). However, scanning tunneling microscope (STM) measurements show a surface roughness with a peak-to-peak amplitude of 4 nm on a lateral scale of 20 nm. Photoemission results (UPS) reveal the dangling bonds to be saturated with hydrogen. Upon annealing, reflection high energy electron diffraction (RHEED) and thermal desorption spectroscopy (TDS) show that the surfaces flatten after the final hydrogen desorption step at temperatures of 450-500 degrees C.