Spectroscopic ellipsometry studies of HF treated Si (100) surfaces

Both ex situ and in situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effects of HF cleaning on Si surfaces. The hydrogen‐terminated (H‐terminated) Si surface was modeled as an equivalent dielectric layer, and monitored in real time by SE measurements. The SE analyses indicate that after a 20‐s 9:1 HF dip without rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF‐etched bare Si (100) surface was observed, in an ultrahigh vacuum (UHV) chamber, and analyzed by the in situ SE. Evidence for desorption of the H‐terminated Si surface‐layer, after being heated to ∼550 °C in the UHV chamber, is presented and discussed. This is the first use of an ex situ and in situ real‐time, nondestructive technique capable of showing state of passivation, the rate of reoxidation, and the surface roughness of the H‐terminated Si surfaces.