Etching of undoped Si1-xGex epitaxial films (v = 0-1) has been investigated using an electron-cyclotron-resonance chlorine plasma. It is found that the etch rate of Si1-xGex increases with increasing Ge fraction and decreases with increasing Cl2 pressure. From the comparison of the etch rate with the number of the incident ions toward the wafer and the relative radical density in the plasma, it is also found that the etching of Si1-xGex with low x is induced mainly by chlorine ions, and for high x, the contribution of radicals to the etching becomes larger. From the angular resolved x-ray photoelectron spectroscopy analysis, it is found that the etching by chlorine radicals causes surface segregation of Si with the concentration of about 1-1.5×1014cm-2 on the etched Si1-xGex surface.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)