On the Use of H2 Plasma for the Cleaning and Passivation of InP Substrates

The effectiveness of hydrogen plasma for the reduction process of surface native oxide on InP substrates is investigated by X-ray photoelectron spectroscopy (X'S) and by phase modulated spectroscopic ellipsometry PMSE). H2 plasmas, generated in a quartz tube by ap lying a r.f. field (13.56 MHz) to external electrodes, produce a very high H-atom flux (5.10~0 atoms/cm. g ec) in the doregion. The ex-situ XPS and in-situ PMSE measurements indicate fhat the native oxide layer (25 A) is completely removed. The end point of the cleaning process is well detected by kinetic ellipsometry. The plasma treated surface shows a higher stability to reoxidation than that observed for wet etches samples.