Oxidation of rf plasma: hydrogenated crystalline Si

The growth kinetics of thermal oxidation of H-plasma hydrogenated (100) and (111)Si surfaces is studied and is compared with that of most used so far wet chemical cleaning. Prior oxidation the silicon surface was hydrogenated by exposure to hydrogen plasma in an rf planar unit. The substrates were k ept at the lower electrode without healing or at temperature of 100 degrees C. The oxidation was performed at 800 degrees C in dry O-2. Oxide thicknes s and refractive index were measured by ellipsometry. In the investigated t hickness range of up to about 200 Angstrom the growth rate was linear with time. The growth rate constant was smaller as compared to the case of Si su rface with wet RCA preoxidation clean only. In spite of this, for the same time periods thicker oxides were grown on plasma treated Si substrates. Pos sible explanations of the experimental observations are discussed. An estim ation of the film stress from variation of the refractive index over the ox ide thickness is used to infer the role of the stress for the oxidation kin etics. (C) 1999 Elsevier Science Ltd. All rights reserved.