Consumption kinetics of Si atoms during growth and decomposition of very thin oxide on Si(001) surfaces

Ogawa, Shuichi*; Yoshigoe, Akitaka ; Ishizuka, Shinji*; Teraoka, Yuden; Takakuwa, Yuji*

The surface morphological change during growth and subsequent decomposition of very thin oxide on Si(001) surface was observed in real time by RHEED combined with AES and macroscopically by STM. The RHEED intensity ratio between half-order spots revealed that etching of the surface took place in a manner of nucleation and lateral growth of dimer vacancy on the terrace during two-dimensional (2D) oxide island growth at 690C, whereas the resultant oxide layer was decomposed at 709C with consumption of Si atom in a step flow mode. STM observation of the partially oxide decomposed surface, however, showed that a number of Si islands with 10-20 angstrom in diameter remained randomly over the rather atomically flat terraces within voids in spite of the step-flow etching. These results are considered in terms of the phase separation of Si-rich oxide grown by 2D oxide island growth mode between Si clusters and a stoichiometric SiO matrix and subsequent precipitation of Si islands on the terrace during decomposition.