星野 忠次

The S(B) step growth mechanism on (001) surfaces of diamond structure crystals was elucidated precisely. This S(B) step growth occurs as the following process: [GRAPHICS] The process of filling the missing dimer at the S(B) step type I edge was investigated in detail by using quantum chemical calculation. Because the S(B) step type I has a diene structure, two stable positions are available for migrating adatoms at the edge of the S(B) step type I. When two adatoms occupy the two stable positions, a dimer cluster is formed and migrates to fill the missing dimer and a normal S(B) step type I structure is reproduced. Since the potential energy barriers appearing in the processes of a single adatom and the subsequent cluster migrations at the S(B) step type I with a missing dimer are lower than that which appeared in the single adatom migration process along the dimer rows on terraces of (001) surfaces, the filling of the missing dimer occurs easily in the S(B) step growth. (C) 1998 Elsevier Science B.V. All rights reserved.

Potential energy hypersurfaces of the nitrogen elimination and the Wolff rearrangement were investigated for both cyclic and open-chain 2-diazoketones by means of semi-empirical MINDO/3 molecular orbital calculations with configuration interaction. A new mechanism of the Wolff rearrangement was proposed as in Fig. 14(b). This mechanism explains experiments well while the old mechanism (Fig. 14(a)) is inconsistent with experiments occasionally. It was concluded that the photochemical reaction of the diazonaphthoquinone-novolac resist mainly taking place in micro-lithography process is one-step ketene formation as shown in Fig. 1(c).(10/12).

Potential energy hypersurfaces of the nitrogen elimination and the Wolff rearrangement were investigated for both cyclic and open-chain 2-diazoketones by means of semi-empirical MINDO/3 molecular orbital calculations with configuration interaction. A new mechanism of the Wolff rearrangement was proposed as in Fig. 14(b). This mechanism explains experiments well while the old mechanism (Fig. 14(a)) is inconsistent with experiments occasionally. It was concluded that the photochemical reaction of the diazonaphthoquinone-novolac resist mainly taking place in micro-lithography process is one-step ketene formation as shown in Fig. 1(c).(10/12).

The adsorption reaction of O2 molecule with symmetric dimers on the Si(001)-2×1 reconstructed surface has been investigated by ab initio molecular orbital calculations. Detailed analysis of the lowest energy reaction path has revealed that there exists a metastable state in which O2 molecule adsorbs on silicon dimer without dissociation, the dissociation of O2 molecule requires large activation energy, and a silicon oxide and an isolated oxygen atom are produced after the reaction has been completed. The activation energy required for the conversion from the metastable state to the final products has been estimated to be 60.4 kcal/mol. This result suggests that a symmetric dimer on the Si(001)-2×1 surface is hardly oxidized at room temperature. This conclusion is consistent with the recent STM observations that the initial stage of oxidation starts from the dimer defect sites on the Si(001) surface. On the contrary, it has been found that no activation energy is required for the oxidation reaction by O atom.