Characterization of Hydrogen in Epitaxial Silicon Films Grown at Very Low Temperatures

Abstract

Experimental and theoretical analyses of hydrogen atoms incorporated in epitaxial silicon films grown at very low temperatures were investigated using a high resolution X-ray diffractometer (HRXRD) and an ab-initio total energy calculation. We found that the lattice constant of the epitaxial films was expanded by the H atoms and this lattice expansion occurred only in a direction normal to the surface. We proposed the Si–H–Si configuration as a model to explain the lattice expansion phenomenon. The results of the calculation supported this model and also suggested that the microscopic stress was introduced by the H atom in the configuration. In B-doped epitaxial Si films, the B atoms were 100% neutralized by the H atoms and activated by thermal annealing. We increased the growth temperature to overcome these H related problems and succeeded in controlling the H incorporation. The B-doped Si film with a hole concentration of 1.7×1019 cm-3 was obtained at a growth temperature of 240°C.