Investigation of solid planar sources for phosphorus and arsenic doping of silicon

摘要

New materials systems for phosphorus and arsenic solid planar diffusion sources have been investigated. Phosphosilicate gel, aluminum metaphosphate, and yttrium metaphosphate were investigated for a phosphorus solid planar source. For an arsenic solid planar source, gallium arsenate and arsenosilicate gel were investigated. The kinetics of vaporization from gels, the microstructural changes of the gel during heat treatment, and the doping performance have been investigated. The phophosilicate gel with 56 mol% P$sb{2}$O$sb{5}$ concentration appeared to be most suitable among other phophosilicate gels for a low temperature, phosphorus solid planar source. Surface concentrations equal to solid solubility limits could not be produced in silicon using the aluminum metaphosphate source in the low temperature region. The yttrium metaphosphate source appeared to be useful as a high temperature solid planar source to form deep junctions in silicon. Higher oxygen partial pressure developed by the gallium arsenate source, compared to that of the aluminum arsenate source that is commercially used as a low temperature source, results in higher sheet resistances from the gallium arsenate source than from the aluminum arsenate source. The vaporization rate from arsenosilicate gels was not appropriate for a predeposition process.