Concentration, Solubility, and Equilibrium Distribution Coefficient of Nitrogen and Oxygen in Semiconductor Silicon

Abstract

The concentration of nitrogen and oxygen in semiconductor silicon and their solubilities in silicon at its melting point have been measured by charged particle activation analysis and infrared spectrophotometry. It has been found that: (i) commercial semiconductor silicon contains less than 1×1015 normalatoms/cm3 of nitrogen in the un‐ionized state; (ii) the solubility in solid silicon is 4.5±1.0×1015 normalatoms/cm3 for nitrogen and 2.75±0.15×1018 normalatoms/cm3 for oxygen; and (iii) the solubility in liquid silicon is about 6×1018 normalatoms/cm3 for nitrogen and 2.20±0.15×1018 normalatoms/cm3 for oxygen. Thus, the equilibrium distribution coefficient has been determined to be about 7×10−4 for nitrogen and 1.25±0.17 for oxygen. The solubilities of the two elements are compared with those of other elements, especially carbon, and are discussed thermochemically.

Solubilities and Equilibrium Distribution Coefficients of Oxygen and Carbon in Silicon

“…The comparison of the reported 5,11,24,[30][31][32][33][34] and present oxygen solubilities in solid silicon equilibrated with silica is shown in Fig. 6.…”

“…Several research groups 24,[32][33][34] evaluated the oxygen solubility by measuring the oxygen concentration profiles in the solid silicon after heating in various atmospheres. Yatsurugi et al 5) and Huang et al 11) measured the oxygen contents in the solid silicon crystals grown by a zone melting method in an oxygen atmosphere and a vertical freezing method in a silica ampoule, respectively. Hrostowski and Kaiser, 30) and Bean and Newman 31) annealed the CZ solid silicon crystals containing 1.4-1.6 × 10 18 atoms·cm −3 as initial oxygen, and then measured the concentrations of soluble oxygen in the solid silicon using IR absorption method.…”

“…Therefore, the solubility values of oxygen (C Table 2. In the experimental studies by other research groups, [5][6][7][8][9][10][11] the specimens for oxygen analysis were prepared by the crystalgrowth-related techniques. Kakimoto and Ozoe, 39) however, clarified that surface-tension-driven flow affected the oxygen distribution at the interface between crystal and melt.…”

“…The reported equilibrium distribution coefficients of oxygen ranged widely from 0.2 to 1.25, [4][5][6][7][8][9][10][11][12] and the values of the equilibrium distribution coefficient of carbon were reported to be less than 0.1. [13][14][15][16] The crystal-growthrelated techniques, such as the zone melting process and the CZ process, were employed to prepare the specimens for oxygen or carbon analysis in the experimental studies on the distribution.…”

“…[13][14][15][16] The crystal-growthrelated techniques, such as the zone melting process and the CZ process, were employed to prepare the specimens for oxygen or carbon analysis in the experimental studies on the distribution. [5][6][7][8][9][10][11]14) The equilibrium distribution of oxygen or carbon between crystal and melt has been assumed in these studies.…”