Single-crystal – oriented-crystal – and epitaxy growth processes; – Processes of growth from liquid or supercritical state – Having pulling during growth
Patent
1994-09-02
1996-01-23
Kunemund, Robert
Single-crystal, oriented-crystal, and epitaxy growth processes;
Processes of growth from liquid or supercritical state
Having pulling during growth
117 38, 117932, 437 8, C30B 1520
Patent
active
054858038
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of and an apparatus for predicting, in a CZ (Czochralski) method or a FZ (floating zone) method of growing a semiconductor single crystal from a melt of a semiconductor material, especially growing a silicon single crystal from a silicon melt, on the basis of temperature distribution in the crystal and crystal growth rate, distribution and density of crystal defects which would appear in a silicon wafer made by slicing the silicon single crystal in the course of heat treatment process.
BACKGROUND ART
As for a dislocation free, silicon single crystal grown by pulling from a silicon melt by means of a CZ method or a FZ method, it has been hitherto known that swirl defects and D-defects (in case of FZ crystal) or phenomena such as ring-shaped OSF defects, abnormal oxide precipitation, and degradation in breakdown voltage of an oxide film (in case of CZ crystal) occur in the course of heat treatment process of a wafer, depending upon the crystal pulling condition or crystal pulling apparatus condition as described by Takao Abe, in Applied Physics, 59 (1990), p. 272. Any of these defects and the phenomena affect quality of a silicon wafer used as a substrate for highly integrated ICs.
Distribution and density of these defects in a silicon single crystal grown from a melt largely depend on the pulling condition of the crystal. Therefore, it has been considered that occurrence of these defects is determined at the time of crystal pulling. Therefore, these crystal defects are named generically "crystal defects determined during the crystal growth to occur" or "grown-in defects."
The grown-in defects provide a ring-shaped or disk-shaped macroscopic distribution in a section perpendicular to the growth axis of the crystal. It has been an important subject of research in the pulling technique of CZ and FZ silicon single crystals for a long time to elucidate the generation mechanism of the macroscopic shape.
As for such grown-in defects, it has been a dominant view that point defects such as interstitial atoms and atom vacancies taken into the crystal from the crystal growth interface during the crystal growth become thermally superfluous, agglomerate, and form nuclei of the grown-in defects as described by Takao Abe, in "Applied Physics," 59 (1990), p. 272. Therefore, it has been considered that the peculiar distribution shape of grown-in defects can be explained in terms of diffusion of interstitial atoms and atom vacancies and reaction between interstitial atoms and atom vacancies in the silicon crystal in the course of crystal pulling. (See V. V. Vronkov, J. Cryst. Growth, 59 (1982), p. 625; T. Y. Tan and U. Gosel, Appl. Phys. A37 (1985), p. 1; and W. Wijiaranakula, J. Electrochem. Soc., 139 (1992), p. 604.) In the existing circumstances, however, the diffusion equation of interstitial atoms and atom vacancies capable of determining on the basis of crystal growth condition, the shape in distribution of grown-in defects observed in CZ and FZ silicon crystals has not yet been established as pointed out by K. Sumino, in Materials Science Forum, Vol. 105-110 (1992) Pt. 1, pp. 139-160, EDs. Zs Kajcsos & Cs Szeles, Trans. Tech. Publications.
DISCLOSURE OF INVENTION
Therefore, an object of the present invention is to provide a method of and an apparatus for logically predicting, in the production process for fabricating a silicon wafer for semiconductor from a dislocation free, silicon single crystal grown from a melt, on the basis of actual data indicating the temperature distribution in the crystal and crystal growth rate in the course of crystal pulling, distribution of grown-in defects which would appear in wafer during a heat treatment.
The present inventor has experimentally found that uphill diffusion of interstitial atoms and atom vacancies toward the crystal growth interface, which depends on the temperature gradient existing in the crystal during crystal growth, occurs dominantly during crystal growth as compared with ordinary diffusion of interst
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Morozov et al, "Use of Precision Density and Lattice Parameters Measurements for Study . . . " Jour. of Crystal Growth vol. 75 (1986) pp. 491-496.
Applied Physics 59 (19909), T. Abe, p. 272.
The Mechanism of Swirl Defects Formation in Silicon, V. Voronkov, Journal of Crystal Growth 59 (1982) pp. 625-643.
Point Defects, Diffusion Processes, and Swirl Defect Formation in Silicon, T. Tan et al., Appl. Phys. A 37, 1-17 (1985).
Numerical Modeling of the Point Defect Aggregation during the Czochralski Silicon Crystal Growth, W. Wijaranakula, J. Electrochem Soc., vol. 139, No. 2, Feb. 1992, p. 604.
Current Problems of Defects in Semiconductors-Interaction of Defects with Impurities, K. Sumino, Materials Science Forum, vol. 105-110 (1992) pp. 139-159.
Oxygen Precipitation Mechanism in CZ Silicon, N. Inoue et al., Appl. Phys. vol. 48, No. 12 (1979) pp. 1126-1141.
Kunemund Robert
Nippon Steel Corporation
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