Effect of stresses on the diffusion of impurities in the process of laser solid-phase alloying of silicon

• Published in: Materials science (New York, N.Y.) Vol. 36; no. 3; pp. 333 - 339
• Main Authors: Bonchyk, O. Yu, Kyyak, S. H., Pokhmurs’ka, H. V., Fl’orko, O. V., Chekurin, V. F.
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01-05-2000
• Subjects: Alloying; Concentration gradient; Crystal lattices; Diffusion layers; Impurities; Infrared heating; Infrared lasers; Infrared radiation; Laser beam heating; Lasers; Mathematical models; Power; Residual stress; Silicon; Silicon wafers; Single crystals; Solid phases; Strain; Yield point
• ISSN: 1068-820X; 1573-885X
• DOI: 10.1007/BF02769594

We describe some results of experimental and theoretical investigations of diffusion of impurities into single-crystal silicon wafers under the action of laser infrared radiation and the effect of stresses on this process. We consider laser heating of a wafer by means of the irradiation of its entire surface with a uniform beam or scanning of the surface with a narrow beam. In the second case, temperature stresses attain the yield point of the material, which is corroborated by significant distortions of its crystal lattice and by residual stresses. We propose a mathematical model for the description of mechanothermo-diffusion processes, which well fits the shape of experimental diffusion curves. Our investigations have shown some ways of purposefully influencing the properties of diffusion layers, in particular, their concentration profile. If, in the course of alloying, one creates elastic strain varying across the thickness, it becomes possible, depending on the sign of the strain gradient, to bring the maximum of the concentration curve nearer to the wafer surface or to remove this maximum from it.