Diffusion-driven precipitate growth and ripening of oxygen precipitates in boron doped silicon by dynamical x-ray diffraction

Abstract

X-ray Pendellösung fringes from three silicon single crystals measured at 900 °C are analyzed with respect to density and size of oxygen precipitates within a diffusion-driven growth model and compared with TEM investigations. It appears that boron doped (p+) material shows a higher precipitate density and a higher strain than moderately (p-) boron crystals. In-situ diffraction reveals a diffusion-driven precipitate growth followed by a second growth regime in both materials. An interpretation of the second growth regime in terms of Ostwald ripening yields surface energy values (around 70 erg/cm2) similar to published data. Further, an increased nucleation rate by a factor of ∼13 is found in the p+ sample as compared to a p- sample at a nucleation temperature of 450 °C.

Growth and nucleation regimes in boron doped silicon by dynamical x-ray diffraction

“…As shown previously in Ref. 21, this yield within the model of spherical precipitates a higher linear misfit strain e in the p þ sample as compared to pÀ material.…”

“…The feature that pþ samples show a higher e and thus higher aspect ratio holds for all specimens presented here and in Ref. 21. Even though the difference in e in the sample set without nucleation step at 450 C is quite small.…”

“…care of a possible second growth regime as observed in Ref. 21 and interpreted as Ostwald ripening. 33,34 The signal evolution of the specimens with a nucleation step can be described with a combination of a diffusion driven growth process in the time range from 1-11 h (p þ I) to 6-46 h (p À I) (see Figure 3 red lines), followed by a second growth regime with a t 1/3 power law (black lines).…”

“…Moreover, the precipitate density after a nucleation step at 450 C is about a factor of 13 higher in pþ as compared to pÀ material. 21 In this paper, a deeper insight into the O kinetics in pþ Si compared to pÀ material is presented by comparing the precipitation behavior at 780 C with and without a nucleation step at 450 C. Four crystal wedges (see Table I) were prepared and the thickness dependence of the 400 Bragg reflection was investigated in-situ at 780 C by the Pendell€ osung method. 22,23 The diffraction energy was 59.3 keV, which corresponds to the K a1 -line of the tungsten X-ray tube.…”

Misfit strain of oxygen precipitates in Czochralski silicon studied with energy-dispersive X-ray diffraction

“…29 It also is in contradiction to the effective constrained misfit of platelets determined in a previous work where e plate was found to be 0.193 by evaluating thickness dependent Pendell€ osung oscillations in combination with TEM data 7 and to the results of a more recent work 30 utilizing the same technique where it was found that the higher the aspect ratio the lower e plate . Therefore, it has to be questioned if the precipitate population in these two samples is sufficiently characterized and respected in the evaluation.…”