Oxygen precipitation in silicon: Experimental studies and theoretical investigations within the classical theory of nucleation

Abstract

Quantitative measurements of the oxygen precipitate rate as a function of annealing were made in Czochralski-grown silicon wafers that contained different initial concentrations of oxygen. All wafers were annealed at 1000 °C for 15 min to ensure that the initial cluster-size distributions were identical in all samples of the same composition prior to the multi-step annealing treatments used for the precipitation studies. The experimental data are compared with numerical predictions for time-dependent nucleation within the classical theory of nucleation. Quantitative agreement is obtained between the measured and calculated densities of oxygen precipitates for nucleation temperatures greater than 600 °C, but only over a narrow range of oxygen composition. Below 600 °C, the measured density for all samples is orders of magnitude larger than is predicted from the model. Further, the measured data show an anomalously small temperature dependence for the induction time for nucleation that does not scale with the diffusion coefficient, as expected from the classical theory of nucleation. Fundamentally, the classical theory of nucleation cannot explain the time-dependent nucleation of oxygen precipitates for temperatures below 650 °C. A possible reason is given.

Investigating thermal donors in n-type Cz silicon with carrier density imaging

“…7 reveals the O i concentration in the wafer after TD annihilation rather than the total oxygen concentration. The oxygen particles in the P-band did not dissolve at 800 • C and therefore the oxygen from these particles did not contribute to TD growth at 450 • C. Higher temperature anneal, such as homogenization anneal for 15min at 1000 • C, 17 is required to dissolve grown-in oxide particles and the mapping of the total oxygen concentration could be performed using the same procedure as presented above. As shown in Fig.…”

Quantitative copper measurement in oxidized p-type silicon wafers using microwave photoconductivity decay

“…8 The density of oxide precipitates after 4 h and 16 h nucleation is approximately 5 ϫ 10 8 and 10 10 cm −3 , respectively. 9 In the remainder of the letter, we will refer to these wafer groups as "homogenized", "low BMD", and "high BMD" wafers.…”

Thermal stability of internal gettering of iron in silicon and its impact on optimization of gettering

“…The wafer was first annealed at 1230°C to dissolve all oxygen clusters and then subjected to oxygen nucleation treatments at 650°C for 14 h followed by 4 h 800°C and 16 h 1000°C growth steps. Well-defined oxide precipitates, 11 with a density of approximately 5 ϫ10 9 cm Ϫ3 were obtained, which was confirmed by preferential etching and then counting the pits. Based on the density of the oxide precipitates and the decrease in interstitial oxygen concentration, assuming spherical SiO 2 precipitates with oxygen atomic concentration of C p ϭ4.6ϫ10…”

“…In this set of simulations, the total iron concentration in the sample is set to be 1ϫ10 11 cm Ϫ3 . The initial condition and ramping profiles were the same as in Figs.…”