Computer simulation of point-defect fields and microdefect patterns in Czochralski-grown Si crystals

Computer simulation of the point-defect fields in Czochralski Si crystals is reported. Our model includes the following factors: for crystals, variable pull rate V(t), the lagging of crystallization rate Ṽ behind V, crystal length increasing with time l(t), temperature field T(r, z) dependent on l or Ṽ, and actual shape of the crystal-melt interface; for native point defects, transport with the moving crystal, Fickian diffusion and thermodiffusion, the vacancy-self-interstitial recombination, and annealing at the crystal surface. Temperature fields established during crystal growth are calculated using a global model of heat transfer in the system. Important cases of variable V and pulling halts are considered. Simulations successfully reproduce experimental data such as the shape and position of the interstitial and vacancy regions, including the R-OSF bands. The values of model constants, except for the critical point-defect concentrations, are the same as those obtained for pedestal Si crystals.