Papers by Keyword: Cz Growth

Abstract: The numerical modeling of melt flow, heat transfer and impurity (phosphorus) diffusion in the double crucible of "Redmet-90M" Cz puller was carried out in an application to a 200 mm diameter Si single crystal growth. The double crucible consists of two coaxial crucibles having different sizes: 490 mm (external) and 300 mm (internal) inner diameters. The bottom of internal crucible has a central hole of Do = 6 and 12 mm diameter for melt inflow from the external crucible. During crystal pulling the granulated Si was added in the external crucible and a melt of the internal crucible was doped by phosphorus. Three-dimensional features of a rotating melt flow affecting on heat transfer and impurity diffusion in the internal crucible were analyzed. In particular, the melt precession and thermal asymmetry near the liquid-solid interface (LSI) in the internal crucible are discussed. It is shown that a significant phosphorus losses caused by its evaporation from a melt surface may be compensated by additional phosphorus doping in the internal crucible.

Abstract: In an application to large diameter Czochralski (CZ) silicon (Si) single crystal growing the influence on crystal temperature field of various thermal shield assemblies located near to its surface is discussed. By means of mathematical modeling the computer model of thermal processes in an application to a hot zone of "Redmet-90" puller [1], intended for 200 and 300 mm diameter Si single crystal growth is developed. The role of the ring shield and the shield assembly, consisting of two shields (an internal cone and an external one is repeating the crucible shape) and being as a basis of some patents, is investigated. On the basis of the carried out calculations the new thermal shield assembly for "Redmet-90" puller was offered. Its influence on formation of the characteristic thermal zones in growing single crystal, corresponding to defect formation processes in dislocation-free Si crystals (the recombination of intrinsic point defect – IPD, and the formation of their agglomerates) is discussed. The influence of a melt flow on the liquid/solid interface (LSI) shape and thermal stability of crystal growing process is analyzed.

Abstract: The features of microdefect formation during dislocation-free Si single crystals are considered in connection with the specific thermal CZ growing conditions. For this purpose the thermal crystal growth histories are calculated by means of a global thermal mathematical model and then on their basis the intrinsic point defect recombination and microdefect formation are modeled numerically. Difficulty of such integrated approach is explained by of the complicated and conjugated thermal modeling and a presence of various temperature zones in growing single crystal, answering to various defect formation mechanisms.