Growth and characterization of heavily doped silicon crystals

Abstract

Silicon crystals grown with the Czochralski method are still the most common material used for the production of electronic devices. In recent years, a growing need of large diameter crystals with increasingly higher doping levels is observed, especially to support the expanding market of discrete devices and its trend towards lower and lower resistivity levels for the silicon substrate. The growth of such heavily doped, largediameter crystals poses several new challenges to the crystal grower, and the presence of a high dopant concentration in the crystal affects significantly its main properties, requiring also the development of dedicated characterization techniques. This paper illustrates the recent advances in the growth and characterization of silicon crystals heavily doped with antimony, arsenic, phosphorus and boron.

Czochralski Growth of Silicon Crystals

“…Such high doping concentrations are needed for certain applications of Si crystals in power electronics [80]. In such cases, the enrichment of the solute in front of the interface results in a locally dependent liquidus temperature; in combination with the diffusion boundary layer, this can lead to the phenomenon of constitutional supercooling-a morphological instability of the melt-crystal interface (cellular structure, in Si with microfacets).…”

Constitutional Supercooling in Czochralski Growth οf Heavily Doped Silicon Crystals

“…Thereby, it must be taken into account that the values of the diffusion coecients D reported for the various doping elements in literature can vary strongly depending of the doping element [6,22], for example in case of phosphorus between 2.05.1×10 Table II …”

“…[6,12,15]. Therefore, it will remain dicult to prove in a certain case whether constitutional supercooling is responsible for a structure loss or whether other phenomena were limiting the dislocation-free growth of heavily doped silicon crystals by the Czochralski technique.…”

“…[35] which are diering considerably from the doping techniques used for standard or shallow doping levels in CZ growth of silicon. The typical resistivity ranges which are feasible today are 0.520 mΩ cm for boron, 12 mΩ cm for phosphorus, and 210 mΩ cm for arsenic [6].…”

Low-resistivity bulk silicon prepared by hot-pressing boron- and phosphorus-hyperdoped silicon nanocrystals

“…3 At present the low-resistivity ranges are typically 0.5 − 20 and 1 − 2 mΩ•cm for B-and P-doped bulk Si, respectively. 4 Low-resistivity bulk Si is usually obtained by the Czochralski growth of Si ingots with doping levels approaching the solubility limits of dopants. [5][6][7][8] The very high doping levels significantly complicate the growth of Si ingots, rendering relatively high cost for low-resistivity bulk Si.…”