Germanium-doped Czochralski Silicon Research Articles

Germanium in Czochralski Silicon

The behaviors of isovalent impurities doped in Czochralski (CZ) silicon crystal have attracted considerable attention in recent years. In this article, a review concerning recent processes in the study about germanium in CZ silicon is presented. The disturbance of silicon crystal lattice in and the influence on the mechanical strength due to germanium doping is described. Oxygen related donors, oxygen precipitation and voids defects in germanium doped Czochralski (GCZ) silicon has been demonstrated in detail. In addition, the denuded zone formation and the internal gettering technology of GCZ silicon is also discussed.

Germanium effect on oxygen precipitation in Czochralski silicon

The oxygen precipitation in germanium-doped Czochralski (GCZ) silicon has been investigated. After a prolonged annealing at 800 and 1000°C, it was found that the Ge-doping enhanced the formation of oxygen precipitates with a higher density and modified their morphology and size. Furthermore, the existing oxygen precipitates in the GCZ silicon were readily dissolved, because the Ge-doping facilitated the formation of smaller oxygen precipitates. Based on the facts, the mechanism for the enhancement effect of Ge-doping on oxygen precipitation has been preliminarily discussed.

Intrinsic gettering in germanium-doped Czochralski crystal silicon crystals

The intrinsic gettering (IG) of germanium-doped Czochralski (GCZ) silicon with different concentrations of germanium has been investigated in this paper. The conventional Czochralski (CZ) and the GCZ silicon samples were annealed using a one-step high temperature process followed by a sequence of low–high temperature annealing cycles. It was found that the good defect-free denude zones in the near surface of the GCZ silicon could be achieved using simply a one-step high temperature annealing process. Furthermore, the density of bulk microdefects as IG sites was higher than that in the CZ silicon, as a result of germanium enhancing oxygen precipitation during three-step annealing. Meanwhile, the experimental results showed that germanium also enhanced the out-diffusion of oxygen. Furthermore, it is believed that germanium doping can increase the ability of IG in CZ silicon wafers.