Defect dynamics in the presence of nitrogen in growing Czochralski silicon crystals

Abstract

Many crystallographic imperfections termed microdefects form in silicon crystals during their Czochralski growth. These are the aggregates of vacancies, of self-interstitials, or of oxygen (silicon dioxide). The distribution of microdefects can be strongly influenced and controlled by the addition of impurities such as nitrogen to the crystal. A model describing the Czochralski defect dynamics in the presence of nitrogen and oxygen is proposed and solved. The reactions between vacancies and self-interstitials, nitrogen monomers and dimers, nitrogen and vacancies, and the reactions involving vacancies, oxygen, and complexes of vacancies and oxygen are incorporated, along with the formation of various microdefects. All microdefects are approximated as spherical clusters. The formation of all clusters is described by the classical nucleation theory. The clusters, once formed, grow by diffusion-limited kinetics. The microdefect distributions in Czochralski crystals growing under steady state as well as unsteady state are discussed. r

A Selective Review of the Simulation of the Defect Structure of Dislocation-Free Silicon Single Crystals

“…Free and bound (VO and VO 2 ) vacancies are expended initially on the formation of microvoids (1223 K< T 1423 K) and then are expended on the formation of Oclusters (precipitates of oxygen) at T < 1223 K [42]. Exactly the same approach applies to nitrogen impurity with similar results of calculations [43]. In the articles [42,43] ignored the effect of impurities on the formation of interstitial grown-in microdefects.…”

Defect Structure of Nitrogen Doped Czochralski Silicon Annealed under Enhanced Pressure

“…The presence of nitrogen affects strongly the kind and distribution of such oxygen-containing microdefects; only small oxygen-containing clusters are formed at processing of Cz-Si:N [2]. Similarly as in the case of nitrogen-lean Cz-Si, clustering/precipitation of O i 's in Cz-Si:N at enhanced temperatures (HT) depends also on hydrostatic pressure (HP) applied at processing [3].…”

The Diffusion Model of Grown-In Microdefects Formation During Crystallization of Dislocation-Free Silicon Single Crystals

“…After the formation of microvoids, the aforementioned complexes grow and take up vacancies. This model has ignored the growth of the complexes by means of the injection of intrinsic interstitial silicon atoms and the interaction of an impurity with intrinsic interstitial silicon atoms (Kulkarni 2007;2008b).In the general case recombination-diffusion model assumes that the process of defect formation in dislocation-free silicon single crystals occurs in four stages: (i) fast recombination of intrinsic point defects near the crystallization front; (ii) the formation in the narrow temperature range 1423...1223 K depending on the value of V g /G microvoids or interstitial dislocation loops; (iii) the formation of oxygen clusters in the temperature range 1223...1023 K; (iv) growth of precipitates as a result of subsequent heat treatments.Recombination-diffusion model is the physical basis for models of the dynamics of point defects. The mathematical model of point defect dynamics in silicon quantitatively explains the homogeneous mechanism of formation of microvoids and dislocation loops.…”

“…al., 2004). R e c e n t v e r s i o n s o f t h i s m o d e l h a v e s u g g e s t e d t h a t p a r t o f t h e v a c a n c i e s ( v ) i n t h e temperature range 1683 ... 1373 K, due to the interaction with oxygen (O) and nitrogen (N) impurities, are bound into complexes of the vO, vO 2 , and vN types (Kulkarni 2007;2008b). After the formation of microvoids, the aforementioned complexes grow and take up vacancies.…”

“…After the formation of microvoids, the aforementioned complexes grow and take up vacancies. This model has ignored the growth of the complexes by means of the injection of intrinsic interstitial silicon atoms and the interaction of an impurity with intrinsic interstitial silicon atoms (Kulkarni 2007;2008b).…”