Grown-in Microdefects in a Slowly Grown Czochralski Silicon Crystal Observed by Synchrotron Radiation Topography

Abstract

Grown-in microdefects of a slowly grown Czochralski (CZ) silicon crystal were studied by short wavelength synchrotron radiation topography and successfully visualized. It was shown that the microdefects had spherical strain fields, by comparing the defect images in the two topographs taken with the Bragg reflections perpendicular and parallel to the growth direction. The radial distributions of the microdefect size and density were measured from the defect images in the topographs. The misfit volume of the microdefects was approximately 1 ×10-12 cm3 at the central axis region of the crystal ingot, and decreased monotonically toward the peripheral region of the crystal. The density of the microdefects was approximately 300/cm3 at the center of the crystal, increased toward the periphery and then decreased rapidly to almost zero in the very peripheral region approximately 7 mm from the surface of the crystal ingot. These radial distributions are discussed in connection with the self-interstitial atoms of silicon crystals.

Physical Model of Paths of Microdefects Nucleation in Dislocation-Free Single Crystals Float-Zone Silicon

“…This result is well correlate with data of Ref. [26]. Such impurities as oxygen [37,55,[68][69][70][71][72][73] and carbon [12,28,67,[74][75][76][77][78] which are found in high concentrations in FZ silicon [79] render direct effect on process of formation of defects.…”

“…[21] as well as results of Refs. [14,[18][19][20] also are confirmed by other recent researches [22][23][24][25][26]. Many of these Refs.…”

“…Furthermore, Voronkov's theory does not take into account the influence of carbon to process of formation of microdefects. The participation of carbon during defect formation results in a conclusion about a heterogeneous character of nucleation of microdefects [23,26,41]. Therefore, the purpose of our paper is the development of an optimum physical model of formation, growth and transformation of microdefects in FZ silicon.…”

About the simulation of primary grown-in microdefects in dislocation-free silicon single-crystal formation

“…However, the model of point-defect dynamics cannot explain the large amount of experimental research into the defect structure of dislocation-free Si monocrystals. It follows from experiment that oxygen and carbon play a dominant role in the formation of grown-in microdefects in large-scale CZ-Si monocrystals [27][28][29][30]. Local maxima of microdefect concentrations coincide with areas of phosphor in high concentration [23].…”

Classification of microdefects in semiconducting silicon

“…Another group of authors, on the grounds of their experimental results, adhere to the opposite viewpoint [2123, 33,34]. In [35] an assumption was made that the formation mechanism of grown-in microdefects is mostly influenced by the joint agglomeration of self-interstitials and carbon atoms (found in LST-defects [36]) instead of oxygen precipitation. Similar results were obtained in [37], where it was shown that OSF-rings are formed as per heterogeneous mechanism under simultaneous oxygen precipitation and agglomeration of silicon self-interstitials with atoms of non-oxygen impurity.…”