A statistical model describing temperature dependent gettering of Cu in p-type Si

A model is proposed describing quantitatively the temperature dependent gettering of Cu atoms in p-type Si wafers by taking into account the densities and the binding energies of all types of occupying sites, including the gettering ones. Binding energy in this context is defined as the decrease of the formation energy from the reference energy of the Cu atom when it is located at the T-site through which Cu atoms wander through the silicon lattice. By using a statistical approach, the model allows to predict the thermal equilibrium concentration of Cu atoms in each part of a wafer structure. The calculated results show good agreement with reported experimental observations. This model can also be applied to calculate thermal equilibrium concentrations of any contaminant

TEM Observation of the Dislocations Nucleated from Cracks inside Lightly or Heavily Doped Czochralski Silicon Wafers

The crack propagation from the indent introduced with a Vickers hardness tester at room temperature and the dislocation nucleation from the cracks at 900°C inside lightly boron (B), heavily B, or heavily arsenic (As) doped Czochralski (CZ) Si wafers were investigated with transmission electron microscopy (TEM) observations. It was found that the dopant concentration and the dopant type did not significantly affect the crack propagation and the dislocation nucleation. The slip dislocations with a density of about (0.8∼2.8) × 1013/cm3 were nucleated from the cracks propagated about 10 μm in depth. Furthermore, small dislocations that nucleated with very high density and without cracks were found around the indent introduced at 1000°C

First-Principles Calculation on Initial Stage of Oxidation of Si (110)-(1 × 1) Surface

The initial stage of oxidation of an Si (110)-(1 × 1) surface was analyzed by using the first-principles calculation. Two calculation cells with different surface areas were prepared. In these cells, O atoms were located at the Si–Si bonds in the first layer (A-bonds) and at the Si–Si bonds between the first and second layers (B-bonds). We found that (i) the most stable site of one O atom was the A-bond, and (ii) an O (A-bond) –Si–O (A-bond) was the most stable for two O atoms with a coverage ratio of ox=0.06 while an O (A-bond) –Si–O (B-bond) was the most stable for ox=0.10. The stability of O (A-bond) –Si–Si–O (A-bond) was less than the structures obtained in (ii). The other calculations showed that the unoxidized A-bonds should be left when a coverage ratio of ox is close to 1. These simulations suggest that the O atoms will form clusters in the initial stage of oxidation, and the preferential oxidation will change from the A-bonds to the B-bonds up to the formation of 1 monolayer (ML) oxide. The results obtained here support the reported experimental results

Silicon single crystal growth from a melt: on the impact of dopants on the v/G criterion

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Ab initio analysis of a vacancy and a self-interstitial near single crystal silicon surfaces: implications for intrinsic point defect incorporation during crystal growth from a melt

The microscopic model of the Si (001) crystal surface was investigated by first principles calculations to clarify the properties of intrinsic point defects near the surfaces. A c(4x2) structure model was used to describe the (001) crystal surface in contact with vacuum. The calculations predict lower formation energies near the surface than in the bulk of the crystal for both types of intrinsic point defects. The tetrahedral (T)-site and the dumbbell (DB)-site, in which a Si atom is captured from the surface and forms a self-interstitial, are found as stable sites near the third atomic layer. The T-site has a barrier of 0.48 eV, whereas the DB-site has no barrier for the interstitial to penetrate into the crystal from the vacuum. Si atoms in a melt can thus migrate and reach the third layer during crystal growth. Therefore, the melt/solid interface is always a source of both vacancies and self-interstitials