Cz-Si Single Crystals Research Articles

Evaluation of numerical simulation of constitutional supercooling during heavily Boron-Doped silicon crystal growth using Cz method

Using the Czochralski (Cz) method, it has been established that heavily doped silicon (Si) single crystals with impurities such as boron (B) can negatively impact the quality of grown crystals due to morphological instabilities such as cellular growth caused by constitutional supercooling for doping higher than 1 × 1019 cm−3. To produce high-quality heavily doped Si single crystals, constitutional supercooling must be prevented during growth. In this study, we used a three-dimensional numerical simulation to predict constitutional supercooling during the growth of heavily B-doped Cz-Si single crystals, considering the transport of B in the melt and the segregation effect. We compared the numerically predicted constitutional supercooling region with experimental data to assess its accuracy and found that the cellular growth region observed in the experiment was in good agreement with the region of constitutional supercooling predicted by the simulation. Moreover, we considered the effects of different pulling rates and crystal lengths during the growth process on constitutional supercooling, and the limitations of numerical modelling.

Perspective semiconductor materials for the using in the power electronics

The world market of discrete power devices in 2024 will be ~ $ 23 billion, the share of devices based on silicon will be ~ 87%, due to the price availability and the mastery of silicon technologies. The inflow of investments, the success in mastering SiC, GaN, diamond, heterostructure technologies, and the pressing need for the manufacture of new high-temperature, radiation-resistant power semiconductor devices (PSs) with better performance and frequency characteristics, in comparison with silicon devices, contribute to the growing popularity of these materials from manufacturers of devices. The pressure of legislative and commercial requirements related to energy efficiency and cost reduction contributes to the successful development of a new element base using these materials for the fifth generation (5G) communication networks, broadband Internet access systems, satellite systems, microwave transmitters, civil and military radar stations, for energy and transport. However, the possibilities of silicon in terms of increasing thermostability, radiation resistance, reliability of PSs and industrial development are far from exhaustion. Methods for the special alloying of CZ-Si single crystals and for processing, improving the mechanical properties of single crystals, as well as evidence of an increase in the radiation and thermal stability of silicon-based PSs are proposed.

Structural changes in Cz-Si single crystals irradiated with high-energy electrons from data of high-resolution X-ray diffractometry

Structural changes in Cz-Si single crystals irradiated with high-energy electrons from data of high-resolution X-ray diffractometry

Influence of crystalline defects in Czochralski-grown Si multicrystal on minority carrier lifetime

Si multicrystals have been grown by the Czochralski (CZ) method using commercially available semiconductor grade Si raw material (11N) and high purity silica crucibles for investigating the influence of crystalline defects such as grain boundaries including sub-grain-boundaries, and high-density dislocations on the minority carrier lifetime. The minority carrier lifetime in the CZ-Si multicrystal was compared with that in a CZ-Si single crystal, both with and without intentional Fe doping. It was found that the minority carrier lifetime in regions with high density of crystalline defects in the CZ-Si multicrystal decreased drastically to 1 μs from 8 μs, which was the value in the CZ-Si single crystal. Fe doping with a concentration of 3×10 13 atoms/cm 3 decreased the minority carrier lifetime to 2 μs in the CZ-Si single crystal. We therefore conclude that both crystalline defects and Fe doping play a very important role in the deterioration of the minority carrier lifetime, and the influence of the crystalline defects is more crucial by considering that the occurrence of crystalline defects in a multicrystal is an intrinsic problem whereas Fe contamination is an extrinsic one.

Determination of dominant type of defects in Cz-Si single crystals after irradiation with high-energy electrons

Theoretical and experimental studies of silicon crystals irradiated with high- energy electrons (Е = 18 MeV) were made using the method of full integral X-ray reflectivity. To explain peculiarities of full integral reflectivity behaviour versus radiation dose and the order of reflection, the relationships of generalized dynamic theory of the Bragg X-ray diffraction in crystal comprising several defect types were used. The presence of several types of dominant defects in crystals allows closer tracing the dynamics of full integral reflectivity change versus the order of reflection and radiation dose, as well as estimating the contribution of each defect type to the diffusion component of X-ray scattering.

In situ observation of iron atoms in multicrystalline silicon at 1273 and 300 K by Mössbauer spectroscopy

57Fe Mössbauer absorber experiments are performed at 1273 and 300 K on two different samples of multicrystalline Si (mc-Si), whose minority carrier lifetimes are 41 and 1.5 μs, respectively. The samples are deposited with 1.5 nm 57Fe, and are annealed and measured simultaneously at 1273 K for 1 week. The spectra consist of four singlets at 1273 K, and of three singlets at 300 K. Comparing the present results with those from 57Fe-deposited CZ-Si single crystal, the 57Fe atoms are found to exist in the mc-Si matrix dominantly as substitutional Fe atoms and different Fe-defect clusters, but not as FeSi 2 precipitates. One of the components at 1273 K, which yields an isomer shift of 1.1 mm s −1, appears to be due to interstitial Fe atoms trapped on defects. The fraction depends clearly on the minority carrier lifetime, and therefore, on the quality of the mc-Si samples.

Infrared measurement of Ge concentration in CZ–Si

High concentration Ge-doped in CZ–Si single crystals were measured by Fourier transform infrared spectroscopy (FTIR) at room temperature (RT) and 10 K together with the SEM-energy dispersive X-ray (EDX) spectroscopy. We make use of the new peak that appears at the wave number of 710 cm −1. This peak becomes clearer with increasing concentration of Ge, the relation between absorption coefficient ( α max ), half-peak breadth ( W 1/2) and Ge concentration is determined. And the formulas of determining Ge concentration in CZ–Si single crystals by means of FTIR technology have been given at RT and 10 K. The result of error analysis indicates that FTIR technology is capable of determining the Ge concentration in CZ–Si single crystal.

Nitrogen-doping effect in a fast-pulled Cz-Si single crystal

In the nitrogen-doped and fast-pulled crystals, the nitrogen plays a role to disturb the growth of vacancy clusters by reducing the vacancy-rich region and the vacancy concentration. Thus, the oxidation-induced stacking fault ring (OSF-ring) is formed near the edge region and its width depends on the nitrogen-doping concentration. The vacancy clustering is severely suppressed and the increased residual vacancy causes the anomalous oxygen precipitation. A conceptual model based on the reduction of point defect concentration could explain the nitrogen-doping effects.

Er–O clustering and its influence on the lattice sites of Er in Si

We present emission channeling experiments on the lattice location of Er in CZ Si single crystals with a well-defined O concentration of 6.5–6.6×1017cm−3 and 60keV-implanted Tm+Er doses ranging from 4.3×1012 to 3.6×1013cm−2. The experimental results are compared with the predictions of a simulator which models the formation of ErnOm clusters on the basis of simple diffusion and capture kinetics. We find that our experimental data compare favorably with a scenario where the formation of ErnOm defects with one or more O atoms is responsible for removing the Er atoms from their tetrahedral interstitial (T) sites. This suggests that Er does no longer occupy the T site even in simple (ErO) pairs.

Structure Changes in Cz-Si Single Crystals Irradiated with Fast Oxygen and Neon Ions

The research of the surface and the near-surface region of Cz-Si wafers irradiated with fast oxygen and neon ions of energy 4 MeV/u and dose 10 14 particles/cm 2 is presented. In our study several methods based on the Bragg case of X-ray diffraction using Ag K« 1 , as well as reflection high-energy electron diffraction and Nomarsky optical microscopy were used. It was • shown that implantation with fast neon ions causes larger disturbances of silicon crystal structure than irradiation with oxygen ions.

Effects of pulling rate fluctuation on the interstitial-vacancy boundary formation in CZ-Si single crystal

In CZ-Si crystal, the position of interstitial-vacancy (i-v) boundary is mainly controlled by the factors of crystal pulling rate and temperature gradient. However, the fluctuations of both high and low frequencies in pulling rate did not vary the i-v boundary position severely. The reason for this was found to be the time-delayed phenomena in crystal growth process. The radial variation of i-v boundary based on the V/G was derived from the modeling of the time-delayed growth characteristics.

Lattice Sites and Damage Annealing of Implanted Tm and Er IN Si

ABSTRACTWe have studied the lattice sites of Er in CZ Si single crystals by using conversion electron emission channeling from the isotope 167mEr (2.27 s) which is the decay product of radioactive Tm 167m(9.25 d). Following 60 keV implantation of 167Tm at a dose of 4×1013 cm−2 and annealing at 600°C, more than 90% of 167mEr is found close to tetrahedral insterstitial(T) sites. The tetra-hedral fraction of 167mEr decreases considerably after 10min annealing at 800°C and above. We attribute this to the onset of diffusion of the parent 167Tm and its trapping at other defects, presumably oxygen atoms or clusters of Tm/Er.

Hydrostatic Pressure Effect on Oxygen Precipitates in Silicon Single Crystal

Czochralski-grown Si single crystals (Cz-Si) subjected to hydrostatic pressure (HP) can change defect stucture and so the bulk properties influenced by defects. This effect is related mostly to the oxygen-induced defects existing in the bulk of annealed samples [1-4], e.g. oxygen precipitates (OP) composed of SiO2 [3]. In this paper we investigate the effect of HP on the defect structure of Cz-Si monocrystals containing OP. The isostatic and pulsating HP as well as ultrasound (US) treatments at room temperature were applied. Also the high pressure-high temperature (HP-HT) treatment was used to modify the elastic misfit e at the OP/Si boundary [3]. The OP density dop in the preliminary annealed Cz-Si single crystals (oxygen concentration cO up to 10 18 cm-3) was in the range of (10 5-107) cm-2 . The samples were subjected to the HP treatment up to 1.8 GPa, to the HP-HT treatment at HT up to 1620 K or to the HP-US treament at HP up to 1 GPa (the US amplitude up to 9 MPa, frequency 17 kHZ) [5]. The HP induced changes of

ＶＬＳＩと結晶

Correlation between VLSI and crystal technology is comprehensively reviewed for crystallogra-phers who are not necessarily familiar to semiconductor devices. Questions such as “Why are VLSI devices produced by high-quality CZ Si single crystals?”and“Why is an epitaaial wafer necessary for VLSI?”are answered. Importance of wafer flatness in the fabrication of VLSI devices, and microdefects in CZ Si and their application to intrinsic gettering are also included. Moreover, it is emphasized that advanced techniques of material characterization, which will be indispensable to VLSI in the near future, are earnestly desired in the VLSI field. [J. Cryst. Soc. Jpn. 28, 72 (1986) ] .