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• Two-step annealing enhances oxygen precipitation, and thus reduce the recovery of minority carrier lifetime during phosphorus gettering. • The effectiveness of phosphorus gettering is influenced by the size and quantity of oxygen precipitates. This study investigates the effects of single-step and two-step annealing processes on the formation of oxygen precipitates and their impact on metal impurity gettering in gallium-doped monocrystalline silicon. The research focuses on the competitive relationship between internal gettering by oxygen precipitates and external gettering through phosphorus diffusion. Experimental results show that two-step annealing generates larger and more abundant oxygen precipitates, enhancing the internal gettering effect and reducing the recovery of minority carrier lifetime after phosphorus gettering. Despite this, phosphorus diffusion gettering remains effective in improving minority carrier lifetime, although the degree of improvement depends on the size and quantity of oxygen precipitates. These findings offer valuable insights for optimizing the fabrication process of silicon-based solar cells. [ABSTRACT FROM AUTHOR]

The effects of germanium (Ge)-doping with concentrations in the range of 1018–1020 cm−3 on oxygen precipitation (OP) in Czochralski (CZ) silicon wafers subjected to the low (800 °C)–high (1000 °C) two-step anneal following the rapid thermal anneal (RTA) at 1250 °C, which is actually the RTA-based internal gettering (IG) process, have been comprehensively investigated. It is found that whether the Ge-doping enhances or suppresses OP in the CZ silicon wafers with the aforementioned three-step anneal is quite dependent on the Ge-doping concentration and on the nucleation time at 800 °C. On the one hand, the Ge-doping is experimentally and theoretically revealed to facilitate the formation of vacancy-oxygen (VOm, m ≥ 1) complexes in the CZ silicon wafer during the prior RTA at 1250 °C. In this sense, the Ge-doping enhances the nucleation of oxide precipitates thus being beneficial for OP. On the other hand, the considerably high concentration of Ge-doping introduces compressive stress into silicon lattice in a manner due to the slightly larger covalent radius of Ge atom. Such introduced compressive stress not only increases the critical size required for the onset growth of oxide precipitate nuclei at 1000 °C but also suppresses the growth of oxide precipitates in the course of 1000 °C anneal. Thus, the Ge-doping is unfavorable for the growth of oxide precipitates. Based on the advantageous and disadvantageous effects of Ge-doping on the nucleation and growth of oxide precipitates, respectively, which have been definitely revealed in this work, the above finding has been essentially understood. Of practical significance, this work offers technological guideline to improve the IG capability of CZ silicon wafer through adopting appropriate Ge-doping and RTA-based annealing scheme. [ABSTRACT FROM AUTHOR]

The behavior of oxide precipitates during solar cell fabrication processes and the resulting effect on device performance have been investigated by transmission electron microscopy (TEM) observation. Samples were prepared with different carbon concentration and under different crystal growth conditions, namely using the conventional and an advanced process. The density of oxide precipitates increased monotonically with the carbon concentration, while the cell efficiency improved with decreasing oxygen precipitate density. When the carbon concentration was reduced to below 1016 cm−3, the oxide precipitates grew largely and dislocations were introduced. TEM observations confirmed that the morphology of the oxide precipitates clearly differed depending on the crystal growth conditions. Precipitates grown in platelet form introduced high density dislocations in their surroundings, while the dislocation density was relatively lower around polyhedral-type precipitates. These results thus reveal that oxygen precipitation can be controlled by varying the crystal growth conditions, possibly contributing to the production of high-efficiency solar cells. [ABSTRACT FROM AUTHOR]

This article presents experimental and simulation studies on the formation of recombination‐active ring‐like defects during thermal donor (TD) formation at 450 °C in n‐type Czochralski‐grown silicon wafers. With increasing anneal duration from 1 to 24 h, the resistivity and interstitial oxygen concentration of samples decrease, consistent with the formation of TDs. However, after a subsequent TD annihilation treatment, the resistivity recovers completely, while the interstitial oxygen concentration recovers only partially. Furthermore, the wafers exhibit ring‐like defects in photoluminescence images after the TD generation and remain persistent even after annihilation treatment. By applying a tabula rasa (TR) treatment prior to TD generation anneals, the net loss of interstitial oxygen is reduced, and the incubation time of the ring‐like defects is extended in comparison to as‐grown wafers. Finally, to investigate the possibility of low‐temperature precipitation, simulation of oxygen precipitation (OP) kinetics during the 450 °C annealing steps is performed using an enhanced effective diffusivity of oxygen. These simulations demonstrate that OP can occur simultaneously during TD formation, resulting in recombination‐active ring‐like defects. [ABSTRACT FROM AUTHOR]

High‐temperature annealing, known as Tabula Rasa (TR), proves to be an effective method for dissolving oxygen precipitate nuclei in n‐Cz silicon and makes this material resistant to temperature‐induced and process‐induced lifetime degradation. Tabula Rasa is especially effective in n‐Cz wafers with oxygen concentration >15 ppma. Vacancies, self‐interstitials, and their aggregates result from TR as a metastable side effect. Temperature‐dependent lifetime spectroscopy reveals that these metastable defects have shallow energy levels ~0.12 eV. Their concentrations strongly depend on the ambient gases during TR because of an offset of the thermal equilibrium between vacancies and self‐interstitials. However, these metastable defects anneal out at typical cell processing temperatures ≥850°C and have little effect on the bulk lifetime of the processed cell structures. Without dissolving built‐in oxygen precipitate nuclei, high‐temperature solar cell processing severely degrades the minority carrier lifetimes to below 0.1 millisecond, while TR‐treated n‐Cz wafers after the cell processing steps exhibit carrier lifetimes above 2.2 milliseconds. High‐temperature annealing, known as Tabula Rasa (TR), proves to be an effective method for dissolving oxygen precipitate nuclei in n‐Cz silicon and makes this material resistant to temperature and process‐induced lifetime degradation. Without dissolving grown‐in oxygen precipitate nuclei, high‐temperature solar cell processing sequence severely degrades the minority carrier lifetimes to below 0.1 ms, while TR‐treated n‐Cz wafers after the cell processing steps exhibit carrier lifetimes >2.2 ms. [ABSTRACT FROM AUTHOR]

We studied how rapid thermal annealing (RTA) affects bulk micro-defects (BMDs) and plastic deformation in Si wafers processed at high temperatures. BMDs caused by oxygen precipitation at 1200 °C were investigated in Si wafers as a function of annealing time with and without RTA and pre-annealing. Only the pre-annealed RTA wafer revealed an average BMD size of ~50 nm after annealing at 800 °C for 2 h and subsequently at 1000 °C for 4 h, and such wafers retained BMDs after annealing at 1200 °C for 500 min. The relationship between BMDs and plastic deformation was investigated for Si wafers subjected to RTA at various temperatures. Dislocations were generated and propagated after the simulated CMOS heat treatment as RTA temperature increased because of the low dislocation pinning effect produced by the reduction in residual oxygen while precipitated oxygen concentration increased. Incident angle deviation in the rocking curve indicated a high degree of plastic deformation caused by high RTA temperature after performing a realistic device fabrication process. We propose that a combination of RTA and a pre-annealing process can improve the internal gettering efficiency during high temperature processing, which controls BMDs. This would balance the residual oxygen and preventing plastic deformation. [ABSTRACT FROM AUTHOR]

We determined characteristics of internal gettering of copper in the vertical direction of p-type silicon wafer. Bulk micro-defects (BMDs) caused by oxygen precipitation and the gettering efficiency of Cu along the vertical direction from the surface into the bulk were investigated for Si wafers with and without rapid thermal annealing (RTA) process. Based on scanning infrared microscopy, secondary ion mass spectrometry, and local etching results, the density of BMDs in Si wafers with RTA process was higher than that in Si wafer without RTA process. Depth profile of Cu concentration was strongly related to the BMD density profile in the vertical direction. According to the transmission electron microscopy analysis, Cu impurities were trapped at BMDs through precipitation of copper silicides. It is proposed that the RTA process can improve the internal getterig efficiency of copper in the vertical direction of p-type silicon wafer. [ABSTRACT FROM AUTHOR]

The effects of the vacancy-related defects introduced by neutron irradiation on oxygen precipitation in Czochralski silicon have been elaborately investigated. It is found that the vacancy-related defects significantly enhance the nucleation of oxygen precipitates as well as the growth of the grown-in oxygen precipitates. The Ostwald ripening of oxygen precipitates in neutron-irradiated silicon wafers is observed during a low-high two-step annealing. It is interpreted that the vacancy-related defects facilitate the formation of platelet-like oxygen precipitates, which continue to grow at the expense of small-sized oxygen precipitates during the high temperature annealing process. However, when subjected to the subsequent rapid thermal annealing at higher temperature, the platelet-like oxygen precipitates in the neutron-irradiated silicon exhibit lower stability due to the large surface free energy. [ABSTRACT FROM AUTHOR]

Oxygen precipitation in heavily arsenic doped Czochralski silicon is investigated for a wide dopant concentration range (from 3 × 1018 cm-3 to 4 × 1019 cm-3) and it is compared with that observed in lightly doped silicon having similar initial oxygen concentration. A lower density of oxide precipitates after an anneal of 4 h at 800 °C followed by 16 h at 1000 °C is measured in the case of arsenic doped samples, in comparison to lightly doped ones, when the dopant concentration exceeds 1.6 × 1019 cm-3. In addition, no radial bands (rings) of precipitation are observed in arsenic-doped samples, contrary to lightly doped samples grown at the same V/G (ratio between pull rate V and axial thermal gradient G). These findings are explained by considering the role played by vacancies in the formation of oxygen precipitates and the impact of the arsenic concentration on the total concentration of point defects in silicon. Data obtained by computer simulation of microdefect formation in silicon are also presented in support of this explanation. [ABSTRACT FROM AUTHOR]

We have investigated the impact of germanium (Ge) co-doping on oxygen precipitation (OP) in heavily boron (B)-doped Czochralski (CZ) silicon subjected to low-high two-step anneal without or with the prior high temperature rapid thermal process (RTP). Herein, the Ge concentration is one order of magnitude higher than the B concentration. It is found that the Ge co-doping exhibits the effect of suppression or enhancement on OP in the heavily B-doped CZ silicon without or with the prior RTP. In the case without the prior RTP, the compressive stress introduced by the Ge co-doping compensates the tensile stress arising from the B-doping, which is not beneficial for the growth of oxide precipitates. While, in the case with the prior RTP, the Ge co-doping increases the amount of vacancies introduced by the RTP and, moreover, may enable to generate more heterogeneous nucleation centers of oxide precipitates, thus leading to the enhanced OP in the heavily B-doped CZ silicon. [ABSTRACT FROM AUTHOR]

Four industrial-scale n-type Czochralski silicon crystals were grown with different impurity contents, i.e. metallics, phosphorus and oxygen. Horizontal slices were obtained from the top and middle of the crystals and were characterized in terms of lifetime and both defect and impurity distribution. The slabs characterization was performed both under as-grown conditions and after 2-step oxidation. Solar cells were fabricated from neighboring wafers with n-PASHA process and the overall efficiency determined. The crystal grown under low oxygen incorporation conditions has shown higher average as-grown lifetimes compared to the other crystals. The addition of lower phosphorus concentration to the melt resulted in an improvement of the lifetime of the crystal while the use of low grade feedstock has mainly affected the quality at the middle of the corresponding crystal. However, the major difference between top and middle heights was still the interstitial oxygen concentration for all crystals under investigation. The distribution of the interstitial oxygen concentration has not shown significant fluctuations through the samples radial direction. In addition, significant void fluctuations were found through the slabs radial direction, and demonstrate possible variations in the vacancy incorporation at the solidification interface during crystal growth. After heat treatment, large fluctuations of the lifetime were found through the samples radial direction, and are mainly associated to the local fluctuations of the oxygen precipitate density. However, these variations were suppressed in the crystal of lower oxygen incorporation. Solar cells performance degradation was mainly correlated with oxygen precipitation during their fabrication. It was also demonstrated that their efficiency is largely affected by the formation of detrimental striations of high periodicity. Their formation was thus associated to fluctuations of the vacancy concentration due to transient growth and their interaction with oxygen during crystal cooling. These oxygen nuclei may grow during solar cells processing and become even more detrimental to their performance. [ABSTRACT FROM AUTHOR]

The radial oxygen nucleation and precipitation in Czochralski-grown silicon crystals is observed in real time via the local evolution of the X-ray Bragg intensity. Using a high X-ray energy and a divergent beam setup, it becomes possible to examine the impact of the local as-grown point defect configuration on the formation of bulk micro defects in a crystal of macroscopic dimensions. As a salient feature the transition from vacancy- to interstitial-dominated regions in a 12' crystal can be identified, and its influence on the precipitation kinetics is quantified through effective oxygen diffusion constant. It appears enhanced by up to a factor of six in vacancy-rich regions as compared to crystal volumes which are identified as point-defect free where it agrees well with the literature value. [ABSTRACT FROM AUTHOR]

Oxide precipitate nucleation at 300 °C in low resistivity As or Sb doped Czochralski Si is studied with and without prior rapid thermal processing (RTP). With prior RTP, a subsequent nucleation anneal even at 300 °C, leads to a high oxide precipitate density after a precipitation anneal at 1000 °C. As this is not observed without prior RTP, the effect is assumed to be related to the introduction of vacancies by RTP. As and Sb are deactivated by the formation of As x-V or Sb x-V complexes. The reduction of free carriers causes an increase of resistivity corresponding with a few times 1017 cm−3 deactivated dopant atoms suggesting that about 1017 cm−3 vacancies are frozen-in after RTP. During subsequent annealing at 300 °C, the resistivity recovers to its original value due to the release of vacancies that can facilitate homogeneous oxide precipitate nucleation or can lead to the formation of VO2 and As-V-O or Sb-V-O complexes acting as heterogeneous nucleation centers that can grow further during subsequent anneals. [ABSTRACT FROM AUTHOR]

The time dependent agglomeration of oxygen in silicon at an annealing temperature of 650 °C is followed in-situ via the variation of the thickness-dependent Pendellösung fringes. The measurement of the 400-reflection of a wedge shaped sample with the characteristic tungsten Kα1-line at 59.31 keV allows to observe changes of the static Debye-Waller factor of about 0.001%. Within the model of spherical precipitates and the classical theory of diffusion-driven precipitation we determine from this a diffusion constant 4.7x10-15 cm²/s for oxygen in silicon at 650 °C which appears enhanced by a factor of 2.4 as compared to normal oxygen diffusion. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Abstract: The aim of this contribution was to investigate the impact of nitrogen doping on oxygen precipitation in wafers obtained from ingots optimized with respect to voids by advanced pulling methods. Wafers cut from these ingots contain a central OSF region and an outer perfect vacancy region. The density of grown-in oxide precipitate nuclei in the wafers was distributed radially very inhomogeneous due to the variation of the vacancy supersaturation being proportional to v/G. Two step thermal treatments with a nucleation at 780°C for 3h or an oxygen out-diffusion anneal at 1100°C for 2h both followed by 1000°C for 16h have shown that nitrogen doping of ingots results in a homogeneous BMD density on the whole wafer. A nitrogen concentration of at least 3×1013 cm−3 is required for the nitrogen enhanced oxygen precipitation indicating that diffusive nitrogen in the form of N2 complexes is a prerequisite for the increase of the nucleation rate. Nitrogen is incorporated into the oxide precipitates increasing the density of the precipitating phase and thus reducing strain energy. [Copyright &y& Elsevier]

We investigated the effect of Fe contamination on the electronic properties of dislocation clusters in relation to oxygen precipitation in multicrystalline silicon (mc-Si). Photoluminescence (PL) spectroscopy and mapping were performed at room and liquid-He temperatures on mc-Si wafers before and after Fe contamination. PL spectra consisted of the band-edge emission, the 0.78-eV emission associated with oxygen precipitates, and the dislocation-related D-lines. The Fe contamination increased the electrically active dislocation clusters. Part of these clusters acted as preferential oxygen precipitation sites, and their electronic properties were not further influenced by the Fe contamination. [ABSTRACT FROM AUTHOR]

Abstract: Czochralski silicon (Cz-Si) doped with germanium (Ge) has recently drawn the attentions on the next generation of Cz-Si materials used for ultra large-scale integrated circuits. Oxygen precipitate, which is the most important micro-defect in Ge-doped Cz-Si (GCz-Si), domains the majority properties of bulk silicon. In this presentation, the behaviors of oxygen precipitation in GCz-Si at high temperatures have been studied. It was found that, compared with conventional Cz-Si, the higher-density but smaller-sized oxygen precipitates were formed in GCz-Si at extremely high temperature, which could be ascribed to the enhanced nucleation of oxygen precipitates by the Ge-doping. Meanwhile, compound morphologies of oxygen precipitates consisted of plate-like and polyhedral shapes were found in GCz-Si, which can probably be ascribed to the different levels of vacancy coalesced by the so-called Ge-related complexes in GCz-Si. [Copyright &y& Elsevier]

Abstract: Oxygen precipitation in heavily phosphorus-doped (P-doped) Czochralski (CZ) silicon subjected to single-step annealing at high temperatures in the range of 1050–1150°C has been investigated. It was indicated that in the heavily P-doped CZ silicon there were more grown-in oxygen precipitates, thus promoting the generation of induced defects and accelerating the Ostwald ripening of oxygen precipitates during the high temperature annealing, in comparison with the control lightly P-doped CZ silicon with comparable initial oxygen concentration and thermal history. Moreover, it was found that, during the annealing at 1050°C, oxygen precipitation in the outer region about 2.5cm in width was noticeably retarded with respect to that in the inner region across the heavily P-doped CZ silicon wafer. The mechanism for the enhanced formation of grown-in oxygen precipitates and the retardation of oxygen precipitation at high temperature, as mentioned above, has been tentatively explained. [Copyright &y& Elsevier]

Abstract: Carrier lifetime limitation defects in polycrystalline silicon ribbons have been examined in samples with high oxygen and carbon content. Infrared spectroscopy showed that essentially all supersaturated oxygen impurities precipitated within 1h annealing at over 800°C. Preferential defect etching revealed that a much higher density of oxygen precipitates were generated in dislocation-free grains than in those highly dislocated (105–107 cm−2) ones. Correlated with electron-beam-induced current imaging, we found that oxygen precipitates are the dominant carrier recombination defects in dislocation-free grains, while dislocations are the lifetime killer for highly dislocated grains. It is suggested that eliminating dislocations alone will not improve the carrier lifetime, considering that a higher density of oxygen precipitates formed in the absence of dislocation-related heterogeneous nucleation sites will significantly degrade the carrier lifetime. [Copyright &y& Elsevier]

Abstract: The term thermal history of silicon wafers represents the whole variety of process parameters of crystal growth. The aim of this contribution is an attempt to specify thermal history by one parameter that is directly correlated to the bulk microdefect density. The parameter that reflects thermal history and correlates it with nucleation of oxide precipitates is the concentration of VO2 complexes. The VO2 concentration in silicon wafers is too low to be measured by FTIR but it can be obtained from the loss of interstitial oxygen during a standardized thermal treatment. Based on this, the vacancy concentration frozen during crystal cooling in the ingot can be calculated. RTA treatments above 1150°C create a well defined level of the VO2 concentration in silicon wafers. This means that a well controlled modification of the thermal history is possible. We also investigated the kinetics of reduction of the as-grown excess VO2 concentration during RTA treatments at 950°C and 1050°C and the effectiveness of this attempt to totally delete the thermal history. [Copyright &y& Elsevier]

Abstract: The effect of stress induced by enhanced hydrostatic pressure (HP, up to 1.2GPa) applied at processing at up to 1400K, on the transformation of interstitial oxygen (Oi) in Ge-doped Czochralski silicon (Cz-Si:Ge, c Ge =7×1017 cm−3) was investigated by spectroscopic, X-ray and electrical methods. While the presence of Ge results in reduced generation of thermal donors (TDs) in Cz-Si:Ge annealed under 105 Pa, the same processing under HP at 675–750K produces TDs in a concentration up to about 1015 cm−3. The treatment under HP at 1270–1400K stimulates agglomeration of interstitial oxygen; the HP-dependent generation of different oxygen-containing defects is observed. The effect of HP on transformation of oxygen in Ge-doped Cz-Si is related, among others, to stress-induced activation of germanium to act as a component of nuclei for precipitation of Oi’s. [Copyright &y& Elsevier]

Abstract: Nitrogen is one of the most important elements in Czochralski (CZ) silicon used in ultra-large scale integrity circuits (ULSI). In last decades, nitrogen-doped Czochralski (NCZ) silicon, which has been widely applied in microelectronic industry, has attracted much attention. In this presentation, the behavior of NCZ silicon treated in rapid thermal process (RTP) has been reviewed. The influence of RTP on oxygen precipitation, bulk microdefects, denuded zone and nitrogen and oxygen complexes in NCZ silicon has been investigated. The interaction of nitrogen with oxygen and vacancies in CZ silicon during RTP is also discussed. [Copyright &y& Elsevier]

Abstract: Czochralski silicon (Cz Si) crystals with germanium (Ge) doping are considered to be of potential application for integrated devices. In this presentation, the influence of Ge doping of Cz Si crystals on oxygen precipitate thermal stability has been discussed. Compared with the conventional Cz Si, oxygen precipitates in Ge-doped Cz (GCz) Si was proposed to be poorer stable thermally during high temperature anneals, which is ascribed to the formation of smaller precipitates. Meanwhile, the oxygen precipitation was promoted in GCz Si wafers that received a high temperature pre-anneal treatment, which has been considered to be associated with the assumption of Ge-related complexes by the intended Ge doping. [Copyright &y& Elsevier]

Abstract: The effect of the prior conventional furnace anneal at 1250°C with different cooling rates on oxygen precipitation in Czochralski silicon during the subsequent low–high two-step heat treatment was investigated. In comparison with oxygen precipitation in the as-received sample, that in the samples with the prior 1250°C anneal with fast or slow cooling rate was significantly enhanced. It is believed that the prior 1250°C anneal with fast cooling rate introduced a considerable amount of vacancies, thus enhancing oxygen precipitation in the subsequent anneal; while, that with slow cooling rate substantially removed the silicon interstitials generated during the formation of grow-in oxygen precipitates, thus eliminating the retard effect on oxygen precipitation in the subsequent anneal. [Copyright &y& Elsevier]

Abstract: Oxygen precipitation in Si strongly depends on the undergoing thermal treatment. Between 350 and 450°C thermal donor formation is activated by a 1.4–1.6eV barrier. On the other hand, at , SiO2 cluster formation is limited by the interstitial oxygen migration barrier of . Volumetric arguments imply that the formation of silica precipitates during anneals of oxygen-rich Si crystals, must be accompanied by the ejection of approximately one Si self-interstitial per SiO2 unit that is formed. We report on ab-initio density-functional studies of small oxygen aggregates in Si, to show that the reaction is exothermic for . The large energy barrier required to form an intermediate defect prevents the formation of complexes at temperatures as low as 450°C. Our results imply that thermal donors are not thermodynamically stable clusters, and their formation is driven by kinetics. Infra-red absorption studies can discriminate and defects. We report their local vibrational modes and compare them with the available experimental data. [Copyright &y& Elsevier]

Abstract: Ham''s theory was applied in order to become independent of detection limits for oxide precipitates and to quantify the phenomenon of oxygen loss to invisible BMDs during thermal treatments. The density of detectable bulk micro-defects (BMDs) depends on the size distribution of grown-in nuclei and the ramp rate, temperature, and duration of the thermal treatment applied. There is no correlation to the invisible BMDs. During conventional annealing, the density of the invisible BMDs decreases exponentially with increasing radius of precipitates at a nearly constant loss of interstitial oxygen. Only if the calculated radius exceeds 70nm, a 100% loss of interstitial oxygen to BMDs detectable by scanning infrared microscopy (SIRM) seems to be possible. After RTA processing at 1230°C, a period of 1h at 1000°C would be necessary for the growing oxide precipitates to reach a saturated density detectable by SIRM, but there remains a very high density of invisible BMDs consuming interstitial oxygen. In N-doped silicon, the vast majority of BMDs is detectable by SIRM, cleave and etch, and infrared light scattering tomography after thermal processing. [Copyright &y& Elsevier]

Systematic measurements aimed at quantifying the contribution of precipitates to the infrared absorption of silicon are presented here, carried out on wafers with the same initial interstitial oxygen (Oi) concentration subjected to three-step treatments. To precisely determine the intensity of the precipitate-related bands, the measurements were performed at liquid He temperature. The results demonstrate the possibility of accounting for the contribution of precipitates in the standard quantitative determination of Oi in silicon at room temperature. [Copyright &y& Elsevier]

In this paper, systematic experiments were performed to investigate the oxygen precipitation of Czochralski (CZ) silicon generated under the high pressure (1 GPa) by means of the transmission electron microscopy (TEM). Specimens were firstly treated under the high pressure of 1 GPa at 450 °C for 10 h, 957 °C for 5 h, and 1130 °C for 5 h, respectively. Compared with the specimens treated under the atmosphere, it reveals that in the specimen treated at 450 °C, a new kind of sphere-like oxygen precipitates with the diameter of about 10 nm were observed, in the specimens treated at 957 °C dislocations with oxygen precipitates were found. The experiments also points out that the polyhedron oxygen precipitates with the size of about 50 nm were generated in the specimens treated at 1130 °C. It is suggested that the high pressure can stabilize the oxygen precipitates with small sizes because of the decrease of self-interstitials and the increase of vacancies. [Copyright &y& Elsevier]

The effect of rapid thermal process (RTP) on the oxygen precipitation and on the denuded zone (DZ) formation in nitrogen-doped Czochralski (NCZ) silicon wafers has been investigated. The DZ can be formed at the surface of NCZ wafers subjected to RTP annealing. However, the oxygen precipitation and bulk microdefects in NCZ silicon are changed by RTP preannealing, which is a result of N–N bonds broken during RTP treatment. [Copyright &y& Elsevier]

The effect of oxygen precipitation on flow pattern defects (FPDs) relative to voids in bulk silicon was investigated. FPDs and voids were measured after different annealing time, and with various interstitial oxygen contents and bulk stacking faults (BSFs). It was found that, during annealing, interstitial oxygen in bulk silicon precipitated, however the FPDs density remained constant. The density of BSFs increased with annealing time at 1100 °C. After annealing, the morphology of voids was found to be octahedral with the oxide films inside them, the same as as-grown samples. Therefore, it is concluded that the interstitial silicon atoms released during oxygen precipitation did not enter the voids because of the resistance of the oxide films inside the voids, but condensed into stacking faults. The dissolution of the oxide films is believed to be the principal cause for the annihilation of voids. [Copyright &y& Elsevier]

The behavior of oxygen precipitation in heavily doped silicon was investigated. The experimental results showed that the behavior of oxygen precipitation in heavily doped silicon is not only related to initial oxygen concentration, but also is affected by dopant species. The growth of oxygen precipitation was not affected by dopant type. Dopant species only influenced the nucleation of oxygen precipitation, and the time of precipitate nucleus formation is shorter in P+ samples than in N+ samples. The morphology of oxygen precipitation is independent of dopant type and only depends on the heat-treatment cycles. Considering the hanging bond on the interface of Si–SiOx at precipitates embryo and amending the free energy item, an expression of nucleation critical radius associated with dopant species was derived, and the dependent relationship of oxygen precipitation behavior in heavily doped silicon and dopant species was explained by this model. Moreover, an effective intrinsic gettering cycle with suitable width of denuded zone in heavily Sb-doped silicon samples was obtained in order to reduce or eliminate the metallic impurities and unwanted defects in the surface of substrate and device active regions. [Copyright &y& Elsevier]

The behavior of the ring-like distribution of oxidation-induced stacking faults (OSFs) in nitrogen-doped Czochralski grown single silicon crystals was investigated as a function of the nitrogen and oxygen content. It was found that the inner and outer boundary of the OSF ring is shifted towards the crystal center with higher nitrogen concentration, while, at the same time, the width of the OSF ring increases. This result can be explained by a qualitative model which takes into account the nitrogen-induced change in the temperature-dependent variation of the vacancy concentration. Without nitrogen doping the OSF ring disappears if the oxygen content drops below a critical value. However, the OSF ring reappears at a sufficient nitrogen doping level. The lower the oxygen content, the higher the nitrogen concentration must be to observe an OSF ring. It is shown that this can be understood using the same qualitative model if a critical width of the OSF ring is introduced below which the OSF ring is no longer detectable. [Copyright &y& Elsevier]

The influence of external high pressure (1 GPa) on oxygen precipitation in Czochralski (Cz) silicon annealed at 450°C has been investigated by means of transmission electron microscopy. It is found that low-temperature annealing under high-pressure results in the tiny sphere-like oxygen precipitates, which can be ascribed to the factors of lower self-interstitial concentration, higher vacancy concentration, and lower diffusivity of interstitial oxygen in silicon crystal exerted by the high pressure. The formation of sphere-like precipitate, which is favorable for minimizing the contribution of interfacial energy to the total precipitate free energy, is probably due to the fact that the annealing for 10 h is still in the early stage of oxygen precipitation. [Copyright &y& Elsevier]

It is shown by energy- and time-resolved phonon spectroscopy with superconducting tunnelling junctions that acoustic phonon scattering depends on the size of oxygen precipitates in the annealed Czochralski silicon crystals. After thermal treatments around 1050°C we find a series of rather narrow scattering resonances that shift under stress. They are possibly due to electronic excitations of acceptor-like states related to oxygen aggregation. [Copyright &y& Elsevier]