The use of numerical simulation to predict the unlocking stress of dislocations in Cz-silicon wafers

Giannattasio, A.; Senkader, S.; Azam, Sufyan; Falster, R.; Wilshaw, Peter R.

doi:10.1016/s0167-9317(03)00434-9

Cited by 10 publications

(5 citation statements)

References 12 publications

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“…These together with the value for the oxygen binding energy to a dislocation can be used in the numerical model used to solve the diffusion equation to predict the concentration of oxygen atoms at the dislocation core during any series of annealing treatments. 19 This data, together with the temperature dependence of the dislocation unlocking stress, can then be used to predict the stress required to move dislocations in a silicon wafer during device processing. Such predictions are only indicative because in a real wafer dislocations may be produced at precipitates or near the surface where the oxygen concentration is not equal to that in the bulk.…”

Section: G462mentioning

confidence: 99%

Oxygen and Nitrogen Transport in Silicon Investigated by Dislocation Locking Experiments

Giannattasio

Murphy

Senkader

et al. 2005

J. Electrochem. Soc.

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The behavior of oxygen and nitrogen impurities in silicon has been investigated using a novel dislocation locking technique. The locking effect of oxygen in Czochralski silicon ͑CZ-Si͒ was investigated in the 350-850°C temperature range and was found to display five well-defined regimes as a function of annealing time. Results indicate that enhanced transport of oxygen to dislocations takes place for temperatures below ϳ700°C. Numerical simulations of the enhanced oxygen transport indicate that the effective diffusivity becomes dependent on oxygen concentration with an activation energy of approximately 1.5 eV. The same technique has been used to investigate nitrogen transport in nitrogen-doped float-zone silicon in the 550-830°C temperature range and shows nitrogen to have a comparable locking effect to oxygen in CZ-Si, despite being present in a concentration that is 2 orders of magnitude lower. The stress required to unlock dislocations at 550°C which have previously been immobilized by nitrogen during an annealing step, initially increases approximately linearly with the duration of the anneal before saturating to a steady-state value of approximately 50 MPa for all anneal temperatures investigated. An expression for the transport of nitrogen to the dislocations was deduced, which has an activation energy of 1.45 eV.Oxygen is the major nonelectrically active impurity in Czochralski silicon ͑CZ-Si͒ and is normally present in concentrations of 10 17 -10 18 cm −3 . The presence of oxygen has both beneficial and detrimental influences on the production of integrated circuits using CZ-Si wafers. At the temperatures used for device processing, the oxygen is supersaturated and tends to form precipitates. These precipitates and any associated dislocations and stacking faults are often advantageous, because they act as gettering centers for unwanted metallic impurities. However, for gettering to work effectively the concentration and distribution of precipitates throughout the wafer must be carefully controlled. This in turn requires that the nucleation and growth of the precipitates is also controlled and these processes depend upon the transport of the oxygen through the wafer. Moreover, because the nucleation processes often take place in the 450-650°C temperature range, it is important to have accurate data on oxygen diffusion at these temperatures, and until recently, this has largely been lacking.The presence of oxygen is also beneficial in that any left in solution is found to strengthen wafers and reduce the incidence of warpage. 1 However, oxygen also has negative effects, such as the production of mobile dislocations which are sometimes induced by large oxide precipitates. These mobile dislocations can weaken wafers and lead to warpage. Their immobilization or retardation can be achieved by the diffusion of oxygen atoms to the dislocation core, effectively resulting in the locking of dislocations. 2-4 Once again, this process depends on the transport of oxygen through the crystal and also on subsequent oxyge...

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Section: G462mentioning

confidence: 99%

Oxygen and Nitrogen Transport in Silicon Investigated by Dislocation Locking Experiments

Giannattasio

Murphy

Senkader

et al. 2005

J. Electrochem. Soc.

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“…Effect of interstitial oxygen atoms on critical shear stress.-It is well known that oxygen atoms affect critical shear stress through locking effect. 5,10,19,20,[28][29][30][31][32] The locking stress can be expressed by the following;…”

Section: Discussionmentioning

confidence: 99%

Effect of Surface Oxygen Concentration on Wafer Strength in Floating Zone Si Wafers

Fujise

Ono

et al. 2020

ECS J. Solid State Sci. Technol.

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The critical stress behavior of low-oxygen-concentration silicon wafers was elucidated by measuring the critical stress of slip generated owing to scratches using the high-temperature three-point bending test method. It is well known that floating zone (FZ) wafers with low oxygen concentrations tend to easily cause slips from dislocation sources such as scratches. The first point observed in the study is that the critical shear stress of FZ wafers had no temperature dependence above 973 K, which may suggest the presence of long-range obstacles for dislocation motion. The second point is that slip generation from scratches was less likely to occur when oxygen atoms were inwardly diffused into the wafer surface by high-temperature thermal treatment. These results will contribute to solving the problem of slip generation from backside scratches, often created during the insulated gate bipolar transistor manufacturing process in which FZ wafers are used.

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“…The setting of the holding time after the temperature rise is related to the force, which hinders the movement of the dislocation by the fixation of oxygen to the dislocation (locking force); note that the locking force greatly affects the critical stress. 12,15) It has been reported that the time for the locking force to saturate at the lowest temperature of 700 °C in this test is about 1 h. 12) Therefore, in this test, the holding time was set to 1.5 h. Since the yield stress generally depends on the strain rate in the bending test, it is necessary to set a specific strain rate. The strain rate at the surface was 5.3 × 10 −6 s −1 when the rod lowering speed was 0.1 mm=min, and the test was conducted under this condition.…”

Section: Stress Applicationmentioning

confidence: 99%

Measurement and empirical equation of critical stresses for slip generation from oxide precipitates in silicon wafers

Fujise

Ono

et al. 2018

Jpn. J. Appl. Phys.

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The behavior of slip dislocations generated from oxide precipitates or bulk microdefects (BMDs) in Czochralski silicon wafers with different BMD sizes and oxygen concentrations has been studied using three-point bending tests at high temperatures (700-850 °C). We have developed a method of measuring critical stresses for slip generation caused by BMD growth. It has been found that not only the locking effect of residual oxygen on dislocations but also other factors such as BMD size are important for critical stress to generate and mobilize slip dislocations on {111} crystallographic planes, especially in high temperature ranges. An empirical equation for the estimation of the critical stress has also been produced using a simple model and the experimental results obtained in this study. The formulation enables us to accurately estimate the behavior of slip deformation under various thermal stress conditions.

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The use of numerical simulation to predict the unlocking stress of dislocations in Cz-silicon wafers

Cited by 10 publications

References 12 publications

Oxygen and Nitrogen Transport in Silicon Investigated by Dislocation Locking Experiments

Oxygen and Nitrogen Transport in Silicon Investigated by Dislocation Locking Experiments

Effect of Surface Oxygen Concentration on Wafer Strength in Floating Zone Si Wafers

Measurement and empirical equation of critical stresses for slip generation from oxide precipitates in silicon wafers

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