Bulk Stacking Faults Research Articles

An investigation of bulk stacking faults in silicon using photocapacitance transient spectroscopy

Two-step heat-treated silicon wafers have been used to determine the electrical activity of bulk stacking faults. DLTS measurements by Forbes and Haddad show a dominant energy level at E c − E t = 0.48 ±0.05 eV due to oxygen-induced stacking faults. These wafers have been processed in two different facilities to minimize the possibility that the results might depend on impurities incorporated during wafer processing. Low-temperature, photocapacitance transient spectroscopy (PCTS) was used to study the optical cross section as a function of incident photon energies, in the 1300 to 3000 nm range. PCTS measurements done on the same samples show a dominant level at E c − E t = 0.48 ± 0.05 eV. These results are in excellent correlation with the DLTS measurements.

Electrical activity of bulk stacking faults in silicon

Two-step heat-treated silicon wafers have been used to determine the electrical activity of bulk stacking faults. These wafers have been processed in two different facilities to minimize the possibility that the results might depend on impurities incorporated during wafer processing. DLTS measurements show a dominant energy level at E c − E t = 0.48 ± 0.05 eV due to oxygen-induced stacking faults. Trap concentrations have been correlated to optically detectable bulk stacking faults when the size of the stacking faults is more than 1 μn. Our results show the size and density of the stacking faults are related to the observed electrical activity of the microdefects.

Monitoring of Internal Gettering during Bipolar Processes

For monitoring the effectiveness of internal gettering during the sequence of technological processes, established investigation techniques have been applied and compared to results obtained by the palladium test and the recently developed iron test. The iron test enables a quantitative determination of the getter efficiency and of the precipitation behavior of as‐received ingot wafers due to DLTS measurements performed after an intentional contamination of the wafers. By this means the influence of various process conditions on the gettering behavior could be determined. It was found that the temperature of proceeding heat‐treatments should not exceed 1130°C to conserve internal getter efficiency during the processing. Internal gettering was found to be mainly due to the presence of bulk stacking faults, and it does not depend on the density of oxygen precipitates.

Dependence of Warpage of Czochralski-Grown Silicon Wafers on Oxygen Concentration and Its Application to MOS Image-Sensor Device

The resistance of precipitation-treated Czochralski-grown silicon wafers to warpage has been investigated using crystals containing oxygen at a concentration of 5.5-12.3×1017 atoms/cm3. The precipitation softening is effectively suppressed if the oxygen concentration is lower than a threshold value of about 8×1017 atoms/cm3. In wafers with oxygen concentrations of 5.5-8×1017 atoms/cm3, oxygen precipitation proceeds slowly, resulting in slow growth of bulk stacking faults and few dislocation sources. In MOS image-sensor devices, the wafers with such oxygen concentrations have few crystal defects within the area of the photodiodes after processing, which cause the fatal failure of white blemishes detected as white scratches on output pictures.

Depth profile of bulk stacking fault radius in Czochralski silicon

The depth profiles of bulk stacking fault radius formed under the annealed specimen surface of Czochralski silicon wafers have been obtained. It is clearly shown that the depth profiles have been well predicted by the theoretical result. The curve fitting gives the diffusion coefficient of the responsible point defects expressed by D=257 exp[−(2.84±0.66)eV/kT] in the temperature range between 1080 and 1270 °C. It is strongly suggested that vacancies, not self-interstitials, dominate the growth of the bulk stacking faults.

Quantitative EBIC Investigations on Bulk Stacking Faults in Silicon

Quantitative EBIC Investigations on Bulk Stacking Faults in Silicon

Effect of Heavy Doping on the Nucleation and Growth of Bulk Stacking Faults in Silicon

ABSTRACTThe effect of heavily doping silicon3with boron (up to 9.0×19/cm3) or antimony and arsenic (up to 1.0×19/cm3) on the nucleation and growth of bulk stacking faults (BSF) was investigated by the use of three-step heat treatment; 700°C-24 hrs., 900 °C 24 hrs., and 1050 °C up to 48 hrs.The length and density of BSF were determined by optical microscopy after a Secco or Schimmel etch of cleaved specimens. From the effect of heavy doping on the density of BSF we imply the nucleation rate is doping level dependant. The effect of the low temperature (700°C) heat treatment time on the relationship between the density and the length of BSF indicates that the growth of BSF may be a supply-limited process. The effect of a high temperature (1300°C) oxygen dispersion treatment was also investigated. The results are analyzed in terms of a vacancy model.

TEM INVESTIGATION OF OXYGEN PRECIPITATES AND INDUCED DEFECTS IN ANNEALED CZ-Si SINGLE CRYSTAL

In this paper, oxygen precipitates and induced defects in annealed dislocation-free CZ-Si with high oxygen content have been investigated by HVEM. The oxygen precipitates are spherical crystobalite at 750-1050℃. In addition to spherical precipitates, there are some square plate-like oxygen precipitates with {001} habit plane. Punching prismatic dislocation loops are emitted from oxygen precipitates along 〈110〉 directions above 950℃.The loops are interstitial loops with Burgers vector α/2〈110〉 and axis 〈110〉.The loops are generated by a square plate-like precipitate or by a cluster of spherical precipitates. When dislocation loop encounters obstacle, the complex dislocation configuration may be produced. A stage in a stacking fault has been observed, it is formed by climb of the stacking fault. If treatment temperature is below 850℃, no bulk stacking fault results.

Surface versus bulk nucleated oxidation-induced stacking faults in silicon wafers

The delineation of oxidation-induced stacking faults in silicon wafers by combined etch pit/optical microscopy techniques has shown that the faults can nucleate due to either surface of bulk sources. However, it is not always possible to unequivocally distinguish between the two types of faults. In addition, it has recently been shown that bulk stacking fault nuclei can be activated by ion implantation prior to oxidation to yield another class of faults. In the present reports, we present representative data on each of these defects, introduce a self-consistent nomenclature, and propose a standardize experimental procedure for the analysis of the variety of etch pit features observed during the processing of silicon device wafers.

Sources of oxidation-induced stacking faults in Czochralski silicon wafers

Using optical microscopy/etch pit techniques for the delineation of defects in {100} Czochralski silicon wafers we have made a one-to-one correlation between bulk stacking faults in oxidized wafers and etch hillocks identified at the same sites before oxidation. Transmission electron microscopy of the hillock defects shows them to be clusters of precipitates ranging in size from 0.01 to 0.3 μm. A discussion of these stacking-fault nucleation sites in light of previous work on ’’swirl’’ defects in float-zone wafers and attempts at preoxidation gettering are also presented along with a model for the formation of the extrinsic stacking faults.

Formation of stacking faults and enhanced diffusion in the oxidation of silicon

The phenomena of the formation of stacking faults and the enhanced diffusion during the oxidation of silicon are shown to be closely related and to have a common cause. A model is presented which at once can consistently explain various aspects of both phenomena; in particular, it is capable of explaining the crystal-orientation dependence of these phenomena and the parabolic growth of stacking faults. The model envisages a small incompleteness (∼ 10−3) of oxidation, producing silicon interstitials. A concept is introduced that these excess interstitials, as they supersaturate the lattice, will undergo surface regrowth. The rate of interface regrowth is proportional to the density of surface kinks, which is in turn dependent on the surface orientation. The dependence is described. Quantitative analyses are given for the excess interstitials, the growth of stacking faults, and the enhancement of diffusion. The analyses also show that the stacking-fault embryos are formed within a very short time of the start of oxidation, usually less than 1 sec, consequently leading to uniform stacking-fault size. The occasionally observed variation in the size of bulk stacking faults is attributed to a continuous formation of stacking-fault nuclei (e.g., oxide clusters and precipitates). The absence of a surface regrowth would predict a 1/4 power law of stacking-fault growth, in contradiction of the experiments.