Comparison of the Impact of Thermal Treatments on the Second and on the Millisecond Scales on the Precipitation of Interstitial Oxygen

Kissinger, G.; Kot, Dawid; Ammon, Wilfried von

doi:10.1149/2.008206jss

Cited by 11 publications

(12 citation statements)

References 13 publications

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“…Therefore, BMD formation is suppressed in wafers after flash lamp annealing for 20 ms. 9 All simulations shown here were made for 900 μm thick squared silicon wafers with 70 mm side length which represents the geometry of the sawed wafers. The displacement of such a wafer as the result of the thermal gradients during a 20 ms flash is shown in Fig.…”

Section: Results Of Modeling and Discussion Of Experimental Resultsmentioning

confidence: 99%

“…The reason is that the formation of dislocations would require overcoming the energy barrier of homogeneous nucleation of dislocations which is too high and would need stresses in the GPa range. Oxygen precipitates as sources for nucleation of dislocations can be excluded as well in our experiments because the grown-in oxygen precipitates are too small and just shrink during FLA. 9 …”

Section: Results Of Modeling and Discussion Of Experimental Resultsmentioning

confidence: 99%

“…They can lead to different stages of shrinking of the grown-in oxygen precipitate nuclei depending on the temperature reached and they can influence the profiles of the concentration of intrinsic point defects. 9 Fig. 4 shows the temperature profile during the flash (full lines) and during cooling (dashed lines) for the flash duration used.…”

Section: Results Of Modeling and Discussion Of Experimental Resultsmentioning

confidence: 99%

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Dislocation Generation and Propagation during Flash Lamp Annealing

Kissinger

Kot

Schubert

et al. 2015

ECS J. Solid State Sci. Technol.

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Dislocation generation and propagation during flash lamp annealing for 20 ms was investigated using wafers with sawed, ground, and etched surfaces. Due to the thermal stress resulting from the temperature profiles generated by the flash pre-existing dislocations propagate into the wafer from both surfaces during flash lamp annealing. A dislocation free zone was observed around 700 μm depth below the surface of a 900 μm thick sawed wafer. The dislocation propagation can be well described by a three-dimensional mechanical model. It was further demonstrated that in wafers being initially free of dislocations no dislocations are generated during flash lamp annealing. © The Author During the last years, thermal processing on the millisecond scale was developed first of all for the creation of shallow dopant profiles in high end electronic device technologies and for the thermal treatment of layers.1,2 Flash lamp anneals (FLA) or laser anneals are able to heat the silicon wafer within a few milliseconds to temperatures up to the melting point. Depending on the irradiance of the flash, this can cause strong thermal gradients in the wafers inducing thermal stress which can generate defects. The aim of our investigations was to investigate dislocation generation and propagation during FLA. In addition, we modeled the temperature distribution and stress in a silicon wafer subjected to FLA and compared it to experimental results of dislocation propagation. The results of modeling help to understand the experimental results. ExperimentalThe experimental flow can be seen in Fig. 1. The wafers used for the experiments were 150 mm in diameter and of a resistivity of about 10 cm. The concentration of interstitial oxygen was in the range of 6.9-7.1 × 10 17 cm −3 (DIN 50438/1, new ASTM F121-83). In order to investigate dislocation generation and propagation during FLA, wafers of different surface state were prepared. Part of the wafers, 900 μm in thickness, was just sawed, another part was also ground down to a thickness of 750 μm, and the remaining part was also etched after grinding down to a thickness of 680 μm. After subjecting these wafers to FLA for 20 ms in nitrogen, (110) cleavage planes perpendicular to the surface were etched by Secco etchant for 3 min for dislocation delineation. The FLAs were carried out for 20 ms with a normalized irradiance of 0.97 using the flash annealing tool of the Institute for Ion Beam Physics and Materials Research of the HZDR. A tool for flash annealing usually contains both, halogen lamps for pre-heating and xenon lamps for the flash. Descriptions of typical tools for flash lamp annealing can be found in Refs. 1 and 2. In our case, the wafer was pre-heated for about 2 min from the back side by halogen lamps up to a temperature of 800• C. This helps to reduce the thermal gradients, the wafer stress, and reduces the energy required by the flash to reach a certain temperature. Then, the flash was initiated by the xenon-lamps energized by discharging a capacitor unit. The wafer was placed betwe...

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Section: Results Of Modeling and Discussion Of Experimental Resultsmentioning

confidence: 99%

Section: Results Of Modeling and Discussion Of Experimental Resultsmentioning

confidence: 99%

Section: Results Of Modeling and Discussion Of Experimental Resultsmentioning

confidence: 99%

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Dislocation Generation and Propagation during Flash Lamp Annealing

Kissinger

Kot

Schubert

et al. 2015

ECS J. Solid State Sci. Technol.

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“…Flash lamp annealing is a method developed a few years ago for the creation of ultra-shallow junctions in high end electronic devices by extremely short anneals in the millisecond range [7]. Flash lamp annealing causes a non-uniform temperature distribution in the wafers which prevents the supersaturation of vacancies in contrast to RTA [8].…”

Section: Introductionmentioning

confidence: 99%

The influence of flash lamp annealing on the minority carrier lifetime of Czochralski silicon wafers

Kissinger¹,

Kot²,

Sattler³

2014

AIP Conference Proceedings

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Flash lamp annealing of moderately B-doped CZ silicon wafers for 20 ms with a normalized irradiance of about 0.9 was used to efficiently suppress oxygen precipitation during subsequent thermal processing. In this way, the minority carrier lifetime measured at high injection level by microwave-detected photo-conductance decay (μ-PCD) was increased from about 30 microseconds to about 300 microseconds after a thermal process consisting of 780 °C 3 h + 1000 °C 16 h. The grown-in oxide precipitate nuclei were shrunken to a subcritical size during the flash lamp anneal which prevents further growth during subsequent thermal processing.

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“…BMDs appear as black dots and each micrograph shows the whole wafer thickness (725 µm) from top to bottom. The irradiances given in the figure are normalized with respect to the irradiance required for melting of the surface.Simulations of the concentration profiles of the intrinsic point defects(15) have shown that for the flash anneals, the different diffusivity of the intrinsic point defects causes the interstitials to become the dominating point defect in the main part of the wafer. This further promotes suppression of oxygen precipitation.…”

mentioning

confidence: 99%

(Invited) Oxygen Precipitation and Defect Generation in Cz Silicon during Second and Millisecond Annealing

Kissinger¹,

Kot²,

Schubert³

et al. 2014

ECS Trans.

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The precipitation of oxygen was investigated after rapid thermal annealing pre-treatments for 30 s in the range 1100-1250 °C and after flash lamp annealing for 3 ms and 20 ms with different irradiances up to melting of the wafer surface. It was found that the difference between thermal processing on the second and on the millisecond scales is based on the temperature profiles generated by the different types of processing. These profiles influence the shrinking of grown-in oxide precipitate nuclei and the generation, diffusion, and annihilation of intrinsic point defects. It was further found that pre-existing dislocations propagate into the wafer during flash anneals. The dislocation propagation can be well described by a three-dimensional mechanical model.

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Comparison of the Impact of Thermal Treatments on the Second and on the Millisecond Scales on the Precipitation of Interstitial Oxygen

Cited by 11 publications

References 13 publications

Dislocation Generation and Propagation during Flash Lamp Annealing

Dislocation Generation and Propagation during Flash Lamp Annealing

The influence of flash lamp annealing on the minority carrier lifetime of Czochralski silicon wafers

(Invited) Oxygen Precipitation and Defect Generation in Cz Silicon during Second and Millisecond Annealing

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