Minority Carrier Diffusion Length Improvement in Czochralski Silicon by Aluminum Gettering

Joshi, Subhash M.; GÖsele, Ylrich M.; Tan, T. Y.

doi:10.1557/proc-378-279

Cited by 11 publications

(6 citation statements)

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“…The gettering mechanisms such as intrinsic gettering (IG) process induced by oxygen precipitation have been applied as an integral part in the fabrication of integrated circuits [6]. The extrinsic gettering (EG) mechanisms such as phosphorous diffusion gettering (PDG) [7], aluminum alloy gettering (AAG) [4,7] or a combination of phosphorous and aluminum gettering have shown beneficial effects to improve or restore the bulk quality of silicon substrate [7][8][9]. Due to the slow dissolution of precipitate in the dislocation regions, these regions cannot be improved by the conventional PDG or AAG process step [3,8,9].…”

Section: Introductionmentioning

confidence: 99%

“…The porous silicon has a hydrogen-rich surface, which makes the possibility of a bulk passivation effect during the hightemperature oxidation step and may also help to suppress the electrically active defects in the bulk region of the mc-Si substrate [18,19]. The grain boundary and dislocation passivation by Al indiffusion or indiffusion of atomic hydrogen generated at the Al-Si may also contribute to enhance SR in the longer wavelength range and hence to an apparent improvement of the minority carrier diffusion length in the porous silicon/aluminum co-gettered samples [3,8,18,20].…”

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Porous silicon and aluminum co-gettering experiment in p-type multicrystalline silicon substrate

Vinod

2007

Science and Technology of Advanced Materials

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The lifetimes of non-equilibrium minority carriers, which bound with the diffusion length, are considered as two important parameters of the low-quality multicrystalline silicon (mc-Si) substrate. Its value defines the quality of the initial substrate. It is also subjected to change as a result of many high-temperature operations during the device fabrication. Therefore, it is necessary to incorporate certain processing steps that either improve or preserve the electronic quality of the mc-Si substrate. In this study, a novel porous silicon and aluminum co-gettering experiment has been applied as a beneficial approach to improve the electronic quality of the low-resistivity mc-Si substrates. Porous silicon layers were prepared by anodization of the n + silicon region by a simple electrochemical etching process using an aqueous HF-based electrolyte, which leads to the creation of porous silicon microcavities. Besides making porous silicon and aluminum co-gettered samples, both phosphorous and aluminum alloy-gettered samples and reference samples were made. The gettering-induced lifetime enhancement in the test samples was monitored by measuring the lifetime/diffusion length of the test samples using two independent methods such as photoconductivity decay (PCD) measurement and the photocurrent generation method (PCM), respectively. The result in both the measurements has shown a reasonably good agreement with each other. Therefore, it is inferred that the applied co-gettering experiment has a synergetic effect to improve the lifetime of the mc-Si substrate. r

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Section: Introductionmentioning

confidence: 99%

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Porous silicon and aluminum co-gettering experiment in p-type multicrystalline silicon substrate

Vinod

2007

Science and Technology of Advanced Materials

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“…All of these impurities diffuse rapidly in silicon [19], indicating the impurity diffusion from the initial site to the gettering layer occurs rapidly and would not limit the gettering process for a reasonably long gettering heat treatment. Measurements of metal impurity segregation coefficients for phosphorus and aluminum layers with respect to silicon [17,20], indicate one would expect a decrease of metal impurity concentration in the silicon on the order of lo-' to This suggests the capture step is potent and does not limit the gettering process. The release of the impurities from their initial site is unstudied and may be responsible for the poor gettering of mc-silicon.…”

Section: Introductionmentioning

confidence: 99%

Rate Limiting Mechanism of Transition Metal Gettering in Multicrystalline Silicon

McHugo¹,

Thompson²,

Imaizumi

et al. 1997

MSF

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We have performed studies on multicrystalline silicon used for solar cells in the as-grown state and after a series of processing and gettering steps. The principal goal of this work is to determine the rate limiting step for metal impurity gettering from multicrystalline silicon with an emphasis on the release of impurities from structural defects. Synchrotron-based x-ray fluorescence mapping was used to monitor the release process. Copper and nickel impurities were found to reside primarily at dislocations in the as-grown state of the material. Short annealing treatments rapidly dissolved the impurity agglomerates. Based on these results and modeling of the dissolution process, copper and nickel is in the form of small agglomerates (

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Section: Introductionmentioning

confidence: 99%

The rate-limiting mechanism of transition metal gettering in multicrystalline silicon

McHugo¹,

Thompson

Imaizumi

1997

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Jufy 1997 DISCLAIMER This document was prepared as an account of work sponsored by t h e United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their emplo~rees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or The Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of t h e United States Government or any agency thereof, or The Regents of the

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Minority Carrier Diffusion Length Improvement in Czochralski Silicon by Aluminum Gettering

Cited by 11 publications

References 11 publications

Porous silicon and aluminum co-gettering experiment in p-type multicrystalline silicon substrate

Porous silicon and aluminum co-gettering experiment in p-type multicrystalline silicon substrate

Rate Limiting Mechanism of Transition Metal Gettering in Multicrystalline Silicon

The rate-limiting mechanism of transition metal gettering in multicrystalline silicon

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