Study of fluorine behavior in silicon by selective point defect injection

Kham, M.N.; Mubarek, H.A.W. El; Bonar, J. M.; Ashburn, P.

doi:10.1063/1.1984094

Cited by 8 publications

(5 citation statements)

References 15 publications

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“…The shallow fluorine peak is located in the vacancy-rich region of the fluorine implant damage profile and this leads us to conclude that it is due to fluorine trapped in vacancy-fluorine clusters [12]. This conclusion has been confirmed by point defect injection studies on fluorine implanted samples [21]. The reduction of boron thermal diffusion above the critical fluorine dose is then explained by the action of the vacancy-fluorine clusters in suppressing the interstitial concentration in the silicongermanium layer.…”

Section: Boron Diffusion Control Using Fluorinementioning

confidence: 64%

Properties and benefits of fluorine in silicon and silicon-germanium devices

Ashbur,

A. W. El Mubarek

2007

JTIT

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This paper reviews the behaviour of fluorine in silicon and silicon-germanium devices. Fluorine is shown to have many beneficial effects in polysilicon emitter bipolar transistors, including higher values of gain, lower emitter resistance, lower 1/f noise and more ideal base characteristics. These results are explained by passivation of trapping states at the polysilicon/silicon interface and accelerated break-up of the interfacial oxide layer. Fluorine is also shown to be extremely effective at suppressing the diffusion of boron, completely suppressing boron transient enhanced diffusion and significantly reducing boron thermal diffusion. The boron thermal diffusion suppression correlates with the appearance of a fluorine peak on the SIMS profile at approximately half the projected range of the fluorine implant, which is attributed to vacancy- fluorine clusters. When applied to bipolar technology, fluorine implantation leads to a record fT of 110 GHz in a silicon bipolar transistor.

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Section: Boron Diffusion Control Using Fluorinementioning

confidence: 64%

Properties and benefits of fluorine in silicon and silicon-germanium devices

Ashbur,

A. W. El Mubarek

2007

JTIT

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“…The formation of F complexes with V´s or I´s is considered to be responsible for F retention. The shallow peak of F in the plot may be related to F-V complexes formation, since this region is known to be rich in V´s [16,17]. Si I´s are predominant around Rp and beyond.…”

Section: Resultsmentioning

confidence: 99%

“…Our model also includes the formation of immobile F-V and F-I complexes, whose energies are based on those of V´s and I´s clusters and in the case of F-V complexes also based on ab-initio calculations [15]. The observed F accumulation at V´s rich regions can be modeled by F-V complexes [16,17], whereas F-I complexes may account for the experimental reports of F trapping at end of range defects and around Rp [18,19]. In short, a complete F model has been developed, including F i as the diffusing species and the formation of F-I and F-V complexes, reproducing the main features of F behavior.…”

Section: Simulation Modelmentioning

confidence: 99%

Fluorine Profile Distortion upon Annealing by the Presence of a CVD Grown Boron Box

López¹,

Pelaz²,

Duffy³

et al. 2006

AIP Conference Proceedings

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We provide experimental evidence of the distortion of a F profile by the presence of a CVD grown B box. After annealing, a depletion in the F profile is observed fitting the position of the immobile part of B profile. To study this phenomenon further experiments were designed and atomistic simulations were done using a recently developed F model. In this model F complexes with both Si interstitials (F-I) and vacancies (F-V) are included. The formation of Boron-Interstitial Clusters is found to reduce the local Si interstitials defect concentration. This feature may be responsible for the reported F distortion by the presence of a B box.

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“…7,8 The shallow fluorine peak was attributed to vacancy-fluorine ͑V-F͒ clusters 7,8 and point defect injection experiments have since been performed that confirm this interpretation. 13,14 Positron annihilation spectroscopy has also directly confirmed the presence of V-F clusters in fluorine implanted silicon. 15 Recent work on fluorine implantation into preamorphized silicon has also suggested that V-F clusters are responsible for the suppression of boron transient enhanced diffusion.…”

Section: Introductionmentioning

confidence: 91%

“…This method of selective point defect injection has been successfully applied to boron and arsenic diffusions in Si and SiGe, 17,18 and further details can be found in Ref. 13. The wafers were then cut into 1 ϫ 1 cm 2 pieces and annealed at 1000°C for 10-120 s in an oxygen atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Reduced boron diffusion under interstitial injection in fluorine implanted silicon

Kham

Maťko

Chenevier

et al. 2007

Journal of Applied Physics

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Point defect injection studies are performed to investigate how fluorine implantation influences the diffusion of boron marker layers in both the vacancy-rich and interstitial-rich regions of the fluorine damage profile. A 185 keV, 2.3ϫ 10 15 cm −2 F + implant is made into silicon samples containing multiple boron marker layers and rapid thermal annealing is performed at 1000°C for times of 15-120 s. The boron and fluorine profiles are characterized by secondary ion mass spectroscopy and the defect structures by transmission electron microscopy ͑TEM͒. Fluorine implanted samples surprisingly show less boron diffusion under interstitial injection than those under inert anneal. This effect is particularly noticeable for boron marker layers located in the interstitial-rich region of the fluorine damage profile and for short anneal times ͑15 s͒. TEM images show a band of dislocation loops around the range of the fluorine implant and the density of dislocation loops is lower under interstitial injection than under inert anneal. It is proposed that interstitial injection accelerates the evolution of interstitial defects into dislocation loops, thereby giving transient enhanced boron diffusion over a shorter period of time. The effect of the fluorine implant on boron diffusion is found to be the opposite for boron marker layers in the interstitial-rich and vacancy-rich regions of the fluorine damage profile. For marker layers in the interstitial-rich region of the fluorine damage profile, the boron diffusion coefficient decreases with anneal time, as is typically seen for transient enhanced diffusion. The boron diffusion under interstitial injection is enhanced by the fluorine implant at short anneal times but suppressed at longer anneal times. It is proposed that this behavior is due to trapping of interstitials at the dislocation loops introduced by the fluorine implant. For boron marker layers in the vacancy-rich region of the fluorine damage profile, suppression of boron diffusion is seen for short anneals and then increased diffusion after a critical time, which is longer for inert anneal than interstitial injection. This behavior is explained by the annealing of vacancy-fluorine clusters, which anneal quicker under interstitial injection because the injected interstitials annihilate vacancies in the clusters.

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Study of fluorine behavior in silicon by selective point defect injection

Cited by 8 publications

References 15 publications

Properties and benefits of fluorine in silicon and silicon-germanium devices

Properties and benefits of fluorine in silicon and silicon-germanium devices

Fluorine Profile Distortion upon Annealing by the Presence of a CVD Grown Boron Box

Reduced boron diffusion under interstitial injection in fluorine implanted silicon

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