Effect of Fluorine on the Diffusion of Boron in Amorphous Silicon

Jacques, Jeannette M.; Robertson, L. S.; Jones, K. S.; Bennett, Joe

doi:10.1557/proc-717-c4.6

Cited by 13 publications

(6 citation statements)

References 8 publications

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“…However, there have also been contradictory reports in the literature, which showed that fluorine implants had little or no effect on boron diffusion 12 and even enhanced boron diffusion in amorphous silicon. 13 While there has been considerable research on the effect of fluorine on TEBD, little has been published on the effects of fluorine on the thermal diffusion of boron. In this letter, a study is made of the effect of fluorine on the diffusion of boron in buried marker layers.…”

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confidence: 99%

Reduction of boron thermal diffusion in silicon by high energy fluorine implantation

Mubarek

Ashburn

2003

Applied Physics Letters

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This letter investigates the effect of a deep F ϩ implant on the diffusion of boron in silicon. The effects on boron thermal diffusion and transient enhanced diffusion are separately studied by characterizing the diffusion of a buried boron marker layer in wafers with and without a 185 keV, 2.3 ϫ10 15 cm Ϫ2 F ϩ implant, and with and without a 288 keV, 6 ϫ10 13 cm Ϫ2 P ϩ implant. In samples given both P ϩ and F ϩ implants, the fluorine completely eliminates the transient, enhanced boron diffusion caused by the P ϩ implant, and in samples implanted with F ϩ only, the fluorine suppresses the boron thermal diffusion by 65%. These results are explained by the effect of the fluorine on the vacancy concentration in the vicinity of the boron profile.

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confidence: 99%

Reduction of boron thermal diffusion in silicon by high energy fluorine implantation

Mubarek

Ashburn

2003

Applied Physics Letters

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“…[4][5] However, when samples are preamorphized with germanium, dissimilar results are obtained under the same dopant implantation and annealing processes. [4][5] However, when samples are preamorphized with germanium, dissimilar results are obtained under the same dopant implantation and annealing processes.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Boron Diffusion in Amorphous Silicon

et al. 2004

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In prior works, we demonstrated the phenomenon of fluorine-enhanced boron diffusion within self-amorphized silicon. Present studies address the process dependencies of low temperature boron motion within ion implanted materials utilizing a germanium amorphization. Silicon wafers were preamorphized with either 60 keV or 80 keV Ge + at a dose of 1x10 15 atoms/cm 2 . Subsequent 500 eV, 1x10 15 atoms/cm 2 11 B + implants, as well as 6 keV F + implants with doses ranging from 1x10 14 atoms/cm 2 to 5x10 15 atoms/cm 2 were also done. Furnace anneals were conducted at 550 o C for 10 minutes under an inert N 2 ambient. Secondary Ion Mass Spectroscopy (SIMS) was utilized to characterize the occurrence of boron diffusion within amorphous silicon at room temperature, as well as during the Solid Phase Epitaxial Regrowth (SPER) process. Amorphous layer depths were verified through Cross-Sectional Transmission Electron Microscopy (XTEM) and Variable Angle Spectroscopic Ellipsometry (VASE). Boron motion within as-implanted samples is observed at fluorine concentrations greater than 1x10 20 atoms/cm 3 . The magnitude of the boron motion scales with increasing fluorine dose and concentration. During the initial stages of SPER, boron was observed to diffuse irrespective of the co-implanted fluorine dose. Fluorine enhanced diffusion at room temperature does not appear to follow the same process as the enhanced diffusion observed during the regrowth process.

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] This research has been motivated by the requirement in advanced CMOS technologies to minimize boron diffusion for the formation of shallow source/drain junctions and sharply defined halo profiles. 19,20 The minimization of boron diffusion is also important in bipolar transistors, where boron diffusion limits the achievable base width and hence the value of cutoff frequency that can be obtained.…”

Section: Introductionmentioning

confidence: 99%

“…2 However, there have also been contradictory reports in the literature, which showed that fluorine implants had little or no effect on boron transient enhanced diffusion 10 and that fluorine enhanced boron diffusion in preamorphized silicon 6 using a silicon implant. 15 Recently El Mubarek and Ashburn 18 showed that a deep F + implant significantly reduced boron thermal diffusion, as well as eliminating transient enhanced diffusion.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] A chemical interaction between boron and fluorine has been proposed to explain the suppression of boron transient enhanced diffusion by fluorine, 4,9,11,14,16 in which the fluorine combines with interstitial boron reducing its mobility 4,11,14,16 or reduces the probability of formation of a boron interstitial pair. 9,11 Alternatively, the formation of vacancy-fluorine complexes has been proposed, 13,17,18,[23][24][25][26] which act as a barrier for boron diffusion, 13 or suppress the interstitial concentration and hence reduce boron transient enhanced diffusion 17 and thermal diffusion.…”

Section: Introductionmentioning

confidence: 99%

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Effect of fluorine implantation dose on boron thermal diffusion in silicon

Mubarek

Bonar

Dilliway

et al. 2004

Journal of Applied Physics

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This paper investigates how the thermal diffusion of boron in silicon is influenced by a high energy fluorine implant with a dose in the range 5 ϫ 10 14 -2.3ϫ 10 15 cm −2 . Secondary Ion Mass Spectroscopy (SIMS) profiles of boron marker layers are presented for different fluorine doses and compared with fluorine profiles to establish the conditions under which thermal boron diffusion is suppressed. The (SIMS) profiles show significantly reduced boron thermal diffusion above a critical F + dose of 0.9-1.4ϫ 10 15 cm −2 . Fitting of the measured boron profiles gives suppressions of the boron thermal diffusion coefficient by factors of 1.9 and 3.7 for F + implantation doses of 1.4 ϫ 10 15 and 2.3ϫ 10 15 cm −2 , respectively. The suppression of boron thermal diffusion above the critical fluorine dose correlates with the appearance of a shallow fluorine peak on the (SIMS) profile in the vicinity of the boron marker layer. This shallow fluorine peak is present in samples with and without boron marker layers, and hence it is not due to a chemical interaction between the boron and the fluorine. Analysis of the (SIMS) profiles and cross-section Transmission Electron Microscope micrographs suggests that it is due to the trapping of fluorine at vacancy-fluorine clusters, and that the suppression of the boron thermal diffusion is due to the effect of the clusters in suppressing the interstitial concentration in the vicinity of the boron profile.

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Effect of Fluorine on the Diffusion of Boron in Amorphous Silicon

Cited by 13 publications

References 8 publications

Reduction of boron thermal diffusion in silicon by high energy fluorine implantation

Reduction of boron thermal diffusion in silicon by high energy fluorine implantation

Enhanced Boron Diffusion in Amorphous Silicon

Effect of fluorine implantation dose on boron thermal diffusion in silicon

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