| 1. |
- Monakhov, E., et al.
(author)
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Boron-enhanced diffusion in excimer laser annealed Si
- 2004
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In: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 114-15, s. 114-117
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Journal article (peer-reviewed)abstract
- The effect of excimer laser annealing (ELA) and rapid thermal annealing (RTA) on B redistribution in B-implanted Si has been studied by secondary ion mass spectrometry (SIMS) and spreading resistance probe (SRP). B has been implanted with an energy of 1 keV and a dose of 10(16) cm(-2) forming a distribution with a width of 20-30nm and a peak concentration of similar to5 x 10(21) cm(-3). It has been found that ELA with 10 pulses of the energy density of 850 mJ/cm(2) results in a uniform B distribution over the ELA-molten region with an abrupt profile edge. SRP measurements demonstrate good activation of the implanted B after ELA, with the concentration of the activated fraction (similar to10(21) cm(-3)) exceeding the solid solubility level. RTA (30 s at 1100degreesC) of the as-implanted and ELA-treated samples leads to a diffusion of B with diffusivities exceeding the equilibrium one and the enhancement is similar for both of the samples. It is also found that RTA decreases the activated B in the ELA-treated sample to the solid solubility limit (2 x 10(20) cm(-3)). The similarity of the B diffusivity for the as-implanted and ELA-treated samples suggests that the enhancement of the B diffusivity is due to the so-called boron-enhanced diffusion (BED). Possible mechanisms of BED are discussed.
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| 2. |
- Monakhov, E. V., et al.
(author)
-
Boron distribution in silicon after excimer laser annealing with multiple pulses
- 2005
-
In: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 124, s. 228-231
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Journal article (peer-reviewed)abstract
- We have studied B re-distribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted using both B and BF2 ions with energies from 1 to 20 keV and doses of 1 x 10(14) and 1 x 10(15) cm(-2). ELA with the number of pulses from 1 to 100 was performed in vacuum with the sample kept at room temperature and 450 degrees C. Independently of the implantation parameters and the ELA conditions used, a peak in the B concentration is observed near the maximum melting depth after 10 pulses of ELA. A detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. An increase in the carrier concentration at the maximum melt depth is observed after ELA with 100 pulses. No structural defects have been detected by transmission electron microscopy in the region of the B accumulation.
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| 3. |
- Monakhov, E. V., et al.
(author)
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Boron distribution in silicon after multiple pulse excimer laser annealing
- 2005
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:8
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Journal article (peer-reviewed)abstract
- We have studied B redistribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted with energies of 1 and 10 keV and doses of 1x10(14) and 1x10(15) cm(-2). ELA with the number of pulses from 1 to 100 was performed at room temperature and 450 degrees C in vacuum. Irrespective of the implantation parameters and the ELA conditions used, a pile-up in the B concentration is observed near the maximum melting depth after ten pulses of ELA. Moreover, a detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. Besides, an increase in the carrier concentration is observed at the maximum melt depth, suggesting electrical activity of the accumulated B. Formation of Si-B complexes and vacancy accumulation during multiple ELA are discussed as possible mechanisms for the B build-up.
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| 4. |
- Monakhov, E. V., et al.
(author)
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Enhanced boron diffusion in excimer laser preannealed Si
- 2005
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:15
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Journal article (peer-reviewed)abstract
- We have investigated boron diffusion during rapid thermal annealing in Si implanted with boron using an energy of 1 keV and a dose of 1 x 10(16) cm(-2). Two types of samples have been studied: As-implanted and pretreated with excimer laser annealing. For both types an enhanced diffusion of boron has been observed with an enhancement by a factor of 3-5 over the standard diffusion. It is suggested that the high concentration of implanted boron is a dominant factor for the diffusion enhancement as compared to the effect of implantation-induced damage. The data indicate that the proximity of the surface can also affect the boron diffusion enhancement.
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| 5. |
- Monakhov, E. V., et al.
(author)
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Excimer laser annealing of B and BF2 implanted Si
- 2005
-
In: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 124, s. 232-234
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Journal article (peer-reviewed)abstract
- We have performed a comparative study of B re-distribution and electrical activation after excimer laser annealing (ELA) of B and BF2 implanted Si. Chemical B concentration and electrical activation profiles were measured by secondary ion mass spectrometry (SIMS) and spreading resistance profiling (SRP), respectively. SIMS data demonstrate that the presence of F does not influence significantly the re-distribution of B during ELA. A dramatic contrast, however, can be observed in the electrical activation of the dopant in the B and BF2 implanted samples. While almost 100% electrical activation of B occurs in the B implanted samples, only 20-50% of the dopant can be activated by ELA in the BF2 implanted sample. Possible mechanisms causing the deactivation of B in the BF2 implanted samples after ELA are discussed.
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| 6. |
- Monakhov, E. V., et al.
(author)
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Excimer laser annealing of shallow As and B doped layers
- 2004
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In: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 114-15, s. 352-357
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Journal article (peer-reviewed)abstract
- Excimer laser annealing (ELA) of As-, B- and BF2-implanted Si has been studied by secondary ion mass spectrometry (SIMS), spreading resistance probe (SRP) and transmission electron microscopy (TEM). The implantations have been performed in the energy range from I to 30 keV with doses of 10(15)-10(16) cm(-2). ELA has been carried out with the energy densities in the range of 600-1200 mJ/cm(2) and the number of laser pulses from 1 to 10. It is shown that ELA results in a more uniform dopant distribution over the doped region with a more abrupt profile edge as compared to those after rapid thermal annealing (RTA). Besides, in contrast to RTA, ELA demonstrates a highly confined annealing effect, where the distribution of dopants below the melting region is not affected. SRP measurements demonstrate almost complete activation of the implanted dopants after ELA, and TEM does not reveal extended defects in the ELA-treated samples. The depth of the doped layers, abruptness of the profiles and the total doping dose as a function of ELA energy density and number of laser pulses are investigated. Computer simulations of ELA show a good agreement with the experimental data.
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| 7. |
- Monakhov, E. V., et al.
(author)
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The effect of excimer laser pretreatment on diffusion and activation of boron implanted in silicon
- 2005
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:19
-
Journal article (peer-reviewed)abstract
- We have investigated the effect of excimer laser annealing (ELA) on transient enhanced diffusion (TED) and activation of boron implanted in Si during subsequent rapid thermal annealing (RTA). It is observed that ELA with partial melting of the implanted region causes reduction of TED in the region that remains solid during ELA, where the diffusion length of boron is reduced by a factor of similar to 4 as compared to the as-implanted sample. This is attributed to several mechanisms such as liquid-state annealing of a fraction of the implantation induced defects, introduction of excess vacancies during ELA, and solid-state annealing of the defects beyond the maximum melting depth by the heat wave propagating into the Si wafer. The ELA pretreatment provides a substantially improved electrical activation of boron during subsequent RTA.
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