Nonmelt laser annealing of 5-KeV and 1-KeV boron-implanted silicon

Earles, Susan K.; Law, Mark E.; Brindos, R.; Jones, K. S.; Talwar, S.; Corcoran, Sean

doi:10.1109/ted.2002.1013265

Cited by 37 publications

(21 citation statements)

References 12 publications

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“…In contrast, the much shorter duration time of excimer laser annealing (<200 ns) is comparable to that of some basic point-defect related phenomena, such as Si interstitial diffusion and clustering 11 , which makes the defect-formation mechanism itself questionable in this annealing regime. In addition, most of the existing studies of defect formation in laser annealed silicon have been carried out in preamorphised structures: (i) after non-melt anneals, conventional endof-range defects ({311} defects and {111} DLs) have been observed [12][13][14] ; (ii) in the case of melt laser annealing, the defects nature depends on the position of the melt front with respect to the amorphous/crystalline, a/c, interface (stacking faults are observed in the case of incomplete melting of the preamorphised layer, 15 defect-free crystalline silicon is found when melting goes beyond the a/c interface 16 ).…”

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confidence: 99%

Extended Defects Formation in Nanosecond Laser-Annealed Ion Implanted Silicon

Qiu

Cristiano

Huet³

et al. 2014

Nano Lett.

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Damage evolution and dopant distribution during nanosecond laser thermal annealing of ion implanted silicon have been investigated by means of transmission electron microscopy, secondary ion mass spectrometry, and atom probe tomography. Different melting front positions were realized and studied: nonmelt, partial melt, and full melt with respect to the as-implanted dopant profile. In both boron and silicon implanted silicon samples, the most stable form among the observed defects is that of dislocation loops lying close to (001) and with Burgers vector parallel to the [001] direction, instead of conventional {111} dislocation loops or {311} rod-like defects, which are known to be more energetically favorable and are typically observed in ion implanted silicon. The observed results are explained in terms of a possible modification of the defect formation energy induced by the compressive stress developed in the nonmelted regions during laser annealing.

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confidence: 99%

Extended Defects Formation in Nanosecond Laser-Annealed Ion Implanted Silicon

Qiu

Cristiano

Huet³

et al. 2014

Nano Lett.

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“…1 Among the other processes nonmelt laser annealing has gained attention as a means of achieving these requirements by its short process time and high annealing temperature, and hence low thermal budget, resulting in high dopant solubility. [2][3][4][5] A problem exists with creating highly active profiles when boron is implanted in conjunction with a preamorphizing germanium implant; deactivation occurs during postactivation thermal processes. [6][7][8][9][10][11][12] This deactivation is thought to be driven by the release of silicon interstitials from end-of-range ͑EOR͒ defects that evolve through nonconservative Ostwald ripening during annealing.…”

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Deactivation of ultrashallow boron implants in preamorphized silicon after nonmelt laser annealing with multiple scans

Sharp

Cowern

Webb

et al. 2006

Applied Physics Letters

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Electrical activation and redistribution of 500 eV boron implants in preamorphized silicon after nonmelt laser annealing at 1150°C and isochronal rapid thermal postannealing are reported. Under the thermal conditions used for a nonmelt laser at 1150°C, a substantial residue of end-of-range defects remained after one laser scan but these were mainly dissolved within ten scans. The authors find dramatic boron deactivation and transient enhanced diffusion after postannealing the one-scan samples, but very little in the five-and ten-scan samples. The results show that end-of-range defect removal during nonmelt laser annealing is an achievable method for the stabilization of highly activated boron profiles in preamorphized silicon. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2385215͔The continued downscaling of complementary metaloxide-semiconductor devices requires ultrashallow and abrupt source/drain extension regions with a low sheet resistance.1 Among the other processes nonmelt laser annealing has gained attention as a means of achieving these requirements by its short process time and high annealing temperature, and hence low thermal budget, resulting in high dopant solubility.2-5 A problem exists with creating highly active profiles when boron is implanted in conjunction with a preamorphizing germanium implant; deactivation occurs during postactivation thermal processes. [6][7][8][9][10][11][12] This deactivation is thought to be driven by the release of silicon interstitials from end-of-range ͑EOR͒ defects that evolve through nonconservative Ostwald ripening during annealing. 13 The interstitials flow towards the surface and decorate the boron profile, producing boron interstitial clusters. [14][15][16][17] In this letter, multiple laser scan annealing at 1150°C followed by isochronal rapid thermal postannealing at lower temperatures is used to investigate the role of end-of-range defects in the redistribution and deactivation of ultrashallow B profiles in preamorphized and nonmelt laser-annealed silicon.N-type ͑100͒ Czochralski-silicon wafers were preamorphized with 5 keV Ge + to a dose of 1 ϫ 10 15 cm −2 producing a surface amorphous layer to a depth of ϳ15 nm. 500 eV B + was implanted into the amorphous layer to a dose of 1 ϫ 10 15 cm −2 . Both implants were made using an Applied Materials Quantum X implanter. The wafers were exposed to a scanning diode laser source operated under nonmelting conditions, which was used to anneal three strips across the wafers, corresponding to one, five, or ten scans at a temperature of 1150°C. By using multiple laser scans to anneal the wafer, it allows a study of defect evolution as a function of increasing the thermal budget. The amorphous layer regrew by solid phase epitaxial regrowth during the annealing. Samples were taken from these strips and annealed in dry N 2 for 60 s at temperatures ranging from 700 to 1000°C using a Process Products Corporation rapid thermal annealing system operating with a 50°C/s heating ramp rate. The van der Pauw technique was use...

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“…Compared with control samples, the LA sample with pre-annealing shows *a significant reduction of junction depth. [9] Figure 3 shows the junction depth and sheet resistance of samples annealed in various conditions. Compared with control RTA sample, the LA sample with pre-annealing shows much shallow junction depth while maintaining sheet resistance.…”

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confidence: 99%

Ultra-shallow Junction Formed by Plasma Doping and Laser Annealing

Heo

Hwang

2006

2006 14th IEEE International Conference on Advanced Thermal Processing of Semiconductors

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We investigated ultra-shallow junction prepared by plasma doping (PLAD) and laser annealing (LA). Although PLAD is promising doping technology for the sub-45nm technology node due to the high dose rate at low energy, it has problems which is related with hydrogen or fluorine. The implanted hydrogen generally increases damage in the Si substrate. The fluorine also retards dopant activation and increases dopant deactivation during post-annealing step. Conventional one step annealing processes such as rapid thermal annealing (RTA) or excimer laser annealing (LA) are not effective method for high dopant activation. To minimize the effect of hydrogen or fluorine, we propose additional pre-annealing followed by conventional laser annealing. By employing low temperature pre-annealing, we can improve electrical characteristics such as low sheet resistance, high activation rates, shallow junction depth and reduced dopant deactivation. The improvement can be explained by reduced defect density and out-diffusion of fluorine or hydrogen which in turn enhances dopant activation during ELA.

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Nonmelt laser annealing of 5-KeV and 1-KeV boron-implanted silicon

Cited by 37 publications

References 12 publications

Extended Defects Formation in Nanosecond Laser-Annealed Ion Implanted Silicon

Extended Defects Formation in Nanosecond Laser-Annealed Ion Implanted Silicon

Deactivation of ultrashallow boron implants in preamorphized silicon after nonmelt laser annealing with multiple scans

Ultra-shallow Junction Formed by Plasma Doping and Laser Annealing

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