• Sharp, J. A.
• Jeynes, C.
• Sealy, B. J.
• Gwilliam, R. M.
• Kirkby, Karen Reeson
• Hamilton, J. J.

Abstract

<p>This paper investigates the electrical activation of boron halide molecular implants into silicon and compares them to boron implants at the same effective energy. The implanted species: B⁺, BF2+, BCl2+ and BBr2+ were implanted to doses of 2 × 10¹⁴ and 1 × 10 ¹⁵ B cm^-2 the energy of the molecular implants was calculated to give an effective boron implant energy of 5 keV. Samples cut from the wafers were annealed for 30 s at temperatures ranging from 800 °C to 1100 °C. Hall effect measurements were used to compare and contrast the electrical activation of the boron between the different halide species and doses. It was found that molecular implants of BBr2+ and BCl2+ do not enhance the electrical activation of boron to the same extent that BF2+ implants do. The BBr2+ implants are only comparable with boron after annealing at high temperatures (above 1000 °C). The BF2+ implants show enhanced electrical activation with respect to boron for all the annealing temperatures and doses studied. Rutherford backscattering spectroscopy (RBS) of silicon implanted with BBr2+ to a dose of 1 × 10¹⁵ boron atoms cm^-2, shows that an amorphous region is created during the implantation. This region fully re-grows after annealing at 1100 °C; lower temperature anneals remove only part of the amorphous layer. RBS channelling shows that a fraction of the bromine takes up substitutional lattice sites upon implantation, and that this fraction increases as the samples are annealed at temperatures above 600 °C with 40% of the B being in substitutional sites after annealing at 1050 °C.</p>

Topics

• impedance spectroscopy
• amorphous
• Silicon
• Boron
• annealing
• activation
• Rutherford backscattering spectrometry