LASER-INDUCED REACTIVE CRYSTALLIZATION OF METASTABLE BN FROM COPPER IMPLANTED WITH B+ AND N-2(+) IONS

Ion implantation followed by an excimer laser irradiation was used for the crystallization of metastable boron nitride (BN) films. Plates of polycrystalline copper (3 mm diameter) thinned locally to permit their observation in the transmission electron microscope (TEM) were implanted with boron ions (B+) and nitrogen ions (N-2(+)). The ions were implanted with an ion energy of 100 keV and ion dose of 1.0 x 10(18) ions cm(-2). The as-implanted copper specimens were subsequently irradiated with nanosecond pulsed XeCl excimer laser of beam energy of 43 mJ, wavelength 308 nm pulse duration of 10 ns. The penetration depth of the implanted ions was estimated roughly at R(L) = 700 nm for B+ ions and R(L) = 200 nm for N-2(+) ions. TEM examinations have indicated that the layers thus formed were boron nitride (BN) films. Results have shown that the phase content of boron nitride crystallized appeared to depend largely on the sequence of ion implantation. When boron ions were implanted, first BN of the wurtzite (w-BN) type and then E-BN phases were formed, whereas when nitrogen ions were implanted first only the E-BN phase was crystallized.