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

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 thei r observation in the transmission electron microscope (TEM) were impla nted with boron ions (B+) and nitrogen ions (N-2(+)). The ions were im planted with an ion energy of 100 keV and ion dose of 1.0 x 10(18) ion s cm(-2). The as-implanted copper specimens were subsequently irradiat ed with nanosecond pulsed XeCl excimer laser of beam energy of 43 mJ, wavelength 308 nm pulse duration of 10 ns. The penetration depth of th e implanted ions was estimated roughly at R(L) = 700 nm for B+ ions an d R(L) = 200 nm for N-2(+) ions. TEM examinations have indicated that the layers thus formed were boron nitride (BN) films. Results have sho wn that the phase content of boron nitride crystallized appeared to de pend 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.