DEVELOPMENT OF PREFERRED ORIENTATION IN POLYCRYSTALLINE TIN LAYERS GROWN BY ULTRAHIGH-VACUUM REACTIVE MAGNETRON SPUTTERING

The preferred orientation of polycrystalline TiN films grown by ultrahigh-vacuum reactive-magnetron sputter deposition on amorphous SiO2 at 350 degrees C in pure N-2 discharges was controllably varied from (111) to completely (002) by varying the incident ion/metal flux ratio N-2(+) ion energy E(i) maintained constant at similar or equal to 20 eV (similar or equal to 10 eV per incident J(i)/J(Ti) from 1 to greater than or equal to 5 With the N-2(+) accelerated N). All samples were slightly over-stoichiometric with N/Ti=1.02+/-0.03. Films deposited with J(i)/J(Ti) = 1 initially exhibit a mixed texture with competitive columnar growth which slowly evolves into a nearly complete (111) texture at film thicknesses greater than 1 mu m. However, films grown with J(i)/J(Ti)greater than or equal to 5 exhibit an essentially complete (002) preferred orientation from the earliest observable stages. The normalized XRD (002) intensity ratio in thick layers increased from similar or equal to 0 to 1 as J(i)/J(Ti) was varied from 1 to greater than or equal to 5. Both (111) and (001) interplanar spacings remained constant as a function of film thickness yielding a lattice constant of 0.4240+/-0.0005 nm, equal to that of unstrained bulk TiN. Contrary to previous models, the present results establish that TiN preferred orientation can be controlled without introducing large in-plane compressive stress and/or changes in the strain energy as a function of layer thickness. (C) 1995 American Institute of Physics.