Tilted fiber texture in aluminum nitride thin films

Abstract

The authors report a strong dependence of fiber texture tilt angle on the gas composition in aluminum nitride (AlN) thin films prepared by off-normal reactive magnetron sputtering in N2∕Ar mixtures. Using x-ray pole figures, they measured the c-axis AlN tilt angle as a function of N2 flow ratio for a deposition angle of 42° from normal. They found that the c axis remains perpendicular to the substrate for a N2 flow ratio up to 12%–15% and then abruptly shifts towards the deposition direction for a N2 flow ratio above 12%–15%. They also identified a range of deposition parameters at lower N2 flow in which an amorphous phase of AlN is formed. The authors attribute the tilted fiber texture to the energetic atom flux causing less damage and resputtering in grains oriented with open channeling directions, compared with nonchanneling directions in AlN. The abrupt change in fiber tilt angle versus gas composition is attributed to the adatom mobility being quenched above 12%–15% N2 flow.