Improving the structural performance of low-temperature sputtered AlN on silicon substrate

Abstract

Preparing high-quality AlN films at low temperatures is always highly demanded in plenty of application-fields, despite the high temperature is always necessary to enable the AlN crystallization. Therefore, improving the structural properties at low temperature is still challenging in the field. In the present work, the metal organic chemical vapor deposition (MOCVD) grown AlN nucleation layer is employed to improve the crystallinity and morphology of sputtered AlN on 6-inch Si (111) substrate at the temperature even as low as 100℃ where it is not principally possible to achieve the crystallization of sputtered AlN. When compared with the as-sputtered AlN prepared even at 650℃, it is found that the full width at half maximum (FWHM) of AlN (002) X-ray rocking curves is intensively decreased to 0.96° from 1.61°, and such a reduction indicates that the screw dislocation density is decreased from 7.31×1010 down to 2.14×1010/cm2. In addition to the crystallinity, the morphology is also obviously improved that the root-mean-square (RMS) roughness is reduced from 4.99 nm down to 0.83 nm in a scanned area of 3×3 μm2 through introducing AlN nucleation. Therefore, such a combination highlights the contribution of AlN nucleation grown by MOCVD in improving the structural properties of low-temperature sputtered AlN layer which is compatible with the manufacturing of Si integrated circuits.