AlN thin films deposited on different Si-based substrates through RF magnetron sputtering

Abstract

Various Si-based materials such as Si (100), Si (111), oxidized Si (SiO₂), and amorphous Si (α-Si) are used as substrates for the growth of c-axis-orientated AlN thin films using radio frequency magnetron sputtering. First, AlN is studied on various substrates under a fixed deposition condition. The results show that AlN deposited on monocrystalline silicon has different structures and stress properties from it deposited on amorphous Si-based layers because of the former’s alien growth mechanism at the initiation of growth. Of all the substrates, AlN sputtered on SiO₂ exhibits the best structure and morphologies. Then AlN is researched on SiO₂ with the RF power and gas flow ratio of N₂ to Ar varied. The results approve that among all chosen RF powers, AlN sputtered at 150 W has the strongest (002) crystal peak, the smallest root-mean-square (RMS) surface roughness of 2.74 nm, and the lowest tensile stress of 605 MPa, but the lowest deposition rate. For the gas flow ratio, AlN synthesized at the N₂ to Ar flow ratio of 3:1 represents the highest intensity of (002) texture, the smoothest surface with an RMS of 4.21 nm, but the relatively lower deposition rate and larger residual stress.