Deposition and Properties of AlN/TiN & AlN/ZrN Superlattice Coatings

• Main Authors: Gwo-Yih Hsiao, 蕭國益
• Other Authors: Ming-Show Wong
• Format: Others
• Language: en_US
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/24045468298732152343

碩士 === 國立東華大學 === 材料科學與工程研究所 === 87 === This project studies the preparation and properties of a new class of advanced multilayered AlN/TiN and AlN/ZrN coatings. It investigates the relationships among processing methods and the coating microstructure and properties and facilitates the understanding of property enhancement observed in the coatings. Advanced ion-assisted, high-rate, reactive dc and pulse dc magnetron sputtering technique combined with several innovative methods and processing strategies is used to deposit the nitride coatings. AlN exhibits polymorphism depending growth conditions. The most stable form under standard condition is hexagonal wurtzite structure. Multilayer coatings of AlN/TiN and AlN/ZrN have been deposited onto various substrates such as silicon (111) or (100) wafer and glass slide and stainless steel simultaneoususly using a dual-cathode reactive unbalanced dc magnetron sputtering system. AlN/TiN coatings are prepared by sputtering from Al and Ti targets , AlN/ZrN sputtering from Zr and Al targets in side-by-side configuration in Ar + N2 atmosphere, onto various substrates fixed on a rotating substrate holder. The rotation of the substrate holder varied from 0.1 to 16 r.p.m. corresponding to a unit bilayer thickness (Λ) of 1-10 nm. The total film thickness of AlN/TiN and AlN/ZrN were about 1~2 μm. Structural characterization were performed by measure of X-ray diffraction. The Vickers microhardness in the load 25 g was measured. Depending on the unit bilayer thickness and substrate bias, hardness valves of 1000-3300 kgf/mm2 were obtained at the bulk (thin film + substrate). It was found that under a critical thickness about ~2.2nm for the AlN layer the AlN/TiN nanolaminates exhibit a highly textured [111] orientation superlattice structure and an enhancement in film hardness up to 3300 kgf/mm2. X-ray diffraction indicate that in the highly textured [111] orientation AlN/TiN multilayers, AlN has transformed into a nano-stabilized cubic form from the normal hexagonal phase. XRD patterns indicate AlN/TiN superlattice structure not only is affected by on the unit bilayer thickness but also substrate bias. However, in the case of AlN/ZrN multilayers, no stabilization of cubic AlN was observed under the growth conditions comparable to those for AlN/TiN multilayers. The effect of stress and lattice mismatch on the hexagonal-to-cubic transformation is discussed.