Investigation of the structure and properties of a-C : H coatings with metal and silicon containing interlayers

The structure of the interface of a-C:H coatings deposited with metal and S i-containing interlayers has been studied. Carbide forming metals (Al, Ti, Cr) can improve the chemical bonding compared with a substrate material whi ch does not form carbides extensively by itself. In addition, a graded tran sition zone enlarges the interface between the carbon layer and the interla yer metal. In the present work the metal atoms were evaporated and ionized into a dense Ar plasma and deposited onto Si (100) substrates. A graded int erface between the metal interlayer and the a-C:H coating was produced by i ntroducing C2H2 with increasing amount into the Ar/He plasma during the PAP VD metal deposition process. The PACVD a-C:H deposition process was continu ed after the termination of metal evaporation to produce the pure a-C:H top layer. Further to Al-, Cr-, Ti- and Cu-interlayers, Si-containing interlay ers were investigated. The Si-containing interlayers were deposited by a PA CVD process using tetraethoxysilane Si(OC2H5)(4) (TEOS) and tetramethylsila ne Si(CH3)(4) (TMS). The characterization of the deposited layer systems was performed by SIMS, SNMS and XPS analyses as well as SEM and analytical TEM methods. (C) 2001 E lsevier Science B.V.. All rights reserved.