Specific Process Knowledge/Thin film deposition/Deposition of Gold/Adhesion layers: Difference between revisions
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Fig. 1 represents the simplified adhesion layer model usually used in the micro and nanofabrication community for a generic bilayer system. In this model, the adhesion layer and the noble metal over-layer are deposited sequentially by PVD and are considered to be completely uniform and in perfect contact. Ti and Cr are known to be more chemically reactive than noble metals and thereby increase the adhesion as they chemically bind to the substrate. However, the model does not include any layer-layer interaction. Moreover, it is considered to be independent of the thin-film thickness. Due to the continuous miniaturization of structures and devices, the total metal thin-film thicknesses have reached tens of nanometers, with the thickness of the over-layer approaching the one of the adhesion layer. In these conditions it is unclear if the simplified model is still adequate. | Fig. 1 represents the simplified adhesion layer model usually used in the micro and nanofabrication community for a generic bilayer system. In this model, the adhesion layer and the noble metal over-layer are deposited sequentially by PVD and are considered to be completely uniform and in perfect contact. Ti and Cr are known to be more chemically reactive than noble metals and thereby increase the adhesion as they chemically bind to the substrate. However, the model does not include any layer-layer interaction. Moreover, it is considered to be independent of the thin-film thickness. Due to the continuous miniaturization of structures and devices, the total metal thin-film thicknesses have reached tens of nanometers, with the thickness of the over-layer approaching the one of the adhesion layer. In these conditions it is unclear if the simplified model is still adequate. | ||
[[File:Picture00.png|650px|center|thumb|Fig. 1: Schematic representation of a substrate, adhesion layer and overlayer system. The substrate is either a dielectric or semiconductor material and the over-layer is a metal.]] | |||
Here the first recommendations on the adhesion layers best suited for specific nanodevice applications are presented. Below the background and characterization work carried out on on two main thin-film systems, Cr/Au and Ti/Au stacks to arrive at these recommendations is presented. | |||
= Adhesion layer effect on Au thin films = | = Adhesion layer effect on Au thin films = | ||