Oxidation-resistant capping layers

Dielectric Film Deposition. Dielectric films are found in all VLSI circuits to provide insulation between conducting layers, as diffusion and ion implantation (qv) masks, for diffusion from doped oxides, to cap doped films to prevent outdiffusion, and for passivating devices as a measure of protection against external contamination, moisture, and scratches. Properties that define the nature and function of dielectric films are the dielectric constant, the process temperature, and specific fabrication characteristics such as step coverage, gap-filling capabihties, density stress, contamination, thickness uniformity, deposition rate, and moisture resistance (2). Several processes are used to deposit dielectric films including atmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), or plasma-enhanced CVD (PECVD) (see Plasma technology). 

After the anodization process, most of the time, a stabilization annealing at low temperature (below 500 °C) is performed in an O2 or in a N2 ambient. In some cases, an oxidation annealing is performed at higher temperature. Afterwards, a thin oxide cap layer is generally deposited to seal the pores and to ensure a complete DC isolation between the substrate and the device. Various metal layers can be used for the strips. To reduce the ohmic losses, low-resistivity metals must be used... 

The reversible switching of Mg-TM (TM = Ni, Co, Fe, Mn) films was discovered by Richardson et al. [97, 98]. While in bulk samples hydrogenation requires high temperatures (500 to 600 K) and pressures of 10 to 10 Pa [99,100], for thin films it occurs readily at room temperature at low pressures when they are capped with a thin Pd layer. This class of materials does not involve rare-earth metals and might therefore be more resistant to oxidation than the earlier mirrors. This is especially important for applications. 

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