Electrical properties of metals in Si and Ge

Abstract

First the attention is given to some important metals commonly used in semiconductor manufacturing, implying that they are intentionally introduced in some of the process steps (e.g. as silicides, metal layers, diffusion barrier, hard masks, gate dielectric etc.). The risk that they act as a contaminant degrading the device properties has to be minimized but can in some cases not be avoided. Sections 6.1–6.3 discuss the behavior and properties of nickel, cobalt, and chromium. Sections 6.4–6.8 review the knowledge about titanium, molybdenum, palladium, platinum and gold. The other 3d transition metals scandium, vanadium, manganese and zinc are the subject of sects. 6.9–6.12. The 4d metals including zirconium, niobium, ruthenium, rhodium, silver and cadmium are treated in sects. 6.13 to 6.18. Finally the 5d transition metals hafnium, tantalum, tungsten, rhenium, osmium, iridium and mercury are addressed in sects. 6.19–6.24. For all of these metals, first their configuration in the semiconductor lattice, i.e., interstitial and/or substitutional position, interactions with dopants and other transition metal, cluster formation, precipitates and behavior during thermal anneal are analyzed. Then the electrical properties are reviewed, including the different energy levels in the band gap and the impact on electrical performance parameters. Finally the detection and identification techniques are discussed.