High speed EELS composition analysis, in DualEELS mode, of metal alloy ohmic contacts for the fabrication of III-V MOSFET devices

As the size of III-V devices decreases, ohmic contacts and their performance becomes increasingly significant. In addition to low resistance, these contacts must be reproducible, show good lateral and depth uniformity and be thermally stable. AuGeNi ohmic contacts are widely used as they show a low contact resistivity and are typically compatible with the fabrication of III-V MOSFET devices1. However, they have the drawback of poor uniformity due to the diffusion of the Au into the III-V substrate. This diffusion is dependent on the temperature used during the annealing process after deposition of Au, Ge and Ni. It is clear that the performance of this type of contact will be influenced by both the material present and the degree of roughness at the interface with the III-V substrate; methods to analyze these materials at the sub-nanometer level are required.

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