Base contact material issues of integrated high-speed Si/SiGe heterojunction bipolar transistors

摘要

Base contact issues of a Si/SiGe heterojunction bipolar transistor with a shallow implanted base are described. A silicide, required for low resistivity contact, could reach the base-collector space-charge region due to silicide roughness. Cobaltsilicide offers a solution to the contacting of the base. In this case the reaction of the cobalt with a cap-layer has to be reduced and the roughness of the cobaltsilicide has to be optimized by well chosen process parameters.