InP-Si BiCMOS Heterointegration Using a Substrate Transfer Process

Abstract

Broadband transmitters for radio links in the mm-wave range are key building blocks for future wireless communication systems. In this work such components are to be realized by means of an InP-on-BiCMOS technology. This allows the combination of the favorable power performance of III-V transistors with the advantages of BiCMOS circuits such as complexity and integration density.This helps to avoid critical performance trade-offs compared to the pure III-V or BiCMOS versions. The heterointegration technology allows the integration of sub-mm-wave front-ends together with control logics and other lower-frequency components on a single chip. This drastically reduces packaging efforts. The strategy is to rely on BiCMOS as far as possible and to apply III-V elements only for functions for which they show clear superiority. In a first run the passive elements and the dc- and rf-interconnects between InP and BiCMOS were tested. This test showed the feasibility of the wafer bond process for the heterointegration of InP and BiCMOS. For that purpose a five metal layer Al back-end with silicon dioxide as interlayer dielectric was built on the silicon wafer. A three layer metallization (Au) in benzocyclobutene (BCB) as insulating dielectric represented the environment for the InP-HBTs. Thin film micro strip lines and special designed interconnects between the two metallization systems were characterized in dependence of frequencies up to 100 GHz to estimate the insertion losses.