Review of add-on process modules for high-frequency silicon technology

Add-on process modules as enhancements for standard high-frequency silicon integration processes are discussed. Such modules can cost-effectively be added without any interference with the core process before (pre-process modules), during (mid-process modules), or after (post-process modules) the circuit integration. In addition, layout options providing a most cost-effective means of enhancement are discussed. High-resistivity silicon substrates, ferromagnetic thin-film integration, bulk micromachining, saddle-add-on metallization, spacer-substrate integration, and metal layer shunting are presented as examples in those categories.