On-wafer RF Figure-of-Merit Circuit Block Design for Technology Development, Process Control and PDK Validation

The inclusion of circuit-level blocks, such as ring oscillators, operational amplifiers and A/D or D/A converters, in technology characterization test chips is now a well-established practice. Such figure-of-merit (FoM) circuit blocks provide a means of judging technology performance and variability on-wafer during the technology development phase. In addition, FoM blocks are used to validate the ability of a PDK in capturing process behavior. This paper describes an extension of this concept to the RF domain, for a high-performance 0.18mum SiGe:C-BiCMOS technology. The design of six different RF-FoM blocks, typically found in a transceiver, is presented. Test structure design considerations, including layout, pad-frame choice and probe-card design, are described. Finally, measured statistical results are presented. These designs enabled PDK verification and high-volume yield product samples.