This paper investigates the impact of the interconnect between the bottom and the top metal layers on the transistor RF performance of CMOS and silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies. State-of-the-art 32-nm silicon-on-insulator (SOI) CMOS and 120-nm SiGe HBT technologies are analyzed in detail. Measured results indicate a significant reduction in the unity-gain frequency (fT) from the bottom to the top metal layer for advanced CMOS technology nodes, but only a slight reduction for SiGe HBTs. The 32-nm SOI CMOS and SiGe HBT technologies have a reduction in the maximum oscillation frequency (fmax) from the bottom to the top metal layer of ∼ 12 % and 5%, respectively. By analyzing technology scaling trends, it is clear that SiGe HBTs can now achieve a similar peak fT at the top metal layer in comparison with advanced CMOS technology nodes, and a significantly higher fmax. Furthermore, in CMOS technologies, the top metal layer fmax appears to have reached a peak around the 45-65-nm technology nodes, a result which has significant implications.
- 32 nm
- maximum oscillation frequency
- millimeter wave
- SiGe heterojunction bipolar transistor (HBT)
- silicon-germanium (SiGe)
- silicon-on-insulator (SOI)
- unity-gain frequency.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering