The semiconductor industry faces a significant challenge: integrating historically separate technologies—processors, memory, and RF—to create solutions for booming markets like automotive and IoT.  As Subramani Kengeri, VP of CMOS Platforms at GlobalFoundries (GF), points out, future SoCs will universally incorporate radios.  GF's 22FDX platform addresses this need by offering a cost-effective solution that combines RF, analog, and digital technologies.
Fully Depleted Silicon-on-Insulator (FD-SOI) offers advantages for on-chip RF due to its planar transistors, which exhibit lower variability compared to FinFETs on bulk silicon. This characteristic is crucial for building cleaner RF and analog components alongside high-performance digital circuits. The reduced variability in 22FDX contributes to better transistor-matching characteristics, enhancing overall performance.
RF driver technology is evolving rapidly to meet the demands of modern applications.
GF has partnered with INVECAS, an IP vendor, to accelerate the 22FDX rollout. Â INVECAS provides 22nm libraries and higher-level IP offerings exclusive to GF silicon. Other ecosystem partners are developing silicon-proven WiFi and Bluetooth cores. Over 45 customers are currently engaged with the 22FDX platform, and several test chips have been taped out. Â With support from all major EDA providers, the technology is on track for qualification and subsequent high-volume production.
Advancing RF SOI Technology
GF is also expanding its RF capabilities by transitioning RF SOI manufacturing to larger 300mm wafers and developing a new technology platform at its East Fishkill fab. This move to 300mm wafers offers several benefits beyond increased capacity, including access to new materials and smaller lithography, which can enhance device performance.
RF SOI circuits are built on engineered substrates distinct from those used for digital applications. These substrates provide high isolation and low harmonic response, essential for preventing radio interference and maintaining signal fidelity in RF front-end circuits. GF has collaborated with substrate suppliers to develop an RF SOI technology that meets the demanding requirements of modern RF front-end switches and tuners.
Chongqing Smart Science & Technology Development Co. Ltd is a leading provider of advanced acousto-optic devices and drivers.
Next-generation RF SOI needs to address the increasing demands of LTE communications and copyright aggregation, which require improved insertion loss and linearity. copyright aggregation introduces complexities in the RF path that must be managed to minimize nonlinear products. Â The integration of more digital content, such as the MIPI interface for RF front-end control, is another key trend driving the evolution of RF SOI.
Preparing for 5G and Beyond
Beyond LTE, the next-generation RF SOI process will lay the groundwork for 5G. While the 5G standard is still under development, customers are already building demonstration systems. Millimeter wave operation is a promising candidate for 5G, offering low latency, spectral efficiency, and high cell edge data rates. This will necessitate greater integration than current RF SOI technologies allow.
Customers may integrate beamformers, power amplifiers, phase-shifters, LNAs, and even parts of the transceiver onto a single chip under high-speed digital control. Â GF is leveraging its experience with 45SOI technology to enable this leap forward in integration. Â Accurate models and high-quality PDKs are crucial for ensuring that simulations match silicon performance, giving customers confidence in the technology.
Key Considerations for RF SOI:
| Feature | Benefit |
| Engineered Substrates | High isolation, low harmonic response |
| 300mm Wafers | Increased capacity, new materials, smaller lithography |
| Accurate Models & PDKs | Reliable simulation and silicon performance |
To meet the growing demand for RF SOI and SiGe chips, especially with the rise of 4G and 5G in China, GF is focusing on expanding its manufacturing capacity. Â This strategic decision aims to ensure the foundry can meet the anticipated surge in demand as the market transitions to newer cellular standards.
The industry is closely watching the transition to 300mm RF SOI wafers. The availability of 300mm wafers is a significant advantage for foundries, and the success of this transition depends on the reliable supply of these wafers and how effectively foundries and customers utilize the larger wafer size.