(Invited) Substrate and Device Engineering for Iot and Automotive
Authors: Sellier Manuel 
Published: February 2020

The main challenges of the semiconductor industry have long revolved around density scaling and performance improvement of ICs. However, a growing proportion of semiconductor consumption is now driven by factors other than pure performance and density. The Internet Of Things (IoT) & Automotive markets are perfect examples of this, where increased energy efficiency combined with enhanced reliability and heterogeneous functions integration capabilities have become major hurdles to overcome.
Advanced substrates such as Silicon-On-Insulator (SOI) are progressively emerging as key platforms to address these pain points. In fact, the choice of advanced substrates results from a tradeoff between device and substrate complexity with regards to system level challenges. Bringing all the complexity of device implementation and integration on the device manufacturing process - rather than the substrate - turns out to be less and less relevant to address the challenges of heterogeneous functions integration, reliability and power efficiency.
In this talk, we will discuss how three engineered substrate platforms, namely Power-SOI, RF-SOI and FD-SOI, are currently reshaping IoT and Automotive with new industry standards.

Power-SOI

Power-SOI substrates are based on thick BOX and top silicon (typically 1µm or more). They address high voltage device integration challenges. They allow for the replacement of all leaky and area consuming junction isolation techniques by oxide isolation, bringing significant advantages in terms of device characteristics (higher RDSON, lower leakage, lower area), but also in terms of reliability (latch-up free operation) and integration with high voltage power devices up to 600V integrated with digital functions on the same substrate. Power-SOI offers therefore tremendous benefits for power management ICs and is particularly advantageous for automotive applications.

RF-SOI

RF-SOI is based on a high resistivity base material often combined with a low mobility layer just beneath the BOX. RF-SOI allows the integration of ultra high linear and low loss RF components within the same substrate. This unique capability has made RF-SOI the de facto technology for a growing number of smartphone Front-End-Modules (FEM) components (switch, LNA, PA, duplexers…), i.e. all the RF components linking the antenna and the transceiver. RF-SOI will continue to expand into new applications like automotive where high throughput and low latency connectivity will be key. RF-SOI will also bring major value in the IoT space, as its integration capability offers a single FEM chip solutionwhich is particularly beneficialat system level.

FD-SOI

FD-SOI is the natural technology for the continuation of Moore’s law for battery-powered and cost-sensitive applications. FD-SOI is actually the simplest platform enabling fully depleted operation of transistors, which is a fundamental advantage to go below the 28nm node. FD-SOI substrates havean ultra thin top layer and BOX. The benefits of FD-SOI are numerous: simple device manufacturing, high Fmax compatible with mmWave spectrum, ultra low voltage operation down to 0.4V,
All these characteristics have made FD-SOI a key technology for all applications not purely driven by density and digital performance. In automotive, it brings huge differentiation in terms of reliability and power consumption, enabling the possibility of highly reliable fanless solutions. In IoT, significant battery life gains can be expected, while providing the best cost per transistor of all CMOS technologies.

Conclusion

Advanced substrates such as SOI appear more and more as key platforms to ease integration, while exacerbating device advantages such as power and reliability for a growing number of applications not purely driven by density and performance. These key features will probably impose SOI in the future as a new industry standard for IoT and automotive.