At the SEMICON West trade show in San Francisco (9-11 July), Soitec of Bernin, France, which makes engineered substrates - including silicon-on-insulator (SOI) wafers and III-V epiwafers - as well as concentrating photovoltaic (CPV) solar systems, said that its silicon-on-insulator (SOI) technologies are now mainstream for manufacturing switches and antenna-tuners (key RF components used in all cell phones and tablet computers).
According to the market research firm Yole Développement, more than 65% of substrates used in fabricating switches for handsets are SOI-based, showing the massive adoption of RF SOI for this booming electronic market experiencing double-digit growth. Now, chip manufacturers are relying on SOI technology to offer the best price/performance ratio and enable next-generation smartphones.
Soitec says that its engineered substrates are at the heart of RF integrated circuits, enabling chip manufacturers to integrate various functions on the same die, reducing the overall system cost. An RF SOI substrate features an active layer on which CMOS transistors are built, isolated from a high-resistivity silicon base layer. This reduces noise and interference, helping the finished die to reach its target performance in terms of signal integrity, handling RF power and integration density. SOI technologies enable devices to reach a figure of merit for on-series resistance and off-equivalent capacitance (Ron.Coff) below 200fs (femtoseconds), with the potential for further reduction, reckons Soitec. This directly relates to improved device performance and smaller die size.
Another driver of SOI's growth is the evolution towards the greater performance required for overhauling wireless networks from 3G to 4G/LTE and further LTE Advanced using carrier aggregation. Soitec adds that SOI technologies exceed stringent linearity requirements such as intermodulation distortion (IMD) far beyond -110dBm, helping to avoid interference with other networks.
"RF SOI technologies enable the device integration, cost effectiveness and high performance needed for high-volume 3G and LTE applications," says Bernard Aspar, VP, Communication& Power business unit at Soitec. "RF, with over 100% revenue growth last year, remains a strategic market in which we have been continuously investing for more than a decade."
Soitec says that, on the strength of recent demonstrations, power amplifiers will likely be the next RF components based on SOI, as the technology enables highly tunable amplifiers to address multi-region requirements on a single platform. The firm adds that its RF SOI substrates offer a path towards further integration, such as more mixed-signal and digital content.
Soitec also says that its broad offerings allow RF device manufacturers to select an engineered substrate that aligns best with their market strategies — from low-cost GSM handsets to multi-band, multi-mode LTE smartphones and tablets.
