The early use of sapphire in the substrate for RF-SOI wafers — used by Peregrine Semicondcutor’s RF ICs — eventually transitioned to silicon, explained Boudre, to lower the cost. Thanks to Soitec’s collaboration with the Université Catholique de Louvain, the new RF-SOI wafers maintained low RF insertion loss and reduced crosstalk, similar to quartz substrates, Soitec explained. The two parties joined forces to develop a “trap-rich layer” for RF-SOI wafers, which eventually made it possible to combine silicon CMOS circuits on a RF substrate.
RF-SOI, now a standard in front-end modules, is “used in 100 percent of smartphones,” according to Soitec. But the company is not standing still.
Bourdre said, “Further developments of the technology are taking place to address the next RF requirements.” Think advanced LTE, uplink carrier aggregation, massive MIMO, 5G with mmWave, he noted.
For switches, antennas and tuners of 4G and 5G, sub-6GHz front end, Soitec believes that RF-SOI is critical. Cellular operators are pushing supply chains, including system and fabless chip companies. RF-SOI wafer suppliers like Soitec are working on new materials. Bourdre also mentioned that Soitec is currently working on new engineered substrate using materials such as piezoelectric — to develop “piezoelectric on insulator.” That will be used for SAW filters, Bourdre said.
Photonics-SOI for data centers
Soitec is also counting on the growth of Photonics-SOI wafers, as demand soars for high-speed optical links in data centers and communication infrastructure.
There are clear advantages in leveraging Photonics-SOI. It allows a path for wavelength multiplexing, bringing the optical transceiver closer to the chip (thus lowering propagation loss). Photonics-SOI also provides higher throughput than direct light modulation and enables “100G and 400G transceivers,” according to the company. Perhaps most important is cost. Photonics-SOI wafers allow standard CMOS fabs to produce optical transmitter and receiver chips.
Companies such as Intel and Cisco have been actively engaged in Photonics-SOI modeling for their silicon photonics.
Imager-SOI for NIR sensors
Clearly, Soitec sees a growing opportunity for its Imager-SOI. Without naming any customers, Soitec listed a number of advantages of Imager-SOI. These include the ability to lower NIR illuminator power consumption, better performance through increased signal to noise ratio, and keeping cost down — because of its “lower die size” compared to bulk for the same resolution.
According to Yole’s Cambou, “Apple’s adoption of ST’s NIR sensors marks the debut of SOI in mass production for image sensors.” He added, “Image sensors are characterized by large surface due to the physical size of light. Therefore, this is a great market to be in for a substrate supplier” like Soitec.
Evolving business strategy
Soitec, founded in 1992, has gone through a few management changes, and in business strategies and target markets. Dorian Terral, a financial analyst at Bryan, Garnier & Co. wrote in a research note a year ago that “although Soitec suffered from a complex history, the arrival of a new management team in 2015 and the work carried out since have clearly renewed the group’s profile.”
Boudre asserts that Soitec’s turnaround “is behind us.” While Soitec “can’t afford to try and test everything” for new engineered substrates, he said that his company today is much better equipped to read the market and tune its technologies for bigger opportunities.
Boudre explained, “Ten years ago, Soitec was focused on an R&D platform” used in labs. “Today, we are closely working with our customers and our customers’ customers.”
To drive design wins, Boudre explained, “We brought in a lot of people capable of talk the talk” with customers in such areas as RF, imagers, power and IoT, and understand what customers’ customers need.
For tomorrow, “Soitec plans to be more focused on the development of innovation platforms.” A case in point is Soitec’s plan to closely work with China Mobile. To be an effective player, Soitec needs to be tuned to the 5G decision-making process.
Qorvo earlier this year became the first RF supplier to join the China Mobile 5G Innovation Center — an alliance created to develop 5G solutions for China. Soitec is also in the process of joining the alliance.
The plan is to “create the innovation platform for 5G together with China Mobile, and to qualify the technology by 2019,” Boudre said.
Acknowledging the fast-changing tech industry landscape, the Soitec CEO said, “We want to know what China Mobile wants, what Alibaba is looking for, and what Google is doing.”
— Junko Yoshida, Chief International Correspondent, EE Times