Soitec puts eSI substrates into mass production
These SOI type wafers are suited to the manufacturing of the latest 4G/LTE smartphones and RF devices
French firm Soitec has commenced high-volume manufacturing of its new Enhanced Signal Integrity (eSI) substrates, enabling cost-effective and high-performance radio-frequency (RF) devices.
The company's innovative eSI products are produced using Soitec's proprietary Smart Cut technology.
Soitec's Smart Cut process is based on silicon on insulator (SOI) technology and refers to the use of a layered silicon-insulator-silicon substrate in place of conventional silicon substrates in semiconductor manufacturing, especially microelectronics, to reduce parasitic device capacitance.
The eSI wafers are claimed to be the first "˜trap-rich' type of material in full production. They are already used in manufacturing by many RF foundries and have been adopted as one of the preferred substrates for 4G and LTE mobile computing and communication applications.
These substrates, on which devices are manufactured, have a significant impact on the final devices' performance. Soitec's eSI substrates are designed by introducing an innovative material (a trap-rich layer) between the high-resistivity handle wafer and the buried oxide.
This layer limits the parasitic surface conduction present in standard high-resistivity silicon-on-insulator (HR-SOI) substrates, boosting the performance of RF devices.
Because this layer is built into the substrate, it reduces the number of process steps and relaxes design rules, leading to a lower cost process and possibly a smaller die area per function. RF designers can therefore integrate diverse functions such as switches, power amplifiers and antenna tuners with excellent RF isolation, good insertion loss, better thermal conductivity and better signal integrity than other technologies.
This is according to data from the Université catholique de Louvain (UCL), Belgium. The scientists found that eSI substrate shows RF losses below 0.15 dB/mm at 2 GHz, improved second harmonic by more than 20 dB and improved crosstalk by 20 dB at 1 GHz compared to standard HR-SOI.
"Our proprietary eSI product, developed and fine tuned during the past few years, is now qualified by several key customers and is already being used in volume production of mobile handsets on today's market," says Bernard Aspar, Senior Vice President and Soitec's Communication & Power Business Unit General Manager.
"As we are continuing to pioneer innovation in RF-engineered substrates, we are very pleased to deliver a technology that enables market-leading companies to be successful with a cost-effective RF device solution addressing stringent 4G and LTE requirements."
The new eSI product is part of the Soitec Wave SOI product family, and it complements the company's well-established HR-SOI product line. These HR-SOI substrates are already used today in many smartphones, making them the mainstream engineered substrates for switches.
While standard HR-SOI is capable of meeting 2G and 3G requirements, eSI substrates achieve much higher linearity and isolation, allowing designers to address some of the most advanced LTE requirements at a competitive cost.