Major challanges for
RF Linearity improvement performance of RFeSI (RF enhanced Signal Integrity substrate)
The 1st challenge consists of the improvement of RF linearity performances. 5G sub 6 GHz front-end module specifications continue to be more and more stringent in term of linearity, mostly considered through the attenuation scale expressed in dBm unit. An ultimate improvement of up to 30dBm is required vs the current 80 – 90 dBm existing products. During the timeframe of Beyond5program, according to RFSOI community consensus, develop an innovative substrate achieving a 10dBm linearity improvement without degradation over a wider temperature range is targeted
Cost effective RFeSI
The state of the art of the Beyond5 project would consider RFeSi product, as available for general-purpose market. Their performances are capable to achieve linearity requirement, but even exceed the specifications for power amplifier, diversity switches and low noise amplifier of the Front End Module. However, product cost is also critical to support market requirement. Accordingly, this part of the project will explore all materials & process alternatives in order to build a high volume manufacturing capable “General Purpose RFeSi” cheaper than the existing by 10 to 15%, while keeping its compliance with current device requirements.
FDSOI substrates for RF applications
The 3rd challenge is to combine FDSOI, initially designed for high performance / ultra-low power applications and RFSOI applications. SOITEC & SILTRONIC will develop an optimum substrate for GF 22FDX / 25 28FDSOI with RF add-ons.
300mm RF SOI substrate pilot line
The overarching objective of this task is to upgrade Soitec 300mm line initially developed for digital purpose to address specific challenges linked to RF application (such as High resistivity substrates and thicker isolation layer) in a new fabrication capacity called “Fab 5G”. This Pilot Line will enable the fabrication of SOI substrates in volume and quality in agreement with GLOBAL FOUNDRIES and ST for 22FDX-RF and RFSOI 65 nm requirements respectively.
The “Fab5G” includes construction of new building in Soitec, implementation of equipment, qualification of new processes opening the path to 1st industrialization of new 5G substrates. As detailed in SOITEC Product Roadmap, this pilot line aims to produce in adequate volume and quality 5 leading edge engineering substrates, beyond state of the art, answering 3 major challenges for 5G.
A 65 RFSOI PILOT LINE
RF SOI technology is today widely commercial deployed (~1.2 million 200 mm wafer per year) in order to manufacture 4G Front End Module using 180/130nm CMOS PD SOI technology. In order to address better performances required by 5G in C band (3.8GHz – 5GHz), ST is currently developing a new RF SOI technology moving to 65nm CMOS PD SOI node.
The main goal of this new 65RFSOI pilot line will leverage ST test vehicle < 6GHz in order to validate at device and circuit level (mainly simple antenna switch) possible performances improvement brought by innovative SOI substrate developed by Soitec.
ST will work with design partners in order to assess the relevance of its 65nm CMOS RFSOI technology to address NB IoT market.
The major ambition will be to fully integrate NB IoT SOC (FEM, Modem, RF) in 65nm CMOS PD SOI in order to deliver a cost effective solution to the IoT market.
The IoT market is just exploding and the number of connected devices is increasing every day. One of the key elements in this new industry is the connectivity, which has to deal with very strong constraints in power consumption and cost. The presence of LPWAN network is already important and several standards are in competition.
22FDX RF PILOT LINE
Globalfoundries 22FDX FDSOI technology is a recent entry into the semiconductor market. ST has had its 28nm FDSOI technology which has paved the way towards the emergence of FDSOI as a viable robust RF offering for Europe. GF has extended this initial 28nm to 22nm. GF 22FDX technology is now recognized as a viable technical alternative to the use of Bulk RFCMOS, SiGe BiCMOS, and FINFET technology for co-integrated LOGIC & RF FEM systems. Future growth opportunities for FDSOI in variety of market segments are summarized in the figure below. These are: Communications, Mobility, Internet of things, Automotive, RF & mm-Wave, and Aerospace and Defense.
FDSOI is a remarkable technology that can address a broad set of applications across all these segments as a premier SOC technology. The ability to combine low power computing with high performance RF/mm-Wave (especially for FEM) connectivity on one piece of silicon is unique for 22FDX. Additional areas of impact for FDSOI are Industrial Automation (Industry 4.0), Self-driving Vehicles (ADAS), Energy (Smart Grids), Automotive, Logistics, Medical, and Safety&Security.