In the last few years, a new trend emerged in semiconductor industries: Connecting everything with everything, also called the Internet of Things (IoT). For this space of applications, computing power does not matter as much as low leakage and/or low dynamic power at low cost.
With 22FDX, GLOBALFOUNDRIES offers a technology with less complexity than FinFET, same gate length scaling due to fully-depleted channels, and additional features like back-gate biasing which perfectly suits the IoT market needs [2].
This technology offers nFET (pFET) drive currents of 910µA/µm (856µA/µm) at 0.8V and 100nA/µm leakage. It can be extended down to pA/µm transistor and pA/bitcell leakages for ultra-low leakage applications and below 0.4V Vdd operation for ultra-low dynamic power applications. At the same time, it offers RF/analog characteristics superior to FinFET with fT/fMAX of 375GHz/290GHz and 260GHz/250GHz for nFET and pFET, respectively, which serves a huge range of RF and millimeter wave applications.
22FDX also offers a competitive SRAM bitcell with competitive 1.46mV-μm FinFET-like transistor mismatch coefficient (AVt). Extremely low minimum operating voltages (Vmin) are reported for both the high-density (HD) 0.110μm2 and high-current (HC) 0.124μm2 bitcells without any assist, showing 95% limited yield (LY) Vmin values of 0.6V and 0.5V for 64Mb HD and 128Mb HC arrays, respectively [3].
The co-integration of SOI and bulk devices on the same wafer expands the device suite to very efficient diodes, bipolar devices, capacitors, and LDMOS.
Main features are FDSOI substrate for nFET, SiGe channel for pFET and dual in-situ doped raised source/drain epitaxy. Despite the utilization of the majority of process steps from the 28nm technologies, a logic/SRAM die scaling of 0.72x/0.83x relative to the 28nm technology node is achieved. All of the above combined enables cost-efficient manufacturing.
Back-gate biasing is a unique feature in FDSOI technologies which allows altering the I/V curves of individual devices up to whole blocks of circuitry to boost performance or minimize leakage wherever needed. This feature gives an additional degree of freedom to circuit and chip designers to optimize their products. Some examples will be shown.
Furthermore, GLOBALFOUNDRIES is in development of 12FDX, the next FDSOI technology node, which offers further area scaling at enhanced performance and extended features.
References:
[1] C. Auth et al., VLSIT, p.131-132 (2012)
[2] R. Carter et al., IEEE International, p. 2.2.1 - 2.2.4 (2016)
[3] V. Joshi et al., VLSIT, p.222-223 (2017)