The World’s First 2Xnm embedded MRAM for GP-MCU, and an Overview of mmWave Capabilities for 5G Applications, Generate Strong Interest
22FDX® technology created quite a stir when it took the stage at two major international conferences recently, which shows that it is opening up new horizons for customers in today’s fastest-growing semiconductor markets.
At the VLSI Technology Symposium in Kyoto, Japan, some 500 people listened to GF Fellow Danny Shum describe a 22FDX manufacturing breakthrough in embedded STT-MRAM non-volatile memory (eMRAM). In fact, following his talk the audience continued to pepper him with questions as the five-minute Q&A time ran out and throughout the subsequent 20-minute break before the next session. They covered the waterfront, from questions about specific technical details like the material stack, process technology, test results and tooling; to broader issues including product roadmap, business strategy, partnership opportunities and PDK availability.
This strong interest stems from the view that eMRAM technology promises to displace the eFlash NVM now used for code storage and working memory in general-purpose microcontrollers and IoT devices, which are in high demand. GF, with its partner Everspin Technologies, demonstrated the capability to use eMRAM in applications requiring high reliability in harsh environments, such as automotive SoCs.
The full VLSI paper, CMOS-embedded STT-MRAM Arrays in 2x nm Nodes for GPMCU applications, is available for download on the GF website.
Meanwhile, at the IEEE International Microwave Symposium in Honolulu, Hawaii, GF Senior Fellow and RF Chief Technical Officer David Harame outlined the benefits of partially and fully depleted SOI technology (the basis for 22FDX) for RF millimeter wave (mmWave) applications in forthcoming 5G devices. His talk was part of a workshop session he and GF colleagues Ned Cahoon, Baljit Chandhoke and Anirban Bandyopadhyay organized on how silicon technologies and especially 22FDX are now ripe for deployment in mmWave applications versus older, more specialized and costlier technologies.
Together, the talks illustrate the versatility of 22FDX for an ever-expanding range of uses in automotive, mobility/RF connectivity, Internet of Things (IoT), networking and other applications.
An increasing number of applications now require chips that contain embedded non-volatile memory (eNVM), but as devices scale smaller and low-power operation becomes ever more critically important, traditional eFlash NVM is increasingly challenged. That’s because of its relatively high voltage requirements and the difficulty in scaling a key component – its tunnel oxide – without comprising performance and reliability.
A number of alternative eNVM technologies exist, but while eMRAM has long been seen as potentially offering the best combination of scalability, write speed, memory retention, long-term reliability and low-power operation, until now no commercially viable high-density STT-MRAM embedded memory array had ever been demonstrated.
That is, not until Shum announced one at the VLSI conference. He described how GF in collaboration with Everspin Technologies built and demonstrated the world’s first 40Mb CMOS array with an integrated eMRAM at 2x-nm design rules.
A key attribute is its ability to withstand temperatures of 260ºC for at least five minutes, meaning that the typical solder reflow steps required for packaging and final assembly will not change the memory contents, and that code storage can be performed during wafer probe. In addition, the GF 22FDX eMRAM is designed to retain data for more than 10 years at 150°C, which allows the technology to be considered for use in automotive SoCs.
Other important features are that the memory is fabricated at the back-end-of-the-line (BEOL) so that sensitive logic devices and circuitry aren’t damaged during high-temperature front-end-of-the-line (FEOL) process steps. This also enables reusable IP because the same PDK is used. The memory array also runs off the chip’s core voltage power supply (Vdd and I/O), with no need to charge-pump the voltage.
GLOBALFOUNDRIES will offer eMRAM technology as part of its overall 22FDX portfolio of solutions next year, and will begin customer prototyping on multi-project wafers (MPWs) late this year.
22FDX Silicon for mmWave
At the Microwave Symposium, Harame described how the market for high volumes of silicon-based chips operating at mmWave frequencies is blossoming because of the move to 5G wireless standards. (See also, Executive Perspective: Everything’s Going Wireless, And RF Chips Are Enabling It)
He explained how partially and fully depleted SOI technology (PDSOI and FDX, respectively) is a cost-effective silicon-based platform well-suited for these uses because it features low transistor leakage current (e.g., low parasitics).
Already, he noted, there is a broad base of experience with SOI technology because cellular and Wi-Fi switches are widely built using SOI technologies at older technology nodes. One example is 45nm PDSOI, which also has been investigated for many mmWave phased-array system applications. That’s because the ability to stack transistors in PDSOI greatly increases power-handling capabilities even as it enables switches and power amplifiers to be built using low voltage CMOS devices.
His talk focused on how FDX extends such performance to even higher levels because of its high-k dielectric/metal gate stack (high-k/MG), 22nm gate length, and thin silicon channel, which all combine to make it well-suited for forthcoming 5G mmWave applications.