MRAM: a promising new life after eFlash – An interview with GlobalFoundries

Among the various emerging non-volatile memory (NVM) technologies, spin transfer torque magnetoresistive RAM (STT-MRAM) is gaining steam – especially for embedded memory applications – thanks to the growing involvement of top foundry/IDM players and equipment suppliers. There is consensus in the industry that 28/22nm will be the end of eFlash, not because of scalability limitations but because of economic barriers, and therefore a new embedded NVM for code/data storage is needed. At the same time, scaling of volatile SRAM is slowing down due to the cell footprint (# of F2) degradation occurring at advance nodes, so that a denser working embedded memory would be highly desirable.

STT-MRAM combines the attributes of conventional memory types in a single technology. Virtually, it features the speed of SRAM and the non-volatility of eFlash with unlimited endurance, it can be added to process flows for logic chips without significant cost increase, offering a remarkable density gain over SRAM together with very low power consumption. These features are ideal for a variety of applications, including IoT/wearables, microcontrollers (MCU), automotive chips, artificial intelligence, and more.

GlobalFoundries is pioneer in embedded memory technologies and has been working for years to solve integration challenges, enabling the integration of embedded STT-MRAM in their 22nm FDSOI technology platform.

Yole is following the memory industry for a while with a wide collection of dedicated monitors and reports. Emerging Non-Volatile Memory report and MRAM Technology & Business report* are part of it. Both technology & market studies reveal the status of the memory industry, point out technical innovations and analyze competitive landscape. To present these key results and explain its vision of the memory industry evolution, Yole is organizing an Executives Breakfast, prior the Flash Memory Summit. This Yole’s Event will take place on August 6, from 7:00 to 9:30. Make sure to discover the program right now and register today!

In addition, Yole Développement (Yole) had the opportunity to meet Martin Mason, Senior Director of Embedded Memory at GlobalFoundries to discuss the company’s view on embedded MRAM, the technology status and roadmap for the coming years. This interview has been conducted by Simone Bertolazzi, PhD., Market & Technology Analyst, Memory at Yole.

Simone Bertolazzi (SB): The proliferation of Internet of Things (IoT) devices and automotive electronics is driving the continuous growth of the embedded memory market. However, mainstream technologies – such as eFlash and SRAM – are facing significant scaling challenges and power-consumption issues. In this context, what is the position and strategy of GlobalFoundries?

Martin Mason (MM): Emerging NVM technologies are successfully addressing the technical requirements such as higher memory density, low power consumption, and high performance that are critical to new application drivers such as IoT and automotive electronics. In addition, the major fab equipment vendors began investing in the development of mass production equipment specifically for emerging NVM, and the appearance of these new tools mean that emerging NVM is now also a sufficiently cost effective solution for customers.

GlobalFoundries has a unique capability of putting a NOR-flash replacement eMRAM macro on a die. These pre-built and verified eMRAM macros can be dropped into 22FDX designs. There are now 32- and 16- Mbit macros built with a single magnetic tunnel junction (MTJ) bit cell and a NOR flash-type interface with a 4-Mbit macro is planned for the first half of 2019.

A number of customers use more than one macro in their designs. Using MRAM may not give much of a density savings compared with SRAM at 22nm, but they told us ‘that doesn’t matter, it is really about power.’ In many of these portable applications, power is what is critical. Clients really love to exploit the persistence for the power savings inside the chip, having the ability to be completely static, support fast start-up from power down and retain data values.

SB: What is GlobalFoundries’ current embedded-memory portfolio?

MM: GF’s technology platforms from 130nm to 22nm offer a wide variety of embedded memory solutions to address the emerging markets. These include embedded magneto-resistive RAM (eMRAM), embedded Flash (eFlash) and System In Package (SIP Flash) to address the requirements of broad market segments.

GlobalFoundries’ eMRAM offering, with its low power consumption, is ideal for the MCU and IoT markets, especially when combined with the 22nm 22FDX FD-SOI platform. Its fast write speed, high endurance and high memory capacity makes it suitable for compute and storage markets. The company’s eFlash solutions, along with RF and analog enablement and comprehensive IP, are optimized for specific applications such as wearables, IoT, automotive, industrial, and consumer. SIP Flash is a flexible and cost-effective package based solution for low cost, high capacity memory requirements. It delivers the fastest time to market, using qualified, off-the-shelf NOR flash memory and is ideal for consumer and AR/VR applications.

Since eMRAM integrates well with both FD-SOI and FinFET, we expect eMRAM to become available on 14/12nm FinFET as well as next-generation FDX™ technology

SB: In 2017, GlobalFoundries announced the availability of embedded MRAM (eMRAM) on its 22-nm FD-SOI process (22FDX®). Could you please describe to our readers the activities of GlobalFoundries in the emerging NVM business?

MM: There is a critical industry pivot underway to new NVM memories and silicon on insulator technologies.

We are seeing a strong interest in eMRAM from our customers, especially with FD-SOI which brings together best-in-class capabilities. The power efficiency of FDX™ and eMRAM, coupled with the available RF connectivity and mmWave IP, makes 22FDX an ideal platform for battery-powered IoT, edge AI, and autonomous vehicle radar system-on-chips (SoCs).

Process design kits for GF’s 22nm FD-SOI (22FDX) eMRAM macros are available now. And, customer prototyping is underway, with our first silicon tape out from a large European, IoT customer. Multiple production tape outs are scheduled for 2019.

SB: Nowadays, the major foundries are all getting ready with 28/22 nm technology processes based on eMRAM or eRRAM. What are the main reasons behind such a growth of momentum for emerging NVM?

MM: eMRAM has the greatest versatility of all the memory types, with superior performance and reliability. However, eMRAM is a complex technology to master, and requires a significant investment to develop and deploy.

RRAM is also being developed as a simpler, lower cost option, and competes directly with eFlash at the 40nm node. Moreover, 28nm is the last cost-effective node for eFlash, and the transition to 22nm is what is driving an eFLASH replacement for data storage/configuration memory. The relative lack of maturity of RRAM especially on the 2x process nodes has been limiting its adoption as a mainstream memory technology.

SB: What are the first applications that will benefit from GlobalFoundries’ eMRAM?

MM: GlobalFoundries 22FDX eMRAM targets connected IoT, GP-MCU, automotive and edge AI applications. We expect adoption across all those markets, in the order given.

eMRAM Memory - Courtesy of GlobalFoundries, 2019
eMRAM Memory – Courtesy of GlobalFoundries, 2019

SB: When do you expect the first eMRAM-based MCUs will enter the automotive market? What are the main technical challenges in reaching this goal?

MM: In 1H 2021 we anticipate the first Auto Grade 1 MRAM solutions to be available. Having a robust bit cell that can achieve extended temperature support with low bit error rate will be the major challenge for automotive grade-1 MRAM technology.

SB: Emerging NVM (eNVM) is gaining attention as manufacturing costs decrease and other memory technologies face scalability challenges. What is the potential for eNVM in replacing eFlash, or even SRAM? When do you think this could happen?

MM: Embedded flash will have a long life with the data retention in harsh environments, but it becomes an expensive option especially when it scales to 28nm or below. For code/data storage, in leading edge processes, eMRAM technology will be used as a flash replacement starting at the end of 2019 with the GlobalFoundries’ eMRAM-F solution on 22FDX. The economics for MRAM-S as a working memory augmenting SRAM make most economic sense at the 1x node(s). It has been recently reported that 4 major foundries (including GF) will support eMRAM production at 28/22nm, but not all of the eMRAM deployed at 22nm will be flash like in its specifications.

SB: Among the different eNVM technologies currently under development, why did GlobalFoundries decide to focus particularly on eMRAM? What are the pros/cons of eMRAM compared to other emerging memories?

MM: MRAM can do two jobs: it can do code storage which offers lower energy write  saving some power and, since MRAM has very high endurance, it can be used for working memory. You can get some improvement for substituting MRAM for eFlash in architecture for the code storage. Uniquely eMRAM can also replace SRAM as a working memory so the technology can address two application needs.

SB: What differentiates your embedded memory technology from those of the other major foundries?  

MM: GF’s 22nm process with eMRAM is unique because we are on our third generation MRAM technology having had the added experience of mass producing the Everspin 256Mb and 1Gb standalone MRAM products as part of our joint development agreement. We have demonstrated high temperature performance for eMRAM, to reassure the auto makers and industrial MCU makers that it will be a viable solution for their pending need for new embedded memory technology, which must retain data at high temperature, including through solder reflow (260°C).

SB: What is your point of view on the overall eMRAM ecosystem? Do you think further developments are necessary toward the mass adoption of eMRAM?

MM: In general, the eco-system is generally well developed to support the design in and deployment of MRAM based devices.  Key to eFLASH replacement is GlobalFoundries’ MRAM solution that is robust and the most eFLASH-like MRAM solution in its features and specifications. Additionally, there are always areas for improvement; MRAM compilers and MBIST technology are some of the areas where both the Foundries and ODMs could benefit from further investment. Furthermore, MRAM compilers and MRAM device test knowledge are two areas that would accelerate broad MRAM adoption in general.

SB: What will be the next moves of GlobalFoundries in the embedded memory business?

MM: GlobalFoundries is working with many customers, running multi-project wafers (MPWs) with eMRAM on 22FDX®-based designs. Embedded MRAM has passed multiple (five times) solder reflow tests, and exhibits extended data retention and endurance at extended temperatures. It has “very comparable” read speed and much faster (order of magnitude) write speed (200 nanoseconds compared to 20 microseconds) than eFlash memories.

Customers will be evaluating GF’s 22FDX process with MRAM for their next-generation IoT (MCU) designs to take advantage of these new technologies.

Multiple production tape outs are scheduled for 2019.

Interviewee:

Martin Mason is the Sr. Director Business Management for Advanced Node Embedded Non Volatile Memory technology at GlobalFoundries in Santa Clara California. Martin has over 25 years of semiconductor business management experience in FPGAs, mixed signal, and embedded memory technologies. He has a degree in Microelectronics from the University of Newcastle –upon-Tyne in the UK and holds a dozen US patents.

Interviewer:

Simone Bertolazzi, PhD is a Technology & Market analyst at Yole Développement (Yole) working with the Semiconductor & Software division. He is member of the Yole’s memory team and he contributes on a day-to-day basis to the analysis of memory technologies, their related materials and fabrication processes. Simone obtained a PhD in physics in 2015 from École Polytechnique Fédérale de Lausanne (Switzerland), where he developed novel flash memory cells based on heterostructures of two-dimensional materials and high-κ dielectrics.

Related reports:

*MRAM Technology & Business 2019

This report will be available in August 2019 – For more information, contact us

Emerging Non-Volatile Memory 2018

After more than 15 years in development, PCM has finally taken off in stand-alone applications. STT-MRAM will lead the embedded memory race.

Source: http://www.yole.fr, http://www.globalfoundries.com

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