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Reliable And Efficient Compact Models For Scalable MTJ Simulation


By Fernando García Redondo, Pranay Prabhat, and Mudit Bhargava Since its discovery in 1975, Tunnel-Magneto-Resistance (TMR) has been actively investigated. From the 2000s, advances in process technologies have made the miniaturization of Magnetic Random Access Memories (MRAMs) based on TMR devices possible, together with integration into traditional CMOS processes. Introducing magneti... » read more

New Memories Add New Faults


New non-volatile memories (NVM) bring new opportunities for changing how we use memory in systems-on-chip (SoCs), but they also add new challenges for making sure they will work as expected. These new memory types – primarily MRAM and ReRAM – rely on unique physical phenomena for storing data. That means that new test sequences and fault models may be needed before they can be released t... » read more

Convolutional Compaction-Based MRAM Fault Diagnosis


Abstract: "Spin-transfer torque magnetoresistive random-access memories (STT-MRAMs) are gradually superseding conventional SRAMs as last-level cache in System-on-Chip designs. Their manufacturing process includes trimming a reference resistance in STT-MRAM modules to reliably determine the logic values of 0 and 1 during read operations. Typically, an on-chip trimming routine consists of mult... » read more

MBIST-supported Trim Adjustment to Compensate Thermal Behavior of MRAM


Abstract: "Spin Transfer Torque Magnetic Random Access Memory (STT-MRAM) is one of the most promising candidates to replace conventional embedded memory such as Static RAM and Dynamic RAM. However, due to the small on/off ratio of MRAM cells, process variations may reduce the operating margin of a chip. Reference trimming was suggested as one of the ways to reduce variation impact to the chi... » read more

A Compact Model For Scalable MTJ Simulation


Read the full technical paper. Published June 9, 2021. Abstract This paper presents a physics-based modeling framework for the analysis and transient simulation of circuits containing Spin-Transfer Torque (STT) Magnetic Tunnel Junction (MTJ) devices. The framework provides the tools to analyze the stochastic behavior of MTJs and to generate Verilog-A compact models for their simulation in lar... » read more

A Novel Memory Test System With An Electromagnet For STT-MRAM Testing


We have successfully developed, for the first time, a new memory test system for STT-MRAM at wafer-level where an electromagnet is combined with a memory test system and a 300 mm wafer prober. In the developed memory test system, an out-of-plane magnetic field up to ±800 mT can be applied on 10 x 10 mm2 in the 300 mm wafer with distribution of less than 2.5%. We demonstrated that the electroma... » read more

MRAM Evolves In Multiple Directions


Magnetoresistive RAM (MRAM) is one of several new non-volatile memory technologies targeting broad commercial availability, but designing MRAM into chips and systems isn't as simple as adding other types of memory. MRAM isn’t an all-things-for-all-applications technology. It needs to be tuned for its intended purpose. MRAMs targeting flash will not do as well targeting SRAMs, and vice vers... » read more

Manufacturing Bits: Feb. 2


Capacitor-less DRAM At the recent 2020 International Electron Devices Meeting (IEDM), Imec presented a paper on a novel capacitor-less DRAM cell architecture. DRAM is used for main memory in systems, and today’s most advanced devices are based on roughly 18nm to 15nm processes. The physical limit for DRAM is somewhere around 10nm. DRAM itself is based on a one-transistor, one-capacito... » read more

More Data, More Memory-Scaling Problems


Memories of all types are facing pressures as demands grow for greater capacity, lower cost, faster speeds, and lower power to handle the onslaught of new data being generated daily. Whether it's well-established memory types or novel approaches, continued work is required to keep scaling moving forward as our need for memory grows at an accelerating pace. “Data is the new economy of this ... » read more

DRAM, 3D NAND Face New Challenges


It’s been a topsy-turvy period for the memory market, and it's not over. So far in 2020, demand has been slightly better than expected for the two main memory types — 3D NAND and DRAM. But now there is some uncertainty in the market amid a slowdown, inventory issues and an ongoing trade war. In addition, the 3D NAND market is moving toward a new technology generation, but some are enc... » read more

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