Imaging Of Overlay And Alignment Markers Under Opaque Layers Using Picosecond Laser Acoustic Measurements


Optically opaque materials present a series of challenges for alignment and overlay in the semi-damascene process flow or after the processing of the magnetic tunnel junction (MTJ) of a Magnetic Random-Access Memory (MRAM). The overlay and alignment of a lithographically defined pattern on top of the pattern and the underlying layer is fundamental to device operation in all multi-layer patterne... » read more

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

HBM Takes On A Much Bigger Role


High-bandwidth memory is getting faster and showing up in more designs, but this stacked DRAM technology may play a much bigger role as a gateway for both chiplet-based SoCs and true 3D designs. HBM increasingly is being viewed as a way of pushing heterogenous distributed processing to a completely different level. Once viewed as an expensive technology that only could be utilized in the hig... » read more

Domain-Specific Memory


Domain-specific computing may be all the rage, but it is avoiding the real problem. The bigger concern is the memories that throttle processor performance, consume more power, and take up the most chip area. Memories need to break free from the rigid structures preferred by existing software. When algorithms and memory are designed together, improvements in performance are significant and pr... » 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

Shared-Write-Channel-Based Device for High-Density Spin-Orbit-Torque Magnetic Random-Access Memory


ABSTRACT "Spin-orbit-torque (SOT) devices are promising candidates for the future magnetic memory landscape, as they promise high endurance, low read disturbance, and low read error, in comparison with spin-transfer torque devices. However, SOT memories are area intensive due to the requirement for two access transistors per bit. Here, we report a multibit SOT cell that has a single write chan... » read more

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