Home Technology UltraRAM: RAM mass storage symbiosis is getting closer to series production

UltraRAM: RAM mass storage symbiosis is getting closer to series production

UltraRAM: RAM-Massenspeicher-Symbiose rückt Serie näher

Image: Pixabay UltraRAM is the name of a new technical approach in the search for a universal memory that takes over the tasks of working memory and mass storage at the same time. Now researchers report a breakthrough on the way to mass production of UltraRAM. A year ago, researchers at Lancaster University in the UK presented their UltraRAM. The technology is a new form of non-volatile random access memory (NVRAM), which, like mass storage, keeps the data permanently even without a power supply. Like RAM, it should be fast and survive many write cycles, like NAND flash it should be non-volatile. The technique has been described as “a compound semiconductor charge storage device that uses quantum phenomena for its operational advantages”. The so-called III-V compound semiconductors are also used to manufacture lasers, light-emitting diodes and solar cells.

How UltraRAM works

UltraRAM uses Indium Arsenide (InAs) quantum wells and Aluminum Antimonide (AlSb) barriers to create what is known as a Triple Barrier Resonant Tunneling (TBRT) structure. The stored information is represented by the presence or absence of electrons in a floating gate (FG). When a low voltage (~2.5 volts) is applied, the structure becomes permeable to electrons. “By using the TBRT heterostructure as a barrier between the FG and the channel instead of the usual monolithic material, a charge-based memory with exceptional properties can be achieved,” the paper, published in early January, states.

  • UltraRAM memory cell concept (Image: Lancaster University)

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    Captured on silicon wafers closer to the market launch

    The most recent “breakthrough” on the way to the commercialization of the technology is its implementation on a silicon carrier (Si substrate). This is “an important step towards cost-effective mass production”. The technique had previously been tested on gallium arsenide (GaAs) wafers, which are far more expensive to manufacture.

    Durability significantly better than NAND flash

    When it comes to durability and data retention, UltraRAM should have a clear advantage over NAND flash. In tests, 10 million write and erase cycles (program/erase cycles) have already been achieved, but this is only the minimum for the time being. With NAND flash, 1 million P/E cycles (with earlier SLC NAND) is already considered a lot. Today’s dominant TLC-NAND is estimated to be well below 10,000 P/E cycles. The researchers can only extrapolate the data retention of UltraRAM, but they come up with over 1,000 years.

    Performance could surpass DRAM

    In terms of performance, which is determined by the duration for switching the states in the memory cells, ≤10 ms is already fast for a circuit with a relatively large structure width (20 µm feature size). With finer production and correspondingly perfect scaling of the performance, even the switching speed (switching speed) of DRAM can be exceeded, according to the researchers. However, this still needs to be put to the test.

    Assuming ideal capacitive scaling down to state-of-the-art feature sizes, the switching performance would be faster than DRAM, although testing on smaller feature size devices is required to confirm this.

    Low power to switch

    The energy required for switching should be 100 or 1000 times lower with UltraRAM than with DRAM or NAND flash. So there is also great potential in energy efficiency.

    Now it’s time to wait

    Many factors, most notably the cost of manufacturing per bit of storage capacity, will determine whether UltraRAM will reach the market as a new universal memory that effectively combines RAM and storage. For the researchers, it is now a matter of fine-tuning the technology and the manufacturing process.

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