Contour Semiconductor is developing a new non-volatile memory that leverages Phase Change Memory (PCM) technology and some other innovations to simplify the design process and provide better performance and endurance.
Diode Transistor Memory
Contour’s Diode Transistor Memory (DTM) technology uses diodes instead of transistors as the way to preserve the digital state (the ‘select device’), producing an alternative to traditional NAND flash in solid state memory devices. Using diodes, which are a two-conductor device, produces a memory substrate that’s more compact than three-conductor transistors and less expensive to manufacture. According to Contour, their fabrication process involves 15 mask layers instead of 35, which is typical with NAND flash fabrication. Fewer process steps means fewer possible defects and lower tooling and other fabrication costs. The company claims the DTM process can reduce wafer production costs by 65% and improve fab capacity by 3x.
Phase Change Memory
Flash memory stores a bit by modulating the charge on a semiconductor layer in a transistor, with a digital “0” being represented by a low voltage and a “1” by a higher voltage. PCM materials store bits by switching between a disordered, “amorphous” state and an ordered, “crystalline” state in response to an electrical pulse. Each state or “phase” presents a different resistance. PCM can switch between these two states much faster than NAND flash, up to 1000x faster, producing better performance.
DTM requires 70% less reset current, meaning it consumes less energy in operation, producing better endurance without wear leveling. DTM also offers a more granular data access, enabling the device to write data in smaller blocks, improving overall efficiency in the write process and reducing data handling overhead typical in flash controllers.
PCM is a promising technology in the non-volatile memory space. It’s much faster and has better longevity than NAND flash but its cost and density have been drawbacks. Contour’s DTM may help it on both fronts, making this technology cost-effective for more use cases, sooner.