NAND-like ‘3D X-DRAM’ Aimed to Revolutionize the Memory Industry

One of the prominent trends in the DRAM industry is the push for higher memory capabilities. With the rise of data-intensive applications such as artificial intelligence, big data analytics, and cloud computing, there is a growing demand for high memory densities to accommodate the processing requirements of these applications. Researchers and engineers are developing smaller process nodes and improved chip-stacking techniques to integrate more memory cells into a single chip.

 

The projected future of DRAM technology, according to Neo Semiconductor. Image courtesy of Neo Semiconductor

 

Neo Semiconductor, a company focused on 3D NAND flash memory and other memory technologies, recently launched the world's first NAND-like DRAM to solve DRAM's capacity bottleneck and replace 2D DRAMs in high memory density applications. 

 

DRAM Capacity Bottleneck

The term "DRAM capacity bottleneck" refers to the limit on how much memory can be stored in one DRAM chip—dependent on the physical size of the DRAM and the number of memory cells in it. The memory cell density is limited by the size of the cells, the thickness of the layers used to build the chip, and the amount of power required to operate the chip.

Memory-intensive applications associated with AI have put pressure on DRAM manufacturers to increase the capacity of their chips. While the size of DRAM chips has been decreasing over the years, the rate of miniaturization has slowed down due to several technical challenges. Namely, since 2016, DRAM sizes have stalled at 10 nm because of capacitor sizes and other electrical limitations below the 10 nm level. 

 

Neo Semiconductor's 3D X-DRAM Technology

Despite this scaling challenge, Neo Semiconductor has found another way to increase memory density by developing the world's first 3D NAND-like DRAM cell array, called 3D X-DRAM. The company applied for a patent with the United States Patent Application Publication last week.

The new cell array structure is based on Neo Semiconductor's capacitor-less floating body cell technology. This structure instead stores data in the form of electric charges without capacitors. It is "NAND-like" in its use of a 3D architecture to increase storage capacity, but it differs in its underlying technology, intended use cases, and performance characteristics. Like NAND, the 3D X-DRAM vertically stacks memory cells to increase storage capacity without increasing the physical footprint of the memory chip.

The 3D X-DRAM architecture incorporates a unique read/write mechanism for faster access times and lower latency than NAND flash.

 

The concept of 3D X-DRAM. Image courtesy of Neo Semiconductor

 

Beyond high memory density, the new DRAM technology offers several other advantages over conventional DRAM, including lower power consumption, high reliability, improved scalability, and faster access times due to shorter interconnects between memory cells.

The new DRAM cells can be manufactured using the current 3D NAND-like process and only needs a single mask to define the bit line holes and form the cell structure inside the holes, simplifying the process. Based on company estimates, this technology can achieve 128 Gb density with 230 layers—eight times today's DRAM density.