- Kioxia develops high-density 3D DRAM using stackable oxide semiconductor transistors
- Eight-layer transistor stack shows reliable operation in laboratory demonstrations
- Oxide semiconductor InGaZnO replaces silicon nitride for vertical and horizontal transistor formation
Kioxia says it has developed highly stackable oxide semiconductor channel transistors capable of supporting high-density 3D DRAM.
This development could lead to cheaper and faster memory by lowering production costs per unit. gigabytes and improve energy efficiency through high-current and ultra-low-current zero-current transistors.
However, this technology requires precise multilayer alignment, integration into standard manufacturing, and long-term reliability testing, all of which can take decades.
Innovations in transistor design
Presented at the recent IEEE International Electron Devices Meeting in San Francisco, the technology demonstrated the operation of transistors stacked in eight vertical layers.
The vertical layers consist of horizontally aligned transistors formed by replacing conventional silicon nitride areas with an oxide semiconductor material, InGaZnO.
This arrangement allows for increased memory capacity without relying on conventional planar DRAM structures.
The oxide semiconductor channel transistors combine mature silicon oxide and silicon nitride films with the new InGaZnO material.
The 3D memory cell structure introduced by Kioxia scales the vertical pitch so that more memory cells can be stacked per volume unit.
The horizontal transistors formed in this process exhibit high on-current of more than 30 microamps.
It also features ultra-low off-current below 1 attoamp, minimizing power consumption during refresh cycles.
By reducing refresh power, the design addresses a major limitation of traditional DRAM, where power consumption increases with higher memory densities.
Replacing single crystal silicon with oxide semiconductors reduces both complexity and energy requirements in manufacturing.
These improvements lower the cost of manufacturing DRAM per gigabytes, although retail prices for end users are not expected to decrease in the near term.
The stacked transistor approach also targets applications that require high memory density with low power consumption, such as AI servers and IoT devices.
The increased efficiency could support processing of larger data sets without the same proportional increase in energy demand seen in conventional DRAM systems.
Despite these technical advances, the transition of the technology from laboratory demonstrations to mass production presents significant challenges.
Aligning multiple layers precisely, integrating oxide semiconductor materials into standard production lines, and ensuring long-term reliability remain obstacles to commercialization.
The company plans to continue research and development to enable the practical implementation of 3D DRAM in real-world applications.
Although the technology shows clear technical advantages in energy efficiency, density and manufacturing feasibility, it is unlikely to reach consumer markets until the next decade.
That being said, cheaper manufacturing per gigabytes not lower retail prices, and large-scale adoption will require overcoming both manufacturing and supply chain issues.
Via TechPowerUp
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