- The company has developed a new memory architecture for NAND based flash devices
- This technology can pack flash memory designs with higher memory density and fewer stacking layers
Flash memory technology has evolved into a preferred media storage device for a variety of consumer and industrial devices. 3D flash memory technology achieves high bit density while decreasing the bit costs. This results in an increased number of stacked layers of a cell. It uses a multi-layer stack deposition technique to achieve stacked architecture.
Claimed to be the first three-dimensional flash memory structure
Kioxia Corporation has claimed to develop the world’s first three-dimensional semicircular split-gate flash memory cell structure. It features twin BiCS made by using floating gate (FG) cells. The fabrication of these BICS includes the cutting of floating gates in half. This increases the total capacity of the memory cell.
The twin BiCS flash thus achieves superior program slope and a larger program/erase window. It features all these functions at a much smaller cell size compared to conventional circular charge trap (CT) cells. The company claims that this design attribute also helps the device to surpass four bits per cell (QLC). It helps produce higher memory density and fewer stacking layers.
The curvature effect
According to Kioxia, the circular control gate provides a larger program window with relaxed saturation problems when compared with a planar gate. It is due to the curvature effect. It is a phenomenon when carrier injection through the tunnel dielectric is enhanced while electron leakage to the block (BLK) dielectric is lowered.
Proof of concept published
In this split-gate cell design, the circular control gate is symmetrically divided into two semicircular gates. Dividing these gates increases the performance of the program/erase dynamics.
On this latest research, the company has also published an image describing “How the conductive storage layer is employed for high charge trapping efficiency in conjunction with the high-k BLK dielectrics “.
Kioxia says its research and development in flash memory will include continuing twin BiCS flash development and seeking its practical applications.