RTC will present three technical papers at VLSI symposium 2023

The three papers are about 3D Ferroelectric NAND Flash, Crystalline IGZO transistors, and four-deck 3DXP memory. Their titles are ①“The QLC Programmable 3D Ferroelectric NAND Flash Memory by Memory Window Expansion using Cell Stack Engineering”, ②“Demonstration of crystalline IGZO transistor with high thermal stability for memory applications”, and ③“The chalcogenide-based memory technology continues: beyond 20nm 4-deck 256Gb cross-point memory”.

In the first paper, the world’s first QLC programmable 3D NAND Flash is introduced. It shows the possibility of Ferroelectric 3D NAND Flash to overcome the vertical scale limit of cell-to-cell interference in the conventional CTN (Charge Trap Nitride) based 3D NAND Flash.

In the second paper, the feasibility of IGZO transistors with highly ordered crystalline InGaZnO (c-IGZO) is examined. Owing to the well-controlled crystalline structure, the device can be processed above 550 °C and is immune to the hydrogen atmosphere to show the higher on current (Ion) than the amorphous IGZO.

The third paper is about the well-known 3DXP memory device. While our previous paper (IEDM 2018) is about 2znm two-deck technology for 128Gb, this time we demonstrated the 20nm four-deck technology for 256Gb. We showed not only the maturity of four-deck technology for mass production, but also discuss the lateral scaling limit of conventional 3DXP devices. In the end, we strongly suggest the possible extension of 3DXP by changing gears to the SOM (Selector Only Memory) and ultimately to the VXP (Vertical Cross Point).

In addition, Dr. Myung-Hee Na from RTC will also participate in the renowned VLSI panel discussion as a panelist this year. The topic of the “What’s Scalable & Sustainable in the Next 25 years?”