Saturday, January 6, 2018

New ALD High-k / 2D MoS2 light-erasable memory suitable for large area manufacturing technology

Phys.Org reports that researchers at the Institute of Microelectronics Chinese Academy of Sciences (IMECAS), and Fudan University have used 2D MoS2 to design a new light-erasable memory.

According to the article in Applied Physics Letter, the memory stack is based on an high-k dielectric stack (Al2O3/HfO2/Al2O3) and an atomically thin MoS2 channel, where he HfO2 act as the charge trapping layer. The holes in the HfO2 charge-trapping layer will tunnel to the MoS2 channel through the 4 nm Al2O3 tunnel layer. 
Schematic band diagrams of the MoS2/Al2O3/HfO2/Al2O3/Gate structure at (a) flat-band condition, (b) programming operation, and (c) erasing operation. (Supplementary information, Applied Physics Letters. DOI: 10.1063/1.5000552)

"In general, system-on-panel (SOP) describes a new display technology in which both active and passive components are integrated in one panel package, typically on the same glass substrate (sometimes system-on-panel is also named system-on-glass)," coauthor Hao Zhu at Fudan University told "This is different from traditional display technologies such as cathode ray tube (CRT) displays. One major characteristic of SOP is the application of thin-film technology, such as low-temperature poly-silicon (LTPS) thin-film transistor (TFT) arrays on the glass substrate. However, silicon-based thin-film transistors are being replaced by TFTs with new materials with improved properties. The indium gallium zinc oxide (IGZO) or zinc tin oxide (ZTO) thin film mentioned in our paper is also a good example. []

"Currently, we are working on the large-scale integration of such light-erasable 2-D memory devices using programmable light pulses with controllable wavelength and pulse duration," he said. "We are using new material synthesis methods such as atomic layer deposition to grow large-area MoS2 and other 2-D ultra-thin films for circuit-level applications." 

The future prospects for large scale manufacturing are there. Except for the MoS2 channel, both Al2O3 and HfO2 are standard ALD processing technologies since more than 10 years in the semiconductor industry and recent developments for flexible OLED Display manufacturing  has made the ALD technology also available for large panel processing and roll to roll technology is just looking for an excuse high volume manufacturing.
Article: Long-Fei He et al. "Light-erasable embedded charge-trapping memory based on MoS2 for system-on-panel applications." Applied Physics Letters. DOI: 10.1063/1.5000552

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