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In2Ga2ZnO7 oxide semiconductor based charge trap device for NAND flash memory.
Eun Suk Hwang1, Jun Shik Kim1, Seok Min Jeon1
1Department of Materials Science & Engineering, and Inter-University Semiconductor Research Center, Seoul National University, Seoul, 151-744, Republic of Korea.
Nanotechnology
|February 9, 2018
Summary
Metal-organic chemical vapor deposition (MOCVD) grown amorphous Indium Gallium Zinc Oxide (a-IGZO) exhibits faster programming speeds in charge trap flash memory. This enhanced performance is linked to a higher Fermi level in MOCVD-deposited a-IGZO films.
Area of Science:
- Materials Science
- Electrical Engineering
- Semiconductor Physics
Background:
- Charge trap flash memory devices are crucial for data storage.
- Amorphous Indium Gallium Zinc Oxide (a-IGZO) is a promising channel material for these devices.
- Optimizing the programming characteristics of a-IGZO based flash memory is essential for improved performance.
Purpose of the Study:
- To evaluate the programming characteristics of charge trap flash memory devices utilizing a-IGZO.
- To compare the performance of a-IGZO films grown by Metal-Organic Chemical Vapor Deposition (MOCVD) and RF-sputtering.
- To identify the underlying physical mechanisms responsible for differences in programming speed.
Main Methods:
- Fabrication of charge trap flash memory devices with a-IGZO channel layers using MOCVD and RF-sputtering.
- Characterization of a-IGZO films, including stoichiometry, oxygen vacancies (via X-ray photoelectron spectroscopy and bias-illumination-instability tests), and Fermi level (via Ultraviolet Photoelectron Spectroscopy).
- Evaluation of device programming speeds.
Main Results:
- Both MOCVD and sputtered a-IGZO films exhibited comparable stoichiometry and oxygen vacancy concentrations.
- MOCVD-grown a-IGZO demonstrated significantly faster programming speeds compared to sputtered a-IGZO.
- Ultraviolet Photoelectron Spectroscopy revealed a higher Fermi level (EF ≈ 0.3 eV) in MOCVD a-IGZO, attributed to higher hydrogen concentration.
Conclusions:
- The higher Fermi level in MOCVD-grown a-IGZO is the primary factor contributing to its faster programming speed.
- Hydrogen concentration plays a significant role in tuning the electronic properties and performance of a-IGZO in flash memory devices.
- MOCVD presents a viable method for fabricating high-performance a-IGZO channel layers for advanced flash memory applications.
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