Using an ammonia treatment to improve the floating-gate spacing in split-gate flash memory

In the split-gate flash memory process, during poly oxidation, the bird's beak encroaches under the SiN film, especially along the poly grain boundary, and that will cause nonuniform floating-gate (FG) spacing, even bridging, which is an obstacle to cell shrinkage. We show that employing an amm...

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Bibliographic Details
Published in:IEEE electron device letters 2004-09, Vol.25 (9), p.616-618
Main Authors: Wen-Ting Chu, Hao-Hsiung Lin, Yeur-Luen Tu, Yu-Hsiung Wang, Chia-Ta Hsieh, Hung-Cheng Sung, Yung-Tao Lin, Chia-Shiung Tsai, Wang, C.S.
Format: Article
Language:English
Subjects:
Ammonia
Applied sciences
Bridging
Character generation
CMOS technology
Devices
Electronics
EPROM
Exact sciences and technology
Flash memory
Flash memory (computers)
Grain boundaries
Integrated circuits
Integrated circuits by function (including memories and processors)
Nonuniform
Nonvolatile memory
Oxidation
Oxynitrides
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
Silicon compounds
Split gate flash memory cells
Surface treatment
X-ray photoelectron spectroscopy
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Summary:In the split-gate flash memory process, during poly oxidation, the bird's beak encroaches under the SiN film, especially along the poly grain boundary, and that will cause nonuniform floating-gate (FG) spacing, even bridging, which is an obstacle to cell shrinkage. We show that employing an ammonia treatment on the poly can nitridize the poly surface, thereby avoiding bird's beak bridging. After the ammonia treatment, FG spacing is quite uniform and can be improved from 0.09 to 0.03 μm. The XPS analysis on the ammonia treated poly shows the oxynitride thickness is less than 5 nm.
ISSN:0741-3106
1558-0563
DOI:10.1109/LED.2004.833825