Comparative Analysis of Bandgap-Engineered Pillar Type Flash Memory with HfO2 and S3N4 as Trapping Layer

Sang-Youl LEE  Seung-Dong YANG  Jae-Sub OH  Ho-Jin YUN  Kwang-Seok JEONG  Yu-Mi KIM  Hi-Deok LEE  Ga-Won LEE  

IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.5   pp.831-836
Publication Date: 2012/05/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.831
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
SOHOS,  high-k,  gate-all-around,  program/erase speed,  flash memory,  

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In this paper, we fabricated a gate-all-around bandgap-engineered (BE) silicon-oxide-nitride-oxide-silicon (SONOS) and silicon-oxide-high-k-oxide-silicon (SOHOS) flash memory device with a vertical silicon pillar type structure for a potential solution to scaling down. Silicon nitride (Si3N4) and hafnium oxide (HfO2) were used as trapping layers in the SONOS and SOHOS devices, respectively. The BE-SOHOS device has better electrical characteristics such as a lower threshold voltage (VTH) of 0.16 V, a higher gm.max of 0.593 µA/V and on/off current ratio of 5.76108, than the BE-SONOS device. The memory characteristics of the BE-SONOS device, such as program/erase speed (P/E speed), endurance, and data retention, were compared with those of the BE-SOHOS device. The measured data show that the BE-SONOS device has good memory characteristics, such as program speed and data retention. Compared with the BE-SONOS device, the erase speed is enhanced about five times in BE-SOHOS, while the program speed and data retention characteristic are slightly worse, which can be explained via the many interface traps between the trapping layer and the tunneling oxide.