Interface engineering of 9X stacked 3D NAND flash memory using hydrogen post-treatment annealing.

This study investigates the effects of hydrogen post-treatment on 3D NAND flash memory. Hydrogen post-treatment annealing (PTA) is suggested to passivate the defects in the tunneling oxide/poly-Si interface and inside the poly-Si channel. However, excess hydrogen PTA can release hydrogen atoms from the passivated defects, which may degrade device performance. Therefore, it is important to determine the appropriate PTA condition for optimization of the device performance. Three different conditions for hydrogen PTA, namely Reference, H, and H++, are applied to observe the effects on device performance. The activation energy (Ea) of the device parameters was extracted according to the hydrogen PTA condition to analyze the effects. The extractedEais about 74 meV for Reference, 53 meV for H, and 58 meV for H++conditions, with the best performance observed at the H condition. Optimal hydrogen PTA shows the best on-current (51% higher than Reference) and stable short-term retention (66% suppressedΔVTthan Reference) in 9X stacked 3D NAND flash memory.

Influence of flexible substrate in low temperature polycrystalline silicon thin-film transistors: temperature dependent characteristics and low frequency noise analysis.

The carrier transport of p-type low temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) on flexible substrate has been intensively studied and compared to that on glass substrate in order to improve device performance. To investigate the origin of carrier transport on different substrates, temperature dependent characterizations are carried out for electrical device parameters such as threshold voltage (V TH ), subthreshold swing (SS), on-current (I on ) and effective carrier mobility (µeff ). The poly-Si grain size L grain and the barrier height E B between grain boundaries are well known to be the main parameters to determine transport in polycrystalline silicon and can be extracted based on the polycrystalline mobility model. However, our systemic studies show that it is not grain size but E B that has more influence on the degradation of LTPS TFT on flexible substrates. The E B of flexible substrate is roughly 18 times higher than glass substrate whereas grain size is similar for both devices on different substrates. Compared to the LTPS TFT on glass substrate, higher E B degrades approximately 24 % of Ion , 30 % of SS and 21 % of µ eff on the flexible substrate at room temperature. From low frequency noise (LFN) analysis, it is observed that the total trap density (N t) for flexible substrate is up to four times higher than that of glass substrate, which also supports the high value of EB in the device fabricated on the flexible substrate.