Effect of heavy inert ion strikes on cell density-dependent profile variation and distortion during the etching process for high-aspect ratio features

Vertical scaling technique faces a physical limitation in 3D NAND device fabrication, even assuming superior etching technology. Another promising scaling technique to increase the storage density is lateral scaling, which increases the number of holes between slit and slit from four to nine and above. However, unpredictable small critical dimension, feature-to-feature variation, and distortion occur. To elucidate the profile deteriorations induced by the lateral scaling, we analyzed the effect of the angular etching yield dependency of the incident ion fluxes into a given feature using the multiscale technology computer-aided design methodology. As one of the inherent features of the gas, incident angle θmax in which the sputtering yield achieves its maximum value is a crucial factor for analyzing and modeling etching profiles. Moreover, the impact of the heavy inert ion strikes on the unpreferred etching profiles was investigated. In this study, the synergy of lower energy ions, larger fluxes, and larger θmax of heavy inert ions decrease the feature-to-feature variation, reducing hard mask distortion without the etch rate reduction.</p

Asynchronous pulse-modulated plasma effect on the generation of abnormal high-energetic electrons for the suppression of charge-up induced tilting and cell density-dependent etching profile variation

The formation of high-energy electrons and ion fluxes induced by an abnormal electron heating mode in asynchronous pulse-modulated plasma was investigated using particle-in-cell simulation. We demonstrate that the abnormally high electron heating mode was induced only for a short time in the asynchronous pulsed plasmas. Furthermore, enhanced production of energetic electrons accompanies this electron heating. In particular, the higher energy electrons ( ε > 20 eV) are mainly produced by the abnormal electron heating during the first period of the abrupt sheath expansion phase in the asynchronous pulsed plasma with α1 =  α3 = 0.05. These high-energy electrons are crucial for tailoring the expansion of plasma density and neutralizing the surface charging for the HARC etching process. A synergy of higher energy electrons and higher density ion fluxes in asynchronous pulsed plasma can be a promising solution to reduce statistical variation and charging-induced profile deterioration without the etch rate reduction in 3D NAND fabrication.</p

TCAD augmented generative adversarial network for hot-spot detection and mask-layout optimization in a large area HARC etching process

Cost-effective vertical etching of plug holes and word lines is crucial in enhancing 3D NAND device manufacturability. Even though multiscale technology computer-aided design (TCAD) methodology is suitable for effectively predicting etching processes and optimizing recipes, it is highly time-consuming. This article demonstrates that our deep learning platform called TCAD-augmented Generative Adversarial Network can reduce the computational load by 2 600 000 times. In addition, because well-calibrated TCAD data based on physical and chemical mutual reactions are used to train the platform, the etching profile can be predicted with the same accuracy as TCAD-only even when the actual experimental data are scarce. This platform opens up new applications, such as hot spot detection and mask layout optimization, in a chip-level area of 3D NAND fabrication