Bulletin of the American Physical Society
73rd Annual Gaseous Electronics Virtual Conference
Volume 65, Number 10
Monday–Friday, October 5–9, 2020; Time Zone: Central Daylight Time, USA.
Session XF3: Plasma EtchingLive
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Chair: Wei Tian, Taiwan Semiconductor Manufacturing Corporation |
Friday, October 9, 2020 9:45AM - 10:15AM Live |
XF3.00001: Advancements in Feature Scale Simulations Invited Speaker: Paul Moroz Main industrial applications of plasmas are for the materials processing, in particular, for the semiconductor industry. Complexities of modern multi-step processes and used chemistries, as well as requirements on accuracy of processing constantly increase, while features become smaller and of higher aspect ratio. As result, searching for optimal experimental parameters becomes more difficult and could benefit significantly from numerical simulations. The corresponding feature-scale (FS) simulation codes are thus become of great importance as no other numerical approach (at least, at present time) is capable of simulating feature profiles resulted from materials processing, be that due to etching, deposition, or both those processes going on at the same time or one after another in cycles. Plasma ion implantation is also often happens during etching processes and it affects the results of etching. Simulation includes a few steps: (1) compute the species coming to the surface from the plasma and their energy and angle distributions, (2) estimate all surface reactions due to incidence of incoming species as well as by-products of surface reactions, and (3) use a FS simulation, such as FPS3D [1-4], to simulate the results of etching or deposition. If simulation does not correspond to experimental results, we have to adjust the parameters, modify a set of incoming species, or their energy and angular distributions, or the surface reactions. If we are sure that the plasma simulations are correct then the surface reactions would be the main culprit. The surface reactions are typically poorly known. Because there is a large set of surface reactions, and each reaction might depend on a few parameters, we typically come to a problem of multi-parameter optimization. In this presentation, we discuss the design of FPS3D as a general FS code applicable to most situations arising in materials processing. Examples of simulations are provided for very different chemistries and scales, including ALE and ALD, as well as the HAR etching. [1] P. Moroz, IEEE Trans. on Plasma Science, 39, 2804 (2011). [2] P. Moroz, D. J. Moroz, ECS Transactions, 50, 61 (2013). [3] P. Moroz, D. J. Moroz, J. Physics: CS 550, 012030 (2014). [4] P. Moroz, D. J. Moroz, Japan. J. Appl. Phys. 56, 06HE07 (2017). [Preview Abstract] |
Friday, October 9, 2020 10:15AM - 10:30AM Live |
XF3.00002: Optimization of Etching Recipes for Si Trenches with Self-Aligned Quadruple Patterning Mask by Transfer Learning Naoto Takano, Hyakka Nakada, Takeshi Omori As technologies for semiconductor processing advance, the critical dimensions of devices have shrunk. Proficient engineers have optimized etching recipes (control parameters in etchers) to obtain target etching profiles required for state-of-the-art devices by using knowledge gained from etching results in the process development for previous generation devices. However, as the target profiles have become complicated, the number of etching processes to fabricate state-of-the-art devices has increased. Therefore, the shortage of proficient engineers to optimize recipes for such devices is becoming severe. To solve this problem, we utilize transfer learning to automatically predict the optimal recipes for state-of-the-art devices by learning etching data obtained in the process development for previous generation devices. Our transfer learning model was trained on etching data of Si trenches with a width of 750 nm. The model predicted the optimal recipes for etching Si trenches with a width of 12.5 nm with a self-aligned quadruple patterning mask. We found a vertical trench with an aspect ratio of 8 was etched with one-third of the training data in the conventional machine learning-based methods [1,2]. [1] H. Nakada et al., GEC 2017, [2] H. Nakada et al., GEC 2018 [Preview Abstract] |
Friday, October 9, 2020 10:30AM - 10:45AM Live |
XF3.00003: Quantum Tunneling with Space Charge Effects in Thin Insulating Gaps. Sneha Banerjee, Peng Zhang When two conductors are separated by sufficiently thin insulating layer, electrical current can flow between them by quantum tunneling. Space charge and electron exchange correlation potential in the insulating gap influence this current transport significantly. These effects are important to high current diodes, electrical contacts, and electron emitters. Here we present a self-consistent model (SCM) to calculate the tunneling current density in nano- and subnano-meter dissimilar metal-insulator-metal (MIM) junctions including these effects. In dissimilar MIM junctions, the current is polarity dependent. The forward and reverse current-voltage curves and their crossover behaviors are examined in detail in various regimes for a wide range of material properties [1]. We apply this SCM to characterize the current flow in a two-dimensional (2D) tunneling type electrical contacts [2]. We found that current crowding near the edges can be reduced significantly by spatially engineering the interfacial layer. [1] S. Banerjee and P. Zhang, AIP Adv., 9, 085302 (2019), [2] S. Banerjee, J. Luginsland, and P. Zhang, Sci. Rep., 9, 14484 (2019). [Preview Abstract] |
Friday, October 9, 2020 10:45AM - 11:15AM Live |
XF3.00004: Dynamics of physicochemical reactions in time-modulation of plasmas for advanced semiconductor processes Invited Speaker: Masaru Hori Plasma etching processes of high-aspect-ratio contact holes (HARC) and fine pattern fabrication with an atomic layer (ALE) are key technologies of semiconductor manufacturing. High-aspect-ratio contact hole (HARC) fabrications need to satisfy less damage and highly selective removal of materials, and less distortions in etched profiles, causing by the distortions of ion trajectories inside the deep contact holes due to charge build-up positively. Recently, the negative DC-bias imposition to the top electrode in the short-pulsing capacitively coupled plasma (CCP) etcher solves this issue. In atomic layer etching of silicon oxides and nitrides, fluorocarbon, hydrogen, oxygen and/or fluorine gas plasmas were alternatively performed. For such time-modulation plasmas, a rapid electron density decay was observed in the afterglow of the pulsed plasma, due to the attachment of electrons to large fluorocarbon radicals and/or parent molecules in the afterglow, which suggests the existence of an ion--ion plasma composed of negative and positive ions with negligible electrons. These dynamics of ions together with radicals in time-modulation plasma processes enables to control the physicochemical reactions on the materials towards the high performances of HARC and ALE. [Preview Abstract] |
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