Atomic-scale cellular model and profile simulation of poly-Si gate etching in high-density chlorine-based plasmas: Effects of passivation layer formation on evolution of feature profiles

Atomic-scale cellular model has been developed to simulate the feature profile evolution during poly-Si gate etching in high-density Cl2 and Cl2∕O2 plasmas, with emphasis being placed on the formation of passivation layers on feature surfaces. The model took into account the behavior of Cl+ ions, Cl and O neutrals, and etch products and byproducts of SiClx and SiClxOy in microstructural features. The transport of ions and neutrals in microstructures and in substrates was analyzed by the two-dimensional Monte Carlo calculation with three velocity components. The surface chemistry included ion-enhanced etching, chemical etching, and passivation layer formation through surface oxidation and deposition of etch products and byproducts. The computational domain was taken to consist of two-dimensional square cells or lattices of atomic size, and the evolving interfaces were represented by removing Si atoms from and/or allocating them at the cells concerned. Calculations were performed for different line-and-spac...

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