The University of Tokyo Department of Mechanical Engineering,Fracture Mechanics Laboratory.SAKAI & IZUMI group.

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Atomic-level stress analysis for semiconductor fabrication process

The intrinsic stress at hetero interface is one of key factors to cause the structural instability of micropatterning in semiconductor devices, and it is essential to quantitatively predict the intrinsic stress in terms of atomic structure. In this study, using a finite element method, we first cast the estimation problem that the lateral undulation buckling of micropatterning could be occurred when the intrinsic stress of the order of 1 GPa acts on the oxidized film capping a mask layer. Guided by the critical criterion, we construct the atomic model of dry etching, using a molecular dynamics method, and we simulate the oxidized film formation to irradiate oxygen atoms into an amorphous silicon (a-Si) surface. Our approach reveals that the film thickness depends on the incident energy and that the intrinsic stress exceeds 1 GPa for some conditions of the incident energy. Therefore, we conclude that it is possible for the oxidized a-Si layer formed by etching to trigger the buckling of micropatterning even if the unetched a-Si structure is under no stress.

 

・H.Tanaka, M. Inoue, et al., “Analysis of Oxidized Film Formation and Evaluation of Intrinsic Stress in the a-Si Layer of Semiconductor Microscopic Patterned Structures Using Molecular Dynamics Method”, Journal of Soc. of Mat. Sci. JAPAN, Vol. 65(2016) No. 2, pp.127-134 (In Japanese). (a)




semiconductor

(a)Schematic drawings of the simulation model of the oxide film formation for the a-Si surface structure.


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(b)Snapshots of the oxide film formation (The red spheres indicate oxygen atoms.)



 








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