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In advanced packaging technology, the micro bump has become an important means of chip stacking and wafer interconnection. The reliability of micro bumps, which plays an important role in mechanical support, electrical connection, signal transmission and heat dissipation, determines the quality of chip packaging. Surface morphological defects are one of the main factors affecting the reliability of micro bumps, which are closely related to materials and bonding process parameters. In this paper, the electrodeposition process of preparing gold bumps is simulated at the atomic scale using the Kinetic Monte Carlo method. The differences in surface morphology and roughness of the plated layer are studied from a microscopic perspective under different deposition parameters. The results show that the gold micro bumps prepared by electrodeposition have better surface quality under conditions of lower deposition voltage, lower ion concentration and higher plating temperature, which can provide significant guidance for engineering applications. [ABSTRACT FROM AUTHOR]

A reciprocal electromagnetically induced transparency (EIT) effect is proposed in the complementary metasurface structure, which is composed of metal orthogonal strips beside a silicon substrate. The EIT effect of reciprocity is obtained whether the incident wave propagates from the positive (+z) or reverse (−z) direction. A multiband EIT window is also obtained in the structure of horizontal strip and substrate silicon as bright mode and vertical strip as dark mode by the finite difference time domain (FDTD) method. The transmission mechanism is interpreted by giving the current surface and electric field distributions at certain frequencies. A polarization insensitive EIT can be realized theoretically due to the structure is symmetrical in the x and y directions. The effective permittivity of the structure was calculated by the method of inversion to reveal the transmission spectra. These results can be applied in many areas, such as multiband slow-light devices, active sensing and bidirectional devices. [ABSTRACT FROM AUTHOR]