Plasma-induced growth mechanism of surface-state silver oxide in nanoscale for low-temperature bonding technology

For microelectronics packaging, we have previously invented a novel solid-state bonding technology by using in-situ self-reduction process of surface-state silver oxide. However, the underlying plasma-induced growth mechanism of surface-state silver oxide has still remained unclear in determining the optimal growth conditions for solid-state bonding. In the current study, the chemical state and crystallography of the plasma grown silver oxide nanocrystalline have been firstly confirmed by the X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) methods. Afterwards, the morphological transformation, surface roughness and size distribution of nanoparticles have been statistically studied with the scanning electron microscopy (SEM) and atomic force microscopy (AFM), demonstrating the impact of plasma discharge power and oxidation time on the silver oxide nanocrystalline. Moreover, the growth mechanism of surface-state silver oxide in nanoscale has been thoroughly elaborated and summarized into four distinctive stages, namely, (1) adsorption and nucleation, (2) particle accumulation, (3) hillocks formation, and (4) huge island formation. With its growth mechanism well-clarified, the surface-state silver oxide in nanoscale is expected to have a great potential as a temporary bonding medium in the development of low-temperature solid-state bonding technology for the advanced integrated circuits (IC) packaging with ultra-fine pitch.