Abstract
SiC direct bonding using O2 plasma activation is investigated in this work. SiC substrate and n− SiC epitaxy growth layer are activated with an optimized duration of 60s and power of the oxygen ion beam source at 20 W. After O2 plasma activation, both the SiC substrate and n− SiC epitaxy growth layer present a sufficient hydrophilic surface for bonding. The two 4-inch wafers are prebonded at room temperature followed by an annealing process in an atmospheric N2 ambient for 3 h at 300 °C. The scanning results obtained by C-mode scanning acoustic microscopy (C-SAM) shows a high bonding uniformity. The bonding strength of 1473 mJ/m2 is achieved. The bonding mechanisms are investigated through interface analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Oxygen is found between the two interfaces, which indicates Si–O and C–O are formed at the bonding interface. However, a C-rich area is also detected at the bonding interface, which reveals the formation of C-C bonds in the activated SiC surface layer. These results show the potential of low cost and efficient surface activation method for SiC direct bonding for ultrahigh-voltage devices applications.
Highlights
Power electronic devices have been widely applied in consumer electronics, electric vehicles, grid control and industrial applications [1]
These results show the potential of low cost and efficient surface activation method for SiC direct bonding for ultrahigh-voltage devices applications
Transmission electron micrograph (TEM) and energy dispersive X-ray spectroscopy (EDX) are employed to analyze the bonding mechanism. These results suggest the potential of low cost and efficient surface activation method for SiC substrate bonding with the SiC epitaxy layer for ultrahigh-voltage devices applications
Summary
Power electronic devices have been widely applied in consumer electronics, electric vehicles, grid control and industrial applications [1]. Benefiting from the high breakdown electric field (Ebd ), which is approximately 10 times higher than that of Si-based devices, the SiCbased devices can operate in an ultrahigh-voltage region larger than 10 kV [9,10,11] It is very suitable for large electric power system applications for which a large current operation condition is normally required. Si-face of the epitaxy growth layer can be bonded with a SiC substrate before thinning and polishing, the problem of handling and processing caused by wafer bow can be effectively solved. Transmission electron micrograph (TEM) and energy dispersive X-ray spectroscopy (EDX) are employed to analyze the bonding mechanism These results suggest the potential of low cost and efficient surface activation method for SiC substrate bonding with the SiC epitaxy layer for ultrahigh-voltage devices applications
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