Abstract
Abstract The simple Au Si eutectic, which melts at 363 °C, can be used to bond Si wafers. However, faceted craters can form at the Au/Si interface as a result of anisotropic and non-uniform reaction between Au and crystalline silicon (c-Si). These craters may adversely affect active devices on the wafers. Two possible solutions to this problem were investigated in this study. One solution was to use an amorphous silicon layer (a-Si) that was deposited on the c-Si substrate to bond with the Au. The other solution was to use solid-state bonding instead of eutectic bonding, and the wafers were bonded at a temperature (350 °C) below the Au Si eutectic temperature. The results showed that the a-Si layer prevented the formation of craters and solid-state bonding not only required a lower bonding temperature than eutectic bonding, but also prevented spill out of the solder resulting in strong bonds with high shear strength in comparison with eutectic bonding. Using amorphous silicon, the maximum shear strength for the solid-state Au Si bond reached 15.2 MPa, whereas for the eutectic Au Si bond it was 13.2 MPa.
Published Version
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