Silicon-to-silicon wafer bonding with gold as intermediate layer

In this study, eutectic bonding process between two 4-inch, p-type silicon wafers has been successfully achieved. A gold pattern of varying height is firstly deposited on one silicon wafer prior to bonding. To further understand the eutectic bonding process, the effects of bonding temperature and gold height are investigated. When studying the effect of bonding temperature, the gold height is kept constant at 1.00 μm while the bonding temperature is varied from 375 to 475°C. It is found that bonding temperature of 400°C yielded the most satisfactory results, in terms of bonding efficiency, bond strength and interfacial integrity. Moreover, when studying the effect of gold height, the bonding temperature is kept at the optimized temperature of 400°C, with gold height varying from 0.20 to 1.40 μm. It is found that gold height of 1.00 μm yielded the best results.