A method includes bonding a first bond layer to a second bond layer through eutectic bonding. The step of bonding includes heating the first bond layer and the second bond layer to a temperature higher than a eutectic temperature of the first bond layer and the second bond layer, and performing a pumping cycle. The pumping cycle includes applying a first force to press the first bond layer and the second bond layer against each other. After the step of applying the first force, a second force lower than the first force is applied to press the first bond layer and the second bond layer against each other. After the step of applying the second force, a third force higher than the second force is applied to press the first bond layer and the second bond layer against each other.