A new low temperature silicon wafter-to-wafer bonding with nickel silicide at an annealing temperature of 440 degrees C is presented. Good adhesion between the wafers has been achieved as measured by tensile strength testing, and observed by scanning electron microscopy. The bonding area percentage, measured by ultrasonic testing, is larger than 90%. The nickel silicide formed at the interface is NiSi, as observed by X-ray diffraction and Auger electron spectroscopy. The bonded pairs show good contact characteristics.