Gold Gettering in Directly Bonded Silicon Wafers

Gold gettering in directly bonded silicon wafers was investigated. Wafers of (100) orientation were rotationally misoriented against each other by 1° or 25° and bonded by annealing at 1100°C for 2 hours in nitrogen. Transmission electron micrographs had shown two different bonding interface structures depending on the rotational angle. The bonded wafers were gold-deposited on one side and annealed for 3 hours at 950°C or 1000°C in vacuum. The spreading resistance was measured and the result showed a double-U profile in both 1°-misoriented and 25°-misoriented samples. Our results show for the first time that the bonding interface acts as a gettering site and that the bonding interface might be used to artificially introduce gettering sites close to the regions in which devices would be fabricated.