Sputtered Copper Nitride-Copper Nitride Direct Bonding

A thin layer of copper nitride is sputtered onto silicon wafers by applying nitrogen plasma onto a copper target in a sputtering vacuum chamber. Some of the as-sputtered copper nitride is annealed at 300°C in a vacuum chamber for an hour, resulting in the reduction of the copper nitride into copper. To study its physical and chemical stability, the as-sputtered copper nitride is exposed to the cleanroom environment for varying duration. The exposed copper nitride is characterized for its sheet resistance and water contact angle. Simultaneously, the copper nitride-copper nitride direct bonding is performed at room temperature in cleanroom ambient. The pre-bonded samples are further annealed at 300°C for an hour. The bonded samples are examined for their shear strength to assess the bonding quality.