Patent ID: 7442570

Claim:
A method for bonding a CMOS wafer and a MEMS wafer, the CMOS wafer including an integrated circuit, the MEMS wafer including a MEMS device, the method comprising: depositing a germanium bonding layer on the MEMS wafer; forming a substantially aluminum bonding layer on the CMOS wafer, wherein the CMOS wafer is placed in a first chuck and the MEMs wafer is placed in a second chuck; aligning CMOS wafer and the MEMS wafer; and forming a eutectic bond between the germanium bonding layer on the MEMS wafer and the substantially aluminum metalization bonding layer on the CMOS wafer, wherein the eutectic bond is formed by keeping the CMOS wafer and the MEMS wafer apart until the temperature on each of the top and bottom chucks reaches a first predetermined temperature that is less than 450° C., inducing forming gas at an atmospheric pressure prior to bonding, providing a vacuum to remove the forming gas, applying a uniform force across the first chuck and the second chuck, and then ramping the temperature over the eutectic point of the aluminum/germanium bond to a second predetermined temperature that is less than 500° C. for a period not to exceed thirty minutes.