Characterization of parylene-assisted wafer bonding: long-term stability and influence of process chemicals

This paper presents wafer bonding using a thin parylene layer and reports detailed experimental data on: 1) bond strength and its dependence on bonding temperature, pressure, ambient, and time, 2) bond strength variation and stability up to two years post bond, and 3) bond strength variation after exposure to frequently used microfabrication process chemicals. The test results show that bond strength is mainly dependent on bonding temperature, does not vary more than 7% after two years under standard laboratory conditions when bonding is performed at or above 210°C, and remains within 89% of its original strength after one hour exposure to process chemicals such as AZ400K, BHF, MF319, Acetone, and IPA.