Silicon wafer bonding with an insulator interlayer using RF dielectric heating

Abstract

A new silicon wafer bonding process based on dielectric heating of an intermediate layer has been developed and characterized. This method uses a capacitive RF field to heat a dielectric interlayer up to its glass transition temperature and permanently join two wafers. A 500 W 14 MHz source was used to deliver RF power to the substrates. Two inches diameter silicon wafers with 2-20 /spl mu/m thick polyimide intermediate layers were successfully bonded (> 95% bond area) in less than 7 minutes. The silicon substrate temperature remained below 280/spl deg/C throughout the bonding process. The results of the pull tests indicate a bond strength of >1.5 MPa for fully cured substrates, which is greater than the strength of other low-temperature adhesive bonds.