Si-si Bonding Using Rf and Microwave Radiation

Electromagnetic radiation ranging in frequency from a few MHz to tens of GHz has been used to volumetrically heat silicon above 1000°C in only a few seconds. Typical power is <1.5 kW. This technique has successfully produced direct Si wafer-to-wafer bonds in only five minutes without the use of any intermediate glue layer. Infrared images indicate void free bonds, and knife-edge tests could not delaminate the wafers. In addition, four pairs of stacked wafers have been bonded simultaneously in 5 min., demonstrating the potential for multi-wafer bonds and high-throughput batch processing.