Direct wafer bonding for photonic MEMS and packaging applications

A low temperature direct wafer bonding of semiconductor substrates has been envisaged. The method developed overcomes the previous techniques where high temperature is required for direct bonding. A combination of specific chemical cleaning and plasma treatment enables the wafers to be adhered together at room temperature. Heat treatment at around 220° C with pressure enables the wafers to be atomically bonded. TEM micrograph reveals that the bonded interface is uniform and smooth. In addition micro-Raman (MR) and SEM with EDAX were also used to investigate the bonded interface. Electrical measurements reveal that the interface does not obstruct the passage of current. This technique would be useful to fabricate photonic devices and also extended for packaging applications.