A study of Si wafer bonding via methanol capillarity

The effects of capillary bonding of Si wafers in methanol have been investigated. Wafers brought into contact in alcohol generally leads to less particle trapping at the interface, and that liquid surface tension is useful in pulling bonding wafer together. The intrusion of methanol at the interface appears to affect the bond strength of hydrophilic bonding Si wafers where the strengthening mechanism is primarily due to the escaping of H₂O molecules from the interface. For hydrophobic wafers the use of methanol capillarity and dried in an inert ambient appears to prevent or minimize oxidation of the contacting surfaces. The experimental result supports the notion that such wafer pairs can indeed be heat-treated to form covalent bonds in between without resorting to high vacuum processing.