Surface analysis of argon and oxygen plasma-treated gold for room temperature wafer scale gold-gold bonding

The effects of Ar and O
₂
plasma treatments on Au surface properties were investigated in terms of room temperature wafer-scale Au-Au bonding. X-ray photoelectron spectroscopy analysis indicated that O
₂
plasma treatment formed gold oxide (Au
₂
O
₃
) on Au surfaces, and bonded samples treated by O
₂
plasma showed weak bonding strength (0.14-0.16 J/m
₂
). It seems that Au
₂
O
₃
impeded Au-Au bonding. On the other hand, strong Au-Au bonding was obtained by using Ar plasma treatment, and bonded samples were fractured at the bulk wafers during the blade test.