Suppression of H2O absorption by hydrophobic-like surface of SiOx without Si-OH group

A mechanism of H
2
O absorption into SiO
x
films for forming hydrophobic surfaces is experimentally studied with annealing at several temperatures followed by exposure to several environment conditions. A key requisite to suppress H
2
O absorption was found to be a hydrophobic-like surface of SiO
x
, which was formed by annealing above 700°C, which completely removes the Si-OH group. This result indicates the possibility to fabricate the completed SiO
x
films that almost prevent H
2
O absorption regardless of the air exposure time periods.