Anodic nano-porous humidity sensing thin films for the commercial and industrial applications

Presented is a method to make anodic nano-porous humidity sensors using standard integrated circuit processes. These films are proposed as a replacement for polyamide based thin film humidity sensors. Standard titanium tungsten/aluminum multilayer films are deposited using commercial quality deposition equipment onto silicon (100) substrates. Films are anodized in 4% oxalic acid at 40 and 60 volts. Nano-porous humidity sensors are demonstrated that have a factor of 40 difference (dry to wet) in impedance at 20 Hz and a factor of 4 difference at 1 MHz. The complex impedance for saturated and dry films was presented.