Thin-film vacuum packaging based on porous anodic alumina (PAA) for infrared (IR) detection

In this paper, we present a thin-film vacuum packaging method for infrared (IR) detection. It is based on the formation of porous anodic alumina (PAA) with vertical nanopores as a supporting layer and an etch hole for the removal of the sacrificial layer. To etch away the sacrificial material, the etchant penetrates into the cavity underneath the PAA film through the nanopores in the PAA. In addition, the PAA is capable of high transmittance in the IR wavelength range. To seal the packaging, an IR-transparent material is post-deposited over the PAA film in a vacuum ambient environment. The vacuum level of the packaging is verified by measuring the center deflection of the sealing layer and the long-term hermeticity is monitored for 60 days. The IR transmittance of the PAA membrane and a sealing layer on the PAA was also measured for IR applications.