A Thin Film Porous Alumina Vacuum Package Utilizing a Pore Sealing Getter

This work reports a thin-film encapsulated package with porous alumina as the capping layer and titanium as a pore-sealing getter. The titanium-gold film seals the thin film package and acts as the getter. Since the getter is not exposed to the elements, fouling of the getter is prevented. EDX measurements confirm that the getter material did not penetrate the package through the nanopores. The process is a low thermal budget process, with the getter activation (300 °C for 1 hour) being the only step where the temperature is raised. A Silicon Pirani gauge was used to monitor the pressure changes inside the sealed cavity. After the getter activation, a decrease in the pressure from
$50 \mu $
Torr to
$3.9 \mu $
Torr was seen for the first few days, and no noticeable change afterward. The hermeticity of the thin-film encapsulated package was examined, and the vacuum level inside the package remained the same for the last 510 days. In addition to providing a stable hermetic package, the getter may be activated in-circuit by resistive heating in case of pressure increases after many years of operation. [2023]–[0034]