A Miniature Ionization Vacuum Sensor With a SiOₓ-Based Tunneling Electron Source

A miniature ionization vacuum sensor (IVS) based on an on-chip SiO
_x
-based tunneling electron source is reported. The vacuum sensor fabricated by microfabrication technologies exhibits a compact multilayered structure with overall dimensions of
$13\times 9\times2.7$
mm
³
, where the electron source chip, Si layer of the electron collector, Si layer of the ion collector, and glass spacers between them are stacked together by an anodic bonding method. Electron impact ionization occurs in a semiclosed cavity through the electron and ion collector layers and glass spacers. Because of the compact structure, low working voltage of SiO
_x
-based tunneling electron sources, and stable electron emission of the electron sources in a poor vacuum, a wide linear detection range from
$1.3\times 10^{-2}$
to 133 Pa and a sensitivity of
$8.3\times 10^{-4}$
Pa
⁻¹
have been demonstrated for the devices. These advantages, including miniature size, a detection range up to the rough vacuum regime, and the capability of batch fabrication with microfabrication technologies, make our IVSs promising in vacuum measurements.