Method and apparatus to reduce the leakage rate of a hermetic cavity

A chip scale vapor cell comprising:

• a first substrate;
• a second substrate bonded to the first substrate with a bonding material, the second substrate comprising an upper surface and a lower surface;
• a primary hermetic cavity comprising a first bottom wall and first sidewalls formed in the first substrate and a first top wall formed by the lower surface of the second substrate;
• a secondary hermetic cavity comprising a second bottom wall and second sidewalls formed in the first substrate, a second top wall formed by the lower surface of the second substrate, the secondary hermetic cavity being separate from the primary hermetic cavity and surrounding a perimeter of the primary hermetic cavity;
• and
• a gas sealed in the primary hermetic cavity and the secondary hermetic cavity at an initial pressure, the gas comprising a dipolar molecule;
• the first bottom wall, first sidewalls and first top wall comprising a conductive surface, and the first top wall comprising:
• a first non-conductive aperture on the lower surface of the second substrate that provides an electromagnetic field entrance to the primary hermetic cavity;
• and a second non-conductive aperture on the lower surface of the second substrate;
• and spaced from the first non-conductive aperture, that provides an electromagnetic field exit from the primary hermetic cavity.

A millimeter wave atomic clock apparatus comprising:

• a vapor cell, comprising:
• a first substrate,
• a second substrate bonded to the first substrate with a bonding material, the second substrate comprising an upper surface and a lower surface,
• a primary hermetic cavity comprising a first bottom wall and first sidewalls formed in the first substrate and a first top wall formed by the lower surface of the second substrate,
• a secondary hermetic cavity comprising a second bottom wall and second sidewalls formed in the first substrate, a second top wall formed by the lower surface of the second substrate, the secondary hermetic cavity being separate from the primary hermetic cavity, the secondary hermetic cavity surrounding a perimeter of the primary hermetic cavity and
• a dipolar molecular gas sealed in the primary hermetic cavity and the secondary hermetic cavity at a given initial pressure;
• and
• a transceiver circuit mounted to the second substrate and electrically coupled to provide an alternating electrical output signal at a first end of the primary hermetic cavity and to receive an alternating electrical input signal at a second end of the primary hermetic cavity, the transceiver circuit coupled to selectively adjust a frequency of the alternating electrical output signal and to provide a reference clock signal.