Hermetically sealed molecular spectroscopy cell
An illustrate method (and device) includes etching a cavity in a first substrate (e.g., a semiconductor wafer), forming a first metal layer on a first surface of the first substrate and in the cavity, and forming a second metal layer on a non-conductive structure (e.g., glass). The method also may include removing a portion of the second metal layer to form an iris to expose a portion of the non-conductive structure, forming a bond between the first metal layer and the second metal layer to thereby attach the non-conductive structure to the first substrate, sealing an interface between the non-conductive structure and the first substrate, and patterning an antenna on a surface of the non-conductive structure.
1. A device, comprising:
a non-conductive structure having opposite first and second surfaces;
a first metal layer on the second surface, the first metal layer having an opening that exposes a portion of the second surface;
a substrate having a third surface and a cavity that extends from the third surface into the substrate, the cavity having an internal pressure of less than 0.15 mbars;
a second metal layer on the third surface and on a surface of the cavity;
at least one bonding structure attaching a portion of the first metal layer to a portion of the second metal layer; and
an antenna on the first surface, so the opening is between the antenna and the cavity.
2. The device of claim 1 , wherein the cavity contains dipolar molecules.
3. The device of claim 2 , wherein the dipolar molecules are water molecules.
4. The device of claim 1 , wherein the non-conductive structure includes at least one of glass, ceramic, or silicon.
5. The device of claim 1 , wherein the substrate includes at least one of a semiconductor wafer or a ceramic.
6. The device of claim 1 , wherein the non-conductive structure includes glass, and the substrate includes a semiconductor substrate.
7. The device of claim 1 , wherein:
the antenna is a first antenna;
the device further comprises: an amplifier; a filter; a signal generator; and a second antenna on the first surface;
the signal generator has: a control input; and a signal generator output coupled to the first antenna;
the signal generator is configured to generate and adjust a frequency of a transmit signal at the signal generator output, based on a control signal at the control input;
the amplifier has: a first input coupled to the second antenna; a second input coupled to the signal generator output; and an amplifier output;
the amplifier is configured to generate an error signal at the amplifier output, based on: a receive signal from the second antenna; and the transmit signal from the signal generator; and
the filter has: a filter input coupled to the amplifier output; and a filter output coupled to the control input;
the filter is configured to generate the control signal, based on the error signal.
8. The device of claim 1 , wherein the at least one bonding structure hermetically seals the cavity.
9. A device, comprising:
a glass sheet having opposite first and second surfaces;
a first metal layer on the second surface, the first metal layer having an opening that exposes a portion of the second surface;
a semiconductor substrate having a third surface and a cavity that extends from the third surface into the semiconductor substrate;
a second metal layer on the third surface and on a surface of the cavity, a portion of the second metal layer attached to a portion of the first metal layer;
first and second antennas on the first surface; and
a transceiver electrically coupled to the first and second antennas, the transceiver configured to inject a transmit signal into the cavity through the first antenna, generate an error signal based on the transmit signal and a receive signal from the second antenna, and dynamically adjust a frequency of the transmit signal based on the error signal;
the cavity containing dipolar molecules and having an internal pressure of less than 0.15 mbars.
10. The device of claim 9 , wherein the transceiver includes:
a signal generator having: a control input; and a signal generator output coupled to the first antenna;
the signal generator configured to generate and adjust a frequency of the transmit signal at the signal generator output, based on a control signal at the control input;
an amplifier having: a first input coupled to the second antenna; a second input coupled to the signal generator output; and an amplifier output;
the amplifier configured to generate the error signal at the amplifier output; and
a loop filter having: a filter input coupled to the amplifier output; and a filter output coupled to the control input;
the loop filter configured to generate the control signal, based on the error signal.
11. The device of claim 9 , wherein the portion of the second metal layer is attached to the portion of the first metal layer by at least one bonding structure that hermetically seals the cavity.