A thermal type vacuum gauge is disclosed herein and includes a first floating structure, a second floating structure, a first cavity and a second cavity. The first floating structure is formed by the first insulating layer, the second insulating layer, and the first sensing resistor. The second floating structure is formed by the second insulating layer, and the second sensing resistor. The first cavity and the second cavity are respectively formed below the first floating structure and the second floating structure. The thermal type vacuum gauge is implemented in a measurement circuit having a first resistor, a second resistor, a third resistor and a fourth resistor. The first sensing resistor and the second sensing resistor are respectively implemented to be as at least two of the first resistor, the second resistor, the third resistor and the fourth resistor of the measurement circuit.

A load lock pressure gauge comprises a housing configured to be coupled to a load lock vacuum chamber. The housing supports an absolute vacuum pressure sensor that provides instantaneous high vacuum pressure signal over a range of high vacuum pressures and a differential diaphragm pressure sensor that provides an instantaneous differential pressure signal between load lock pressure and ambient pressure. The housing further supports an absolute ambient pressure sensor. A low vacuum absolute pressure is computed from the instantaneous differential pressure signal and the instantaneous ambient pressure signal. A controller in the housing is able to recalibrate the differential diaphragm pressure sensor based on measured voltages of the sensor and a measured ambient pressure during normal operation of the pressure gauge with routine cycling of pressure in the load lock.

A load lock pressure gauge comprises a housing configured to be coupled to a load lock vacuum chamber. The housing supports an absolute vacuum pressure sensor that provides instantaneous high vacuum pressure signal over a range of high vacuum pressures and a differential diaphragm pressure sensor that provides an instantaneous differential pressure signal between load lock pressure and ambient pressure. The housing further supports an absolute ambient pressure sensor. A low vacuum absolute pressure is computed from the instantaneous differential pressure signal and the instantaneous ambient pressure signal. A controller in the housing is able to recalibrate the differential diaphragm pressure sensor based on measured voltages of the sensor and a measured ambient pressure during normal operation of the pressure gauge with routine cycling of pressure in the load lock.

The disclosed invention provides a bridge voltage inversion circuit for vacuum gauge and a pressure gauge sensor that includes the bridge voltage inversion circuit. The bridge voltage inversion circuit for a pressure gauge includes a reference capacitance, a sensor capacitance, and a transformer including a primary winding and a secondary winding that outputs a bridge voltage. The reference capacitor is connected to a first side of the secondary winding of the transformer, and the sensor capacitor is connected to a second side of the secondary winding of the transformer. The sensor capacitor senses and responds to a pressure, and a capacitance of the sensor capacitor is at a minimum when the pressure is at vacuum. The capacitance of the sensor capacitor at vacuum is less than a capacitance of the reference capacitor.

The disclosed invention provides a bridge voltage inversion circuit for vacuum gauge and a pressure gauge sensor that includes the bridge voltage inversion circuit. The bridge voltage inversion circuit for a pressure gauge includes a reference capacitance, a sensor capacitance, and a transformer including a primary winding and a secondary winding that outputs a bridge voltage. The reference capacitor is connected to a first side of the secondary winding of the transformer, and the sensor capacitor is connected to a second side of the secondary winding of the transformer. The sensor capacitor senses and responds to a pressure, and a capacitance of the sensor capacitor is at a minimum when the pressure is at vacuum. The capacitance of the sensor capacitor at vacuum is less than a capacitance of the reference capacitor.

A Process Critical Thermal Conductivity Gauge (PCTCG) instrument relies on gauge chamber wall above-ambient-temperature-control (AATC) to provide improved accuracy and thermal stability with reduced and linearized temperature coefficients. A sensor resistor is exposed to gas pressure in a gauge chamber. AATC is provided by control of a heater that heats a chamber wall to control temperature difference between the sensor resistor and chamber wall. An example application of this technology is to end-point detection in lyophilization where the TCG is used to track partial pressures of water in binary gas mixtures.

A Process Critical Thermal Conductivity Gauge (PCTCG) instrument relies on gauge chamber wall above-ambient-temperature-control (AATC) to provide improved accuracy and thermal stability with reduced and linearized temperature coefficients. A sensor resistor is exposed to gas pressure in a gauge chamber. AATC is provided by control of a heater that heats a chamber wall to control temperature difference between the sensor resistor and chamber wall. An example application of this technology is to end-point detection in lyophilization where the TCG is used to track partial pressures of water in binary gas mixtures.

A heat-loss pressure microsensor for measuring a gas pressure is disclosed that includes a plurality of pressure gauges arranged proximate to one another on a substrate. The gauges may include a pair of gauges, each gauge including a thermistor having an electrical resistance that varies with its temperature, the thermistor's temperature being responsive to the gas pressure, a platform to receive the thermistor, and a support structure to hold the platform above the substrate. Each gauge may be configured to produce a gauge output signal related to the electrical resistance of its thermistor. The two gauges are configured with their platforms having equal nominal perimeters and different nominal surface areas, and their support structures having the same nominal geometry. A differential signal may be obtained from the two gauge output signals. The differential signal conveys information about the gas pressure and exhibits reduced sensitivity to fabrication-related dimensional variations.

A thermal conductivity gauge measures gas pressure within a chamber. A sensor wire and a resistor form a circuit coupled between a power input and ground, where the sensor wire extends into the chamber and connects to the resistor via a terminal. A controller adjusts the power input, as a function of a voltage at the terminal and a voltage at the power input, to bring the sensor wire to a target temperature. Based on the adjusted power input, the controller can determine a measure of the gas pressure within the chamber.

A thermal conductivity gauge measures gas pressure within a chamber. A sensor wire and a resistor form a circuit coupled between a power input and ground, where the sensor wire extends into the chamber and connects to the resistor via a terminal. A controller adjusts the power input, as a function of a voltage at the terminal and a voltage at the power input, to bring the sensor wire to a target temperature. Based on the adjusted power input, the controller can determine a measure of the gas pressure within the chamber.