JP2012198187A - Micro pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure a pressure value in a vacuum environment without disturbing the environment.SOLUTION: A micro pressure sensor is composed of a heat conduction type pressure sensor part 2 arranged on a necessary position in a vacuum device and a control part 3 arranged on an outer wall of the vacuum device. The pressure sensor part 2 includes: a polymeric film support having a cavity part formed by a bottom and a cylindrical or square frame; a polymeric film 21 stuck to the upper surface of the frame of the polymeric film support by adhesive; one pressure sensor 22 arranged on a center part of the polymeric film 21; and one or more temperature sensors 23 arranged on the periphery of the pressure sensor 22. The pressure sensor 22 and the temperature sensors 23 are connected to a control part 3 respectively through electrodes. The control part 3 applies heating power to the pressure sensor 22 to control heating to a fixed temperature, the temperature sensors 23 measure the peripheral temperatures of the pressure sensor 22 by resistance changes, and a pressure value corresponding to the heating power in the vacuum device is corrected by the resistance changes to measure an accurate pressure value in the vacuum device.

Description

  The present invention relates to a micro pressure sensor that can be used in a heat conduction vacuum gauge that measures the amount of heat taken away by a gas as a temperature change of a sensor material.

  In various thin film forming processes using a vacuum applied processing apparatus, the proper vacuum quality and quantity in the apparatus greatly affects the characteristics of the thin film to be formed.

In forming a thin film using a conventional vacuum processing apparatus, it can be attached only outside the apparatus because of the size of a vacuum gauge for measuring the pressure in the apparatus, so that only a temporal / location average value can be known. Even if there is some difference in the proper vacuum quality and quantity set in advance before or during thin film formation, there is often no clear difference from the pressure value of the measuring instrument, etc. It is often the case that the defect is known only after the evaluation. When forming a thin film in a vacuum applied processing apparatus, it is necessary to measure pressure over a wide range from atmospheric pressure (10 ⁵ Pa) to 10 ⁻⁵ Pa, and in the current measuring equipment, the pressure that can be measured by each measuring instrument. Since the range is narrow, it is necessary to use a measuring device for measuring pressure by a plurality of different methods.
In addition, as described above, since the size of the existing vacuum gauge for measuring the pressure is large, it is impossible to measure the pressure in a narrow space such as in the pipe or before and after the exhaust port in real time. In addition, as described in Patent Document 1, a microfabrication technique using silicon as a substrate material is generally used for micronization of a sensor that detects a change in heat conduction of a gas. However, a complicated production process is required. In addition, the cross-linked structure is fragile and the usable temperature range is limited.

The gas molecules follow the Maxwell distribution, and pressure measurement was performed based on the premise that the pressure is uniform at all points in the vacuum apparatus. However, in actuality, various gases are introduced into the vacuum apparatus for forming the electronic component device, so that the pressure value is measured with a vacuum gauge attached to the outer wall of the vacuum apparatus. In addition, since the sensor size is large, the sensor cannot be installed inside the vacuum apparatus, and it is only possible to perform a simulation.
Although the pressure state when actually forming a thin film is thought to greatly affect the properties of the thin film, there has been no means to measure so far. If the pressure distribution in the vacuum environment can be measured by the micro pressure sensor, it can greatly contribute to the development of the electronic component device forming field.

  JP 2005-308676 A

In a thin film formation process using a vacuum applied processing apparatus, there is no measuring instrument that can measure a wide range of pressures from atmospheric pressure (10 ⁵ Pa) to 10 ⁻⁵ Pa with a single sensor. At present, due to the problem of sensor size, it must be installed at a specific location on the outer wall of the vacuum device, and the pressure value in the narrow space such as the inside of the device where the thin film is actually formed or the piping part cannot be known. Microfabrication technology that uses silicon as a substrate material is generally used to make sensors that detect changes in the heat conduction of gas, but it requires a complicated fabrication process and the bridging structure is fragile. There are restrictions on the usable temperature range.
In addition, a method for measuring a pressure value in a special space called a vacuum environment without disturbing the environment has not been established.

A micro pressure sensor comprising a heat conduction type pressure sensor unit 2 disposed at a required location in a vacuum device and a control unit 3 disposed on an outer wall of the vacuum device,
The pressure sensor unit 2 includes a polymer film support 24 formed of a bottom surface and a cylindrical or square frame and having a cavity 25, and the polymer film 21 is bonded to the upper surface of the frame of the polymer film support 24. The pressure sensor 22 is attached to the central portion of the polymer film 21, and one or a plurality of temperature sensors 23 are provided around the pressure sensor 22. Are respectively connected to the control unit 3 via electrodes,
The control unit 3 applies heating power to the pressure sensor 22 to control heating to a constant temperature, measures the temperature around the pressure sensor 22 with the temperature sensor 23 by a resistance change, and vacuum corresponding to the heating power by the measured resistance change. A micro pressure sensor characterized in that an accurate pressure value in a vacuum apparatus is measured by correcting a pressure value in the apparatus.

  The micro pressure sensor, wherein the pressure sensor 22 is a tantalum-aluminum composite nitride.

  The lower portion of the polymer film 21 on which the pressure sensor 22 is mounted is a hollow portion 25 of the polymer film support 24, thereby reducing the heat capacity and improving the pressure sensor 22 sensitivity and responsiveness. A micro pressure sensor.

  A micro pressure sensor characterized in that the material of the polymer film 21 is polyimide.

1) Miniaturization is possible while ensuring an effective heat exchange area, and the response speed is fast due to the reduction of sensor heat capacity by using thin film and polymer film.・ Control can be realized.
2) The pressure over a wide range from atmospheric pressure (10 ⁵ Pa) to 10 ⁻⁵ Pa can be measured.
3) Since a thin film is used, it is possible to reduce the size while maintaining an effective heat exchange area.
4) It is possible to measure in real time the positional and temporal changes in the pressure value in the chamber of the vacuum apparatus in which the thin film is actually formed, and the pressure value in a narrow space such as a pipe section. 5) Pressure sensor Because of the characteristics of the tantalum-aluminum composite nitride material, a simple sensor pattern can be used, and in the sensor formation process using an ultra-thin heat-resistant polymer film on the substrate, effective heat exchange is performed as necessary. It is possible to easily change the area and the sensor pattern.

Configuration of the micro pressure sensor of the present invention 1 is a cross-sectional view of the micro pressure sensor of the present invention taken along line AA in FIG. Principle of the micro pressure sensor of the present invention Principle of temperature correction of the micro pressure sensor of the present invention Control circuit for micro pressure sensor of the present invention

The micro pressure sensor of the present invention has a structure in which a thin film material having a high temperature coefficient of resistance is formed on a polymer film and has a structure capable of accurately measuring the difference between the sensor temperature and the ambient temperature (temperature fixed point). Thus, it is possible to measure a wide pressure range from atmospheric pressure to 10 ⁻⁵ Pa using a single heat conduction sensor.

  By using a thin sensor material with a high temperature coefficient of resistance and using a very thin polyimide substrate as a polymer film, the heat capacity can be reduced and the difference between the sensor temperature and the ambient temperature (temperature fixed point) can be accurately measured. The structure is small, wide range, and high speed response. By using a metal mask for film formation, since it is a simple manufacturing process that does not require a complicated fine processing technique, it is possible to easily change the effective heat exchange area and the sensor pattern as necessary.

1 and 2 show the configuration of the micro pressure sensor of the present invention.
The micro pressure sensor 1 according to the present invention includes a heat conduction type pressure sensor unit 2 disposed at a necessary position in a vacuum apparatus and a control unit 3 disposed on an outer wall of the vacuum apparatus.
The pressure sensor unit 2 includes a polymer film 21, a pressure sensor 22, a temperature sensor 23, a polymer film support 24, a cavity 25, and an adhesive 26.
The polymer film support 24 is formed of a bottom surface and a cylindrical or square frame, and has a container shape in which a hollow portion 25 is formed. The polymer film 21 is attached to the upper surface of the frame of the polymer film support 24 with an adhesive 26 so as to cover the entire upper surface of the polymer film support 24, and one pressure sensor is provided at the center of the polymer film 21. 22 and its periphery, for example, one or more temperature sensors 23 are provided on the upper surface of the frame of the polymer film support 24. Each pressure sensor 22 and the temperature sensor 23 are connected to the control unit 3 by a lead wire 4 via electrodes 221, 222 and electrodes 231, 232, respectively.
The pressure sensor 22 having a high temperature coefficient of resistance is mounted at the center of the polymer film 21, and the heat capacity is reduced by forming a cavity 25 of the polymer film support 24 under the polymer film 21 to be placed. The sensitivity is improved by reducing the sensitivity.

Since the temperature sensor 23 having a high resistance temperature coefficient is arranged at a distance from the pressure sensor 22 provided in the central portion of the polymer film 21 and arranged on the upper part of the cylindrical frame of the polymer film support 24, The accuracy of measuring the internal temperature of the vacuum apparatus can be obtained, and the temperature correction of the pressure sensor as described later can be performed accurately.
In this way, the pressure sensor 22 and the temperature sensor 23 are arranged on the same polymer film 21 and have a structure that can accurately measure the difference between the sensor temperature and the ambient temperature (temperature fixed point). A wide pressure range from atmospheric pressure to 10 ⁻⁵ Pa, which was possible, can be measured by a single heat conduction sensor.

The material of the pressure sensor 22 is a composite nitride made of tantalum and aluminum, and has a high resistance temperature coefficient. The pressure sensor 22 is voltage-driven by the control unit 3 and controlled to be heated to a constant temperature via the electrodes 21 and 22. The heated pressure sensor 22 is deprived of heat by the gas, but is heated and controlled at a constant temperature by the pressure sensor driving unit 31 of the control unit 3.
The composite nitride made of tantalum and aluminum, which is the material of the pressure sensor 22, has a high resistance temperature coefficient. The temperature coefficient of resistance of the composite nitride material as the sensor material is −7000 to −14000 ppm / ° C., and particularly preferably −12000 to −14000 ppm / ° C. The specific resistance is 1.0 × 10 ^{−1 to} 2.0 Ω · cm, and particularly preferably 1.0 × 10 ^{−1 to} 1.0 Ω · cm. The thickness of the thin film of the pressure sensor 22 is preferably about 200 to 500 nm.

  The material of the temperature sensor 23 is the same composite nitride made of tantalum and aluminum as the pressure sensor 22 and has a high resistance temperature coefficient. A minute current is applied, the ambient temperature is calculated from the obtained resistance value, and used for correction.

  The material of the polymer film 21 is polyimide, and the thickness is about 1 to 50 μm.

  As a material of the electrodes 221, 222, 231, 232, a metal thin film such as Pt, Ni, Cu, Ag, Au, Al is used. Select one or more according to the sensor environment (atmosphere, temperature, presence of corrosive gas, etc.). The thin film of these electrodes is formed by a vapor phase method such as sputtering, ion plating, or CVD. Among these, sputtering is preferable. After the sputtering is completed, the obtained thin film is heat-treated at 150 to 500 ° C. as necessary, and is appropriately selected according to the substrate material to be used. For example, when the polymer film 21 is used as a substrate, it is preferably about 150 to 300 ° C. in consideration of the heat resistant temperature of the film.

  The polymer film support 24 is formed of a bottom surface and a cylindrical or square frame, and has a container shape in which a hollow portion 25 is formed. The material is stainless steel.

  The adhesive 26 is used to attach the polymer film 21 to the polymer film support 24. The adhesive 26 is a thermoplastic heat conductive adhesive.

  Lead wires are nickel, Ag wires, Au wires, Al wires, Cu wires, or metal foils made of these as raw materials, connected to hermetic elements using In, solder, Ag paste, etc. Take out. It is preferable to use a nickel wire with a wire diameter of 100 μm or a nickel foil with a thickness of 5 μm or less and connect with In or solder.

  FIG. 3 is a principle diagram of the micro pressure sensor of the present invention. When the gas molecules P of the vacuum device take away the amount of heat from the pressure sensor 22, the temperature changes and the resistance value changes. The change in resistance value is detected as a pressure value.

FIG. 4 shows the temperature correction principle of the micro pressure sensor of the present invention.
The horizontal axis represents the reference pressure, and the vertical axis represents the pressure value obtained from the heating power of the pressure sensor. Heating control is performed to keep the pressure sensor 22 at a constant temperature, and the heating power is associated with the pressure value. The heating power of the pressure sensor 22 depends on the temperature of the gas molecule P. If the temperature is low, the amount of heat taken away from the pressure sensor 22 is large, so that the heating power is large. If the temperature is high, the amount of heat taken away from the pressure sensor 22 is small. Becomes smaller. Therefore, the pressure sensor temperature and the temperature of the gas molecule P are precisely measured and corrected to a normalized temperature.

FIG. 5 shows the configuration of the control unit of the micro pressure sensor of the present invention. The control unit 3 includes a pressure sensor drive unit 31, a temperature measurement unit 32, a temperature correction unit 33, and a display unit 34.
The pressure sensor 22 arranged at the center of the polymer film 21 is controlled to be heated to a constant temperature via the electrodes 221 and 222. The heated pressure sensor is deprived of heat by 22 gases, but is heated to a constant temperature by the pressure sensor driving unit 31.

The temperature sensor measurement unit 32 measures the resistance change of the temperature sensor 23 via the electrodes 231 and 232. Since the temperature sensor 23 is disposed on the polymer film 21 of the frame of the polymer film support 24, even if the pressure sensor 22 disposed in the center of the polymer film 21 is heated, it is not affected by the temperature. . With this structure, the temperature of the gas can be accurately measured.
The temperature correction unit 33 is controlled by the pressure sensor driving unit 31 and the pressure sensor 22 is deprived of heat by the gas, but the amount of heat deprived by the temperature of the gas is different. A change in the temperature of the gas is measured by the temperature measurement unit 32 as a resistance change of the temperature sensor 23, and the temperature correction unit 33 performs a temperature correction calculation. Displayed on the display unit 34 as the pressure value of the vacuum device associated with the heating power of the pressure sensor driving unit 31 performed by the temperature correction unit 33 (based on the correspondence table of the heating power and the pressure value of the vacuum device obtained in advance) To do.
In this way, the control unit 3 controls the pressure sensor 22 to be heated to a constant temperature with the heating power associated with the pressure value in the vacuum apparatus, and the temperature sensor 23 measures the temperature around the pressure sensor 22 by resistance change. The pressure in the vacuum apparatus can be accurately measured by correcting the pressure value in the vacuum apparatus corresponding to the heating power by the measured resistance change.

  Since it is measured as the temperature change of the sensor material, it can be applied not only to vacuum gauges but also to a wide range of fields. For example, in fields such as infrared sensors, gas flow velocity / flow meter sensors, moisture measurement sensors, etc., it is also effective for installation in a narrow space, which is difficult with the conventional type, and for detecting minute temperature changes.

DESCRIPTION OF SYMBOLS 1 Micro pressure sensor 2 Pressure sensor part 21 Polymer film 22 Pressure sensor 221, 222 Electrode 23 Temperature sensor 231, 232 Electrode 24 Polymer film support body 25 Cavity part 26 Adhesive 3 Control part 31 Pressure sensor drive part 32 Temperature measurement part 33 Temperature Correction Unit 34 Display Unit 4 Lead Wire 5 P Gas Molecule

Claims (4)

A micro pressure sensor comprising a pressure sensor unit 2 of a heat conduction drive type disposed at a required location in a vacuum apparatus and a control unit 3 disposed outside the vacuum apparatus,
The pressure sensor unit 2 includes a polymer film support 24 formed of a bottom surface and a cylindrical or square frame and having a cavity 25, and the polymer film 21 is bonded to the upper surface of the frame of the polymer film support 24. The pressure sensor 22 is attached to the central portion of the polymer film 21, and one or a plurality of temperature sensors 23 are provided around the pressure sensor 22. Are respectively connected to the control unit 3 via electrodes,
The control unit 3 applies heating power to the pressure sensor 22 to control heating to a constant temperature, measures the temperature around the pressure sensor 22 with the temperature sensor 23 by a resistance change, and vacuum corresponding to the heating power by the measured resistance change. A micro pressure sensor characterized in that an accurate pressure value in a vacuum apparatus is measured by correcting a pressure value in the apparatus.   2. The micro pressure sensor according to claim 1, wherein the pressure sensor is a tantalum-aluminum composite nitride.   The lower portion of the polymer film 21 on which the pressure sensor 22 is mounted is a hollow portion 25 of the polymer film support 24, thereby reducing the heat capacity and improving the pressure sensor 22 sensitivity and responsiveness. The micro pressure sensor according to claim 1 or 2.   The micro pressure sensor according to any one of claims 1 to 3, wherein the material of the polymer film 21 is polyimide.

Images