A wide-range thin-film vacuum gauge

Abstract

This invention discloses a wide-range thin-film vacuum gauge, comprising a housing, within which a detection electrode is disposed, dividing the interior of the housing into a detection chamber and a vacuum chamber. The detection chamber is connected to an inlet pipe, and the vacuum chamber is connected to a pumping pipe. A piezoresistive element is disposed within the vacuum chamber, arranged parallel to the detection electrode. A fixed electrode is plated on the side of the piezoresistive element opposite to the detection electrode. Four equal-value resistors are integrated on the piezoresistive element and connected to form a Wheatstone bridge. The fixed electrode and the Wheatstone bridge are led out of the vacuum chamber via lead wires and connected to an external testing circuit. The thin-film vacuum gauge disclosed in this invention can achieve measurements in the low to medium vacuum range, retaining the high sensitivity of the vacuum gauge in the medium vacuum range, and effectively widening the measurement range of the capacitive thin-film vacuum gauge.

Description

Technical Field

[0001] This invention relates to the field of vacuum gauge technology, and in particular to a wide-range thin-film vacuum gauge. Background Technology

[0002] With the continuous advancement of science and technology, many high-tech fields require extremely high vacuum environments. Especially in semiconductor manufacturing, many processes, such as etching and deposition, need to be performed under high vacuum conditions. Thin-film vacuum gauges are direct vacuum gauges that utilize the principle of elastic deformation of an elastic thin film under pressure difference. They can measure vacuum levels from 1 to 10... 5 Medium and low vacuum pressure measurements are performed within the range of Pa.

[0003] Vacuum gauges can be classified into piezoelectric, piezoresistive, and capacitive types based on the different methods of transmitting deformation and electrical signals. Piezoresistive thin-film vacuum gauges utilize the piezoresistive effect of semiconductor materials, forming a Wheatstone bridge through interconnected piezoresistors located on the sensitive thin film, converting the vacuum environment pressure into an electrical signal to measure low vacuum pressure. Capacitive thin-film vacuum gauges utilize the deformation of a metal thin film under pressure, causing a change in capacitance of a sensitive capacitor composed of the metal thin film and fixed electrodes. This capacitance change is read through an external circuit to measure the external vacuum pressure.

[0004] To achieve high sensitivity and large capacitance, existing capacitive thin-film vacuum gauges employ extremely small film thicknesses and capacitor spacing, thus limiting their ability to measure low vacuums of a few kPa. Piezoresistive vacuum gauges, on the other hand, have their piezoresistors distributed on a silicon wafer film. When the film thickness is large, the piezoresistive vacuum gauge has low sensitivity to vacuums between 1 Pa and 1 kPa and exhibits significant errors. Conversely, when the film thickness is thin, its linearity deteriorates.

[0005] To address the aforementioned problems, it is necessary to propose a wide-range thin-film vacuum gauge that is reasonably designed and can effectively solve these problems. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a wide-range thin-film vacuum gauge, which effectively increases the measurement range of the thin-film vacuum gauge while ensuring its sensitivity and linearity.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A wide-range thin-film vacuum gauge includes a housing. A detection electrode is disposed within the housing, dividing the interior of the housing into a detection chamber and a vacuum chamber. The detection chamber is connected to an inlet pipe, and the vacuum chamber is connected to a suction pipe. A piezoresistive element is disposed within the vacuum chamber, arranged parallel to the detection electrode. A fixed electrode is plated on the side of the piezoresistive element opposite to the detection electrode. Four equal-value resistors are integrated on the piezoresistive element and connected to form a Wheatstone bridge. The fixed electrode and the Wheatstone bridge are led out of the vacuum chamber via lead wires and connected to an external testing circuit.

[0009] In the above scheme, the detection electrode is made of nickel-based alloy, stainless steel or phosphor bronze.

[0010] In the above scheme, the piezoresistive element is a silicon wafer thin film, and four equivalent resistors are integrated on the silicon wafer thin film using the diffusion process of integrated circuits.

[0011] In a further technical solution, the silicon wafer film is made into a silicon ring that is thin in the middle and thick at the edges by means of mechanical processing and chemical etching.

[0012] In the above scheme, the material of the fixed electrode is gold or aluminum.

[0013] In the above scheme, a filter screen is provided at the connection between the air inlet pipe and the detection chamber.

[0014] In the above scheme, a getter is provided in the vacuum chamber, and the getter is fixed on the inner wall of the shell.

[0015] In the above scheme, the shell is made of nickel-based alloy material.

[0016] In the above scheme, the lead wires include five wires: one wire connected to the fixed electrode, two wires connected to the two ends of the Wheatstone bridge, and two wires connected to the middle of the Wheatstone bridge.

[0017] Through the above technical solution, the wide-range thin-film vacuum gauge provided by the present invention has the following beneficial effects:

[0018] The present invention provides a wide-range thin-film vacuum gauge that uses a piezoresistive element instead of the existing fixed electrode plate. When the pressure difference between the vacuum chamber and the detection chamber is large, the detection electrode contacts the fixed electrode and applies pressure to the piezoresistive element. The vacuum level is measured by measuring the change in resistance of the piezoresistive element. When the pressure difference between the two chambers is small, the detection electrode and the fixed electrode form a variable capacitor. The vacuum level is measured by measuring the size of the variable capacitor.

[0019] This invention enables thin-film vacuum gauges to perform measurements in the low to medium vacuum range, retains the high sensitivity of the vacuum gauge in the medium vacuum range, and effectively expands the measurement range of capacitive thin-film vacuum gauges. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0021] Figure 1 This is a schematic diagram of a wide-range thin-film vacuum gauge structure disclosed in an embodiment of the present invention;

[0022] Figure 2 This is a planar schematic diagram of a piezoresistive element;

[0023] Figure 3 This is a schematic diagram of a Wheatstone bridge.

[0024] In the diagram, 1 is the housing; 2 is the detection electrode; 3 is the fixed electrode; 4 is the piezoresistive element; 5 is the vacuum chamber; 6 is the detection chamber; 7 is the air inlet pipe; 8 is the air extraction pipe; 9 is the degassing agent; 10 is the lead wire; 11 is the filter screen; and 12 is the resistor. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] This invention provides a wide-range thin-film vacuum gauge, such as... Figure 1 As shown, the system includes a housing 1 made of a nickel-based alloy to provide better corrosion resistance for the entire vacuum gauge, enabling its application in harsh corrosive environments. A detection electrode 2 is disposed within the housing 1. The detection electrode 2 is made of a thin film of nickel-based alloy, stainless steel, or phosphor bronze, and its edges are sealed and fixed to the inner wall of the housing 1. This divides the interior of the housing 1 into a detection chamber 6 and a vacuum chamber 5.

[0027] A piezoresistive element 4 is installed inside the vacuum chamber 5. The piezoresistive element 4 is a silicon wafer thin film, and the edges of the film are fixed to the inner wall of the housing 1. The silicon wafer thin film is made into a silicon ring with a thin center and thick edges by mechanical processing and chemical etching, which can improve the deformation of the middle of the film.

[0028] The piezoresistive element 4 is arranged parallel to the detection electrode 2, and a fixed electrode 3 is plated on the side of the piezoresistive element 4 opposite to the detection electrode 2. Figure 2 As shown, the fixed electrode 3 is located in the central region of the silicon wafer thin film. The material of the fixed electrode 3 is generally gold or aluminum, but other materials with good conductivity can also be selected. Four equivalent resistors 12 are integrated onto the silicon wafer thin film around the fixed electrode 3 using integrated circuit diffusion technology and connected as shown. Figure 3 The Wheatstone bridge shown.

[0029] The fixed electrode 3 and the Wheatstone bridge are led out of the vacuum chamber 5 through lead wires 10 and connected to the external test circuit. Lead wires 10 include five wires: one wire connects to the fixed electrode 3, two wires connect to the two ends (end A and end B) of the Wheatstone bridge, and two wires connect to the middle (end C and end D) of the Wheatstone bridge for measuring the pressure difference.

[0030] The detection chamber 6 is connected to the air inlet pipe 7 to allow the gas to be tested to be introduced into the detection chamber 6. In order to filter out particles and contaminants in the gas to be tested and prevent them from adhering to the detection electrode 2 and causing deformation or damage to the detection electrode 2, a filter screen 11 is provided at the connection between the air inlet pipe 7 and the detection chamber 6. The filter screen 11 can be made of polytetrafluoroethylene, or other materials can be selected according to actual needs.

[0031] Vacuum chamber 5 is connected to pumping pipe 8; vacuum chamber 5 is a fully sealed structure and maintains a high vacuum state. Pumping pipe 8 is connected to vacuum chamber 5. Generally, pumping pipe 8 is connected to a vacuum pump outside vacuum chamber 5, and vacuum chamber 5 is maintained in a vacuum state by pumping air out of vacuum chamber 5. In specific implementation, in order to eliminate residual gas in vacuum chamber 5 and maintain a high vacuum level in vacuum chamber 5 for a long time, a degassing agent 9 is also provided on the inner wall of the shell 1 of vacuum chamber 5, thereby improving the stability of vacuum gauge. The type of degassing agent 9 can be selected according to actual needs, and the present invention does not limit it.

[0032] When the gas to be detected is introduced into the detection chamber 6, if the gas is a low-vacuum pressure gas, the detection electrode 2 will be subjected to greater pressure and undergo greater deformation. The deformed detection electrode 2 bends and applies pressure to the piezoresistive element 4. The low-vacuum level is measured by measuring the change in resistance on the piezoresistive element 4 through the lead wire 10. If the gas to be detected is a medium-vacuum pressure, the atmospheric pressure on the detection electrode 2 is insufficient to make the detection electrode 2 contact the piezoresistive element 4. The detection electrode 2 and the fixed electrode 3 form a variable capacitor. The medium-vacuum level can be measured by measuring the change in capacitance of the variable capacitor through the lead wire 10. Thus, this invention replaces the substrate supporting the fixed electrode 3 with the piezoresistive element 4, enabling the vacuum gauge to measure in the low-vacuum range. The distance between the detection electrode 2 and the fixed electrode 3 can be set very small, greatly increasing the initial capacitance of the variable capacitor, thereby improving the sensitivity and resolution of the vacuum gauge in the medium-vacuum range.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wide range thin film gauge, characterized in that, The application relates to a sensor, which comprises a shell, a detection electrode arranged in the shell, a detection chamber and a vacuum chamber formed by the detection electrode in the shell, an air inlet pipe connected to the detection chamber, a vacuum pipe connected to the vacuum chamber, a piezoresistance element arranged in the vacuum chamber, a fixed electrode plated on the side of the piezoresistance element opposite to the detection electrode, four equal resistors integrated on the piezoresistance element and connected in parallel to form a Wheatstone bridge, and an external test circuit connected to the fixed electrode and the Wheatstone bridge through lead-out wires.

2. A wide range thin film gauge as claimed in claim 1, wherein, The detection electrode is made of nickel-based alloy, stainless steel or phosphor bronze.

3. A wide range thin film gauge as claimed in claim 1, wherein, The piezoresistance element is a silicon wafer film, and four equal resistors are integrated on the silicon wafer film by a diffusion process of an integrated circuit.

4. A wide range thin film gauge as claimed in claim 3, wherein, The silicon wafer film is made into a silicon ring with a thin middle and thick edges by a mechanical processing and chemical corrosion method.

5. A wide range thin film gauge as claimed in claim 1, wherein, The fixed electrode is made of gold or aluminum.

6. A wide range thin film gauge as claimed in claim 1, wherein, A filter screen is arranged at the joint of the air inlet pipe and the detection chamber.

7. A wide range thin film gauge as claimed in claim 1, wherein, An air suction agent is arranged in the vacuum chamber and fixed on the inner wall of the shell.

8. A wide range thin film gauge as defined in claim 1 wherein, The shell is made of nickel-based alloy.

9. A wide range thin film gauge as claimed in claim 1, wherein, The lead-out wires include five wires, one of which is connected to the fixed electrode, two of which are connected to two ends of the Wheatstone bridge, and the other two of which are connected to the middle of the Wheatstone bridge.

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