Method for calibrating vacuum gauge

Abstract

The invention discloses a method for calibrating a vacuum gauge, and the method comprises the steps: providing a chamber with a fixed volume, and enabling a gas inlet of the chamber to be connected with a gas mass flow controller; zero calibration is carried out on the vacuum gauge to be calibrated installed on the cavity; gas is introduced into the chamber at a preset flow through the gas mass flow controller, the reading of the to-be-calibrated vacuum gauge changing along with time is recorded, the corresponding pressure in the chamber changing along with time is calculated, and the reading of the to-be-calibrated vacuum gauge is calibrated according to the calculated pressure in the chamber. The chamber with the fixed volume is provided, the vacuum gauge is subjected to zero calibration, the reading of the to-be-calibrated vacuum gauge changing along with time is recorded, the corresponding pressure in the chamber changing along with time is calculated, the reading of the to-be-calibrated vacuum gauge is calibrated, the calibration steps are simple, operability is high, and the calibration precision is high. And point-by-point calibration can be carried out on the vacuum gauge to be calibrated.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor equipment, and in particular to a method for calibrating a vacuum gauge. Background Art

[0002] The vacuum gauge in the semiconductor equipment needs to be calibrated after being used for a period of time. The traditional vacuum gauge calibration method adopts the standard vacuum gauge method, but this calibration method has high requirements for the standard vacuum gauge and cannot calibrate the standard vacuum gauge. At the same time, it is impossible to calibrate the vacuum gauge point by point. The existing calibration method will introduce the King vacuum gauge into the semiconductor equipment to calibrate the original vacuum gauge. The calibration steps are cumbersome and the operability is poor. Therefore, a method that is simple to operate and can realize point-by-point calibration of the vacuum gauge is needed. Not only that, in the prior art, calibrating the vacuum gauge sometimes requires removing the vacuum gauge from the semiconductor equipment, which will affect the normal operation of the semiconductor equipment. Summary of the invention

[0003] The purpose of the present invention is to provide a method for calibrating a vacuum gauge, aiming to solve the problems of cumbersome calibration steps, poor operability, inability to calibrate in situ, and inability to calibrate the vacuum gauge point by point in the prior art.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] The present invention provides a method for calibrating a vacuum gauge, comprising the steps of:

[0006] S1. Provide a chamber of fixed volume, wherein the gas inlet of the chamber is connected to a gas mass flow controller;

[0007] S2, zeroing the vacuum gauge to be calibrated installed in the chamber;

[0008] S3. Introduce gas into the chamber at a predetermined flow rate through the gas mass flow controller, record the reading of the vacuum gauge to be calibrated as it changes with time, calculate the pressure in the chamber corresponding to the change with time, and calibrate the reading of the vacuum gauge to be calibrated according to the calculated pressure in the chamber.

[0009] Preferably, in step S1, the air outlet of the provided chamber is connected to an air pump, and a valve is provided between the air pump and the air outlet.

[0010] Preferably, in step S2, the zeroing of the vacuum gauge to be calibrated installed on the chamber includes: setting the gas flow rate introduced by the gas mass flow controller to zero, opening the valve, and the vacuum pump evacuating the chamber to the ultimate vacuum to achieve zeroing.

[0011] Preferably, the step S1 includes obtaining the volume of the chamber.

[0012] Preferably, in step S3, the calculation of the pressure in the chamber corresponding to the change over time includes:

[0013] obtaining an initial pressure in the chamber;

[0014] The valve is closed, and gas is introduced into the chamber at a predetermined flow rate through the gas mass flow controller. The pressure in the chamber corresponding to the change over time is calculated based on the initial pressure and the volume of the chamber.

[0015] Preferably, the method of obtaining the initial pressure in the chamber includes: opening the valve, pumping out the pressure with the vacuum pump, introducing gas into the chamber at a predetermined flow rate through the gas mass flow controller, and after the pressure in the chamber stabilizes, the indication of the vacuum gauge to be calibrated is used as the initial pressure.

[0016] Preferably, the calculation formula for calculating the pressure in the chamber corresponding to the change over time based on the initial pressure and the volume of the chamber is:

[0017]

[0018] Wherein, P represents the calculated pressure in the chamber, P0 represents the initial pressure, R represents a constant, Q1 represents the predetermined flow rate, T represents a temperature value, t represents time, and V represents the volume of the chamber.

[0019] Preferably, in step S3, calibrating the indication of the vacuum gauge to be calibrated includes: selecting multiple time points, and calibrating the vacuum gauge to be calibrated multiple times according to the pressure in the chamber calculated at each time point and the indication of the vacuum gauge to be calibrated at the corresponding time point.

[0020] Preferably, the method of obtaining the volume of the chamber includes: providing an accurate vacuum gauge, introducing a certain flow rate of gas into the chamber, and calculating the volume of the chamber according to the measurement value of the accurate vacuum gauge.

[0021] Preferably, the volume V of the chamber is calculated by the following formula:

[0022]

[0023] Wherein, ΔP represents the pressure difference within the chamber within a time period of Δt, Δt represents the time for introducing gas, R represents a constant, Q represents the certain flow rate, and T represents the temperature value.

[0024] Preferably, in the step S1, a flow restrictor is provided between the gas mass flow controller and the chamber to control the stability of the flow rate when the gas is introduced into the chamber.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a method for calibrating a vacuum gauge, by providing a chamber of fixed volume, zeroing the vacuum gauge, recording the reading of the vacuum gauge to be calibrated when it changes with time, and calculating the pressure in the chamber corresponding to the change with time, so as to calibrate the reading of the vacuum gauge to be calibrated. The present invention has simple calibration steps and strong operability, and can calibrate the vacuum gauge to be calibrated point by point; at the same time, it can realize in-situ non-disassembly calibration without affecting the operation of semiconductor equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are an embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0028] Figure 1 An application principle diagram of a method for calibrating a vacuum gauge provided in one embodiment of the present invention;

[0029] Figure 2 A schematic diagram of a structure of an epitaxial device using a method for calibrating a vacuum gauge provided in an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the structure of a current limiter provided in one embodiment of the present invention.

[0031] Explanation of the reference numerals: 101 - restrictor, 102 - valve, 103 - vacuum gauge to be calibrated, 104 - temperature measuring device, 105 - chamber, 106 - gas mass flow controller, 107 - vacuum pump, 108 - first switch valve, 109 - second switch valve, 110 - epitaxial device. DETAILED DESCRIPTION

[0032] The following is combined with Figure 1-3The method for calibrating a vacuum gauge proposed in the present invention is further described in detail with specific implementation methods. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the drawings are in a very simplified form and are not in precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the implementation methods of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed in the present invention.

[0033] In view of the problems in the prior art of calibrating a vacuum gauge, the calibration steps are complicated, the operability is poor, and the vacuum gauge cannot be calibrated point by point.

[0034] This embodiment provides a method for calibrating a vacuum gauge, comprising the following steps:

[0035] Step S1: Reference Figure 1 As shown, a chamber 105 of a fixed volume is provided, and the volume of the chamber 105 is obtained, and the air inlet of the chamber 105 is connected to a gas mass flow controller (Mass Flow Controller, MFC) 106; the air outlet of the provided chamber 105 is connected to a vacuum pump 107, and a valve 102 is provided between the vacuum pump 107 and the air outlet, and a solenoid valve is selected in this example. At the same time, a flow restrictor 101 is provided between the gas mass flow controller 106 and the chamber 105 to control the stability of the flow when the gas is passed into the chamber 105. A temperature measuring device 104 is also installed on the chamber 105, which is used to measure the temperature in the chamber 105; a vacuum gauge 103 is also installed on the chamber 105, which is used to measure the pressure in the chamber.

[0036] In this embodiment, the method of obtaining the volume of the chamber 105 includes: providing an accurate vacuum gauge, introducing a certain flow of gas into the chamber 105, and calculating the volume of the chamber 105 according to the measurement value of the accurate vacuum gauge. The volume V of the chamber 105 is calculated by the following formula:

[0037]

[0038] In formula (1), ΔP represents the pressure difference within the chamber 105 within a time period of Δt, which is measured by the vacuum gauge 103; Δt represents the time for introducing gas, R represents a constant, Q represents the certain flow rate, and T represents the temperature value, which is measured by the temperature measuring device 104.

[0039] In step S1 , the vacuum gauge 103 is accurate, but the vacuum gauge 103 will become inaccurate after being used for a period of time and needs to be calibrated.

[0040] Step S2, zeroing the vacuum gauge 103 to be calibrated installed on the chamber 105, which specifically includes: setting the gas flow rate introduced by the gas mass flow controller 106 to zero, opening the valve 102, and the vacuum pump 107 evacuating the chamber 105 to the ultimate vacuum to achieve zeroing.

[0041] Step S3, the vacuum gauge 103 to be calibrated, which is arranged on the chamber 105, is introduced into the chamber 105 at a predetermined flow rate (which may be different from the certain flow rate described above) through the gas mass flow controller 106, and the reading of the vacuum gauge 103 to be calibrated is recorded as it changes with time, and the corresponding pressure in the chamber 105 as it changes with time is calculated, and the reading of the vacuum gauge 103 to be calibrated is calibrated according to the calculated pressure in the chamber 105. The calculation of the corresponding pressure in the chamber 105 as it changes with time includes:

[0042] Step S3.1, obtaining the initial pressure in the chamber 105; opening the valve 102, the vacuum pump 107 evacuates the pressure, and the gas is introduced into the chamber 105 at a predetermined flow rate through the gas mass flow controller 106. After the pressure in the chamber 105 stabilizes, the reading of the vacuum gauge 103 to be calibrated is used as the initial pressure.

[0043] Step S3.2, close the valve 102, introduce gas into the chamber 105 at a predetermined flow rate through the gas mass flow controller 106, and calculate the corresponding pressure in the chamber 105 as it changes over time based on the initial pressure and the volume of the chamber 105.

[0044] The calculation formula for calculating the pressure in the chamber 105 corresponding to the change over time according to the initial pressure and the volume of the chamber 105 is:

[0045]

[0046] In formula (2), P represents the calculated pressure in the chamber 105, P0 represents the initial pressure, R represents a constant, Q1 represents the predetermined flow rate, T represents a temperature value measured by the temperature measuring device 104, t represents time, and V represents the volume of the chamber 105.

[0047] Optionally, multiple time points may be selected, and the vacuum gauge 103 to be calibrated may be calibrated multiple times according to the pressure in the chamber 105 calculated at each time point and the reading of the vacuum gauge 103 to be calibrated at the corresponding time point.

[0048] The above-mentioned method for calibrating a vacuum gauge can be applied to semiconductor equipment, such as at least one of CVD (Chemical Vapor Deposition) equipment, etching equipment, epitaxial equipment, and RTP (rapid thermal processing) equipment. The semiconductor equipment is used for processing wafers, such as etching wafers, growing thin films on wafers, or annealing.

[0049] The method for calibrating the vacuum gauge is specifically introduced below using a specific embodiment applied to the epitaxial device 110:

[0050] refer to Figure 2 As shown, the chamber of the epitaxial device 110 is used as the chamber 105 of fixed volume in the above method. The epitaxial device 110 includes a heating device, a gas source, a chamber, a gas mass flow controller 106, a valve 102, a temperature measuring device 104, a vacuum gauge 103 and an exhaust pump 107. The chamber has a base, an upper dome, a lower dome, and a rotating support. The upper and lower domes are made of transparent quartz material to form a sealed chamber. The base is arranged in the chamber for carrying the wafer to be processed, and the rotating support is used to support the rotation and lifting of the base. An air inlet is arranged on one side of the chamber, and an air outlet is arranged on the other side of the chamber. The air inlet and the air outlet are located oppositely. The air inlet is connected to the gas source through a gas pipeline. The gas mass flow controller 106 is arranged on the gas pipeline. The gas mass flow controller 106 is used to control the flow of the process gas in the chamber during the process, and can also control the flow when calibrating the vacuum gauge 103. The gas outlet is connected to the vacuum pump 107 through an exhaust pipeline, and the valve 102 is arranged between the vacuum pump and the gas outlet, and is arranged on the exhaust pipeline. The gas outlet is provided with a gas outlet nozzle, and the temperature measuring device 104 and the vacuum gauge 103 are arranged on the gas outlet nozzle to measure the temperature and pressure of the chamber. The heating device is arranged above and below the chamber to heat the wafer during the process and provide heat radiation.

[0051] When processing wafers, the process gas is transported from the gas source to the chamber through the gas pipeline, the gas mass flow controller 106 controls the flow of the process gas input into the chamber, and the vacuum gauge 103 monitors the pressure in the chamber in real time. The exhaust pump 107 extracts the post-process process gas out of the chamber through the exhaust pipeline.

[0052] After long-term use, the vacuum gauge 103 may become inaccurate and needs to be calibrated. The calibration can be performed by calibrating the vacuum gauge 103 in situ using the above method.

[0053] First, the volume of the epitaxial device 110 is obtained before calibration. When the vacuum gauge is accurate, a certain flow rate Q of gas is introduced into the epitaxial device 110. According to the measurement value of the accurate vacuum gauge and the calculation formula shown in the above formula (1), the volume V of the inner cavity of the epitaxial device 110 is calculated.

[0054] Secondly, before calibrating the vacuum gauge 103 to be calibrated, it is necessary to zero the vacuum gauge 103 to be calibrated, set the gas flow rate introduced by the gas mass flow controller 106 to zero, open the valve 102, and the vacuum pump 107 continuously extracts gas from the inner cavity of the epitaxial device 110 to the ultimate vacuum to achieve zeroing.

[0055] Finally, during calibration, the initial pressure P0 in the epitaxial device 110 is first obtained, and the specific steps are as follows: open the valve 102, the vacuum pump 107 is used to extract the pressure, and the gas is introduced into the epitaxial device 110 at a predetermined flow rate Q1 through the gas mass flow controller 106. After the pressure in the epitaxial device 110 is stabilized, the reading of the vacuum gauge 103 to be calibrated is used as the initial pressure P0. Close the valve 102, and introduce gas into the epitaxial device 110 at a predetermined flow rate Q1 through the gas mass flow controller 106, record the reading of the vacuum gauge 103 to be calibrated as it changes with time, and calculate the corresponding pressure in the epitaxial device 110 as it changes with time based on the initial pressure P0 and the volume V of the epitaxial device 110, and calibrate the vacuum gauge 103 to be calibrated.

[0056] Preferably, the epitaxial device 110 further includes a flow limiter 101, which is arranged on the gas pipeline. Figure 3As shown, the gas pipeline includes parallel branches, and the branches are two. One group of the two parallel branches is set: the second switch valve 109 and the flow restrictor 101, and the other group of the two parallel branches is set: the first switch valve 108. When processing the wafer (that is, the vacuum gauge is not calibrated), in order to ensure the normal operation of the epitaxial device, the second switch valve 109 is closed and the first switch valve 108 is opened, so that the gas introduced by the gas mass flow controller 106 directly flows into the epitaxial device 110 without flowing through the flow restrictor 101. When calibrating the vacuum gauge, the first switch valve 108 is closed and the second switch valve 109 is opened, and the gas introduced by the gas mass flow controller 106 flows through the flow restrictor 101, and the flow restrictor 101 controls the stability of the flow when the gas is introduced into the epitaxial device 110.

[0057] In summary, the above embodiment provides a method for calibrating a vacuum gauge, by providing a chamber of fixed volume, zeroing the vacuum gauge, recording the reading of the vacuum gauge to be calibrated as it changes with time, and calculating the pressure in the chamber corresponding to the change with time, to calibrate the reading of the vacuum gauge to be calibrated. The method for calibrating the vacuum gauge in this embodiment has simple calibration steps and strong operability, and the vacuum gauge to be calibrated can be calibrated point by point; at the same time, in-situ non-disassembly calibration can be achieved without affecting the operation of the semiconductor equipment.

[0058] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0059] In the description of the present invention, it should be understood that the terms "center", "height", "thickness", "up", "down", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0060] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0062] In addition, the functional modules in the various embodiments of this document may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0063] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for calibrating a vacuum gauge, characterized in that: Includes steps: S1. Provide a chamber of fixed volume, wherein the gas inlet of the chamber is connected to a gas mass flow controller; S2, zeroing the vacuum gauge to be calibrated installed in the chamber; S3. Introduce gas into the chamber at a predetermined flow rate through the gas mass flow controller, record the reading of the vacuum gauge to be calibrated as it changes with time, calculate the pressure in the chamber corresponding to the change with time, and calibrate the reading of the vacuum gauge to be calibrated according to the calculated pressure in the chamber.

2. The method for calibrating a vacuum gauge according to claim 1, characterized in that: In the step S1, the air outlet of the provided chamber is connected to an air pump, and a valve is provided between the air pump and the air outlet.

3. The method for calibrating a vacuum gauge according to claim 2, characterized in that: In the step S2, the zeroing of the vacuum gauge to be calibrated installed on the chamber includes: setting the gas flow rate introduced by the gas mass flow controller to zero, opening the valve, and the vacuum pump evacuating the chamber to the ultimate vacuum to achieve zeroing.

4. The method for calibrating a vacuum gauge according to claim 2, characterized in that: In the step S1, the volume of the chamber is obtained.

5. The method for calibrating a vacuum gauge according to claim 4, characterized in that: In step S3, the calculation of the pressure in the chamber corresponding to the change over time includes: obtaining an initial pressure in the chamber; The valve is closed, and gas is introduced into the chamber at a predetermined flow rate through the gas mass flow controller. The pressure in the chamber corresponding to the change over time is calculated based on the initial pressure and the volume of the chamber.

6. The method for calibrating a vacuum gauge according to claim 5, characterized in that: The obtaining of the initial pressure in the chamber comprises: opening the valve, the vacuum pump evacuating the pressure, introducing gas into the chamber at a predetermined flow rate through the gas mass flow controller, and after the pressure in the chamber stabilizes, the reading of the vacuum gauge to be calibrated is used as the initial pressure.

7. The method for calibrating a vacuum gauge according to claim 6, characterized in that: The calculation formula for calculating the pressure in the chamber corresponding to the change over time based on the initial pressure and the volume of the chamber is: Wherein, P represents the calculated pressure in the chamber, P0 represents the initial pressure, R represents a constant, Q1 represents the predetermined flow rate, T represents a temperature value, t represents time, and V represents the volume of the chamber.

8. The method for calibrating a vacuum gauge according to claim 7, characterized in that: In step S3, calibrating the indication of the vacuum gauge to be calibrated includes: selecting multiple time points, and calibrating the vacuum gauge to be calibrated multiple times according to the pressure in the chamber calculated at each time point and the indication of the vacuum gauge to be calibrated at the corresponding time point.

9. The method for calibrating a vacuum gauge according to claim 4, characterized in that: The obtaining of the volume of the chamber includes: providing an accurate vacuum gauge, introducing a certain flow of gas into the chamber, and calculating the volume of the chamber according to the measurement value of the accurate vacuum gauge.

10. The method for calibrating a vacuum gauge according to claim 9, characterized in that: The volume V of the chamber is calculated by the following formula: Wherein, ΔP represents the pressure difference within the chamber within a time period of Δt, Δt represents the time for introducing gas, R represents a constant, Q represents the certain flow rate, and T represents the temperature value.

11. The method for calibrating a vacuum gauge according to claim 1, characterized in that: In the step S1, a flow restrictor is provided between the gas mass flow controller and the chamber to control the stability of the flow rate of the gas when it is introduced into the chamber.

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