CN115148567A - Vacuum system of scanning electron microscope and control method thereof - Google Patents
Vacuum system of scanning electron microscope and control method thereof Download PDFInfo
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- CN115148567A CN115148567A CN202210772944.5A CN202210772944A CN115148567A CN 115148567 A CN115148567 A CN 115148567A CN 202210772944 A CN202210772944 A CN 202210772944A CN 115148567 A CN115148567 A CN 115148567A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/18—Vacuum locks ; Means for obtaining or maintaining the desired pressure within the vessel
- H01J37/185—Means for transferring objects between different enclosures of different pressure or atmosphere
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
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Abstract
The invention discloses a vacuum system of a scanning electron microscope and a control method thereof, wherein the vacuum system comprises: the sample chamber is connected with an air source control part which supplies air to the sample chamber; the objective lens air gap interlayer is communicated with the sample chamber; the electron gun is communicated with the objective lens air gap interlayer and is used for emitting electron beams; the shunting type molecular pump is provided with a main air suction port and a shunting air suction port, the main air suction port is connected with the electron gun, and the shunting air suction port is connected with the objective lens air gap interlayer; the mechanical pump, the pump mouth intercommunication of mechanical pump has first pipeline, and first pipeline intercommunication sample room is equipped with first vacuum isolation valve on the first pipeline, and mechanical pump often keeps opening state. The vacuum system of the scanning electron microscope has low energy consumption and low cost, and simultaneously, the vacuum degree in the sample chamber can be maintained in a certain range and the vacuum degree can be rapidly and stably changed.
Description
Technical Field
The invention relates to the field of scanning electron microscopes, in particular to a vacuum system of a scanning electron microscope and a control method thereof.
Background
The sample chamber of the scanning electron microscope is a chamber for placing a sample to be observed, and under normal conditions, the vacuum in the sample chamber, the vacuum in the electron gun and the vacuum in the lens barrel are consistent and are all pumped to a high vacuum state through a vacuum obtaining equipment system, so that the sample to be observed is usually only limited to a sample which can conduct electricity and does not volatilize gas. Therefore, the samples are usually pretreated by dehydration, drying, freezing or surface spraying, and can be analyzed in an electron microscope, but the original real appearance of the water-containing samples cannot be directly observed. If the vacuum degree of the sample chamber can be reduced and can be manually controlled, the vacuum degree can be freely set and maintained in a certain low vacuum area, and the sample chamber can be applied to the observation and analysis of the samples containing water and nonconducting samples.
In the prior art, a mechanical pump and a diffusion pump or a molecular pump are used as an electron gun and a high-vacuum obtaining and maintaining pump set in a lens cone, a sandwich mechanical pump is used for pumping out vacuum interlayer gas between the electron lens cone and a sample chamber, and a sample chamber mechanical pump is used for pumping out and maintaining gas in the sample chamber to obtain a desired sample chamber vacuum or gas pressure value, so that a three-stage vacuum system is realized. However, the system is complicated in arrangement of a vacuum interlayer, three mechanical pumps need to be carried, the system pipeline is complicated, and meanwhile, the economic cost and the energy consumption of equipment are high.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, an object of the present invention is to provide a vacuum system for a scanning electron microscope and a control method thereof, wherein the vacuum system for a scanning electron microscope has low energy consumption and low cost, and simultaneously the vacuum degree in a sample chamber can be maintained within a certain range and the vacuum degree can be changed rapidly and stably.
In one aspect of the invention, a vacuum system for a scanning electron microscope is provided.
According to an embodiment of the invention, the vacuum system comprises: the gas source control part supplies gas to the sample chamber; the objective lens air gap interlayer is communicated with the sample chamber; the electron gun is communicated with the objective lens air gap interlayer and is used for emitting electron beams; the shunting type molecular pump is provided with a main air pumping port and a shunting air pumping port, the main air pumping port is connected with the electron gun, and the shunting air pumping port is connected with the objective lens air gap interlayer; the mechanical pump, the pump mouth intercommunication of mechanical pump has first pipeline, first pipeline intercommunication the sample room, be equipped with first vacuum isolation valve on the first pipeline, mechanical pump often keeps in the open mode.
According to the vacuum system of the scanning electron microscope, the vacuum system comprises a sample chamber, an objective lens air gap interlayer, an electron gun, a split-flow type molecular pump and a mechanical pump, the sample chamber is connected with an air source control piece and is communicated with a pump port of the mechanical pump through a first pipeline, a first vacuum isolation valve is arranged on the first pipeline, the sample chamber is communicated with the objective lens air gap interlayer, the objective lens air gap interlayer is communicated with the electron gun, a main air suction port of the split-flow type molecular pump is connected with the electron gun, and a split-flow air suction port is connected with the objective lens air gap interlayer, so that the vacuum degree in the sample chamber can be maintained in a certain range, and the vacuum degree can be changed rapidly and stably.
In some embodiments of the present invention, the first and second, the vacuum system of the scanning electron microscope further comprises: the buffer chamber is communicated with the split-flow molecular pump, the buffer chamber is communicated with a first vacuum gauge, and a second pipeline communicated with the first pipeline is arranged on the buffer chamber; a surge chamber valve disposed on the second conduit, the surge chamber valve being always maintained in an open state.
In some embodiments, a third pipeline is arranged between the main extraction opening and the electron gun, a second vacuum gauge is arranged on the third pipeline, the detection precision of the second vacuum gauge is higher than that of the first vacuum gauge, and the second vacuum gauge is in communication connection or electric connection with the first vacuum gauge and is turned on or turned off according to the detection result of the first vacuum gauge.
In some embodiments, a fourth pipeline communicated with the first pipeline is arranged on the third pipeline, and a second vacuum isolation valve is arranged on the fourth pipeline.
In some embodiments, a fifth pipeline is arranged between the sample chamber and the air source control part, and a third vacuum isolation valve is arranged on the fifth pipeline.
In some embodiments, the sample chamber is communicated with a quick air inlet valve, an air release valve and a third vacuum gauge, and the third vacuum gauge is in communication connection or electric connection with the air source control part so as to control the air source control part to work.
In some embodiments, a sixth pipeline is disposed between the shunt pumping port and the objective lens air gap interlayer, and a fourth vacuum isolation valve is disposed on the sixth pipeline.
In a second aspect of the present invention, the present invention provides a method for controlling a vacuum system of a scanning electron microscope, including the above vacuum system of a scanning electron microscope, the method includes: the first vacuum isolating valve is opened and is closed after the mechanical pump pumps the sample chamber to a first preset air pressure; the shunting type molecular pump pumps and maintains vacuum in the objective lens air gap interlayer and the electron gun; and the gas source control piece is opened to supply gas into the sample chamber.
According to the control method of the vacuum system of the scanning electron microscope, the vacuum system of the scanning electron microscope comprises the steps of opening the first vacuum isolating valve, mechanically pumping gas in the sample chamber, closing the sample chamber after the gas pressure in the sample chamber reaches the first preset gas pressure, then opening the flow-dividing type molecular pump to obtain and maintain a high vacuum environment required in the electron gun, effectively pumping the gas in the sample chamber, then opening the gas source control part, and supplying gas to the sample chamber, so that in the vacuum system of the scanning electron microscope controlled by the method, the vacuum degree in the sample chamber can be maintained in a certain range, and the vacuum degree can be rapidly and stably changed.
In some embodiments, the vacuum system further comprises a buffer chamber communicating the split molecular pump and the mechanical pump; the method further comprises the following steps: when the air pressure in the sample chamber needs to be reduced, the conduction between the buffer chamber and the mechanical pump is cut off, and the first vacuum isolation valve is opened; after the mechanical pump pumps the sample chamber to a second preset air pressure, closing the first vacuum isolation valve; and recovering the conduction of the buffer chamber and the mechanical pump, and pumping and maintaining the vacuum in the objective lens air gap interlayer and the electron gun by the shunt type molecular pump.
In some embodiments, the control method of the vacuum system further includes: and detecting the vacuum degree in the buffer chamber in real time, and starting to detect the vacuum degree in the electron gun if the vacuum degree in the buffer chamber reaches a set value.
In some embodiments, the main pumping port of the split-flow molecular pump is communicated with the pumping pipeline of the mechanical pump, and the first vacuum isolation valve is opened and closed after the mechanical pump pumps the sample chamber to a preset air pressure: when the first vacuum isolating valve is opened, the main air suction port is communicated with an air suction pipeline of the mechanical pump; and when the first vacuum isolation valve is closed, the main extraction opening is cut off from the air extraction pipeline of the mechanical pump.
In some embodiments, the step of the split-flow molecular pump drawing and maintaining a vacuum within the objective lens airgap interlayer and the electron gun further comprises: and detecting the vacuum degree in the sample chamber in real time, and controlling the air source control part to work according to a detection result.
In some embodiments, the step of opening the air supply control member and supplying air to the sample chamber, wherein the air supply control member and the sample chamber are normally kept disconnected, further comprises: and communicating the gas source control part with the sample chamber.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic view of a vacuum system of a scanning electron microscope in an embodiment of the invention;
FIG. 2 is a flow chart illustrating a control method of a vacuum system of a scanning electron microscope according to an embodiment of the present invention;
FIG. 3 is a flowchart illustrating a method for controlling a vacuum system of a scanning electron microscope according to another embodiment of the present invention;
FIG. 4 is a flow chart illustrating a control method of a vacuum system of a scanning electron microscope according to another embodiment of the present invention;
fig. 5 is a flowchart illustrating a control method of a vacuum system of a scanning electron microscope according to another embodiment of the present invention.
Reference numerals:
100. a vacuum system;
10. a sample chamber; 101. an air supply control member; 102. a fifth pipeline; 1021. a third vacuum isolation valve; 103. a quick air inlet valve; 104. a deflation valve; 105. a third vacuum gauge;
20. an objective air gap interlayer; 201. a sixth pipeline; 2011. a fourth vacuum isolation valve;
30. an electron gun; 301. a third pipeline; 3011. a second vacuum gauge; 302. a fourth pipe; 3021. a second vacuum isolation valve;
40. a split flow molecular pump; 401. a main air extraction port; 402. a flow-dividing exhaust port; 403. a molecular pump deflation valve;
50. a mechanical pump; 501. a first conduit; 5011. a first vacuum isolation valve;
60. a buffer chamber; 601. a first vacuum gauge; 602. a second conduit; 6021. a surge chamber valve.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "length", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
Furthermore, features defined as "first" and "second" may explicitly or implicitly include one or more of the features for distinguishing between descriptive features, non-sequential, non-trivial and non-trivial.
In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In one aspect of the present invention, a vacuum system 100 for a scanning electron microscope is provided.
Referring to fig. 1, the vacuum system 100 includes, according to an embodiment of the present invention: sample chamber 10, objective air gap sandwich 20, electron gun 30, split molecular pump 40, and mechanical pump 50.
The sample chamber 10 is connected with an air source control part 101, and the air source control part 101 supplies air to the sample chamber 10; the objective lens air gap interlayer 20 is communicated with the sample chamber 10; the electron gun 30 is communicated with the objective lens air gap interlayer 20 and is used for emitting electron beams; the split-flow molecular pump 40 has a main pumping port 401 and a split-flow pumping port 402, the main pumping port 401 is connected to the electron gun 30, and the split-flow pumping port 402 is connected to the objective air gap interlayer 20; the pump port of the mechanical pump 50 is communicated with a first pipeline 501, the first pipeline 501 is communicated with the sample chamber 10, a first vacuum isolation valve 5011 is arranged on the first pipeline 501, and the mechanical pump 50 is always kept in an open state.
It can be understood that, after the mechanical pump 50 extracts the gas in the sample chamber 10, the split-flow molecular pump 40 is responsible for extracting and maintaining the vacuum environment in the electron gun 30 and the objective lens air gap interlayer 20, so that the number of the mechanical pumps 50 can be reduced, the energy consumption and the vibration during the system operation can be reduced, and the adverse effect on the use, analysis and imaging of an electron microscope caused by the large vibration when a plurality of mechanical pumps are adopted can be avoided. And because the objective air gap interlayer 20 is communicated with the sample chamber 10, the split-flow molecular pump 40 can pump out gas in the sample chamber 10 through the split-flow pumping hole 402, and meanwhile, the gas source control part 101 can supply gas into the sample chamber 10, so that variable vacuum in a certain range is maintained in the sample chamber 10. And the mechanical pump 50 is kept in a continuous working state, when the air pressure in the sample chamber 10 needs to be set from high air pressure to low air pressure, the first vacuum isolation valve 5011 on the first pipeline 501 is opened, the mechanical pump 50 pumps the air in the sample chamber 10, and by adopting the continuous working of the mechanical pump 50, the response is rapid and reliable through the electric or pneumatic control mode of the vacuum isolation valve, so that the vacuum system 100 can rapidly respond to the change of the air pressure in the sample chamber 10.
Specifically, the gas supply control 101 may be a mass flow controller or a control needle valve.
According to the vacuum system 100 of the scanning electron microscope of the embodiment of the invention, the sample chamber 10 is connected with the air source control part 101 and is communicated with the pump port of the mechanical pump 50 through the first pipeline 501, the first vacuum isolation valve 5011 is arranged on the first pipeline 501, meanwhile, the sample chamber 10 is communicated with the objective lens air gap interlayer 20, the objective lens air gap interlayer 20 is communicated with the electron gun 30, the main pumping port 401 of the shunting type molecular pump 40 is connected with the electron gun 30, and the shunting pumping port 402 is connected with the objective lens air gap interlayer 20, so that the vacuum degree in the sample chamber 10 can be maintained in a certain range, the vacuum degree can be rapidly and stably changed, and the use, analysis and imaging of the electron microscope can be ensured not to be influenced by large vibration by adopting fewer mechanical pumps 50.
In some embodiments, referring to fig. 1, the vacuum system 100 of the scanning electron microscope further includes a buffer chamber 60 and a buffer chamber valve 6021, the buffer chamber 60 communicates with the split-flow molecular pump 40, the buffer chamber 60 communicates with the first vacuum gauge 601, and the buffer chamber 60 is provided with a second conduit 602 communicating with the first conduit 501; the buffer chamber valve 6021 is provided in the second pipe 602, and the buffer chamber valve 6021 is always kept in an open state. It will be appreciated that the buffer chamber 60 can greatly increase the rise time of the back pressure of the split molecular pump 40, keeping the split molecular pump 40 within the back pressure range for normal operation.
In some embodiments, referring to fig. 1, a third pipeline 301 is disposed between the main pumping hole 401 and the electron gun 30, a second vacuum gauge 3011 is disposed on the third pipeline 301, the detection accuracy of the second vacuum gauge 3011 is greater than that of the first vacuum gauge 601, and the second vacuum gauge 3011 is in communication connection or electrically connected to the first vacuum gauge 601 and is turned on or turned off according to the detection result of the first vacuum gauge 601. Specifically, the split molecular pump 40 and the electron gun 30 are communicated through the third pipe 301, the split molecular pump 40 pumps the gas in the electron gun 30 through the main pumping port 401, the gas is sucked into the split molecular pump 40 through the third pipe 301, and the indication number of the first vacuum gauge 601 is detected through the second vacuum gauge 3011, so as to determine the on or off of the first vacuum gauge 601.
Specifically, the second vacuum gauge 3011 is a high vacuum gauge for detecting a high vacuum value, and the first vacuum gauge 601 is a low vacuum gauge for detecting a low vacuum value, in the prior art, the vacuum gauge itself has a measured ultimate vacuum degree, and different vacuum gauges have different ultimate vacuum degrees, and the higher the ultimate vacuum degree is, the higher the detection precision of the vacuum gauge is, and when the vacuum gauge exceeds its effective detection range, the detection accuracy is reduced.
In the present application, the detection accuracy of the second vacuum gauge 3011 is greater than that of the first vacuum gauge 601, that is, the ultimate vacuum degree of the second vacuum gauge 3011 is better than that of the first vacuum gauge 601.
The accuracy of the first vacuum gauge 601 is reduced below the ultimate vacuum degree thereof, for example, the accuracy of the first vacuum gauge 601 is reduced below the ultimate vacuum degree n Pa (n is a positive number) thereof, which results in insufficient measurement accuracy, when the reading of the first vacuum gauge 601 is reduced to (n + x) Pa (x is a positive number) during detection, the second vacuum gauge 3011 is opened, the ultimate vacuum degree of the second vacuum gauge 3011 is m Pa (m is a positive number), and m is larger than n.
When the reading of the first vacuum gauge 601 decreases to (n + x) Pa (x is a positive number), it indicates that the air pressure at the front end of the split-flow molecular pump 40 has decreased to a certain high vacuum, and the second vacuum gauge 3011 is turned on to detect the accurate value under the high vacuum.
Wherein, the first vacuum gauge 601 can be electrically connected to the split molecular pump 40, or connected to the split molecular pump 40 by communication (e.g. bluetooth, wiFi, 4G/5G), and the first vacuum gauge 601 can suggest a feedback adjustment mechanism with the split molecular pump 40 by detecting the vacuum degree in the electron gun 30.
In some embodiments, referring to fig. 1, a fourth pipe 302 is disposed on the third pipe 301 and communicates with the first pipe 501, and a second vacuum isolation valve 3021 is disposed on the fourth pipe 302. Specifically, when the gas in the electron gun 30 needs to be pre-pumped, the second vacuum isolation valve 3021 on the fourth pipe 302 is opened, and the mechanical pump 50 will pump the gas in the electron gun 30, so as to rapidly reduce the pressure in the electron gun 30.
In some embodiments, referring to FIG. 1, a fifth conduit 102 is disposed between the sample chamber 10 and the gas source control 101, and a third vacuum isolation valve 1021 is disposed on the fifth conduit 102. Specifically, after the gas in the sample chamber 10 is pre-pumped by the mechanical pump 50, the communication path between the mechanical pump 50 and the sample chamber 10 is disconnected, the gas in the sample chamber 10 is pumped at a constant speed by the split-flow molecular pump 40, when a certain vacuum degree is reached in the sample chamber 10, the third vacuum isolation valve 1021 on the fifth pipeline 102 is opened, and the gas source control part 101 can supply gas to the sample chamber 10, so that the vacuum degree in the sample chamber 10 is maintained within a certain range.
In some embodiments, referring to FIG. 1, the sample chamber 10 is in communication with a quick entry valve 103, an escape valve 104, and a third vacuum gauge 105, the third vacuum gauge 105 being in communication with or in electrical communication with the air supply control 101 to control the operation of the air supply control 101. That is, the quick air inlet valve 103, the air outlet valve 104, and the third vacuum gauge 105 are independently connected to the sample chamber 10. Specifically, when a sample is to be taken or replaced from the sample chamber 10, the air pressure in the sample chamber 10 is increased to a level corresponding to the outside air pressure by introducing the outside air through the air release valve 104, so as to open the door of the sample chamber 10 for sampling and replacing. When the vacuum degree in the sample chamber 10 is low and the vacuum degree in the sample chamber 10 needs to be increased rapidly, gas can be introduced through the rapid gas inlet valve 103.
Optionally, a molecular pump deflation valve 403 is arranged on the split molecular pump 40. Specifically, when a sample needs to be taken from the sample chamber 10 or replaced, the operation of the split-flow molecular pump 40 is stopped, and at this time, the molecular pump air release valve 403 is opened, so that the split-flow molecular pump 40 with a higher rotation speed can be stopped as soon as possible, and the sample replacement or the sampling is facilitated.
In some embodiments, referring to fig. 1, a sixth pipe 201 is disposed between the split pumping port 402 and the objective air gap interlayer 20, and a fourth vacuum isolation valve 2011 is disposed on the sixth pipe 201. Specifically, the split-flow molecular pump 40 extracts the gas in the objective air gap interlayer 20 through the split-flow pumping port 402, the objective air gap interlayer 20 is communicated with the sample chamber 10, and the split-flow pumping port 402 can stably extract the gas in the sample chamber 10 by opening the fourth vacuum isolation valve 2011.
An embodiment of a vacuum system 100 for scanning electron microscopy according to the present invention is described below with reference to the drawings.
As shown in fig. 1, a vacuum system 100 for a scanning electron microscope includes: sample chamber 10, objective air gap sandwich 20, electron gun 30, split molecular pump 40, mechanical pump 50, buffer chamber 60, and buffer chamber valve 6021.
The sample chamber 10 is connected with an air source control part 101, the air source control part 101 supplies air to the sample chamber 10, and the air source control part 101 is a mass flow controller; the objective lens air gap interlayer 20 is communicated with the sample chamber 10; the electron gun 30 is communicated with the objective lens air gap interlayer 20 and is used for emitting electron beams; the split-flow molecular pump 40 has a main pumping port 401 and a split-flow pumping port 402, the main pumping port 401 is connected to the electron gun 30, and the split-flow pumping port 402 is connected to the objective air gap interlayer 20; the pump port of the mechanical pump 50 is communicated with a first pipeline 501, the first pipeline 501 is communicated with the sample chamber 10, a first vacuum isolation valve 5011 is arranged on the first pipeline 501, and the mechanical pump 50 is always kept in an open state.
The buffer chamber 60 is communicated with the split-flow molecular pump 40, the buffer chamber 60 is communicated with a first vacuum gauge 601, and a second pipeline 602 communicated with the first pipeline 501 is arranged on the buffer chamber 60; the buffer chamber valve 6021 is provided in the second pipe 602, and the buffer chamber valve 6021 is always kept in an open state.
A third pipeline 301 is arranged between the main extraction opening 401 and the electron gun 30, a second vacuum gauge 3011 is arranged on the third pipeline 301, and the second vacuum gauge 3011 is electrically connected with the first vacuum gauge 601. A fourth pipeline 302 communicated with the first pipeline 501 is arranged on the third pipeline 301, and a second vacuum isolation valve 3021 is arranged on the fourth pipeline 302.
A fifth pipeline 102 is arranged between the sample chamber 10 and the mass flow controller, and a third vacuum isolation valve 1021 is arranged on the fifth pipeline 102. The sample chamber 10 is communicated with a quick air inlet valve 103, an air outlet valve 104 and a third vacuum gauge 105, and the third vacuum gauge 105 is electrically connected with the mass flow controller so as to control the work of the mass flow controller.
A sixth pipeline 201 is arranged between the shunt pumping hole 402 and the objective lens air gap interlayer 20, and a fourth vacuum isolation valve 2011 is arranged on the sixth pipeline 201.
In a second aspect of the present invention, the present invention provides a method for controlling a vacuum system 100 of a scanning electron microscope, including the vacuum system of a scanning electron microscope described above, and referring to fig. 2, the method includes:
s1: first vacuum isolation valve 5011 is opened and closed after mechanical pump 50 pumps sample chamber 10 to a first predetermined pressure.
Specifically, the first preset air pressure may be any value within a range of 20 to 100 Pa.
Referring to the vacuum system 100 of the scanning electron microscope, the vacuum degree and the air pressure in the sample chamber 10 can be measured by the third vacuum gauge 105.
S2: a split-flow molecular pump 40 draws and maintains a vacuum within objective air gap sandwich 20 and electron gun 30.
In this step, specifically, the split-flow molecular pump 40 extracts gas in the electron gun 30 through the main extraction opening 401, the split-flow extraction opening 402 extracts gas in the objective lens air gap interlayer 20, simultaneously detects the vacuum degree in the electron gun 30 in real time, controls the split-flow molecular pump 40 to work according to the detection result, detects the vacuum degree in the sample chamber 10 in real time, and controls the gas source control element 101 to work according to the detection result. Referring to the vacuum system 100 of the scanning electron microscope, the vacuum degree in the electron gun 30 can be measured by the second vacuum gauge 3011, and the vacuum degree and the air pressure in the sample chamber 10 can be measured by the third vacuum gauge 105.
S3: gas supply control 101 is opened to supply gas to sample cell 10.
In this step, specifically, when the second vacuum gauge 3011 detects that the vacuum degree in the electron gun 30 is 0.02 to 0.05Pa, the connection path between the air source control part 101 and the sample chamber 10 is conducted, so that the air source control part 101 supplies air to the sample chamber 10, and at this time, the air pressure value in the sample chamber 10 can be controlled by controlling the flow rate of the air source control part 101 so as to maintain the vacuum degree in the sample chamber 10 within a certain range.
Wherein the range of the vacuum degree in the sample chamber 10 is 5 to 1000Pa. The third vacuum gauge 105 on the sample chamber 10 establishes a negative feedback mechanism with the gas source control 101 and the third vacuum gauge 105. For example, when the sample chamber 10 needs to be set from a low pressure to a high pressure, the air supply control 101 will increase the inlet air flow rate appropriately according to the air pressure monitored by the third vacuum gauge 105, and will quickly stabilize when the set air pressure is reached. It should be noted that the specific type of the air supply control member 101 is the same as that described above, and will not be described herein.
In some embodiments, the vacuum system 100 further comprises a buffer chamber 60, the buffer chamber 60 communicating the split molecular pump 40 and the mechanical pump 50; referring to fig. 3, the method further includes:
s4: when it is desired to reduce the pressure in sample chamber 10, buffer chamber 60 is disconnected from mechanical pump 50, opening first vacuum isolation valve 5011.
S5: after the mechanical pump 50 pumps the sample chamber 10 to the second predetermined pressure, the first vacuum isolation valve 5011 is closed.
The second preset air pressure is any value within 5-1000 Pa.
S6: conduction of the buffer chamber 60 and the mechanical pump 50 is restored; split-flow molecular pump 40 draws and maintains a vacuum within objective air gap sandwich 20 and electron gun 30.
The first vacuum gauge 601 detects the vacuum degree in the buffer chamber 60 in real time, so that the pressure increase in the buffer chamber 60 is kept within the back pressure range of the normal operation of the split molecular pump 40, and if the vacuum degree in the buffer chamber 60 reaches a set value, the vacuum degree in the electron gun 30 starts to be detected.
In some embodiments, referring to fig. 4, the main pumping port 401 of the split-flow molecular pump 40 is communicated with the pumping pipeline of the mechanical pump 50, and the first vacuum isolation valve 5011 is opened and closed after the mechanical pump 50 pumps the sample chamber 10 to the preset air pressure:
s11: when the first vacuum isolation valve 5011 is opened, the main pumping port 401 is communicated with the pumping pipeline of the mechanical pump 50.
S12: when the first vacuum isolation valve 5011 is closed, the main suction port 401 and the suction line of the mechanical pump 50 are disconnected.
In some embodiments, referring to fig. 5, before the step of normally disconnecting the gas source control 101 from the sample chamber 10, and opening the gas source control 101 to supply gas to the sample chamber 10, the method further comprises:
s30: gas supply control 101 and sample chamber 10 are connected.
According to the control method of the vacuum system 100 of the scanning electron microscope of the embodiment of the invention, by opening the first vacuum isolation valve 5011 and the second vacuum isolation valve 3021 while keeping the buffer chamber valve 6021 in the open state, the mechanical pump 50 will draw the gas in the sample chamber 10 and the electron gun 30 and make the gas pressure in the sample chamber 10 reach the first preset gas pressure, then the first vacuum isolation valve 5011 and the second vacuum isolation valve 3021 are closed, the mechanical pump 50 is the backing pump of the split molecular pump 40, then the split molecular pump 40 is opened, the main pumping port 401 of the split molecular pump 40 will draw the gas in the electron gun 30 and maintain the high vacuum environment in the electron gun 30, the split pumping port 402 of the split molecular pump 40 will draw the gas in the objective air gap interlayer 20 and maintain the high vacuum environment in the objective air gap interlayer 20, and the second vacuum gauge 3011 will detect the vacuum degree in the electron gun 30, when the second vacuum gauge 3011 detects that the vacuum degree in the electron gun 30 is 0.02-0.05, the control element 101 and the control the flow rate of the gas source in the sample chamber 10 is controlled by Pa. When the air pressure in the sample chamber 10 needs to be set from low air pressure to high air pressure, the air source control part 101 is used to increase the air inlet flow, so that the air pressure value in the sample chamber 10 can be quickly increased. When the pressure in the sample chamber 10 needs to be set from a high pressure to a low pressure, the first vacuum isolation valve 5011 is opened and the buffer valve 6021 is closed, so that the mechanical pump 50 can rapidly pump the gas in the sample chamber 10 to reduce the pressure in the sample chamber 10. Therefore, in the vacuum system 100 of the scanning electron microscope controlled by the method, the vacuum degree in the sample chamber 10 can be maintained within a certain range and can be rapidly and stably changed.
In the description herein, references to the description of the terms "some embodiments," "optionally," "further," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (13)
1. A vacuum system of a scanning electron microscope, comprising:
the gas source control part supplies gas to the sample chamber;
the objective lens air gap interlayer is communicated with the sample chamber;
the electron gun is communicated with the objective lens air gap interlayer and is used for emitting electron beams;
a split-flow molecular pump having a main pumping port and a split-flow pumping port, the main air exhaust port is connected with the electron gun, and the shunt air exhaust port is connected with the objective lens air gap interlayer;
the mechanical pump, the pump port intercommunication of mechanical pump has first pipeline, first pipeline intercommunication the sample room, be equipped with first vacuum isolation valve on the first pipeline, the mechanical pump often keeps opening the state.
2. The vacuum system for scanning electron microscopy according to claim 1, further comprising:
the buffer chamber is communicated with the shunting type molecular pump, the buffer chamber is communicated with a first vacuum gauge, and a second pipeline communicated with the first pipeline is arranged on the buffer chamber;
a surge chamber valve disposed on the second conduit, the surge chamber valve being always maintained in an open state.
3. The vacuum system for a scanning electron microscope according to claim 2, characterized in that a third pipeline is provided between the main extraction opening and the electron gun, a second vacuum gauge is provided on the third pipeline, the detection accuracy of the second vacuum gauge is higher than that of the first vacuum gauge, and the second vacuum gauge is in communication connection or electric connection with the first vacuum gauge and is turned on or off according to the detection result of the first vacuum gauge.
4. The vacuum system for scanning electron microscopes according to claim 3, wherein a fourth pipeline communicated with the first pipeline is disposed on the third pipeline, and a second vacuum isolation valve is disposed on the fourth pipeline.
5. The vacuum system for scanning electron microscopes according to claim 1, wherein a fifth pipeline is arranged between the sample chamber and the air source control part, and a third vacuum isolation valve is arranged on the fifth pipeline.
6. The vacuum system for scanning electron microscopes according to claim 1, wherein the sample chamber is communicated with a fast air inlet valve, an air outlet valve and a third vacuum gauge, and the third vacuum gauge is in communication connection or electrical connection with the air source control component to control the operation of the air source control component.
7. The vacuum system for scanning electron microscopes according to claim 1, wherein a sixth pipeline is disposed between the shunt suction opening and the objective lens air gap interlayer, and a fourth vacuum isolation valve is disposed on the sixth pipeline.
8. A method of controlling a vacuum system for a scanning electron microscope, comprising the vacuum system for a scanning electron microscope according to claim 1, the method comprising:
the first vacuum isolating valve is opened and is closed after the mechanical pump pumps the sample chamber to a first preset air pressure;
the shunting type molecular pump pumps and maintains vacuum in the objective lens air gap interlayer and the electron gun;
and the gas source control piece is opened to supply gas into the sample chamber.
9. The method of claim 8, further comprising a buffer chamber communicating the split molecular pump and the mechanical pump; the method further comprises the following steps:
when the air pressure in the sample chamber needs to be reduced, the conduction of the buffer chamber and the mechanical pump is cut off, and the first vacuum isolation valve is opened;
after the mechanical pump pumps the sample chamber to a second preset air pressure, closing the first vacuum isolation valve;
and recovering the conduction of the buffer chamber and the mechanical pump, and pumping and maintaining the vacuum in the objective lens air gap interlayer and the electron gun by the shunt type molecular pump.
10. The method of controlling a vacuum system according to claim 9, further comprising:
detecting the vacuum degree in the buffer chamber in real time;
and if the vacuum degree in the buffer chamber reaches a set value, starting to detect the vacuum degree in the electron gun.
11. The method of claim 8, wherein a main pumping port of the split-flow molecular pump is communicated with a pumping pipeline of the mechanical pump, and the first vacuum isolation valve is opened and closed after the mechanical pump pumps the sample chamber to a preset air pressure:
when the first vacuum isolating valve is opened, the main air suction port is communicated with an air suction pipeline of the mechanical pump;
and when the first vacuum isolation valve is closed, the main extraction opening is cut off from the air extraction pipeline of the mechanical pump.
12. The method of claim 8, wherein the step of the split molecular pump drawing and maintaining a vacuum within the objective airgap interlayer and the electron gun further comprises:
and detecting the vacuum degree in the sample chamber in real time, and controlling the air source control part to work according to the detection result.
13. The method of claim 8, wherein the gas supply control and the sample chamber are normally kept disconnected, and wherein the step of opening the gas supply control and supplying gas to the sample chamber further comprises: and communicating the gas source control part with the sample chamber.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210772944.5A CN115148567A (en) | 2022-06-30 | 2022-06-30 | Vacuum system of scanning electron microscope and control method thereof |
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| CN202210772944.5A CN115148567A (en) | 2022-06-30 | 2022-06-30 | Vacuum system of scanning electron microscope and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115460760A (en) * | 2022-11-09 | 2022-12-09 | 合肥中科离子医学技术装备有限公司 | Vacuum control system of cyclotron |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115460760A (en) * | 2022-11-09 | 2022-12-09 | 合肥中科离子医学技术装备有限公司 | Vacuum control system of cyclotron |
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