Ion detection device and mass spectrometer

Abstract

The utility model provides an ion detection device and a mass spectrometer, the ion detection device comprises a focusing electrode connected at the outlet of a mass analyzer, the end part of the focusing electrode far away from the mass analyzer is provided with a first outlet for an ion beam to pass through, the side wall of the focusing electrode is provided with a second outlet, and the outer side of the second outlet is provided with a micro-channel plate; and the second amplifier is used for performing electric signal amplification on the deflected ion beam passing through the second outlet. According to the utility model, the voltage applied to the first end face of the micro-channel plate is used for deflecting ions, so that an additional deflection electrode arranged in a traditional scheme is avoided, the space is saved, an additional power supply is not needed, the whole module is more miniaturized, meanwhile, a grid deflection electrode needed in a traditional dual detector does not need to be added, and the detection efficiency is improved. The influence of the grid mesh on the ion permeability is reduced, the detection sensitivity of the system is improved, and the structure of the detector can be simplified so as to reduce the design difficulty and the material cost.

Description

Technical Field

[0001] The utility model relates to the technical field of mass spectrometers, in particular to an ion detection device and a mass spectrometer. Background Art

[0002] A mass spectrometer, also known as a mass spectrometer, is an instrument that ionizes chemical substances and separates and detects them based on their mass-to-charge ratio. A mass spectrometer is composed of an ion source, a mass analyzer, and an ion detector. The ion source ionizes sample molecules under vacuum conditions. Ions of different mass-to-charge ratios (m / z) acquire the same average kinetic energy under the action of an accelerating electric field and enter the mass analyzer. The mass analyzer uses an electric or magnetic field to separate ions of different mass-to-charge ratios entering simultaneously in space or time. The separated ions then enter the ion detector, where they are converted into electrical signals and processed by a computer to produce a mass spectrum.

[0003] Common ion detectors include Faraday cups, electron multipliers, microchannel plates, and photomultiplier tubes. To expand the detection limits of mass spectrometers, particularly in semiconductor process monitoring applications where large variations in vacuum levels are detected, mass spectrometers are typically equipped with two ion detectors with different gains. These detectors are switched by changing the direction of ions after exiting the mass analyzer.

[0004] A common method for changing the direction of ion flight is to set up additional deflection electrodes near the ion exit. When the ion signal is strong, the deflection electrodes do not work, and the ion beam reaches the opposite, non-gain Faraday cup detector in a straight line. When the ion signal is weak, the deflection electrodes work, and the ion beam is deflected by the electric field force, reaching the high-gain ion detector located on the side to amplify the signal. The deflection electrodes require an additional power supply to control, and the deflection electrodes of the ion detector near the side need to use grid-shaped electrodes to allow the ion beam to pass through. The two additional deflection electrodes not only increase the difficulty of the detector's manufacturing process and its size, but also cause some ions to be interfered with by the grid wires as the ion beam passes through the grid electrode to reach the detector, reducing the ion permeability and thus the detection sensitivity of the system. Utility Model Content

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a solution for achieving dual-detector switching without the need for additional deflection electrodes, which has not only a simple structure and a compact space, but also a high ion permeability.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides an ion detection device, comprising a focusing electrode, wherein the focusing electrode is cylindrical and one end of the focusing electrode is provided with a first outlet for the ion beam to pass through;

[0007] A second outlet is provided on the side wall of the focusing electrode, and a microchannel plate is placed outside the second outlet. The microchannel plate includes a first end face and a second end face opposite to each other, both of which are conductive surfaces. The first end face is located between the second end face and the focusing electrode. The electric field formed between the focusing electrode and the first end face is used to deflect the ion beam through the second outlet to reach the microchannel plate. The electric field formed between the first end face and the second end face is used to generate secondary electrons and multiply them, thereby enhancing the signal.

[0008] Optionally, the first outlet and the second outlet are circular or square in shape.

[0009] Optionally, a first ion detector is also included, which is L-shaped and includes a side plate and a bottom plate vertically connected, the bottom plate is opposite to the first outlet, and the side plate is located on the side of the microchannel plate away from the focusing electrode. The side plate and the bottom plate are both equipped with detection units for detecting the electrical signal generated by the ion beam.

[0010] Optionally, the detection unit includes a Faraday cup detector.

[0011] Optionally, both the first end surface and the second end surface comprise a metal layer. Optionally, an insulating layer is provided between the side wall of the focusing electrode close to the microchannel plate and the microchannel plate.

[0012] Optionally, the insulating layer is a ceramic layer or a polytetrafluoroethylene layer.

[0013] The utility model also provides a mass spectrometer, comprising the ion detection device.

[0014] Optionally, it also includes:

[0015] Ion source, used to ionize sample molecules under high vacuum conditions;

[0016] The mass analyzer is used to separate ions with different mass-to-charge ratios generated in the ion source in space or time. The separated ions enter the ion detection device, and the other end of the focusing electrode is connected to the mass analyzer.

[0017] Optionally, the mass analyzer includes one of a quadrupole mass analyzer, a time-of-flight mass analyzer, an ion trap mass analyzer, and a magnetic field mass analyzer.

[0018] As described above, the present invention provides an ion detection device and a mass spectrometer. The ion detection device innovatively uses the voltage applied to the first end face of the microchannel plate to deflect ions, thereby avoiding the additional deflection electrodes provided in traditional solutions. This saves space and eliminates the need for an additional power supply. This not only makes the entire module more compact and saves design and material costs, but also eliminates the need for the grid deflection electrodes required in traditional dual detectors, reducing the effect of the grid on ion permeability, improving the detection sensitivity of the system, and simplifying the detector structure to reduce design difficulty and material costs. Compared with existing solutions that use additional electrodes to change the flight direction of ions, the present invention uses the electric field generated by a high-gain detector to deflect ions, resulting in a simple structure and reducing the design and processing of additional ion deflection electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram showing the ion beam entering the first ion detector along a straight line in the ion detection device of the present invention.

[0020] Figure 2 It shows a schematic diagram of the ion beam deflecting into the microchannel plate in the ion detection device of the present invention.

[0021] Figure 3 The figure shows the flight trajectory of the ion with m / z=40 under the detection conditions of the first ion detector used in the present invention.

[0022] Figure 4 The display shows the flight trajectory of the ion with m / z=40 under the detection conditions of the present invention using a microchannel plate.

[0023] Component number description

[0024] 1 Focusing electrode

[0025] 2. First ion detector

[0026] 3 Microchannel Plate

[0027] 4 Mass Analyzer

[0028] 5 Insulation layer

[0029] 31 First end face

[0030] 32 Second end face DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different perspectives and applications without departing from the spirit of the present invention.

[0032] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0033] Example 1

[0034] like Figures 1 to 2 As shown, this embodiment provides an ion detection device, including:

[0035] A focusing electrode 1, which is cylindrical and connected to the outlet of the mass analyzer 4 along its length. The end of the focusing electrode 1 away from the mass analyzer 4 is provided with a first outlet for the ion beam to pass through;

[0036] A second outlet is provided on the side wall of the focusing electrode 1 , and a microchannel plate 3 is placed outside the second outlet for amplifying the electrical signal of the ion beam passing through the second outlet after deflection; the shapes of the first outlet and the second outlet can be circular or square.

[0037] The first ion detector 2 is L-shaped and includes a vertically connected side plate and a bottom plate. The bottom plate faces the first outlet, and the side plate is located on the side of the microchannel plate 3 away from the focusing electrode 1. The side plate and the bottom plate are both equipped with a detection unit for receiving electrical signals. The detection unit can be a Faraday cup detector.

[0038] Furthermore, the microchannel plate (MCP) 3 is a vacuum electronic device with electron multiplication capabilities. It is primarily composed of millions to tens of millions of ultra-thin conductive glass capillaries, each capillary channel lined with a specific secondary electron emission material. When ions strike the inner wall of the microchannel, multiple secondary electrons are generated. These electrons are then accelerated by the electric field applied to the two end surfaces of the microchannel plate 3 and strike the next inner wall again, generating further secondary electrons. This process is repeated multiple times along the channel, ultimately releasing a large number of electrons from the output end.

[0039] The microchannel plate 3 includes a first end face 31 and a second end face 32 opposite to each other. The first end face 31 is located between the second end face 32 and the focusing electrode 1. Both end faces are plated with a metal layer to form an input electrode and an output electrode. When a voltage is applied to the two end faces, a uniform electric field is established along the axial direction in the channel to achieve electron multiplication.

[0040] Furthermore, when the ion beam signal is strong, the ion beam passes directly through the first outlet, and the voltage applied to the first end surface 31 and the second end surface 32 is 0 to -100 V, that is, the microchannel plate 3 is not working, and the ions emitted from the mass analyzer 4 are focused by the focusing electrode 1 and then collected by the detection unit of the bottom plate of the first ion detector 2;

[0041] When the ion beam signal is weak, the ion beam is deflected and passes through the second exit. The voltages applied to the focusing electrode 1 and the second end face 32 are the same, while the voltage applied to the first end face 31 is higher. The electric field formed between the focusing electrode 1 and the first end face 31 is used to deflect the ion beam through the second exit to the microchannel plate 3. The electric field formed between the first end face 31 and the second end face 32 is used to multiply the electrons, thereby enhancing the signal. Electrons emitted from the microchannel plate 3 further reach the side plate of the first ion detector 2 and are captured by the detection unit of the side plate for detection. For example, the voltage applied to the focusing electrode 1 is -20V, the voltage applied to the first end face 31 is -600V to -1300V, and the voltage applied to the second end face 32 is -20V. There is a voltage difference of more than 500V between the first end face 31 and the second end face 32. It should be understood that the side wall area of the focusing electrode 1 opposite to the second outlet can be regarded as an electrode sheet, that is, the side wall area facing the first end face 31 through the second outlet can be regarded as an electrode sheet, thereby matching the first end face 31 to form an electric field.

[0042] Furthermore, an insulating layer 5 is provided between the side wall of the focusing electrode 1 close to the microchannel plate 3 and the microchannel plate 3. The insulating layer 5 has an opening adapted to the second outlet to allow the ion beam to pass through. The insulating layer 5 is a ceramic layer, polytetrafluoroethylene or polyetheretherketone layer.

[0043] Specifically, Figures 3 and 4 In a simulation experiment conducted for this embodiment using Simion software, a ground electrode was added in front of the focusing electrode 1 to simulate the electric field environment during ion incidence.

[0044] Figure 3 This is a simulated flight trajectory of ions in the device when the voltage of the focusing electrode 1 is -120V and the voltage of the microchannel plate 3 is -60V. The ions with initial spatial divergence can be converged under the action of the focusing electrode 1 and reach the bottom plate of the first detector 2.

[0045] Figure 4This is the simulated flight trajectory of ions in the device when the voltage of focusing electrode 1 is -20V and the voltage of microchannel plate 3 is -800V. The focused ions are deflected by the electric field between V0 and V1 and reach microchannel plate 3.

[0046] Compared with the existing solution of using additional electrodes to change the flight direction of ions, this embodiment uses the electric field generated by a high-gain detector to deflect ions, has a simple structure, and reduces the design and processing of additional ion deflection electrodes.

[0047] Example 2

[0048] Based on the ion detection device in the first embodiment, this embodiment provides a mass spectrometer, which includes the ion detection device in the first embodiment, and further includes:

[0049] Ion source, used to ionize sample molecules under high vacuum conditions;

[0050] The mass analyzer is used to separate ions of different mass-to-charge ratios generated in the ion source in space or time, and the separated ions enter the ion detection device.

[0051] Furthermore, the mass analyzer may be a quadrupole mass analyzer, a time-of-flight mass analyzer, an ion trap mass analyzer, a magnetic field mass analyzer, or the like.

[0052] In summary, the utility model provides an ion detection device and a mass spectrometer, the ion detection device includes a focusing electrode connected to the outlet of a mass analyzer, a first outlet is provided at the end of the focusing electrode away from the mass analyzer for the ion beam to pass through, a second outlet is provided on the side wall of the focusing electrode, a microchannel plate is placed on the outside of the second outlet, for amplifying the electrical signal of the ion beam passing through the second outlet after deflection; the first ion detector is L-shaped, including a side plate and a bottom plate connected vertically, the bottom plate is opposite to the first outlet, the side plate is located on the side of the microchannel plate away from the focusing electrode, and both the side plate and the bottom plate are equipped with detection units. When the ion beam signal is strong, the ion beam passes directly through the first outlet and is collected by the detection unit on the bottom plate of the first ion detector; when the ion beam signal is weak, the ion beam passes through the second outlet after deflection, and the electric field formed between the focusing electrode and the first end face is used to deflect the ion beam through the second outlet to reach the microchannel plate. The electric field formed between the first end face and the second end face is used to generate electron multiplication, thereby enhancing the signal. The electrons emitted from the microchannel plate further reach the side plate of the first ion detector and are captured by the detection unit on the side plate to achieve detection.

[0053] This utility model innovatively uses the voltage applied to the first end face of the microchannel plate to deflect ions, thereby avoiding the need for additional deflection electrodes in conventional solutions. This saves space and eliminates the need for an additional power supply, making the entire module more compact and saving design and material costs. It also eliminates the need for the additional grid deflection electrodes required in conventional dual detectors, reducing the grid's impact on ion permeability and improving the system's detection sensitivity. It also simplifies the detector structure, lowering design complexity and material costs. Compared to existing solutions that use additional electrodes to change the direction of ion flight, this utility model uses the electric field generated by a high-gain detector to deflect ions, resulting in a simpler structure and eliminating the need for the design and processing of additional ion deflection electrodes.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed in the present invention are intended to be covered by the claims of the present invention.

Claims

1. An ion detection device, characterized in that: The focusing electrode comprises a focusing electrode, wherein the focusing electrode is cylindrical and one end of the focusing electrode is provided with a first outlet for the ion beam to pass through; A second outlet is provided on the side wall of the focusing electrode, and a microchannel plate is placed outside the second outlet. The microchannel plate includes a first end face and a second end face opposite to each other, both of which are conductive surfaces. The first end face is located between the second end face and the focusing electrode. The electric field formed between the focusing electrode and the first end face is used to deflect the ion beam through the second outlet to reach the microchannel plate. The electric field formed between the first end face and the second end face is used to generate electron multiplication, thereby enhancing the signal.

2. The ion detection device according to claim 1, characterized in that: The shapes of the first outlet and the second outlet are circular or square.

3. The ion detection device according to claim 1, wherein: It also includes a first ion detector, which is L-shaped and includes a side plate and a bottom plate connected vertically. The bottom plate is opposite to the first outlet, and the side plate is located on the side of the microchannel plate away from the focusing electrode. The side plate and the bottom plate are both equipped with detection units for detecting the electrical signal generated by the ion beam.

4. The ion detection device according to claim 3, characterized in that: The detection unit includes a Faraday cup detector.

5. The ion detection device according to claim 1, wherein: The first end surface and the second end surface both include a metal layer.

6. The ion detection device according to claim 1, characterized in that: An insulating layer is provided between the side wall of the focusing electrode close to the microchannel plate and the microchannel plate.

7. The ion detection device according to claim 6, characterized in that: The insulating layer is a ceramic layer, a polytetrafluoroethylene layer or a polyetheretherketone layer.

8. A mass spectrometer, characterized in that: The invention comprises an ion detection device as described in any one of claims 1 to 7.

9. The mass spectrometer according to claim 8, characterized in that Also includes: Ion source, used to ionize sample molecules under high vacuum conditions; The mass analyzer is used to separate ions with different mass-to-charge ratios generated in the ion source in space or time. The separated ions enter the ion detection device, and the other end of the focusing electrode is connected to the mass analyzer.

10. The mass spectrometer according to claim 9, characterized in that: The mass analyzer includes one of a quadrupole mass analyzer, a time-of-flight mass analyzer, an ion trap mass analyzer, and a magnetic field mass analyzer.

Images