Schottky electron source module parameter determination device and method

Abstract

The invention discloses a Schottky electron source module parameter determination device and method, and belongs to the field of scanning electron microscopes, a power-on device applies a preset current to a Schottky electron source module to heat a filament, and applies a preset voltage to generate a strong electric field on a needle tip accessory to generate electrons, an electron beam hits a fluorescent screen to emit light, and the fluorescent screen emits light. Whether the electron beam shape on the fluorescent screen and the ground current size coarse identification parameters are appropriate or not is observed through the camera, if yes, the vacuum valve is opened, the Schottky electron source module is conveyed to the second vacuum cavity through the conveying structure, and the scanning electron microscope directly observes the real appearance of the surface of the needle point in the second vacuum cavity; therefore, whether current and voltage parameters are appropriate or not is accurately judged, the Schottky electron source module can be preliminarily determined firstly, then the actual appearance of the surface of a needle tip of the Schottky electron source module is directly observed through a scanning electron microscope, and continuous evolution of the appearance of crystal lattices on the surface of a lamp filament is further observed. And the optimal parameters corresponding to the Schottky electron source module can be accurately obtained.

Description

Technical Field

[0001] The present invention relates to the field of scanning electron microscopes, and in particular to a device and method for determining parameters of a Schottky electron source module. Background Art

[0002] The resolution of high-resolution field emission scanning electron microscopes is primarily guaranteed by low-aberration objective lens design and a high-brightness, low-energy-dispersion electron source. The former provides the system with small spherical and chromatic aberration coefficients, reducing the spread of the focused electron beam caused by spherical and chromatic aberrations, and is designed with electron optics software. The latter provides the system with sufficient detection beam current and low energy dispersion.

[0003] One type of electron source for a scanning electron microscope is a Schottky thermal field emission electron source. This requires strict matching of the filament temperature and the electric field strength on the tip surface to achieve a steady-state equilibrium, and the surface must maintain a specific lattice morphology. In existing technologies, the filament temperature is controlled by current, and the electric field strength is controlled by voltage. A preset current and voltage are applied to the tip, and the beam current and the shape of the electron beam spot on the fluorescent screen are observed to reflect the filament surface morphology, thereby determining the corresponding current and voltage parameters. However, the shape of the electron beam spot on the fluorescent screen cannot capture the slightest changes in the shape of the tip, resulting in the determined parameters not necessarily being strictly matched, causing the Schottky electron source to gradually fail after long-term operation. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a Schottky electron source module parameter determination device that can accurately obtain the optimal parameters corresponding to the Schottky electron source module.

[0005] In order to overcome the deficiencies of the prior art, a second object of the present invention is to provide a method for determining parameters of a Schottky electron source module that can accurately obtain the optimal parameters corresponding to the Schottky electron source module.

[0006] One of the purposes of the present invention is achieved by the following technical solution:

[0007] A Schottky electron source module parameter determination device includes a first vacuum chamber, a power-on device, a Schottky electron source module, and an optical characterization module, wherein the optical characterization module includes a fluorescent screen and a camera, wherein the fluorescent screen is arranged on the side wall of the first vacuum chamber, and the camera faces the fluorescent screen. The power-on device is installed in the first vacuum chamber, and the Schottky electron source module parameter determination device also includes a transmission structure, a vacuum valve, a second vacuum chamber, and a scanning electron microscope. The vacuum degree of the second vacuum chamber is greater than the vacuum degree of the first vacuum chamber. The vacuum valve is installed between the first vacuum chamber and the second vacuum chamber. The power-on device is installed in the first vacuum chamber. The device applies a preset current and a preset voltage to the Schottky electron source module, and the Schottky electron source module generates electrons, and the electron beam hits the fluorescent screen to emit light. The camera observes the shape of the electron beam on the fluorescent screen and the magnitude of the current to the ground to roughly identify whether the current and voltage parameters are appropriate. When the current and voltage parameters are appropriate, the vacuum valve opens, and the transmission structure transports the Schottky electron source module to the second vacuum chamber. The scanning electron microscope directly observes the true morphology of the needle tip surface of the Schottky electron source module in the second vacuum chamber, thereby accurately judging whether the current and voltage parameters are appropriate.

[0008] Furthermore, the power-on device includes a power supply, a base, and a vacuum cavity connector connected to the base, the base is used to install the Schottky electron source module, and the vacuum cavity connector is used to apply a preset current and a preset voltage.

[0009] Furthermore, the Schottky electron source module parameter determination device also includes a connecting cavity, which is located between the first vacuum cavity and the second vacuum cavity, the connecting cavity connects the first vacuum cavity and the second vacuum cavity, and the vacuum valve is installed in the connecting cavity.

[0010] Furthermore, the gas pressure of the first vacuum chamber is 1e-5 to 1e-7 mbar.

[0011] Furthermore, the gas pressure of the second vacuum chamber is less than 5e-9 mbar.

[0012] Furthermore, the transmission structure includes a transmission rod, a first magnet and a second magnet, the transmission rod is fixedly connected to the first magnet, the transmission rod is at least partially located in the first vacuum chamber, the transmission rod is fixedly connected to the Schottky electron source module, and the second magnet moves outside the first vacuum chamber to drive the second magnet to move so that the transmission rod drives the Schottky electron source module to move to the second vacuum chamber.

[0013] Furthermore, the transmission structure also includes a fixed rod, which is fixed to the outside of the first vacuum chamber. The inside of the fixed rod is a hollow structure and is vacuumed. The transmission rod is slidably installed inside the fixed rod, and the second magnet is slidably installed outside the fixed rod.

[0014] Furthermore, the first vacuum chamber and the second vacuum chamber are located on the same straight line.

[0015] Furthermore, the axis of the scanning electron microscope is perpendicular to the straight line where the first vacuum chamber and the second vacuum chamber are located.

[0016] The second object of the present invention is achieved by adopting the following technical solution:

[0017] A method for determining parameters of a Schottky electron source module based on any of the above-mentioned Schottky electron source module parameter determination devices comprises the following steps:

[0018] Installing a Schottky electron source module in the first vacuum chamber, and applying a preset current and a preset voltage to the Schottky electron source module through a power-on device;

[0019] The Schottky electron source module generates electrons, and the electron beam hits the fluorescent screen to emit light. The shape of the electron beam on the fluorescent screen and the current to ground are observed by a camera to roughly identify whether the current and voltage parameters are appropriate;

[0020] When the current and voltage parameters are initially appropriate, the vacuum valve is opened, and the transport structure transports the Schottky electron source module to the second vacuum chamber;

[0021] The scanning electron microscope directly observes the actual morphology evolution process of the tip surface of the Schottky electron source module in the second vacuum chamber, thereby accurately judging whether the current and voltage parameters are appropriate.

[0022] Furthermore, the axis of the scanning electron microscope is perpendicular to the straight line where the first vacuum chamber and the second vacuum chamber are located.

[0023] Compared with the prior art, the Schottky electron source module parameter determination device of the present invention includes a first vacuum chamber, a power-on device, a Schottky electron source module and an optical characterization module, the optical characterization module includes a fluorescent screen and a camera, the fluorescent screen is arranged on the side wall of the first vacuum chamber, the camera is directly opposite to the fluorescent screen, the power-on device is installed in the first vacuum chamber, the Schottky electron source module parameter determination device also includes a transmission structure, a vacuum valve, a second vacuum chamber and a scanning electron microscope, the vacuum degree of the second vacuum chamber is greater than the vacuum degree of the first vacuum chamber, the vacuum valve is installed between the first vacuum chamber and the second vacuum chamber, the power-on device applies a preset current and voltage to the Schottky electron source module, the Schottky electron source module generates electrons, the electron beam hits the fluorescent screen to emit light, and the fluorescent light is observed by the camera The shape of the electron beam on the light screen roughly identifies whether the current and voltage parameters are appropriate. When the current and voltage parameters are appropriate, the vacuum valve opens, and the transmission structure transports the Schottky electron source module to the second vacuum chamber. The scanning electron microscope directly observes the evolution process of the real morphology of the tip surface of the Schottky electron source module in the second vacuum chamber, thereby accurately judging whether the current and voltage parameters are appropriate. Through the above design, the Schottky electron source module can be preliminarily determined first. When it is preliminarily determined that the parameters are appropriate, the Schottky electron source module is transported to the second vacuum chamber, and the real morphology of the tip surface of the Schottky electron source module is directly observed by the scanning electron microscope, thereby further observing the continuous evolution of the lattice morphology of the filament surface, thereby accurately obtaining the optimal parameters corresponding to the Schottky electron source module. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a rough identification of a device for determining parameters of a Schottky electron source module according to the present invention;

[0025] Figure 2 for Figure 1 Schematic diagram of accurate identification of Schottky electron source module parameter determination device;

[0026] Figure 3 for Figure 2 The tip surface topography during accurate identification by the Schottky electron source module parameter determination device;

[0027] Figure 4 This is a flow chart of the method for determining parameters of a Schottky electron source module of the present invention.

[0028] In the figure: 10, first vacuum chamber; 20, power-on device; 21, base; 22, vacuum through-cavity connector; 30, Schottky electron source module; 40, optical characterization module; 41, fluorescent screen; 42, camera; 50, transmission structure; 51, fixing rod; 52, transmission rod; 53, first magnet; 54, second magnet; 60, vacuum valve; 70, connecting chamber; 80, second vacuum chamber; 90, scanning electron microscope. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] See also Figure 1 as well as Figure 2 The Schottky electron source module parameter determination device of the present invention includes a first vacuum chamber 10, a power-on device 20, a Schottky electron source module 30, an optical characterization module 40, a transmission structure 50, a vacuum valve 60, a connecting chamber 70, a second vacuum chamber 80 and a scanning electron microscope 90.

[0032] The first vacuum chamber 10 is used to apply a preset current and voltage to induce the Schottky electron source module 30 to generate electrons and enable the optical characterization module 40 to perform preliminary identification. The pressure in the first vacuum chamber 10 is between 1e-5 and 1e-7 mbar. The first vacuum chamber 10 is used to house the power-up device 20, the Schottky electron source module 30, the optical characterization module 40, and the transfer structure 50.

[0033] The power-on device 20 includes a base 21 and a vacuum cavity connector 22 connected to the base 21 . The base 21 is used to mount the Schottky electron source die 30 . The connector 22 is used to apply a preset current and voltage to the Schottky electron source die 30 .

[0034] The Schottky electron source module 30 is a key component of a high-resolution field emission scanning electron microscope. It requires a strict match between the filament temperature and the electric field strength at the tip surface to achieve a steady-state equilibrium, maintaining a specific lattice morphology on the surface. The filament temperature is controlled by controlling the current, while the electric field strength at the tip surface is controlled by controlling the voltage. As the filament temperature and extraction voltage are applied to the Schottky electron source module 30, the lattice morphology on the filament surface continuously evolves.

[0035] The optical characterization module 40 includes a fluorescent screen 41 and a camera 42. The fluorescent screen 41 is installed on the side wall of the first vacuum chamber 10, and the camera 42 is facing the fluorescent screen 41. In the needle tip preparation mode, after applying the filament temperature and the extraction electrode voltage, the electron beam hits the fluorescent screen 41 to emit light, and then the shape of the electron beam can be seen through the camera 42 (CCD). By combining the beam current and beam spot shape on the fluorescent screen 41, it can be roughly determined whether the applied parameters are appropriate. Because the lattice morphology of the filament surface will continuously evolve after the Schottky electron source module 30 applies the filament temperature and the extraction electrode voltage. The fluorescent screen 41 and the camera 42 cannot capture this slight change in the shape of the needle tip, so a scanning electron microscope 90 is required for further observation to accurately determine whether the current and voltage parameters are appropriate.

[0036] The transmission structure 50 is used to transmit the Schottky electron source module 30 to the second vacuum chamber 80 in a vacuum environment when the optical characterization module 40 determines that the current and voltage parameters are initially suitable, so that the scanning electron microscope 90 can directly observe the surface morphology evolution process and accurately correlate the microscopic morphology and emission characteristics. Specifically, the transmission structure 50 includes a fixed rod 51, a transmission rod 52, a first magnet 53, and a second magnet 54. The fixed rod 51 is fixed to the first vacuum chamber 10. The interior of the fixed rod 51 is a hollow structure, and the interior of the fixed rod 51 is connected to the first vacuum chamber 10. The transmission rod 52 is slidably mounted inside the fixed rod 51. The end of the transmission rod 52 extends from the interior of the fixed rod 51 and is fixedly connected to the Schottky electron source module 30. The first magnet 53 is fixed to the transmission rod 52, and the second magnet 54 is slidably mounted outside the fixed rod 51. The second magnet 54 and the first magnet 53 are mutually attracted to each other with the fixed rod 51 between them. When the second magnet 54 slides outside the fixing rod 51 , it drives the first magnet 53 , the transmission rod 52 and the Schottky electron source module 30 to move, thereby moving the Schottky electron source module 30 from the first vacuum chamber 10 to the second vacuum chamber 80 .

[0037] The vacuum valve 60 is installed between the first vacuum chamber 10 and the second vacuum chamber 80 to maintain the vacuum state of the second vacuum chamber 80 .

[0038] The communication chamber 70 is disposed between the first vacuum chamber 10 and the second vacuum chamber 80 . The first vacuum chamber 10 , the communication chamber 70 , and the second vacuum chamber 80 are located on the same straight line. The vacuum valve 60 is disposed on the communication chamber 70 .

[0039] The air pressure of the second vacuum chamber 80 is less than 5e-9 mbar. The second vacuum chamber 80 is used to provide a vacuum degree when the scanning electron microscope 90 is working.

[0040] The scanning electron microscope 90 is used to directly observe the tip surface morphology of the Schottky electron source module 30 and accurately correlate the microscopic morphology and emission characteristics. Since the filament surface lattice morphology of the Schottky electron source module 30 will continuously evolve after the filament temperature and extraction electrode voltage are applied, such as Figure 3 As shown, the scanning electron microscope 90 can continuously observe the evolution of the lattice morphology on the surface of the filament, thereby further accurately judging whether the current and voltage parameters are appropriate.

[0041] Please continue reading Figure 4 The present application also discloses a method for determining parameters of a Schottky electron source module based on the above-mentioned Schottky electron source module parameter determination device, comprising the following steps:

[0042] The Schottky electron source module 30 is installed in the first vacuum chamber 10, and a preset current and voltage are applied to the Schottky electron source module 30 through the power-on device 20;

[0043] The Schottky electron source module 30 generates electrons, and the electron beam hits the fluorescent screen 41 to emit light. The shape of the electron beam on the fluorescent screen 41 is observed by the camera 42 to roughly identify whether the current and voltage parameters are appropriate.

[0044] When the current and voltage parameters are initially appropriate, the vacuum valve 60 is opened, and the transport structure 50 transports the Schottky electron source module 30 to the second vacuum chamber 80 ;

[0045] The scanning electron microscope 90 directly observes the true morphology of the tip surface of the Schottky electron source module 30 in the second vacuum chamber 80 , thereby accurately judging whether the current and voltage parameters are appropriate.

[0046] Compared with the prior art, the power-on device 20 of the Schottky electron source module parameter determination device of the present invention applies a preset current and voltage to the Schottky electron source module 30, and the Schottky electron source module 30 generates electrons, and the electron beam hits the fluorescent screen 41 to emit light. The shape of the electron beam on the fluorescent screen 41 is observed by the camera 42 to roughly identify whether the current and voltage parameters are appropriate. When the current and voltage parameters are appropriate, the vacuum valve 60 is opened, and the conveying structure 50 conveys the Schottky electron source module 30 to the second vacuum chamber 80, and the scanning electron microscope 90 directly observes the second vacuum chamber. The actual surface morphology of the tip of the Schottky electron source module 30 in the cavity 80 is observed, so as to accurately judge whether the current and voltage parameters are appropriate. Through the above design, the Schottky electron source module 30 can be preliminarily determined first. When the parameters are preliminarily determined to be appropriate, the Schottky electron source module 30 is transported to the second vacuum cavity 80 and the actual surface morphology of the tip of the Schottky electron source module 30 is directly observed by the scanning electron microscope 90, so as to further observe the continuous evolution of the lattice morphology of the filament surface, so as to accurately obtain the optimal parameters corresponding to the Schottky electron source module 30.

[0047] The above embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patented invention. It should be noted that those skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention. These variations and improvements are equivalent modifications and improvements to the above embodiments based on the essential technology of the present invention and fall within the scope of protection of the present invention.

Claims

1. A device for determining parameters of a Schottky electron source module, comprising a first vacuum chamber, a power-up device, a Schottky electron source module, and an optical characterization module, wherein the optical characterization module comprises a fluorescent screen and a camera, the fluorescent screen being disposed on a sidewall of the first vacuum chamber, the camera facing the fluorescent screen, and the power-up device being mounted in the first vacuum chamber, characterized in that: The Schottky electron source module parameter determination device also includes a transmission structure, a vacuum valve, a second vacuum chamber and a scanning electron microscope. The vacuum degree of the second vacuum chamber is greater than the vacuum degree of the first vacuum chamber. The vacuum valve is installed between the first vacuum chamber and the second vacuum chamber. The power-on device applies a preset current and a preset voltage to the Schottky electron source module. The Schottky electron source module generates electrons, and the electron beam hits the fluorescent screen to emit light. The camera observes the shape of the electron beam on the fluorescent screen and the size of the ground current to roughly identify whether the current and voltage parameters are appropriate. When the current and voltage parameters are appropriate, the vacuum valve opens, and the transmission structure transports the Schottky electron source module to the second vacuum chamber. The scanning electron microscope directly observes the true morphology of the needle tip surface of the Schottky electron source module in the second vacuum chamber, thereby accurately judging whether the current and voltage parameters are appropriate.

2. The device for determining parameters of a Schottky electron source module according to claim 1, wherein: The power-on device includes a power supply, a base, and a vacuum cavity connector connected to the base. The base is used to install the Schottky electron source module, and the vacuum cavity connector is used to apply a preset current and a preset voltage.

3. The device for determining parameters of a Schottky electron source module according to claim 1, wherein: The Schottky electron source module parameter determination device further includes a connecting cavity, which is located between the first vacuum cavity and the second vacuum cavity, the connecting cavity connecting the first vacuum cavity and the second vacuum cavity, and the vacuum valve is installed in the connecting cavity.

4. The device for determining parameters of a Schottky electron source module according to claim 3, wherein: The gas pressure of the first vacuum chamber is 1e-5 to 1e-7 mbar.

5. The device for determining parameters of a Schottky electron source module according to claim 3, wherein: The gas pressure of the second vacuum chamber is less than 5e-9 mbar.

6. The device for determining parameters of a Schottky electron source module according to claim 1, wherein: The transmission structure includes a transmission rod, a first magnet and a second magnet. The transmission rod is fixedly connected to the first magnet. The transmission rod is at least partially located in the first vacuum chamber. The transmission rod is fixedly connected to the Schottky electron source module. The second magnet moves outside the first vacuum chamber, thereby driving the second magnet to move, so that the transmission rod drives the Schottky electron source module to move to the second vacuum chamber.

7. The device for determining parameters of a Schottky electron source module according to claim 6, wherein: The transmission structure also includes a fixed rod, which is fixed to the outside of the first vacuum chamber. The inside of the fixed rod is a hollow structure and is vacuumed. The transmission rod is slidably installed inside the fixed rod, and the second magnet is slidably installed outside the fixed rod.

8. The device for determining parameters of a Schottky electron source module according to claim 6, wherein: The first vacuum chamber and the second vacuum chamber are located on the same straight line.

9. The device for determining parameters of a Schottky electron source module according to claim 8, wherein: The axis of the scanning electron microscope is perpendicular to the straight line where the first vacuum chamber and the second vacuum chamber are located.

10. A method for determining parameters of a Schottky electron source module based on the device for determining parameters of a Schottky electron source module according to any one of claims 1 to 9, characterized in that: The following steps are involved: Installing a Schottky electron source module in the first vacuum chamber, and applying a preset current and a preset voltage to the Schottky electron source module through a power-on device; The Schottky electron source module generates electrons, and the electron beam hits the fluorescent screen to emit light. The shape of the electron beam on the fluorescent screen and the current to ground are observed by a camera to roughly identify whether the current and voltage parameters are appropriate; When the current and voltage parameters are initially appropriate, the vacuum valve is opened, and the transport structure transports the Schottky electron source module to the second vacuum chamber; The scanning electron microscope directly observes the actual morphology evolution process of the tip surface of the Schottky electron source module in the second vacuum chamber, thereby accurately judging whether the current and voltage parameters are appropriate.

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