Electron beam screening structure and preparation method thereof

Abstract

The invention discloses an electron beam screening structure and a preparation method thereof. The screening structure comprises a transmission hole, a conical mesh area and a mechanical fixing area. The transmission hole is located in the center of the conical mesh area and serves as a space for an incident electron beam to penetrate through. The cone vertex of the cone-shaped mesh area is located at the incidence point of an original incident electron beam on a sample, and the cone bottom circumference of the cone-shaped mesh area is fixedly connected with the mechanical fixing area to form an electron beam transmission channel with a large upper part and a small lower part; the conical mesh area is used for screening electron beams in the transmission direction, so that back-propagation back-scattering electrons generated when original incident electron beams collide with a sample penetrate through the conical mesh area, and new back-scattering electrons generated when the back-propagation back-scattering electrons collide with mechanical parts located on the bottom surfaces of conical meshes again are blocked; the mechanical fixing area is used for installing and fixing the electron beam screening structure and forming electric contact. The screening device has the advantages of being compact in structure, simple in principle, high in screening quality, good in blocking effect and the like, and the quality of electron beam exposure plotting is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the field of electronic technology, and in particular relates to an electron beam screening structure and a preparation method thereof. Background Art

[0002] The electron beam emitted by the electron source often has a single transmission direction after being regulated by structures such as accelerating electrodes, focusing electrodes, and electromagnetic lenses. However, when this type of electron beam interacts with other objects, it will produce many other particles. The number, energy, and transmission direction of these particles vary from material to material. Some of them will interfere with the original effect of the electron beam and need to be eliminated in a specific way.

[0003] Taking the electron beam exposure machine as an example, the electron beam exposure machine generates an electron beam through the cathode, accelerates it through the anode to produce an electron beam with energy of tens or hundreds of kilovolts, and then focuses it through the electromagnetic lens and transmits it to the semiconductor material for graphic exposure. Due to its fine processing capabilities, it has become an important instrument in the integrated circuit industry and micro-nano scientific research field.

[0004] When the electron beam acts on the sample, it will generate secondary photons and electrons such as X-ray radiation, cathode fluorescence, secondary electrons, and backscattered electrons. Among them, backscattered electrons are electrons generated by the collision between the electron beam and the sample atomic nucleus, and their energy can be close to the energy of the incident electron. Due to the randomness of the collision, backscattered electrons will be emitted in all directions. After emission, the backscattered electrons will interact with the mechanical parts that control the electron beam to generate a large number of backscattered electrons with energy close to that of the incident electron. After secondary scattering, a considerable part of the backscattered electrons will be incident on the semiconductor material to be exposed again. This part of the backscattered electrons is completely random and has extremely low controllability, which will seriously interfere with the exposure and mapping of the original emitted electron beam. Therefore, the electron beam must be screened and controlled. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an electron beam screening structure and a preparation method thereof with compact structure, simple principle and good blocking effect in view of the deficiencies in the prior art.

[0006] To achieve the above object, the present invention can adopt the following technical solutions: An electron beam screening structure comprises: a transmission hole, a conical mesh area and a mechanical fixing area; the transmission hole is located at the center of the conical mesh area to serve as a space for an incident electron beam to pass through; the cone vertex of the conical mesh area is located at the incident point of the original incident electron beam on a sample, and the cone bottom circumference of the conical mesh area is connected and fixed to the mechanical fixing area to form an electron beam transmission channel with a larger top and a smaller bottom; the conical mesh area is used to realize electron beam transmission direction screening, so that reverse propagation backscattered electrons generated when the original incident electron beam collides with the sample pass through, and new backscattered electrons generated by the reverse propagation backscattered electrons colliding again with mechanical parts located at the bottom of the conical mesh are blocked; the mechanical fixing area is used to realize the installation and fixation of the electron beam screening structure and form electrical contact. As a further improvement of the present invention, the diameter of the transmission hole is 1 mm to 2 mm. As a further improvement of the present invention, the circumferential diameter of the cone bottom of the conical mesh area is 2 cm to 20 cm, and the thickness is 1 mm to 5 mm; the middle area of ​​the conical mesh area is distributed with a variety of holes extending from the cone bottom to the cone top, the diameter of the inscribed circle of the hole is 0.3 mm to 0.8 mm, and the width of the hole side wall is 0.05 mm to 0.1 mm. As a further improvement of the present invention, the outermost layer of the conical mesh area is wrapped with a layer of conductive material with a light atomic number. As a further improvement of the present invention, the cone-shaped mesh area uses carbon material, aluminum material, copper material or titanium material as a skeleton, and a carbon material, aluminum material or boron material film is attached to the skeleton. As a further improvement of the present invention, the conical mesh area is integrally formed, or is formed by laminating and casting multiple layers of thin sheets.

[0007] As a further improvement of the present invention, the conical mesh area is provided with a notch area to be used as an optical detection light path channel or an electronic signal detection channel or to screen the transmission direction of backscattered electrons in a partial area. As a general technical concept, the present invention also provides a method for preparing the above-mentioned electron beam screening structure, comprising the following steps: Step S1, determining the incident electron beam energy and the electron beam incident point; Step S2, determining the distance between the screening structure and the electron beam incident point, and the thickness and radius of the screening structure according to the incident point; Step S3, taking the incident point as the cone vertex, designing the rotation angle step length from the cone height to the cone generatrix according to the process requirements, and constructing a two-dimensional cone hole; Step S4, preparing a conical mesh area by integrally forming a carbon material or by copper mesh supporting a carbon film and performing stacking manufacturing, and obtaining a complete electron beam screening structure.

[0008] As a further improvement of the present invention, in step S4, when the conical mesh area is prepared by integrally forming carbon materials, the following steps are included: Step S41, taking the electron beam incident line path as the axis, rotating the two-dimensional cone mesh design parallel to the paper surface by 360° to construct a three-dimensional cone hole; Step S42, according to the preset screening structure radius, within the thickness range, design a two-dimensional surface, take the electron beam incident line path as the axis, design the two-dimensional surface into a circular array arrangement, cut the three-dimensional conical holes and connect them at the same time, and construct a three-dimensional conical mesh; Step S43, designing mechanical connection holes in the mechanical fixing area; Step S44: output the three-dimensional design, and form the 3D carbon material integrated printing structure. As a further improvement of the present invention, in step S4, when the conical mesh area is prepared by using a copper mesh to support the carbon film coating and performing a lamination manufacturing method, the following steps are included: Step S41, according to functional requirements, cut and screen the structure in layers to determine the radius of the circle where the two-dimensional conical holes are located at different Z axes; Step S42, according to the preset radius of the circle where the two-dimensional conical holes are located, design connection lines for the two-dimensional conical holes in different layers, and arrange them in a circular array, cut the two-dimensional conical holes and connect them at the same time, so as to construct a two-dimensional conical mesh; Step S43, performing Monte Carlo simulation according to the electron incident energy, and the thickness of the carbon layer that the electrons cannot penetrate is used to determine the carbon film coating thickness; Step S44, processing the copper substrate by laser cutting; Step S45, after shielding the mechanical fixing area, a carbon film is deposited multiple times by vapor deposition to obtain a carbon film of a preset thickness, and the carbon film is coated on the copper material; Step S46: Connect the multi-layer copper mesh by laser welding to construct a three-dimensional cone mesh to obtain a complete screening structure.

[0009] Compared with the prior art, the advantages of the present invention are: The electron beam screening structure and the preparation method thereof of the present invention form a compact screening structure through a transmission hole, a conical mesh area and a mechanical fixing area. Specifically, the mechanical fixing area is used to realize the installation and fixing of the electron beam screening structure to electronic equipment such as a scanning electron microscope, a transmission electron microscope or an electron beam exposure machine, and form electrical contact. The cone vertex of the conical mesh area is located at the point where the original incident electron beam contacts and interacts with the sample, and the cone bottom of the conical mesh area is connected and fixed to the mechanical fixing area, forming an electron beam transmission channel with a larger top and a smaller bottom. The transmission hole is located at the center of the conical mesh area, forming a space for the incident electron beam to pass through, and the transmission hole does not block anything. The invention meets the requirements of electron beam exposure machines, scanning electron microscopes and other instruments for emitting electron beams to incident on samples; the transmission direction of the electron beam is screened by using the conical mesh area, so that the reverse-propagating backscattered electrons generated when the original incident electron beam collides with the sample can pass smoothly, while the new backscattered electrons generated by the re-collision between the reverse-propagating backscattered electrons and other mechanical parts located at the bottom of the cone of the conical mesh area are blocked by the conical mesh area; and the use of lightweight atomic number materials with low scattering probability improves the controllability of backscattered electrons, avoids the backscattered electrons from being incident on the semiconductor material to be exposed again, and improves the exposure and mapping quality of the original emitted electron beam. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram of a top view of a 1 / 4 electron beam screening structure in a specific embodiment of the present invention; Figure 2 It is a schematic diagram of the side view of the electron beam screening structure in a specific embodiment of the present invention; Figure 3 A schematic diagram of the working principle of the electron beam screening structure in a specific embodiment of the present invention; Figure 4 It is a schematic diagram of the principle of determining the relevant parameters of the screening structure according to the incident point position during the preparation process of the electron beam screening structure in a specific embodiment of the present invention; Figure 5 It is a schematic diagram of the principle of constructing a two-dimensional cone-shaped hole in the process of preparing an electron beam screening structure in a specific embodiment of the present invention; Figure 6 It is a schematic diagram of the principle of constructing a three-dimensional cone-shaped hole in the process of preparing an electron beam screening structure in a specific embodiment of the present invention; Figure 7 It is a schematic diagram of the connection of the circular array of the two-dimensional surface in the process of preparing the electron beam screening structure in a specific embodiment of the present invention; Figure 8 It is a schematic diagram of the circumferential array connection of connecting wires in the process of preparing the electron beam screening structure in a specific embodiment of the present invention; Fig. 9 It is a top view of a 1 / 4 single-layer structure prepared by a lamination method in a specific embodiment of the present invention; Legend: 1. Transmission hole; 2. Conical mesh area; 3. Mechanical fixing area; 4. Mechanical parts. DETAILED DESCRIPTION

[0010] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0011] In the description of the present invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0012] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0013] Example like Figure 1 As shown, the electron beam screening structure of the present invention comprises: a transmission hole 1, a conical mesh area 2 and a mechanical fixing area 3. The transmission hole 1 is located at the center of the conical mesh area 2, serving as a space for the incident electron beam to pass through. The cone vertex of the conical mesh area 2 is located at the incident point of the original incident electron beam on the sample, and the cone bottom circumference of the conical mesh area 2 is connected and fixed to the mechanical fixing area 3, forming an electron beam transmission channel with a larger top and a smaller bottom. Figure 2 and Figure 3 As shown, the conical mesh area 2 is used to realize the screening of the electron beam transmission direction, so that the reverse propagation backscattered electrons generated when the original incident electron beam collides with the sample pass through, and the new backscattered electrons generated by the collision between the reverse propagation backscattered electrons and the mechanical part 4 located at the bottom of the cone of the conical mesh area 2 are blocked. The mechanical fixing area 3 is used to realize the installation and fixation of the electron beam screening structure and form electrical contact. Positioning holes, threaded holes and other structures can be added according to the actual situation of the equipment. It can be understood that the mechanical part 4 can specifically be a mechanical structure such as a lens barrel housing.

[0014] In this embodiment, a compact screening structure is formed by the transmission hole 1, the conical mesh area 2 and the mechanical fixing area 3. Specifically, the mechanical fixing area 3 is used to realize the installation and fixation of the electron beam screening structure to electronic equipment such as a scanning electron microscope, a transmission electron microscope or an electron beam exposure machine, and form electrical contact; the cone vertex of the conical mesh area 2 is located at the point where the original incident electron beam contacts and interacts with the sample, and the cone bottom circumference of the conical mesh area 2 is connected and fixed to the mechanical fixing area 3, that is, an electron beam transmission channel with a larger top and a smaller bottom is formed, and the transmission hole 1 is located at the center of the conical mesh area 2, forming a space for the incident electron beam to pass through, and the transmission hole 1 does not block anything, thereby meeting the requirements of instruments such as electron beam exposure machines and scanning electron microscopes to emit electron beams to incident on samples. By utilizing the conical mesh region 2 to screen the electron beam transmission direction, the reverse-propagating backscattered electrons generated when the original incident electron beam collides with the sample can pass smoothly, while the new backscattered electrons generated by the re-collision between the reverse-propagating backscattered electrons and the mechanical part 4 located at the bottom of the cone of the conical mesh region 2 are blocked by the conical mesh region 2, thereby improving the controllability of the backscattered electrons after secondary scattering, avoiding the backscattered electrons from being incident on the semiconductor material to be exposed again, and improving the exposure and mapping quality of the original emitted electron beam.

[0015] In this embodiment, the diameter of the transmission hole 1 is 1 mm to 2 mm. In this embodiment, the direction of the incident electron beam is defined as the Z axis.

[0016] In this embodiment, the overall morphology of the conical mesh area 2 is similar to the bottom of a cone in side view, and the area covered by the circumference of the cone bottom is 2 cm to 20 cm, and the thickness is 1 mm to 5 mm. Figure 1 As shown, a plurality of holes extending from the cone bottom to the cone top are distributed in the middle area of ​​the cone-shaped mesh area 2, the diameter of the inscribed circle of the hole is 0.3 mm to 0.8 mm, and the width of the hole side wall is 0.05 mm to 0.1 mm. In this embodiment, the conical mesh area 2 mainly includes three characteristics, namely high conductivity, low collision rate and high screening. The outermost layer of the conical mesh area 2 is wrapped with a layer of conductive material with a light atomic number, such as boron, carbon, aluminum and other materials. The high conductivity allows a small number of electrons incident on the conical mesh area 2 to be quickly transferred away, and the accumulated charge will not affect the incident electron beam, and the heat generation is small. In addition, the light atomic number means that the atomic real part is small, so the probability of collision when this part of the material interacts with the backscattered electrons is small, thereby reducing the possibility of generating backscattered electrons again. Finally, it is high blocking. When the original incident electron beam collides with the sample, it is randomly scattered. Therefore, it will travel in the opposite direction of the original incident electron beam on the Z axis and diverge in all directions in the XY plane. Since the conical mesh area 2 extends from the electron beam emission end to the landing sample end, it actually forms a transmission channel with a large top and a small bottom, so that the backscattered electrons propagating in the reverse direction can pass through each hole, but when it collides with the mechanical part 4 again, most of the new backscattered electrons will be blocked.

[0017] In this embodiment, the conical mesh area 2 can be made of high-strength carbon material or aluminum material, or a non-ferromagnetic metal such as copper or titanium can be used as a skeleton, and then a carbon material, aluminum material, boron material, etc. is attached to the skeleton.

[0018] Furthermore, the conical mesh area 2 is integrally formed, or cast by laminating multiple layers of thin sheets. The conical mesh area 2 adopts a circular symmetric design, which is convenient for drawing, designing, manufacturing and processing of the graphics.

[0019] In this embodiment, a notch area can be added to the conical mesh area 2 to be used as an optical detection light path channel or an electronic signal detection channel or to screen the transmission direction of backscattered electrons in a partial area.

[0020] In this embodiment, a preparation method applicable to the above-mentioned electron beam screening structure is also provided, comprising the following steps: Step S1, determining the energy of the incident electron beam and the incident point of the electron beam; the energy of the incident electron beam is generally between several thousand volts and several hundred kilovolts.

[0021] Step S2, determining the distance between the screening structure and the electron beam incident point, the thickness and radius of the screening structure according to the incident point; Figure 4 shown.

[0022] Step S3, taking the incident point as the cone vertex, designing the rotation angle step length from the cone height to the cone generatrix according to the process requirements, and constructing a two-dimensional cone hole; Figure 5 shown.

[0023] Step S4, preparing the conical mesh area 2 by integrally forming a carbon material or by copper mesh supporting a carbon film and performing stacking manufacturing, and obtaining a complete electron beam screening structure.

[0024] In step S4 of this embodiment, when the conical mesh area 2 is prepared by integrally forming carbon materials, the following steps are included: Step S41, taking the electron beam incident line path as the axis, the two-dimensional cone mesh design parallel to the paper surface is rotated 360° to construct a three-dimensional cone hole; Figure 6 shown.

[0025] Step S42, according to the preset screening structure radius, within the thickness range, design a two-dimensional surface, take the electron beam incident line path as the axis, design the two-dimensional surface into a circular array arrangement, cut the three-dimensional conical holes and connect them at the same time, and construct a three-dimensional conical mesh; Figure 7 shown.

[0026] Step S43 , designing mechanical connection holes in the mechanical fixing area 3 .

[0027] Step S44: output the three-dimensional design, and form the 3D carbon material integrated printing structure.

[0028] In step S4 of this embodiment, when the conical mesh area 2 is prepared by using a copper mesh to support the carbon film coating and performing a lamination manufacturing method, the following steps are included: Step S41: According to functional requirements, the screening structure is cut in layers to determine the radius of the circle where the two-dimensional conical holes are located at different Z axes.

[0029] Step S42, according to the preset radius of the circle where the two-dimensional conical holes are located, design connection lines for the two-dimensional conical holes of different layers, and arrange them in a circular array, cut the two-dimensional conical holes and connect them at the same time, and construct a two-dimensional conical mesh; Figure 8 shown.

[0030] Step S43: Monte Carlo simulation is performed according to the electron incident energy, and the thickness of the carbon layer that the electrons cannot penetrate is used to determine the carbon film coating thickness. For example, for a 30 keV incident electron beam, the carbon film coating thickness is above 15 microns.

[0031] Step S44, processing the copper substrate by femtosecond laser cutting or other methods; Fig. 9 shown.

[0032] Step S45 , after shielding the mechanical fixing area 3 , a carbon film is deposited multiple times by plasma enhanced chemical vapor deposition or the like to obtain a carbon film of a preset thickness, and the carbon film is coated on the copper material.

[0033] Step S46: Connect the multi-layer copper mesh by laser welding to construct a three-dimensional cone mesh to obtain a complete screening structure.

[0034] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the spirit and technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still fall within the scope of protection of the technical solutions of the present invention.

Claims

1. An electron beam screening structure, characterized in that: include: A transmission hole (1), a conical mesh area (2) and a mechanical fixing area (3); the transmission hole (1) is located at the center of the conical mesh area (2) to serve as a space through which an incident electron beam passes; the cone vertex of the conical mesh area (2) is located at the incident point of the original incident electron beam on the sample, and the cone bottom circumference of the conical mesh area (2) is connected and fixed to the mechanical fixing area (3) to form an electron beam transmission channel with a larger top and a smaller bottom; the conical mesh area (2) is used to realize electron beam transmission direction screening, so that the reverse propagation backscattered electrons generated when the original incident electron beam collides with the sample pass through, and the new backscattered electrons generated by the reverse propagation backscattered electrons colliding again with the mechanical part (4) located at the cone bottom surface of the conical mesh area (2) are blocked; the mechanical fixing area (3) is used to realize the installation and fixation of the electron beam screening structure and form electrical contact.

2. The electron beam screening structure according to claim 1, characterized in that: The transmission hole (1) has a diameter of 1 mm to 2 mm.

3. The electron beam screening structure according to claim 2, characterized in that: The cone-shaped mesh area (2) has a cone bottom circumference diameter of 2 cm to 20 cm and a thickness of 1 mm to 5 mm; a plurality of holes extending from the cone bottom to the cone top are distributed in the middle area of ​​the cone-shaped mesh area (2), the diameter of the inscribed circle of the hole is 0.3 mm to 0.8 mm, and the width of the hole side wall is 0.05 mm to 0.1 mm.

4. The electron beam screening structure according to claim 3, characterized in that: The outermost layer of the conical mesh area (2) is wrapped with a layer of conductive material with a light atomic number.

5. The electron beam screening structure according to claim 3, characterized in that: The cone-shaped mesh area (2) uses carbon material, aluminum material, copper material or titanium material as a skeleton, and a carbon material, aluminum material or boron material film is attached to the skeleton.

6. The electron beam screening structure according to claim 5, characterized in that: The conical mesh area (2) is integrally formed, or is formed by laminating and casting multiple layers of thin sheets.

7. The electron beam screening structure according to any one of claims 1 to 6, characterized in that: The conical mesh area (2) is provided with a notch area to be used as an optical detection light path channel or an electronic signal detection channel or to screen the transmission direction of backscattered electrons in a partial area.

8. A method for preparing an electron beam screening structure according to any one of claims 1 to 7, characterized in that: The following steps are included; Step S1, determining the incident electron beam energy and the electron beam incident point; Step S2, determining the distance between the screening structure and the electron beam incident point, and the thickness and radius of the screening structure according to the incident point; Step S3, taking the incident point as the cone vertex, designing the rotation angle step length from the cone height to the cone generatrix according to the process requirements, and constructing a two-dimensional cone hole; Step S4, preparing the conical mesh area (2) by integrally forming a carbon material or by copper mesh supporting a carbon film and performing a stacking manufacturing method, and obtaining a complete electron beam screening structure.

9. The preparation method according to claim 8, characterized in that: In the step S4, when the conical mesh area (2) is prepared by integrally forming a carbon material, the steps include: Step S41, taking the electron beam incident line path as the axis, rotating the two-dimensional cone mesh design parallel to the paper surface by 360° to construct a three-dimensional cone hole; Step S42, according to the preset screening structure radius, within the thickness range, design a two-dimensional surface, take the electron beam incident line path as the axis, design the two-dimensional surface into a circular array arrangement, cut the three-dimensional conical holes and connect them at the same time, and construct a three-dimensional conical mesh; Step S43, designing a mechanical connection hole in the mechanical fixing area (3); Step S44: output the three-dimensional design, and form the 3D carbon material integrated printing structure.

10. The preparation method according to claim 8, characterized in that: In the step S4, when the conical mesh area (2) is prepared by using a copper mesh supporting carbon film coating and performing a lamination manufacturing method, the following steps are included: Step S41, according to functional requirements, cut and screen the structure in layers to determine the radius of the circle where the two-dimensional conical holes are located at different Z axes; Step S42, according to the preset radius of the circle where the two-dimensional conical holes are located, design connection lines for the two-dimensional conical holes in different layers, and arrange them in a circular array, cut the two-dimensional conical holes and connect them at the same time, so as to construct a two-dimensional conical mesh; Step S43, performing Monte Carlo simulation according to the electron incident energy, and the thickness of the carbon layer that the electrons cannot penetrate is used to determine the carbon film coating thickness; Step S44, processing the copper substrate by laser cutting; Step S45, after shielding the mechanical fixing area (3), a carbon film is deposited multiple times by vapor deposition to obtain a carbon film of a preset thickness, and the carbon film is coated on the copper material; Step S46: Connect the multi-layer copper mesh by laser welding to construct a three-dimensional cone mesh to obtain a complete screening structure.

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