A method for fabricating an ion source grid

Abstract

This invention discloses a method for processing an ion source grid, which includes the following steps: processing a molybdenum plate into a grid; and heating the grid to above 1200°C at a heating rate ≥20°C / min for vacuum annealing to complete the grid processing. In this invention, by rapidly heating the grid to above 1200°C for vacuum annealing, the processed grid can be recrystallized and annealed, removing internal stress and causing recrystallization of the microstructure near the deformed grid holes. This improves the microstructure, increases uniformity, enhances grid stability, and ultimately extends the service life of the ion source grid. Furthermore, the vacuum annealing treatment before and after processing in this invention improves the processing performance, mechanical and physical properties of the molybdenum plate, thereby further improving the grid's performance, stability, and service life.

Description

Technical Field

[0001] This invention relates to a method for fabricating an ion source grid. Background Technology

[0002] The ion source grid (ion beam optical system) is the core component of a grid-type ion source, and its stability determines the stability and reliability of the ion beam extracted from the ion source. Currently, the main materials used for fabricating ion source grids are molybdenum and graphite. By fabricating molybdenum or graphite into a mesh electrode and placing it at the front end of the ion source outlet, the ion beam can be extracted from the ion source discharge chamber, giving the ion beam a certain spatial concentration and spatial distribution pattern. Specifically, the ion source grid used in grid-type ion source devices is usually a two- or three-layer structure, and the distance between the grids is generally between 1mm and 2mm. Figure 1 As shown, a grid-type ion source device assembled from three layers of ion source grids includes a screen grid, an accelerating grid, and a ground grid (with zero potential). The ion beam passes sequentially through the screen grid, accelerating grid, and ground grid to ultimately form an ion beam with a certain spatial concentration. For grid-type ion source devices, the distance between each grid and the relative deflection angle of the apertures on each grid have a significant impact on their operational stability and the ability to control the ion beam. For example, ion beam formation usually requires high temperatures. However, under high-temperature conditions, the ion source grid is prone to thermal expansion and deformation. In particular, deformation is more likely to occur near the grid apertures, and the adverse effects are more severe. The end result is that the distance between each grid and the relative deflection angle of the apertures on each grid will change, which can easily alter the beam extraction characteristics and degrade the beam quality. In other words, the use of existing ion source grids under high-temperature conditions can easily lead to a decrease in the operational stability of the grid-type ion source device and a decrease in the ability to control the ion beam.

[0003] Currently, in order to ensure the working performance of ion sources, the common improvement method used in the use of ion sources is to remove the grid and reinstall it. However, this method will inevitably reduce production efficiency and increase installation and maintenance costs. Moreover, the installation and debugging of the ion source grid both rely on the experience of the operators, which will ultimately lead to low assembly and adjustment efficiency and difficulty in consistently meeting the assembly and adjustment accuracy and repeatability standards due to the different experience of the operators.

[0004] Furthermore, no researchers have proposed any improvement schemes to address the issue of ion source grids easily deforming under high-temperature conditions, leading to poor performance or failure. Meanwhile, the molybdenum plates used to fabricate ion source grids contain numerous crystal defects, forming subgrain boundaries and cellular structures, exhibiting typical fibrous deformable microstructure characteristics. This results in the molybdenum plates still having defects in mechanical, physical, and processing properties that do not meet the requirements for grid use, leading to decreased stability and lifespan of the fabricated grids. Therefore, obtaining an ion source grid with good stability and long lifespan is of great significance for improving the quality of ion beams. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for processing ion source grids with good stability and long service life, which addresses the shortcomings of the prior art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for fabricating an ion source grid includes the following steps:

[0008] S1. Process molybdenum plates into a grid;

[0009] S2. Under the condition of heating rate ≥20℃ / min, heat the grid to above 1200℃ for vacuum annealing to complete the processing of the grid.

[0010] In a further improvement to the above processing method, in step S2, the heating rate is 20℃ / min to 100℃ / min.

[0011] In a further improvement to the above processing method, in step S2, the temperature is controlled at 1200℃~1250℃ during the vacuum annealing process.

[0012] In a further improvement to the above processing method, the vacuum annealing process in step S2 is performed for 1 to 2 hours.

[0013] In a further improvement to the above processing method, in step S2, the vacuum degree is controlled to be ≤1E during the vacuum annealing process. -3 Pa.

[0014] In a further improvement to the above processing method, step S1 further includes the following treatment before the molybdenum plate is processed into a grid: the molybdenum plate is heated to above 1200°C for annealing pretreatment at a heating rate ≥100°C / min to complete the pretreatment of the molybdenum plate.

[0015] In a further improvement to the above processing method, the heating rate is 100℃ / min to 1000℃ / min.

[0016] In a further improvement to the above processing method, the temperature during the annealing pretreatment is controlled at 1200℃~1250℃.

[0017] In a further improvement to the above processing method, the annealing pretreatment time is 1 to 2 hours.

[0018] A further improvement to the above processing method is that the vacuum degree is controlled to be ≤1E during the annealing pretreatment process. -3 Pa.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] (1) To address the shortcomings of existing ion source grids, such as poor stability and deteriorating service life, this invention creatively proposes a processing method for ion source grids. By rapidly heating the grid (e.g., at a heating rate of 20℃ / min to 100℃ / min) to above 1200℃ (e.g., between 1200℃ and 1250℃) and performing vacuum annealing, the processed grid can be recrystallized and annealed, removing internal stress and causing recrystallization of the microstructure near the deformed grid holes. This improves the microstructure, increases uniformity, enhances grid stability, and ultimately extends the service life of the ion source grid. Specifically, recrystallization cannot be achieved when the annealing temperature is below 1200℃, and when the temperature rises above 1250℃, the grains become coarse, affecting the grid's mechanical properties and consequently its quality.

[0021] (2) In the processing method of this invention, before processing the molybdenum plate into a grid, a pre-annealing treatment is also included. This is achieved by rapidly heating the molybdenum plate (e.g., at a heating rate of 100℃ / min to 1000℃ / min) to above 1200℃ (e.g., between 1200℃ and 1250℃) and then performing vacuum annealing. This process causes recovery and recrystallization within the molybdenum plate, refines the internal grain shape, reduces deformation resistance, and thus improves the forming deformation structure. It also results in an equiaxed grain structure and uniform isotropy, giving the molybdenum plate good mechanical and physical properties and improving the processing performance of the grid. More importantly, the vacuum annealing treatment before and after processing in this invention regulates the microstructure of the molybdenum plate, refines the grains, improves the forming deformation structure, obtains an equiaxed grain structure and uniform isotropy, increases uniformity, and removes internal stress. This improves the processing performance, mechanical and physical properties of the molybdenum plate, thereby further improving the grid's performance, stability, and service life. Attached Figure Description

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the working process of a focusing ion source grid.

[0024] Figure 2 This is a schematic diagram of the fabrication process of the ion source grid in Embodiment 1 of the present invention. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0026] The materials and instruments used in the following examples are all commercially available.

[0027] Example 1:

[0028] A method for fabricating an ion source grid, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps:

[0029] (1) Using rolled molybdenum plates as raw materials, the plates are processed into blanks.

[0030] (2) Place the blank sheet in the annealing furnace and evacuate it to a vacuum level of 1E. -3 At the Pa level, the blank material is heated to 1200℃ at a heating rate of 600℃ / min, held for 2 hours, and then cooled in the furnace under nitrogen atmosphere to complete the pretreatment of the molybdenum plate.

[0031] (3) According to the established processing technology benchmark, the pre-annealed blank sheet is pressed, hole-processed and fine-processed to obtain a grid. Specifically, it is made into a screen grid, acceleration grid and ground grid as needed.

[0032] (4) Place each grid blank in an annealing furnace and evacuate to a vacuum level of 1E. -3 At the Pa level, the grid is heated to 1200℃ at a heating rate of 40℃ / min, held for 2 hours, and then cooled in a furnace under nitrogen atmosphere to complete the vacuum annealing treatment.

[0033] (5) The grid after vacuum annealing is surface treated and assembled into an ion source grid.

[0034] Example 2:

[0035] A method for fabricating an ion source grid includes the following steps:

[0036] (1) Using rolled molybdenum plates as raw materials, the plates are processed into blanks.

[0037] (2) Place the blank sheet in the annealing furnace and evacuate it to a vacuum level of 1E. -3 At the Pa level, the blank material is heated to 1250℃ at a heating rate of 300℃ / min, held for 1 hour, and then cooled in the furnace under nitrogen atmosphere to complete the annealing pretreatment of the molybdenum plate.

[0038] (3) According to the established processing technology benchmark, the pre-annealed blank sheet is pressed, hole-processed and fine-processed to obtain a grid. Specifically, it is made into a screen grid, acceleration grid and ground grid as needed.

[0039] (4) Place each grid blank in an annealing furnace and evacuate to a vacuum level of 1E. -3 At the Pa level, the grid is heated to 1250℃ at a heating rate of 60℃ / min, held for 1.5h, and then cooled in the furnace under nitrogen atmosphere to complete the vacuum annealing treatment.

[0040] (5) The grid after vacuum annealing is surface treated and assembled into an ion source grid.

[0041] Example 3:

[0042] A method for fabricating an ion source grid includes the following steps:

[0043] (1) Using rolled molybdenum plates as raw materials, the plates are processed into blanks.

[0044] (2) Place the blank sheet in the annealing furnace and evacuate it to a vacuum level of 1E. -3 At the Pa level, the blank material is heated to 1200℃ at a heating rate of 500℃ / min, held for 1.5h, and then cooled in the furnace under nitrogen atmosphere to complete the annealing pretreatment of molybdenum plates before processing.

[0045] (3) According to the established processing technology benchmark, the pre-annealed blank sheet is pressed, hole-processed and fine-processed to obtain a grid. Specifically, it is made into a screen grid, acceleration grid and ground grid as needed.

[0046] (4) Place each grid blank in an annealing furnace and evacuate to a vacuum level of 1E. -3 At the Pa level, the grid is heated to 1200℃-1250℃ at a heating rate of 20℃ / min to 100℃ / min, held for 1h-2h, and then cooled in a furnace under nitrogen atmosphere to complete the vacuum annealing treatment.

[0047] (5) The grid after vacuum annealing is surface treated and assembled into an ion source grid.

[0048] Example 4:

[0049] A method for fabricating an ion source grid includes the following steps:

[0050] (1) Using rolled molybdenum plates as raw materials, the plates are processed into blanks.

[0051] (2) According to the established processing technology benchmark, the blank material is pressed, hole-processed and precision-processed to obtain the grid. Specifically, it is made into screen grid, acceleration grid and ground grid as needed.

[0052] (3) Place each grid blank in an annealing furnace and evacuate to a vacuum level of 1E. -3 At the Pa level, the grid is heated to 1200℃ at a heating rate of 400℃ / min, held for 2 hours, and then cooled in a furnace under nitrogen atmosphere to complete the vacuum annealing process.

[0053] (4) The grid after vacuum annealing is surface treated and assembled into an ion source grid.

[0054] Comparative Example 1

[0055] A method for fabricating an ion source grid includes the following steps:

[0056] (1) Using rolled molybdenum plates as raw materials, the plates are processed into blanks.

[0057] (2) According to the established processing technology benchmark, the blank material is pressed, hole-processed and precision-processed to obtain the grid. Specifically, it is made into screen grid, acceleration grid and ground grid as needed.

[0058] (3) The grid is surface treated and assembled into an ion source grid.

[0059] The lifespan of the ion source grids prepared in Examples 1-4 and Comparative Example 1 was tested, and the results are shown in Table 1.

[0060] Table 1. Service life of ion source grids prepared by different processing techniques

[0061] Service life Example 1 5760h Example 2 5040h Example 3 5240h Example 4 4320h Comparative Example 1 1008h

[0062] As shown in Table 1, compared with the processing technology without annealing, the processing technology of the present invention can significantly improve the service life of the ion source grid by performing vacuum annealing on the grid. At the same time, by performing vacuum annealing on both the molybdenum plate and the grid before and after processing, the service life of the ion source grid can be further improved.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for fabricating an ion source grid, characterized in that, Includes the following steps: S1. Process molybdenum plates into a grid; S2. Under the condition of heating rate of 20℃ / min~100℃ / min, the grid is heated to 1200℃~1250℃ for vacuum annealing to complete the processing of the grid.

2. The processing method according to claim 1, characterized in that, In step S2, the vacuum annealing process takes 1 to 2 hours.

3. The processing method according to claim 2, characterized in that, In step S2, the vacuum degree is controlled to be ≤1E during the vacuum annealing process. -3 Pa.

4. The processing method according to any one of claims 1 to 3, characterized in that, In step S1, the molybdenum plate is further subjected to the following treatment before being processed into a grid: the molybdenum plate is heated to above 1200°C for annealing pretreatment at a heating rate ≥100°C / min to complete the pretreatment of the molybdenum plate.

5. The processing method according to claim 4, characterized in that, The heating rate is 100℃ / min to 1000℃ / min.

6. The processing method according to claim 5, characterized in that, The temperature is controlled at 1200℃~1250℃ during the annealing pretreatment process.

7. The processing method according to claim 6, characterized in that, The annealing pretreatment time is 1 hour to 2 hours.

8. The processing method according to claim 7, characterized in that, During the annealing pretreatment process, the vacuum level is controlled to be ≤1E. -3 Pa.

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