Variable diameter focusing assembly, RF acceleration section and ion implanter

Abstract

The present invention belongs to the field of semiconductor technology, and discloses a variable diameter focusing assembly, a radio frequency acceleration section, and an ion implanter. The variable diameter focusing assembly includes a plurality of focusing units arranged along the direction of movement of the ion beam, the plurality of focusing units are arranged with alternating polarities, the ion beam channel radius on the plurality of focusing units gradually decreases along the direction of movement of the ion beam, and the ion beam channel radius on the rearmost focusing unit is greater than or equal to the ion beam channel radius on the accelerator downstream of the variable diameter focusing assembly. The radio frequency acceleration section includes a bunching assembly, the above-mentioned variable diameter focusing assembly, and an accelerator. The ion implanter includes an ion source, a mass analyzer, and the above-mentioned radio frequency acceleration section. The present invention can shape an ion beam that is excessively divergent in the radial direction through the bunching assembly, reduce the loss caused by ion beam diffusion, improve the transmission efficiency of the ion beam, and is applicable to ions of all mass-to-charge ratios.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more specifically, to a variable diameter focusing component, a radio frequency acceleration section and an ion implanter. Background Art

[0002] In the semiconductor industry, high-energy ion implanters accelerate ion beams to more than 1 MeV and then implant them into the surface of silicon wafers. The high-energy ion accelerators currently used use RF (Radio Frequency) acceleration structures. Figure 1 As shown in FIG. 1 , the ion implanter mainly includes an ion source 101, a mass analyzer 102 (or screening magnet) and a radio frequency acceleration section 110, wherein the radio frequency acceleration section 110 includes a bunching assembly 103, a focusing assembly 104 and an accelerator 105. After the beam generated by the ion source 101 passes through the mass analyzer 102, ions with a specific charge-to-mass ratio are screened out and enter the radio frequency acceleration section 110. The bunching assembly 103 in the radio frequency acceleration section 110 is very important for improving the overall beam current intensity. The three-dimensional structure of the bunching assembly 103 is shown in FIG. Figure 2 As shown. The focusing component 103 mainly includes a first ground electrode 131, a second ground electrode 133 and a first accelerating electrode 132 between the first ground electrode 131 and the second ground electrode 133. The first accelerating electrode 132 is connected to a radio frequency power supply with a fixed frequency to generate an alternating electric field. The uniform ion beam will be accelerated or decelerated when passing through a first gap 134a between the first ground electrode 131 and the first accelerating electrode 132 and a second gap 134b between the first accelerating electrode 132 and the second ground electrode 133. Acceleration or deceleration depends on whether the electric field of the first accelerating electrode 132 is positive or negative when the ion beam passes through the gap. In one radio frequency cycle, some ions will be decelerated and some ions will be accelerated. The accelerated ions catch up with the previously decelerated ions to form a tight bunch in space. The three-dimensional structure of the focusing component 104 is shown in FIG. Figure 2 As shown, the focusing assembly 104 includes two focusing units - a first focusing unit 1041 and a second focusing unit 1042. Each focusing unit includes a third ground electrode 141, a fourth ground electrode 143, and a quadrupole lens 142 between the third ground electrode 141 and the fourth ground electrode 143. After the ion cluster beam of the bunching assembly 103 passes through the first focusing unit 1041 and the second focusing unit 1042, it is shaped into a cluster that can pass through the accelerator 105. Adjacent focusing units will shape the beam from two directions respectively, and finally form a radially compressed ion beam, which is beneficial to the subsequent acceleration process. The ion beam passing through the accelerator 105 is accelerated and finally reaches the target energy.

[0003] like Figure 3As shown, the size of the slits for ions to pass through on the first ground electrode 131, the first accelerating electrode 132 and the second ground electrode 133 in the bunching assembly 103 (i.e., the central through holes of the first ground electrode 131, the first accelerating electrode 132 and the second ground electrode 133) is much larger in height than in width. This design makes the voltage in the axial direction higher and more ions pass through. However, the design of the slit shape causes the slits of the first accelerating electrode 132 and the second ground electrode 133 to be higher than the slit of the first ground electrode 131, making the electric field present a "trumpet shape". After passing through the bunching assembly 103, the ion beam 200a will diverge radially and become a divergent ion beam 200b. Since the high-energy ion implanter is suitable for a variety of ions, the middle number of the mass-to-charge ratio of commonly used ions is generally used for design. After most commonly used ions pass through the bunching assembly 103 with appropriate voltage, the radial divergence is controlled within a certain range, and most ions can pass through the subsequent first focusing unit 1041. However, for some ions with a relatively small mass-to-charge ratio, such as H + 、He + , B 2+ The required focusing voltage is also larger, so the radial electric field component is also larger, and the radial diffusion of the ion beam is very serious. Figure 3 As shown, the radius of the central hole of the focusing assembly 104 is the same as that of the central hole of the accelerator 105, and the height of the ion beam 200b has exceeded the central holes of the third ground electrode 141 and the fourth ground electrode 143 in the first focusing unit 1041, resulting in serious ion loss. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention innovatively provides a variable-diameter focusing assembly, a radio frequency acceleration section and an ion implanter, wherein the radius of the ion beam channel on the focusing unit in the focusing assembly is enlarged and the radius of the ion beam channel on multiple focusing units is gradually reduced along the direction of movement of the ion beam flow, and the radius of the ion beam channel on the last focusing unit is greater than or equal to the radius of the ion beam channel on the accelerator. The ion beam that is radially over-divergent due to the bunching assembly can be shaped, thereby reducing the loss caused by ion beam diffusion and improving the transmission efficiency of the ion beam. The ion beam can be applied to ions of all mass-to-charge ratios.

[0005] To achieve the above-mentioned technical objectives, the first aspect of the present invention discloses a variable diameter focusing assembly, comprising a plurality of focusing units arranged along the direction of movement of an ion beam, wherein the plurality of focusing units are arranged with alternating polarity, and the ion beam channel radius on the plurality of focusing units gradually decreases along the direction of movement of the ion beam, and the ion beam channel radius on the rearmost focusing unit is greater than or equal to the ion beam channel radius on the accelerator downstream of the variable diameter focusing assembly.

[0006] Furthermore, the radii of the ion beam channels on the multiple focusing units decrease in an arithmetic progression along the moving direction of the ion beam flow.

[0007] Furthermore, the radius of the ion beam channel on the frontmost focusing unit is twice the radius of the ion beam channel on the accelerator downstream of the variable-diameter focusing assembly.

[0008] Furthermore, the focusing unit includes a fifth ground electrode, a sixth ground electrode and a focusing lens between the fifth ground electrode and the sixth ground electrode, the radius of the ion beam channel on the fifth ground electrode and the sixth ground electrode is the same, and the radius of the ion beam channel of the focusing lens is larger than the radius of the ion beam channel on the fifth ground electrode and the sixth ground electrode.

[0009] Furthermore, the focusing lens is a quadrupole lens or a hexapole lens.

[0010] To achieve the above technical objectives, the second aspect of the present invention discloses a radio frequency acceleration section, comprising a beam-forming component, the variable diameter focusing component described in the first aspect, and an accelerator.

[0011] The bunching assembly is used to bunch the ion beam into a bunched beam.

[0012] The variable diameter focusing assembly is arranged downstream of the bunching assembly and is used to focus the bunched beam.

[0013] The accelerator is arranged downstream of the variable diameter focusing assembly and is used to accelerate the focused ion beam to a preset energy.

[0014] To achieve the above technical objectives, the third aspect of the present invention discloses an ion implanter, comprising an ion source, a mass analyzer and the radio frequency acceleration section described in the second aspect.

[0015] The ion source is used to generate an ion beam;

[0016] The mass analyzer is arranged downstream of the ion source, and is used to perform mass analysis on the ion beam generated by the ion source and screen out the ion species required for injection to obtain a purified beam;

[0017] The radio frequency acceleration section is arranged downstream of the mass analyzer, and is used to form a bunched beam, and accelerate the beam after focusing to obtain a beam with a preset energy.

[0018] The beneficial effects of the present invention are:

[0019] The variable-diameter focusing assembly of the present invention enlarges the ion beam channel radius on the focusing unit in the focusing assembly and gradually reduces the ion beam channel radius on multiple focusing units along the direction of ion beam flow movement. The ion beam channel radius on the last focusing unit is greater than or equal to the ion beam channel radius on the accelerator. The ion beam that is radially over-divergent due to the bunching assembly can be shaped, thereby reducing the loss caused by ion beam diffusion, improving the transmission efficiency of the ion beam, and is applicable to ions of all mass-to-charge ratios. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of an existing ion implanter.

[0021] Figure 2 It is a schematic diagram of the three-dimensional structure of the existing beam-forming component and focusing component.

[0022] Figure 3 The ion beam passes through Figure 2 A diagram of the diffusion after the existing bunching component is shown.

[0023] Figure 4 It is a schematic structural diagram of a variable diameter focusing assembly according to an embodiment of the present invention.

[0024] Figure 5 It is a structural schematic diagram of the radio frequency acceleration section of an embodiment of the present invention.

[0025] Figure 6 This is a simulation diagram of the trajectory of a proton particle beam passing through a bunching component and an existing focusing component before reaching the accelerator.

[0026] Figure 7 It is a simulation diagram of the trajectory of a proton particle beam before it passes through a bunching component and a focusing component of an embodiment of the present application and reaches an accelerator.

[0027] In the figure,

[0028] 101, ion source; 102, mass analyzer; 110, radio frequency acceleration section; 103, bunching assembly; 131, first ground electrode; 132, first accelerating electrode; 133, second ground electrode; 134a, first gap; 134b, second gap; 104, focusing assembly; 1041, first focusing unit; 1042, second focusing unit; 141, third ground electrode; 142, quadrupole lens; 143, fourth ground electrode; 105, accelerator; 200a, ion beam; 200b, divergent ion beam; 141', fifth ground electrode; 142', focusing lens; 143', sixth ground electrode; 1041', first focusing unit; 1042', second focusing unit; 1043', third focusing unit. DETAILED DESCRIPTION

[0029] The variable diameter focusing assembly, radio frequency acceleration section and ion implanter provided by the present invention are explained and illustrated in detail below in conjunction with the drawings in the specification.

[0030] This embodiment specifically discloses a variable diameter focusing component, such as Figure 4 As shown, it includes a plurality of focusing units arranged along the direction of movement of the ion beam, and the plurality of focusing units are arranged with alternating polarity. Through the alternating polarity arrangement of the focusing units, the ion beam can be cross-replaced in multiple directions for focusing, thereby improving the focusing effect and reducing the radial diffusion of the ion beam. In the present application, axial refers to the direction of movement of the ion beam, and radial refers to the direction perpendicular to the movement of the ion beam. The number of focusing units is selected according to the length design of the overall RF acceleration section, and is also designed according to the actual focusing effect and the mass-to-charge ratio of the ions. The more focusing units there are, the better the beam shaping effect is, but the longer the overall occupied length is. Preferably, the number of focusing units is 2 to 10, more preferably 3. The ion beam channel radius on the plurality of focusing units gradually decreases along the direction of movement of the ion beam, and the ion beam channel radius on the rearmost focusing unit is greater than or equal to the ion beam channel radius on the accelerator 105 downstream of the variable diameter focusing assembly. Preferably, the radius of the ion beam channel on the rearmost focusing unit is the same as the radius of the ion beam channel of the accelerator 105, that is, the radius of the ion beam channel on the rearmost focusing unit is the same as the radius of the ion beam channel on the focusing unit in the prior art, and no change is made, while the radius of the ion beam channel on the other focusing units except the rearmost focusing unit is appropriately enlarged. The ion beam channel on the focusing unit is formed by a through hole opened on the focusing unit, and the radius of the ion beam channel on the focusing unit is the radius of the smallest through hole in the components constituting the focusing unit. In this embodiment, the through hole on the focusing unit is set at the center of the focusing unit and is a circular hole. In this embodiment, the accelerator 105 is an accelerating electrode, and the ion beam channel on the accelerator 105 is the central through hole on the accelerating electrode.

[0031] In this embodiment, the ion beam channels on the multiple focusing units of the focusing assembly are designed to be reduced in sequence, and the multiple focusing units are arranged with alternating polarities, and the ion beam is gradually focused from multiple directions along the direction of the ion beam flow to be shaped. The frontmost focusing unit ensures that the ions in the ion beam flow after passing through the bunching assembly 103 can basically be injected into it, and the subsequent focusing units gradually focus. In addition, the expansion of the radius of the ion beam channel on the focusing unit allows the ions with a relatively small charge-to-mass ratio that have a large radial expansion after passing through the bunching assembly 103 to be injected into the focusing unit, thereby reducing the loss caused by the diffusion of the ion beam.

[0032] Optionally, the focusing unit includes a fifth ground electrode 141', a sixth ground electrode 143', and a focusing lens 142' between the fifth ground electrode 141' and the sixth ground electrode 143'. The radii of the ion beam channels on the fifth ground electrode 141' and the sixth ground electrode 143' are the same, and the radius of the ion beam channel of the focusing lens 142' is larger than the radius of the ion beam channels on the fifth ground electrode 141' and the sixth ground electrode 143'. The focusing lens plays a focusing role, and the radius of the ion beam channel of the focusing lens is larger than the radius of the ion beam channel of the fifth ground electrode 141' and the sixth ground electrode 143' to avoid blocking the ions. The ion beam channels on the fifth ground electrode 141' and the sixth ground electrode 143' refer to the central through holes on the fifth ground electrode 141' and the sixth ground electrode 143'. The radius of the ion beam channel on the focusing unit is actually the radius of the central through holes of the fifth ground electrode 141' and the sixth ground electrode 143'.

[0033] The focusing lens 142' is a quadrupole lens or a hexapole lens. The quadrupole lens is composed of four semicircular electrodes uniformly distributed in the circumference, and the electrodes facing each other are kept at a distance. The ion beam channel of the quadrupole lens refers to the central channel surrounded by the four semicircular electrodes. The radius of the ion beam channel of the quadrupole lens refers to half of the distance between the electrodes facing each other. The electrodes facing each other in one direction of the quadrupole lens focus in one direction, so the quadrupole lens has the ability to focus in two perpendicular directions in the radial direction. The polarities of multiple quadrupole lenses are cross-distributed, and they focus alternately in two perpendicular directions to improve the focusing effect. The hexapole lens is composed of six semicircular electrodes evenly distributed in the circumference, and the electrodes facing each other keep a distance. The ion beam channel of the hexapole lens refers to the central channel surrounded by the six semicircular electrodes. The ion beam channel radius of the hexapole lens refers to half of the distance between the electrodes facing each other. The circular electrodes facing each other in one direction of the hexapole lens focus in one direction, so the hexapole lens has the ability to focus in three directions. The three directions form an angle of 60° in the radial direction. The polarities of multiple hexapole lenses are cross-distributed, and they focus alternately in three directions to improve the focusing effect.

[0034] Optionally, the ion beam channel radii on multiple focusing units decrease according to an arithmetic progression along the direction of ion beam movement, and the difference transition of ion beam channel radii between adjacent focusing units is the same, so that the ion beam is gradually and evenly focused to improve the focusing effect, thereby enabling more ions to enter the next focusing unit, reducing ion losses and improving the focusing effect.

[0035] The radius of the ion beam channel on the frontmost focusing unit is twice the radius of the ion beam channel on the accelerator 105 downstream of the variable diameter focusing assembly, which can fully accommodate the ions with low mass-to-charge ratio radially diverging after passing through the bunching assembly 103, such as H + (proton), He + , B 2+Etc., almost all of the ion beam after passing through the bunching assembly 103 enters the focusing unit, reducing ion loss.

[0036] like Figure 5 As shown, the diameter of the ion beam channel on the accelerator 105 is 25.4 mm, that is, the diameter of the central through hole of the accelerator 105 is 25.4 mm, the number of focusing units is 3, which are respectively a first focusing unit 1041', a second focusing unit 1042' and a third focusing unit 1043' arranged along the moving direction of the ion beam flow, and the focusing lenses 142' of the first focusing unit 1041', the second focusing unit 1042' and the third focusing unit 1043' are all quadrupole lenses, and the diameter of the ion beam channel of the first focusing unit 1041' is 50.8 mm (that is, the diameter of the first focusing unit 1041' is 50.8 mm). The diameter of the central through hole of the fifth ground electrode 141' and the sixth ground electrode 143' of the element 1041' is 50.8 mm, the diameter of the ion beam channel on the second focusing unit 1042' is 38.1 mm (i.e., the diameter of the central through hole of the fifth ground electrode 141' and the sixth ground electrode 143' of the second focusing unit 1042' is 38.1 mm), and the diameter of the ion beam channel on the third focusing unit 1043' is 25.4 mm (i.e., the diameter of the central through hole of the fifth ground electrode 141' and the sixth ground electrode 143' of the third focusing unit 1043' is 25.4 mm). The ion H with the smallest mass-to-charge ratio + After the formed ion beam 200a passes through the first ground electrode 131 and the first accelerating electrode 132 (bunching electrode) of the bunching assembly 103, it begins to expand in the y direction. After passing through the second ground electrode 133, a parallel ion beam 200b is formed, and the ion beam aspect ratio is »1 (the y-direction length / x-direction length is much greater than 1). By adjusting the appropriate focusing voltage, after the ion beam passes through the first focusing unit 1041', the ion beam is compressed in the y direction and expanded in the x direction, and the aspect ratio is compressed to <1; after passing through the second focusing unit 1042', the ion beam is compressed in the x direction and expanded in the y direction, and the aspect ratio is >1; after passing through the third focusing unit 1043', the ion beam is compressed in the y direction and expanded in the x direction, and the aspect ratio is ≈1. In this way, the shaped ion beam can all pass through the accelerator 105, and the radial loss is greatly reduced.

[0037] By adjusting the distance between the bunching assembly 103 and the focusing assembly, the distance between the focusing units in the focusing assembly, the distance between the focusing lens 142' and the fifth ground electrode 141', the distance between the focusing lens 142' and the sixth ground electrode 143', and the focusing voltage, it can be applicable to ions with other charge-to-mass ratios. For ions with other charge-to-mass ratios, the variable diameter focusing assembly of the present application can also perform effective shaping, greatly reduce radial losses, and enable almost all ions to finally enter the accelerator 105 and be accelerated to a preset energy.

[0038] Figure 6This is a simulation diagram of the trajectory of the proton particle beam before it passes through the bunching component and the existing focusing component and reaches the accelerator. Figure 6 The adopted focusing assembly includes three focusing units: a first focusing unit, a second focusing unit and a third focusing unit. The diameter of the central through hole of the first focusing unit, the second focusing unit and the third focusing unit is 25.4 mm.

[0039] Figure 7 This is a simulation diagram of the trajectory of a proton particle beam before it passes through a bunching component and a focusing component of an embodiment of the present application and reaches an accelerator. Figure 5 The focusing assembly shown, ie the focusing assembly, has three focusing units.

[0040] Figure 6 and Figure 7 The simulation software used is matlab, and the parameters are set as follows: ion beam release characteristics: 18,000 particles in one cycle, randomly distributed in the initial position plane, parallel beam; particle beam energy is 80 keV; the voltage of the first accelerating electrode 132 of the bunching component 103 is 34.95 kV; the voltages of the quadrupole lenses 142 of the first focusing unit, the second focusing unit, and the third focusing unit of the existing focusing component are 5 kV, 6 kV, and 5 kV, respectively; Figure 5 The voltages of the focusing lens 142' of the first focusing unit 1041', the second focusing unit 1042' and the third focusing unit 1043' in the embodiment of the present application are 10kV, 9kV and 5kV respectively. It should be noted that the voltages of the quadrupole lens 142 and the focusing lens 142' are determined according to the formula: electric field strength = 2*V / a, where V refers to voltage and a refers to the distance between the electrodes of a single quadrupole lens that are opposite to each other; since the radius of the central through hole in the embodiment of the present application is larger than that in the prior art, the voltage V of the focusing lens 142 must be increased accordingly, otherwise the electric field strength is insufficient, and the above voltage setting is used to ensure Figure 6 and Figure 7 The electric field strength is the same.

[0041] Figure 6 The left side is a three-dimensional view, and the right side is a cross-sectional view. The green circle in the left three-dimensional view is the position of the central through hole of the third ground electrode 141 in the three focusing units of the focusing assembly, and the red circle in the right cross-sectional view is the position of the central through hole on the front end surface of the accelerator; Figure 7 The left side is a three-dimensional view, and the right side is a cross-sectional view. The green circle in the left three-dimensional view is the position of the central through hole of the fifth ground electrode 141' in the three focusing units of the focusing assembly, and the red circle in the right cross-sectional view is the position of the central through hole on the front end surface of the accelerator. Figure 61-5 are different stages of the proton beam movement process, 1 is the proton beam head beginning to enter the first focusing unit (the entrance of the third ground electrode 141), 2 is the proton beam head leaving the first focusing unit, 3 is the proton beam head beginning to enter the second focusing unit, 4 is the proton beam head beginning to enter the third focusing unit, and 5 is the proton beam head entering the accelerator. Figure 7 1-5 are different stages of the proton beam movement process, 1 is the proton beam head entering the first focusing unit 1041', 2 is the proton beam head starting to enter the second focusing unit 1042', 3 is the proton beam head leaving the second focusing unit 1042', 4 is the proton beam head starting to enter the third focusing unit 1043', and 5 is the beam head entering the accelerator 105. Figure 6 It can be seen that the proton particle beam undergoes radial expansion after passing through the first accelerating electrode 132. When reaching the entrance of the third ground electrode 141 of the first focusing unit 1041, the portion exceeding the radius of the central through hole is blocked and cannot enter the subsequent accelerator 105. The overall passing rate is 78.84% (14192 / 18000). Figure 7 It can be seen that the proton particle beam expands after passing through the first accelerating electrode 132, but the central through hole of the first focusing unit 1041' can completely accommodate the particle beam and compress it in the y direction, so that it passes through the second focusing unit 1042' and the third focusing unit 1043' and is radially compressed. Finally, almost all particles can enter the accelerator 105, and the overall pass rate is 99.36% (178857 / 18000). Compared with the prior art, the ion pass rate is greatly improved and the loss caused by ion beam diffusion is reduced.

[0042] The present application also discloses a radio frequency acceleration section, such as Figure 5 As shown, it includes a beam-forming component 103, a variable-diameter focusing component and an accelerator 105 as described in the above embodiment,

[0043] The bunching assembly 103 is used to bunch the ion beam into a bunched beam;

[0044] The variable diameter focusing assembly is arranged downstream of the bunching assembly 103, and is used to focus the bunched beam, reduce the radial loss of ions, and is applicable to ions of all charge-to-mass ratios;

[0045] The accelerator 105 is disposed downstream of the variable diameter focusing assembly and is used to accelerate the focused ion beam to a preset energy.

[0046] The present application also discloses an ion implanter, comprising an ion source, a mass analyzer and a radio frequency acceleration section of the above embodiment.

[0047] An ion source is used to generate an ion beam;

[0048] The mass analyzer is arranged downstream of the ion source, and is used to perform mass analysis on the ion beam generated by the ion source and screen out the ion species required for injection to obtain a purified beam;

[0049] The radio frequency acceleration section is arranged downstream of the mass analyzer and is used to form a bunched beam and accelerate it after focusing to obtain a beam with a preset energy.

[0050] By gradually reducing the radius of the ion beam channel of the focusing assembly of the present application, the ion implanter can be applied to ions of all mass-to-charge ratios, reduce the loss caused by radial diffusion of ions, and improve the ion transmission efficiency.

[0051] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, 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.

[0052] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the description of this specification, the description with reference to the terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any at least one embodiment or example. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0054] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying 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 at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and simple improvements made to the essential contents of the present invention should be included in the protection scope of the present invention.

Claims

1. A variable diameter focusing assembly, characterized in that: The invention comprises a plurality of focusing units arranged along the moving direction of the ion beam, wherein the plurality of focusing units are arranged with alternating polarity, the ion beam channel radius on the plurality of focusing units gradually decreases along the moving direction of the ion beam, the ion beam channel radius on the rearmost focusing unit is greater than or equal to the ion beam channel radius on the accelerator downstream of the variable-diameter focusing component; the ion beam channel radius on the plurality of focusing units decreases according to an arithmetic progression along the moving direction of the ion beam; the ion beam channel radius on the frontmost focusing unit is twice the ion beam channel radius on the accelerator downstream of the variable-diameter focusing component.

2. The variable diameter focusing assembly according to claim 1, characterized in that: The focusing unit includes a fifth ground electrode, a sixth ground electrode and a focusing lens between the fifth ground electrode and the sixth ground electrode. The radius of the ion beam channel on the fifth ground electrode and the sixth ground electrode is the same, and the radius of the ion beam channel of the focusing lens is larger than the radius of the ion beam channel on the fifth ground electrode and the sixth ground electrode.

3. The variable diameter focusing assembly according to claim 2, characterized in that: The focusing lens is a quadrupole lens or a hexapole lens.

4. A radio frequency acceleration section, characterized in that: It comprises a beam-forming component, a variable diameter focusing component as claimed in any one of claims 1 to 3, and an accelerator, The bunching assembly is used to bunch the ion beam into a bunched beam. The variable diameter focusing assembly is arranged downstream of the bunching assembly and is used to focus the bunched beam. The accelerator is arranged downstream of the variable diameter focusing assembly and is used to accelerate the focused ion beam to a preset energy.

5. An ion implanter, characterized in that: comprising an ion source, a mass analyzer and the radio frequency acceleration section as claimed in claim 4, The ion source is used to generate an ion beam; The mass analyzer is arranged downstream of the ion source, and is used to perform mass analysis on the ion beam generated by the ion source and screen out the ion species required for injection to obtain a purified beam; The radio frequency acceleration section is arranged downstream of the mass analyzer, and is used to form a bunched beam, and accelerate the beam after focusing to obtain a beam with a preset energy.

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