Multi-beamlet charged particle beam drawing apparatus

Abstract

The present embodiment provides a multi-charged particle beam drawing apparatus that suppresses a beam position shift on a sample surface. The charged particle beam drawing apparatus of the present embodiment is a multi-charged particle beam drawing apparatus including: a blanking aperture array substrate provided with a plurality of blankers that perform blanking deflection of a plurality of charged particle beams that constitute a plurality of beams; and a first shielding member disposed on a downstream side of the blanking aperture array substrate in a traveling direction of the plurality of beams, having a cylindrical portion through which the plurality of beams pass inside, and being composed of a high magnetic permeability material.

Description

[0001] Related applications

[0002] This application enjoys priority to Japanese Patent Application No. 2021-098831 (filed on June 14, 2021) and Japanese Patent Application No. 2022-070232 (filed on April 21, 2022). This application incorporates all contents of the basic applications by reference to them. Technical Field

[0003] This invention relates to a multi-charged particle beam mapping apparatus. Background Technology

[0004] With the increasing integration of LSI (Light Silicon Integrated Systems), the required linewidths for semiconductor devices are becoming increasingly smaller each year. To form the desired circuit patterns on semiconductor devices, the following method is used: a reduction projection exposure device is used to reduce and transfer a high-precision original pattern (mask, or especially the original pattern used in steppers and scanners, also called a reticle) formed on quartz onto a wafer. This high-precision original pattern is then drawn using an electron beam lithography device, employing a technique known as electron beam lithography.

[0005] Compared to using a single electron beam, a multi-beam drawing apparatus can irradiate more beams at once, thus significantly improving productivity. In a multi-beam drawing apparatus utilizing a blanking aperture array substrate, for example, an electron beam emitted from an electron gun is passed through a shaped aperture array with multiple openings to form multiple beams (multiple electron beams). The multiple beams pass through corresponding blankers within the blanking aperture array substrate. The blanking aperture array substrate has electrode pairs for individually deflecting the beams and openings for the beams to pass through. One electrode pair (blanker) is fixed to ground potential, and the other is switched between ground potential and other potentials, thereby individually blanking and deflecting the passing electron beams. The electron beams deflected by the blankers are shielded, and the undeflected electron beams irradiate the sample.

[0006] In conventional multi-beam mapping devices, the beam path is sometimes slightly bent due to the influence of the magnetic field generated by the current flowing through the blanking aperture array substrate, causing the beam irradiation position on the sample surface to deviate and the mapping accuracy to deteriorate. Summary of the Invention

[0007] This embodiment provides a multi-charged particle beam mapping device for suppressing beam position deviation on the sample surface.

[0008] One aspect of the present invention provides a multi-charged particle beam mapping apparatus comprising: a blanking aperture array substrate having a plurality of blanking elements that perform blanking deflection on each of the plurality of charged particle beams constituting a multi-beam; and a first shielding member disposed downstream of the blanking aperture array substrate in the direction of travel of the multi-beam, having a cylindrical portion through which the multi-beam passes, and being made of a high permeability material. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a multi-charged particle beam mapping apparatus according to an embodiment of the present invention.

[0010] Figure 2 This is a top view of a substrate with a shaped aperture array.

[0011] Figure 3A This is a 3D view of the first shielding component. Figure 3B This is a longitudinal section view of the first shielding component.

[0012] Figure 4 This is a 3D view of the second shielding component.

[0013] Figure 5 This is a 3D view of the third shielding component.

[0014] Figure 6 This is a schematic diagram of magnetic field absorption based on shielding components.

[0015] Figure 7 This is a 3D view of the fourth shielding component.

[0016] Figure 8 It is a graph representing the simulation results of the cumulative deflection.

[0017] Explanation of reference numerals in the attached figures

[0018] 10-Aperture Array Substrate

[0019] 20 blanking aperture array substrate

[0020] 30 First shielding component

[0021] 40 Second shielding component

[0022] 50 Third shielding component

[0023] 100 Drawing device Detailed Implementation

[0024] In charged particle beam mapping apparatuses, shielding is often arranged around the lens barrel to block external magnetic fields. However, in multi-beam mapping apparatuses, it is necessary to shield the magnetic field from inside the lens barrel, which is essential for the control circuitry of the blanking aperture array substrate during multi-beam mapping operations. Therefore, simply covering the area through which the beam passes is insufficient; it is required to ensure the area through which the beam passes, and to have a gap for connecting the electrical wiring used to operate the blanking aperture array substrate between the blanking aperture array substrate and the lens barrel wall connector. Ensuring the area through which the beam passes and the gap for wiring contradicts the general magnetic shielding design principle of covering as close to the gap as possible. What is needed is not simply to shield as much as possible, but to consider the impact on the beam when determining the shielding configuration and arrangement. The specific configuration is described below based on the accompanying drawings.

[0025] In the following embodiments, an electron beam configuration will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam; it may also be an ion beam, etc.

[0026] Figure 1 This is a schematic diagram of the apparatus used in the embodiment. Figure 1 The depiction apparatus 100 shown is an example of a multi-charged particle beam depiction apparatus. The depiction apparatus 100 includes an electron tube 102 and a depiction chamber 103. Inside the electron tube 102 are arranged an electron gun 111, an illumination lens 112, a forming aperture array substrate 10, a blanking aperture array substrate 20, a shielding component S, a reducing lens 115, a limiting aperture component 116, an objective lens 117, a deflector 118, and an overall blanking device 119.

[0027] The blanking aperture array substrate 20 includes a blanking aperture array chip (BAA chip) and a mounting substrate for mounting the BAA chip. The BAA chip is equipped with a blanker for blanking each beam of a multi-beam array. For example, the BAA chip and the mounting substrate are connected by wire bonding. The mounting substrate includes a relay circuit for data transmission and a control circuit containing circuit elements for power supply stabilization. A shielding member S shields the magnetic field caused by the current flowing through the control circuit.

[0028] The shielding component S has at least a first shielding component 30. The shielding component S may also have two or more shielding components. Figure 1The diagram also shows a configuration including a second shielding member 40 and a third shielding member 50. The first shielding member 30, the second shielding member 40, and the third shielding member 50, while avoiding electronic components mounted on the mounting substrate of the blanking aperture array substrate 20, have metal fixing members in contact with the surface and back of the mounting substrate of the blanking aperture array substrate 20, and are secured by screws passing through fixing holes formed in the mounting substrate and the metal fixing members. The shielding member S suppresses the influence of the magnetic field generated by the current flowing through the blanking aperture array substrate 20 on the beam trajectory, and is made of a high permeability material capable of absorbing magnetic flux. High permeability materials can be alloys of iron, nickel, cobalt, etc., with a relative permeability of 1 or higher; permalloy is an example of such a material.

[0029] An XY stage 105 is arranged inside the drawing chamber 103. A sample 101, such as a mask, which will be the substrate to be drawn during the drawing process, is arranged on the XY stage 105. The sample 101 includes an exposure mask used in manufacturing a semiconductor device or a semiconductor substrate (silicon wafer) used in manufacturing a semiconductor device. In addition, the sample 101 includes a mask blank coated with photoresist that has not yet been drawn.

[0030] like Figure 2 As shown, openings 12, arranged in m columns × n columns (m, n≥2), are formed on the shaped aperture array substrate 10 at a predetermined spacing. Each opening 12 is formed of a rectangle of the same size and shape. The shape of the openings 12 can also be circular. A portion of the electron beam B passes through these multiple openings 12, thereby forming a multi-beam MB.

[0031] A blanking aperture array substrate 20 is disposed below a shaped aperture array substrate 10. Through-holes 22 are formed on the BAA chip of the blanking aperture array substrate 20, matching the arrangement positions of each opening 12 on the shaped aperture array substrate 10. Near each through-hole 22 on the lower (or upper) surface side of the BAA chip, a blanking device consisting of a pair of blanking electrodes (not shown) is disposed. One blanking electrode is fixed to ground potential, while the other switches between ground potential and another potential.

[0032] By using the control circuit provided on the mounting substrate, a desired potential can be applied to each blanking electrode.

[0033] The electron beams passing through each aperture 22 are deflected independently according to the voltage applied to the blanking device. In this way, multiple blanking devices perform blanking deflection of the individual beams corresponding to the multiple beams MB passing through the multiple openings 12 of the shaped aperture array substrate 10.

[0034] A first shielding member 30 is disposed below the blanking aperture array substrate 20 (downstream of the beam travel direction).

[0035] like Figure 3A , Figure 3B As shown, the first shielding member 30 has a first cylindrical portion 31. Furthermore, a second cylindrical portion 32 with a diameter larger than the first cylindrical portion 31 can be connected via a connecting portion 33. The first cylindrical portion 31 is located on the upper side of the blanking aperture array substrate 20, and the second cylindrical portion 32 is located on the lower side. The first cylindrical portion 31 and the second cylindrical portion 32 are coaxial. The axial directions of the first cylindrical portion 31 and the second cylindrical portion 32 are parallel to the travel direction of the multi-beam MB.

[0036] A beam path exists at the center of the first shielding component 30. To prevent magnetic fields leaking from the blanking aperture array substrate 20 from entering the beam path, it is preferable to have a cylindrical shape with a certain length.

[0037] The connecting portion 33 connects the lower edge of the first cylindrical portion 31 to the upper edge of the second cylindrical portion 32, and reduces the diameter of the first shielding member 30. Figure 3A , Figure 3B In the example shown, the connecting portion 33 is an annular shape extending in a direction perpendicular to the side circumferential surface of the first cylindrical portion 31 and the side circumferential surface of the second cylindrical portion 32, but it can also be an inclined surface that gradually narrows towards the upper side.

[0038] When the overall shape (beam shape) of the multi-beam MB is, for example, a square and the length of one side is set to D0, the inner diameter D1 of the first cylindrical portion 31 is preferably more than √2 times and less than 5 times D0, so as to be larger than the circumcircle of the beam shape.

[0039] The height H1 of the first cylindrical portion 31 of the first shielding component 30 is preferably set to be greater than or equal to the inner diameter D1, for example, it can be 3 or 4 times.

[0040] The thickness T1 of the first cylindrical portion 31, the second cylindrical portion 32, and the connecting portion 33 is not particularly limited, but it is sufficient to shield the magnetic field.

[0041] For example, preferably, the thickness T1 is 0.1 mm or more and 5 mm or less, the inner diameter D1 of the first cylindrical portion 31 is 18 mm or more and 70 mm or less, the inner diameter D2 of the second cylindrical portion 32 is larger than 18 mm and less than 100 mm, the height H1 of the first cylindrical portion 31 is 0.3 mm or more and 30 mm or less, and the height H2 of the second cylindrical portion 32 is 1 mm or more and 100 mm or less.

[0042] A second shielding member 40 may also be disposed between the shaped aperture array substrate 10 and the blanking aperture array substrate 20. Furthermore, a third shielding member 50 may also be disposed between the blanking aperture array substrate 20 and the first shielding member 30.

[0043] like Figure 4 As shown, the second shielding member 40 has an opening 41 for multiple beams MB to pass through in the center of the rectangular plate in top view. The diameter D3 of the opening 41 is the same as the inner diameter D1 of the first cylindrical portion 31 of the first shielding member 30.

[0044] The lengths L1 and L2 of the sides of the second shielding component 40 are not particularly limited, as long as they do not interfere with the components inside the lens barrel. The thickness T2 of the second shielding component 40 is the same as the thickness T1 of the first shielding component 30.

[0045] For example, the preferred thicknesses are: T2 is 0.1 mm to 5 mm, lengths L1 and L2 are 23 mm to 140 mm, and inner diameter D3 is 22.6 mm to 50 mm.

[0046] like Figure 5 As shown, the third shielding member 50 is formed in an annular shape with an opening 51 for multiple beams MB to pass through in the center of a circular plate. The inner diameter D4 of the opening 51 is the same as the inner diameter D1 of the first cylindrical portion 31 of the first shielding member 30.

[0047] The outer diameter D5 of the third shielding member 50 is not particularly limited, but it is desirable, for example, that its length extends to the end of the power plane of the blanking aperture array substrate 20. Shielding is achieved to prevent the magnetic field from escaping between the blanking aperture array substrate 20 and the first shielding member 30. The thickness T3 of the third shielding member 50 is the same as the thickness T1 of the first shielding member 30.

[0048] For example, preferably, the thickness T3 is 0.1 mm to 5 mm, the inner diameter D4 is 23 mm to 50 mm, and the outer diameter D5 is 24 mm to 100 mm.

[0049] In the case where this shielding component S is provided Figure 1 In the depiction apparatus 100 shown, the electron beam B emitted from the electron gun 111 (release section) passes approximately perpendicularly through the reducing lens 115 via the illumination lens 112, illuminating the entire shaped aperture array substrate 10 while reducing the overall shape of the beam. However, the reducing lens 115 may also be provided on the downstream side of the blanking aperture array substrate 20.

[0050] Electron beam 130 passes through multiple openings 12 of the shaped aperture array substrate 10, thereby forming a multi-beam MB containing multiple electron beams. The multi-beam MB passes through openings 41 of the second shielding member 40 and passes between corresponding blankers of the blanking aperture array substrate 20.

[0051] The multi-beam MB passing through the blanking aperture array substrate 20 passes through the opening 51 of the third shielding member 50, and then passes through the inside of the first cylindrical portion 31 and the second cylindrical portion 32 of the first shielding member 30.

[0052] The multi-beam MB, passing through the first shielding member 30, advances towards the opening at the center of the limiting aperture member 116 as the overall shape of the beam shrinks, via the overall blanking member 119 used to disconnect the beams. Here, the electron beams deflected by the blanking member of the blanking aperture array substrate 20 are deviated from the opening at the center of the limiting aperture member 116 and are blocked by the limiting aperture member 116. On the other hand, the electron beams not deflected by the blanking member pass through the opening at the center of the limiting aperture member 116. Blanking control is performed by turning the blanking member and the overall blanking member on / off, controlling the on / off state of the beams.

[0053] Thus, the aperture limiting component 116 blocks each beam that has been deflected into a beam-off state by multiple blanking devices. Then, a single-shot beam is formed using the beam that has passed through the aperture limiting component 116 from the beam being turned on to the beam being turned off.

[0054] The multiple beams passing through the aperture limiting component 116 are focused by the objective lens 117 to form a pattern image with the desired reduction ratio. The multiple beams are collectively deflected in the same direction by the deflector 118, irradiating each irradiation position on the sample 101. As the XY stage 105 moves continuously, the deflector 118 controls the irradiation position of the beams to follow the movement of the XY stage 105.

[0055] Ideally, the multiple beams irradiated in a single irradiation should be arranged with a spacing obtained by multiplying the arrangement spacing of the multiple openings 12 of the shaped aperture array substrate 10 by the aforementioned desired reduction rate. The drawing apparatus 100 performs a drawing operation by grating scanning or the like, which continuously irradiates the emitted beams in sequence. When drawing the desired pattern, unwanted beams are controlled to be disconnected by blanking control.

[0056] A magnetic field is generated by the current flowing through the control circuit of the blanking aperture array substrate 20, which performs blanking control. The generated magnetic field is as follows: Figure 6 As indicated by the arrows, the first shielding member 30, the second shielding member 40, and the third shielding member 50, which are positioned near the blanking aperture array substrate 20, absorb the magnetic field and release it from the ends. Therefore, the magnetic field can escape outside the trajectory of the multiple beams. Furthermore, although the beams are slightly deflected due to the release of the magnetic field from the inner diameter portion of each shielding member, the effect is minor because the cumulative deflection on the surface of the sample 101 is minimized—in other words, the experimental results and substrate model are created and designed based on simulation results within a range that allows the beam irradiation position on the surface of the sample 101 to correspond using correction techniques.

[0057] In addition, although a magnetic field can also be generated from the reducing lens 115, the magnetic field is absorbed by the second shielding member 40 disposed above the blanking aperture array substrate 20 and released outside the trajectory of the multi-beam.

[0058] Thus, in this embodiment, by providing the shielding component S to block the magnetic field, the magnetic field can escape outside the multi-beam trajectory, thereby preventing the magnetic field from intruding into the multi-beam trajectory and affecting it. This prevents the beam trajectory from bending and the beam irradiation position on the sample surface from shifting, achieving high-precision mapping.

[0059] Alternatively, a further configuration can be made between the blanking aperture array substrate 20 and the third shielding component 50. Figure 7 The fourth shielding component 60 is shown in an annular shape. The fourth shielding component 60 is made of a high magnetic permeability material, and its inner diameter D6 is the same as the inner diameter D1 of the first cylindrical portion 31 of the first shielding component 30, and its thickness T4 is the same as the thickness T1 of the first shielding component 30.

[0060] In the above embodiments, a rectangular plate with a circular opening is used for the second shielding member 40, and a circular plate with a circular opening is used for the third shielding member 50. However, the shape of the plate is not limited to rectangle or circle; it can also be a triangle, a polygon with pentagons or more, or any shape that does not interfere with the components inside the lens barrel. A circular plate with a circular opening can also be used for the second shielding member 40. In this case, the thickness, outer diameter, and inner diameter of the second shielding member 40 can be set to the same degree as those of the third shielding member 50.

[0061] In the above embodiment, a first shielding member 30 formed by connecting the first cylindrical portion 31 and the second cylindrical portion 32 is described. However, if it is configured to be sufficiently close to the blanking aperture array substrate 20, it may also be provided as a cylindrical shape with the same diameter.

[0062] In the apparatus described in the above embodiment, the overall blanking member 119 deflects the multi-beam as a whole, therefore it needs to be positioned above the limiting aperture member 116 at a certain distance from it. On the other hand, the first shielding member 30 needs to have a certain length so that the magnetic field does not intrude into the trajectory of the multi-beam. In order to meet the necessary conditions of both the position of the overall blanking member 119 and the length of the first shielding member 30, given the size limitations of the electron microscope tube 102, in this embodiment, the first shielding member 30 is configured such that a first cylindrical portion 31 is connected to a second cylindrical portion 32 with an inner diameter larger than that of the first cylindrical portion 31, and the overall blanking member 119 is positioned inside the second cylindrical portion 32.

[0063] Alternatively, high-permeability materials can be used to connect the shielding components to each other. In this case, the connection can also be achieved through connecting components.

[0064] In order to reduce the influence of aberrations and distortions on the beam, it is preferable to make the shape of the opening through which the beam passes circular in each shielding component.

[0065] Figure 8 The simulation results of the cumulative deflection of the beam with the first shielding member 30 and the third shielding member 50 provided are shown. In the simulation, Femtet (manufactured by Murata Software Co., Ltd.) was used as the analysis software to model the current paths of each power supply layer based on the circuit layout of the blanking aperture array substrate 20 (the blanking aperture array chip and its mounting substrate). In addition, the reducing lens 115, which can absorb the magnetic field from the control circuit of the blanking aperture array substrate, was also modeled, simplifying the internal structure of the actual electron tube 102.

[0066] Then, the current flowing through the blanking aperture array substrate 20 is measured using an actual drawing device, and the current density distribution is calculated using the measured current value to determine the cumulative deflection.

[0067] Figure 8 The vertical axis of the graph shows the cumulative deflection, and the horizontal axis shows the position in the height direction (Z direction). Z = 0 corresponds to the position of the blanking aperture array substrate 20. According to... Figure 8 The simulation results show that the cumulative deflection is suppressed to a very small extent.

[0068] Furthermore, the present invention is not limited to the embodiments described above. During implementation, the constituent elements can be modified and modified to create a more specific embodiment without departing from its spirit. Additionally, various inventions can be formed through appropriate combinations of the multiple constituent elements disclosed in the above embodiments. For example, several constituent elements may be deleted from all the constituent elements shown in the embodiments. Moreover, constituent elements from different embodiments may be appropriately combined.

Claims

1. A multi-charged particle beam drawing apparatus comprising: a blanking aperture array substrate provided with a plurality of blankers that perform blanking deflection of a plurality of charged particle beams that constitute a plurality of beams, respectively; and a first shielding member disposed on a downstream side of the blanking aperture array substrate in a traveling direction of the plurality of beams, having a cylindrical portion through which the plurality of beams as a whole pass inside, and being composed of a high magnetic permeability material, the first shielding member shielding a magnetic field caused by a current flowing through the blanking aperture array substrate, the multi-charged particle beam drawing apparatus further comprising a third shielding member that is a flat plate, is disposed between the blanking aperture array substrate and the first shielding member, is formed with a circular opening through which the plurality of beams pass, and is composed of a high magnetic permeability material.

2. The multi-charged particle beam drawing apparatus according to claim 1, wherein the first shielding member is directly connected to another shielding member, or is connected via a connecting member composed of a high magnetic permeability material.

3. The multi-charged particle beam drawing apparatus according to claim 1, further comprising a second shielding member that is a flat plate, is disposed on an upstream side of the blanking aperture array substrate in the traveling direction of the plurality of beams, is formed with a circular opening through which the plurality of beams pass, and is composed of a high magnetic permeability material.

4. The multi-charged particle beam drawing apparatus according to claim 3, wherein the second shielding member is formed with the circular opening in a central portion of the flat plate viewed in a top view of a rectangle, a length of one side of the rectangle is 23 mm or more and 140 mm or less, and a diameter of the circular opening is 22.6 mm or more and 50 mm or less.

5. The multi-charged particle beam drawing apparatus according to claim 3, wherein the second shielding member is a circular ring.

6. The multi-charged particle beam drawing apparatus according to claim 5, wherein a thickness of the second shielding member is 0.1 mm or more and 5 mm or less, an inner diameter is 23 mm or more and 50 mm or less, and an outer diameter is 24 mm or more and 100 mm or less.

7. The multi-charged particle beam drawing apparatus according to claim 3, further comprising a shaped aperture array substrate that includes a plurality of openings through which a portion of a charged particle beam passes to form the plurality of beams, respectively, the second shielding member being disposed between the shaped aperture array substrate and the blanking aperture array substrate.

8. The multi-charged particle beam drawing apparatus according to claim 1, wherein the third shielding member is a circular ring.

9. The multi-charged particle beam drawing apparatus according to claim 8, wherein a thickness of the third shielding member is 0.1 mm or more and 5 mm or less, an inner diameter is 23 mm or more and 50 mm or less, and an outer diameter is 24 mm or more and 100 mm or less.

10. The multi-charged particle beam drawing apparatus according to claim 1, further comprising a fourth shielding member that is a ring, is disposed between the blanking aperture array substrate and the third shielding member, and is composed of a high magnetic permeability material.

11. The multi-charged particle beam drawing apparatus according to claim 1, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The first shielding member has a first cylindrical portion and a second cylindrical portion having an inner diameter larger than the first cylindrical portion, A lower edge portion of the first cylindrical portion is connected to an upper edge portion of the second cylindrical portion.

12. The multi-charged particle beam drawing apparatus according to claim 11, The thickness of the first shielding member is 0.1 mm or more and 5 mm or less, the inner diameter of the first cylindrical portion is 18 mm or more and 70 mm or less, the height of the first cylindrical portion is 0.3 mm or more and 30 mm or less, and the height of the second cylindrical portion is 1 mm or more and 100 mm or less.

13. The multi-charged particle beam drawing apparatus according to claim 1, The first shielding member is composed of an alloy containing iron, nickel, or cobalt having a relative magnetic permeability of 1 or more.

14. The multi-charged particle beam drawing apparatus according to claim 13, The first shielding member is composed of a permalloy.

15. The multi-charged particle beam drawing apparatus according to claim 3, further comprising: a fourth shielding member of a ring shape disposed between the blanking aperture array substrate and the third shielding member, composed of a high magnetic permeability material. ​

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