Multi-charged particle beam lithography system

Abstract

To suppress beam position deviation on a sample surface.SOLUTION: A multi charged particle beam drawing apparatus comprises: a blanking aperture array substrate on which a plurality of blankers for performing blanking deflection on respective charged particle beams constituting a multi beam are provided; and a first shield member that is disposed on the downstream side in a direction of travel of the multi beam of the blanking aperture array substrate, has a cylindrical part inside which the multi beam passes, and is made from high permeability material. The first shield member may be coupled to another shield member directly or via a coupling member made from high permeability material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multi-charged particle beam writing apparatus. [Background technology]

[0002] As LSIs become more highly integrated, the circuit line width required for semiconductor devices is becoming finer every year. To form the desired circuit pattern on a semiconductor device, a method is adopted in which a high-precision original pattern (called a mask, or a reticle, especially when used in steppers and scanners) formed on quartz is reduced and transferred onto a wafer using a reduction projection exposure system. The high-precision original pattern is drawn using an electron beam drawing system, using so-called electron beam lithography technology.

[0003] A multi-beam lithography system can irradiate many beams at once compared to lithography using a single electron beam, thereby significantly improving throughput. In a multi-beam lithography system using a blanking aperture array substrate, for example, an electron beam emitted from a single electron gun is passed through a shaping aperture array with multiple openings to form multiple beams (multiple electron beams). The multiple beams pass through corresponding blankers on the blanking aperture array substrate. The blanking aperture array substrate has electrode pairs for individually deflecting the beams and apertures between them for beam passage. By fixing one of the electrode pairs (blankers) at ground potential and switching the other between ground and other potentials, blanking deflection of each passing electron beam is performed individually. The electron beam deflected by the blanker is shielded, while the undeflected electron beam is irradiated onto the sample.

[0004] In conventional multi-beam lithography systems, the magnetic field created by the current flowing through the blanking aperture array substrate can cause the beam trajectory to bend slightly, resulting in deviation of the beam irradiation position on the sample surface and degradation of lithography accuracy. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-079259 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-074088 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-288484 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a multi-charged particle beam drawing apparatus that suppresses beam position deviation on a sample surface. [Means for solving the problem]

[0007] A multi-charged particle beam writing apparatus according to one embodiment of the present invention comprises a blanking aperture array substrate provided with a plurality of blankers that perform blanking deflection of each of a plurality of charged particle beams that constitute a multi-beam, and a first shield member that is arranged downstream of the blanking aperture array substrate in the direction of travel of the multi-beam, has a cylindrical portion through which the multi-beam passes, and is made of a high magnetic permeability material. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress beam position deviation on the sample surface. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a multi-charged particle beam writing apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of a shaped aperture array substrate. [Figure 3] FIG. 2(a) is a perspective view of the first shielding member, and FIG. 2(b) is a vertical cross-sectional view of the first shielding member. [Figure 4] FIG. 4 is a perspective view of a second shield member. [Figure 5] FIG. 10 is a perspective view of a third shield member. [Figure 6] 10A and 10B are schematic diagrams illustrating magnetic field absorption by a shield member. [Figure 7] FIG. 10 is a perspective view of a fourth shield member. [Figure 8] 10 is a graph showing a simulation result of the cumulative deflection amount. DETAILED DESCRIPTION OF THE INVENTION

[0010] Charged particle beam lithography systems often employ shields around the column to block external magnetic fields. However, in multi-beam lithography systems, it is necessary to shield the magnetic field inside the column, especially from the control circuitry of the blanking aperture array board, which is essential for multi-beam lithography operation. Therefore, the typical magnetic shield construction method of simply covering the column with a magnetic material is insufficient. It is necessary to ensure an area through which the beam passes and to provide clearance for connecting the electrical wiring that operates the blanking aperture array board to the column wall connector. This provision of clearance for the beam passage and wiring runs counter to the general magnetic shield design guideline of covering the area as tightly as possible. Rather than simply shielding as much as possible, the shield configuration and placement must be determined taking into account the impact on the beam. A specific configuration is described below with reference to the drawings.

[0011] In the following embodiments, a configuration using an electron beam will be described as an example of a charged particle beam, but the charged particle beam is not limited to an electron beam and may be an ion beam or the like.

[0012] Fig. 1 is a schematic diagram of a drawing apparatus according to an embodiment. The drawing apparatus 100 shown in Fig. 1 is an example of a multi-charged particle beam drawing apparatus. The drawing apparatus 100 includes an electron lens barrel 102 and a drawing chamber 103. Inside the electron lens barrel 102, an electron gun 111, an illumination lens 112, a shaping aperture array substrate 10, a blanking aperture array substrate 20, a shield member S, a reduction lens 115, a limiting aperture member 116, an objective lens 117, a deflector 118, and an overall blanker 119 are arranged.

[0013] The blanking aperture array substrate 20 includes a blanking aperture array chip (BAA chip) with blankers for blanking each of the multiple beams, and a mounting substrate on which the BAA chip is mounted. For example, the BAA chip and the mounting substrate are connected by wire bonding. The mounting substrate is provided with a control circuit including a relay circuit for data transfer and circuit elements for stabilizing the power supply. The shielding member S shields against magnetic fields caused by currents flowing through this control circuit.

[0014] The shield member S includes at least a first shield member 30. The shield member S may include two or more shield members; FIG. 1 shows a configuration further including a second shield member 40 and a third shield member 50. The first shield member 30, the second shield member 40, and the third shield member 50 are fixed by contacting metal fixing components with the front and back of the mounting substrate of the blanking aperture array substrate 20 while avoiding the electronic components mounted on the mounting substrate of the blanking aperture array substrate 20, and by inserting screws into fixing holes drilled in the mounting substrate and the metal fixing components. The shield member S prevents the magnetic field generated by the current flowing through the blanking aperture array substrate 20 from affecting the beam trajectory and is made of a high-permeability material capable of absorbing magnetic flux. Examples of high-permeability materials include alloys of iron, nickel, cobalt, or the like with a relative permeability of 1 or more, such as permalloy.

[0015] An XY stage 105 is placed in the patterning chamber 103. A sample 101, such as a mask, which will be the target substrate for patterning during patterning is placed on the XY stage 105. The sample 101 includes an exposure mask used in manufacturing a semiconductor device, a semiconductor substrate (silicon wafer) on which a semiconductor device is manufactured, and the like. The sample 101 also includes a mask blank coated with resist and on which nothing is yet patterned.

[0016] As shown in Figure 2, the shaping aperture array substrate 10 has m columns x n rows (m, n ≥ 2) of apertures 12 formed at a predetermined arrangement pitch. Each aperture 12 is formed as a rectangle of the same dimensions. The shape of the apertures 12 may also be circular. Multiple beams MB are formed by portions of the electron beams B passing through each of the multiple apertures 12.

[0017] The blanking aperture array substrate 20 is provided below the shaping aperture array substrate 10. Through holes 22 are formed in the BAA chip of the blanking aperture array substrate 20 in accordance with the positions of the openings 12 of the shaping aperture array substrate 10. A blanker consisting of a pair of two blanking electrodes (not shown) is arranged on the lower (or upper) surface of the BAA chip near each through hole 22. One of the blanking electrodes is fixed at ground potential, and the other is switchable between ground potential and another potential.

[0018] A control circuit provided on the mounting board allows a desired potential to be applied to each blanking electrode.

[0019] The electron beams passing through the respective passage holes 22 are deflected independently by the voltages applied to the blankers. In this manner, the blankers perform blanking deflection on the corresponding individual beams of the multi-beam MB that have passed through the multiple openings 12 of the shaping aperture array substrate 10.

[0020] A first shield member 30 is disposed below the blanking aperture array substrate 20 (downstream in the beam traveling direction).

[0021] As shown in Figures 3(a) and 3(b), the first shield member 30 has a first cylindrical portion 31. Furthermore, a second cylindrical portion 32 having a larger diameter than the first cylindrical portion 31 may be connected via a connecting portion 33. The first cylindrical portion 31 is located on the blanking aperture array substrate 20 side (upper side), and the second cylindrical portion 32 is located on the lower side. The first cylindrical portion 31 and the second cylindrical portion 32 are located coaxially. The axial directions of the first cylindrical portion 31 and the second cylindrical portion 32 are parallel to the traveling direction of the multi-beam MB.

[0022] The beam path exists in the center of the first shield member 30. A cylindrical shape with a certain length is preferable so that the magnetic field leaking from the blanking aperture array substrate 20 does not enter the beam path.

[0023] The connecting portion 33 is a portion that connects the lower edge of the first cylindrical portion 31 and the upper edge of the second cylindrical portion 32, and reduces the diameter of the first shield member 30. In the example shown in Figures 3(a) and 3(b), the connecting portion 33 has an annular shape that extends perpendicularly to the side circumferential surfaces of the first cylindrical portion 31 and the second cylindrical portion 32, but it may also have an inclined surface that gradually reduces in diameter toward the upper side.

[0024] If the overall shape (beam shape) of the multi-beam MB is, for example, a square with the length of one side being D0, it is preferable that the inner diameter D1 of the first cylindrical portion 31 be greater than or equal to √2 and less than or equal to 5 times D0 so that it is slightly larger than the circumscribing circle of the beam shape.

[0025] The height H1 of the first cylindrical portion 31 of the first shield member 30 is preferably equal to or greater than the inner diameter D1, and may be, for example, three or four times the inner diameter D1.

[0026] The thickness T1 of the first cylindrical portion 31, the second cylindrical portion 32, and the connecting portion 33 is not particularly limited, but may be any thickness that can sufficiently shield the magnetic field.

[0027] For example, it is preferable that 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 more than 18 mm and 100 mm or less, 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.

[0028] A second shield member 40 may be disposed between the shaping aperture array substrate 10 and the blanking aperture array substrate 20. Furthermore, a third shield member 50 may be disposed between the blanking aperture array substrate 20 and the first shield member 30.

[0029] 4, the second shield member 40 has an opening 41 for passing multi-beams MB formed in the center of a rectangular flat plate in a plan view. The diameter D3 of the opening 41 is approximately the same as the inner diameter D1 of the first cylindrical portion 31 of the first shield member 30.

[0030] The lengths L1 and L2 of the sides of the second shield member 40 are not particularly limited as long as they do not interfere with components inside the lens barrel. The thickness T2 of the second shield member 40 is approximately the same as the thickness T1 of the first shield member 30.

[0031] For example, it is preferable that the thickness T2 is 0.1 mm or more and 5 mm or less, the lengths L1 and L2 are 23 mm or more and 140 mm or less, and the inner diameter D3 is 22.6 mm or more and 50 mm or less.

[0032] 5, the third shield member 50 is annular in shape, with an opening 51 for passing multi-beams MB formed in the center of a circular flat plate. The diameter D4 of the opening 51 is approximately the same as the inner diameter D1 of the first cylindrical portion 31 of the first shield member 30.

[0033] The outer diameter D5 of the third shield member 50 is not particularly limited, but it is desirable that the length extend to the edge of the power supply plane of the blanking aperture array substrate 20. This can shield the magnetic field between the blanking aperture array substrate 20 and the first shield member 30 from erupting. The thickness T3 of the third shield member 50 is approximately the same as the thickness T1 of the first shield member 30.

[0034] For example, it is preferable that the thickness T3 is 0.1 mm or more and 5 mm or less, the inner diameter D4 is 23 mm or more and 50 mm or less, and the outer diameter D5 is 24 mm or more and 100 mm or less.

[0035] 1 in which such a shield member S is installed, the electron beam B emitted from the electron gun 111 (emission unit) passes through the reduction lens 115 almost perpendicularly by the illumination lens 112, and illuminates the entire shaping aperture array substrate 10 while the overall shape of the beam is reduced. However, the reduction lens 115 may be provided downstream of the blanking aperture array substrate 20.

[0036] A multi-beam MB including a plurality of electron beams is formed by the electron beam 130 passing through the plurality of openings 12 in the shaping aperture array substrate 10. The multi-beam MB passes through the openings 41 in the second shield member 40 and passes between the corresponding blankers in the blanking aperture array substrate 20.

[0037] The multi-beams MB that have passed through the blanking aperture array substrate 20 pass through the opening 51 of the third shield member 50 , and then pass through the inside of the cylinders of the first cylindrical portion 31 and the second cylindrical portion 32 of the first shield member 30 .

[0038] The multi-beams MB that have passed through the first shield member 30 proceed toward the central opening of the limiting aperture member 116 via an overall blanker 119 for collectively turning off the beams, while the overall shape of the beams is reduced. Here, the electron beams deflected by the blanker on the blanking aperture array substrate 20 move away from the central opening of the limiting aperture member 116 and are blocked by the limiting aperture member 116. On the other hand, the electron beams that are not deflected by the blanker pass through the central opening of the limiting aperture member 116. Blanking control is performed by turning the blanker and overall blanker on and off, and the on / off of the beams is controlled.

[0039] In this way, the limiting aperture member 116 blocks each beam deflected by the multiple blankers to be in a beam-off state. Then, a beam for one shot is formed by the beams that pass through the limiting aperture member 116 from when the beam is turned on until when the beam is turned off.

[0040] The multi-beams that have passed through the limiting aperture member 116 are focused by the objective lens 117 to form a pattern image with the desired reduction ratio. The multi-beams are all deflected in the same direction by the deflector 118, and each beam is irradiated onto its respective irradiation position on the sample 101. When the XY stage 105 is moving continuously, the deflector 118 controls the beam irradiation position so that it follows the movement of the XY stage 105.

[0041] The multiple beams irradiated at one time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of apertures 12 in the shaping aperture array substrate 10 by the desired reduction ratio described above. The drawing apparatus 100 performs drawing operations using a raster scan method or the like in which shot beams are continuously irradiated in order, and when drawing a desired pattern, unnecessary beams are turned off by blanking control.

[0042] A magnetic field is generated by the current flowing through the control circuit of the blanking aperture array substrate 20, which controls blanking. As shown by the arrows in Figure 6, the generated magnetic field is absorbed by the first shield member 30, second shield member 40, and third shield member 50 arranged near the blanking aperture array substrate 20 and emitted from their ends. This allows the magnetic field to escape outside the multi-beam trajectory. Note that a magnetic field is also emitted from the inner diameter portion of each shield member, causing a slight deflection of the beam. However, this effect is negligible because the design is based on simulation results, a printed circuit board model, and experimental results, to minimize the cumulative deflection on the sample 101 surface—that is, to a range within which the beam irradiation position on the sample 101 surface can be adjusted using correction technology.

[0043] A magnetic field may also be generated from the reduction lens 115, but this magnetic field is absorbed by the second shield member 40 arranged above the blanking aperture array substrate 20 and emitted outside the trajectory of the multi-beams.

[0044] In this manner, in this embodiment, the provision of the shield member S shields the magnetic field, allowing the magnetic field to escape outside the trajectory of the multi-beam, preventing the magnetic field from penetrating into the trajectory of the multi-beam and affecting it. This prevents the trajectory of the beam from being bent and the beam irradiation position on the sample surface from shifting, enabling high-precision writing.

[0045] 7, a ring-shaped fourth shield member 60 may be further disposed between the blanking aperture array substrate 20 and the third shield member 50. The fourth shield member 60 is made of a high-permeability material, and has an inner diameter D6 that is approximately the same as the inner diameter D1 of the first cylindrical portion 31 of the first shield member 30, and a thickness T4 that is approximately the same as the thickness T1 of the first shield member 30.

[0046] In the above embodiment, a configuration was described in which the second shielding member 40 uses a rectangular flat plate with a circular opening, and the third shielding member 50 uses a circular flat plate with a circular opening, but the outer shape of the flat plate is not limited to rectangular or circular, and it can be triangular, or any polygon with pentagons or more sides, as long as it does not interfere with the components inside the telescope barrel.

[0047] In the above embodiment, the first shielding member 30 is described as having a first cylindrical portion 31 and a second cylindrical portion 32 connected together, but if it can be placed close enough to the blanking aperture array substrate 20, it may also be cylindrical with a uniform diameter.

[0048] In the lithography apparatus of the above embodiment, the overall blanker 119 deflects the entire multi-beam, and therefore needs to be located a certain distance above the limiting aperture member 116. On the other hand, the first shield member 30 needs to have a certain length so that a magnetic field does not intrude into the trajectory of the multi-beam. In order to satisfy both the requirements for the position of the overall blanker 119 and the length of the first shield member 30, taking into account the size constraints of the electron lens barrel 102, in this embodiment, the first shield member 30 is configured by connecting a first cylindrical portion 31 and a second cylindrical portion 32 having an inner diameter larger than that of the first cylindrical portion 31, and the overall blanker 119 is located inside the second cylindrical portion 32.

[0049] The shield members may be connected to each other using a high magnetic permeability material, and may be connected via a connecting member.

[0050] In each shield member, the shape of the opening through which the beam passes is preferably circular in order to reduce the effects of aberration and distortion on the beam.

[0051] 8 shows the results of a simulation of the cumulative deflection of the beam when the first shield member 30 and the third shield member 50 are installed. For the simulation, Femtet (manufactured by Murata Software Co., Ltd.) was used as analysis software, and the current paths of each power supply layer were modeled based on the circuit layout of the blanking aperture array substrate 20 (the blanking aperture array chip and its mounting substrate). A reduction lens 115 capable of absorbing the magnetic field from the control circuit of the blanking aperture array substrate was also modeled, and a simple model of the interior of the actual electron lens barrel 102 was created.

[0052] Then, the current flowing through the blanking aperture array substrate 20 in an actual drawing device was measured, and the current density distribution was calculated using the measured current value to determine the cumulative deflection amount.

[0053] The vertical axis of the graph shown in Fig. 8 represents the cumulative deflection amount, and the horizontal axis represents the position in the height direction (Z direction). Z=0 corresponds to the position of the blanking aperture array substrate 20. The simulation results shown in Fig. 8 show that the cumulative deflection amount is kept extremely small.

[0054] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0055] 10. Shaped aperture array substrate 20 Blanking aperture array substrate 30 First shield member 40 Second shield member 50 Third shield member 100 drawing device

Claims

1. a blanking aperture array substrate provided with a plurality of blankers for blanking deflection of each of the plurality of charged particle beams constituting the multi-beam; a first shield member that is arranged downstream of the blanking aperture array substrate in the traveling direction of the multi-beams, has a cylindrical portion through which the multi-beams pass, and is made of a high magnetic permeability material; a lens barrel that houses the blanking aperture array substrate and the first shield member; A multi-charged particle beam writing apparatus comprising:

2. 2. The multi-charged particle beam writing apparatus according to claim 1, wherein the first shield member is connected to another shield member directly or via a connecting member made of a highly magnetically permeable material.

3. 2. The multi-charged particle beam lithography apparatus according to claim 1, further comprising: a flat second shield member made of a high magnetic permeability material, the flat second shield member being arranged upstream of the blanking aperture array substrate in a traveling direction of the multi-beams, the flat second shield member having a circular aperture through which the multi-beams pass.

4. The second shield member has the circular opening formed in the center of a flat plate, 4. The multi-charged particle beam drawing apparatus according to claim 3, wherein the diameter of said circular opening is not less than 22.6 mm and not more than 50 mm.

5. a shaping aperture array substrate including a plurality of apertures through which portions of the charged particle beam pass to form the multi-beam; 4. The multi-charged particle beam writing apparatus according to claim 3, wherein the second shield member is disposed between the shaping aperture array substrate and the blanking aperture array substrate.

6. 2. The multi-charged particle beam writing apparatus according to claim 1, further comprising: a flat-plate-shaped third shield member made of a highly permeable material, the third shield member being disposed between the blanking aperture array substrate and the first shield member, the third shield member having a circular opening through which the multi-beams pass.

7. the third shield member has the circular opening formed in the center of a flat plate, 7. The multi-charged particle beam drawing apparatus according to claim 6, wherein the diameter of said circular opening is 23 mm or more and 50 mm or less.

8. 7. The multi-charged particle beam writing apparatus according to claim 6, further comprising a ring-shaped fourth shield member made of a high magnetic permeability material and disposed between said blanking aperture array substrate and said third shield member.

9. the first shield member has a first cylindrical portion and a second cylindrical portion having an inner diameter larger than that of the first cylindrical portion, 2. The multi-charged particle beam writing apparatus according to claim 1, wherein a lower edge of said first cylindrical portion and an upper edge of said second cylindrical portion are connected to each other.

10. 10. The multi-charged particle beam drawing apparatus according to claim 9, wherein the thickness of the first shield 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.

11. 2. The multi-charged particle beam drawing apparatus according to claim 1, wherein the first shield member is made of an alloy containing iron, nickel, or cobalt, and having a relative magnetic permeability of 1 or more.

12. 12. The multi-charged particle beam writing apparatus according to claim 11, wherein the first shield member is made of permalloy.

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