Electron gun, and electron beam lithography device

Abstract

PURPOSE: To provide a device capable of suppressing a backflow of cations, which are generated by collision of electrons after passing an opening of an anode electrode, to a cathode.CONSTITUTION: An electron gun 201 comprises: a cathode 10 which emits an electron beam; an anode 14 which includes a face opposed to the cathode, in which a first opening through which the electron beam emitted from the cathode is passed is formed on the face and at least one second opening is formed on the same face as that on which the first opening is formed and at a position different from the first opening and which is retained at a potential of a positive side in relative to a potential of the electron beam; a restriction aperture substrate 16 which is disposed on a downstream side of the anode electrode in a direction of travel of the electron beam, in which a third opening is formed through which the electron beam is passed, and which restricts the passage of a part of the electron beam; and a Wehnelt 12 which is disposed between the cathode and the anode and to which a potential of a negative side in relative to the potential of the anode is applied.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an electron gun and an electron beam lithography system, and more particularly to an electron source mounted in, for example, a multi-beam lithography system. [Background technology]

[0002] Lithography technology, which is responsible for the advancement of miniaturization of semiconductor devices, is the only extremely important process in semiconductor manufacturing that generates patterns. In recent years, with the increasing integration density of LSIs, the circuit line width required for semiconductor devices has been getting finer year by year. Here, electron beam (EB) lithography technology has inherently excellent resolution, and lithography is carried out using an electron beam to draw on wafers, etc.

[0003] For example, there is a lithography system that uses multiple beams. Compared to lithography using a single electron beam, using multiple beams allows for the irradiation of many beams at once, thereby significantly improving throughput. In such a lithography system, for example, an electron beam emitted from an electron gun is passed through a mask with multiple holes to form multiple beams, each of which is blanked, and the unblocked beams are reduced in size by an optical system, deflected by a deflector, and irradiated onto the desired position on the sample.

[0004] In the electron gun that emits the electron beam, a portion of the electron beam collides with the aperture substrate after passing through the anode electrode, generating secondary electrons or reflected electrons that generate positive ions from gas molecules in the atmosphere. If these positive ions then flow back and collide with the cathode (emitter) surface, damaging the crystal, there is a problem in that an electron beam with sufficient current distribution cannot be obtained. A cathode that does not produce an electron beam with sufficient current distribution must be replaced.

[0005] Here, a technology has been disclosed for an electron gun mounted on an X-ray device, in which multiple exhaust paths are formed on the side of a cylindrical electron passing hole located on the cathode side of the anode electrode surface, and the pressure inside the electron passing hole is reduced through the exhaust paths, thereby reducing the number of generated positive ions (see, for example, Patent Document 1). However, there is a problem in that the risk of discharge increases if a cylindrical member with a positive potential relative to the cathode is located on the cathode side of the anode electrode surface. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-256441 Summary of the Invention [Problem to be solved by the invention]

[0007] One aspect of the present invention provides a device capable of suppressing the backflow of positive ions to the cathode caused by collision with electrons after passing through an opening in an anode electrode. [Means for solving the problem]

[0008] An electron gun according to one aspect of the present invention comprises: a cathode that emits an electron beam; an anode electrode having a surface facing the cathode, in which a first opening is formed to allow the electron beam emitted from the cathode to pass, and in which at least one second opening is formed on the same surface as the first opening but at a position different from the first opening, and which is maintained at a positive potential relative to the potential of the cathode; a limiting aperture substrate disposed downstream of the anode electrode in the direction of travel of the electron beam, having a third opening formed therein through which the electron beam passes and limiting passage of a portion of the electron beam; a Wehnelt electrode disposed between the cathode and the anode, to which a negative potential relative to the potential of the anode is applied; The present invention is characterized by the following.

[0009] Preferably, at least one second opening is larger in size than the first opening.

[0010] Furthermore, it is preferable that the distance from the center of the first opening to the center of the second opening satisfy a quadratic equation using the distance between the anode electrode and the Wehnelt electrode as a parameter.

[0011] The distance y from the center of the first opening to the center of the second opening is calculated using the following equation, which uses the distance x between the anode electrode and the Wehnelt electrode as a parameter: y=0.037x 2 -1.333x+14.667±1.000 It is preferable that the following is satisfied.

[0012] Preferably, as the at least one second opening, a plurality of second openings are formed rotationally symmetrically about the center of the first opening.

[0013] Preferably, the light-emitting element further comprises a protrusion formed so as to extend from the rear surface opposite to the surface of the anode electrode toward the limiting aperture substrate and disposed near the outer periphery of at least one second opening.

[0014] An electron beam lithography apparatus according to one aspect of the present invention comprises: a stage on which a sample is placed; a cathode that emits an electron beam; an anode electrode having a surface facing the cathode, in which a first opening is formed to allow the electron beam emitted from the cathode to pass, and in which at least one second opening is formed on the same surface as the first opening but at a position different from the first opening, and which is maintained at a positive potential relative to the potential of the cathode; a limiting aperture substrate disposed downstream of the anode electrode in the direction of travel of the electron beam, having a third opening formed therein through which the electron beam passes and limiting passage of a portion of the electron beam; a Wehnelt electrode disposed between the cathode and the anode, to which a negative potential relative to the potential of the anode is applied; an electron gun having an electron optical system that guides the electron beam emitted from the electron gun to the sample; The present invention is characterized by the following.

[0015] Preferably, at least one second opening is larger in size than the first opening. [Effects of the Invention]

[0016] According to one aspect of the present invention, it is possible to suppress or reduce the backflow of positive ions to the cathode, which are generated due to collision with electrons after passing through the opening of the anode electrode. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a conceptual diagram showing a configuration of a drawing device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of a circuit configuration of an electron gun and a high-voltage power supply circuit according to the first embodiment. [Figure 3] FIG. 2 is a top view showing an example of the configuration of an anode electrode according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing an example of the internal configuration of an electron gun in a comparative example to the first embodiment. [Figure 5] FIG. 2 is a diagram showing an example of the internal configuration of the electron gun according to the first embodiment. [Figure 6] FIG. 10 is a diagram showing an example of a simulation result illustrating a state of backflow of positive ions in a comparative example to the first embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed at a position away from the electron beam passage hole by a distance y1 in the first embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed at a position away from the electron beam passage hole by a distance y2 in the first embodiment. [Figure 9] FIG. 10 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed at a position away from the electron beam passing aperture by a distance y3 in the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed with a diameter size D21 according to the first embodiment. [Figure 11] FIG. 10 is a diagram showing an example of a simulation result showing a state of backflow of positive ions when an opening is formed with a diameter size D22 according to the first embodiment. [Figure 12] FIG. 10 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed with a diameter size D23 according to the first embodiment. [Figure 13] FIG. 2 is a diagram showing a positional relationship within the electron gun according to the first embodiment. [Figure 14] FIG. 4 is a diagram showing an example of a graph illustrating the relationship between the optimum distance from the passage hole of the anode to the opening and the distance between the anode and the Wehnelt in the first embodiment. [Figure 15] FIG. 4 is a diagram showing an example of a table showing the relationship between the optimum distance from the passage hole of the anode to the opening and the distance between the anode and the Wehnelt in the first embodiment. [Figure 16] FIG. 2 is a diagram showing an example of the internal configuration of an electron gun in a first modification of the first embodiment. [Figure 17] FIG. 10 is a diagram showing an example of the internal configuration of an electron gun in a second modification of the first embodiment. [Figure 18] FIG. 10 is a diagram showing another example of the turning of the rear surface of the anode in the second modification of the first embodiment. [Figure 19] FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate according to the first embodiment. [Figure 20] 2 is a cross-sectional view showing the configuration of a blanking aperture array mechanism in the first embodiment. FIG. [Figure 21] FIG. 2 is a conceptual diagram for explaining an example of a drawing operation in the first embodiment. [Figure 22]3 is a diagram showing an example of a multi-beam irradiation area and a pixel to be written in the first embodiment. FIG. [Figure 23] FIG. 2 is a diagram for explaining an example of a multi-beam writing operation according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] In the following embodiments, a configuration using multiple electron beams will be described, but the electron beam is not limited to multiple beams and may be a single beam.

[0019] Embodiment 1 FIG. 1 is a conceptual diagram showing the configuration of a lithography apparatus according to the first embodiment. In FIG. 1, the lithography apparatus 100 includes a lithography mechanism 150 and a control circuit 160. The lithography apparatus 100 is an example of a multi-electron beam lithography apparatus and also an example of a multi-electron beam exposure apparatus. The lithography mechanism 150 includes an electron gun chamber 106, an electron lens barrel 102 (electron beam column), and a lithography chamber 103. The electron gun chamber 106 is disposed above the electron lens barrel 102. The electron lens barrel 102 is disposed above the lithography chamber 103.

[0020] An electron gun 201 is disposed in the electron gun chamber 106. An electron optical system, such as an illumination lens 202, a shaping aperture array substrate 203, a blanking aperture array mechanism 204, a reduction lens 205, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, and a sub-deflector 209, is disposed in the electron lens barrel 102.

[0021] An XY stage 105 is disposed within the patterning chamber 103. A sample 101, such as a mask, which will be the patterned substrate during patterning (exposure) is disposed on the XY stage 105. The sample 101 includes an exposure mask used in manufacturing a semiconductor device, or a semiconductor substrate (silicon wafer) on which a semiconductor device is manufactured. The sample 101 also includes a mask blank coated with resist and on which nothing has yet been patterned. A mirror 210 for measuring the position of the XY stage 105 is also disposed on the XY stage 105.

[0022] The control system circuit 160 includes a control computer 110, a memory 112, a high-voltage power supply circuit 120, a deflection control circuit 130, digital-to-analog conversion (DAC) amplifier units 132 and 134, a lens control circuit 136, a stage control mechanism 138, a stage position measurement device 139, and a storage device 140 such as a magnetic disk drive. The control computer 110, the memory 112, the high-voltage power supply circuit 120, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, the stage position measurement device 139, and the storage device 140 are connected to one another via a bus (not shown). The deflection control circuit 130 is connected to the DAC amplifier units 132 and 134 and a blanking aperture array mechanism 204. The sub-deflector 209 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 130 via the DAC amplifier 132. The main deflector 208 is composed of four or more electrodes, and each electrode is controlled by a deflection control circuit 130 via a DAC amplifier 134. A group of lenses, including an illumination lens 202, a reduction lens 205, and an objective lens 207, is controlled by a lens control circuit 136. The electron gun 201 is controlled by a high-voltage power supply circuit 120.

[0023] The high-voltage power supply circuit 120, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, and the stage position measuring device 139 are controlled by a control computer 110. Information input to the control computer 110 and information calculated within the control computer 110 are stored in a memory 112.

[0024] Furthermore, chip data (drawing data) of a chip including a plurality of graphic patterns is input from the outside to the drawing device 100 and stored in the storage device 140. The chip data defines information on a plurality of graphic patterns that constitute the chip pattern. Specifically, for each graphic pattern, for example, the coordinates of each vertex are defined in the order in which the graphic is formed. Alternatively, for each graphic pattern, for example, a graphic code, coordinates, size, etc. are defined.

[0025] The control computer 110 reads out the drawing data from the storage device 140, performs multiple stages of data processing, and controls the high-voltage power supply circuit 120, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, and the stage position measuring device 139 in accordance with the drawing sequence.

[0026] The illumination lens 202, reduction lens 205, and objective lens 207 are all made up of electromagnetic lenses, and a reduction optical system is made up of the reduction lens 205 and objective lens 207. The illumination lens 202 functions as a collimator lens.

[0027] The position of the XY stage 105 is controlled by driving motors (not shown) for each axis controlled by a stage control mechanism 138. A stage position measuring device 139 receives light reflected from a mirror 210 and measures the position of the XY stage 105 based on the principle of laser interferometry.

[0028] The electron gun 201 has a thermionic emission type cathode 10, a Wehnelt 12 (Wehnelt electrode), an anode 14 (anode electrode), and a limiting aperture substrate 16. The Wehnelt 12 is disposed between the cathode 10 and the anode 14. The limiting aperture substrate 16 is disposed downstream of the anode 14 in the traveling direction of the electron beam 200. Since the Wehnelt 12 and the anode 14 function as electrodes, they are naturally made of conductive materials.

[0029] 1 shows the configuration necessary for explaining the first embodiment. The drawing device 100 may also include other configurations that are normally required.

[0030] FIG. 2 is a diagram showing an example of the circuit configuration of the electron gun and high-voltage power supply circuit in the first embodiment. In the example of FIG. 2, a passage hole 11 (first opening) is formed in the anode 14 to allow the electron beam 200 emitted from the cathode 10 to pass therethrough. The anode 14 is grounded and its potential is set to ground (GND) potential. In other words, the anode 14 is maintained at a potential that is positive relative to the potential of the electron beam 200. A high-voltage power supply circuit 120 is connected to the electron gun 201. The high-voltage power supply circuit 120 applies an acceleration voltage between the cathode 10 and the anode 14. As the acceleration voltage, a negative potential is applied to the cathode 10 relative to the anode 14, which is at ground potential. The high-voltage power supply circuit 120 also applies a negative bias voltage to the Wehnelt 12. In other words, the Wehnelt 12 is disposed between the cathode 10 and the anode 14, and a negative potential is applied to the Wehnelt 12 relative to the potential of the anode 14. The specific details will be explained below.

[0031] The high-voltage power supply circuit 120 includes an accelerating voltage power supply 62, a Wehnelt power supply 64, and a heater power supply 66. The cathode (-) side of the accelerating voltage power supply 62 is connected to the cathode 10 via a heater 59 inside the electron gun 201. The anode (+) side of the accelerating voltage power supply 62 is connected to the anode 14 (anode electrode) inside the electron gun 201 and is also connected to ground. An ammeter 70 is connected in series between the anode (+) of the accelerating voltage power supply 62 and the anode 14. The cathode (-) of the accelerating voltage power supply 62 is also branched and connected to the anode (+) of the Wehnelt power supply 64, and the cathode (-) of the Wehnelt power supply 64 is connected to the Wehnelt 12 (Wehnelt electrode) located between the cathode 10 and the anode 14. The heater power supply 66 is connected to the heater 59.

[0032] When emitting an electron beam, the atmosphere in which the electron gun 201 is placed is maintained in a vacuum state at a predetermined pressure by a vacuum pump (not shown), and then a constant negative Wehnelt voltage (bias voltage) is applied to the Wehnelt 12 from the Wehnelt power supply 64, and a constant negative acceleration voltage is applied to the cathode 10 from the acceleration voltage power supply 62. In this state, when the cathode 10 is heated by the heater 59, an electron beam (group of electrons) is emitted from the cathode 10, and the emitted electron beam (group of electrons) is accelerated by the acceleration voltage and travels toward the anode 14.

[0033] FIG. 3 is a top view showing an example of the configuration of the anode electrode in the first embodiment. In the examples of FIGS. 2 and 3, the anode 14 has, for example, a disk-shaped electrode substrate 7. The surface of the electrode substrate 7 faces the cathode 10. In other words, the anode 14 has a surface facing the cathode 10, and a passage hole 11 (first opening) is formed on this surface to allow the electron beam 200 emitted from the cathode 10 to pass through. The passage hole 11 is preferably formed in the center of the electrode substrate 7. At the same time, the anode 14 has at least one opening 15 (second opening) formed on the same surface as the passage hole 11 but at a position different from the passage hole 11. For example, at least one opening 15 (second opening) larger in size than the passage hole 11 is formed.

[0034] As shown in the examples of FIGS. 2 and 3, it is preferable that a plurality of passage holes 15 are formed rotationally symmetrically about the center of the passage hole 11 as at least one passage hole 15 .

[0035] The electron beam 200 that has passed through the passage hole 11 of the anode 14 proceeds toward the limiting aperture substrate 16. The limiting aperture substrate 16 is formed with a passage hole 17 (third opening) through which the electron beam 200 passes, and limits the passage of part of the electron beam 200. For example, the passage hole 17 blocks a beam that is wider than the desired emission angle. The passage hole 17 also blocks scattered electrons, etc.

[0036] 2, the anode 14 has a support cylinder 8 that extends cylindrically from the outer periphery of the electrode substrate 7 to the downstream side in the traveling direction of the electron beam 200. The anode 14 is supported on the limiting aperture substrate 16 via the support cylinder 8. The limiting aperture substrate 16 is preferably made of a conductive material. In this case, the ground potential is applied to the limiting aperture substrate 16 via the anode 14.

[0037] FIG. 4 is a diagram showing an example of the internal configuration of an electron gun in a comparative example to the first embodiment. FIG. 5 is a diagram showing an example of the internal configuration of the electron gun according to the first embodiment. In Fig. 4, an electron beam 500 emitted from a cathode 510 is accelerated by an acceleration voltage and a bias voltage applied to a Wehnelt 512, and passes through a passage hole 511 in an anode 514. The electron beam then travels to a limiting aperture substrate 516. In Fig. 4, the crossover formed near the Wehnelt 512 is not shown. This also applies to the following figures. In Figure 4, a portion of the electron beam 500 passing through the anode 514 collides with the limiting aperture substrate 516, emitting secondary electrons or backscattered electrons. Generally, the electron gun chamber is baked to promote gas generation from the chamber, creating a high vacuum inside and minimizing the amount of gas molecules that serve as ion seeds. However, secondary electrons or backscattered electrons collide with remaining gas molecules that cannot be completely evacuated, generating positive ions 521. The positive ions 521 generated below the anode 514 are attracted by the space charge, pass through the passage hole 511, and collide with the cathode 510 along the electron beam 500. This damage damages the crystals that make up the cathode 510, creating local depressions. This results in problems such as insufficient current distribution. When the cathode 510 is damaged in this way, it must be replaced.

[0038] In the first embodiment shown in FIG. 5 , as in the comparative example, the electron beam 200 emitted from the cathode 10 is accelerated by the accelerating voltage and the bias voltage applied to the Wehnelt 12 and passes through the passage hole 11 of the anode 14. The electron beam then travels to the limiting aperture substrate 16. A portion of the electron beam 200 that has passed through the anode 14 collides with the limiting aperture substrate 16, emitting secondary electrons or reflected electrons. Therefore, even in the first embodiment, even when the electron gun chamber 106 is baked, the secondary electrons or reflected electrons collide with gas molecules that have not been completely evacuated, generating positive ions 21, as in the comparative example. However, in the first embodiment, as shown in FIG. 5 , at least one opening 15 of a different size from the passage hole 11 is formed around the passage hole 11 of the anode 14. For example, at least one opening 15 of a larger size than the passage hole 11 is formed. The opening 15 is preferably, but not limited to, a circular shape. The shape of the opening 15 is not limited as long as it has an area larger than the area of ​​the passage hole 11. For example, the opening 15 may be elliptical or rectangular, or may be arc-shaped.

[0039] Furthermore, the opening 15 is larger in size than the passage hole 11. Therefore, the larger the opening area, the larger the conductance and the higher the probability that positive ions will pass through. As a result, many positive ions 21 can escape into the electron gun chamber 106 outside the anode 14 through the opening 15, which is formed at a position different from the electron beam trajectory.

[0040] As shown in FIG. 5 , the cathode 10 and Wehnelt 12 maintain a negative potential relative to the anode 14, while the anode 14 maintains a positive potential relative to the cathode 10. Therefore, an electric field is generated between them. The opening 15 formed on the surface facing the cathode 10 allows the electric field E to leak into the opening 15. As a result, the positive ions 21 are attracted by the electric field E. If the size of the opening 15 were smaller than the passage hole 11, the positive ions 21 would be attracted to the passage hole 11. However, in the first embodiment, the size of the opening 15 is larger than the passage hole 11. In addition to the improvement in conductance described above, the electric field can attract more positive ions 21 to the opening 15. Therefore, more positive ions 21 can escape from the opening 15, which is formed at a position different from the electron beam trajectory, into the electron gun chamber 106 outside the anode 14. As a result, the number of positive ions that pass through the passage hole 11 and collide with the cathode 10 can be suppressed or reduced. When the opening 15 is to be smaller than the passing hole 11, it is preferable to form a plurality of openings 15 so that the total opening area is larger than the passing hole 11.

[0041] Furthermore, in the first embodiment, the electrode substrate 7 of the anode 14 is disposed so as to face the cathode 10, and no structure having the same potential is disposed on the electrode substrate 7, so that the risk of discharge can be avoided or reduced.

[0042] Furthermore, as shown in the example of FIG. 3, by arranging a plurality of openings 15 in rotational symmetry (equidistant), the distribution of the released positive ions is less likely to be biased, and the positive ions 21 can be efficiently released from the back surface side of the anode 14.

[0043] Next, optimization of the opening 15 will be described.

[0044] FIG. 6 is a diagram showing an example of a simulation result illustrating a state of backflow of positive ions in a comparative example to the first embodiment. FIG. 7 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed at a position spaced a distance y1 from the electron beam passage hole in the first embodiment. FIG. 8 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed at a position spaced a distance y2 from the electron beam passage hole in the first embodiment. FIG. 9 is a diagram showing an example of a simulation result showing a state of a backflow of positive ions when an opening is formed at a position spaced a distance y3 from the electron beam passage hole in the first embodiment. In Figures 7 to 9, the relationship is y3 > y2 > y1. Here, for example, a case where y1 = 3 mm, y2 = 5 mm, and y3 = 10 mm is shown as an example. Also, in the examples of Figures 7 to 9, a case where the distance between the anode and the Wehnelt is 15 mm is shown as an example. In the comparative example, as shown in Figure 6, it can be seen that many positive ions flow back toward the cathode from the electron beam passing holes. In contrast, by forming the opening 15 at a distance y1, it can be seen that the amount of positive ions emitted from the opening 15 can be increased, and conversely, the amount of positive ions emitted from the electron beam passing holes can be reduced. Furthermore, it can be seen that by forming the opening 15 at a distance y2, it can be seen that the amount of positive ions emitted from the opening 15 can be further increased, and conversely, the amount of positive ions emitted from the electron beam passing holes can be further reduced. However, when the opening 15 is formed at a distance y3, the amount of positive ions emitted from the opening 15 is less than when the distance is y2, and although the amount of positive ions emitted from the electron beam passage hole can be made less than in the comparative example, conversely, the amount of positive ions emitted from the electron beam passage hole 11 becomes greater than when the distances are y1 and y2. Thus, it can be seen that an optimum solution exists for the distance from the electron beam passage hole 11 to the opening 15.

[0045] FIG. 10 shows an example of a simulation result showing a state of backflow of positive ions when an opening having a diameter of D21 is formed in the first embodiment. FIG. 11 is a diagram showing an example of a simulation result indicating the state of backflow of positive ions when an opening is formed with a diameter size D22 in Embodiment 1. FIG. 12 is a diagram showing an example of a simulation result indicating the state of backflow of positive ions when an opening is formed with a diameter size D23 in Embodiment 1. In FIGS. 10 to 12, there is a relationship of D21 < D22 < D23. The diameter sizes are all larger than the diameter of the electron beam passage hole 11. In the example of FIG. 10, a case where the diameter size D21 is 1 mm larger than the diameter size D1 of the electron beam passage hole 11 is shown. In the example of FIG. 11, a case where the diameter size D22 is 2 mm larger than the diameter size D1 of the electron beam passage hole 11 is shown. In the example of FIG. 12, a case where the diameter size D23 is 3 mm larger than the diameter size D1 of the electron beam passage hole 11 is shown. As shown in the examples of FIGS. 10 to 12, it can be seen that the change in the diameter size of the opening 15 has little effect on the amount of positive ions released from the electron beam passage hole 11.

[0046] FIG. 13 is a diagram showing the positional relationship inside the electron gun in Embodiment 1. In FIG. 13, the distance x between the Wehnelt 12 and the anode 14 and the distance y from the passage hole 11 of the anode 14 to the opening 15 are shown. The distance y indicates the distance between the centers. Also, the diameter size D1 of the electron beam passage hole 11 and the diameter size D2 of the opening 15 are shown.

[0047] FIG. 14 is a diagram showing an example of a graph indicating the relationship between the optimal distance from the passage hole of the anode to the opening and the distance between the anode and the Wehnelt in Embodiment 1. The diameter of the passage hole 11 of the anode is 2 mm. In FIG. 14, the vertical axis indicates the distance y from the passage hole 11 of the anode 14 to the opening 15. The horizontal axis indicates the distance x between the anode and the Wehnelt. As shown in FIG. 14, the optimal distance y from the center of the passage hole 11 to the center of the opening 15 satisfies a quadratic equation using the distance x between the anode 14 and the Wehnelt 12 as a parameter. Specifically, the optimal distance y from the center of the passage hole 11 to the center of the opening 15 satisfies the following formula (1) using the distance x between the anode 14 and the Wehnelt 12 as a parameter. (1) y=0.037x 2 -1.333x+14.667

[0048] Furthermore, when the anode-Wehnelt distance (x) was 15 mm, as shown in Figures 7 and 8, there was no significant difference in the effects between when the distance y was 3 mm and when the distance y2 was 5 mm, and both were good. Although not shown, when the distance y was 1 mm, the amount of positive ions emitted from the electron beam passage hole 11 was large, and good effects were not obtained. From these results, it can be seen that a margin of 2 mm is acceptable for the distance y. In other words, a margin of ±1 mm from the optimal value is acceptable for the distance y. Therefore, it is preferable that the distance y from the center of the passage hole 11 to the center of the opening 15 satisfies the following equation (2), which uses the distance x between the anode 14 and the Wehnelt 12 as a parameter. The units of the distances x and y are both mm. (2) y=0.037x 2 -1.333x+14.667±1.000

[0049] FIG. 15 is a diagram showing an example of a table illustrating the relationship between the optimal distance from the anode passage hole to the opening and the anode-Wehnelt distance in the first embodiment. FIG. 15 shows the results when the acceleration voltage V0 between the cathode 10 and the anode 14 is −50 kV≦V0<0. In the example of FIG. 15, based on the results of the graph in FIG. 14, when the anode-Wehnelt distance is 6 to 12 mm, the optimal distance from the anode passage hole 11 to the opening 15 is 5 to 10 mm. When the anode-Wehnelt distance is 12 to 15 mm, the optimal distance from the anode passage hole 11 to the opening 15 is 3 to 5 mm. It was also found that when the anode-Wehnelt distance is less than 6 mm, the distance is too close, resulting in a strong electric field in the center and a reduced effect of escaping positive ions through the opening 15. The relationship in FIG. 15 also holds true when the acceleration voltage V0 is more negative than −50 kV.

[0050] FIG. 16 is a diagram showing an example of the internal configuration of an electron gun in Modification 1 of Embodiment 1. The modification of Embodiment 1 in FIG. 16 is similar to FIG. 5 except that at least one opening 17 is formed in the side surface of the support cylinder 8 of the anode 14. By forming at least one opening 17 in the side surface of the support cylinder 8, it is possible to improve the efficiency of exhausting gas from inside the support cylinder 8 during exhaust using a vacuum pump (not shown). As a result, it is possible to reduce the number of generated positive ions 21. It is more preferable to arrange a plurality of openings 17 at equal intervals as the at least one opening 17.

[0051] FIG. 17 is a diagram showing an example of the internal configuration of an electron gun according to Modification 2 of Embodiment 1. Modification 2 of FIG. 17 further includes a barb 18 (protrusion) extending from the rear surface of the anode 14 opposite the surface facing the cathode 10 toward the limiting aperture substrate 16. The remaining configuration is the same as that of FIG. 5. The barb 18 is disposed near the outer periphery of at least one opening 15. The example of FIG. 17 shows a case in which the barb 18 is arranged in a cylindrical shape along the outer periphery of the opening 15. By disposing the barb 18 in each opening 15, it is possible to easily temporarily confine positive ions 21 in the space surrounded by the rear surface of the electrode substrate 7, the inner surface of the support cylinder 8, and the limiting aperture substrate 16. This increases the number of times positive ions collide with the rear surface of the electrode substrate 7 and the inner surface of the support cylinder 8. This allows the energy of the positive ions 21 to be attenuated. Therefore, even if positive ions 21 flow back from the electron beam passage hole 11 to the cathode 10, the impact on the crystal that becomes the cathode 10 can be reduced. Although the provision of the barbs 18 makes it difficult for the positive ions 21 to pass through the opening 15, it is possible to emit a larger number of positive ions from the opening 15 than the number of positive ions that pass through the electron beam passing hole 11. If the length L of the barbs 18 is too long, it becomes too difficult for the positive ions 21 to be emitted from the opening 15, so it is preferable to form the length L of the barbs 18 to be equal to or smaller than the diameter size D2 of the opening 15.

[0052] 18 is a diagram showing another example of the return on the back surface of the anode in Modification 2 of Embodiment 1. The example of Fig. 18 shows a case where the return 18 is arranged so as to surround the opening 15, with the return 18 being cylindrical and having a diameter larger than the outer periphery of the opening 15. In this way, the position of the return 18 does not need to coincide with the outer periphery of the opening 15.

[0053] In the above example, each of the barbs 18 is arranged to surround the entire periphery of one of the openings 15, but this is not limiting. A portion of the periphery of the opening 15 may be provided that is not blocked by the barbs 18. Furthermore, barbs 18 may not be arranged on all of the openings 15, but may be arranged on some of the openings 15.

[0054] FIG. 19 is a conceptual diagram showing the configuration of a shaping aperture array substrate in the first embodiment. In FIG. 19, holes (openings) 22 are formed in a matrix of p columns (y direction) by q columns (x direction) (p, q≧2) at a predetermined arrangement pitch in shaping aperture array substrate 203. In the example of FIG. 2, for example, 24×24 columns of holes 22 are formed in the vertical and horizontal directions (x, y directions). The number of holes 22 is not limited to this. For example, 512×512 columns of holes 22 may be formed. Each hole 22 is formed as a rectangle of the same size and shape. Alternatively, each hole 22 may be a circle of the same diameter. A portion of electron beam 200 passes through each of these multiple holes 22, thereby forming multiple beams 20. In other words, shaping aperture array substrate 203 forms multiple beams 20.

[0055] 20 is a cross-sectional view showing the configuration of the blanking aperture array mechanism according to the first embodiment. As shown in FIG. 20, the blanking aperture array mechanism 204 includes a blanking aperture array substrate 31, which is made of a semiconductor substrate such as silicon, and is disposed on a support base 33. In a central membrane region 330 of the blanking aperture array substrate 31, passage holes 25 (openings) for passing each beam of the multi-beams 20 are formed at positions corresponding to the holes 22 of the shaping aperture array substrate 203 shown in FIG. 19. Pairs of control electrodes 24 and counter electrodes 26 (blankers: blanking deflectors) are disposed at positions facing each other across the corresponding passage holes 25 among the plurality of passage holes 25. Furthermore, a control circuit 41 (logic circuit) is disposed inside the blanking aperture array substrate 31 near each passage hole 25, which applies a deflection voltage to the control electrode 24 for each passage hole 25. The counter electrodes 26 for each beam are connected to ground.

[0056] An amplifier (an example of a switching circuit), not shown, is disposed within the control circuit 41. As an example of the amplifier, a CMOS (Complementary MOS) inverter circuit serving as a switching circuit is disposed. To the input (IN) of the CMOS inverter circuit, either an L (low) potential (e.g., ground potential) that is lower than the threshold voltage or an H (high) potential (e.g., 1.5 V) that is equal to or higher than the threshold voltage is applied as a control signal. In the first embodiment, when an L potential is applied to the input (IN) of the CMOS inverter circuit, the output (OUT) of the CMOS inverter circuit applied to the control circuit 41 becomes a positive potential (Vdd), and the corresponding beam is deflected by an electric field due to the potential difference with the ground potential of the counter electrode 26, and is controlled so that the beam is turned OFF by being shielded by the limiting aperture substrate 206. On the other hand, when an H potential is applied to the input (IN) of the CMOS inverter circuit (active state), the output (OUT) of the CMOS inverter circuit becomes the ground potential, and there is no potential difference with the ground potential of the opposing electrode 26, so the corresponding beam is not deflected, and the beam is controlled to be ON by passing through the limiting aperture substrate 206. Blanking control is performed by this deflection.

[0057] Next, a specific example of the operation of the writing mechanism 150 will be described. An electron beam emitted from the electron gun 201 is guided to the sample 101 by an electron optical system. Specifically, the operation is as follows: An electron beam 200 emitted from the electron gun 201 (emission source) is illuminated almost perpendicularly onto the entire shaping aperture array substrate 203 by an illumination lens 202. A plurality of rectangular holes 22 (openings) are formed in the shaping aperture array substrate 203, and the electron beam 200 illuminates an area including all of the holes 22. Portions of the electron beam 200 irradiated onto the positions of the holes 22 pass through the holes 22 of the shaping aperture array substrate 203, thereby forming, for example, a rectangular multibeam (multiple electron beams) 20. The multibeam 20 passes through corresponding blankers of the blanking aperture array mechanism 204. Each blanker performs blanking control on the beams passing through it so that the beams are turned on for a set writing time (irradiation time).

[0058] The multi-beams 20 that pass through the blanking aperture array mechanism 204 are reduced by the reduction lens 205 and travel toward a central hole formed in the limiting aperture substrate 206. Here, the electron beams deflected by the blankers of the blanking aperture array mechanism 204 are shifted from the central hole of the limiting aperture substrate 206 and are blocked by the limiting aperture substrate 206. On the other hand, the electron beams that are not deflected by the blankers of the blanking aperture array mechanism 204 pass through the central hole of the limiting aperture substrate 206 as shown in FIG. 1. In this way, the limiting aperture substrate 206 blocks each beam that is deflected by the blankers of the blanking aperture array mechanism 204 to be in a beam-off state. Then, each beam of one shot is formed by the beams that pass through the limiting aperture substrate 206 from when the beams are turned on until when they are turned off. The multibeams 20 that have passed through the limiting aperture substrate 206 are focused by the objective lens 207 to form a pattern image with the desired reduction ratio, and the entire multibeams 20 that have passed through the limiting aperture substrate 206 are deflected in the same direction by the main deflector 208 and the sub-deflector 209, and each beam is irradiated onto its respective irradiation position on the sample 101. Furthermore, for example, when the XY stage 105 is moving continuously, tracking control is performed by the main deflector 208 so that the beam irradiation position follows the movement of the XY stage 105. Ideally, the multibeams 20 that are irradiated at one time are arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes 22 in the shaping aperture array substrate 203 by the desired reduction ratio described above.

[0059] 21 is a conceptual diagram for explaining an example of the writing operation in the first embodiment. As shown in FIG. 21, the writing region 30 (bold line) of the sample 101 is virtually divided into a plurality of rectangular stripe regions 32 with a predetermined width in the y direction, for example. The example of FIG. 21 shows a case where the writing region 30 of the sample 101 is divided into a plurality of stripe regions 32 with a width substantially equal to the size of the designed irradiation region 34 (writing field) that can be irradiated with one irradiation of the multibeam 20, for example. Next, an example of the writing operation will be described.

[0060] First, the XY stage 105 is moved and adjusted so that the irradiation area 34 of the multi-beam 20 is positioned at the left end of the first stripe region 32 or further to the left. Then, when writing the first stripe region 32, the XY stage 105 is moved, for example, in the -x direction, thereby relatively progressing writing in the x direction. The XY stage 105 is moved continuously at a constant speed, for example.

[0061] After the writing of the first stripe region 32 is completed, the stage position is moved in the −y direction by the width of the stripe region 32. As a result, the written stripe region 32 is shifted in the y direction by the width of the stripe region 32.

[0062] Next, the irradiation area 34 of the multi-beam 20 is adjusted to be located at the right end of the second stripe area 32, or at a position further to the right. Then, by moving the XY stage 105, for example, in the +x direction, writing proceeds relatively in the -x direction. This completes writing of the second stripe area 32. By repeating this process thereafter, writing of all the stripe areas 32 is completed.

[0063] By alternating the direction of writing in this way, the stage movement time can be shortened, and ultimately the writing time can be shortened. In one shot, multiple shot patterns, up to the same number as the holes 22, are formed at once by the multiple beams formed by passing through each hole 22 in the shaping aperture array substrate 203.

[0064] 21 shows the case where the stripe regions 32 are drawn in order while the direction is alternately changed, but the present invention is not limited to this. The stripe regions 32 may be drawn in the same direction.

[0065] 21 shows the case where drawing is performed once for each pixel, but this is not limiting. Multiple drawing may be performed, in which drawing is performed multiple times for each pixel by having the XY stage 105 pass over each stripe region multiple times. In this case, it is also preferable to shift the position of the stripe region depending on the number of times drawing is performed multiple times. It is also preferable to perform multiple drawing, in which drawing is performed on the same pixel multiple times during one stage movement.

[0066] FIG. 22 shows an example of a multibeam irradiation area and a target pixel for drawing in the first embodiment. In FIG. 22, a stripe area 32 is divided into a plurality of mesh areas, for example, based on the beam size of the multibeam 20. Each mesh area corresponds to a target pixel 36 (beam irradiation unit area, irradiation position). The size of the target pixel 36 is not limited to the beam size and may be any size regardless of the beam size. For example, the size may be 1 / n (n is an integer greater than or equal to 1) of the beam size. The example of FIG. 22 shows a case where the target region for drawing on the sample 101 is divided, for example, in the y direction, into a plurality of stripe areas 32, each having a width substantially equal to the size of an irradiation region 34 (a drawing field) that can be irradiated with one irradiation of the multibeam 20. The size of the rectangular irradiation region 34 in the x direction can be defined by the number of beams in the x direction multiplied by the beam pitch in the x direction. The size of the rectangular irradiation region 34 in the y direction can be defined by the number of beams in the y direction multiplied by the beam pitch in the y direction. In the example of FIG. 22, for example, a 24×24 array of multi-beams is shown, but is abbreviated to an 8×8 array of multi-beams. A plurality of pixels 28 (beam drawing positions) that can be irradiated with one shot of the multi-beam 20 are shown within the irradiation area 34. The pitch between adjacent pixels 28 is the inter-beam pitch of each of the multi-beams. A rectangular area surrounded by the size of the inter-beam pitch in the x and y directions constitutes one sub-irradiation area 29 (pitch cell area). In the example of FIG. 22, each sub-irradiation area 29 is shown as being composed of, for example, 4×4 pixels.

[0067] FIG. 23 is a diagram illustrating an example of a multi-beam writing operation in the first embodiment. The example of FIG. 23 shows a case where writing is performed in each sub-irradiation region 29 with four different beams. The example of FIG. 23 also shows a writing operation in which the XY stage 105 continuously moves at a speed of a distance L of 8 beam pitches while writing 1 / 4 of the region in each sub-irradiation region 29 (one of the number of beams used for irradiation). In the writing operation shown in the example of FIG. 23, for example, while the XY stage 105 moves the distance L of 8 beam pitches, the sub-deflector 209 sequentially shifts the irradiation position (pixel 36), and four shots of the multi-beam 20 are performed in a shot cycle T, thereby writing (exposing) four different pixels in the same sub-irradiation region 29. During the writing (exposure) of these four pixels, the main deflector 208 deflects the entire multibeam 20 collectively to prevent the relative position of the irradiation area 34 to the sample 101 from shifting due to the movement of the XY stage 105, thereby allowing the irradiation area 34 to follow the movement of the XY stage 105. In other words, tracking control is performed. After one tracking cycle is completed, tracking is reset and the system returns to the previous tracking start position. Note that since writing of the first pixel row from the right in each sub-irradiation area 29 has been completed, after tracking reset, the sub-deflector 209 first deflects the beam to align (shift) the writing position of the beam so that writing of an unwritten pixel row in each sub-irradiation area 29, for example, the second pixel row from the right, is performed. By repeating this operation during writing of the stripe area 32, the position of the irradiation area 34 of the multibeam 20 sequentially moves as shown in the lower diagram of FIG. 21, and writing is performed.

[0068] As described above, according to the first embodiment, the backflow of the positive ions 21 to the cathode 10, which is generated due to the collision of the electrons after passing through the passage holes 11 of the anode 14, can be suppressed or reduced.

[0069] Although the embodiments have been described above with reference to specific examples, the present invention is not limited to these specific examples.

[0070] Although the description of the device configuration, control method, and other parts not directly necessary for the explanation of the present invention have been omitted, the required device configuration and control method can be appropriately selected and used. For example, the description of the control unit configuration that controls the drawing device 100 has been omitted, but it goes without saying that the required control unit configuration can be appropriately selected and used.

[0071] In addition, all electron guns and electron beam writing apparatuses that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of symbols]

[0072] 7 Electrode substrate 8 Support cylinder 10 cathode 11,17 Passing hole 12 Wehnelt 14 anode 15,19 Opening 16 Limiting Aperture Board 18 Return 20 Multibeam 21 positive ions 22 holes 24 control electrode 25 Passing hole 26 Counter electrode 29 Sub-irradiation area 30 drawing area 32 stripe area 34 Irradiation area 36 pixels 41 Control circuit 59 Heater 62 Accelerating voltage power supply 64 Wehnelt power supply 66 Heater power supply 70 ammeter 100 drawing device 101 Sample 102 Electron Telescope 103 Drawing room 105 XY stage 106 Electron gun chamber 110 Control computer 112 memory 120 High-voltage power supply circuit 130 Deflection control circuit 132,134 DAC amplifier unit 136 Lens control circuit 138 Stage Control Mechanism 139 Stage Position Measuring Instrument 140 Storage device 150 Drawing mechanism 160 Control Circuits 200 electron beam 201 Electron Gun 202 Lighting lens 203 Shaped Aperture Array Substrate 204 Blanking Aperture Array Mechanism 205 Reduction Lens 206 Limiting Aperture Substrate 207 Objective Lens 208 Main deflector 209 Sub deflector 210 Mirror 330 Membrane Region

Claims

1. a cathode that emits an electron beam; an anode electrode having a surface facing the cathode, a first opening formed in the surface to allow the electron beam emitted from the cathode to pass therethrough, and at least one second opening formed on the same surface as the first opening but at a position different from the first opening, the anode electrode being held at a potential relatively positive to the potential of the cathode; a limiting aperture substrate disposed downstream of the anode electrode in the direction of travel of the electron beam, the limiting aperture substrate having a third opening through which the electron beam passes and limiting passage of a portion of the electron beam; a Wehnelt electrode disposed between the cathode and the anode, to which a negative potential relative to the potential of the anode is applied; An electron gun comprising:

2. 2. The electron gun of claim 1, wherein said at least one second opening is larger in size than said first opening.

3. 3. The electron gun according to claim 1, wherein the distance from the center of the first opening to the center of the second opening satisfies a quadratic equation using the distance between the anode electrode and the Wehnelt electrode as a parameter.

4. The distance y from the center of the first opening to the center of the second opening is calculated by the following equation using the distance x between the anode electrode and the Wehnelt electrode as a parameter: <h2 style=";text-align:left;direction:ltr">y=0.037x<h2 style=";text-align:left;direction:ltr"> ２ <h2 style=";text-align:left;direction:ltr"> 15362536566±1536253656 ...

3. The electron gun according to claim 1, wherein the following is satisfied:

5. 3. The electron gun according to claim 1, wherein the at least one second opening comprises a plurality of second openings formed rotationally symmetrically with respect to the center of the first opening.

6. 3. The electron gun according to claim 1, further comprising a convex portion formed so as to extend from the back surface of the anode electrode opposite the surface toward the limiting aperture substrate, and positioned near the outer periphery of at least one of the second openings.

7. a stage on which a sample is placed; a cathode that emits an electron beam; an anode electrode having a surface facing the cathode, a first opening formed in the surface to allow the electron beam emitted from the cathode to pass therethrough, and at least one second opening formed on the same surface as the first opening but at a position different from the first opening, the anode electrode being held at a potential relatively positive to the potential of the cathode; a limiting aperture substrate disposed downstream of the anode electrode in the direction of travel of the electron beam, the limiting aperture substrate having a third opening through which the electron beam passes and limiting passage of a portion of the electron beam; a Wehnelt electrode disposed between the cathode and the anode, to which a negative potential relative to the potential of the anode is applied; an electron gun having an electron optical system that guides the electron beam emitted from the electron gun to the sample; 1. An electron beam lithography apparatus comprising:

8. 8. The electron beam writing apparatus according to claim 7, wherein the at least one second opening is larger in size than the first opening.

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