Multi-charged particle beam irradiation device

Abstract

The present invention suppresses deterioration of beam characteristics and blank characteristics of multi-beams, and stabilizes the beam irradiation positions and dimensions and irradiation amounts. This multi-charged particle beam irradiation device comprises: a plurality of blankers that perform blanking deflection of each of multi-charged particle beams; a stopping aperture member that blocks the beams that are deflected to enter a beam-off state by means of the plurality of blankers; two or more stages of objective lenses that are composed of magnetic field lenses and align the focal points of the multi-charged particle beams onto a substrate to be irradiated; and three or more correction lenses that perform correction of the image-forming state of the multi-charged particle beams on the substrate. The three or more correction lenses include one magnetic field correction lens and two electrostatic correction lenses. The two electrostatic correction lenses are disposed in a lens magnetic field of a final stage objective lens closest to the substrate among the two or more stages of objective lenses.

Description

Multi-charged particle beam irradiation device

[0001] The present invention relates to a multi-charged particle beam irradiation device.

[0002] With the increasing integration density of LSIs, the circuit line width required for semiconductor devices has been getting finer year by year. To form the desired circuit pattern on a semiconductor device, a method is adopted in which a high-precision master pattern formed on quartz is reduced and transferred onto a wafer using a reduction projection exposure apparatus. To produce the high-precision master pattern, a technique called electron beam lithography is used, in which a resist is exposed to light using an electron beam writing apparatus to form a pattern.

[0003] As electron beam lithography systems, development is underway to replace the conventional single-beam lithography systems, which deflect a single beam and irradiate the required location on a sample. By using multiple beams, it is possible to irradiate more beams than with a single electron beam, thereby significantly improving throughput. In a multi-beam lithography system, for example, an electron beam emitted from an electron source is passed through a shaping aperture array member with multiple openings to form multiple beams, blanking control is performed for each beam using a blanking aperture array substrate, and the beam not blocked by the stopping aperture member is reduced in size by an optical system and irradiated onto a sample placed on a movable stage.

[0004] In electron beam lithography systems, the beam for each shot is focused on the sample using an objective lens. Dynamic focus, for example, using an electrostatic lens, is then performed during lithography to dynamically correct the position of the multi-beam array image along the optical axis (image height) to accommodate the unevenness of the sample surface. Here, the optical axis refers to the central axis of the optical system from when the electron beam is emitted until it is irradiated onto the sample. However, dynamic focus can cause rotation and magnification fluctuations in the beam array image on the sample, degrading the lithography position accuracy. Therefore, it is necessary to minimize the rotation and magnification fluctuations of the beam array image, which are dependent on dynamic focus.

[0005] In order to suppress rotation and magnification fluctuation of the beam array image that depend on dynamic focus, a multi-beam lithography device has been proposed in which three electrostatic correction lenses are provided and at least one electrostatic correction lens is positioned in the lens magnetic field of each stage of two stages of objective lenses (see, for example, Patent Document 1).

[0006] For example, a first electrostatic correction lens is arranged in the lens magnetic field of an upper objective lens located upstream in the direction of beam propagation, and a second electrostatic correction lens and a third electrostatic correction lens are arranged in the lens magnetic field of a lower objective lens (final objective lens) located downstream in the direction of beam propagation.

[0007] In a lithography system, the optical axis of the multi-beams is adjusted to align with the central axis of the objective lens to reduce distortion of the beam array image. If there is a misalignment between the central axis of the objective lens and the central axis of the electrostatic correction lens due to manufacturing errors, the beam will follow a trajectory that deviates from the central axis of the electrostatic correction lens, and when a voltage is applied to the electrostatic correction lens to operate it, the beam trajectory will be bent.

[0008] When the beam trajectory is bent by the first electrostatic correction lens within the lens magnetic field of the upper objective lens, the beam travels a long distance from its bent trajectory to the final objective lens, and is incident on a position away from the center of the final objective lens. This causes a problem in that the characteristics of the multi-beam (distortion of the beam array shape and beam aberration) deteriorate due to the influence of objective lens aberration, reducing the positional accuracy and dimensional accuracy of the irradiated beam.

[0009] Furthermore, in a configuration in which a stopping aperture member is positioned in accordance with a crossover formed near the magnetic pole of the final stage objective lens (see, for example, Patent Document 2), when the beam trajectory is bent by the operation of the first electrostatic correction lens, the beam position at the stopping aperture member changes, and the blanking characteristics deteriorate, making the beam irradiation amount unstable, such that the desired current attenuation rate cannot be obtained, the beam cannot be blanked (shielded), or the beam is always blanked, resulting in a problem of reduced dimensional accuracy of the drawn pattern.

[0010] Increasing the inner diameter of the electrostatic correction lens can reduce the effects of misalignment with the central axis (optical axis) of the objective lens, but because the electrostatic correction lens must be placed in a vacuum, complex structures such as a vacuum partition, vacuum seal, external wiring leads, and insulator supports in vacuum are required outside the electrostatic correction lens electrodes, which places significant constraints on increasing the inner diameter. Furthermore, most of the region where the lens magnetic field of the objective lens where the electrostatic correction lens is placed exists is a narrow space surrounded by small-diameter magnetic poles, so the inner diameter of the electrostatic correction lens cannot be increased.

[0011] JP-A-2013-197289 Patent No. 4995261 JP-A 8-195345 JP-A 2006-294962 JP-A 4-032143

[0012] The present invention has been made in consideration of the above-mentioned conventional problems, and has an object to provide a multi-charged particle beam irradiation device that can suppress deterioration of the beam characteristics and blank characteristics of multi-beams and stabilize the beam irradiation position, dimensions, and irradiation amount.

[0013] A multi-charged particle beam irradiation device according to one aspect of the present invention comprises a plurality of blankers that blank and deflect each beam of a multi-charged particle beam, a stopping aperture member that blocks the beams deflected by the plurality of blankers to be in a beam-off state, two or more stages of objective lenses made of magnetic lenses that focus the multi-charged particle beam on a substrate to be irradiated, and three or more correction lenses that correct the imaging state of the multi-charged particle beam on the substrate, wherein the three or more correction lenses include one magnetic correction lens and two electrostatic correction lenses, and the two electrostatic correction lenses are arranged within the lens magnetic field of the final stage objective lens that is closest to the substrate among the two or more stages of objective lenses.

[0014] According to the present invention, it is possible to suppress deterioration of the beam characteristics and blank characteristics of a multi-beam, and to stabilize the beam irradiation position, dimensions, and irradiation amount.

[0015] Fig. 1 is a schematic diagram of a multi-charged particle beam drawing apparatus according to a first embodiment of the present invention; Fig. 2 is a diagram explaining the locations of a magnetic field correction lens and a stopping aperture member; Fig. 3 is a schematic diagram of a shaping aperture array substrate; Fig. 4 is a diagram explaining the locations of a magnetic field correction lens and a stopping aperture member according to a second embodiment; Fig. 5 is a diagram explaining the locations of a magnetic field correction lens and a stopping aperture member according to a third embodiment; Fig. 6 is a diagram explaining the locations of a magnetic field correction lens and a stopping aperture member according to a fourth embodiment; Fig. 7 is a diagram explaining the locations of a magnetic field correction lens and a stopping aperture member according to a fifth embodiment.

[0016] In the following embodiments, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and a beam using charged particles such as an ion beam may also be used. Furthermore, in the embodiments, a multi-beam lithography system using multiple electron beams will be described as an example of a multi-charged particle beam irradiation system. However, the multi-charged particle beam irradiation system is not limited to a multi-beam lithography system, and the present embodiments can also be applied to a multi-beam inspection system.

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] 1 is a schematic diagram of a multi-charged particle beam lithography apparatus according to a first embodiment of the present invention. This lithography apparatus includes a lithography unit W that irradiates an electron beam onto a substrate 24 to be lithographed, thereby lithographing a desired pattern, and a control unit C that controls the operation of the lithography unit W.

[0019] The imaging unit W has an electron optical column 2 and an imaging chamber 20. Inside the electron optical column 2, an electron source 4, an illumination lens 6, a shaping aperture array substrate 8, a blanking aperture array substrate 10, a reduction lens 12, a magnetic field correction lens 40, a stopping aperture member 14, two-stage objective lenses 16 and 17, and two electrostatic correction lenses 66 and 67 are provided.

[0020] The illumination lens 6 is disposed between the electron source 4 and the shaping aperture array substrate 8. The illumination lens 6 may be a magnetic lens or an electrostatic lens. The reduction lens 12 is disposed between the blanking aperture array substrate 10 and the objective lens 16. The reduction lens 12 may be a magnetic lens or an electrostatic lens. The objective lenses 16 and 17 are magnetic lenses.

[0021] Of the multiple objective lenses provided in the drawing apparatus, the objective lens 17 is the one arranged most downstream in the beam traveling direction. The objective lens 16 is arranged upstream of the objective lens 17 in the beam traveling direction. Due to this positional relationship, the objective lens 16 is sometimes called the upper objective lens, and the objective lens 17 is sometimes called the lower objective lens. Also, the objective lens 17 is sometimes called the final objective lens.

[0022] As shown in FIGS. 1 and 2 , the magnetic field correction lens 40 is disposed downstream of the object plane (intermediate image IS1, described later) of the final-stage objective lens 17, near the midpoint between the object plane of the objective lens 17 and the magnetic pole. The magnetic field correction lens 40 is also disposed outside the lens magnetic fields of the objective lenses 16 and 17. The magnetic field (axial magnetic flux density) of a magnetic lens attenuates with increasing distance from the lens magnetic pole. The axial magnetic flux density is typically maximized near the midpoint between a pair of magnetic poles (two magnetic poles) of the magnetic lens, i.e., on the optical axis near the center of the gap of the magnetic lens. Empirically, a region where the axial magnetic flux density is greater than, for example, 1 / 10 of the maximum value, or a region where the magnetic flux density is minimal, is considered to be "inside the magnetic field," while other regions are considered to be "outside the magnetic field."

[0023] 2, the objective lenses 16 and 17, which are magnetic lenses, have coils 16a and 17a and yokes 16b and 17b that house the coils 16a and 17a. The yokes 16b and 17b are made of a material with high magnetic permeability, such as iron, and pole pieces 16c1, 16c2, 17c1, and 17c2 of the yokes 16b and 17b form gaps 16d and 17d. In this embodiment, the ends of the pole pieces 16c1, 16c2, 17c1, and 17c2 in the optical axis direction that form the gaps 16d and 17d of the magnetic lenses (the lower ends of the pole pieces 16c1 and 17c1 on the upstream side in the beam propagation direction and the upper ends of the pole pieces 16c2 and 17c2 on the downstream side) are referred to as magnetic poles.

[0024] In addition, in order to reduce aberrations and distortions, a single stage objective lens may be composed of two or more adjacent magnetic lenses. In such cases, even if there is a location between the adjacent magnetic lenses that make up a single stage objective lens where the magnetic flux density is 1 / 10 or less or is extremely small, this is not considered to be a boundary between inside and outside the lens magnetic field of the objective lens, but is considered to be "inside the magnetic field."

[0025] The magnetic field correction lens 40 generates a small rotationally symmetric magnetic field to correct the imaging state. For example, the magnetic field correction lens 40 is a circular coil or solenoid coil with the beam optical axis as its central axis, through which a current for correction is passed. The coil may be surrounded by a magnetic material such as ferrite. Unlike the electrostatic correction lenses 66 and 67, the magnetic field correction lens 40 is usually placed outside the vacuum, so it does not require complex structures such as a vacuum seal, external wiring leads, or insulator support in the vacuum.

[0026] The electrostatic correction lenses 66 and 67 are arranged within the magnetic field of the objective lens 17 which is a magnetic lens (i.e., within the magnetic field).

[0027] The electrostatic correction lenses 66 and 67 generate a small rotationally symmetric electric field to correct the imaging state of the multi-beam. For example, the electrostatic correction lenses 66 and 67 are configured with cylindrical electrodes, and a voltage for correction is applied to them. Cylindrical earth electrodes may be placed before and after the electrode to which the voltage is applied.

[0028] In addition, a configuration in which a cylindrical or ring-shaped electrode is divided (for example, divided like an octapole deflector) and voltages that generate a focusing electric field (rotationally symmetric electric field), a deflecting electric field, a multipole electric field, etc. are added and applied to these electrode groups, thereby combining the functions of a lens, deflector, multipole, etc., also generates an electric field with a lens effect, and therefore such an electrode group is also included in a single electrostatic correction lens.

[0029] An XY stage 22 is arranged in the pattern writing chamber 20. A substrate 24 to be patterned is placed on the XY stage 22. The substrate 24 to be patterned is, for example, a mask blank or a semiconductor substrate (silicon wafer).

[0030] An electron beam 30 emitted from the electron source 4 is illuminated almost perpendicularly by an illumination lens 6 onto a shaping aperture array substrate 8. FIG. 3 is a conceptual diagram showing the configuration of the shaping aperture array substrate 8. In the shaping aperture array substrate 8, openings 80 are formed in a matrix of m columns (y direction) x n columns (x direction) (m, n≧2) at a predetermined arrangement pitch. For example, 512 columns x 512 columns of openings 80 are formed. Each opening 80 is formed as a rectangle of the same size and shape. Each opening 80 may also be a circle of the same diameter.

[0031] The electron beam 30 illuminates an area that includes all of the openings 80 of the shaping aperture array substrate 8. Portions of the electron beam 30 pass through each of the plurality of openings 80, thereby forming a multi-beam 30M as shown in FIG.

[0032] Through holes are formed in the blanking aperture array substrate 10 in alignment with the positions of the openings 80 in the shaping aperture array substrate 8, and blankers consisting of a pair of electrodes are disposed in each through hole. The multi-beams 30M passing through each through hole are independently deflected by voltages applied to the blankers. Blanking control is performed on each beam by this deflection. In this way, blanking deflection is performed by the blanking aperture array substrate 10 on each beam of the multi-beams 30M that have passed through the multiple openings 80 in the shaping aperture array substrate 8.

[0033] The multi-beams 30M that have passed through the blanking aperture array substrate 10 are reduced in beam size and arrangement pitch by the reduction lens 12, and proceed so as to form a crossover CO1 slightly upstream of the objective lens 16. The upper-stage objective lens 16 acts on the multi-beams 30M that have formed the crossover CO1, forming a reduced intermediate image IS1 of the multiple openings 80 in the shaping aperture array substrate 8, and forming a crossover CO2 between the intermediate image IS1 and the substrate 24. The imaging plane of the intermediate image IS1 corresponds to the object plane of the final-stage objective lens 17.

[0034] The stopping aperture member 14 is disposed near the magnetic pole of the objective lens 17 so that the center of the opening formed in the stopping aperture member 14 substantially coincides with the crossover CO2. Here, the electron beam deflected by the blanker of the blanking aperture array substrate 10 has its trajectory displaced and moves away from the opening of the stopping aperture member 14, and is blocked by the stopping aperture member 14. On the other hand, the electron beam not deflected by the blanker of the blanking aperture array substrate 10 passes through the opening of the stopping aperture member 14.

[0035] In this way, the stopping aperture member 14 blocks each electron beam deflected to a beam-off state by the blanker of the blanking aperture array substrate 10. Then, the beam that passes through the stopping aperture member 14 from when the beam is turned on until when the beam is turned off becomes the electron beam for one shot.

[0036] The lower objective lens 17 reduces the intermediate image IS1 and forms an image (beam array image) IS2 of the plurality of openings 80 in the shaping aperture array substrate 8 at a desired reduction ratio on the surface of the substrate 24. In this way, the objective lenses 16 and 17 focus the electron beam on the top (surface) of the substrate 24. Note that the reduction ratio is the reciprocal of the magnification, and is, for example, the ratio between the size (or pitch) of the electron beam formed by portions of the electron beam 30 passing through each of the plurality of openings 80 in the shaping aperture array substrate 8 and the size (or pitch) of the image formed on the surface of the substrate 24.

[0037] By using two stages of objective lenses, a high reduction ratio (for example, a magnification of about 1 / 200) can be achieved, and a distance (working distance) can be secured between the underside of the final stage lens (objective lens 17) and the substrate 24 so that the substrate 24 can move.

[0038] The electrostatic correction lenses 66, 67 can be operated with respect to the surface of the substrate 24 in either a positive voltage range, a negative voltage range, or a voltage range including both polarities.

[0039] The electron beams (the entire multi-beam) that pass through the stopping aperture member 14 are deflected in the same direction by a deflector (not shown) and irradiated onto the substrate 24. The deflector (not shown) may be located downstream of the blanking aperture array substrate 10, but locating it downstream of the upper objective lens 16 has the advantage of reducing distortion and aberration. When the XY stage 22 moves continuously, the beam irradiation position is deflected to follow the movement of the XY stage 22. Furthermore, as the XY stage 22 moves, the drawing position changes each time, and the height of the surface of the substrate 24 onto which the multi-beam is irradiated changes. Therefore, the magnetic field correction lens 40 and electrostatic correction lenses 66 and 67 dynamically correct the defocusing of the multi-beam during drawing (dynamic focus).

[0040] The multiple beams irradiated at one time are ideally arranged at a pitch obtained by dividing the arrangement pitch of the plurality of openings 80 in the shaping aperture array substrate 8 by the desired reduction ratio (i.e., multiplying by the magnification). This drawing device performs drawing operations using a raster scan method in which shot beams are continuously irradiated in order, and when drawing a desired pattern, the beams required for the pattern are turned on by blanking control.

[0041] The control unit C has a control computer 32 and a control circuit 34. The control computer 32 performs multiple stages of data conversion processing on the drawing data to generate shot data specific to the device and outputs it to the control circuit 34. The shot data defines the dose and irradiation position coordinates of each shot. The control circuit 34 calculates the irradiation time by dividing the dose of each shot by the current density, and when the corresponding shot is performed, applies a deflection voltage to the corresponding blanker on the blanking aperture array substrate 10 so that the beam is turned on for the calculated irradiation time.

[0042] The control computer 32 holds data on a relational expression that links the excitation amounts of the magnetic correction lens 40 and the electrostatic correction lenses 66 and 67, which will be described later, and calculates the excitation amount of each correction lens using this relational expression. The control circuit 34 applies the excitation amount calculated from the relational expression to the magnetic correction lens 40 and the electrostatic correction lenses 66 and 67 to operate them. Note that the excitation amount is an excitation current for the magnetic correction lenses, and an applied voltage for the electrostatic correction lenses.

[0043] The magnetic correction lens has the effect of rotating the beam image (rotation effect), and this effect occurs regardless of whether the magnetic correction lens is located inside or outside the magnetic field of the objective lens in the optical axis direction. The image rotation is a simple addition of the rotation effect of the objective lens magnetic field and the rotation effect of the magnetic correction lens magnetic field, and even if the two magnetic fields overlap, no synergistic effect (a rotation effect proportional to the product of the two magnetic fields) occurs. Note that in this embodiment, when the reduction lens 12 is a magnetic lens, the rotation effect of the reduction lens is also added to the image rotation.

[0044] When a magnetic correction lens is placed within the lens's magnetic field, the sensitivity of image height correction increases, and the magnification correction effect also increases. Because the focusing force of the lens's magnetic field is proportional to the square of the axial magnetic flux density, overlapping of the magnetic fields of the objective lens and the magnetic correction lens in the optical axis direction produces a synergistic effect (a focusing effect proportional to the product of the two magnetic fields), resulting in a large change in focusing force in response to a small change in the magnetic field of the correction lens. On the other hand, when the magnetic correction lens is placed outside the lens's magnetic field, the change in focusing force becomes very small, and the sensitivity of image height and magnification correction decreases.

[0045] Therefore, the magnetic field correction lens 40 arranged outside the lens magnetic field as in this embodiment has the characteristics of low correction sensitivity for image height and magnification, and high rotation correction sensitivity.

[0046] An electrostatic lens placed in the magnetic field of an objective lens (magnetic lens) changes the energy of the beam within the electrostatic lens, thereby changing the focusing effect on the beam from the magnetic lens, thereby changing the imaging height. This change in focusing effect also causes a change in magnification. Rotation does not normally occur with an electrostatic lens alone, but when placed in the lens magnetic field, the rotation also changes due to the energy change through the magnetic lens effect. Here, because the magnetic field generated by the objective lens to focus the beam is extremely strong, even a small change in energy due to a small change in the voltage applied to the electrostatic lens can significantly change the focusing effect and rotation effect of the entire lens magnetic field. Therefore, the electrostatic correction lenses 66 and 67 placed in the lens magnetic field of the final-stage objective lens 17 have high correction sensitivity for imaging height, magnification, and rotation.

[0047] A detailed examination of the correction sensitivities of the electrostatic correction lenses 66 and 67 within the objective lens magnetic field reveals that the correction sensitivities depend on the objective lens magnetic field strength (magnetic flux density) and the beam trajectory value (distance from the optical axis) at the position of the electrostatic correction lens. Furthermore, the image height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity have mutually different dependencies. Even within the same final-stage objective lens magnetic field, the two electrostatic correction lenses 66 and 67 are positioned at different positions along the beam optical axis, and the magnetic field strength and trajectory values ​​at each position are different, so the ratio of the correction sensitivities of the electrostatic correction lenses 66 and 67 (the ratio of the image height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity) differs.

[0048] As described above, the magnetic correction lens 40 and the electrostatic correction lenses 66 and 67 have different correction characteristics (different ratios of image height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity). Therefore, by controlling the excitation amounts of these three correction lenses (applied voltage for the electrostatic correction lens and excitation current for the magnetic correction lens) in conjunction with an appropriate relationship, the following image state corrections can be made: - Changing the image height in response to variations in the substrate surface height, without changing the magnification or rotation. - Changing the magnification, without rotation or changing the image height, while keeping the substrate surface height constant. - Changing the rotation, without changing the image height or magnification, while keeping the substrate surface height constant. Of the three types of image state corrections described above, the first type is used for focus correction (dynamic focus) performed during writing to accommodate unevenness on the sample surface. The second type can be used for fine adjustment of magnification, and the third type can be used for fine adjustment of rotation.

[0049] The relational expression for the excitation amount linkage in correcting the imaging state differs for each of the three adjustment patterns. The excitation amount can be adjusted with sufficient precision if the relational expression is a polynomial of first or higher order for the adjustment amounts (imaging height, magnification, and rotation). The coefficients of the polynomial are determined by trajectory simulation. The coefficients may also be calculated based on the dependence of the imaging height, magnification, and rotation on the excitation amount, which are actually measured.

[0050] As described above, the magnetic field correction lens 40 can be placed outside of a vacuum and can have a larger diameter than the electrostatic correction lenses 66 and 67, so the effect of bending the beam trajectory is reduced even if the beam follows a trajectory that deviates from the central axis of the magnetic field correction lens 40. This stabilizes the beam position at the stopping aperture member 14, making it possible to suppress deterioration of the blank characteristics.

[0051] Since the magnetic field correction lens 40 is positioned near the midpoint between the object surface and the magnetic pole of the final stage objective lens, the distance to the final stage objective lens is shorter than that of a conventional electrostatic correction lens positioned in the lens magnetic field of an upper stage objective lens, and the effect of axial misalignment on orbital deviation in the final stage objective lens can be reduced.

[0052] The electrostatic correction lenses 66, 67 are positioned at approximately the same position (height) as the magnetic pole of the final stage objective lens, and the distance in the optical axis direction to the magnetic pole is extremely short, so even if a misalignment occurs between the central axis of the electrostatic correction lenses 66, 67 and the central axis of the final stage objective lens, causing the beam trajectory to bend, the beam will be incident near the center of the final stage objective lens.

[0053] This makes it possible to stabilize the beam irradiation position and dimensions by suppressing deterioration of the characteristics of the multi-beams irradiated onto the substrate 24 (distortion of the beam array shape and beam aberration). Because the beam position at the stopping aperture member 14 hardly changes, the blank characteristics do not deteriorate and the beam irradiation amount is stabilized.

[0054] In the first embodiment, since there is ample space for the magnetic field correction lens 40 placed outside the vacuum, a movement mechanism may be provided to finely move the magnetic field correction lens 40 in the X and Y directions (horizontal direction). By using the movement mechanism to finely adjust the magnetic field correction lens 40, the axial misalignment between the central axis of the magnetic field correction lens 40 and the beam axis can be reduced.

[0055] In the first embodiment described above, the electrostatic correction lenses 66 and 67 are placed in the objective lens magnetic field, which increases the correction sensitivity, reduces the voltage required for correction, and reduces the burden (technical and cost-wise) on the driving circuit of the electrostatic correction lens.

[0056] In contrast, for example, if one correction electrostatic lens is moved upstream and placed outside the objective lens's magnetic field, it is possible to correct the imaging state by linking the excitation amount of the electrostatic correction lens, but the voltage (absolute value of the applied voltage) applied to the electrostatic correction lens outside the objective lens's magnetic field will be higher. For example, to correct the imaging height by 5 μm in the above embodiment, a maximum voltage of approximately 120 V is applied, but if the electrostatic correction lens is placed outside the objective lens's magnetic field, a voltage one order of magnitude higher, approximately 1100 V, will need to be applied. Thus, placing the electrostatic correction lens outside the objective lens's magnetic field increases the applied voltage and increases the cost of the drive circuit.

[0057] Second Embodiment In the first embodiment, the crossover CO2 is formed upstream of the electrostatic correction lenses 66 and 67. However, as shown in Fig. 4, the crossover CO2 may be formed at a height between the electrostatic correction lenses 66 and 67. In this case, the stopping aperture member 14 is disposed between the electrostatic correction lenses 66 and 67 in accordance with the height of the crossover CO2.

[0058] Even with this configuration, it is possible to suppress deterioration of the beam characteristics and blank characteristics of the multi-beams, similar to the first embodiment.

[0059] [Third Embodiment] In the first embodiment, the stopping aperture member 14 is disposed at the height of the crossover CO2, but as shown in Fig. 5, the stopping aperture member 14 may be disposed at the height of the crossover CO1 near the magnetic pole of the upstream objective lens 16. The crossover CO1 is formed upstream of the object plane of the final-stage objective lens 17 in the beam traveling direction.

[0060] Even with this configuration, it is possible to suppress deterioration of the multi-beam characteristics, as in the first embodiment. Furthermore, since the stopping aperture member 14 is located upstream of the correction lens, deterioration of the blank characteristics due to axial misalignment does not occur.

[0061] [Fourth embodiment] In the first embodiment, the magnetic field correction lens 40 is disposed outside the lens magnetic field of the objective lenses 16 and 17. However, as shown in FIG. 6, the magnetic field correction lens 40 may be moved downstream and disposed within the lens magnetic field of the objective lens 17.

[0062] The magnetic field correction lens 40 is disposed upstream of the magnetic pole of the objective lens 17, but is disposed in an area where the axial magnetic flux density is greater than, for example, 1 / 10 of the maximum value of the objective lens 17.

[0063] The effect of the magnetic field correction lens in rotating the beam image (rotation effect) provides high sensitivity regardless of whether the magnetic field correction lens is positioned in the optical axis direction inside or outside the magnetic field of the objective lens. Furthermore, a magnetic field correction lens placed in the magnetic field of the objective lens has a greater lens effect (focusing effect), resulting in high image height correction sensitivity and magnification correction sensitivity. Thus, a magnetic field correction lens placed in the lens magnetic field of the objective lens has high focus and magnification correction sensitivity, and extremely high rotation correction sensitivity.

[0064] The magnetic field correction lens 40 and the electrostatic correction lenses 66, 67 differ in objective lens magnetic field strength and beam trajectory value at the positions where they are arranged, and further differ in that one is a magnetic type and the other is an electrostatic type, so the ratios of correction sensitivities (ratios of imaging height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity) differ between the magnetic field correction lens 40 and the electrostatic correction lenses 66, 67. Therefore, by controlling the excitation amounts of the correction lenses, each of which has different correction characteristics, in conjunction with each other based on a relational expression, it is possible to appropriately adjust the imaging height, magnification, and rotation of the beam array image IS2.

[0065] [Fifth Embodiment] In the first embodiment described above, the magnetic field correction lens 40 is configured to be located downstream of the object plane (intermediate image plane) of the objective lens 17, but the position of the magnetic field correction lens 40 is not limited to this, and it may be located downstream of the blanking aperture array substrate 10.

[0066] 7, the magnetic field correction lens 40 may be arranged upstream of the magnetic pole of the upper-stage objective lens 16 and outside the lens magnetic field of the objective lens 16. In this configuration, the distance to the final-stage objective lens is longer than in the first embodiment, but the magnetic field correction lens 40 can be arranged outside of a vacuum and its diameter can be increased, so that even if the beam follows an orbit deviating from the central axis of the magnetic field correction lens 40, the effect of bending the beam orbit is reduced, and deterioration of the beam characteristics and blank characteristics of the multi-beam can be suppressed.

[0067] In the explanation so far, the electrostatic correction lenses 66 and 67 can operate in a positive voltage range, a negative voltage range, or a voltage range including both polarities relative to the surface of the substrate 24. However, when operating in the positive voltage range, if the voltage of the upstream electrostatic correction lens 66 is relatively lower than the voltage of the downstream electrostatic correction lens 67, secondary electrons from the substrate 24 may accumulate near the boundary between the two electrostatic correction lenses, and the accumulated secondary electrons may cause beam position instability. However, such instability does not necessarily become a problem; it may not become a problem depending on the magnetic field distribution of the objective lens, the inner diameter and positional relationship of the focus correction lens, or the required precision. Furthermore, if the electrostatic correction lenses 66 and 67 are operated in the negative voltage range relative to the surface of the substrate 24, the amount of secondary electrons generated on the substrate 24 that enter the electrostatic correction lenses 66 and 67 can be significantly reduced, so the aforementioned beam position instability does not occur and does not become a problem.

[0068] In the imaging device shown so far, a configuration using three correction lenses has been described, but the number of correction lenses used to correct the imaging state is not limited to three, and may be four or more.

[0069] Furthermore, although the imaging device shown so far has been described as using two stages of objective lenses, it may also be possible to use three or more stages of objective lenses.

[0070] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the effects of the invention. This application is based on Japanese Patent Application No. 2024-071661 filed on April 25, 2024, the entire contents of which are incorporated by reference.

[0071] 2 electron optical column 4 electron source 6 illumination lens 8 shaping aperture array substrate 10 blanking aperture array substrate 12 reduction lens 14 stopping aperture member 16, 17 objective lens 20 drawing chamber 22 XY stage 24 substrate 40 magnetic field correction lens 66, 67 electrostatic correction lens

Claims

1. A multi-charged particle beam irradiation device comprising: a plurality of blankers that perform blanking deflection on each beam of a multi-charged particle beam; a stopping aperture member that blocks the beams deflected by the plurality of blankers to be in a beam-off state; two or more stages of objective lenses consisting of magnetic lenses that focus the multi-charged particle beam on a substrate to be irradiated; and three or more correction lenses that correct the imaging state of the multi-charged particle beam on the substrate, wherein the three or more correction lenses include one magnetic correction lens and two electrostatic correction lenses, and the two electrostatic correction lenses are positioned within the lens magnetic field of the final stage objective lens of the two or more stages of objective lenses that is closest to the substrate.

2. A multi-charged particle beam irradiation device according to claim 1, wherein the stopping aperture member is arranged corresponding to the position of a crossover formed between the object plane of the final stage objective lens and the substrate.

3. A multi-charged particle beam irradiation device as described in claim 1, wherein the stopping aperture member is positioned corresponding to a crossover position formed upstream of the object plane of the final stage objective lens in the beam traveling direction.

4. A multi-charged particle beam irradiation device according to claim 1, wherein the magnetic field correction lens is disposed between the object surface of the final stage objective lens and a magnetic pole.

5. A multi-charged particle beam irradiation device according to claim 4, wherein the magnetic field correction lens is arranged outside the lens magnetic fields of the two or more stages of objective lenses.

6. The multi-charged particle beam irradiation device according to claim 4, wherein the magnetic field correction lens is disposed within the lens magnetic field of the final stage objective lens.

7. A multi-charged particle beam irradiation system according to claim 1, wherein the imaging state of the multi-charged particle beams is corrected by setting the mutual relationship of the excitation amounts of the three or more correction lenses.

8. A multi-charged particle beam irradiation system according to claim 7, wherein the correction of the imaging state is a correction that changes the imaging height without changing the magnification or without rotating the beam.

9. A multi-charged particle beam irradiation system according to claim 7, wherein the correction of the imaging state is a correction that changes the magnification without rotation and without changing the imaging height.

10. A multi-charged particle beam irradiation system according to claim 7, wherein the correction of the imaging state is a correction that changes the rotation while keeping the imaging height and magnification constant.

11. A multi-charged particle beam irradiation device according to claim 2, wherein the stopping aperture member is disposed corresponding to the position of a crossover formed between the two electrostatic correction lenses.

12. A multi-charged particle beam irradiation device as described in claim 1, wherein the magnetic field correction lens is arranged upstream in the beam traveling direction from the magnetic pole of an upper-stage objective lens, which is arranged upstream in the beam traveling direction from the final-stage objective lens among the two or more stages of objective lenses, and outside the lens magnetic field of the upper-stage objective lens.

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