Multi-charged particle beam irradiation device

Abstract

To suppress the degradation of the beam characteristics and shielding characteristics of multiple beams, thereby stabilizing the beam irradiation position or size and irradiation amount. A multi-charged particle beam irradiation device includes: a plurality of shielding devices that shield and deflect each beam of the multiple charged particle beams; a stop aperture member that shields the beams that have been deflected by the aforementioned plurality of shielding devices to a beam-off state; two or more object lenses, formed of magnetic field lenses, that align the focal points of the aforementioned multiple charged particle beams onto a substrate of the irradiated object; and three or more correction lenses that correct the imaging state of the aforementioned multiple charged particle beams on the aforementioned substrate. The aforementioned three or more correction lenses include one magnetic field correction lens and two electrostatic correction lenses. The aforementioned two electrostatic correction lenses are disposed within the lens magnetic field of the final object lens closest to the aforementioned substrate among the aforementioned two or more object lenses.

Description

[Technical Field]

[0001] This invention relates to a multi-charged particle beam irradiation device. [Previous Technology]

[0002] With the increasing integration of LSIs, the required linewidths for semiconductor devices are becoming smaller year by year. In order to form the desired circuit pattern on semiconductor devices, the following method is used: a high-precision original pattern formed on quartz is reduced and transferred onto the wafer using a reduction projection exposure device. The fabrication of the high-precision original pattern uses electron beam lithography, a technique that forms the pattern by exposing the resist using an electron beam lithography device.

[0003] As an electron beam mapping apparatus, the development of multi-beam mapping apparatuses is underway to replace the single-beam mapping apparatuses that previously deflected a single beam to irradiate a necessary portion of the sample. By using multiple beams, more beams can be irradiated compared to single-beam mapping, thus significantly increasing output. In multi-beam mapping apparatuses, for example, an electron beam emitted from an electron source is passed through a shaped aperture array member having multiple openings to form multiple beams. Then, the shielding of each beam is controlled by a shielding aperture array substrate. The beams not shielded by the shielding aperture member are reduced by an optical system and irradiated onto a sample placed on a movable platform.

[0004] In an electron beam mapping apparatus, the focal points of each fired beam are focused onto the sample using an objective lens. Furthermore, an electrostatic lens, for example, is used to dynamically correct the focus during mapping (dynamic focusing) to accommodate the unevenness of the sample surface and adjust the position (imaging height) of the optical axis of the multi-beam array image. Here, the optical axis refers to the central axis of the optical system from which the electron beam is emitted until it illuminates the sample. However, if dynamic focusing is performed, the beam array image on the sample will rotate or its magnification will change, leading to a deterioration in the accuracy of the mapping position. Therefore, it is necessary to minimize the rotation and magnification changes of the beam array image related to dynamic focusing.

[0005] In order to suppress the rotation and magnification variation of the beam array image related to dynamic focusing, a multi-beam drawing device has been proposed, which is designed to set three electrostatic correction lenses and to arrange at least one electrostatic correction lens in the lens magnetic field of each segment of the two object lenses (see, for example, Patent Document 1).

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

[0007] In the drawing apparatus, in order to reduce the distortion of the beam array image, the optical axes of the multiple beams are adjusted to align with the central axis of the objective lens. When the central axis of the objective lens deviates from the central axis of the electrostatic correction lens due to manufacturing errors, the beam will pass through a track that deviates from the central axis of the electrostatic correction lens. If a voltage is applied to the electrostatic correction lens to activate it, the beam track will be bent.

[0008] When the beam track is bent by the first electrostatic correction lens in the lens magnetic field of the upper objective lens, the beam will travel a long distance from the point where the track is bent to the final objective lens. Therefore, it will be incident at a position far away from the center of the final objective lens. Due to the influence of the objective lens aberration, the characteristics of the multi-beam (distortion of the beam array shape or beam aberration) will be degraded, resulting in problems such as reduced positional accuracy or dimensional accuracy of the emitted beam.

[0009] Furthermore, in a configuration where the stop aperture member is arranged at the crossover point near the magnetic pole of the final segment object lens (for example, see Patent Document 2), if the trajectory of the beam is bent due to the operation of the first electrostatic correction lens, the beam position at the stop aperture member will change, the shielding characteristics will deteriorate, and the beam irradiation amount will be unstable. For example, the desired current attenuation rate cannot be obtained, the beam cannot be shielded, or the beam is always shielded. As a result, problems such as reduced dimensional accuracy of the drawn pattern will occur.

[0010] Increasing the inner diameter of the electrostatic correction lens can reduce the influence of the deviation from the central axis (optical axis) of the objective lens. However, the electrostatic correction lens must be placed in a vacuum. Therefore, a complex structure is required on the outside of the electrostatic correction lens electrodes, including a vacuum partition, vacuum seal, wiring leading out of the vacuum, and support from an insulator in the vacuum. This greatly limits the possibility of increasing the inner diameter. Furthermore, the objective lens used to mount the electrostatic correction lens has a lens magnetic field that exists mostly in a narrow space surrounded by small-diameter magnetic poles, making it impossible to increase the inner diameter of the electrostatic correction lens. (Prior art documents, patent documents)

[0011] Patent Document 1: Japanese Patent Application Publication No. 2013-197289; Patent Document 2: Japanese Patent Application Publication No. 4995261; Patent Document 3: Japanese Patent Application Publication No. H08-195345; Patent Document 4: Japanese Patent Application Publication No. 2006-294962; Patent Document 5: Japanese Patent Application Publication No. H04-032143 [Summary of the Invention]

[0012] Problem to be Solved by the Invention This invention was made in view of the aforementioned problems, and the problem to be solved is to provide a multi-charged particle beam irradiation device that suppresses the deterioration of the beam characteristics and shielding characteristics of multiple beams, and is able to stabilize the beam irradiation position or size and irradiation amount. Technical Means for Solving the Problem

[0013] A multi-charged particle beam irradiation apparatus according to one aspect of the present invention comprises: a plurality of shielding devices for shielding and deflecting each beam of the multi-charged particle beam; a stop aperture member for shielding the beams that have been deflected by the plurality of shielding devices to a beam-closed state; two or more object lenses, formed of magnetic field lenses, for aligning the focal point of the multi-charged particle beams onto a substrate of the irradiated object; and three or more correction lenses for correcting the imaging 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 being disposed within the lens magnetic field of the final object lens closest to the substrate among the two or more object lenses. Effects of the Invention

[0014] According to the present invention, the deterioration of the beam characteristics and shielding characteristics of multiple beams can be suppressed, thereby stabilizing the beam irradiation position or size and irradiation amount.

Implementation Method

[0016] Hereinafter, in the embodiments, an example configuration using an electron beam as a charged particle beam will be described. However, the charged particle beam is not limited to an electron beam, and may also be a beam of charged particles using an ion beam or the like. Furthermore, in the embodiments, as an example of a multi-charged particle beam irradiation apparatus, a multi-beam drawing apparatus using multiple electron beams will be described. However, the multi-charged particle beam irradiation apparatus is not limited to a multi-beam drawing apparatus, and this embodiment can also be applied to a multi-beam inspection apparatus.

[0017] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0018] [First Embodiment] FIG1 is a schematic diagram of a multi-charged particle beam drawing apparatus according to a first embodiment of the present invention. This drawing apparatus includes a drawing section W that irradiates an electron beam onto a substrate 24 to be drawn to draw a desired pattern, and a control section C that controls the operation of the drawing section W.

[0019] The drawing unit W includes an electron optical lens barrel 2 and a drawing chamber 20. Inside the electron optical lens barrel 2, there is an electron source 4, an illumination lens 6, a forming aperture array substrate 8, a blocking aperture array substrate 10, a reducing lens 12, a magnetic field correction lens 40, a stop aperture member 14, two objective lenses 16 and 17, and two electrostatic correction lenses 66 and 67.

[0020] The illumination lens 6 is disposed between the electron source 4 and the forming aperture array substrate 8. The illumination lens 6 can be a magnetic field lens or an electrostatic lens. The reducing lens 12 is disposed between the shielding aperture array substrate 10 and the object lens 16. The reducing lens 12 can be a magnetic field lens or an electrostatic lens. The object lenses 16 and 17 are magnetic field lenses.

[0021] The objective lens 17 is the one located on the downstream side of the beam travel direction among the plurality of objective lenses provided in the drawing device. The objective lens 16 is located on the upstream side of the beam travel direction, which is further upstream than the objective lens 17. Due to this positional relationship, the objective lens 16 is sometimes referred to as the upper objective lens, and the objective lens 17 is sometimes referred to as the lower objective lens. Furthermore, the objective lens 17 is sometimes referred to as the final objective lens.

[0022] As shown in Figures 1 and 2, the magnetic field correction lens 40 is positioned downstream of the object plane of the final objective lens 17 (the intermediate image IS1 described later), near the midpoint between the object plane of the objective lens 17 and the magnetic pole. Furthermore, the magnetic field correction lens 40 is positioned outside the lens magnetic fields of the objective lenses 16 and 17. The magnetic field (on-axis magnetic flux density) of a magnetic field type lens attenuates if it moves away from the lens magnetic pole. The point where the on-axis magnetic flux density is at its maximum is typically near the midpoint of a set of magnetic poles (two magnetic poles) of the magnetic field lens, that is, near the center of the gap between the magnetic field lenses on the optical axis. Empirically, relative to the maximum on-axis magnetic flux density, a region, for example, larger than 1 / 10, or a region where the magnetic flux density is at its minimum, is considered "inside the magnetic field," and the region outside of this is considered "outside the magnetic field."

[0023] As shown in Figure 2, the object lenses 16 and 17, which are composed of magnetic field 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. A portion of the pole pieces (magnetic 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 that form the gaps 16d and 17d of the magnetic field lenses in the optical axis direction (the lower ends of the pole pieces 16c1 and 17c1 on the upstream side of the beam travel 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 or distortions, sometimes the object lens of a segment is composed of two or more magnetic field lenses that are close to each other. However, in such cases, even if the magnetic flux density between the close magnetic field lenses that constitute the object lens of a segment becomes less than 1 / 10 or becomes extremely small, it will not be regarded as the boundary between the inside and outside of the lens magnetic field of the object lens, but will be regarded as "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 the central axis, through which the correction current flows. The coil can also 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 a vacuum, so it does not require a complex structure such as vacuum sealing, wiring leading out of the vacuum, or insulation support in the vacuum.

[0026] The electrostatic correction lenses 66 and 67 are disposed within the magnetic field of the object lens 17, which is composed of magnetic field lenses (that is, in 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 image. For example, the electrostatic correction lenses 66 and 67 are composed of cylindrical electrodes to which a correction voltage is applied. Cylindrical grounding electrodes may also be arranged before and after the electrodes to which the voltage is applied.

[0028] Alternatively, the cylindrical or annular electrodes are divided (for example, like an octet deflector), and the voltage generated by the focusing electric field (rotationally symmetric electric field), deflecting electric field, multipole electric field, etc., is applied to these electrode groups to serve as lenses, deflectors, multipoles, etc. Such a configuration also generates an electric field with a lens effect, so such an electrode group is also included in an electrostatic correction lens.

[0029] An XY platform 22 is disposed within the drawing chamber 20. A substrate 24 of the object to be drawn is placed on the XY platform 22. The substrate 24 of the object to be drawn is, for example, a mask blank or a semiconductor substrate (silicon wafer).

[0030] The electron beam 30 emitted from the electron source 4 illuminates the shaped aperture array substrate 8 nearly perpendicularly through the illumination lens 6. Figure 3 is a conceptual diagram illustrating the structure of the shaped aperture array substrate 8. The shaped aperture array substrate 8 has m columns (y-direction) × n columns (x-direction) (m, n ≥ 2) of openings 80 arranged in a matrix with a predetermined spacing. For example, 512 × 512 columns of openings 80 are formed. Each opening 80 is formed from a rectangle of the same size and shape. Each opening 80 may also be a circle of the same diameter.

[0031] An electron beam 30 illuminates the area containing all the openings 80 of the shaped aperture array substrate 8. A portion of the electron beam 30 passes through the plurality of openings 80, thereby forming a multi-beam 30M as shown in FIG1.

[0032] In the aperture array substrate 10, through holes are formed in accordance with the arrangement positions of each opening 80 of the shaped aperture array substrate 8, and a shield composed of two pairs of electrodes is disposed in each through hole. The multiple beams 30M passing through each through hole are independently deflected by the voltage applied to the shield. By this deflection, each beam is controlled to be shielded. In this way, the aperture array substrate 10 shields and deflects each beam of the multiple beams 30M passing through the plurality of openings 80 of the shaped aperture array substrate 8.

[0033] The multiple beams 30M passing through the obscured aperture array substrate 10 are reduced in size and spacing by the reducing lens 12, advancing in such a way that an intersection point CO1 is formed slightly upstream of the objective lens 16. The upper objective lens 16 acts on the multiple beams 30M that form the intersection point CO1, causing them to be imaged as an intermediate image IS1 formed by reducing the size of the plurality of openings 80 of the formed aperture array substrate 8, and an intersection point CO2 is formed between the intermediate image IS1 and the substrate 24. Furthermore, the imaging plane of the intermediate image IS1 corresponds to the object plane of the final objective lens 17.

[0034] A stop aperture member 14 is disposed near the magnetic pole of the objective lens 17, such that the center and intersection point of the opening formed in the stop aperture member 14 are almost aligned. Here, an electron beam deflected by the shield of the aperture array substrate 10 will have its trajectory shifted and its position deviated from the opening of the stop aperture member 14, and will be shielded by the stop aperture member 14. On the other hand, an electron beam not deflected by the shield of the aperture array substrate 10 will pass through the opening of the stop aperture member 14.

[0035] In this way, the stop aperture member 14 shields each electron beam that is biased to the beam-off state by the shielding device of the shielding aperture array substrate 10. Then, the beam passing through the stop aperture member 14 from the time the beam is turned on until the beam is turned off becomes a single firing electron beam.

[0036] The lower objective lens 17 reduces the intermediate image IS1, so that the image (beam array image) IS2 of the plurality of openings 80 of the formed aperture array substrate 8 at the desired reduction rate is imaged on the surface of the substrate 24. In this way, the objective lenses 16 and 17 align the focal point of the electron beam on the substrate 24 (surface). Furthermore, the reduction rate is the reciprocal of the magnification, for example, referring to the ratio of the size (or spacing) of the electron beam formed by a portion of the electron beam 30 passing through each of the plurality of openings 80 of the formed aperture array substrate 8 to the size (or spacing) of the image imaged on the surface of the substrate 24.

[0037] By designing the objective lens as two segments, a very high reduction ratio (e.g., a magnification of 1 / 200) can be achieved, and an interval (working distance) is ensured between the final segment lens (objective lens 17) and the substrate 24 for the substrate 24 to move.

[0038] The electrostatic correction lenses 66 and 67 are capable of operating relative to the surface of the substrate 24 in a positive voltage range, a negative voltage range, or a voltage range containing both polarities.

[0039] Each electron beam (all of the multiple beams) passing through the stop aperture member 14 is deflected in the same direction by a deflector (not shown) and irradiates the substrate 24. The deflector (not shown) only needs to be positioned downstream of the blocking aperture array substrate 10, but positioning it downstream of the object lens 16 above has the advantage of less distortion or aberration. As the XY platform 22 moves continuously, the irradiation position of the beams is deflected in a manner that follows the movement of the XY platform 22. Furthermore, as the XY platform 22 moves, the drawing position changes constantly, and the height of the surface of the substrate 24 irradiated by the multiple beams changes. Therefore, by means of the magnetic field correction lens 40 and the electrostatic correction lenses 66, 67, the focus deviation of the multiple beams is dynamically corrected during drawing (dynamic focusing).

[0040] Ideally, the multiple beams irradiated at one time would be arranged side by side with a spacing between them equal to the distance between the arrangement of the plurality of openings 80 of the formed aperture array substrate 8 divided by the aforementioned desired reduction rate (i.e., multiplied by the magnification). This drawing device performs the drawing operation by continuously and sequentially irradiating the emitted beams in a raster scan manner. When drawing the desired pattern, depending on the pattern, the necessary beams are controlled to be turned on by the masking control.

[0041] The control unit C includes a control computer 32 and a control circuit 34. The control computer 32 performs multi-segment data transformation processing on the drawing data to generate device-specific firing data, which is then output to the control circuit 34. The firing data defines the irradiation amount and irradiation position coordinates for each firing. The control circuit 34 divides the irradiation amount of each firing by the current density to calculate the irradiation time. When a corresponding firing is performed, a bias voltage is applied to the corresponding shielding device of the shielding aperture array substrate 10, so that the beam is turned on only for the calculated irradiation time.

[0042] The control computer 32 maintains data on the relationship between the excitation quantities of the magnetic field correction lens 40, the electrostatic correction lenses 66, and 67 (described later), and calculates the excitation quantity of each correction lens using this relationship. The control circuit 34 applies the excitation quantity calculated from the relationship to the magnetic field correction lens 40, the electrostatic correction lens 66, and 67 to activate them. Furthermore, the excitation quantity is the excitation current in the magnetic field correction lens and the applied voltage in the electrostatic correction lens.

[0043] The magnetic field correction lens has the effect of rotating the beam image (rotation effect), which occurs regardless of whether the optical axis of the magnetic field correction lens is within or outside the magnetic field of the object lens. The image rotation is simply the sum of the rotation effect of the object lens's magnetic field and the rotation effect of the magnetic field correction lens's magnetic field; even if the two magnetic fields overlap, there is no multiplicative effect (the rotation effect is proportional to the product of the two magnetic fields). Furthermore, in this embodiment, when the reducing lens 12 is a magnetic field lens, the rotation effect of the reducing lens is also added to the image rotation.

[0044] When a magnetic field correction lens is placed within the lens's magnetic field, the sensitivity of image height correction increases, and the magnification correction effect also increases. This is because the focusing force of the lens's magnetic field is proportional to the square of the on-axis magnetic flux density. Therefore, if the magnetic field of the object lens and the magnetic field correction lens overlap in the optical axis direction, a multiplier effect occurs (a focusing effect proportional to the product of the two magnetic fields), resulting in a large change in focusing force relative to a small change in the correction lens's magnetic field. On the other hand, if the magnetic field 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, which is disposed outside the lens magnetic field as in this embodiment, has the characteristics of low correction sensitivity for imaging height and magnification, but high correction sensitivity for rotation.

[0046] The electrostatic lens, positioned within the magnetic field of the objective lens (magnetic field lens), alters the energy of the beam within the electrostatic lens, changing the focusing effect of the beam from the magnetic field lens, thereby changing the imaging height. Due to this change in focusing effect, the magnification also changes. Rotation typically does not occur with a standalone electrostatic lens, but when positioned within the lens's magnetic field, the energy change causes rotation to occur through the magnetic field lens. Here, the magnetic field generated by the objective lens is extremely strong for beam imaging; therefore, even a small change in the applied voltage to the electrostatic lens results in a small energy change, significantly altering the focusing and rotation effects of the entire lens magnetic field. Therefore, the electrostatic correction lenses 66 and 67, positioned within the lens magnetic field of the final objective lens 17, exhibit high sensitivity in correcting imaging height, magnification, and rotation.

[0047] Furthermore, to explore in detail the correction sensitivities of the electrostatic correction lenses 66 and 67 within the magnetic field of the objective lens, the correction sensitivity depends on the magnetic field strength (magnetic flux density) of the objective lens at the position of the electrostatic correction lens and the beam trajectory value (distance from the optical axis). In addition, the imaging height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity are not mutually dependent. Even within the final objective lens magnetic field, the positions of the two electrostatic correction lenses 66 and 67 are offset along the beam optical axis, resulting in different magnetic field strengths or trajectory values ​​at each position. Therefore, the ratios of the correction sensitivities of the electrostatic correction lenses 66 and 67 (ratios of imaging height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity) are different.

[0048] As such, the magnetic field correction lens 40, electrostatic correction lenses 66 and 67 have different correction characteristics (different ratios of imaging height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity). Therefore, by controlling the excitation amount of these three correction lenses (applied voltage for the electrostatic correction lens and excitation current for the magnetic field correction lens) in a suitable relationship, the following imaging state corrections can be performed: • To address changes in the surface height of the substrate, the imaging height is changed without rotation and without magnification. • With the surface height of the substrate set to a constant, the magnification is changed without rotation and without a constant imaging height. • With the surface height of the substrate set to a constant, the rotation is changed without changing the imaging height and without changing the magnification. Of the above three types of imaging state corrections, the first correction utilizes focus correction (dynamic focusing) performed during drawing to address the unevenness of the sample surface. The second correction can be used for fine adjustment of magnification, and the third correction can be used for fine adjustment of rotation.

[0049] The relationship between the excitation amount and the adjustment in the imaging state are different for each of the three conditions mentioned above. The relationship between the excitation amount and the adjustment amount (imaging height, magnification, rotation) can be adjusted with sufficient accuracy by defining it as a polynomial of degree one or higher. The coefficients of the polynomial are obtained through orbital simulation. Alternatively, the coefficients can be calculated based on the measured dependence of the excitation amount on imaging height, magnification, and rotation.

[0050] As described above, the magnetic field correction lens 40 can be disposed outside a vacuum, and its diameter can be increased compared to the electrostatic correction lenses 66 and 67. Therefore, even if the beam passes through a track that deviates from the central axis of the magnetic field correction lens 40, the effect of the beam track being bent will be reduced. Therefore, the beam position of the stop aperture member 14 is stable, and the deterioration of the shielding characteristics can be suppressed.

[0051] The magnetic field correction lens 40 is positioned near the midpoint between the object plane and the magnetic pole of the final objective lens. Therefore, compared to the conventional electrostatic correction lens positioned in the lens magnetic field of the upper objective lens, the distance to the final objective lens is shorter, which can suppress the influence of axis deviation on the trajectory deviation of the final objective lens.

[0052] The electrostatic correction lenses 66 and 67 are positioned at almost the same height as the magnetic poles of the final objective lens, and the distance to the optical axis of the magnetic poles is extremely short. Therefore, even if the central axis of the electrostatic correction lenses 66 and 67 deviates from the central axis of the final objective lens and the beam track is bent, the beam will still be incident near the center of the final objective lens.

[0053] This suppresses the degradation of the characteristics of the multiple beams irradiating the substrate 24 (distortion of the beam array shape or aberration of the beam), thereby stabilizing the beam irradiation position and size. Since the beam position of the stop aperture member 14 hardly changes, the shielding characteristics do not deteriorate, and the beam irradiation amount is stabilized.

[0054] In the first embodiment described above, the magnetic field correction lens 40 disposed outside the vacuum has ample space, so a moving mechanism that makes the magnetic field correction lens 40 move slightly in the XY direction (horizontal direction) can also be provided. By using the moving mechanism to make slight adjustments to the magnetic field correction lens 40, the deviation 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 arranged in the magnetic field of the object lens, so the correction sensitivity is increased, the voltage required for correction can be suppressed to a lower level, and the burden on the driving circuit of the electrostatic correction lens can be reduced (technical and cost aspects).

[0056] In contrast, for example, if a corrective electrostatic lens is moved upstream and positioned outside the objective lens magnetic field, the excitation amount of the electrostatic corrective lens can be linked to correct the imaging state. However, the applied voltage (absolute value of the applied voltage) for the electrostatic corrective lens outside the objective lens magnetic field becomes higher. For example, to perform a 5μm imaging height correction, a voltage of up to 120V is applied according to the above embodiment, but when the electrostatic corrective lens is positioned outside the objective lens magnetic field, a voltage one order of magnitude higher, such as 1100V, must be applied. Thus, if the electrostatic corrective lens is positioned outside the objective lens magnetic field, the applied voltage becomes higher, increasing the cost of the drive circuit.

[0057] [Second Embodiment] In the first embodiment described above, the configuration in which the intersection point CO2 is formed upstream of the electrostatic correction lenses 66 and 67 was explained. However, as shown in FIG4, the intersection point CO2 can also be formed at the height between the electrostatic correction lenses 66 and 67. In this case, the stop aperture member 14 is aligned with the height of the intersection point CO2 and is disposed between the electrostatic correction lenses 66 and 67.

[0058] Even with such a configuration, the degradation of the beam characteristics and shielding characteristics of the multi-beam system can still be suppressed, just like in the first embodiment described above.

[0059] [Third Embodiment] In the first embodiment described above, the configuration in which the stop aperture member 14 is positioned at the height of the intersection point CO2 was explained. However, as shown in FIG5, the stop aperture member 14 can also be positioned at the height of the intersection point CO1 near the magnetic pole of the upstream objective lens 16. The intersection point CO1 is formed on the upstream side of the beam travel direction, which is further upstream than the object surface of the final objective lens 17.

[0060] Even with this configuration, the degradation of multi-beam characteristics can still be suppressed, just like in the first embodiment described above. Furthermore, by positioning the stop aperture member 14 upstream of the correction lens, the degradation of the blocking characteristics caused by axis deviation will not occur.

[0061] [Fourth Embodiment] In the first embodiment described above, a configuration in which the magnetic field correction lens 40 is disposed outside the lens magnetic field of the object lenses 16 and 17 was described. However, as shown in FIG6, the magnetic field correction lens 40 can also be moved downstream and disposed within the lens magnetic field of the object lens 17.

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

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

[0064] The magnetic field correction lens 40 and the electrostatic correction lenses 66 and 67 have different magnetic field strengths and beam trajectory values ​​at their respective positions, and also differ in type (magnetic field type and electrostatic type). Therefore, the ratios of correction sensitivities (the ratios of imaging height correction sensitivity, magnification correction sensitivity, and rotation correction sensitivity) of the magnetic field correction lens 40 and the electrostatic correction lenses 66 and 67 are different. Therefore, by controlling the excitation amount of the correction lenses with their different correction characteristics in a linked manner based on the relationship, the imaging height, magnification, and rotation of the beam array image IS2 can be appropriately adjusted.

[0065] [Fifth Embodiment] In the first embodiment described above, the configuration in which the magnetic field correction lens 40 is disposed downstream of the object plane (intermediate image plane) of the comparison lens 17 is described. However, the position of the magnetic field correction lens 40 is not limited to this, as long as it is disposed downstream of the obscuring aperture array substrate 10.

[0066] For example, as shown in FIG7, the magnetic field correction lens 40 can also be positioned upstream of the magnetic pole of the object lens 16 in the upper section, and outside the lens magnetic field of the object lens 16. Compared with the first embodiment described above, although the distance to the final object lens is longer, the magnetic field correction lens 40 can be positioned outside a vacuum and its diameter can be increased. Therefore, even if the beam passes through a track that deviates from the central axis of the magnetic field correction lens 40, the effect of the beam track being bent will be reduced, and the degradation of the beam characteristics and shielding characteristics of multiple beams can be suppressed.

[0067] In the current description, the electrostatic correction lenses 66 and 67 are designed to operate relative to the surface of the substrate 24 within a positive voltage range, a negative voltage range, or a voltage range containing both polarities. However, when operating within a 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 will remain near the junction of the two electrostatic correction lenses, and the beam position may become unstable due to the influence of the retained secondary electrons. However, such instability may not necessarily cause a problem. Depending on the magnetic field distribution of the objective lens, the inner diameter or positional relationship of the focal correction lens, or the required accuracy, it may not cause a problem. Furthermore, if they operate relative to the surface of the substrate 24 within a negative voltage range, the amount of secondary electrons generated on the substrate 24 entering the electrostatic correction lenses 66 and 67 can be significantly reduced, thus preventing the aforementioned beam position instability and avoiding problems.

[0068] In the illustrated device shown so far, the configuration using three correction lenses is explained, but the correction lenses used for the correction of the imaging state are not limited to three, and may also be four or more.

[0069] In addition, although the illustrated device so far has been shown to use a configuration with two objective lenses, it is also possible to use three or more objective lenses.

[0070] Although the present invention has been described in detail using specific embodiments, those skilled in the art will understand that various modifications can be made within the scope of achieving the effects of the invention. This application is based on Japanese Patent Application No. 2024-071661, filed on April 25, 2024, the entirety of which is incorporated herein by reference. [Simplified Explanation of the Diagram]

[0015] [Fig. 1] A schematic diagram of the multi-charged particle beam drawing apparatus according to the first embodiment of the present invention. [Fig. 2] A diagram illustrating the arrangement of the magnetic field correction lens and the stop aperture member. [Fig. 3] A schematic diagram of the formed aperture array substrate. [Fig. 4] A diagram illustrating the arrangement of the magnetic field correction lens and the stop aperture member according to the second embodiment. [Fig. 5] A diagram illustrating the arrangement of the magnetic field correction lens and the stop aperture member according to the third embodiment. [Fig. 6] A diagram illustrating the arrangement of the magnetic field correction lens and the stop aperture member according to the fourth embodiment. [Fig. 7] A diagram illustrating the arrangement of the magnetic field correction lens and the stop aperture member according to the fifth embodiment.

Claims

1. A multi-charged particle beam irradiation apparatus, comprising: a plurality of shielding devices for shielding and deflecting each beam of the multi-charged particle beam; a stop aperture member for shielding the beams that have been deflected by the plurality of shielding devices to a beam-closed state; two or more object lenses, formed of magnetic field lenses, for aligning the focal point of the multi-charged particle beams onto a substrate of the irradiated object; three or more correction lenses for correcting the imaging state of the multi-charged particle beams on the substrate; the three or more correction lenses comprising one magnetic field correction lens and two electrostatic correction lenses, the two electrostatic correction lenses being disposed within the lens magnetic field of the final object lens closest to the substrate among the two or more object lenses, and the magnetic field correction lens being disposed between the object surface and the magnetic pole of the final object lens.

2. A multi-charged particle beam irradiation apparatus, comprising: a plurality of shielding devices for shielding and deflecting each beam of the multi-charged particle beam; a stop aperture member for shielding the beams deflected by the plurality of shielding devices to a beam-closed state; two or more object lenses, formed of magnetic field lenses, for aligning the focal point of the multi-charged particle beams onto a substrate of the irradiated object; three or more correction lenses for correcting the imaging state of the multi-charged particle beams on the substrate; the three or more correction lenses comprising one magnetic field correction lens and two electrostatic correction lenses, the two electrostatic correction lenses being disposed within the lens magnetic field of the final object lens closest to the substrate among the two or more object lenses; the magnetic field correction lens being disposed upstream of the upper object lens in the beam travel direction, and outside the lens magnetic field of the upper object lens; wherein... The upper objective lens is the one among the aforementioned two or more objective lenses that is positioned upstream of the beam travel direction, even further upstream than the aforementioned final objective lens.

3. The multi-charged particle beam irradiation apparatus as described in claim 1 or 2, wherein, The aforementioned stop aperture member is configured to correspond to the position of the intersection point between the object surface of the aforementioned final segment objective lens and the aforementioned substrate.

4. The multi-charged particle beam irradiation apparatus as described in claim 1 or 2, wherein, The aforementioned stop aperture member is configured corresponding to the position of the intersection point formed on the upstream side of the object surface of the aforementioned final segment objective lens, which is further upstream in the beam travel direction.

5. The multi-charged particle beam irradiation apparatus as described in claim 1, wherein, The aforementioned magnetic field correction lens is positioned outside the lens magnetic field of the aforementioned two or more object lenses.

6. The multi-charged particle beam irradiation apparatus as described in claim 1, wherein, The aforementioned magnetic field correction lens is positioned within the lens magnetic field of the aforementioned final object lens.

7. The multi-charged particle beam irradiation apparatus as described in claim 1 or 2, wherein, The relationship between the excitation amounts of the aforementioned three or more correction lenses is established to correct the aforementioned imaging state of the aforementioned multi-charged particle beam.

8. The multi-charged particle beam irradiation apparatus as described in claim 7, wherein, The aforementioned correction to the imaging state refers to the correction of the imaging height without changing the magnification or rotation.

9. The multi-charged particle beam irradiation apparatus as described in claim 7, wherein, The aforementioned correction to the imaging state refers to the correction of changing the magnification without rotation and with the imaging height remaining constant.

10. The multi-charged particle beam irradiation apparatus as described in claim 7, wherein, The aforementioned correction to the imaging state is a correction that changes the rotation while keeping the imaging height and magnification constant.

11. The multi-charged particle beam irradiation apparatus as described in claim 3, wherein, The aforementioned stop aperture member is configured in a position corresponding to the intersection point formed between the aforementioned two electrostatic correction lenses.

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