Multi charged particle beam writing apparatus

A multi charged particle beam writing apparatus includes an aperture member to form multiple beams, a blanking plate in which there are arranged a plurality of blankers to respectively perform blanking deflection for a corresponding beam in the multiple beams having passed through a plurality of openings of the aperture member, a blanking aperture member to block each beam having been deflected to be in OFF state by at least one of the plurality of blankers, a first grating lens, using the aperture member as gratings, to correct spherical aberration of the charged particle beam, and a correction lens configured to correct high order spherical aberration produced by the first grating lens.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2014-041814 filed on Mar. 4, 2014 in Japan, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multi charged particle beam writing apparatus. More specifically, for example, the present invention relates to a method of correcting aberrations produced when irradiating multi-beams onto a target object on the stage.

2. Description of Related Art

The lithography technique that advances miniaturization of semiconductor devices is extremely important as a unique process whereby patterns are formed in semiconductor manufacturing. In recent years, with high integration of LSI, the line width (critical dimension) required for semiconductor device circuits is decreasing year by year. The electron beam (EB) writing technique, which intrinsically has excellent resolution, is used for writing or “drawing” a pattern on a wafer and the like with electron beams.

As an example employing the electron beam writing technique, a writing apparatus using multiple beams (multi beams) can be cited. Compared with the case of writing a pattern by using a single electron beam, since it is possible to emit multiple beams at a time in multi-beam writing, the throughput can be greatly increased. For example, in a writing apparatus employing a multi-beam system, multiple beams are formed by letting an electron beam emitted from an electron source assembly pass through a mask with a plurality of holes, blanking control is performed for each of the beams, and each unblocked beam irradiates a desired position on a target object (refer to, e.g., Japanese Published Unexamined Patent Application (JP-A) No. 2006-261342).

In multi beam writing, since the beam size of the entire multi-beams is large, aberrations on the optical axis of a crossover image forming system become large. Therefore, it is necessary to form an aperture (contrast aperture) for blanking arranged near a crossover to have a large aperture diameter. However, when the diameter of the aperture is large, a new problem occurs in that it becomes necessary to increase a blanking voltage for blanking control. Therefore, it is desirable to make geometric aberrations themselves of multi-beams small.

BRIEF SUMMARY OF THE INVENTION

According to one aspect of the present invention, a multi charged particle beam writing apparatus includes a stage configured to mount a target object thereon and to be continuously movable, an emission unit configured to emit a charged particle beam, an aperture member, in which a plurality of openings are formed, configured to form multiple beams by letting a region including a whole of the plurality of openings be irradiated with the charged particle beam and letting portions of the charged particle beam respectively pass through a corresponding opening of the plurality of openings, a blanking plate in which there are arranged a plurality of blankers configured to respectively perform blanking deflection for a corresponding beam in the multiple beams having passed through the plurality of openings of the aperture member, a blanking aperture member configured to block each beam having been deflected to be in OFF state by at least one of the plurality of blankers, a first grating lens, using the aperture member as gratings, configured to correct spherical aberration of the charged particle beam, and a correction lens configured to correct high order spherical aberration produced by the first grating lens.

According to another aspect of the present invention, a multi charged particle beam writing apparatus includes a stage configured to mount a target object thereon and to be continuously movable, an emission unit configured to emit a charged particle beam, an aperture member, in which a plurality of openings are formed, configured to form multiple beams by letting a region including a whole of the plurality of openings be irradiated with the charged particle beam and letting portions of the charged particle beam respectively pass through a corresponding opening of the plurality of openings, a blanking plate in which there are arranged a plurality of blankers configured to respectively perform blanking deflection for a corresponding beam in the multiple beams having passed through the plurality of openings of the aperture member, an illumination lens configured to illuminate the charged particle beam onto the region of the aperture member, a blanking aperture member configured to block each beam having been deflected to be in OFF state by at least one of the plurality of blankers, and a foil lens, arranged between the illumination lens and the aperture member, configured to correct spherical aberration of the charged particle beam.

DETAILED DESCRIPTION OF THE INVENTION

In the following embodiments, there will be described a configuration in which an electron beam is used as an example of a charged particle beam. The charged particle beam is not limited to the electron beam, and other charged particle beam such as an ion beam may also be used.

Moreover, in the following embodiments, there will be described a writing apparatus capable of correcting geometric aberrations of multi-beams.

First Embodiment

FIGS. 1A to 1Care conceptual diagrams showing a configuration of a writing or “drawing” apparatus according to the first embodiment. InFIG. 1A, a writing apparatus100includes a writing unit150and a control unit160. The writing apparatus100is an example of a multi charged particle beam writing apparatus. The writing unit150includes an electron optical column102and a writing chamber103. In the electron optical column102, there are arranged an electron source assembly201, an illumination lens202, a blanking aperture array212, a reducing lens205, a limiting aperture member206(blanking aperture), an objective lens207, an electrode group214, and an electrostatic lens218. In the blanking aperture array212, an aperture member203at the side of the electron source assembly201(upstream side) and a blanking plate204are arranged.

As shown inFIG. 1B, the electrode group214(first and second electrodes) is arranged between the illumination lens202and the blanking aperture array212and composed of at least two stages of electrodes each having a central opening. The electrode group214is composed of an electrode (first electrode) which is earthed (connected to ground) at the side of the illumination lens202and an electrode (second electrode) which is arranged at a position closest to the blanking aperture array212and to which voltage is applied. An electrostatic lens is composed of the electrode group214. A grating lens216(first grating lens) is composed of the electrode group214and the aperture member203. As shown inFIG. 10, an electrostatic lens218(correction lens) is composed of at least three stages of electrodes each having a central opening and arranged between the illumination lens202and the electrode group214. The electrostatic lens218is an einzel lens including at least two stages of electrodes (third and fourth electrodes) which are earthed (connected to ground) and at least one stage of an electrode (fifth electrode) which is arranged between the third and fourth electrodes and to which voltage is applied.

In the writing chamber103, there is arranged an XY stage105. On the XY stage105, there is placed a target object or “sample”101such as a mask serving as a writing target substrate when writing is performed. The target object101is, for example, an exposure mask used for manufacturing semiconductor devices, or is a semiconductor substrate (silicon wafer) on which semiconductor elements are formed. The target object101may be, for example, a mask blank on which resist has been applied but a pattern has not yet been written.

Both the reducing lens205and the objective lens207are composed of electromagnetic lenses and arranged so that their magnetic fields on an axis may be in opposite directions and the amount of excitation of each lens may be equal to each other.

The control unit160includes a control computer110, a control circuit112, lens control circuits120and122, and storage devices140and142such as magnetic disk drives. The control computer110, the control circuit112, the lens control circuits120and122, and the storage devices140and142are connected to each other through a bus (not shown).

FIGS. 1A to 1Cshow a configuration necessary for explaining the first embodiment. Other configuration elements generally necessary for the writing apparatus100may also be included.

FIGS. 2A and 2Bare conceptual diagrams each showing an example of the configuration of an aperture member according to the first embodiment. InFIG. 2A, holes (openings)22of m rows long (y direction) and n columns wide (x direction) (m≧2, n≧2) are formed, like a matrix, in the aperture member203at a predetermined arrangement pitch. InFIG. 2A, for example, holes22of 512 (rows)×8 (columns) are formed. Each of the holes22is a quadrangle of the same dimensional shape. Alternatively, each of the holes22can be a circle of the same circumference. Here, there is shown an example in which each of the rows that are arrayed in the y direction has eight holes22from A to H in the x direction. Multi-beams20are formed by letting portions of an electron beam200respectively pass through a corresponding hole of a plurality of holes22. The case in which the holes22of two or more rows and columns are arranged in both the x and the y directions is shown here, but the arrangement is not limited thereto. For example, it is also acceptable that a plurality of holes22are arranged in only one row (x direction) or in only one column (y direction). That is, in the case of only one row, a plurality of holes22are arranged as a plurality of columns, and in the case of only one column, a plurality of holes22are arranged as a plurality of rows. Moreover, the method of arranging the holes22is not limited to the case ofFIG. 2Awhere holes are arranged like a grid in the length and width directions. For example, as shown inFIG. 2B, as to the first and second rows arrayed in the length direction (y direction), each hole in the first row and each hole in the second row may be mutually displaced in the width direction (x direction) by a dimension “a”. Similarly, as to the second and third rows arrayed in the length direction (y direction), each hole in the second row and each hole in the third row may be mutually displaced in the width direction (x direction) by a dimension “b”, for example.

FIG. 3is a conceptual diagram showing the configuration of a blanking plate according to the first embodiment. In the blanking plate204, a passage hole is formed to be corresponding to the arrangement position of each hole22of the aperture member203, and a pair of electrodes24and26(blanker: first deflector) is arranged for each passage hole. An electron beam20passing through a corresponding passage hole is deflected by the voltage respectively applied to the two electrodes24and26being a pair. Blanking control is performed by such deflection. Thus, a plurality of blankers respectively perform blanking deflection of a corresponding beam in the multi-beams having passed through a plurality of holes22(openings) of the aperture member203.

The control computer110reads writing data from the storage device140, and performs data conversion of a plurality of steps so as to generate shot data. The shot data defines, for example, whether or not each irradiation region obtained by dividing the writing surface of the target object101into a plurality of grid-like irradiation regions by, for example, the beam size is irradiated, an irradiation time, and the like. Based on the shot data, the control computer110outputs a control signal to the control circuit112, and the control circuit112controls the writing unit150in accordance with the control signal. Under the control of the control circuit112, the writing unit150writes a pattern on the target object101by using the multi-beams20. At this time, the lens control circuit120controls the electrode group214, and applies a voltage to the electrode group214. The lens control circuit122controls the electrostatic lens218, and applies a voltage to the electrostatic lens218. The writing unit150operates as described below.

The electron beam200emitted from the electron source assembly201(emission unit) almost perpendicularly (e.g., vertically) illuminates the whole of the aperture member203by the illumination lens202. A plurality of holes (openings) each being a quadrangle are formed in the aperture member203. The region including all the plurality of holes is irradiated with the electron beam200. For example, a plurality of quadrangular electron beams (multi-beams)20ato20eare formed by letting portions of the electron beam200irradiating the positions of a plurality of holes pass through a corresponding hole of the plurality of holes of the aperture member203respectively. The multi-beams20ato20erespectively pass through corresponding blankers (first deflectors) of the blanking plate204. Each blanker deflects (performs blanking deflection) the passing electron beam20. The multi-beams20a,20b, . . . ,20e, having passed through the blanking plate204are reduced by the reducing lens205, and travel toward the hole at the center of the limiting aperture member206. At this time, the electron beam20deflected by the blanker of the blanking plate204deviates from the hole at the center of the limiting aperture member206(blanking aperture member) and is blocked by the limiting aperture member206. On the other hand, the electron beam20not deflected by the blanker of the blanking plate204passes through the hole at the center of the limiting aperture member206. Blanking control is performed by ON/OFF of the blanker so as to control ON/OFF of the beam. Thus, the limiting aperture member206blocks each beam which was deflected to be in the OFF state by each of a plurality of blankers. One beam shot is formed by a beam which has been formed during from a beam ON state to a beam OFF state and has passed through the limiting aperture member206. Pattern images of the multi-beams20having passed through the limiting aperture member206are focused by the objective lens207so as to irradiate respective beam irradiation positions on the target object101.

The writing apparatus100performs a writing operation by a raster scan method by which shot beams are successively emitted in order while the XY stage105is moving, and when a desired pattern is written, a necessary beam is controlled to be beam-ON by blanking control according to the pattern.

FIGS. 4A to 4Care conceptual diagrams explaining a writing operation according to the first embodiment. As shown inFIG. 4A, a writing region30of the target object101is virtually divided into a plurality of stripe regions32each in a strip shape and each having a predetermined width in the y direction, for example. Each of the stripe regions32serves as a unit of writing region. First, the XY stage105is moved to make an adjustment such that an irradiation region34which can be irradiated by one-time irradiation of the multi-beams20is located at the left end of the first stripe region32or at a position more left than the left end, and then writing is started. When writing the first stripe region32, the writing advances relatively in the x direction by moving the XY stage105in the −x direction, for example. The XY stage105is continuously moved at a predetermined speed, for example. After writing the first stripe region32, the stage position is moved in the −y direction to make an adjustment such that the irradiation region34is located at the right end of the second stripe region32or at a position more right than the right end, to be relatively located in the y direction. Then, similarly, as shown inFIG. 4B, writing advances in the −x direction by moving the XY stage105in the x direction, for example. That is, writing is performed while alternately changing the direction, such as performing writing in the x direction in the third stripe region32, and in the −x direction in the fourth stripe region32, and thus, the writing time can be reduced. However, the writing operation is not limited to the case of performing writing while alternately changing the direction, and it is also preferable to perform writing in the same direction when writing each stripe region32. By one shot, as shown inFIG. 4C, a plurality of shot patterns36whose number is equal to the number of the holes22are formed at a time by multi-beams which have been formed by passing through respective corresponding holes22of the aperture member203. For example, a beam which passed through a hole A of the aperture plate member203irradiates the position “A” shown inFIG. 4Cto form the shot pattern36at this position. Similarly, a beam which passed through a hole B of the aperture member203irradiates the position “B” shown inFIG. 4Cto form the shot pattern36at this position, for example. A similar operation applies to C to H. Thus, the writing apparatus100writes a pattern in each stripe32by the raster scan method by which shot beams are successively emitted in order while the XY stage105is moving in the x direction.

FIG. 5is a conceptual diagram describing the relation between the structure of a writing apparatus and aberrations according to Comparative Example 1 with respect to the first embodiment. Comparative Example 1 shown inFIG. 5is the same as the writing unit150ofFIG. 1except that the electrode group214and the electrostatic lens218do not exist. In multi beam writing, as described above, since the beam size of the entire multi-beams is large, aberrations (particularly spherical aberration) on the optical axis of a crossover image forming system become large. Therefore, it is necessary to form the limiting aperture206(contrast aperture) for blanking, arranged near a crossover, to have a large aperture diameter (refer to portion A inFIG. 5). However, when the diameter of the aperture is large, a new problem occurs in that it becomes necessary to increase a blanking voltage for blanking control.

FIG. 6is a conceptual diagram describing the relation between the structure of a writing apparatus and aberrations according to Comparative Example 2 with respect to the first embodiment. Comparative Example 2 shown inFIG. 6is the same as the writing unit150ofFIGS. 1A to 1Cexcept that the electrostatic lens218does not exist. In other words, in Comparative Example 2 ofFIG. 6, the electrode group214is arranged between the illumination lens202and the blanking aperture array212, and the grating lens216is composed of the electrode group214and the aperture member203. The grating lens is effective in correcting spherical aberration. By using the grating lens, spherical aberrations up to the third order can be corrected. However, when only the grating lens216of Comparative Example 2 ofFIG. 6is used, spherical aberration of the fifth order remains. That is, while spherical aberrations up to the third order can be reduced by using the grating lens216, spherical aberration of the fifth order (high order) increases.

Originally, in the state of Comparative Example 1 ofFIG. 5, spherical aberration of third order is large and spherical aberration of the fifth order is small. Then, in Comparative Example 2 ofFIG. 6, since the grating lens with negative spherical aberration is used, when both the states are united, spherical aberration of the third order reduces but spherical aberration of the fifth order increases. For example, with respect to coordinates x and y of the electron trajectory on the surface of the target object and derivatives x′ and y′ relating to coordinate z of the central axis of the electron trajectory, when w is expressed as w=x+iy (where i is an imaginary unit) and w′ is expressed as w′=x′+iy′ (where ′ denotes a derivative relating to the coordinate z of the central axis of the electron trajectory), aberration proportional to wb′w′w′ being a product of two w′s and one wb′ (where wb′ is a complex conjugate of w′) is the third order spherical aberration in the system of a rotational symmetry with respect to the z axis. Moreover, aberration proportional to wb′wb′w′w′w′ being a product of three w′s and two wb′s is the fifth order spherical aberration (where b is a complex conjugate). In the conventional system, the fifth order aberration has not been a problem. However, when the third order aberration is corrected, it becomes necessary to consider the fifth order aberration. According to the first embodiment, spherical aberration of the fifth order is also corrected.

FIG. 7is a conceptual diagram describing the relation between the structure of the writing apparatus and aberrations according to the first embodiment. As shown inFIG. 7, in the writing apparatus100of the first embodiment, the electrostatic lens218(correction lens) is arranged between the illumination lens202and the electrode group214. The electrostatic lens218corrects high order (e.g., fifth order) spherical aberration produced by the grating lens216.

FIGS. 8A to 8Care examples each showing the relation between the amount of trajectory displacement of multi-beams and the voltage applied to the lens according to the first embodiment. InFIGS. 8A to 8C, the ordinate axis shows the amount of trajectory displacement of multi-beams and the abscissa axis shows the voltage applied to the lens.FIG. 8Ashows the state in which spherical aberrations up to the third order have been reduced using the grating lens216. However, as shown inFIG. 8A, while the spherical aberration up to the third order have been reduced, spherical aberration of the fifth order increases. Then, according to the first embodiment, as shown inFIG. 8B, voltage is set such that the third order spherical aberration and the fifth order spherical aberration are daringly produced by the electrostatic lens218. In that case, as shown inFIG. 8C, voltage is set such that the third order spherical aberration and the fifth order spherical aberration are daringly produced by the electrostatic lens218in order that the remaining third order spherical aberration after using the grating lens216and the fifth order spherical aberration produced using the grating lens216may cancel each other out as much as possible. In other words, lens values (voltages) are respectively applied to the electrode group214and the electrostatic lens218such that the third order spherical aberration and the fifth order spherical aberration are cancelled out each other by using the grating lens216and the electrostatic lens218. Consequently, by the control described above, the amount of trajectory displacement of multi-beams can be reduced as shown inFIG. 8C.

With respect to voltages to be applied to the grating lens216and the electrostatic lens218(correction lens), a relation of voltage group (or voltage ratio) under which spherical aberration of the third order and spherical aberration of the fifth order become as small as possible using the grating lens216and the electrostatic lens218(correction lens) can be acquired in advance through experiment etc. Correlation data on an acquired voltage group (or voltage ratio) is stored as a correlation table in the storage device142. When the writing apparatus100is started and adjusted, the control computer110reads the correlation table from the storage device142, reads a voltage group (or voltage ratio) under which the amount of trajectory displacement becomes smaller from the correlation table, and outputs control signals each indicating a corresponding voltage of the voltage group to the lens control circuits120and122. The lens control circuit120applies a voltage in the relation of the voltage group (or voltage ratio) to the electrode group214, and the lens control circuit122applies the other voltage in the relation of the voltage group (or voltage ratio) to the electrostatic lens218.

As described above, according to the first embodiment, it is possible to correct geometric aberrations of multi-beams. Therefore, the diameter of the aperture for blanking can be small and a blanking voltage can also be small. Moreover, according to the first embodiment, it is possible to correct, particularly, high order geometric aberrations of multi-beams.

Second Embodiment

In the first embodiment, there has been described an example where a correction lens for correcting high order aberrations is arranged between the illumination lens202and the electrode group214, but it is not limited thereto. In the second embodiment, a case where a correction lens is arranged at a position different from that of the first embodiment will be described.

FIG. 9is a schematic diagram showing the configuration of a writing apparatus according to the second embodiment.FIG. 9is the same asFIG. 1Aexcept that an electrostatic lens220(correction lens) instead of the electrostatic lens218is arranged between the blanking aperture array212and reducing lens205, and that a lens control circuit124which controls the electrostatic lens220is arranged instead of the lens control circuit122. It is preferable that the electrostatic lens220is arranged just below the blanking aperture array212. The electrostatic lens220(correction lens) configures a grating lens222, being different from the grating lens216, by using the blanking plate204as gratings. Therefore, the electrostatic lens220(correction lens) is arranged opposite the grating lens216with respect to the aperture member203or the blanking plate204. The contents of the present embodiment are the same as those of the first embodiment except what is described below.

FIG. 10is a conceptual diagram describing the relation between the structure of the writing apparatus and aberrations according to the second embodiment. As shown inFIG. 10, in the writing apparatus100of the second embodiment, the electrostatic lens220(correction lens) is arranged opposite the grating lens216with respect to the aperture member203or the blanking plate204. The electrostatic lens220configures the grating lens222, and corrects a high order spherical aberration (e.g., fifth order) produced by the grating lens216. Multi-beams whose aberrations up to the third order have been corrected using the grating lens216proceed ahead while remaining in the state of a largely produced fifth order spherical aberration, which continues until the multi-beams pass through the aperture member203. By the grating lens222(second grating lens) composed of the blanking plate204and the electrostatic lens220, the third order spherical aberration and the fifth order spherical aberration are suppressed. Consequently, the spherical aberrations produced in multi-beams are corrected so that trajectory displacement of the multi-beams may become smaller.

With respect to voltages to be applied to the grating lens216(electrode group214) and the grating lens222(electrostatic lens220: correction lens), a relation of voltage group (or voltage ratio) under which spherical aberration of the third order and spherical aberration of the fifth order become as small as possible using the grating lens216and the grating lens222(electrostatic lens220: correction lens) can be acquired in advance through experiment etc. Correlation data on an acquired voltage group (or voltage ratio) is stored as a correlation table in the storage device142. When the writing apparatus100is started and adjusted, the control computer110reads the correlation table from the storage device142, reads a voltage group (or voltage ratio) under which the amount of trajectory displacement becomes smaller from the correlation table, and outputs control signals each indicating a corresponding voltage of the voltage group to the lens control circuits120and124. The lens control circuit120applies a voltage in the relation of the voltage group (or voltage ratio) to the electrode group214, and the lens control circuit124applies the other voltage in the relation of the voltage group (or voltage ratio) to the electrostatic lens220.

As described above, according to the second embodiment, it is possible to correct high order geometric aberrations of multi-beams similarly to the first embodiment. In the case of the second embodiment, high order geometric aberrations of multi-beams can be corrected by using the grating lens combined with the correction lens utilizing the blanking plate204.

Third Embodiment

In the first and second embodiments, there has been described an arrangement in which a correction lens for correcting high order aberrations is arranged at a position not associated with the magnetic field of an electromagnetic lens, such as the illumination lens202and the reducing lens205, but it is not limited thereto.

FIG. 11is a schematic diagram showing the configuration of a writing apparatus according to the third embodiment.FIG. 11is the same asFIG. 1except that a coil lens (electromagnetic lens)224(correction lens) instead of the electrostatic lens218is arranged in the magnetic field of the illumination lens202, and that a lens control circuit126for controlling the coil lens224is arranged instead of the lens control circuit122. It is preferable if the coil lens224is arranged at a position completely included in the magnetic field of the illumination lens202so that the influence of the magnetic field generated by the voltage applied to the coil lens224may efficiently act on the magnetic field of the illumination lens202. The contents of the present embodiment are the same as those of the first embodiment except what is described below.

With respect to voltages to be applied to the grating lens216(electrode group214) and the coil lens224(correction lens), a relation of voltage group (or voltage ratio) under which spherical aberration of the third order and spherical aberration of the fifth order become as small as possible using the grating lens216and the coil lens224can be acquired in advance through experiment etc. Correlation data on an acquired voltage group (or voltage ratio) is stored as a correlation table in the storage device142. When the writing apparatus100is started and adjusted, the control computer110reads the correlation table from the storage device142, reads a voltage group (or voltage ratio) under which the amount of trajectory displacement becomes smaller from the correlation table, and outputs control signals each indicating a corresponding voltage of the voltage group to the lens control circuits120and126. The lens control circuit120applies a voltage in the relation of the voltage group (or voltage ratio) to the electrode group214, and the lens control circuit126applies the other voltage in the relation of the voltage group (or voltage ratio) to the coil lens224.

As described above, according to the third embodiment, it is possible to correct high order geometric aberrations of multi-beams similarly to the first embodiment. In the case of the third embodiment, high order geometric aberrations of multi-beams can be corrected by arranging a correction lens in the magnetic field of an electromagnetic lens of the illumination system.

Fourth Embodiment

In embodiments described above, the configuration based on the premise of the grating lens216utilizing the aperture member203has been explained. In the fourth embodiment, there will be described a case in which the grating lens216utilizing the aperture member203is not used.

FIG. 12is a schematic diagram showing the configuration of a writing apparatus according to the fourth embodiment.FIG. 12is the same asFIG. 1except that a foil lens230instead of the electrode group214and the electrostatic lens218is arranged between the illumination lens202and the blanking aperture array212, and that a lens control circuit128for which controls the foil lens230(electrostatic lens226) is arranged instead of the lens control circuits120and122. The foil lens230includes the electrostatic lens226and a foil228. The contents of the present embodiment are the same as those of the first embodiment except what is described below.

In the embodiments described above, the electrode group214needs to be arranged close to the aperture member203in order that the grating lens216may be configured utilizing the aperture member203. On the other hand, according to the fourth embodiment, since the foil lens230including the foil228is used, it is possible to avoid limiting the arrangement position to be close to the aperture member203.

Here, the foil228is made of a member transmittable through an electron (charged particle). For example, it is preferable to use a diamond-like carbon (DLC) thin film, graphene, or the like. By using DLC, graphene, or the like composed of carbon having a small atomic number, scattering of electrons at the foil can be reduced. The foil228is configured to be larger than the size of the entire multi-beams, and arranged to be overlapped with the entire multi-beams or the whole of a plurality of apertures of the aperture member203.

In the case ofFIG. 12, as the foil lens230, the electrostatic lens226is arranged at the upstream side and the foil228is arranged at the downstream side, but the arrangement position may be reversed.

Spherical aberrations of an electron beam (multi-beams) are corrected by the foil lens230.

FIG. 13is a conceptual diagram describing the relation between the structure of the writing apparatus and aberrations according to the fourth embodiment. As shown inFIG. 13, in the writing apparatus100of the fourth embodiment, the foil lens230is arranged between the illumination lens202and the aperture member203. Spherical aberrations up to the third order of an electron beam (multi-beams) can be corrected by the foil lens230. In the example ofFIG. 13, although the spherical aberration of the fifth order still remains, since there is no restriction of arrangement position with respect to the aperture member203, the degree of freedom of design can be increased.

The lens control circuit128applies voltage to correct the spherical aberration of the third order to the electrostatic lens226.

By combining the correction lens of one of embodiments of the first to third with the configuration of the fourth embodiment, high order spherical aberrations are corrected.

The embodiments have been explained referring to concrete examples described above. However, the present invention is not limited to these specific examples. The raster scanning operation described above is just an example, and it is also acceptable to use other operation method instead of the raster scanning operation using multiple beams.

While the apparatus configuration, control method, and the like not directly necessary for explaining the present invention are not described, some or all of them may be suitably selected and used when needed. For example, although description of the configuration of the control unit for controlling the writing apparatus100is omitted, it should be understood that some or all of the configuration of the control unit is to be selected and used appropriately when necessary.

In addition, any other multi charged particle beam writing apparatus and method that include 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.