JP2001052998A - Method and device for imaging charged particle beam, and exposure device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a spherical aberration from increasing even when a convergence radius is substantially enlarged by splitting the charged particle beam into child beams using an aperture plate comprising a plurality of charged particle passage parts, with its part polarized. SOLUTION: An aperture plate 50 comprises a charged particle passage and a first charged particle passage opening 60 at the optical-axis center of an imaging lens 42, with annular second charged particle passage openings 61 and 62 provided around it. At the annular openings 61 and 62, an even electric field toward the center of a pupil surface is formed. The electron beam which has passed the openings 61 and 62 is polarized away from the optical axis of the imaging lens 42. With an applied electric power V1 set appropriately, the electron beam having passed the openings 61 and 62 is projected on the position x=0 on an image plane 44. While observing the imaging state of electron beam on the image plane 44, Vi is so set that a resolution is improved. Thus, the spherical aberration is prevented from increasing even when a convergence radius α is substantially extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a charged particle beam imaging method used in a charged particle beam exposure apparatus such as an electron beam exposure apparatus, an imaging apparatus, and a charged particle beam using such an imaging apparatus. The present invention relates to an exposure apparatus, for example, a charged particle beam imaging method and an imaging apparatus having a small aberration even when a beam convergence angle is substantially increased, and a charged particle beam exposure apparatus using such an imaging apparatus.

[0002]

2. Description of the Related Art In recent years, semiconductor technology has been developed more and more, and the degree of integration and functions of semiconductor integrated circuits (ICs) have been improved, and their role is expected as a core technology of technological progress in a wide range of industries such as computer and communication machine control. ing. ICs have achieved four times higher integration in two to three years. For example, a dynamic random access memory (DRAM: Dyna
mic random access memory), its storage capacity has increased to 1M, 4M, 16M, 256M, and 1G. Such high integration of ICs largely depends on the progress of fine processing technology in semiconductor manufacturing technology, particularly, exposure technology.

It is expected that the light exposure technology used in steppers and the like conventionally used is limited, and charged particle beam exposure technology such as electron beam exposure technology will take the next generation of fine processing in place of light exposure technology. This is a highly promising technology. In the following description, an electron beam exposure apparatus will be described as an example, but the present invention is not limited to this.
The present invention can be applied to a charged particle beam exposure apparatus, an imaging method thereof, and an imaging apparatus.

There are various types of electron beam exposure systems, such as a variable rectangular exposure system, a block exposure system, and a multi-beam exposure system. An electron beam exposure apparatus will be briefly described using a block exposure method as an example. The block exposure method is a method in which a pattern serving as a unit of a repeated figure is held on a transmission mask, an electron beam is transmitted through the mask to generate a unit pattern at a time, and the pattern is connected to expose the figure repeatedly.

FIG. 1 is a diagram showing the configuration of a beam irradiation system in a block exposure type electron beam exposure apparatus. In FIG. 1, an electron beam exposure apparatus includes an electron gun 11 for generating an electron beam, a first converging lens 12 for converting the electron beam from the electron gun 11 into a parallel beam, and forming the passing parallel beam into a predetermined shape. Aperture plate 13, a second converging lens 14 for narrowing the shaped beam, a shaping deflector 15, a first mask deflector 16, and a deflector for dynamically correcting astigmatism due to the mask 17, a second mask deflector 18, a mask focusing coil 19, a first shaping lens 20, a block mask 21 moved by a stage 21A, a second shaping lens 22, and a third shaping lens 22. Mask deflector 23, a blanking deflector 24 for controlling the beam on / off, and a fourth mask deflector 25
A third lens 26, a circular aperture 27, a reduction lens 28, a dynamic focus coil 29,
An imaging lens 30, an electromagnetic main deflector 31, an electrostatic sub deflector 32, and a backscattered electron detector for detecting backscattered electrons of the electron beam applied to the sample 1 and outputting a backscattered electron signal 33. The electron beam 10 is projected by the projection lens 30.
Is focused on the sample (wafer) 1 placed on the stage 2. The stage 2 moves the wafer 1 two-dimensionally in a plane perpendicular to the electron beam 10. The above parts are accommodated in a housing called an electron optical column (column), and the inside of the column is evacuated to perform exposure. The electron beam exposure apparatus further has an exposure control unit for controlling each part of the column so as to expose a desired pattern, but the description is omitted here.

The above-mentioned imaging lens 30 is generally made of an electromagnetic lens, but it can also be realized by an electrostatic lens or by a combination of an electromagnetic lens and an electrostatic lens. The electron beam is converged on the surface of the sample 1 by the imaging lens 30. The exposure position is changed by a main deflector 31 and a sub deflector 32 (hereinafter collectively referred to as deflectors). When the exposure position is largely changed, the sample is moved by the stage 2. Even in the block exposure method, the pattern exposed in one shot is 10 μm □ or less,
After being deflected to be adjacent by a deflector, exposure is performed in order.

The electron beam exposure method has extremely high resolution and depth of focus as compared with the light exposure method widely used in the manufacture of LSIs at present, and can draw a fine pattern at a level that cannot be realized by the light exposure method. However, on the other hand, there is a problem that the processing capability, that is, the throughput is remarkably lower than that of the light exposure method, so that mass productivity is inferior. The reason is as follows. In order to expose a resist material having a specific sensitivity at high speed, it is necessary to increase the amount of current of the electron beam on the sample surface. However, when the amount of current is increased, there is a problem that the resolving force between electrons deteriorates the resolution. This decrease is generally called the Coulomb effect. In order to reduce the Coulomb effect, the first method is to increase the accelerating voltage, the second method is to shorten the beam trajectory from beam shaping, and the third method is to increase the convergent half angle. Can be However, both the first and second methods include a factor that deteriorates the deflection efficiency of beam deflection. If the deflection efficiency is low, the waiting time for stabilizing the beam deflection becomes longer, which causes a problem of lowering the throughput. Therefore, these methods have limitations. Also, regarding the third method,
Since the electromagnetic lens using a coil has the characteristics of a spherical lens, there is a problem that if the convergent half angle α is made larger than a certain value, the aberration becomes large and the resolution is deteriorated. This will be further described with reference to the drawings.

FIG. 2 is a view for explaining the principle that the aberration increases as the convergence half angle α increases. There are four aberrations depending on α: spherical aberration, coma, astigmatism, and chromatic aberration. Techniques for correcting astigmatism are known, and coma can be made sufficiently small by column design, and chromatic aberration can be made sufficiently small by designing a light source. Therefore, what is usually considered as a problem is spherical aberration.

[0009] Spherical aberration is caused by the fact that the characteristics of an electromagnetic lens have the characteristics of a spherical lens, which is what is called an optical lens. As shown in FIG. 2, consider a case where point 0 is one point on the object surface 41, and the electron beam from point 0 passes through the pupil plane of the imaging lens 42 and forms an image on the image plane 44. A coordinate axis a having the optical axis as the origin is provided on the pupil plane, and a coordinate axis x having the optical axis as the origin is provided on the image plane 44. At this time, considering the spherical aberration of the imaging (spherical) lens 42, the electron beam that has passed from the point 0 and passed through the position of a = r on the pupil plane becomes x
= Cr ³ is projected. Here, c is a constant. Therefore, when the size of the aperture 43 on the pupil plane and to ± R, aberration of the image on the image plane 44 is approximately cR ^3. on the other hand,
Since the convergence half angle α is proportional to R, the spherical aberration becomes the convergence half angle α
Is proportional to the cube of.

As described above, since the electromagnetic lens formed of the coil has the characteristics of a spherical lens, a spherical aberration proportional to the cube of the convergence half angle α occurs. At present, it is extremely difficult to manufacture such an aspherical aberration-free lens by correcting such spherical aberration by disposing a coil. On the other hand, it is empirically said that blurring of an image due to Coulomb interaction is almost inversely proportional to α (from simulation) when the amount of current is constant. This indicates that when the amount of current is constant, the smaller α is, the more the same amount of electrons are confined in a narrower space, so that the Coulomb effect increases. The actual image blur is a combination of the image blur due to the Coulomb effect and the image blur due to spherical aberration, and FIG. 3 shows this as a function of α. Therefore, the best resolution at the desired current value is the half angle of convergence at the point P where the blur of the image due to the Coulomb effect and the blur of the image due to the spherical aberration are substantially equal. Normally, the convergence half angle α is determined under the minimum condition, and the design is made so as to achieve both resolution and throughput.

[0011]

However, the resolution and the current density (throughput) are low under the condition that a sufficient resolution can be obtained, and the resolution is insufficient if a sufficient current density is to be obtained. There is a trade-off relationship. If the spherical aberration can be corrected, α can be further increased, and a higher resolution can be obtained with a desired current amount. Conversely, if the beam has a desired resolution, a larger amount of current can be obtained.

Further, in an apparatus using a charged particle beam such as an electron beam, there is a problem that contamination is accumulated in the apparatus, thereby causing a drift in the electron beam.

The present invention focuses on such a point and prevents the spherical aberration from increasing even if the convergent half angle α is substantially increased, thereby improving the trade-off limit and improving the current density at a high current density. It is an object of the present invention to realize a charged particle beam imaging method and a charged particle beam imaging device capable of obtaining a high resolution, and to improve the throughput of a charged particle beam exposure apparatus using the same without deteriorating the resolution. Another object of the present invention is to reduce the electron beam contamination. These objects are achieved by combinations of the features described in the independent claims. The dependent claims define further advantageous embodiments of the present invention.

[0014]

In order to achieve the above object, a charged particle beam imaging method according to a first embodiment of the present invention is to form a charged particle beam into an image having at least one of an electromagnetic lens and an electrostatic lens. A charged particle beam imaging method for imaging with an image lens, wherein the charged particle beam is divided into child beams by an aperture plate having a plurality of charged particle passage portions, and at least a part of the plurality of child beams is formed into an imaging lens. Is deflected so as to form an image by correcting aberrations. The charged particle passage may be an opening. At least a part of the plurality of sub-beams may be deflected near the pupil plane of the imaging lens.

To achieve the above object, a charged particle beam imaging apparatus according to a second aspect of the present invention is a charged particle beam imaging apparatus for forming an image of a charged particle beam, comprising an electromagnetic lens and an electrostatic lens. An imaging lens having at least one of the following, and imaging a charged particle beam; an aperture plate having a plurality of charged particle passages for dividing the charged particle beam into a plurality of child beams; and at least a part of the plurality of child beams And a correction deflector that deflects the image so as to form an image by correcting the aberration of the imaging lens.

The charged particle passage may be an opening.
The correction deflector may be arranged near the pupil plane of the imaging lens. The aperture plate may be arranged near the pupil plane of the imaging lens. The correction deflector deflects the child beam in a direction toward or away from the optical axis of the imaging lens, and the intensity of the deflection depends on the distance of the child beam from the optical axis. Good. The deflector further deflects the charged particle beam, and the correction deflector deflects the sub-beam in a direction toward or away from the optical axis of the imaging lens, and the intensity of the deflection is determined by the deflector. It may be changed in response to a change in the amount of deflection.

The aperture plate has a first charged particle passing portion including the optical axis of the imaging lens, and at least one second charged particle passing portion around the first charged particle passing portion. The child beam that has passed through the first charged particle passage portion is not deflected, and the child beam that has passed through at least one second charged particle passage portion is deflected in a direction toward or away from the optical axis. Is also good.

The first charged particle passage portion may be substantially circular with the optical axis of the imaging lens as a center. The first charged particle passing unit may have a shape that allows all charged particle beams in which aberration caused by the imaging lens falls within a predetermined allowable range. A grounded electrode may be provided around the first charged particle passage section. The second charged particle passing portion may have a substantially annular shape surrounded by two concentric circles around the optical axis of the imaging lens. The second charged particle passing portion is substantially annular and is surrounded by two concentric circles around the optical axis of the imaging lens, and surrounds at least one second charged particle passing portion.
The difference between the radii of the two concentric circles may be smaller than the diameter of the first charged particle passage portion.

The correction deflector includes a substantially circular correction deflection electrode on the optical axis center side of the imaging lens of the at least one second charged particle passing portion and on the side opposite to the optical axis center. Alternatively, the sub-beam that has passed through at least one second charged particle passing section may be deflected. The aperture plate has a plurality of second charged particle passing portions, and the difference between the radii of two concentric circles surrounding the second charged particle passing portion is smaller as the second charged particle passing portion is farther from the optical axis center of the imaging lens. Is also good. The area of the first charged particle passage may be larger than the area of the second charged particle passage. The aperture plate may include a plurality of second charged particle passages, and the area of the second charged particle passage may be smaller as the distance from the optical axis increases.

[0020] The correction deflector may increase the deflection amount in the second charged particle passage portion farther from the optical axis center of the imaging lens. The correction deflector may be provided on the aperture plate. The correction deflector may be provided on a substrate that does not block the sub-beam split by the aperture plate. An ozone supply unit for supplying ozone may be further provided.

In order to achieve the above object, a charged particle beam exposure apparatus according to a third aspect of the present invention is a charged particle beam exposure apparatus for exposing a sample, wherein the charged particle beam generator generates a charged particle beam. , A shaper for shaping the charged particle beam, a deflector for deflecting the charged particle beam, a sample stage for holding the sample, and at least one of an electromagnetic lens and an electrostatic lens, wherein the charged particle beam is placed on the sample. An imaging lens for forming an image and a correction deflector for deflecting at least a part of the plurality of sub-beams so as to form an image by correcting aberration of the imaging lens are provided. It further comprises a charged particle beam observer for observing the charged particle beam imaged on the sample, and the amount of deflection of the correction deflector is such that the resolution of the charged particle beam observed by the charged particle beam observer is the highest. May be determined. Note that the above summary of the present invention does not list all of the necessary features of the present invention, and a sub-combination of these features may also be an invention.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described through embodiments of the present invention. Not all combinations of the features are necessarily essential to the solution of the invention. 4 and 5 are diagrams illustrating the principle of the present invention. As shown in FIG. 2, the deviation due to the spherical aberration increases according to the half angle of convergence α of the beam.
Therefore, as shown in FIG. 4, an aperture plate 45 is provided on the pupil plane of the imaging lens 42, and the central opening 60 as an example of the charged particle passing portion and the first charged particle passing portion is formed with a convergent half angle with an allowable resolution. A beam A of α is generated.
An opening 61 is provided as an example of a charged particle passing portion and a second charged particle passing portion centered on a position distant from the optical axis on the pupil plane, and the charged particle passing portion and the second charged particle passing portion are provided on opposite sides. An opening 62 is provided as an example of the part so that beams B and C are generated, respectively. The width of the openings 61 and 62 is smaller than the opening 60. Since the beam A passes through the vicinity of a = 0 on the pupil plane, it forms an image at the position x = 0 on the image plane 44. This image has a slight blur of about cr ³ . Beams B and C are respectively a = + R and -R on the pupil plane.
, And -cR ³ and + cR ³ on the image plane, respectively.
An image is formed at a position shifted by only the center. The amount of each blur of the beam B and C is about ^{c ((R + r) 3} -R 3). Note that the pupil plane is a plane on which the stop is placed.

Here, as shown in FIG. 5, the openings 60, 6 are formed on the lower surface of the aperture plate 50 having the same openings as those shown in FIG.
Electrode pairs 51 and 52, 53 and 54, 55 and 56 facing each other are provided corresponding to 1 and 62, respectively, to provide a correction deflector. Electrode pair 5
No voltage is applied to 1 and 52 to ground (ground) level, and the influence of an electric field from the surroundings is shielded. Electrode pairs 53 and 5
4 to generate an electric field in the opening 61,
Shifting the position on the image surface of the beam B only + cR ^3. That is, the beam B is imaged at a position of x = 0 on the image plane.
Similarly, a voltage is applied to the electrode pairs 55 and 56 to form the beam C at the position of x = 0 on the image plane. Thus, the three beams A, B, and C form an image at the position of x = 0 on the image plane. As a result, despite the fact that the half angle of convergence of the optical system was larger than α, the magnitude of blur due to spherical aberration was:
The amount of image blur due to the trajectory of each beam, ie c
((R + r) ³ −R ³ ) and does not increase.

Therefore, in the charged particle beam imaging apparatus according to the present invention, the straight line B in FIG. 3 has been translated to the right, and the position of the point P has been moved to the right along the straight line A and substantially converged. The half angle a is large, but the spherical aberration is small, that is, a high resolution can be obtained at a high current density. Thereby, the limit of the trade-off in the charged particle beam imaging method and the charged particle beam imaging apparatus is improved, and the throughput can be improved without deteriorating the resolution.

Hereinafter, embodiments of the present invention will be described. The electron beam imaging apparatus according to the first embodiment of the present invention has a sectional shape as shown in FIG. FIG. 6 is a plan view showing the structure of the aperture plate 50 used in the first embodiment.
The cross section of Q ′ corresponds to the aperture plate 50 of FIG. FIG.
As shown in FIG. 5, the aperture plate 50 has a substantially circular opening 60 as an example of a charged particle passing portion and a first charged particle passing portion.
Are provided at the center of the optical axis of the imaging lens 42, and openings 61 and 62 as an example of a substantially annular second charged particle passing portion surrounded by a concentric circle centered on the optical axis of the imaging lens 42 are provided therearound. Have. (That is, the openings 61 and 62 in FIG. 5 are connected.) The width of the annular openings 61 and 62 is smaller than the diameter of the substantially circular opening 60 at the center. A part 63 for supporting a part forming the opening 60 is provided in a part of the annular openings 61 and 62. Substantially circular electrodes 51 and 52 are provided around the opening 60 to apply 0V. (That is,
The electrodes 51 and 52 in FIG. 5 are connected. In addition, substantially circular electrodes 54 and 55 are provided on the optical axis center side of the imaging lens 42, which is the inner periphery of the annular openings 61, 62, and the substantially circular electrodes 54, 55 are provided on the outer peripheral side opposite to the optical axis center. Electrodes 53, 56
And a negative voltage −V1 is applied to the electrodes 54 and 55, and the electrode 5
A positive voltage + V1 is applied to 3, 56. This allows
A uniform electric field directed toward the center (optical axis) of the pupil plane is formed in the annular openings 61 and 62, and the electron beam passing through the openings is
The light is deflected in a direction away from the optical axis of the imaging lens 42. If V1 is set appropriately, the electron beams (beams B and C) that have passed through the openings 61 and 62 become x = 0 on the image plane 44.
Is irradiated to the position. Note that V1 once set is maintained without being changed. The setting of V1 is set so that the resolution becomes the best while observing the image formation state of the electron beam on the image plane.

The diameter of the opening 60 near the optical axis is increased and the diameter (width) of the openings 61 and 62 far from the optical axis, that is, the difference between the radii of two concentric circles surrounding the openings 61 and 62 is reduced. By making the magnitude of the aberration in the electron beam passing through each aperture in the image plane approximately the same, an optical system with smaller aberration can be designed.

FIG. 7 is a view showing a cross-sectional shape of the electron beam imaging apparatus according to the second embodiment, and FIG. 8 is a plan view showing a configuration of an aperture plate 70 used therein. The electron beam imaging apparatus according to the second embodiment has a configuration similar to that of the first embodiment, except that an aperture 81 as an example of a substantially circular first charged particle passage portion and a double annular The difference is that openings 82 and 83 are provided as an example of the second charged particle passage section. Portions 84, 85, 86 for supporting the inner portions are provided in some of the annular openings 82, 83. The diameter of the opening 81 is larger than the width of the opening 82, and the width of the opening 82 is larger than the width of the opening 83. Opening 81
An electrode 71 is provided around the, and 0 V is applied. A substantially circular electrode 72 is provided around the inside of the annular opening 82, and a substantially circular electrode 73 is provided around the outside. A negative voltage −V1 is applied to the electrode 72, and a negative voltage −V1 is applied to the electrode 73. A positive voltage + V1 is applied. Further, a substantially circular electrode 74 is provided around the inside of the annular opening 83, and a substantially circular electrode 75 is provided around the outside. A negative voltage -V2 is applied to the electrode 74, and the electrode 75 Is applied with a positive voltage + V2. V1 and V2 are annular openings 82, 8 respectively.
3 is set so that the electron beam passing through 3 is irradiated on the position of x = 0 on the image plane 44. Therefore, V2 is greater than V1.

FIG. 9 is a diagram showing a cross-sectional shape of the electron beam imaging apparatus according to the third embodiment. In the third embodiment, the aperture plate 50 provided with the same correction deflection electrode as that of the first embodiment is used. In addition to this, an opening corresponding to the opening of the aperture plate 50, that is, the opening of the aperture plate 50 is changed. The difference is that an aperture plate 57 having an opening for passing only the passing electron beam is provided on the electron beam incident side with respect to the aperture plate 50. When the front surface of the aperture plate 50 having the correction deflection electrode is irradiated with the electron beam, the correction deflection electrode may be damaged. By providing the aperture plate 57, the irradiation amount of the electron beam to the aperture plate 50 is reduced, and accordingly, the occurrence of damage to the correction deflection electrode is reduced.

In the first to third embodiments, the aperture of the aperture plate is a substantially circular opening at the center and at least one annular opening, but other shapes of openings are also possible. FIG.
FIG. 14 is a plan view of an aperture plate of the electron beam imaging device according to the fourth embodiment. As shown in FIG. 10, the aperture plate of the fourth embodiment has a hexagonal center opening 91 as an example of a first charged particle passing portion centered on a position aligned with the optical axis center of the imaging lens. Around the opening 91, there are six peripheral openings 92A to 92F as an example of a second charged particle passage portion having an area smaller than the center opening 91. Peripheral openings 92A-9
The center of 2F is on a circular locus about the center of the center opening 91. Around the center opening 91, shielding electrodes 93 are provided corresponding to each side, and 0 V is applied. Around the peripheral openings 92A to 92F, correction deflection electrodes 93 to 98 are provided corresponding to each side. -V is applied to the electrode 96 provided on the side in contact with the side of the center opening 91, + V is applied to the correction deflection electrode 93 on the corresponding side, and the two correction deflection electrodes 95 and 9 on both sides of the electrode 96 are applied.
7, a voltage of -0.5 V is applied, and two correction deflection electrodes 94 and 98 on both sides of the electrode 93 are applied with +0.5 V.
The corresponding correction deflection electrodes of the peripheral openings 92A to 92F are connected to each other, and a voltage is applied. As in the first embodiment, the value of V is set so as to obtain the highest resolution while observing the image formation state of the electron beam on the image plane.

The electron beam imaging apparatuses of the first to fourth embodiments have been described above. Next, an electron beam exposure apparatus using such an electron beam imaging apparatus will be described.
FIG. 11 is a diagram showing a configuration of an electron beam exposure apparatus using the electron beam image forming apparatus of the present invention. This electron beam exposure apparatus has a configuration similar to that described with reference to FIG. 1, but omits parts related to the block mask. The same elements as those in FIG. 1 are denoted by the same reference numerals. The electron beam generated by the electron gun 11 is shaped into a rectangular shape by the first shaping aperture 13, and converged by the electromagnetic lens 14 at the position of the second shaping aperture (aperture) 27. An electromagnetic lens 26 is also provided at the second shaping aperture 27. The electron beam that has passed through the stop is once converged by the electromagnetic lens 28, then expanded and incident on the imaging lens 30, and converged on the sample 1. Here, an aperture plate 100 having a correction deflection electrode 101 is provided on the electron beam incident side near the imaging lens 30. The voltage applied to the correction deflecting electrode 101 is set so as to obtain the highest resolution by using an observation device that observes the image forming state of the electron beam on the image plane. In this electron beam imaging apparatus, for example, when the electron beam is irradiated,
Is supplied to a chamber including an electron lens 14 and the like downstream of the aperture plate 13.

By using the electron beam imaging apparatus of the present invention, the spherical aberration does not increase even if the convergence half angle α is substantially increased. Since the convergence half angle α is substantially increased, blurring due to Coulomb interaction is small and spherical aberration is small, that is, high resolution can be obtained at a high current density. This makes it possible to improve the throughput of the charged particle beam exposure apparatus without deteriorating the resolution. In addition, since ozone is supplied, it is possible to remove contamination caused by irradiation of the electron beam, appropriately prevent drift from occurring in the electron beam, and appropriately reduce aberrations generated in the electron beam. Can be reduced.

In the configuration shown in FIG.
The electron beam imaging apparatus of the fourth embodiment shown in FIG. 10 is used as the aperture plate 100 having the first aperture plate 1 and the voltage applied to the correction deflection electrode of each peripheral aperture can be controlled independently. The coma aberration can be corrected (reduced) by changing the voltage applied to the correction deflection electrode according to the deflection amount (not shown). As described above, coma can be made sufficiently small by column design. However, by reducing coma using the electron beam imaging apparatus of the fourth embodiment, the degree of freedom in column design is improved. can do.

FIG. 12 shows a configuration in which a plurality of electron guns 11A to 11C are provided in the configuration of FIG. 11, and the electron beams generated by the respective electron guns pass through the respective apertures of the aperture plate 100. FIG. Thus, by using a plurality of electron guns, the beams 10B and 10B can be used.
Even if the half angle of convergence of C (the incident angle to the sample) is increased, it is possible to obtain a high beam intensity.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the opening is used as an example of the first charged particle passing portion and the second charged particle passing portion. However, the present invention is not limited to this. For example, a silicon nitride film may be used. It is only required that charged particles can pass through.

In the third embodiment, the aperture plate 50 is provided. However, the present invention is not limited to this. For example, the child beam passing through the aperture plate 57 may be provided on an unshielded substrate. You may.

Although the present invention has been described with reference to the embodiment, the technical scope of the present invention is not limited to the scope described in the above embodiment. It is apparent to those skilled in the art that various changes or improvements can be added to the above embodiment. It is apparent from the description of the appended claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

[0037]

As described above, according to the present invention,
Assuming a constant current amount, it is possible to obtain an imaging characteristic in which blur due to Coulomb interaction is small and aberration of the optical system is small, and when a constant blur is assumed, an optical system having a larger current amount is required. It can be designed and the throughput of the electron beam exposure apparatus can be improved. Further, according to the present invention, by appropriately eliminating contamination, drift of an electron beam can be appropriately prevented, and aberration of an optical system can be effectively corrected.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a beam irradiation system of an electron beam exposure apparatus.

FIG. 2 is a diagram illustrating spherical aberration of electron beam imaging by an electromagnetic lens.

FIG. 3 is a diagram illustrating a relationship between a half angle of convergence and a beam blur.

FIG. 4 is a diagram illustrating the principle of the present invention.

FIG. 5 is a view for explaining the principle of the present invention and showing the image forming apparatus of the first embodiment.

FIG. 6 is a diagram showing an aperture plate used in the first embodiment.

FIG. 7 is a diagram illustrating a configuration of an imaging apparatus according to a second embodiment of the present invention.

FIG. 8 is a diagram showing an aperture plate used in the second embodiment.

FIG. 9 is a diagram illustrating a configuration of an image forming apparatus according to a third embodiment of the present invention.

FIG. 10 is a view showing an aperture plate used in a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of an electron beam exposure apparatus using the image forming apparatus of the present invention.

FIG. 12 is a diagram showing a configuration of another electron beam exposure apparatus using the image forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sample (wafer) 2 ... Stage 11 ... Electron gun 12, 14, 20, 22, 26, 28 ... Electromagnetic lens 30, 42 ... Imaging lens (electromagnetic lens) 50 ... Aperture plate 51-56 ... Correction deflection electrode 60 ~ 62 ... Opening

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/30 541B

Claims (25)

[Claims] 1. A charged particle beam imaging method for forming an image of a charged particle beam by an imaging lens having at least one of an electromagnetic lens and an electrostatic lens, wherein the charged particle beam passes through a plurality of charged particle passing portions. A charged particle beam imaging method, wherein the beam is split into sub-beams by an aperture plate, and at least a part of the plurality of sub-beams is deflected so as to form an image by correcting aberration of the imaging lens. . 2. The charged particle beam imaging method according to claim 1, wherein the charged particle passage is an opening. 3. The charged particle beam imaging method according to claim 1, wherein at least a part of the plurality of sub-beams is deflected near a pupil plane of the imaging lens. 4. A charged particle beam imaging apparatus for imaging a charged particle beam, comprising: an imaging lens having at least one of an electromagnetic lens and an electrostatic lens for imaging the charged particle beam; An aperture plate having a plurality of charged particle passage portions for dividing the particle beam into a plurality of sub-beams; and deflecting at least a part of the plurality of sub-beams so as to form an image by correcting aberration of the imaging lens. A charged particle beam imaging apparatus, comprising: 5. The charged particle beam imaging method according to claim 4, wherein the charged particle passage is an opening. 6. The charged particle beam imaging apparatus according to claim 4, wherein the correction deflector is disposed near a pupil plane of the imaging lens. 7. The charged particle beam imaging apparatus according to claim 4, wherein the aperture plate is disposed near a pupil plane of the imaging lens. 8. The correction deflector deflects the child beam in a direction toward or away from the optical axis of the imaging lens, and the degree of deflection of the child beam from the optical axis is The charged particle beam imaging apparatus according to any one of claims 4 to 7, wherein the apparatus is dependent on a distance. 9. A deflector for deflecting the charged particle beam, wherein the correction deflector deflects the child beam in a direction toward or away from an optical axis of the imaging lens, and deflects the child beam. The charged particle beam imaging apparatus according to any one of claims 4 to 8, wherein the intensity of the charged particle beam changes in accordance with a change in the amount of deflection of the deflector. 10. The aperture plate has a first charged particle passing portion including an optical axis of the imaging lens, and at least one second charged particle passing portion around the first charged particle passing portion. The correction deflector does not deflect the sub-beam that has passed through the first charged particle passing portion, and converts the sub-beam that has passed through the at least one second charged particle passing portion toward the optical axis or the optical axis. The charged particle beam imaging apparatus according to any one of claims 4 to 9, wherein the beam is deflected in a direction away from the charged particle beam. 11. The charged particle beam imaging apparatus according to claim 10, wherein the first charged particle passing portion has a substantially circular shape centered on an optical axis of the imaging lens. 12. The charged member according to claim 11, wherein the first charged particle passing portion has a shape that allows passage of all charged particle beams whose aberration caused by the imaging lens falls within a predetermined allowable range. Particle beam imaging device. 13. The charged particle beam imaging apparatus according to claim 11, further comprising a grounded electrode around the first charged particle passage. 14. The apparatus according to claim 10, wherein the second charged particle passing portion is substantially annular surrounded by two concentric circles centered on an optical axis of the imaging lens. A charged particle beam imaging apparatus according to claim 1. 15. The second charged particle passage section is substantially annular and surrounded by two concentric circles around the optical axis of the imaging lens, and surrounds the at least one second charged particle passage section. 2
The charged particle beam imaging apparatus according to claim 11, wherein a difference between radii of the two concentric circles is smaller than a diameter of the first charged particle passage portion. 16. The at least one correction deflector comprises:
A substantially circular correction deflection electrode on the optical axis center side of the imaging lens of the two second charged particle passing portions and on the opposite side of the optical axis center;
16. The charged particle beam imaging apparatus according to claim 14, wherein the correction deflection electrode deflects the sub-beam that has passed through the at least one second charged particle passage. 17. The aperture plate has a plurality of second charged particle passages, and the two charged particle passages that are more distant from the optical axis center of the imaging lens surround the second charged particle passages. 17. The difference in radius between concentric circles is small.
A charged particle beam imaging apparatus according to any one of the above. 18. The charged particle beam imaging apparatus according to claim 10, wherein an area of the first charged particle passage is larger than an area of the second charged particle passage. 19. The apparatus according to claim 10, wherein the aperture plate has a plurality of the second charged particle passages, and an area of the second charged particle passage is smaller as the distance from the optical axis increases. A charged particle beam imaging apparatus according to claim 1. 20. The charged particle beam forming apparatus according to claim 17, wherein the correction deflector increases the deflection amount as the second charged particle passage portion is farther from the optical axis center of the imaging lens. Imaging device. 21. The charged particle beam imaging apparatus according to claim 4, wherein the correction deflector is provided on the aperture plate. 22. The charged particle beam imaging according to claim 4, wherein the correction deflector is provided on a substrate that does not block the sub-beam split by the aperture plate. apparatus. 23. The charged particle beam imaging apparatus according to claim 4, further comprising an ozone supply unit for supplying ozone. 24. A charged particle beam exposure apparatus for exposing a sample, comprising: a charged particle beam generator for generating a charged particle beam; a shaper for shaping the charged particle beam; and a deflection unit for deflecting the charged particle beam. A sample stage for holding the sample, an imaging lens having at least one of an electromagnetic lens and an electrostatic lens, and forming an image of the charged particle beam on the sample; and at least one of the plurality of sub-beams. A charged particle beam exposure apparatus, comprising: a correction deflector that deflects the unit so as to form an image by correcting aberration of the imaging lens. 25. A charged particle beam observer for observing the charged particle beam imaged on the sample, wherein a deflection amount of the correction deflector is the charged particle observed by the charged particle beam observer. 25. The charged particle beam exposure apparatus according to claim 24, wherein the resolution of the beam is determined to be the highest.