JP2712487B2 - Electron beam exposure apparatus and electron beam exposure method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Table of Contents] Overview Industrial application field Conventional technology Problems to be solved by the present invention Means to solve the problem Actions Embodiment (a) Description of electron beam exposure apparatus based on the present invention (First
(Figure) (b) Eddy current generation mechanism in the moving stage (No. 7)
(FIG. 8, FIG. 8) (c) Description of the magnetic objective lens based on the present invention (FIG. 3 to FIG.
FIG. 6) Effects of the Present Invention [Overview] The present invention relates to an improvement of a magnetic objective lens of an electron beam exposure apparatus that irradiates an electron beam on an object mounted on a stage that moves continuously in a predetermined direction. A magnetic objective lens having a lower pole piece provided opposite to an object to be irradiated, for preventing unnecessary magnetic flux from a magnetic objective lens from leaking in the direction of a stage in order to improve beam convergence. The lower pole piece has an opening corresponding to a predetermined scanning space of the electron beam scanned in a direction perpendicular to the moving direction of the irradiation object. The bore allows the electron beam to pass through, and most of the magnetic flux in the magnetic objective lens is blocked by the other part of the lower pole piece except for the bore. It is characterized in that to prevent the motor has the advantage that this arrangement avoids the generation of eddy currents in the stage caused by the leakage flux can be maintained good convergence of the electron beam.

[Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron exposure apparatus used for electron beam lithography, and more particularly to an electron exposure apparatus which avoids generation of an eddy current based on a leakage magnetic flux generated in a continuously moving stage mounted with a workpiece. The present invention relates to a magnetic objective lens capable of maintaining good convergence of the electron beam.

An electron beam exposure system is a large-scale semiconductor device,
It is widely known as a method of forming fine circuit patterns of LSI. As the integration density of LSIs has increased, conventional optical lithography techniques have reached their limits, and higher precision techniques such as electron beam lithography have been required. A key feature of electron beam lithography is its high resolution. The problem of light diffraction inherent in optical lithography is
It is solved by an electron beam of 10 to 20 Kv. This is because the equivalent wavelength of this electron beam is 1 ° or less, which is much shorter than the wavelength of ultraviolet light. Further, the pattern formation is controlled entirely by an electronic computer electron beam exposure apparatus, and the process flow is short. Therefore, the mechanization of the manufacturing process of the related LSI is easy, and it is suitable for mass production from the viewpoint of yield and production stability.

Electron beam lithography is classified into two types, an electron beam projection type and an electron beam scanning type, and the present invention relates to the latter type. In electron beam scanning lithography, the circuit pattern consists of a finely focused electron beam,
Deflection and ON / OFF are controlled by an electronic computer.
The electron beam scanning mechanism includes an electron beam forming means for forming an electron beam from an electron source into an electron beam having a round or narrow cross section, and an electron beam for deflecting the electron beam and scanning the electron beam by a raster or vector scanning method. It comprises beam deflecting means and pattern generation control means for controlling the movement of the stage placed on the workpiece by controlling the electron beam deflecting means and drawing a required circuit pattern on the workpiece. Hereinafter, the workpiece is described as a semiconductor wafer.

Generally the scanning span is 2mm to avoid lens aberration
Limited to the rank. Therefore, the entire surface of the wafer is divided into a number of sections, and the wafer is sequentially exposed to one section. Naturally, the wafer or the stage is moved in synchronization with the scanning of the electron beam. The stage is usually movable in the XY directions in a horizontal plane. There are two types of movement.

One is step. and. In the repeat method, an element pattern is drawn by irradiating an electron beam into a rectangular section area on a wafer. When the pattern formation in one of the divided areas is completed, the wafer moves and the pattern formation in the next divided area is started.

Another method is a continuous moving stage method, for example, B
EBES (electron beam e)
The present invention relates to a method adopted in an xposure system. In this method, the electron beam is scanned by a raster method, and the stage moves continuously, usually in a direction orthogonal to the main scanning direction. The advantage of this method is that the movement of the stage and the scanning of the electron beam are performed simultaneously in parallel, and time is saved. On the other hand, step. and. In the repeat method, when the stage stops, mechanical vibration occurs on the stage, and it takes time to converge the mechanical vibration until the next stage of scanning of the electron beam is started, so that the electron beam exposure time becomes longer. In our experience, this waiting time amounts to 0.3 seconds. 2mm on 4 inch wafer now
Assuming that the electron beam exposure is performed in the sectioned area, the total waiting time is 520 seconds per wafer, which accounts for about 70% of the electron beam exposure time of the entire wafer. Therefore, LSI
It seems that the continuous moving stage method is more suitable for mass production.

[Conventional technology]

However, this continuous moving stage system also has disadvantages. That is, when a part of the magnetic flux generated in the magnetic objective lens, that is, the leakage magnetic flux intersects the moving stage, an eddy current is generated, and the eddy current generates a new magnetic flux, which is projected onto the wafer. The convergence of the electron beam is disturbed, and the resolution for forming the circuit pattern is reduced. As will be described in detail later, in connection with the present case, generally, the magnetic objective lens of the magnetic lens system of the conventional electron beam exposure apparatus has a circular bore in the pole piece which is one of its components. It should be noted. In order to suppress the aberration of the lens, all the magnetic lens systems are designed so that the central axis is a rotationally symmetric axis, so that the shape of the bore is circular.

Since the circular bore is much larger than the scanning space of the electron beam, there is no hindrance to the passage of the electron beam, but the strong magnetic flux generated in this magnetic objective lens passes through this bore. It is irradiated to the moving stage and disturbs the convergence of the related electron beam as described later.

Further, in order to reduce the lens aberration of the magnetic lens system, particularly the magnetic objective lens, it is desirable that the electron beam is controlled to always run on the axis of the magnetic objective lens. Further, when the wafer is irradiated with the electron beam, it is desirable that the electron beam be irradiated perpendicularly to the surface of the wafer. This is because, when the electron beam is irradiated perpendicularly to the wafer surface, even if there are some irregularities or tom-like steps on the wafer surface, deformation of the drawn circuit pattern can be avoided.

In order to achieve the above two objectives, the technology of moving the optical axis of a magnetic objective lens in parallel in the radial direction in accordance with the deflection of an associated electron beam has been developed as a magnetic objective lens (VAL) having a variable optical axis. Developed by International Business Equipment Company (IBM) and used in its EL3 system. The technique is disclosed in U.S. Patent No. 4,376,249, published 1983.03.08.

The VLA magnetic objective lens has two sets of deflection coils and two sets of compensating deflection coils (or optical axis shift coils). These coils are electrically connected in series and are simultaneously activated. Be transformed into The optical axis of the magnetic objective lens is shifted parallel to the original optical axis by the compensation coil, and is double-deflected by two sets of deflection coils in a direction perpendicular to the wafer surface, that is, parallel to the optical axis of the magnetic objective lens. The electron beam is controlled so as to always coincide with the optical axis of the shifted magnetic objective lens. Since the electron beam is always on the optical axis of the magnetic objective lens, coma and chromatic aberration are effectively eliminated.

On the other hand, the wafer is mounted on a stage that can move in the XY directions. When the stage includes a metal layer,
When the leakage magnetic flux emitted from the compensation coil at the lowermost part of the magnetic objective lens passes through the wafer and reaches the stage, an eddy current is generated in the stage. As described above, since the pole piece below the magnetic objective lens has a circular bore, it is inevitable that this leakage magnetic flux will enter the stage, and once the stage moves, eddy current will always occur in the stage. This impairs the electron beam focusing action of the magnetic objective lens.

In order to remove the above-mentioned lowermost compensation coil and to cut off the influence of the external magnetic flux including the above-mentioned eddy current, IBM
(Variable axis immersion lens) was developed in 1985.
10.01 is disclosed in U.S. Patent No. 4,454,846. VAIL is provided with a lower pole piece without ferrite bore, and the wafer to be treated is located on the lower pole piece and wrapped in a magnetic objective lens. The wafer is immersed in the magnetic flux of the magnetic objective lens, and the pole piece of the magnetic objective lens has the effect of a magnetic cage confining the magnetic flux. Since the lower pole piece is made of ferromagnetic ferrite, the magnetic flux in the magnetic objective lens is perpendicular to the pole piece. As a result, the electron beam that has entered the magnetic objective lens is also projected perpendicularly to the pole piece, that is, perpendicularly to the wafer, so that pattern distortion can be reduced. But VA
If an attempt is made to move the wafer continuously even in the IL structure, eddy currents are immediately generated in the lower pole piece, causing the above-mentioned problem. Therefore, the wafer cannot be used in a continuous stage electron beam exposure apparatus such as the present invention. Absent.

For VAL and VAIL, the HCPfeiffe
MICROCIRCUIT ENGINEERING.ISBN, 012 345 750 5,
On pages 72-81.

[Problems to be solved by the invention]

An object of the present invention is to improve the disadvantages of the magnetic objective lens of the conventional electron beam exposure apparatus described in detail above. That is, since the lower pole piece bore of the conventional magnetic objective lens is formed in a circular shape symmetrical with respect to the rotation axis, the magnetic flux generated inside the magnetic objective lens leaks outside from the circular bore and the wafer Improved magnetic objective lens to prevent eddy currents from being generated in the stage when the stage moves while intersecting with the stage on which the optics are mounted, and thereby generating harmful magnetic flux that impairs the convergence of the electron beam. It is.

[Means for solving the problem]

An electron beam exposure apparatus according to the present invention comprises: an electron emitting device; an electron converging device for converging electrons emitted from the electron emitting device to form an electron beam; an electron beam deflecting device for deflecting the electron beam; An electron beam exposure apparatus comprising a magnetic objective lens having a compensating means and a movable stage on which an object to be irradiated with an electron beam is mounted. , An upper pole piece made of a magnetic material and a lower pole piece made of a magnetic material arranged to face the irradiation object and inducing this magnetic flux. The lower pole piece corresponds to the scanning space of the electron beam. The slit has a slit-shaped bore formed in the scanning direction of the electron beam and capable of passing the electron beam. It is configured.

[Action]

In the electron beam exposure apparatus according to the present invention, the magnetic objective lens includes a coil for generating a magnetic flux, an upper pole piece made of a magnetic material, and a magnetic material arranged to face the irradiated object and inducing the magnetic flux. A lower pole piece, which is formed in a portion corresponding to the scanning space of the electron beam, and which is formed by extending in the scanning direction of the electron beam and capable of passing the electron beam. Since the electron beam is controlled by the central computer, the electron beam controlled by the central computer can scan the surface of the irradiation object facing the lower pole piece, and the leakage magnetic flux leaking from the magnetic objective lens causes a magnetic flux other than the bore of the lower pole piece. Since it is shielded by the area, the eddy current generated on the stage on which the irradiation object is mounted and moved can be reduced, and the convergence of the electron beam is prevented. It is possible to greatly suppress the use.

〔Example〕

(A) Description of Electron Beam Exposure Apparatus Based on the Present Invention An electron beam exposure apparatus according to the present invention, except for its magnetic objective lens, was described by Yasuda, the inventor of the present invention, as an electronic exposure system and an operation method thereof. No. 4,362,942, published on Dec. 7, 1982, and is identical to the electron beam exposure apparatus. In the present invention, a magnetic objective lens is improved. The device is a step. and. Although it can be used for either the repeat method or the continuous stage movement method, the present invention is limited to the latter method.

FIG. 1 shows an electron beam exposure apparatus according to an embodiment of the present invention. Electrons emitted from the electron gun G are converged by the three converging lenses 4 and the magnetic objective lens 9 to form an electron beam B. The electron beam B is applied to the magnetic objective lens 9
Is projected onto a desired position of the semiconductor wafer 10 mounted on the stage 11 movable in the XY directions. Stage 1
1, thus the wafer 10 is continuously moving in the X direction. Of course, the X, Y, and Z directions are orthogonal to each other.

Under the control of the pattern signal of the central computer CPU 12, the electron beam B is turned on and off by a beam blanking means (not shown), cut by the rectangular aperture 1, deflected by the deflecting plate 2, and further deflected by another rectangular aperture. 3 and shaped into a rectangular electron beam.

The rectangular electron beam B shaped as described above corresponding to the pattern signal is double-deflected by the two sets of deflection coil pairs 8a and 8b and the compensation coil (axis shift coil) 8c, and then on the surface of the wafer 10. Is projected perpendicularly to the center point of the target first segmented area of, for example, 100 μm square. Thereafter, the electron beam B is deflected by the sub-deflecting plate 5 to form a pattern composed of a combination of several rectangular patterns. The sub-deflection plate 5 is controlled by static electricity. Numerals 6 and 7 indicate a stigmator coil and a focusing coil, respectively.

After the pattern formation of the first sectioned area is completed, the electron beam B is moved and projected to the center point of the adjacent second sectioned area, and subsequently, the pattern formation of the area is performed in a similar manner under the control of the central computer CPU12. . In this way, for example, pattern formation of each of the 20 segmented regions arranged in the Y direction is completed. That is, the pattern formation of the ribbon-shaped region having a width of 100 microns and a length of 2 mm is completed. Therefore, it can be said that the Y direction is the main scanning direction. Hereinafter, the scanning direction refers to the above-described main scanning direction.

Thereafter, the electron beam B is returned to a new section area adjacent to the first section area in the X direction. In this manner, the entire region of the stripe-shaped region extending in the X direction with a width of 2 mm on the wafer 10 is irradiated with the electron beam B, for example. Next, the electron beam projection is moved to the adjacent stripe-shaped region having a width of 2 mm, and the above-described steps are repeated.

In the above example, the scanning of electron beam B is limited to a 2 mm span in the Y direction and another narrow span of 100 microns in the X direction. Since the above-described scanning span is extremely long in the Y direction and short in the X direction, the scanning space of the electron beam B is in an elongated area extending in the Y direction. The cross section of the above-mentioned scanning space perpendicular to the projection direction of the electron beam B has an elongated rectangular shape extending in the Y direction with a width of 2 mm and 100 microns in the above example.

The stage 11 has an extremely robust and precise mechanism, and can be moved in both X and Y directions by a motor (not shown).
The wafer 10 mounted on the stage 11 can move accurately and stably according to the pattern signal. On the other hand, since the stage 11 is continuously moving in the X direction, the movement of the wafer 10 mounted thereon is a superposition of the movement by the pattern signal and the continuous movement. The actual spatial coordinate position of the wafer 10 on the stage 11 is detected by the laser interferometer 17 and is constantly fed back to the central computer CPU 12 so that the projection position of the electron beam B is continuously adjusted so as to correspond to the pattern signal at that moment. Has been corrected. Other components, such as coils 6,7, memories 13,16, registers 14, adders 15, converters 18, subscraptors 19, and amplifiers 21 and 24 are described in Yasuda U.S. Pat. Here, it is omitted.

(B) Mechanism of Generating Eddy Current in Moving Stage Before proceeding, the mechanism of generating eddy current generated in the stage by the magnetic flux crossing the moving stage and the harmful effects thereof will be described in detail.

FIG. 7 is a sectional view of a main part showing a structure of a magnetic objective lens of a conventional electron beam exposure apparatus. The magnetic objective lens is configured to be axially symmetric about an axis A extending in the Z direction, and surrounds an upper pole piece 101a, a lower pole piece 101b, and a pole piece 101a, 101b opposed thereto with a space 101c therebetween. A coil 105 that generates a magnetic flux, a shield 105 surrounding the coil 102 and preventing the magnetic flux from leaking out of the magnetic objective lens 105, X
A stage 107 is movable in the −Y direction, and a coil 104 deflects the electron beam B in the Y direction. The stage 107 has a complicated mechanism for driving the stage 107, but is represented by a simple plate for simplicity.

The magnetic flux generated by the coil 102 is pole pieces 102a, 102b
And radiates into the inside of the magnetic objective lens to form a magnetic lens near the space 101c. The magnetic flux leaking out of the magnetic objective lens is blocked by the magnetic shield 105, and the magnetic flux radiated inside terminates on the inner walls of the pole pieces 102a and 102b. Thus, the magnetic flux is supposed to be confined in the magnetic objective lens in principle, but the two pole pieces 102a, 102b are formed with circular bores 103a, 103b for passing the electron beam B. As a result, the magnetic flux leaks downward through the bore 103b and crosses the stage 107.

The stage 107 is formed of, for example, an electrical insulator such as a ceramic, but its surface is covered with a metal deposition layer to prevent accumulation of electric charge. As a result, when the stage 107 moves due to the intersecting magnetic flux, an eddy current is generated in the metal layer. Furthermore, since the drive mechanism provided below the stage 107 is usually made of metal, when the mechanism moves, an eddy current is generated here as well, and this eddy current generates harmful magnetic flux that hinders the convergence of the electron beam B. Generate a new one.

FIG. 8 is a partially cutaway perspective view of the conventional magnetic objective lens shown in FIG. 7, in which only the stage 107 and the pole pieces 101a and 101b are shown, and the wafer is not shown. When scanning is not performed, the electron beam B is radiated to the mid-positive point P0. When the scanning operation starts, the electron beam B scans back and forth between the points P1 and P2. As shown in FIG. 8, the leakage magnetic flux 111 (shown by a dotted line) is a circular bore 103.
It leaks from b and crosses the stage 107. As mentioned earlier,
The reason why the shape of the bore 103b is circular is that an electron beam B (shown by a solid line) is passed to scan in the X and Y directions, and that the magnetic objective lens is designed to be rotationally symmetric about the axis A and the aberration of the lens. This is the format adopted with the intent to remove. When the stage 107 moves in the X direction as shown by the arrow 107a, the portion 106 where the magnetic flux crossing the stage 107 increases
a and a reduced portion 106b occur. Such a partial change in magnetic flux density causes the eddy currents 112 to rotate in opposite directions.
a and 112b are generated in portions 106a and 106b, respectively. As a result, a new magnetic flux 110 reaching the portion 106b from the portion 106a is generated while intersecting the path of the electron beam B.

Due to this new magnetic flux 110, the electron beam B is deflected in the Y direction. Strictly speaking, the electron beam B is deflected not only in the Y direction but also in the X direction, albeit in a small amount. The deflection of the electron beam B by the magnetic flux 110 is outside the control of the central electron beam exposure apparatus CPU, and in any case, the convergence of the electron beam B is disturbed and the wafer (not shown)
This results in distortion of the circuit pattern drawn above. The present invention is to reduce the eddy current generated in the stage 107 described above.

(C) Description of the magnetic objective lens according to the present invention FIG. 2 is a sectional view of a main part of the magnetic objective lens according to the present invention, and FIG. 3 is a plan view of a lower pole piece of the magnetic objective lens shown in FIG. It is. The magnetic objective lens shown in FIGS. 2 and 4 has a rotational axis symmetrical structure about the central axis A.

The magnetic objective lens according to the present invention comprises an upper pole piece
31a, a lower pole piece 31b, a coil 90, and an outer shield 50. Further, a pair of deflection coils 34a and 34b for deflecting the electron beam B twice (twice) in the Y direction, and a compensation coil 34 for moving the lens axis of the magnetic objective lens in parallel.
c is provided inside the pole piece 31a. The lower pole piece 31b faces a wafer (not shown) mounted on the stage 11. The stage 11 is a ceramic plate whose surface is covered with a metal layer as in the conventional case.
It is movable in the XY directions by a drive mechanism (not shown).

Most of the structure of the magnetic objective lens shown in FIG. 2 is the same as that of the conventional magnetic objective lens shown in FIG. 7, but as is clear from the plan view of FIG. The shape of the bore is completely different from the conventional example. That is, the bore 33b according to the present invention shown in FIG. 3 is an elongated rectangle or a slit having a width W and a length L, whereas the
The conventional pole piece bore 103b shown in the figure is circular.
The size, position and arrangement direction of the bore 33b are such that the bore 33b allows the passage of the electron beam B during scanning, and at the same time, the large lower pole piece 31 allows a large part of the magnetic flux in the magnetic objective lens.
It is determined not to be interrupted by b and to cross the stage 11. For example, if the specified scanning span is 2 mm and the segmented area is 100
For micron square dimensions, the above dimensions of bore 33b are L = 20
4040 mm, L = 4〜6 mm. The dimension of the slit-shaped bore 33b is larger than that of the scanning space is the lower pole piece
This is because ferrite which is ferromagnetic and has small residual magnetic hysteresis but has low machinability is used as the material of 31b.

FIG. 4 is a perspective view including a partial cross-sectional view of a main part of the magnetic objective lens shown in FIG. 2, and shows a positional relationship between the electron beam B and the main part of the magnetic objective lens. The electron beam B projected from above is double-deflected by the coil pairs 34a and 34b, and is parallel to the axis A and shifted from the axis A so that the lower pole piece 31 is displaced.
Project on b. Magnetic objective lens is coil 90, pole piece
The electron beam B is shaped by 31a and 31b, and is shifted by the compensating coil 34c so as to coincide with the path of the electron beam B deflected simultaneously with the deflection of the electron beam B. The control of each coil described above is performed by a central computer (CP
U).

As a result, the electron beam B passes through the slit-like bore 33b and is projected vertically onto a wafer (not shown) without being subjected to aberration of the magnetic objective lens. In view of the above points, it can be said that the same effect as that of the conventional VAL or VAIL magnetic objective lens can be obtained.

However, in the electron beam exposure apparatus according to the present invention, since the stage 11 is constantly moving in the X direction as described above, it is necessary to pay attention to the magnetic flux crossing the stage 11.

FIGS. 5 (a) and 5 (b) show slit-shaped bores, respectively.
FIG. 33B is a partially enlarged cross-sectional view of the magnetic objective lens 33b in the X direction and the Y direction, showing a distribution state of the magnetic flux 40 radiated from inside the magnetic objective lens. Most of the magnetic flux 40 is intercepted and absorbed by the lower pole piece 31b.

On the other hand, of the magnetic flux 40 projected on the bore 33b, an extremely small amount of the magnetic flux 40a passes through the slit-shaped bore 33b and is projected on the wafer 10, and a considerable part of the magnetic flux 40 is a pole piece 31
FIG. 5 (b) shows the absorption on the side wall of the bore 33b perpendicular to the surface of b. This is a unique function of the slit-like bore 33b formed according to the present invention.

In the above description, the fourth coil, that is, the second compensation coil is not provided, but the longitudinal bore 33b shown in FIG.
A compensating coil for deflecting the electron beam B in the direction of deflection, that is, in the Y direction, can be provided on the side wall 33d.

FIG. 6 is a perspective view showing the above-mentioned structure, and shows a pattern in which a compensation coil pair 35 is provided on a longitudinal side wall 33d of a slit-like bore 33b provided in a lower pole piece 31b. The compensation coil 35 is made of several turns of copper wire,
Driven in synchronization with the deflection of the electron beam B as described above,
The convergence of the electron beam B is further promoted.

In each of the above-described embodiments, the electron beam B is deflected in a plane including the optical axis X of the magnetic lens system in one direction, for example, the Y-axis direction, that is, the electron beam B performs the scanning operation. It is obvious to those skilled in the art that the present invention is applicable even when the scanned area is two-dimensionally expanded in the two X and Y directions. That is, the shape of the opening of the bore of the lower pole piece is formed to be as narrow as the processing technology allows, including the area to be scanned, and the electron beam is projected through the bore while the magnetic objective lens is being formed. It is possible to form a magnetic objective lens structure in which the magnetic flux projected from the inside is blocked by the lower pole piece as much as possible, thereby reducing the eddy current generated in the moving stage and improving the convergence of the electron beam.

In each of the above-described embodiments, the continuous stage moving method in which the stage is constantly moved in one direction during the exposure of the electron beam exposure apparatus has been described. Obviously, the present invention can be applied to a beam exposure method. That is, as long as the stage moves, whether it is continuous or intermittent, eddy currents are generated in the stage if the magnetic flux crosses the stage. This is because the eddy current can be effectively reduced by using the shape of the bore provided in the lower pole piece according to the present invention.

〔The invention's effect〕

As is apparent from the above description, the magnetic flux leaking from the magnetic objective lens used in the magnetic lens system of the electron beam exposure apparatus according to the present invention toward the object to be exposed such as a semiconductor wafer is minimized. Because the suppression is reduced,
Eddy currents generated in the stage on which the object is mounted as the stage moves are significantly reduced. As a result, the harmful magnetic flux generated by the eddy current, which is out of the control of the central computer, is reduced, and the conventional problem that the convergence of the electron beam focused by the magnetic lens system is reduced is solved. With the beam exposure apparatus, a very accurate and high-resolution circuit pattern can be easily drawn on a semiconductor object such as a wafer.

[Brief description of the drawings]

FIG. 1 is an electron beam exposure apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of a main part of a magnetic objective lens according to the present invention, and FIG. 3 is a lower pole piece of the magnetic objective lens shown in FIG. FIG. 4 is a perspective view including a partial cross-sectional view of a main part of the magnetic objective lens shown in FIG. 2, and FIGS. 5 (a) and (b) are slit-shaped bores 33, respectively.
b is a partially enlarged cross-sectional view in the X and Y directions, FIG. 6 is a perspective view showing the structure of a compensation coil provided on the side wall of the bore 133b, and FIG. 7 is a view of a magnetic objective lens of a conventional electron beam exposure apparatus. FIG. 8 is a partial cutaway perspective view of the conventional magnetic objective lens shown in FIG. 7 showing the structure. In the figure, 8a, 8b, 34a, 34b ... deflection coil, 8c, 34c, 35 ... compensation coil, 10 ... semiconductor wafer, 11, 107 ... stage, 31a, 101
a ... Upper pole piece, 31b, 101b ... Lower pole piece, 33b, 103b ... Bore, 40, 40a ... Magnetic flux, 50, 105 ... External shield, 90, 102 ... Lens coil, A ... Magnetic lens The system optical axis, B... Indicates the electron beam.

Claims (5)

(57) [Claims] An electron emitting means, an electron converging means for converging electrons emitted from the electron emitting means to form an electron beam, an electron beam deflecting means for deflecting the electron beam, and an electron beam compensating means. An electron beam exposure apparatus comprising a magnetic objective lens and a movable stage on which an object to be irradiated with an electron beam is mounted, wherein the magnetic objective lens includes a coil for generating a magnetic flux, and a magnetic material. An upper pole piece and a lower pole piece made of a magnetic material arranged to face the irradiation object and inducing the magnetic flux, wherein the lower pole piece corresponds to a portion corresponding to a scanning space of the electron beam. An electron beam having a slit-shaped bore formed in the scanning direction of the electron beam and capable of passing the electron beam. Exposure apparatus. 2. An electron beam exposure apparatus according to claim 1, wherein a scanning direction of said electron beam and a moving direction of said stage are orthogonal to each other. 3. An electron beam exposure apparatus according to claim 1, wherein said bore provided in said lower pole piece has a rectangular shape extending in a scanning direction of said electron beam. 4. An electron beam exposure apparatus according to claim 1, wherein said object to be irradiated is a semiconductor wafer. 5. An opening is formed in said lower pole piece provided opposite to said irradiation object so as to allow said electron beam to pass in correspondence with said limited electron beam scanning space. An electron beam using an electron beam exposure apparatus that has a bore, scans an electron beam in a limited scanning space extending in at least one direction, and irradiates the object beam mounted on a moving stage with the electron beam. An exposure method, wherein the lower pole piece excluding the bore forming region includes:
An electron beam exposure apparatus, wherein unnecessary magnetic flux leaking from the magnetic objective lens is shielded.