JP2000090866A - Electron gun, electron beam generating method by electron gun, and exposing device using electron gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the fine adjustment of the current angular density of the electron beam passing through an aperture for use by applying a magnetic field to the electron beam on a beam axis generated by a negative electrode inside of a vacuum container, and accelerating the beam with a positive electrode so as to form a passage so as to generate an electric field to be converged by an electron lens. SOLUTION: A magnetic pole unit 14 applies the magnetic field to the electron beam generated by an emitter 3 inside of a vacuum container, and an anode electrode 7 accelerates the beam in a beam axis 2 direction so as to form a passage. An electron lens electrode 6 converges the accelerated electron beam onto the beam axis 2 by generating the electric field, and the electron beam is emitted from a blanking aperture 8. A permanent magnet 10 and an electromagnetic coil 11 of the magnetic pole unit 14 are arranged in a closed space formed by an outside magnetic pole 12, an inside magnetic pole 13 and non-magnetic material 15a, 15a, and a tip of the magnetic pole is connected to an extractor electrode 5 through an insulating material 16. With this structure, the electron gun 1 is mounted and remarkably accurate processing of the fine patterns is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for emitting thermoelectrons and electric field electrons from a cathode, and to an electron gun such as an electron beam lithography system or an electron beam lithography system using a semiconductor fine pattern exposure system (EB exposure system). The present invention relates to an exposure apparatus using a beam.

[0002]

2. Description of the Related Art In a fine pattern exposure apparatus used for manufacturing a semiconductor, high luminance is required to obtain a fine pattern.

[0003] Therefore, it is necessary to irradiate the wafer with a high current density, but it is desirable that the irradiation angle be small due to the aberration of the electron lens electrode.

[0004] The brightness is the electron current density (current angular density) per unit area. However, since the value of this brightness cannot be increased by the lens of the electron optical system after the electron gun,
It is important that the electron gun has high brightness. A major factor that lowers the brightness of the electron gun is the aberration of the electron lens electrode in the electron gun.

The aberration of the electron lens electrode can be roughly classified into
(A) geometric aberration (spherical aberration, axial asymmetric aberration), (b) diffraction aberration, and (c) chromatic aberration. Of these aberrations, reduction of chromatic aberration (chromatic aberration is proportional to the energy width) is particularly important as fine processing is performed.

[0006] Chromatic aberration occurs when a change occurs in the acceleration voltage of the anode of the electron gun and the lens current of the electron lens electrode. Therefore, in order to reduce chromatic aberration, both the acceleration voltage power supply and the electron lens electrode excitation current power supply need to have high stability.

An electron gun used in an EB exposure apparatus or the like is a thermoelectron using a conventional LaB6 (lanthanum hexaboride) as a FEG (field emission electron gun) / TFEG (thermal field emission electron gun) in terms of performance. Energy width is 1 compared to a radiation gun
/ 5, which is preferable performance.

However, the tip of the emitter (cathode) of the field emission type electron gun and the thermal field emission type electron gun is formed in a very small needle shape (radius of 1 μm or less), and the electrons radiate from the cathode and diverge. I do. For this reason, in order to obtain a large current, it is necessary to collect electron beams having a large aperture angle, and the electron beam diameter increases due to the spherical aberration of the electron lens electrode system of the electron gun, and the brightness decreases.

As a countermeasure, a magnetic field immersion electron gun is sometimes used. The magnetic field immersion electron gun is a system in which a magnetic field is superimposed on a bipolar region including an emitter (electron emission source) to converge a beam and reduce aberration of an electron lens electrode.

FIG. 5 is a block diagram showing the configuration of a field emission type electron gun disclosed in Japanese Patent Application Laid-Open No. 9-7538. The electron gun 31 moves the emitter 3 along the beam axis 32.
3. A suppressor electrode 34, an extractor electrode 35, an electron lens electrode 36, and an anode electrode 37 are arranged, and the magnetic field generated by the coil 44 is guided by the magnetic pole. Further, a strong magnetic field is applied to the tip of the emitter 33 by incorporating the extractor electrode 35 at the tip of the magnetic pole.

Further, the electron gun comprises an emitter, an extractor electrode (first anode electrode), and second and third anode electrodes, and a magnetic field generated by the coil is transmitted from the extractor electrode (first anode electrode) to Technology applied to the third anode electrode part (Improvement
of Beam Characteristicsb
y Superimpossing a Magneti
c Fieldon a Field Emissio
n Gun "Electron Microsc."
Vol. 38, no. 2, 83-94, 1989).

However, in this technique, the coil and the magnetic pole have a different structure from the preceding electrode, and no integration is performed. Therefore, the position of the magnetic pole is away from the electron beam axis by several mm to several tens mm, and the magnetic field that can be applied is several tens m.
It is about T (millitesla).

In the technique disclosed in Japanese Patent Application Laid-Open No. Hei 6-139076, an emitter, a suppressor electrode, an extractor electrode, and an anode electrode are used, and the effect of the lens is achieved by a condenser lens using a coil. In this case, a part of the barrel of the electron gun is integrated with the magnetic pole. This is an attempt to make the magnetic pole as close to the beam axis as possible.

According to the technique disclosed in Japanese Patent Application Laid-Open No. 6-162979, the electron gun is composed of an emitter, a suppressor electrode, an extractor electrode, an electron lens electrode, and an anode electrode.
It is applied to the extractor electrode, electron lens electrode, and anode electrode. At this time, since the coil and the magnetic pole have a different configuration from the previous electrode and are located outside the lens barrel, the magnetic pole position is several mm from the electron beam axis as in the case described above.
The magnetic field that can be applied is about several tens mT (millitesla). In this case, the magnetic pole and the electrode are not integrated.

The applicant has previously filed Japanese Patent Application No. 10-1649.
No. 58 has filed an application in which the magnetic pole unit is constituted by either a permanent magnet or an electromagnetic coil. FIG. 6 shows a configuration using a permanent magnet and a configuration in which a magnetic pole and an extractor are integrated, and a potential distribution Φ and a magnetic field distribution B generated on a beam axis corresponding to the configuration.
(B) is shown.

That is, the electron gun 41 moves along the beam axis 42, for example, zirconium oxide / tungsten (ZrO 2).
/ W), an suppressor electrode 44 is arranged behind the emitter 43, an extractor electrode 45, an electron lens electrode 46, an anode electrode 47, and a blanking aperture 48 are sequentially arranged in front of the emitter 43. The magnetic pole unit 5 is provided between the magnetic pole 52 and the inner magnetic pole 53.
4 and the pole tip of the pole unit 54 is an insulator 5
6 is connected to an extractor electrode 45.
B is a magnetic field generated by the permanent magnet, and Φ
Is a curve controlled by the applied voltage Vl of the electron lens electrode 46 (the start and end of the curve are determined by the extractor voltage and the anode voltage, respectively). In the electron gun 41, since the electrons emitted from the emitter 43 are converged on the blanking aperture 48 and used, the convergence is controlled by the voltage Vl applied to the electron lens electrode 46. That is, the lens voltage Vl of the electron lens electrode 46 is a control for accurately converging to a position on the beam axis of the blanking aperture 48. Conversely, when the electron lens voltage V1 is applied, the lens voltage Vl on the electron beam axis 42 Only the convergence position can be controlled.

[0017]

However, in the electron gun of the technology disclosed above, the magnetic field is often generated by a coil. Moreover, at this time, the field electron emission phenomenon of the emitter portion in the vacuum chamber is 10-9 Torr.
It must be in a high vacuum state on the order of r.

However, for the lead wire constituting the coil, a wire material in which a polymer insulating material such as polyimide is coated on a wire material such as copper must be used. It is common to place the coil outside of the vacuum chamber for release.

Incidentally, in Japanese Patent Application Laid-Open No. 9-7538, a drawing is shown in which the coil is sealed by a gasket member although the description in the detailed description of the invention is omitted. Also, in the other disclosed examples, the coils are all placed in the atmosphere outside the vacuum chamber.

That is, as a result, the emitter portion is placed under a high vacuum in the vacuum chamber, and the coil is placed in the atmosphere or a low vacuum region outside the vacuum chamber. Of course,
It is necessary to devise such a method as to be installed away from the emitter or to integrate a part of the beam barrel with the magnetic pole. Although some effect can be expected by this, electrodes and magnetic poles such as emitter, suppressor electrode, extractor electrode, of course,
You have to keep a certain distance. Therefore, there is a problem that it is extremely difficult to apply a strong magnetic field.

To explain the second problem, there is a technique in which a magnetic field is applied by a permanent magnet depending on the type of the electron gun. However, these techniques integrate an extractor electrode and a magnetic pole and connect the tip of the magnetic pole to the electron beam axis. , A strong magnetic field of several hundred mT is applied to the tip of the emitter.

As described above, the method of applying a magnetic field to the extractor electrode has an effect of weakening the divergence effect near the emitter and the extractor electrode where electrons are strongly divergent and improving the convergence of the beam. Can reduce the spherical aberration coefficient defined by the image plane (image plane). However, in this case, the region of the applied magnetic field is narrow (the length on the axis is narrow).

Therefore, there is a problem that sufficient convergence cannot be obtained, and the position where the beam is converted from divergence to convergence near the extractor electrode on the beam axis cannot be changed.

A magnetic pole unit composed of only permanent magnets is good when used with normal accuracy.
For example, when using an electron gun mounted on an exposure device,
Particularly when high-precision adjustment is required, that is, the current angular density (the amount that determines the amount of current that can be used for exposure in an electron column for exposure) is adjusted and controlled with high accuracy, and the resist sensitivity during exposure is adjusted. When the magnetic pole unit is formed using only permanent magnets, it is difficult to finely adjust the current angular density, and as a result, optimization of injected electrons during exposure is difficult. There is a problem that it is difficult to perform with a single gun alone.

Further, the magnetic pole unit composed of only the electromagnetic coil has a drawback in that the number of turns of the electromagnetic coil becomes large, and the miniaturization of the magnetic pole unit is required.

The present invention has been made based on these circumstances, and provides an electron gun capable of finely adjusting the current angular density of an electron beam that can be used after passing through an aperture, and an exposure apparatus using the same. The purpose is to

[0027]

According to the first aspect of the present invention, a vacuum vessel, a cathode disposed in the vacuum vessel for generating an electron beam, and a magnetic field applied to the electron beam generated by the cathode are provided. A magnetic pole unit, an anode for accelerating an electron beam generated at the cathode in a beam axis direction to form an electron beam path, and an electron beam disposed between the anode and the cathode and accelerated by the anode. Wherein the magnetic pole unit has a structure in which a permanent magnet and an electromagnetic coil are arranged in a closed space. It is.

According to the second aspect of the present invention,
2. The electron gun according to claim 1, wherein the permanent magnet of the magnetic pole unit has been subjected to a surface treatment.

According to the third aspect of the present invention,
2. The electron gun according to claim 1, wherein the electromagnetic coil of the magnetic pole unit has been subjected to a surface treatment.

Further, according to the means of the present invention,
2. The electron gun according to claim 1, wherein the magnetic pole unit is formed by integrating at least one of the electrodes.

According to the invention of claim 5,
An exposure apparatus comprising the electron gun according to any one of claims 1 to 4.

According to the means of the invention of claim 6,
The electron beam is generated by the cathode arranged in the vacuum vessel,
In the electron beam generating method using an electron gun for applying an electric field to the electron beam generated by the cathode from a magnetic pole unit to adjust an electric field converged on an electron beam by an electron lens, the application of the magnetic field by the magnetic pole unit is applied to the magnetic pole unit. An electron beam generation method using an electron gun, which is based on a magnetic field generated from a permanent magnet and an electromagnetic coil provided.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the electron gun of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the electron gun. That is, as shown in FIG. 1, an electron gun 1 has an emitter 3 made of, for example, zirconium oxide / tungsten (ZrO / W) arranged along a beam axis 2,
A suppressor electrode 4, an extractor electrode 5,
An electron lens electrode 6, an anode electrode 7, and a blanking aperture 8 are sequentially arranged, and a closed space is defined by an outer magnetic pole 12, an inner magnetic pole 13, and non-magnetic substances 15a and 15b with a permanent magnet 10 and an electromagnetic coil 11 provided inside. The tip of the magnetic pole of the magnetic pole unit 14 is connected to the extractor electrode 5 via an insulator 16.

The structure of the magnetic pole unit 14 will be described in more detail. The nonmagnetic material 15 provided at both ends of the inner magnetic pole 13 is provided.
Reference numerals a and 15b are formed of a non-magnetic ceramic (or copper, aluminum, or Kovar glass) member, and are brazed to both ends of the magnetic pole. Furthermore, non-magnetic material 1
Seals 16a, 16b (gaskets) made of metal or the like are both provided on the joint surfaces of 5a, 15b and the outer magnetic pole 12, and hermetically seal a closed space formed between the outer magnetic pole 12 and the inner magnetic pole 13. ing. The electromagnetic coil 11 disposed in the closed space has a structure in which a current flows from the outside of the magnetic pole unit 14 via a feed-through (a connector subjected to vacuum sealing) not shown.

All of these electrodes and the magnetic unit 14 are disposed inside a lens barrel (not shown), and are maintained in a high vacuum by a vacuum pump such as an ion pump and are placed in a high vacuum environment.

A high voltage is applied to each of the emitter 3, the suppressor electrode 4, the extractor electrode 5, the electron lens electrode 6, and the anode electrode 7 by lead wires (not shown). The applied voltage is, for example, -500 V with respect to the emitter for the suppressor electrode 4, 1 to 5 KV for the extractor electrode 5, and 1 to 30 K for the anode electrode 7.
V, a voltage such as 1 to 30 KV is applied to the electron lens electrode 6, and the voltage (V) of the electron lens electrode 6 is
A voltage adjusted so as to connect a crossover (convergence point) is applied to the center of a blanking aperture 8 made of a metal plate or silicon having a small hole existing in front thereof.

The outer magnetic pole 12 and the inner magnetic pole 13 are made of a material having a high magnetic permeability such as pure iron. The permanent magnet 10 is made of samarium cobalt or the like, and is subjected to a surface treatment by plating. I have.

That is, usually, since the permanent magnet 10 such as samarium cobalt is a sintered metal, the permanent magnet 10 holds gas inside. Therefore, when used in a vacuum, the internal gas is released and a high vacuum cannot be obtained. Therefore, a member in which the surface of the permanent magnet 10 is plated with copper, nickel, or the like is used here to prevent the release of the internal gas.

The permanent magnet 10 is a samarium-cobalt magnet. However, the magnet is not limited to this, and may be a cerium-cobalt-based magnet, a neodymium iron-boron-based magnet, a ferrite-alnico-based magnet, a plastic magnet-based magnet, or an iron-chromium-cobalt-based magnet. , Etc. can be used regardless of the type.

The permanent magnet 10 is plated with a metal such as copper nickel. However, the present invention is not limited to this. For example, a treatment using a general metal or an alloy thereof, and a treatment using a multilayer film of a general metal or an alloy thereof. Not only plating, but also various coating treatments, or coating treatment with non-metals such as glass, and other gases such as sealing treatment with containers made of thin plates using stainless steel or other metals or non-metals, etc. Any treatment that does not release can be used as appropriate. Also,
If the sealing of the hermetic sealing portion is performed with high precision, a normal permanent magnet that emits gas can be used.

On the other hand, the electromagnetic coil 11 is formed by winding a conductor (diameter: 0.2 mm) coated with, for example, a polyimide a number of times (for example, 500 turns) around a magnet. In this case, the electromagnetic coil 11 is insulated and sealed with a suitable insulating member, or is subjected to a process of hardening a wire bundle of the wire. The conductor is not limited to a polyimide-coated conductor, but may be any wire made of aluminum or another conductive material coated with an insulating material that emits relatively little gas.

The gap not specified in FIG. 1 has a structure filled with a non-magnetic material such as copper.

FIGS. 2 (a), 2 (b) and 2 (c) are modifications of the above embodiment. In each case, the magnetic unit 1
Only the portion 4 is different, and the other portions are the same as those in the above-described embodiment. Therefore, the description of the same portion is omitted.

In the magnetic unit 14a shown in FIG. 2A, the permanent magnet 10a has the same arrangement as in the above embodiment, but the volume of the electromagnetic coil 11a is greatly increased along the inner electrode 13a. Therefore, in this case, three seals 16a, 16b and 16c are provided.

In the magnetic unit 14b shown in FIG. 2B, the permanent magnet 10b and the electromagnetic coil 11b
Are arranged in reverse. In this case, since the permanent magnet 10b also serves as a part of the sealing wall, only one seal 16b may be provided.

In the magnetic unit 14c shown in FIG. 2 (c), two electromagnetic coils 11c and 11d sandwich the permanent magnet 10c.
Are provided separately.

Next, a method of applying a magnetic field according to these configurations will be described.

FIG. 3 shows a generated potential distribution Φ and a magnetic field distribution B on the beam axis corresponding to the configuration.

That is, as means for applying a magnetic field,
A permanent magnet 10 and an electromagnetic coil 11 made of samarium cobalt plated with copper or nickel are used.

In FIGS. 3A and 3B, the horizontal axis is the position of the Z axis, and the vertical axis is the intensity of the magnetic field in arbitrary units. FIG.
Bp in (a) indicates the strength of the magnetic field of the permanent magnet 10, and is characterized in that a negative magnetic field (reversal magnetic field) exists because the permanent magnet 10 is used. On the other hand, ± Bc in FIG. 3A indicates the magnetic field of the electromagnetic coil 11. Electromagnetic coil 11
All the magnetic fields generated by these have characteristics in only one positive or negative direction. (The polarity of the magnetic field is determined by the direction of the current flowing through the coil.) Accordingly, the sum of the strengths of the two magnetic fields is such that the magnetic field ± Bc of the coil is added to the magnetic field Bp on the beam axis by the permanent magnet 10 as shown in FIG.

FIG. 3B shows the beam trajectory when the magnetic field shown in FIG. 3A is applied and the optimum voltage is applied to the lens electrode to converge the beam to the blanking aperture. FIG. 5 is a diagram (the horizontal axis indicates the position of the Z axis, and the vertical axis indicates the distance from the axis of the beam in arbitrary units).

Here, in the graph of FIG. 3B, the beam locus N indicates the emitter when the permanent magnet used in this electron gun is not magnetized (when the magnetic field is zero or the permanent magnet is removed). It is the trajectory of the emitted beam. In this case, the permanent magnet 1
The current of the electromagnetic coil 11 attached to 0 is also zero amperes or the coil magnetic field is zero. Next, the magnetized permanent magnet 1
When 0 is used (the magnetic field on the axis is Bp in FIG. 3A), the beam trajectory becomes M in FIG. In this case, the coil current of the beam locus M is zero amperes.

Here, the beam locus N in the absence of a magnetic field and the locus M in the presence of a magnetic field are compared. In each of the trajectories, if the coordinates on the Z-axis where the beam trajectories N and M are farthest from the Z-axis are Zc and Zm, the characteristic of the beam trajectory is M
This means that the beam goes from divergence to convergence at the position Zm from the emitter. Thereby, the beam locus M
Converges on the blanking aperture 8 (position Zba) at a convergence angle β (<α) smaller than the beam locus N. Therefore, the effect of the magnetic field of the magnet can be understood as an increase in the angular current density J = I / (πβ2) in addition to the change in the spherical aberration coefficient. As a result, particularly, since the angular current density J has a square relationship with the convergence angle, the reduction of the convergence angle is obtained as an effect of increasing the angular current density.

Next, when a current of 0.2 A is passed through the electromagnetic coil 11 to, for example, a winding of 500 turns, the total current becomes 100 AT (100 amp turns). By this excitation, a magnetic field Bc generated on the axis through the magnetic poles
Becomes a positive magnetic field in the entire region where the peak value is several mT (millitesla). If the direction of the exciting current is reversed, the generated magnetic field becomes -Bc (a negative magnetic field in the entire region). Further, this magnetic field is a magnetic field proportional to the amount of current, and can be controlled in all proportions on the axis in a completely proportional manner.

The magnetic field Bc is the same as the magnetic field B shown in FIG.
and Bc is approximately 1 / k (1/10 to 1/10) of the magnetic field Bp generated by the permanent magnet 10.
0). Further, this additional added magnetic field is
In order to change the beam locus M of the electron beam in (b),
The beam convergence angle β is β + · β − (+ Bc, β +
As a result, β + converges better and 0 <β + <β−
And the current angular density can be changed.

The peak value of the magnetic field Bc is, for example, 4
At mT, a calculation result is obtained in which the increase in the magnetic field increases the current angular density of +1 mA / Str. This is 1/5 to 1/5 of the current angular density J without adjustment by the coil.
It corresponds to an increase of 0. That is, the excitation by the coil (±
L ampere turn), the original current angular density J
Alternatively, the exposure current 1 can be adjusted by changing the value of J ± (1/5 to 1/50) J, and useful exposure conditions can be set that match the resist sensitivity, exposure time, and other exposure conditions. Was.

In the above-described embodiment, regarding the integration of the magnetic pole and the electrode, the extractor electrode 5 is used as the electrode.
However, the present invention is not limited to this. Although not shown, any other electrode and magnetic pole can be integrated. When the electrodes and the magnetic poles are integrated one-to-one, the electrodes and the magnetic poles are integrated via an insulator. However, when a plurality of electrodes and the magnetic poles are integrated, one of the electrodes and the magnetic poles are integrated. It is also possible to eliminate the insulator between them and apply a potential to the magnetic pole itself.

According to the above configuration, when a magnetic field generated by a permanent magnet is conventionally used, it is difficult to finely adjust the current angular density of an electron beam that can be used after passing through a blanking aperture. To do this, the size of the permanent magnet was changed, the size of the magnetic poles, and the gap between the magnetic poles were changed. This requires disassembly and reassembly of the electron gun, which is very time-consuming, and it is impossible to make adjustments while the electron gun is in operation.

In the above-described embodiment, by controlling the current from the outside of the electron gun (in the atmosphere), the predetermined current angular density can be adjusted with a precision of several tenths to several tenths. Settings can now be simplified.

Conventionally, the magnetic field on the beam axis is determined only by the performance of the permanent magnet, and thus, in general, the permanent magnet can generate a fixed magnetic field by magnetization. Due to variations and variations in magnetization conditions, the fixed magnetic field obtained by the permanent magnet is several percent.
Although the magnetic field on the beam axis also fluctuates due to the existence of the degree of variation, in the above-described embodiment, the magnetic field can be corrected by current control. Can be easily corrected for.

Also, the magnetic field on the beam axis as in the prior art is:
Since the fixed magnetic field of the permanent magnet was determined only by the performance of the permanent magnet, an error occurred due to the demagnetization that occurred over time (the fixed magnetic field gradually decreased) due to the temperature and other conditions. In such a case, it is possible to correct the magnetic field by controlling the current of the electromagnetic coil and maintain the initial value, so that the current angular density does not change with time due to demagnetization. This operation can be performed very simply by simply setting the electron gun in the atmosphere and operating the current value of the current source while the electron gun is in a normal use state.

Here, as shown in FIG. 6, a deceleration type lens voltage (Ve) is used as the lens electrode, and the extra voltage (Vex)
And a type lower than the anode voltage (Va)],
The same effect can be obtained with an acceleration type (a type in which Ve is higher than Vex or Va).

The above-described exposure technique using an electron beam emitted from an electron gun can be used for direct drawing, reduced projection, step-and-repeat, one-time batch projection, and the like. An example used in an electron beam writing apparatus will be described below.

FIG. 4 is a structural view showing the structure of an electron optical system on which the electron gun 70 is mounted. Inside the housing, from above, an electron gun 70, a first forming aperture 71, a forming deflector 72,
A second shaping aperture 73, a swing-back deflector 74, a blanking electrode 75, a magnification correction lens 76, a deflector and a focusing lens 77, and a processing chamber 78 are provided in this order.

A sample moving stage (not shown) is provided inside the processing chamber 78. This stage is configured such that the XY coordinates are accurately measured by a laser interferometer (not shown). The positioning is performed with an accuracy of several nm from. The positioning is performed by detecting a mark provided on the moving table or the sample.

[0066] Here, in order to take out the current long stable in the electron gun 70, it is necessary to reduce the influence of the gas generated from the wafer as a sample, the differential pumping, the electron gun chamber 5 × 10 ^- It is configured to maintain a high vacuum of ⁹ Torr or more.

The control system transfers data from a computer (not shown) to the drawing control system via an interface. The drawing control system selects an aperture figure corresponding to the pattern to be drawn on the wafer from the second forming aperture 73,
The required voltage from which this can be selected is input to the shaping deflector 72, and the beam is returned on-axis by the swing-back deflector 74. The selected drawing pattern is imaged on a sample (wafer) surface using a magnification correction lens 76 and a focusing lens 77.

At this time, an image is formed after the focus of the focusing lens is accurately adjusted based on the accurate distance measured in advance from the focusing lens 77 to the sample. Also,
By using a deflector configured in the focusing lens, the drawing pattern is imaged also in a portion other than the axis. The minimum dimension of a pattern that can be drawn is limited by aberrations and blurring of the electron optical system, and a dimension of about 0.1 μm or less is possible.

At this time, a single drawing pattern on the sample is exposed with, for example, L μm × L μm (3 μm × 3 μm).
The light is deflected by N · N ′ (for example, 10 × 12) by the deflector in the focusing lens, and exposure is performed. As a result, N
The exposure of the area of L μm × N ′ · L μm (30 μm × 36 μm) is completed. Next, the sample is moved on the moving stage, and on-axis exposure and deflection exposure are repeated to operate to complete exposure of the entire sample (for example, the entire surface of a 6 to 12 inch wafer).

As described above, a magnetic field immersion electron gun of a type in which a magnetic field is superimposed on a bipolar region including an emitter (electron emission source) and a beam is converged, and the electron gun is mounted thereon. Since the electron lens electrode and the magnetic pole unit are integrally formed, the electrons that can converge only at an emission angle of about several mrads are usually reduced from tens to hundreds of mrads.
Can be converged, and the number of electrons that can be used after passing through the aperture can be increased from the normal several nA order to several hundred nA or several μA, and can be precisely adjusted. .

Further, it is possible to improve the current angular density at which a beam that can pass through the aperture in the absence of a magnetic field is several mA / str from ten and several mA / str to several tens mA / str and to precisely adjust the current angular density. Now you can.

Further, a complicated structure of the electron gun chamber using the insulating sealing material is not required, and the cost can be reduced by reducing the number of parts.

Further, by using a permanent magnet for forming the magnetic field, the configuration is smaller than that of the electromagnetic magnet, and the magnetic field can be accommodated in the order of several tens mm to 100 mm in diameter.

Further, by increasing the accuracy of the shape and dimensions of the permanent magnet, the accuracy of assembling the electron gun is improved, and the alignment or adjustment mechanism of the electrodes can be simplified.

[0075]

According to the present invention, there is provided an electron gun capable of finely adjusting the current angular density of an electron beam which can be used after passing through an aperture, and an electron beam writing apparatus equipped with the electron gun. According to the exposure apparatus described above, a fine pattern can be processed with extremely high accuracy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an electron gun according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a modification of a main part of the electron gun according to the embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of an embodiment of the present invention, and a generated potential distribution Φ and a magnetic field distribution B on a beam axis corresponding to the configuration.

FIG. 4 is a configuration diagram showing a structure of an electron optical system of an electron beam writing apparatus equipped with the electron gun of the present invention.

FIG. 5 is a configuration diagram showing a configuration of a conventional field emission electron gun.

FIG. 6 is a diagram showing a configuration in which a conventional magnetic pole and an extractor electrode are integrated, and a potential distribution Φ and a magnetic field distribution B generated on a beam axis corresponding to the configuration.

[Explanation of symbols]

1, 31, 41 ... electron gun, 2, 32, 42 ... beam axis,
3, 33, 43 ... emitter, 4, 34, 44 ... suppressor electrode, 5, 35, 45 ... extractor electrode, 6, 3
6, 46 ... electron lens electrode, 7, 37, 47 ... anode electrode, 8 ... blanking aperture, 10, 10a,
10b ... permanent magnet, 11a, 11b, 11c, 11d ...
Electromagnetic coil, 12, 12a ... outer electrode, 13, 13a ...
Inner electrode, 14, 14a, 14b, 14c: magnetic pole unit, 15, 15a: non-magnetic material

Continued on the front page (72) Inventor Atsushi Ando 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 5C030 BB17 BC06 CC07 5F056 AA04 AA19 CB03 EA02

Claims (6)

[Claims] 1. A vacuum vessel, a cathode disposed in the vacuum vessel for generating an electron beam, a magnetic pole unit for applying a magnetic field to the electron beam generated by the cathode, and a beam axis for generating an electron beam by the cathode. An anode that accelerates in the direction to form an electron beam path, and an electron lens that is disposed between the anode and the cathode and generates an electric field that causes the electron beam accelerated by the anode to converge on the beam axis. Wherein the magnetic pole unit has a structure in which a permanent magnet and an electromagnetic coil are arranged in a closed space. 2. The electron gun according to claim 1, wherein the permanent magnet of the magnetic pole unit has been subjected to a surface treatment. 3. The electromagnetic coil of the magnetic pole unit,
2. The electron gun according to claim 1, wherein a surface treatment is performed. 4. The electron gun according to claim 1, wherein said magnetic pole unit is integrated with at least one of said electrodes. 5. An exposure apparatus comprising the electron gun according to claim 1. 6. An electron for generating an electron beam at a cathode disposed in a vacuum vessel, and applying a magnetic field from a magnetic pole unit to the electron beam generated at the cathode to adjust an electric field converged by an electron lens on a beam axis. In the electron beam generating method using a gun, the application of a magnetic field by the magnetic pole unit is based on a magnetic field generated from a permanent magnet and an electromagnetic coil provided in the magnetic pole unit.