JPH10340698A - Electron beam lithography apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam lithography apparatus which is inexpensive and can perform a high-grade external magnetic field shielding. SOLUTION: Generally, a magnetic circuit part between magnetic field type electron lenses among magnetic circuit parts 7 of a focusing electron lens system is a part where transmitted magnetic fluxes are fewer. Hence, this portion is provided with a magnetic flux shunting nonmagnetic part 8, for example, composed of a cavity which opens to a magnetizing coil of a lower electron lens, and accordingly, a magnetic circuit part existing between electron lenses is formed as a shunting magnetic circuit part regarding the lower electron lens. With this configuration, regarding the lower electron lens, magnetic fluxes generated at the magnetizing coil are shunted so as to pass through a magnetic circuit part surrounding the magnetic flux shunting nonmagnetic part 8, that is a shunt magnetic circuit part, and therefore the magnetic flux density in the shunt magnetic circuit part increases compared with a case without the magnetic flux shunting nonmagnetic part 8, i.e., the magnetic permeability at the part is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam lithography apparatus, and more particularly to an electron beam lithography apparatus suitable for performing fine processing in the semiconductor manufacturing field.

[0002]

2. Description of the Related Art In recent years, an electron beam lithography apparatus has been attracting attention as an exposure apparatus for the most advanced fine devices due to its high resolution.
However, since the throughput is low and the cost is high, the cost performance is conventionally inferior to that of light exposure or the like. In particular, since electrons are elementary particles with a large specific charge and light weight, they are sensitive to the external environment, especially to magnetic field fluctuations, and require the use of expensive high-permeability materials such as permalloy, and in some cases, a shield room. I do. The installation of the shield room not only limits the price and the installation conditions, but also adversely affects the maintainability of the apparatus and the layout change.

In order to effectively shield an external magnetic field, a magnetic material having as high a magnetic permeability as possible is used. However, alloys such as permalloy, which is a high magnetic permeability material, have a magnetic permeability of ~
Although effective as about 10,000, it is very expensive. On the other hand, pure iron or the like is inexpensive in price, but its shielding effect is several tens of times lower than that of the preceding alloy because the initial permeability is as small as ~ 300 especially for ordinary geomagnetic levels. In order to obtain a sufficient shielding effect with pure iron, considerable weight is required, which also hinders price and maintainability.

For this reason, an electron optical system which is hardly affected by an external magnetic field fluctuation is important for reducing the total cost of the apparatus.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron beam lithography apparatus which is inexpensive and capable of high-level shielding of an external magnetic field.

[0006]

According to one aspect, an electron beam lithography apparatus according to the present invention comprises an electron beam generating means and a plurality of magnetic field type electron lenses for focusing the generated electron beam. A focusing lens system, means for deflecting the focused electron beam to a desired position on a sample, and a means for deflecting the electron beam so as to form a predetermined pattern on the sample. Means for controlling deflection, wherein a magnetic circuit between the electronic lenses is formed as a detour magnetic circuit by providing a non-magnetic part in the magnetic circuit, and thereby a magnetic circuit from the excitation coil constituting the electronic lens is provided. It is characterized in that a magnetic flux is made to bypass the bypass magnetic circuit section.

According to another aspect, an electron beam lithography apparatus according to the present invention includes: a means for generating an electron beam; a focusing lens system including a plurality of magnetic field type electron lenses for focusing the generated electron beam; Means for deflecting the focused electron beam so as to be positioned at a desired position on the sample; and means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. A magnetically closed circuit comprising a magnetic shield exciting coil and a magnetic material surrounding the exciting coil is provided inside or inside the magnetic circuit section between the electron lenses.

According to still another aspect, an electron beam lithography apparatus according to the present invention comprises: a means for generating an electron beam; a focusing lens system including a plurality of magnetic field type electron lenses for focusing the generated electron beam; Means for deflecting the focused electron beam to a desired position on the sample, and means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. A magnetic closed circuit comprising a magnetic shield excitation coil and a magnetic material surrounding the excitation coil for the magnetic shield is provided outside the magnetic circuit portion of the electron lens system.

According to another aspect, an electron beam lithography apparatus according to the present invention includes: a means for generating an electron beam; a focusing lens system including a plurality of magnetic field type electron lenses for focusing the generated electron beam; Means for deflecting the focused electron beam to a desired position on the sample, and means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. An exciting coil for a magnetic shield is wound around an outer periphery of a magnetic circuit portion of the electron lens system.

According to still another aspect, an electron beam lithography apparatus according to the present invention includes: a unit for generating an electron beam;
A focusing lens system comprising a plurality of magnetic field type electron lenses for focusing the generated electron beam, and a focused electron beam.
Means for deflecting the electron beam to a desired position on the sample, and means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. Wherein the magnetic circuit portion is made of a magnetic material having a higher magnetic permeability than the magnetic circuit portion around the electron lens exciting coil.

[0011]

FIG. 1 shows an embodiment of an electron beam drawing apparatus to which the present invention is applied. An electron beam 4 emitted from an electron source 1 is focused on a sample 6 by a focusing electron lens system 2 including a plurality of magnetic field type electron lenses. Beam deflector 3
Is for deflecting the focused electron beam, and the deflection is controlled by a controller (not shown) so as to form a predetermined pattern on the sample 6.

FIG. 2 shows a conventional focusing electron lens system used in an electron beam drawing apparatus. This focusing electron lens system is an example including two magnetic field type electron lenses. . The magnetic flux generated by the excitation coil 6 of the electron lens passes through the magnetic circuit section 7 therearound, thereby generating a strong converging magnetic field in the gap on the beam path side. The external magnetic field mainly enters from a magnetic circuit portion in a region having a small magnetic permeability, that is, a region having an initial magnetic permeability and a saturation, and adversely affects the trajectory of the electron beam 4.

FIG. 3 shows an embodiment of the focusing electron lens system of the electron beam writing apparatus according to the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals (the same applies to FIG. 4 and subsequent drawings). Generally, the magnetic circuit unit 7
Of these, the magnetic circuit portion between the magnetic field type electron lenses is a portion where the transmitted magnetic flux is small. For this reason, in this portion, for example, a magnetic flux detour gap 8 that is opened to the excitation coil of the lower electronic lens is provided, so that the magnetic circuit between the electronic lenses in the lower electronic lens serves as a detour magnetic circuit. It is formed.

According to this, with respect to the lower electron lens, the magnetic flux generated by the excitation coil passes around the magnetic circuit around the magnetic flux detouring non-magnetic portion 8, which is a gap, that is, the detour magnetic circuit. Therefore, the magnetic flux density is increased in the detour magnetic circuit part compared with the case where the non-magnetic part for magnetic flux detour 8 is not provided, and the magnetic permeability in that part is increased. For example, when the magnetic circuit portion is made of pure iron, the magnetic circuit portion between the electronic lenses has only an initial magnetic permeability region of about 300 with respect to a normal terrestrial magnetism when there is no magnetic flux detouring nonmagnetic portion 8. Thus, the magnetic permeability of that portion can be increased to the maximum magnetic permeability of about 8000 by providing the non-magnetic portion 8 for magnetic flux detour. As a result, the external magnetic field shield effect is improved, and the effect of the external magnetic field fluctuation (for example, the external magnetic field fluctuation of the terrestrial magnetic level) on the electron beam 4 can be eliminated.

The magnetic flux detouring non-magnetic portion 8 may be made of another non-magnetic material, such as copper, aluminum, or cement, other than the gap.
May be formed.

Electron lenses are relatively sensitive to temperature changes, which change lens characteristics, specifically the focal length. For this reason, in FIG. 3, in order to effectively utilize the magnetic flux detouring nonmagnetic portion 8 formed of the gap, a pipe 11 is passed through this portion, and a liquid or gas controlled at a constant temperature by the constant temperature control device 12 is caused to flow through the pipe 11 so that the electron The lens is kept at a constant temperature.

FIG. 4 shows another embodiment according to the present invention. This embodiment is an example in which a magnetic closed circuit composed of an exciting coil 9 for a magnetic shield and a magnetic body 10 for a magnetic shield surrounding the exciting coil 9 for the magnetic shield is provided inside the magnetic circuit section between the electronic lenses. In this example, the size (thickness) and the exciting current of the exciting coil 9 are adjusted and set so that the magnetic body 10 has the maximum magnetic permeability. According to this embodiment as well, the magnetic shield effect can be improved through the magnetic circuit section between the electron lenses.

The magnetic closed circuit may be embedded not only inside the magnetic circuit section between the electronic lenses but also inside it. Further, if a gap is provided between the magnetic circuit portion and the magnetic closed circuit body, the magnetic shield effect can be further enhanced.

FIG. 5 shows still another embodiment according to the present invention. This embodiment is an example in which a magnetic closed circuit comprising an exciting coil 13 for a magnetic shield and a magnetic body 14 surrounding the exciting coil 13 is provided outside the magnetic circuit of the focusing electron lens system.
In this example, the size (thickness) and the exciting current of the exciting coil 13 are adjusted so that the magnetic material has the maximum magnetic permeability.
Is set. According to this embodiment as well, the magnetic shield effect can be improved through the magnetic circuit section between the electron lenses.

If a gap is provided between the magnetic circuit section of the focusing electron lens system and the magnetic closed circuit body, the magnetic shield effect can be further enhanced. Further, a higher magnetic shielding effect can be obtained even if an exciting coil for magnetic shielding is wound around the outer periphery of the magnetic circuit portion of the focusing lens system.

Even if the entire magnetic circuit portion of the focusing electron lens system is made of pure iron, and only the magnetic circuit portion between the electron lenses is made of a material having a higher magnetic permeability than the other portions, for example, permalloy, almost the same. A magnetic shield effect is obtained.

According to the embodiment of the present invention, an inexpensive and high-level external magnetic field shield is possible. In other words, even an inexpensive magnetic material can be expected to have the same effect as a high-permeability alloy, and the total cost can be reduced by eliminating the need for a shield room.

[0023]

According to the present invention, there is provided an electron beam lithography apparatus which is inexpensive and capable of shielding a high external magnetic field.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an electron beam drawing apparatus to which the present invention is applied.

FIG. 2 is a longitudinal sectional view of a conventional focusing lens system used in an electron beam drawing apparatus.

FIG. 3 is a longitudinal sectional view of a focusing electron lens system of an electron beam lithography apparatus showing one embodiment according to the present invention.

FIG. 4 is a longitudinal sectional view of a focusing electron lens system of an electron beam lithography apparatus showing another embodiment according to the present invention.

FIG. 5 is a longitudinal sectional view of a focusing electron lens system of an electron beam lithography apparatus showing still another embodiment according to the present invention.

[Explanation of symbols]

1: Electron source, 2: Focusing electron lens system, 3: Beam deflector, 4: Electron beam, 5: Sample, 6: Exciting coil of magnetic field type electron lens of focusing electron lens system, 7: Magnetic field of focusing electron lens system Magnetic circuit part of shaped electron lens, 8: Non-magnetic part for magnetic flux detour, 9, 13: Excitation coil for magnetic shield, 10,
14: magnetic material for magnetic shield, 11: pipe, 12: constant temperature controller.

Claims (10)

[Claims] 1. A means for generating an electron beam, a converging lens system comprising a plurality of magnetic field type electron lenses for converging the generated electron beam, and the converged electron beam being moved to a desired position on a sample. Means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample; and An electron beam lithography device, wherein a non-magnetic portion is provided in the portion to form a bypass magnetic circuit portion, whereby magnetic flux from an exciting coil constituting the electron lens is caused to bypass the bypass magnetic circuit portion. apparatus. 2. The electron beam lithography apparatus according to claim 1, wherein said bypass magnetic circuit section has a dimension that allows a substantially maximum magnetic permeability to be obtained. 3. An electron beam lithography apparatus according to claim 1, wherein a pipe is passed through said non-magnetic portion, and a liquid or gas at a constant temperature is passed through said pipe. 4. A means for generating an electron beam, a focusing lens system comprising a plurality of magnetic field type electron lenses for focusing the generated electron beam, and positioning the focused electron beam at a desired position on a sample. Means for deflecting the electron beam and means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. An electron beam lithography system comprising a magnetic excitation circuit for a shield and a magnetic closed circuit comprising a magnetic material surrounding the excitation coil. 5. An electron beam lithography apparatus according to claim 4, wherein a gap is provided between a magnetic circuit portion between said electron lenses and said magnetic closed circuit structure. 6. A means for generating an electron beam, a focusing lens system comprising a plurality of magnetic field type electron lenses for focusing the generated electron beam, and positioning the focused electron beam at a desired position on a sample. Means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample, and a magnetic system provided outside the magnetic circuit of the electron lens system. An electron beam lithography apparatus provided with a magnetic excitation circuit for magnetic field and a magnetic closed circuit structure composed of a magnetic material surrounding the excitation coil. 7. The electron beam lithography apparatus according to claim 6, wherein a gap is provided between the magnetic circuit section of the electron lens system and the magnetic closed circuit structure. 8. The magnetic shield magnetic material according to claim 4, wherein the magnetic material for the magnetic shield is magnetized by the excitation coil for the magnetic shield so as to have substantially the maximum magnetic permeability. An electron beam lithography apparatus according to claim 1. 9. A means for generating an electron beam, a focusing lens system comprising a plurality of magnetic field type electron lenses for focusing the generated electron beam, and positioning the focused electron beam at a desired position on a sample. And a means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. A magnetic system is provided around the magnetic circuit of the electron lens system. An electron beam lithography apparatus, wherein an excitation coil for the field is wound. 10. A means for generating an electron beam, a converging lens system comprising a plurality of magnetic field type electron lenses for converging the generated electron beam, and the converged electron beam at a desired position on a sample. Means for deflecting the electron beam, and means for controlling the deflection of the electron beam so as to form a predetermined pattern on the sample. An electron beam lithography apparatus comprising a magnetic material having a higher magnetic permeability than a magnetic circuit portion around an exciting coil.