JPH0794131A - Electromagnetic lens and charged particle beam transfer device - Google Patents

Abstract

PURPOSE:To provide an electromagnetic lens having a fast response speed and a charged particle beam transfer device having high throughput. CONSTITUTION:A charged particle beam transmitted through a mask 6 having a pattern for transferring is radiated onto a photosensitive member 13 via a pair of electromagnetic lenses 8, 9 composed of coils 8A, 9A and magnetic substance cores 8B, 9B having two magnetic poles and arranged along an optical axis direction. In this charged particle beam transfer device, in at lease one electromagnetic lens 9, the core 9A is made of ferrite and a space between magnetic poles or an adjoining space between the magnetic poles is supported by an insulating member 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic lens and a charged particle beam transfer apparatus using the electromagnetic lens, and more particularly to an electromagnetic lens having a high response speed and a high throughput charged particle beam transfer apparatus.

[0002]

2. Description of the Related Art An electromagnetic lens is composed of a coil and a core having two magnetic poles. In this electromagnetic lens, the strength of the magnetic field on the axis of the electromagnetic lens is changed by changing the current flowing through the coil, and the focal length of the electromagnetic lens is adjusted. Since a magnetic material is used for the core and a large magnetic stress acts on the magnetic pole, soft iron or permalloy was used.

As a charged particle beam transfer apparatus, an electron beam reduction transfer apparatus, an ion beam reduction transfer apparatus, etc. are known, and both are subject to the present invention. The electron beam reduction transfer apparatus will be exemplified below. And explain. The electron beam reduction transfer device was configured as follows. That is, the pattern to be transferred onto the wafer is divided into a plurality of sub-fields of view on which a transfer is performed by irradiating the electron beam once on the mask. The irradiation of the sub-field of view with an electron beam has been performed by continuous movement of the mask stage on which the mask is mounted in one direction and deflection of the first deflector for selecting the sub-field of view, which is interlocked with this continuous movement. Then, the electron beam transmitted through the sub-field of view was applied to a predetermined position on the photosensitive member as follows. That is, the electron beam is reduced by the pair of electromagnetic lenses, the sample stage on which the photosensitive member is mounted is continuously moved in the direction opposite to the mask stage, and the deflection of the second deflector is interlocked with the continuous movement of the mask stage. Therefore, the electron beam was applied to a predetermined position on the photosensitive member. For this reason, since the optical path of the electron beam from the sub-field of view to the photosensitive member differs for each sub-field of view, it is necessary to adjust the focal length of the pair of electromagnetic lenses for each sub-field of view. Then, after waiting for the adjustment of the focal lengths of the pair of electromagnetic lenses, the electron beam is irradiated to a predetermined sub-field of view.

The pair of electromagnetic lenses were arranged in the direction along the optical axis. The focal lengths of the pair of electromagnetic lenses are adjusted by changing the currents flowing through the coils of the pair of electromagnetic lenses.

[0005]

However, the soft iron and permalloy used in the core of the electromagnetic lens had a frequency characteristic of the material itself of about 20 Hz. For this reason, the conventional electromagnetic lens has a problem that it takes 50 mSEC or more to stabilize the magnetic field generated in the magnetic pole after changing the current flowing in the coil.

Further, in the charged particle beam transfer apparatus, since the focal length of the electromagnetic lens is adjusted for each sub-field of view, the current passed through the coil is changed according to each sub-field of view. For this reason, it is necessary to wait for the magnetic field to stabilize each time, and in the conventional electromagnetic lens, there is a problem that it takes time to stabilize the magnetic field and throughput decreases. Therefore, an object of the present invention is to provide an electromagnetic lens having a fast response speed and a charged particle beam transfer apparatus having a high throughput.

[0007]

In order to solve the above-mentioned problems, a description will be given in association with FIG. 1 showing an embodiment, in which the electromagnetic lens of the present invention is a magnet having a coil (9A) and two magnetic poles. In an electromagnetic lens (9) including a body core (9B), the core (9B) of the electromagnetic lens (9) is made of ferrite, and an insulating member (10) is provided between two magnetic poles or in the vicinity of the two magnetic poles. Is supported by.

In the charged particle beam transfer apparatus of the present invention, the charged particle beam transmitted through the mask (6) having a transfer pattern is used as a coil (8A, 9A) and a magnetic core (8B) having two magnetic poles. , 9B), and a charged particle beam transfer apparatus for irradiating the photosensitive member (13) with light through a pair of electromagnetic lenses (8, 9) arranged along the optical axis direction.
At least one electromagnetic lens (9) has a core (9B) made of ferrite, and supports between the magnetic poles or in the vicinity of the magnetic poles with an insulating member (10).

[0009]

The electromagnetic lens (9) of the present invention uses ferrite for the core (9B). Since the frequency characteristic of ferrite is about 200 KHz, it takes only about 5 μSEC to stabilize the magnetic field even if the current flowing through the coil (9A) changes. Therefore, the response speed is faster than that of the conventional electromagnetic lens.

By supporting the magnetic poles of the core or the vicinity of the magnetic poles with the insulating member (10), the ferrite is not damaged by the magnetic stress. The charged particle beam transfer apparatus of the present invention uses the above electromagnetic lens as at least one electromagnetic lens (9) of the pair of electromagnetic lenses (8, 9). Therefore, when the electric currents flowing through the pair of electromagnetic lenses (8, 9) are adjusted for each sub-field of view, the magnetic field stabilizes quickly, so that high throughput can be realized.

Further, since there is only the insulating member (10) between the electron beam passing through the electromagnetic lens (9) and the coil (9A), the influence of the ozon current generated when a conductive member is placed. Nor. Therefore, the response speed of the magnetic field does not decrease when the current of the electromagnetic lens (9) is changed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic diagram of an electron beam reduction transfer apparatus of the present invention. In FIG. 1, the electron beam emitted from the electron gun 1 is
While focusing, the first condenser lens 2 passes through the aperture of the aperture 3 to form a crossover. The second condenser lens 4 collimates the electron beam forming the crossover into a parallel light flux. The first deflector 5 deflects the parallel light flux two-dimensionally. This two-dimensional deflection and mask 6
By the continuous movement of the mask stage 7 on which is mounted in one predetermined direction, the electron beam that has become a parallel light flux is sequentially irradiated to a predetermined region on the mask 6. The mask 6 is formed with a transfer pattern, and is divided into a plurality of areas (hereinafter referred to as sub-fields) to be transferred by one irradiation. The mask stage 7 is driven by a drive motor (not shown).

The first electromagnetic lens 8 and the second electromagnetic lens 9 reduce-project the electron beam transmitted through the sub-field of view onto the wafer 13. The first electromagnetic lens 8 and the second electromagnetic lens 9 are coils 8
A, 9A and a ferrite core 8B having two magnetic poles,
9B and. Further, the second electromagnetic lens 9
Is supported between two magnetic poles by an alumina ceramic 10 which is an insulating member.

The second deflector 11 uses a magnetic pole on the mask 6 side of the core 8B of the first electromagnetic lens 8 as a core. According to the reduction ratio of the first electromagnetic lens 8 and the second electromagnetic lens 9, the second
The deflector 11 deflects the electron beam transmitted through the sub-field of view. The deflection of the second deflector 11 and the wafer stage 12 described later.
With the continuous movement of, the sub-field pattern is transferred to a predetermined position on the wafer 13 mounted on the wafer stage 12.

The pattern of the sub-field of view is reversed by the first electromagnetic lens 8 and the second electromagnetic lens 9. Therefore, the wafer stage 12 continuously moves in a direction opposite to the continuous movement direction of the mask stage 7. The wafer stage 12 is driven by a drive motor (not shown). As described above, a desired pattern can be formed on the wafer 13 by sequentially irradiating the sub-field pattern with the electron beam.

Note that the mask 6 is not irradiated with the electron beam until the electron beam irradiation conditions for the sub-field of view are set.
The blanking deflector 14 deflects the electron beam toward the beam catcher 15. The CPU 16 performs various calculations for forming a desired pattern on the wafer 13 and controls the deflector drive circuit 17 and the focus adjustment circuit 18.

The deflector drive circuit 17 controls the first deflector 5, the second deflector 11, and the blanking deflector 14 in accordance with a command from the CPU 16. The focus adjustment circuit 18 is a CPU
According to the command of 16, the current supplied to the first electromagnetic lens 8 and the second electromagnetic lens 9 is controlled to adjust the focal length. The operation of the electron beam reduction transfer apparatus configured as described above will be described below.

As described above, the electron beam emitted from the electron gun 1 receives the first condenser lens 2, the aperture 3 and the second condenser lens 2.
It passes through the condenser lens 4. The CPU 16 controls the deflection amount of the first deflector 5 via the deflector drive circuit 17 so that the electron beam irradiates a predetermined sub-field of view. The optical path from each sub-field of view to the wafer 13 is different for each sub-field of view in accordance with this deflection amount. Therefore, the CPU 16 causes the first electromagnetic lens 8 and the second electromagnetic lens 9 via the focus adjustment circuit 18.
The focal length is adjusted by controlling the current applied to and.

In this embodiment, the cores 8B and 9B of the first electromagnetic lens 8 and the second electromagnetic lens 9 are made of ferrite. Therefore, when the currents flowing through the coils 8A and 9A of the first electromagnetic lens 8 and the second electromagnetic lens 9 are changed to adjust the focal length, the magnetic field generated in the magnetic poles of the cores 8B and 9B is stabilized at 5 μSEC. It only takes a degree. As a result, the time during which the blanking deflector 14 deflects the electron beam is reduced, so that the mask stage 7 and the wafer stage 12 are
The continuous moving speed of can be increased. Therefore, high throughput can be realized.

When the magnetic pole spacing is short, particularly strong magnetic stress acts on the magnetic poles. Therefore, in this embodiment, since the alumina ceramics 10 support between the magnetic poles of the core 9B of the second electromagnetic lens 9, the ferrite is not damaged.
In the present embodiment, the alumina ceramic 10 has a cylindrical shape. However, a plate shape may be used as long as it can sufficiently support the magnetic poles.

Further, since there is only the alumina ceramic 10 which is an insulating member between the electron beam passing through the second electromagnetic lens 9 and the coil 9A of the second electromagnetic lens 9, this occurs when a conductive member is placed. There is no influence of the louze current. Therefore, the response speed of the magnetic field does not decrease when the current flowing through the coil 9A of the second electromagnetic lens 9 is changed. In this embodiment, only the magnetic poles of the core 9B of the second electromagnetic lens 9 are supported by the alumina ceramic 10, but the magnetic poles of the core 8B of the first electromagnetic lens 8 may be supported by the alumina ceramic 10. Of course.

FIG. 2 shows a modification of the present invention in which an alumina ceramic 10 which is a support member for the second electromagnetic lens 9 is arranged at a position near the magnetic poles. In the present invention, the support member prevents the ferrite from being damaged. Therefore, as shown in FIG. 2, even if the alumina ceramic 10 as the supporting member is arranged in the vicinity of the magnetic poles, the same effect as that of the above-described embodiment can be obtained. The configuration other than the second electromagnetic lens 9 is the same as the configuration of the apparatus in FIG.

FIG. 3 shows a second modification of the present invention in which coils 8A and 9A of the first electromagnetic lens 8 and the second electromagnetic lens 9 are provided with focus adjusting coils 19 and 20 for sub-fields of view, respectively. In this case, the focus adjustment circuit 18 controls the current flowing through the focus adjustment coils 19 and 20 for the sub-field of view according to each sub-field of view. The configuration other than the above is the same as the configuration of the apparatus in FIG.

Since the adjustment amount of the focal length for each sub-field of view is not large, in the second modification, the currents flowing through the coils 8A and 9A of the first electromagnetic lens 8 and the second electromagnetic lens 9 are kept constant and the sub-field of view is used. Only the current flowing through the focus adjusting coils 19 and 20 is adjusted for each sub-field of view. Therefore, the focus adjustment circuit 1
Reference numeral 8 can control the sub-field focus adjusting coils 19 and 20 with a small current.

FIG. 4 is a diagram showing a cooling device for the second electromagnetic lens 9. The cooling device 21 is for sending constant temperature water to the second electromagnetic lens 9. The O-ring 22 is a seal for preventing constant temperature water from leaking into the electron optical system. Since the second electromagnetic lens 9 has a short dimension in the optical axis direction, it cannot sufficiently radiate the heat generated by the current flowing through the coil 9A.
Since the second electromagnetic lens 9 is close to the wafer 13,
When the heat generated from the electromagnetic lens 9 is transmitted to the wafer 13, the dimensions of the wafer 13 may be deformed and the transfer accuracy may be deteriorated. Therefore, it is necessary to cool the second electromagnetic lens 9.

The constant temperature water sent from the cooling device 21 is
It enters from below the second electromagnetic lens 9 close to the wafer 13. Then, the coil 9A and the cylindrical alumina ceramic 10
After passing through the clearance between the second electromagnetic lens 9 and the cooling device 21, the second electromagnetic lens 9 returns to the cooling device 21. In this embodiment, the coil 9A is covered with a polyimide (not shown) and constant temperature water is flown between the coil 9A and the core 9B. Therefore, the constant temperature water is not applied to the coil itself, and the heat generated from the coil can be efficiently removed.

Further, in order to prevent the constant temperature water from leaking into the electron optical system, the alumina ceramic 10 has a cylindrical shape and O-ring grooves are provided on the upper surface and the lower surface, and the O-ring 22 is provided between the magnetic pole and the alumina ceramic 10. It is sealed with. Of course, the first electromagnetic lens 8 may be cooled by the above method. In the present embodiment, the core of the second deflector 11 is shared with the ferrite core 8B of the first electromagnetic lens 8. Therefore, the response of the second deflector 11 is also improved. Also, by making the core of the first deflector 5 made of ferrite, the responsiveness is improved and higher throughput can be realized.

[0028]

As described above, since the electromagnetic lens of the present invention uses ferrite for the core, it has a high response speed. Since the magnetic poles or the vicinity of the magnetic poles are supported by the insulating member, it is possible to prevent the ferrite from being damaged by magnetic stress without lowering the response speed.

The charged particle beam transfer apparatus of the present invention uses the above-mentioned electromagnetic lens as at least one electromagnetic lens of the pair of electromagnetic lenses. Therefore, the magnetic field stabilizes quickly when the currents flowing through the pair of electromagnetic lenses are adjusted for each sub-field of view, so that a high-throughput electron beam transfer apparatus can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an electron beam reduction transfer apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing a second electromagnetic lens 9 that is a modified example of the invention.

FIG. 3 is a diagram showing a first electromagnetic lens 8 and a second electromagnetic lens 9 that are a second modified example of the present invention.

FIG. 4 is a diagram showing a second electromagnetic lens 9 and a cooling device 21 of the present invention.

[Explanation of symbols]

 6 Mask 8 1st electromagnetic lens, 8A coil, 8B core 9 2nd electromagnetic lens, 9A coil, 9B core 10 Alumina ceramic 13 wafer of support member

Claims (2)

[Claims] 1. An electromagnetic lens comprising a coil and a magnetic core having two magnetic poles, wherein the electromagnetic lens has a core made of ferrite.
An electromagnetic lens, characterized in that an insulating member supports one magnetic pole or the vicinity of the two magnetic poles. 2. A pair of electromagnetic lenses comprising a coil and a core of a magnetic material having two magnetic poles for arranging a charged particle beam transmitted through a mask having a pattern for transfer and arranged along the optical axis direction. In a charged particle beam transfer apparatus for irradiating a photosensitive member via a magnetic recording medium, the core of at least one electromagnetic lens is made of ferrite, and the magnetic poles or the vicinity of the magnetic poles are supported by an insulating member. Charged particle beam transfer device.