JPH0391921A - Electron beam exposure device - Google Patents

Abstract

PURPOSE:To make it possible to correct the magnetic field of a focusing lens in accordance with the change of a beam current without having complicated adjustment by a method wherein a correction coil is composed of a plurality of coils having center axes which are in parallel with each other in different positions, and a magnetic field of the strength ratio determined in advance is generated from each coil. CONSTITUTION:A correction coil 20 is constituted by a plurality of coils 20a to 20c having center axes 22a to 22c in parallel with each other and located on different positions, and the coils 20a to 20c are constituted in such a manner that a magnetic field of strength ratio determined in advance will be generated therefrom. The strength ratio of generation of magnetic field of the coils 20a to 20c is determined in such a manner that the primary coupling of the deflection vector of the optical axis of an electron beam by the coils 20a to 20c will coincides with the optical axis of focusing lenses 8, 10 and 12. Consequently, as an action equal to the coincidence of the optical axis 11 of the focusing lenses the center axis of the correction coil 20 is obtained, a complicated adjustment of axis is unnecessitated, an electron beam exposing device, having a high throughput and a high degree of resolution, can be obtained.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an electron beam exposure apparatus, and an object of the present invention is to provide an electron beam exposure apparatus that has high throughput, does not require complicated axis adjustment, and has high resolution. In an electron beam exposure apparatus equipped with a converging lens and a correction coil for converging the beam onto a target according to a beam current value, the correction coil is composed of a plurality of coils whose central axes are parallel to each other and whose positions are different, Each coil is configured to generate a magnetic field with a predetermined intensity ratio.

[Industrial application field]

The present invention relates to an electron beam exposure apparatus.

In recent years, higher resolution and higher throughput have been required for electron beam exposure apparatuses. In order to obtain high throughput, a variable rectangular beam is used to shape and draw the electron beam.

This variable rectangular beam uses a combination of a plurality of slits to convert a fixed electron beam into an electron beam having a desired cross-sectional area. However, since the cross-sectional area of the electron beam is changed while the brightness of the electron beam is constant, the amount of electron beam current changes, and with the same convergence lens magnetic field strength, defocus occurs and resolution deteriorates. Therefore, there is a demand for an electron beam exposure apparatus that has both high resolution and high throughput.

[Conventional technology]

In conventional electron beam exposure apparatuses, in order to correct defocus, it was necessary to arrange a correction coil on the lens surface of the converging lens and finely adjust the intensity of the converging magnetic field in synchronization with changes in beam current. However, due to limitations in processing and assembly accuracy, it is unavoidable that a misalignment occurs between the optical axis of the converging lens and the center axis of the correction coil.As a result, when the correction coil performs convergence magnetic field correction, The position of the electron beam was misaligned.

In order to correct such a beam position shift on the image plane, conventional devices have a mechanism that feeds back a position correction proportional to the beam current value to the beam deflection system, or a mechanism that feeds back position correction proportional to the beam current value, or a mechanism that feeds back position correction proportional to the beam current value, or a mechanism that In order to prevent positional deviation itself from occurring, a mechanism for aligning the optical axis and the central axis has been provided.

[Problem to be solved by the invention]

However, among the above-mentioned conventional electron beam exposure apparatuses, the former apparatus requires calculation of values to be fed back from current values for all electron beams, and therefore has a problem of low throughput. In addition, in the latter device, it is necessary to increase the effect of the correction coil on the convergent lens magnetic field, and for this reason, the correction coil must be placed at the position where the convergent lens magnetic field has the maximum value, that is, near the lens surface. Since the objects to be adjusted are axes and axes, an alignment mechanism that is variable not only in the X and Y directions but also in the torsion position direction is required. The adjustment method was extremely complex.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electron beam exposure apparatus that has high throughput, does not require complicated axis adjustment, and has high resolution.

[Means to solve the problem]

The above problem is solved by a converging lens (8.
10.12) and a correction coil (20), the correction coil (20)
) is the central axis (2 2 a. 2 2 b. 2 2
c) is composed of a plurality of coils (2 0 a. 20 b, 20 c) parallel to each other and at different positions, and each coil (2 0 a. 2 0 b, 2 0 c)
) is constructed to generate a magnetic field with a predetermined intensity ratio.

[Effect]

A plurality of coils (2 0 a, 2 0 b, 2 0 c) that generate a magnetic field with a predetermined intensity ratio are
mutual central axes (2 2 a, 2 2 b, 2
2c) are arranged in parallel and at different positions to constitute a correction coil (20) for the convergent lens magnetic field. And each coil (2 0 a, 2 0 b,
Each coil (2 0 a.
By determining the intensity ratio of the magnetic field generation of 20 b, 20 c), the optical axis of the converging lens (11) and the correction coil (
It has the same effect as when the central axes of 20) coincide.

By using such a correction coil, mechanically complicated axis adjustment becomes unnecessary, and an electron beam exposure apparatus with high throughput and high resolution becomes possible.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an embodiment of an electron beam exposure apparatus of the present invention. In FIG. 1, an electron beam exposure apparatus 1 includes an electron gun 2 for emitting an electron beam, and a slit 4a for making the electron beam into a variable rectangular beam. 4
b. 6, and a converging lens 8 for converging the electron beam.
, 10.12, and a correction coil 20 disposed within the convergence lens 10 for correcting the convergence coil magnetic field,
The target 14 placed on the driver 16 is irradiated with an electron beam.

FIG. 2 is a sectional view of the converging lens 10 of the electron beam exposure apparatus (1) shown in FIG. It is a diagram. In Figures 2 and 3, the converging lens 1
Three coils 20a, 20b, and 20c are arranged inside the converging lens magnetic field correction coil 20.

Each coil 20a, 20b. 20c central axis 22a, 22
b. 22c are parallel to each other and parallel to the optical axis 11 of the converging lens 10 described above. Furthermore, each coil 20
a, 20b, 20c are arranged in order along the axial direction of the optical axis 1■, and the central axes 22a, 22
b. 22c is 360 on the same circumference centered on the optical axis 11.
/3=120 degrees apart.

FIG. 4 is a diagram showing the amount of deviation of the electron beam on the target surface 14 due to the convergent lens magnetic field correction coil 20. Each coil 20a, 20b. When an arbitrary current flows through 20c, a deflection force acts on the electron beam due to the horizontal magnetic field (perpendicular to the axis of the electron beam) of each coil. Here, the deflection forces of the coils 20a, 20b, and 20c are represented by vectors Va, Vb, and Vc, respectively.

Then, the sum Vx of the deflection vector Va by the coil 20a and the deflection vector vb by the coil 20b is increased by adjusting the amount of va or vb (in the illustrated example, the amount of the deflection vector vb is increased to ffiV' b shown by a broken line). ) can be determined to have the same magnitude and opposite direction as the deflection vector Vc of the coil 20c. That is, the coils 20a, 20b, 20c
By setting the magnetic field strength ratio to a predetermined value, the linear combination of the deflection vector of the optical axis of the electron beam by each coil aligns the optical axis 11 of the converging lens 10 with the central axis of the converging lens magnetic field correction coil 20. You can obtain the same effect as with Therefore, the coils 20a, 20b, 2
Once the magnetic field strength ratio of 0c is determined, the electron beam is targeted on the optical axis of the converging lens by determining the absolute value according to the change in beam current while maintaining the determined magnetic field strength ratio. can be converged to.

FIG. 5 shows a converging lens 1 showing another embodiment of the present invention.
FIG. 6 is a plan view showing the positional relationship of the coils that make up the correction coil 30 shown in FIG. 5. In FIGS. 5 and 6, the convergent lens magnetic field correction coil 30 disposed in the convergent lens 10 is composed of three coils 30a, 30b, and 30c having different coil diameters. Central axes 32a, 32b of each coil,
32c are parallel to each other and the optical axis 1 of the converging lens LO
It is parallel to 1. And each coil 30a, 30b. 3
In Qc, the coil diameters are large in this order, and at the same position in the axial direction of the optical axis 11 of the converging lens, the coil 30b is located inside the coil 30c, and the coil 30a is located inside the coil 30b.
It is arranged so that it is located inside. In this embodiment as well, each coil 3
0a30b. The magnetic field strength ratio of each coil is determined so that the linear combination of the deflection vectors 30c aligns the optical axis 11 of the converging lens 10 with the central axis of the converging lens magnetic field correction coil 30.

In the embodiment described above, the number of coils is three, but it may be four or more. That is, by configuring a convergent lens magnetic field correction coil with three or more coils, the linear combination of the deflection vectors of each coil is adjusted so that the optical axis of the convergent lens and the central axis of the convergent lens magnetic field correction coil coincide. becomes possible.

〔Effect of the invention〕

According to the present invention, as long as the optical axis of the converging lens and the center axis of the correction coil for the converging lens magnetic field are aligned by ↓ degrees, no further adjustment is necessary, and the above alignment is the first order of the deflection vector. This can be done by simply drawing a diagram to find the coupling, and there is no need for a complicated adjustment mechanism. Therefore, it is possible to correct the converging lens magnetic field according to changes in beam current without adversely affecting throughput. High resolution electron beam exposure equipment is possible.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view of the converging lens of the electron beam exposure apparatus shown in FIG. 1, and FIG. 3 is a sectional view of the correction coil shown in FIG. FIG. 4 is a plan view showing the positional relationship of the constituent coils; FIG. 4 is a diagram showing the amount of deviation of the electron beam due to the correction coil; FIG. 5 is a sectional view of a convergent lens showing another embodiment of the present invention; FIG. FIG. 6 is a plan view showing the positional relationship of the coils constituting the correction coil shown in FIG. 5. FIG. 1... Electron beam exposure device 2... Electron guns 4d, 4b, 6... Pickpocket
8.10.12...Converging lens 11...Optical axis 14...Target 16...Driver 20.30...Correction coil 20a. 20b, 20c, 30a, 30b, 30c...
- Coil 22a. 22b, 22c, 32a, 32b, 32c...
・Central axis

Claims (1)

[Claims] 1. The electron beam is directed to the target (1) according to the beam current value.
4) Converging lenses (8, 10, 12) for converging upward
) and a correction coil (20). , 20b, 20c)
An electron beam exposure apparatus characterized in that each coil (20a, 20b, 20c) generates a magnetic field with a predetermined intensity ratio. 2. The central axes of the plurality of coils (22a, 22b, 2
2c) is the optical axis (
2. The electron beam exposure apparatus according to claim 1, wherein the electron beam exposure apparatus is parallel to the optical axis (11) and is located in different directions from the optical axis (11) in a direction perpendicular to the optical axis (11). 3. The plurality of coils (20a, 20b, 20c) are N coils having the same number of windings, and the central axis (22a, 22b, 22c) of each coil is aligned with the converging lens (8).
, 10, 12) and located on the same circumference centered on the optical axis (11) at intervals of 360/N degrees. Beam exposure equipment. 4. The plurality of coils (30a, 30b, 30c) are arranged at different positions in the direction of the optical axis (11) of the convergent lens (8, 10, 12), or are coils with a large diameter. 2. The electron beam exposure apparatus according to claim 1, wherein coils (30a, 30b) having a small coil diameter are arranged inside the coil (30c) at the same position in the optical axis direction.