JPS62104122A - Electron-beam transfer apparatus - Google Patents

Abstract

PURPOSE:To simplify an apparatus and to implement a compact device and a low cost, by using permanent magnets as magnetic poles, sticking a high permeability material to the inner surface of each permanent magnet, and providing recessed shapes on the facing surfaces. CONSTITUTION:An N pole 11 and an S pole 12 face to each other. They are made of lanthanide rare earth magnet. A mask holder 18 is arranged on the side of the N pole and a mask 19 is held. A voltage of -80kV is applied to the N pole 11, and the mask is held at a negative potential. Permalloy 13, which provides a recessed surface 14 in the facing direction, is stuck to each of the N pole 11 and the S pole 12. By forming the recess surface 14, a protruded part 13a is formed around the Permalloy 13. A stage 21 is arranged over the S pole 12. A wafer 22 is mounted on the stage. At least one coil 15 and two Permally rings 16 are arranged between the N pole 11 and the S pole 12. Ultraviolet rays 23 are applied on a mirror 24. The rays reflected by the mirror 24 are projected on the mask 19. Electrons are discharged from the mask and converged, and the electron beam is projected on the wafer 22.

Description

[Detailed Description of the Invention] [Summary] A permanent magnet is used as the magnetic pole of an electron beam transfer device, and a high magnetic permeability material is pasted on the inner surface of the permanent magnet, so that the opposing surfaces are made concave.

[Industrial application field]

TECHNICAL FIELD This invention relates to electron beam transfer devices and, more particularly, to improvements in the magnetic poles of such devices.

[Conventional technology]

The 1:1 (equal magnification) transfer technique using an electron beam transfers a mask image onto a sample using an electron beam, and its principle is shown in FIG. A photocathode mask 32 and a sample (for example, a silicon wafer 37 whose surface is coated with an electronic resist 36) are oriented perpendicularly to the parallel magnetic field (in the vertical direction in the figure) created by a focusing coil (Helmholtz coil) 31. A voltage is applied such that the mask is negative and the sample is positive. The mask 32 creates a pattern to be transferred consisting of an ultraviolet absorber 34 on a quartz plate 33,
A palladium cathode 35 is made by applying a photoelectric substance (palladium) that emits electrons when irradiated with ultraviolet rays.

Ultraviolet light 3 emitted from the ultraviolet source 38 from above the quartz plate 33
When irradiated at step 9, the ultraviolet rays hit the photoelectric material in areas where there is no pattern (where there is no ultraviolet absorber 34), and electrons 40 are emitted from those areas as shown by the arrow.

The electron 40 emitted from one point on the mask 32 is moved to 'II!' due to the electric field there and the parallel magnetic field created by the focusing coil 31. It moves in a circular motion toward the sample, and at a certain point it converges again at one point, that is, it focuses.

FIG. 5 shows a part of the device structure, with a photoelectric mask 32 facing each other on the right side of the center of the figure, and a silicon wafer 37 on the left side of the center. The X-ray detector 40 on the left side of the wafer is used to perform alignment by detecting a line when electrons emitted from the alignment mark on the mask hit a heavy metal mark on the wafer. The deflection coil 41 deflects the electron beam emitted from the mask and is used to align the mask pattern with the pattern on the wafer.

[Problem that the invention seeks to solve]

The radius of the Helmholtz coil is a1 The distance between the coils is b
When the coils are arranged so that a=2b, a uniform magnetic field (uniform magnetic field) is created and electrons are focused. It is known that when a is 20 cm, a large current of 30,000 ampere turns is required in each coil to create an IK Gauss magnetic field.

Further, the Helmholtz coil needs to have the above-mentioned ampere-turn strength, so it needs to be a C1 superconducting coil and cooled to liquid helium temperature. This not only makes the device large and expensive, but also makes it difficult to incorporate a stage for mounting the sample. Furthermore, when placing a magnetic material near the Helmholtz coil as a shield or stage material, there is a problem in that it cannot be placed near the Helmholtz coil unless sufficient care is taken.

The present invention was created in view of these points, and aims to simplify the electron beam transfer device by using permanent magnets as magnetic poles, thereby realizing miniaturization and cost reduction of the device. .

[Means for solving problems]

FIG. 1 (al and fb) is a sectional view of an embodiment of the present invention.

In the electron beam transfer device of the present invention, the N pole (11)
Lanthanet rare earth magnets are used as the and S poles (12), and a high permeability material (permalloy) 13 is pasted on one or both surfaces of the opposing magnets, and the permalloy surface has a concave surface (
14), and at least one coil 15 is arranged for fine adjustment of the lines of magnetic force, and if necessary, a permalloy 16 is further arranged. Further, the north pole 11 and the south pole 12 are vacuum punctured using an O ring 17 as shown in the same figure (bl).

[Effect]

In the above magnetic pole structure, the N pole 11. ! : S pole 12
By setting the interval between 4 cm and applying ν to -80 to the N pole, an IK Gauss magnetic field is created, and the uniformity (uniformity) of the magnetic field lines is due to the concave surface of the permalloy 13 and the coil 15. lI is adjusted, and if necessary, permalloy is placed near the coil 15 to finely correct non-uniformity due to processing accuracy, calculation error, etc.

〔Example〕

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

Referring again to FIG. 1, the north pole 11 and the south pole 12 are arranged facing each other, and are made of lanthanet-based rare earth magnets. If necessary, the magnet is vacuum packed using an O-ring 17 as shown in FIG. 1(b).

In the structure shown in FIG. 1(a), a mask holder 18 is placed on the N pole side to hold the same mask 19 as in the conventional example,
A voltage of -80 to ν is applied to the N-pole 11 to maintain the mask at a negative potential.

A permalloy 13 is attached to the N pole 11 and the S pole 12, which provides a concave surface 14 toward the opposite side, as clearly shown on the S pole side. By creating the concave surface 14, a convex portion 13a is formed around the permalloy 13. The north pole 11 is supported by a ceramic support 20 .

A stage 21 is arranged above the S pole 12 as seen in the figure, and a wafer 22 is mounted on it. Between the north pole 11 and the south pole 12, at least one coil 15 and a permalloy ring 16 of 2 (II) are arranged.

In operation, the ultraviolet light 23 is applied to the mirror 24, the light reflected by the mirror 24 is irradiated to the mask 19, electrons are ejected from the mask as in the conventional example, and the electrons are focused and irradiated onto the wafer 22. .

In electron beam transfer, the above-mentioned focusing of the electron beam is important, and for this purpose, uniformity (uniformity) of the lines of magnetic force between the north pole and the south pole is required.

FIG. 2 is a schematic diagram for explaining the uniformity of magnetic lines of force formed by a permanent magnet, and the non-uniformity of magnetic force is exaggerated for the sake of explanation. Same figure (a), (bl, (0)
In this example, the north pole 11 and the south pole 12 are arranged at an interval of 100 mm, and each magnet has a diameter of 160 mm.

The same figure (al shows the magnetic field lines formed when only permanent magnets are used, and in this example, the uniformity is 1 cm from the center of the magnet.
10% at a distance and cannot be used in electron beam transfer equipment.

In the example shown in Figure 1), permalloy is pasted on the north pole 11 and the south pole 12, and although the uniformity in this case is improved to 2 to 3%, it is still not suitable for use in an electron beam transfer device. I can't.

In the example of the present invention shown in FIG. The convex portion toward 15 is repelled from the coil 15 by the magnetic field of the coil 15 shown by arrow I, and uniformity on the order of 10-5 is obtained, and the lines of magnetic force become straight.

However, depending on machining accuracy, calculation errors, etc., the magnetic lines of force may take a complicated shape as shown in FIG. 3 in addition to the state shown in FIG. 2. To fine tune it,
In addition to the coil 15, permalloy 16 is arranged. Incidentally, when there is only one coil, a large amount of power is required, but the arrangement shown in FIG. 3 solves this problem because it does not require a large amount of power per coil. By using a coil that repels or pulls magnetic lines of force and a ferromagnetic material (permalloy, iron) that attracts lines of magnetic force to straighten the outermost lines of magnetic force,
All other magnetic lines of force inside are straight, ensuring uniformity of the lines of magnetic force.

Lanthanet rare earth magnets become fatigued and their magnetic force deteriorates by 1 to 2% after approximately one year at maximum magnetization.

Therefore, it is preferable to obtain a semi-permanently fatigue-free permanent magnet by magnetizing it to 98%.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a magnetic pole for an electron beam transfer device that is simple, compact, inexpensive, does not require a power source, and can be easily incorporated into a stage.

[Brief explanation of drawings]

Figure 1 (al is a cross-sectional view of the embodiment of the present invention, Figure (b) is a cross-sectional view of a modified example of the magnetic pole of (al), Figures 2 [a), (b), and (C) are one of the lines of magnetic force. The figure (Ta) shows the case of only a permanent magnet, the figure (BL) shows the case where permalloy is pasted on the permanent magnet, and the figure (C) shows the case of the embodiment of the present invention. Figure 3 is a diagram showing fine adjustment of magnetic lines of force according to the present invention, and Figures 4 and 5 are cross-sectional views of conventional examples.In Figures 1 to 3, 11 is an N pole, 12 is an S pole, and 13 is a S pole. Permalloy, 13a is a protrusion of permalloy, 14 is a concave surface, 15 is a coil, 16 is permalloy, 17 is an O-ring, 18 is a mask holder, 19 is a mask, 20 is a ceramic support, 21 is a stage, 22 is a wafer, 23 is ultraviolet light, and 24 is a mirror. Shi J Invention Commercial Example Figure 1 This issue ε = Light Li? Tsukiyori 3 figure 2 evaporation”@t;7a 3 nose〃4m tnf&gotan11
at if co III'rI! 1ε convex s4 diagram

Claims (3)

[Claims] (1) N pole (
11) and S pole (12) are composed of Lanthanet-based rare earth magnets, and a high magnetic permeability material (13) is pasted on at least one surface of the opposing N pole (11) and S pole (12). (13
) has a concave surface (14), with N pole (11) and S pole (1
2) An electron beam transfer apparatus characterized in that a stage (21) on which a sample (22) is placed and at least one coil (15) are arranged between them. 2. Device according to claim 1, characterized in that in addition to the coil (15) at least one high permeability material (16) is arranged. (3) The device according to claim 1, wherein the north pole (11) and the south pole (12) are vacuum packed.