JPS61263020A - Electron gun - Google Patents

Abstract

PURPOSE:To obtain an electron gun having a multi-emitter which is highly precise, highly durable and excellent in thermoelectron emission efficiency by forming grooves having side faces nearly vertical to the surface of an emitter chip and so s to form plural pillar shaped emitters. CONSTITUTION:Firstly, a LaBs single crystal chip 1' is machined to obtain a square pillar of approx. 700mum square and its head is machined flat by polishing. Next, as shown by dotted lines, a set of two grooves 3 in each of longitudinal and lateral directions, namely four grooves 3 in total arearranged whereby nine pillar-shaped emitters 2 are formed. This results in obtaining an electron gun having a multi-emitter which is highly precise, highly durable and excellent in thermionic emission efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electron gun in an electron optical system such as an electron beam exposure apparatus used for forming fine patterns in the manufacture of semiconductor integrated circuits and the like.

[Prior art]

Conventionally, the electron optical system of an electron beam exposure apparatus employs a spot beam using a single beam, a fixed shaped beam, and a variable shaped beam.

However, batan lithography using a single beam requires a long lithography time. For this reason, electron beam exposure equipment using these methods is suitable for LSI applications that require high-density pattern writing.
However, in order to improve throughput, a multi-beam system that simultaneously generates a large number of beams is promising.

However, even if a large number of beams are generated simultaneously, it is difficult to obtain a high beam current value for each beam by using an electron gun that generates a single beam. Therefore, an electron gun that generates multiple beams is required.

An electron gun that generates multiple beams can be constructed by simply arranging multiple ordinary single electron guns, but since the structure of the electron gun is large, it is difficult to arrange a large number of them at close intervals. Have difficulty. Therefore, as an arrangement of multiple electron guns arranged at narrow intervals, electron guns having four types of emitter chip structures shown in Figs. and
P, 11i1son: Vaccu+mVo1.30
No. 11/12 (1980) p, 527).

First, in FIG. 7, an emitter 18 made of an electron-emitting material such as tungsten is connected to a wire 1 made of tungsten or the like.
This is an emitter chip constructed by spot welding to 9.

The wire 19 fixes the emitter 18 and also serves as a heater.

Next, FIG. 8 shows an emitter chip in which the emitter 20 is inserted into a hole made in the emitter support material 21 and fixed. In this case, the emitter support material 21 is heated and the emitter 2
Heat 0.

Next, FIG. 9 shows that a conical portion is formed in the electron emitting material 22 by etching the surface of the electron emitting material 22 by chemical etching using the resist pattern 23 as a mask. An emitter chip is formed as an emitter 24 and then removed.

Next, in FIG. 10, a molybdenum mask 27 is first placed on a silicon substrate 25 with an insulating film 26 sandwiched therebetween.
form. A large number of minute holes are made in the molybdenum mask 27, and molybdenum, which is an emitter material, is deposited in a conical shape through the holes to form a field emission type emitter 30. The molybdenum mask 27 also serves as an extraction electrode. Note that before depositing molybdenum, aluminum 28 is vapor-deposited on the molybdenum mask 27, and the molybdenum deposit 2 remaining on the molybdenum mask 27 is
9 can be removed by etching the aluminum 28.

[Problem that the invention seeks to solve]

The conventional electron gun as described above has the following problems.

First, the electron gun shown in FIGS. 7 and 8 has a problem in that it is difficult to arrange the plurality of emitters 18, 20 at accurate intervals. Furthermore, when the spacing between the emitters 18, 20 becomes narrow, on the order of several hundred meters, it becomes difficult to fix the emitters to a wire or an emitter support.

On the other hand, in the electron guns of FIGS. 9 and 10, it is easy to accurately arrange the emitters 22, 30 at minute intervals. However, in the emitter chip of FIG. 9, the emitter shape is controlled by side etching that occurs during chemical etching, but it is difficult to accurately control the emitter shape by chemical etching. Therefore, it is difficult to process the emitter with good reproducibility.

Furthermore, with the emitter chip shown in Figure 1O, it is difficult to deposit emitter material with good reproducibility.Furthermore, when the emitter chip with the structure shown in Figure 10 is used as a thermionic electron gun, the emitter wears out due to evaporation of the emitter material. Because it is large,
If the emitter is not long enough, its life will be shortened. However, it is impractical to form long emitters by deposition because the emitter material must be deposited over a long period of time.

[Purpose of the Invention] The present invention has been made to solve the problems of the prior art as described above, and in order to enable faster baton drawing in a multi-beam type electron beam exposure apparatus, it is necessary to Another object of the present invention is to provide an electron gun having a multi-emitter that is highly accurate, highly durable, has an excellent thermionic emission effect, and is easy to manufacture.

[Means to solve bad luck]

In order to achieve the above object, in the present invention, in an electron gun equipped with an emitter tip made of an electron-emitting material and a Wehnelt electrode, on the surface of the emitter tip,
By forming grooves having side surfaces substantially perpendicular to the surface, a plurality of columnar emitters are formed on the surface of the emitter chip.

Note that the above-mentioned grooves are processed by, for example, a dicing saw or dry etching.

By configuring as described above, it is possible to realize a columnar multi-emitter whose shape, dimensions, and positional relationship are precisely set.

In addition, each emitter is columnar, and the thermionic emission surface is wider than the conical emitters shown in FIGS. 9 and 10, so the thermionic emission effect is excellent and the length of the column can be easily increased. It also has excellent durability.

Next, in another configuration of the present invention, in addition to the above configuration, the Wehnelt electrode is provided with the same number of openings as the number of emitters, and one of the above-mentioned emitters is arranged in each of the openings. are doing.

By configuring as described above, it is possible to give the same electric field distribution to each emitter surface.

The beam current obtained from each emitter surface can be made uniform.

[Embodiments of the invention]

An embodiment of the electron gun of the present invention will be shown below, and its structure and manufacturing method will be explained in detail.

FIG. 1 is a diagram showing an embodiment of the present invention, in which (A) is a perspective view of an emitter chip 1 provided with an emitter 2, and (B) is an electron-emitting material LaBG single crystal chip 1 serving as an emitter chip.
' is a perspective view of.

First, in Figure 1 (B), a single crystal of LaB is
, process it so that it becomes a prism at the corner, and then further.

The tip surface is processed to be flat by boring.

Next, as shown by the broken lines, two each in the vertical and horizontal directions.

By providing a total of four grooves 3, nine columnar emitters 2 are formed as shown in FIG. 1(A).

The emitter surface (the top surface of the pillar) is 1oon square, and the groove width is 20mm.
0. The emitters are arranged in a 3×3 arrangement with a 300-pitch. The height of each emitter is 300. shall be.

A method of fabricating such a multi-emitter will be described below.

A dicing saw is used to process the multi-emitter.

A dicing saw is commonly used to cut out semiconductor integrated circuit chips from a wafer using a thin blade.

Figure 2 shows a multi-emitter processing method using a dicing saw.

In FIG. 2(A), 1' is LaB, a single crystal chip,
4 is a blade of a dicing saw, and 5 is a cut groove. In addition, in Fig. 2 (B), 2' is the emitter surface, 5'
is the groove part, and arrow 6 is the cutting direction.

It is.

On the tip surface of the rectangular LaB single crystal chip 1',
Using a dicing saw, grooves 5 are cut as shown in Figure 2 (A).
Process. This gives 200-width, 300-depth. grooves are machined.

The blade 4 used in the dicing saw has a thickness thinner than the width of the groove to be machined. For example, a 100-thick blade may be used.

Dicing saws are equipped with a precision stage to move and position the workpiece.

LaB, single crystal chip 1' lost to precision stage.

A desired position of the LaB single crystal chip 1' can be processed with a dicing saw.

The direction in which the tip of the LaB single crystal chip 1' is cut with a dicing saw is as shown by the arrow 6 in FIG. 2(B).

The portion not cut off by the dicing saw remains as the emitter surface 2'.

By machining two vertical and two horizontal grooves as shown in the cutting direction 6, a 3×3 rectangular emitter surface is formed.

Each emitter is separated by a groove portion 5'.

FIG. 3 shows a method of fixing and heating the emitter chip formed as described above. Here, 1 is an emitter chip having a 3×3 rectangular emitter surface, 7.8 is a graphite block, and 9.10 is an electrode for electrical heating.

The two graphite blocks 7.8 sandwich the emitter chip 1 on the sides, and the graphite blocks 7.8
is held by fixing it with two electrical heating electrodes 9 and 10. Further, the emitter chip 1 is heated by Joule heat generated by passing a current through the graphite block 7.8 through the current heating electrode 9.10.

When the emitter chip 1 is heated, thermoelectrons are emitted from each emitter surface, resulting in a multi-beam.

Next, FIG. 4 shows the structure of a Wehnelt electrode used in an electron gun using a multi-emitter, where 2' is an emitter surface, 11 is a Wehnelt electrode plate, and 12 is a Wehnelt electrode hole.

The Wehnelt electrode is used for the purpose of controlling the emission current by adjusting the electric field applied to the emitter surface.

When using a multi-emitter, if only one Wehnelt electrode hole is used, the electric field applied to each emitter surface will not be the same, causing variations in the beam current values generated from each emitter surface. For this purpose, as shown in FIG.
2 so that the electric field on each emitter surface is the same.

Here, since there are 3×3 emitter surfaces, a Wehnelt electrode having 3×3 openings is used.

For the Wehnelt electrode 11, a molybdenum thin plate having a thickness of 50 to 1100 I1 is used. Thereafter, 3×3 openings each having a diameter of 2()O are formed at a pitch of 300 by etching or electrical discharge machining.

Next, other embodiments of the present invention will be described.

FIG. 5 is a diagram showing another embodiment of the multi-emitter processing method. Here, 1' is a LaB single crystal chip, 13 is a resist pattern, 14 is a groove, and 2' is an emitter surface.

First, a LaB single crystal chip 1' processed into a 700-square
Process the tip to be flat. This LaB, single crystal chip 1
Apply resist material to the tip of ′ and use photo exposure etc.
A button corresponding to the groove to be machined is exposed and developed.

As a result, a 3×3 resist button 13 as shown in FIG. 5(A) is formed. Thereafter, as shown in FIG. 5(B), dry etching is performed using the resist pattern 13 as a mask to form a groove 14 having substantially vertical side surfaces.

Next, as shown in FIG. 5(C), if the resist is peeled off,
A 3.times.3 emitter surface 2' is formed, resulting in a structure similar to that shown in FIG. 1(A).

By the way, since the T-a-B single-crystal chip 1' is as small as 700-square, it is difficult to apply a resist to the tip thereof.

Therefore, a resist is applied as shown in FIG. In FIG. 6, 17 is a resist film, 1' is LaB,
A single crystal chip, 15 a jig for fixing the chip, and 16 a hole for taking out the chip.

First, the LaB single crystal chip 1' is fixed to a disk-shaped chip fixing jig 15 with a rectangular hole in the center. La
The BG single crystal chip 1' is embedded in a hole in the center of the chip fixing jig 15, and is fixed so that there is no step difference between the surface of the chip to be processed and the surface of the chip fixing jig 15.

Next, a resist film 17 is formed by spin-coding a resist on the buried surface of the LaB single crystal chip 1'.

When taking out the LaB single crystal chip 1' from the chip fixing jig 15, it is sufficient to push the chip out using the hole 16 for taking out the chip.

In the above embodiments, LaBG was used as the electron emitting material, but other materials such as W and Ta may also be used.

Further, although the shape of the emitter is exemplified as a prismatic shape, as shown in FIG. 5, if dry etching is used, other shapes such as a cylindrical shape or a triangular prism shape can be used.

〔Effect of the invention〕

In the electron gun of the present invention, a plurality of emitters are formed by forming grooves in a single electron-emitting material, so that the following effects can be achieved. That is, since a single chip is used, chip heating can be performed in the same manner as in a conventional single-emitter electron gun, and the chip heating power does not increase. Therefore, compared to an electron gun using a plurality of chips, thermal deformation of parts constituting the electron gun can be reduced, and stability of beam characteristics can be improved. In addition, by using a dicing saw or dry etching to process the grooves, it is possible to obtain grooves with almost vertical sides, and it is easy to obtain a structure in which multiple emitters are arranged with high accuracy at minute intervals. It will be done.

In addition, each emitter is columnar, and the thermionic emission surface is wider than the conical emitters shown in FIGS. 9 and 10, so the thermionic emission effect is excellent and the length of the column can be easily increased. It also has excellent durability.

In addition, since the Wehnelt electrode has a Wehnelt electrode hole for each emitter, the same electric field distribution is given to each emitter surface, so the beam current obtained from each emitter surface can be made uniform. It has a positive effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of an emitter chip in an electron gun of the present invention, FIG. 2 is a diagram of an embodiment of the emitter chip processing method of the present invention, FIG. 3 is an installation diagram of the emitter chip, and FIG. The figure shows one embodiment of the Wehnelt electrode in the present invention, FIG. 5 shows another embodiment of the emitter chip processing method in the present invention, and FIG. 6 shows an explanatory diagram of the resist coating method.
FIGS. 7 to 10 are diagrams each showing an example of an emitter in a conventional electron gun. Explanation of symbols> 1...Emitter chip 1'...LaB, single crystal chip 2...Emitter 2'...Emitter surface 3...Groove 4...Dicing saw blade 5...Groove 5'... Groove portion 6... Cutting direction 7.8... Graphite block 9.10... Current heating electrode 11... Wehnelt electrode 12... Wehnelt electrode hole 13... Resist button 14... Groove 15... Chip fixing jig 16... Hole 17... Resist film Patent applicant Nippon Telegraph and Telephone Corporation Representative Patent Attorney Junnosuke Nakamura Figure 1 (B) Figure 2 ( A) (B) Figure 3, Figure 14, Figure 5, Figure O, Figure 6 ↑ Figure 7, Figure 8

Claims (1)

[Claims] 1. In an electron gun equipped with an emitter chip made of an electron-emitting material and a Wehnelt electrode, by forming a groove on the surface of the emitter chip with side surfaces substantially perpendicular to the surface. , An electron gun characterized in that a plurality of columnar emitters are formed on the surface of the emitter chip. 2. The electron gun according to claim 1, wherein the groove is machined with a dicing saw. 3. The electron gun according to claim 1, wherein the groove is formed by dry etching. 4. In an electron gun equipped with an emitter tip made of an electron-emitting material and a Wehnelt electrode, the surface of the emitter chip is improved by forming a groove having side surfaces substantially perpendicular to the surface of the emitter chip. A plurality of columnar emitters are formed in the electrode, and the Wehnelt electrode is provided with the same number of apertures as the number of emitters, and one of the emitters is disposed in each of the apertures. electron gun.