JP2006012530A - Electron gun cathode structure, electron gun cathode structure manufacturing method, and electron gun - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cathode structure of an electron gun, a manufacturing method of the same, and an electron gun of which, heat radiation to a shielding member side is unprecedentedly sharply reduced. <P>SOLUTION: On the cathode structure of the electron gun formed by inserting the cathode member emitting electron from an electron emission face by the heating of a heating face into the shielding member shielding the electron emitted from the outer periphery of the cathode member, prescribed gaps are formed between a hole part of the shielding member and outer periphery of the cathode member, and a plurality of protrusions for fitting, holding the cathode member on the shielding member by fitting into either the outer periphery of the cathode member or the hole part of the shielding member, are formed at the hole part of the shielding member or at the outer periphery of the cathode part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cathode structure for an electron gun and a method for manufacturing the same. The present invention also relates to an electron gun used in an electron beam exposure apparatus or the like.

In recent years, electron beam exposure apparatuses capable of exposing finer semiconductor integrated circuits have been actively developed. In such an electron beam exposure apparatus, since the exposure area is about 250 μm, which is very large compared to other electron beam drawing apparatuses, an electron gun having a high emittance capable of uniformly illuminating the field is required.
Conventionally, as such an electron gun, for example, one disclosed in JP-A-10-223166 is known.

In this electron gun, the cathode structure is composed of a cathode member that emits electrons from the electron emission surface by heating the heating surface, and a shielding member that shields electrons emitted from the outer periphery of the cathode member. A shielding member is in close contact with the outside of the cathode member.
JP-A-10-223166

However, the conventional cathode structure has a problem in that the heat of the cathode member escapes to the shielding member side because the shielding member is in close contact with the outside of the cathode member.
The present invention has been made to solve such a conventional problem, and provides a cathode structure for an electron gun and a method for manufacturing the same that can significantly reduce the heat release to the shielding member side as compared with the prior art. Objective. It is another object of the present invention to provide an electron gun using the cathode structure of the present invention.

  The cathode structure of an electron gun according to claim 1, wherein a cathode member that emits electrons from an electron emission surface by heating the heating surface is inserted into a hole of a shielding member that shields electrons emitted from the outer periphery of the cathode member. A predetermined gap is formed between the hole of the shielding member and the outer periphery of the cathode member, and the cathode member is formed in the hole of the shielding member or the outer periphery of the cathode member. And a plurality of fitting protrusions for holding the cathode member on the shielding member.

  The cathode structure of the electron gun according to claim 2 is the cathode structure of the electron gun according to claim 1, wherein the cathode member is formed by a cylindrical large diameter portion on which the heating surface is formed and the electron emission surface. A large-diameter hole in which the large-diameter portion is disposed with a predetermined gap and a small-diameter hole in which the small-diameter portion is disposed with a predetermined gap. The cathode member is held by the shielding member by fitting the large-diameter hole of the shielding member or the large-diameter portion of the cathode member into the large-diameter portion of the cathode member or the large-diameter hole of the shielding member. And forming a predetermined gap between the step surface forming the large diameter portion and the small diameter portion and the step surface forming the small diameter hole and the large diameter hole. , The electron emission surface of the cathode member and the electricity of the shielding member. A discharge-side end face of the emission surface side is positioned on the same plane, characterized by comprising.

The cathode structure of an electron gun according to claim 3 is the cathode structure of the electron gun according to claim 1 or 2, wherein the cathode member is made of a tantalum single crystal having a plane orientation of (111), and the shielding. The member is characterized by comprising a tantalum single crystal having a (110) plane orientation.
5. The method of manufacturing a cathode structure for an electron gun according to claim 4, wherein a cylindrical cathode member that emits electrons from an electron emission surface by heating the heating surface is shielded from electrons emitted from an outer peripheral portion of the cathode member. A plurality of fitting protrusions that are inserted into the cylindrical hole portion of the member and project from the hole portion of the shielding member or the outer periphery of the cathode member are formed on the outer periphery of the cathode member from the outer diameter of the cathode member A first fitting portion that is formed in a temporary fitting portion having a small diameter or a hole portion of the shielding member and is fitted in a temporary fitting portion having a diameter larger than the inner diameter of the hole portion, and holds the cathode member in the hole portion of the shielding member. And the electron emission surface of the cathode member and the emission side end surface of the shielding member on the electron emission surface side are processed so that the electron emission surface and the emission side end surface are located on the same plane. Processing step and the cathode member A foreign matter removing step of separating the shield member from the foreign matter, and fitting the fitting protrusion into the large diameter portion of the cathode member or the large diameter hole of the shielding member at a position other than the temporary fitting portion, And a second assembling step of positioning the electron emission surface and the emission side end surface on the same plane.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a cathode structure for an electron gun according to the fourth aspect, wherein the processing in the processing step is polishing.
An electron gun according to claim 6, comprising the cathode structure of the electron gun according to any one of claims 1 to 3.

In the cathode structure of the electron gun of the present invention, the cathode member is held on the shielding member by the plurality of fitting protrusions, and a predetermined gap is formed between the cathode member and the shielding member. The contact area becomes smaller, and heat release to the shielding member side can be greatly reduced as compared with the conventional case.
In the method for manufacturing a cathode structure for an electron gun according to the present invention, in the first assembly step, the fitting protrusion is fitted to the temporary fitting portion to hold the cathode member on the shielding member, In the assembling step, the fitting protrusion is fitted at a position other than the temporary fitting portion and the cathode member is held by the shielding member, so that the cathode member is securely held by the shielding member by the fitting protrusion. be able to.

  The electron gun of the present invention can provide a high-performance electron gun because heat release from the cathode member to the shielding member side is reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
1 and 2 show a first embodiment of the cathode structure of the electron gun of the present invention.
This cathode structure has a cathode member 11 and a shielding member 13.
As shown in FIG. 2, the cathode member 11 is made of a tantalum single crystal whose electron emission surface 11b has a (111) plane orientation, and the shielding member 13 has a (110) plane tantalum whose emission side end surface 13e has a (110) plane orientation. It consists of a single crystal.

As shown in FIG. 2, a heating surface 11a is formed on one surface of the cathode member 11, and an electron emission surface 11b that emits electrons by heating the heating surface 11a is formed on the other surface.
The shielding member 13 is disposed so as to surround the cathode member 11 and shields electrons emitted from the outer periphery of the cathode member 11.
In this embodiment, the cathode member 11 includes a cylindrical large-diameter portion 11c (for example, a diameter of 8 mm) where the heating surface 11a is formed, and a cylindrical small-diameter portion 11d (for example, a diameter of 4 mm) where the electron emission surface 11b is formed. And have. A flat cathode member side step surface 11e is formed on the small diameter portion 11d side of the large diameter portion 11c.

  Further, the shielding member 13 includes a large-diameter hole 11a in which the large-diameter portion 11c of the cathode member 11 is disposed with a predetermined gap of, for example, about 20 to 30 μm, and a small-diameter portion 11d of the cathode member 11 in, for example, 20 And a small-diameter hole 13b disposed with a predetermined gap of about 30 μm. And the planar shielding member side level | step difference surface 13c is formed in the small diameter hole 13b side of the large diameter hole 13a.

The cathode member side step surface 11e and the shielding member side step surface 13c are arranged to face each other with a predetermined gap of about 100 to 200 μm, for example.
In this embodiment, as shown in FIG. 1, the large-diameter hole 13 a of the shielding member 13 is formed with fitting protrusions 13 d at four positions with an angle of 90 degrees.
A temporary fitting portion 11 f having a smaller diameter than the outer diameter of the cathode member 11 is formed on the outer periphery of the cathode member 11. In this embodiment, the temporary fitting part 11f is formed in the outer periphery of the cathode member 11 by forming a micro recessed part of 10-20 micrometers, for example. The temporary fitting portion 11f is formed so that the fitting projection 13d can be fitted in correspondence with the fitting projection 13d, and holds the cathode member 11 on the shielding member 13 in a first assembly step described later. Used for.

  In this embodiment, as shown in FIG. 1, the fitting protrusion 13 d of the shielding member 13 is fitted to the large-diameter portion 11 c of the cathode member 11 at a position other than the temporary fitting portion 11 f of the cathode member 11. The cathode member 11 is held by the shielding member 13. In addition, as shown in FIG. 2, the electron emission surface 11b of the cathode member 11 and the emission side end surface 13e on the electron emission surface 11b side of the shielding member 13 have an accuracy with which the electron emission surface 11b protrudes by, for example, about 0 to 5 μm. Are located on the same plane.

The cathode structure of the electron gun described above is manufactured as described below according to an embodiment of the method for manufacturing a cathode structure of an electron gun of the present invention.
The manufacturing method of this embodiment has a first assembly step, a processing step, a foreign matter removal step, and a second assembly step.
First, in the first assembly step, the cathode member 11 is assembled to the shielding member 13 as shown in FIG. This assembly is performed by fitting the fitting protrusion 13d of the shielding member 13 to the temporary fitting portion 11f formed on the outer periphery of the cathode member 11 in a slightly press-fitted state. By this fitting, the cathode member 11 is held by the shielding member 13. In this state, between the large diameter hole 13a of the shielding member 13 and the large diameter portion 11c of the cathode member 11, between the small diameter hole 13b of the shielding member 13 and the small diameter portion 11d of the cathode member 11, and the cathode member. A predetermined gap is formed between the side step surface 11e and the shielding member side step surface 13c.

  Next, in the processing step, the electron emission surface 11b of the cathode member 11 and the emission side end surface 13e on the electron emission surface 11b side of the shielding member 13 are simultaneously polished. By this polishing process, the electron emission surface 11b and the emission side end surface 13e are positioned on the same plane. In this embodiment, the heating surface 11a of the cathode member 11 and the end surface 13f (shown in FIG. 3B) of the shielding member 13 on the heating surface 11a side are polished and positioned on the same plane as the reference surface. Is done.

Next, in the foreign matter removing step, the cathode member 11 is separated from the shielding member 13 to remove the foreign matter.
That is, in the above-described processing steps, foreign particles such as loose abrasive grains and polishing scraps used in the polishing process enter the gap between the shielding member 13 and the cathode member 11, and these foreign materials are a means such as ultrasonic cleaning. It is difficult to completely remove even if is used. Therefore, in order to remove such foreign matter, the cathode member 11 is separated from the shielding member 13, and the foreign matter is removed by cleaning or the like.

Next, in the second assembly step, as shown in FIG. 1, the fitting protrusion 13d of the shielding member 13 is fitted to the large diameter portion 11c of the cathode member 11 at a position other than the temporary fitting portion 11f. The electron emission surface 11b and the emission side end surface 13e are positioned on the same plane.
That is, when the shielding member 13 and the cathode member 11 are disassembled for cleaning in the foreign matter removing process described above, the contact portions between the fitting projection 13d and the temporary fitting portion 11f are worn away, and the fitting projection 13d The fitting with the temporary fitting portion 11f is loosened. And even if it fits again, the level | step difference of the electron emission surface 11b and the emission side end surface 13e becomes large by the vibration, impact, etc. by subsequent handling. Therefore, in this embodiment, the fitting protrusion 13d of the shielding member 13 is fitted to the large diameter portion 11c of the cathode member 11 at a position other than the temporary fitting portion 11f. Thus, loosening of the fitting between the fitting protrusion 13d and the temporary fitting portion 11f is avoided. In this embodiment, since the heating surface 11a of the cathode member 11 and the end surface 13f on the heating surface 11a side of the shielding member 13 polished in the above-described processing steps are assembled as a reference surface, the electron emission surface 11b and the emission side are assembled. The end surface 13e is positioned on the same plane with an accuracy that the electron emission surface 11b protrudes by, for example, about 0 to 5 μm.

In the cathode structure of the electron gun of this embodiment, the cathode member 11 is held on the shielding member 13 by the plurality of fitting protrusions 13d, and a predetermined gap is formed between the cathode member 11 and the shielding member 13. The contact area between the cathode member 11 and the shielding member 13 is reduced, and heat release to the shielding member 13 side can be significantly reduced as compared with the prior art.
Moreover, in the manufacturing method of the cathode structure of the electron gun of this embodiment, the fitting protrusion 13d is fitted to the temporary fitting portion 11f and the cathode member 11 is held by the shielding member 13 in the first assembly step. In the second assembly step, the fitting projection 13d is fitted at a position other than the temporary fitting portion 11f and the cathode member 11 is held by the shielding member 13, so that the fitting projection 13d The cathode member 11 can be reliably held on the shielding member 13.

In the cathode structure of the electron gun of the above-described embodiment, the cathode member 11 is formed of a tantalum single crystal having a (111) plane orientation, and the shielding member 13 is a single tantalum having a (110) plane orientation. Since it is formed of crystals, an electron gun with high emittance that can uniformly illuminate the inside of the field can be obtained.
That is, conventionally, in order to obtain an electron gun with high emittance, a technique for heating a tantalum single crystal having a large diameter by electron bombardment has been proposed. In this technique, the (111) plane of a tantalum single crystal having a diameter of 4 mm is polished, and the heating surface 11a is heated to emit thermoelectrons from the electron emission surface 11b. The work function of the (111) plane of the tantalum single crystal is as low as 4.05 eV and is likely to emit thermal electrons.

  However, if the cathode structure is composed only of a tantalum single crystal (111) having a diameter of 4 mm, a considerable amount of electrons are emitted from the side surface, and an excessive heat load is applied to the aperture and the like. Therefore, as in the embodiment described above, if the outside of the tantalum single crystal (111) is covered with the tantalum single crystal (110) having a work function as high as 4.8 eV, no extra electrons will be emitted, and the contact between the two will be avoided. If the area is made as small as possible, large heat will not escape, so that high temperature uniformity of the electron emission surface 11b of the cathode structure can be achieved.

  Also, if the step between the electron emission surface 11b of the tantalum single crystal (111) and the emission side end surface 13e of the tantalum single crystal (110) is large, the electrostatic field near the diameter of 4 mm is distorted, and the orbit of the emitted electrons from this portion is It will bend outwards, adversely affecting lighting uniformity. Therefore, as in the above-described embodiment, by suppressing the step of this portion to 10 μm or less, preferably 0 to 5 μm, it is possible to prevent the emitted electron trajectory from being bent outward.

In this embodiment, since the cathode member 11 and the shielding member 13 are formed of a tantalum single crystal, the thermal expansion coefficients of the cathode member 11 and the shielding member 13 are the same, and the illumination uniformity can be further improved. .
(Second Embodiment)
FIG. 4 shows a second embodiment of the cathode structure of the electron gun of the present invention.

In this embodiment, the same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In this embodiment, the outer periphery of the cathode member 11 is formed with four fitting protrusions 11h at an angle of 90 degrees.
Further, the large-diameter hole 13a of the shielding member 13 is formed with a temporary fitting portion 13h having a diameter larger than that of the large-diameter hole 13a. In this embodiment, the temporary fitting part 13h is formed in the large diameter hole 13a of the shielding member 13 by forming a micro recessed part of 10-20 micrometers, for example. The temporary fitting portion 13h is formed so that the fitting projection 11h can be fitted to the fitting projection 11h. And this temporary fitting part 13h is used in order to hold | maintain the cathode member 11 in the shielding member 13 in a 1st assembly | attachment process similarly to 1st Embodiment.

Also in this embodiment, substantially the same effect as that of the first embodiment can be obtained.
In the first and second embodiments described above, the example in which the fitting protrusions 13d and 11h and the temporary fitting portions 11f and 13h are formed at four positions has been described. However, the present invention is limited to such an embodiment. What is necessary is just three or more places.
In the first and second embodiments described above, the example in which the temporary fitting portions 11f and 13h are formed by minute recesses has been described. However, the present invention is not limited to such an embodiment. It may be formed by cutting out in a plane.

In the first and second embodiments described above, the example in which the tantalum single crystal is used for the cathode structure has been described. However, the present invention is not limited to the embodiment, and for example, tungsten, molybdenum, and the like. May be used.
(Embodiment of electron gun)
FIG. 5 shows an embodiment of the electron gun of the present invention.

The electron gun of this embodiment has the cathode structure 21, Wehnelt 23, anodes 25, 27 and 29, and a gun aperture 31 shown in FIGS. 1 and 2.
In the electron gun of this embodiment, the primary electron beam emitted from the electron emission surface 11b of the cathode structure 21 is in the vicinity between the Wehnelt 23 and the first anode 25 due to the influence of the negative suppression voltage applied to the Wehnelt 23. The first crossover 33 is formed by squeezing. Then, by adjusting the voltages of the second anode 27 and the third anode 29, the position of the second crossover 35, which is formed by reducing the primary electron beam again, is adjusted to the position of the gun aperture 31.

  In the electron gun of this embodiment, since heat emission from the cathode member 11 to the shielding member 13 side is reduced, a high-performance electron gun can be provided.

It is a top view which shows 1st Embodiment of the cathode structure of the electron gun of this invention. It is sectional drawing which shows the cathode structure of the electron gun of FIG. It is explanatory drawing which shows the manufacturing method of the cathode structure of the electron gun of FIG. It is explanatory drawing which shows 2nd Embodiment of the cathode structure of the electron gun of this invention. It is explanatory drawing which shows one Embodiment of the electron gun of this invention.

Explanation of symbols

11 Cathode member 11a Heating surface 11b Electron emission surface 11c Large diameter portion 11d Small diameter portion 11e Cathode member side step surface 11f, 13h Temporary fitting portion 13 Shielding member 13a Large diameter hole 13b Small diameter hole 13c Shielding member side step surface 13d, 11h Collision 13e discharge side end face

Claims (6)

In the cathode structure of the electron gun formed by inserting the cathode member that emits electrons from the electron emission surface by heating the heating surface into the hole of the shielding member that shields electrons emitted from the outer periphery of the cathode member,
A predetermined gap is formed between the hole portion of the shielding member and the outer periphery of the cathode member, and at the hole portion of the shielding member or the outer periphery of the cathode member, the outer periphery of the cathode member or the hole portion of the shielding member. A cathode structure for an electron gun comprising a plurality of fitting protrusions that are fitted to hold the cathode member on the shielding member. The cathode structure of the electron gun according to claim 1,
The cathode member is formed of a cylindrical large-diameter portion where the heating surface is formed and a cylindrical small-diameter portion where the electron emission surface is formed, and the large-diameter portion is formed in the shielding member with a predetermined gap. Forming a large-diameter hole and a small-diameter hole in which the small-diameter portion is arranged with a predetermined gap,
A plurality of fits for fitting the large-diameter portion of the cathode member or the large-diameter hole of the shielding member into the large-diameter hole of the shielding member or the large-diameter portion of the cathode member and holding the cathode member on the shielding member. A predetermined gap is formed between the step surface forming the projecting portion, the step surface forming the large diameter portion and the small diameter portion, and the step surface forming the small diameter hole and the large diameter hole,
A cathode structure for an electron gun, wherein the electron emission surface of the cathode member and the emission side end surface of the shielding member on the electron emission surface side are positioned on the same plane. The cathode structure of the electron gun according to claim 1 or 2,
The cathode structure of an electron gun, wherein the cathode member is made of a tantalum single crystal having a plane orientation of (111), and the shielding member is made of a tantalum single crystal having a plane orientation of (110). A cylindrical cathode member that emits electrons from the electron emission surface by heating the heating surface is inserted into a cylindrical hole of the shielding member that shields electrons emitted from the outer peripheral portion of the cathode member, and the shielding member A plurality of fitting protrusions that protrude from the outer periphery of the hole or the cathode member are formed in the temporary fitting portion formed on the outer periphery of the cathode member and having a smaller diameter than the outer diameter of the cathode member or the hole of the shielding member. A first assembly step of fitting the temporary fitting portion having a diameter larger than the inner diameter of the hole portion and holding the cathode member in the hole portion of the shielding member;
Processing the electron emission surface of the cathode member and the emission side end surface of the shielding member on the electron emission surface side to position the electron emission surface and the emission side end surface on the same plane;
A foreign matter removing step of separating the cathode member from the shielding member and removing foreign matter;
The fitting protrusion is fitted into the large-diameter portion of the cathode member or the large-diameter hole of the shielding member at a position other than the temporary fitting portion, and the electron emission surface and the emission side end surface are flush with each other. A second assembly step for positioning;
A method for manufacturing a cathode structure of an electron gun, comprising: In the manufacturing method of the cathode structure of the electron gun of Claim 4,
The method of manufacturing a cathode structure of an electron gun, wherein the processing in the processing step is polishing processing.   An electron gun comprising the cathode structure for an electron gun according to any one of claims 1 to 3.

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