JP2006338958A - Electron beam light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron beam light source which can irradiate electrons having a uniform current density with respect to a wide area. <P>SOLUTION: The electron beam light source for irradiating an electron current EF against a target T, is provided with a plurality of number of electron guns 10 which are arranged two-dimensionally and which form electron beams EB, and a third grid 5 which forms the electron current EF, by making the current density have a Gaussian distribution and by making them overlapped. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electron beam light source used for an electron beam drawing apparatus, an electron beam irradiation apparatus, or the like.

  An electron beam drawing apparatus is known as a pattern transfer apparatus that does not use light. This electron beam drawing apparatus is an apparatus that irradiates an electron beam based on electronic data of a pattern and draws a pattern on an object such as a wafer or a mask.

  In this electron beam drawing apparatus, a VSB (variable shape beam) method in which an electron beam is shot on an object is often used. However, the VSB method has a problem that it takes time to draw and the throughput is poor.

  Therefore, in recent years, in order to realize high-speed drawing, a block drawing method for drawing a collection of fine patterns for each block has been developed. By the way, in this electron beam drawing apparatus, an electron gun composed of a light source of several microns is used as a means for generating an electron beam, and the electron beam from the electron gun is usually used after being enlarged by a lens. . Therefore, in the block drawing method in which drawing is performed for each block, it is necessary to further enlarge the electron beam, which causes non-uniformity in the beam current, extreme reduction in the amount of current, and the like. For this reason, the electron beam drawing apparatus cannot use a beam from a single electron light source as an illumination optical system, so that the electron drawing becomes low-dose and there is a problem in throughput.

  An electron beam irradiation apparatus is known as a surface treatment apparatus that does not use light. This electron beam irradiation apparatus is an apparatus that irradiates an object to be processed such as a film placed in the atmosphere with an electron beam to modify the surface of the object to be processed (see, for example, Non-Patent Document 1). The electron beam irradiation apparatus is also applied to manufacturing processes in various industrial fields such as ink drying and overcoat resin curing.

There are several types of electron beam irradiation devices, such as a vacuum tube type electron beam irradiation device that extracts electrons with a vacuum tube, and an acceleration tube type electron beam irradiation device that extracts electrons emitted from a linear filament with an acceleration tube. . Although the object to be processed is processed by moving the object to be processed with respect to these round or linear electron beams, it is difficult to control to obtain an electron beam with a uniform current density.
Mizushima Yasumori, “Painting Technology”, Riko Publishing Co., Ltd., October / October 2001, p. 90-96

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an electron beam light source capable of irradiating electrons with a uniform current density over a wide area.

  In order to solve the above problems and achieve the object, the electron beam light source of the present invention is configured as follows.

(1) In an electron beam light source for irradiating an electron current to a target, a plurality of electron guns that are two-dimensionally arranged to form an electron beam, and a current density of the electron beam formed by the electron gun is a Gaussian distribution, Electron current forming means for forming the electron current by overlapping them is provided.

(2) In the electron beam light source described in (1), the electron flow forming unit overlaps the plurality of electron beams by setting an imaging point of the electron beam upstream of the target.

(3) In the electron beam light source described in (1), the electron guns are arranged in a staggered pattern.

(4) The electron beam light source described in (1) includes shaping means for shaping a cross-sectional shape of the electron flow.

(5) In the electron beam light source described in (1) or (2), the electron flow forming means includes a grid having a plurality of openings through which an electron beam formed by the electron gun passes, and the grid And a voltage applying means for controlling the electron beam by applying a lens action to the electron beam passing through the opening by the grid.

(6) In the electron beam light source described in (5), the voltage applying unit applies a driving voltage to the plurality of electron guns.

  According to the present invention, electrons can be irradiated with a uniform current density over a wide area.

FIG. 1 is a schematic diagram of an electron beam light source according to an embodiment of the present invention, and FIG. 2 is a first example of a first grid 3, a second grid 4, a third grid 5, and an anode 6 according to the embodiment. FIG. 3 is a diagram illustrating a second example of the first grid 3, the second grid 4, the third grid 5, and the anode 6 according to the embodiment.
As shown in FIG. 1, the electron beam light source includes a heater 1, a cathode 2, a first grid 3, a second grid 4, a third grid 5, an anode 6, an aperture 7, and a control circuit 8. Reference symbol T is a target of the electron flow EF formed by this electron beam light source.

Hereinafter, each component will be described.
The heater 1 includes a filament 1 a and heats the cathode 2 by applying a voltage from the control circuit 8. The cathode 2 has a rectangular or circular plate shape, and emits electrons e from the surface opposite to the heater 1 by heating from the heater 1. As the material of the cathode 2, a metal such as tungsten is used.

  The first grid 3, the second grid 4, the third grid 5, and the anode 6 have a circular or rectangular plate shape (see FIGS. 2 and 3), and a plurality of openings 3a and 4a are formed as a whole. 5a and 6a are two-dimensionally arranged at a uniform density. In addition, as a method for arranging the openings 3a, 4a, 5a, and 6a, a so-called staggered arrangement that can increase the density of the openings is employed.

  The second grid 4 extracts electrons e emitted from the cathode 2 to the target T side by a positive voltage applied from the control circuit 8. The first grid 3 suppresses and converges the electrons e drawn to the target T side by a negative voltage applied from the control circuit 8 to form an electron beam EB. That is, the current amount of the electron beam EB is adjusted by the voltage balance between the first grid 3 and the second grid 4.

  The amount of current of the electron beam EB is not only the voltage balance of the first and second grids 3 and 4 but also the interval between the first and second grids 3 and 4 and the openings provided in the grids 3 and 4. Also affected by the inner diameters of 3a and 4a.

  As a result of experiments by the inventor, a stable electron beam of about 50 μA per electron gun 10 is obtained if the distance between the first and second grids 3 and 4 is 0.3 mm and the inner diameter of the openings 3a and 4a is 0.4 mm. EB could be obtained. Therefore, if the number of electron guns 10 is increased, a stable electron beam EB having a large current can be obtained.

  The anode 6 accelerates the electrons that have passed through the first grid 3 toward the target T by the ground voltage applied from the control circuit 8. That is, a plurality of two-dimensionally arranged electron guns 10 according to the present invention includes the heater 1, the cathode 2, the first grid 3, the second grid 4, and the anode 6.

  The third grid 5 narrows down the electron beam EB by the negative voltage applied from the control circuit 8, sets the imaging point C upstream of the target T, and makes the current density Gaussian distribution. As a result, the plurality of electron beams EB that have passed through the anode 6 suddenly expand downstream of the imaging point C, and the outer peripheral portion and the outer peripheral portion overlap each other, whereby the current density is uniform and the area is large. Electron current EF is formed.

  As shown in FIG. 1, the aperture 7 includes an opening 7a, blocks the peripheral edge of the electron current EF, and shapes its cross-sectional shape to the same shape as the opening 7a. Thereby, even if an unnecessary corrugation etc. exists in the peripheral part of the electron stream EF, the target T can be irradiated with the electron stream EF having a desired shape.

  The control circuit 8 is connected to the filament 1a, the cathode 2, the first grid 3, the second grid 4, the third grid 5 and the anode 6 of the heater 1, and applies a predetermined DC voltage to these. Yes.

Next, the formation process of the electron stream EF by the electron beam light source will be described.
When the cathode 2 is heated by the heater 1, many electrons e are emitted from the cathode 2. The electrons e are drawn to the target T side by the third grid 4 and converged by the first grid 3 to become an electron beam EB.

  The electron beam EB is accelerated by the voltage between the first grid 3 and the anode 6, travels toward the target T, and is narrowed by the third grid 5 in the middle thereof. As a result, an imaging point C is formed upstream of the target T, and the focus dimension of the electron beam EB on the target T is expanded, so that the base of the plurality of electron beams EB overlaps the target T. A large area electron stream EF is irradiated.

4 is a current density distribution diagram of each electron beam EB according to the embodiment, and FIG. 5 is a current density distribution diagram of the electron current EF according to the embodiment.
As shown in FIG. 4, the current density of each electron beam EB has a Gaussian distribution. When these are overlapped, as shown in FIG. EF can be obtained. Therefore, if the electron beam light source according to the present embodiment is used, the target T can be irradiated with the electron current EF having a uniform current density.

  According to the electron beam light source according to the present embodiment, the plurality of electron guns 10 are two-dimensionally arranged. The current density of the electron beam EB from each electron gun 10 is a Gaussian distribution, and these are overlapped to form a large area electron flow EF.

  Therefore, the electron current EF having a uniform current density can be irradiated to a large area, so that it is possible to realize block drawing by an electron beam, which has been difficult in the past, and to shorten the time of various processings by the electron beam. it can.

  Moreover, even though a plurality of electron guns 10 are used, only one control circuit for controlling the electron gun 10 and the third grid 5 is sufficient, so that the electrical wiring can be simplified and the device configuration can be reduced in size. can do.

  Further, according to the electron beam light source according to the present embodiment, the imaging point C of the electron beam EB is created upstream of the target T, and the focus dimension on the target T is controlled. Therefore, it is possible to synthesize the current density distribution of Gaussian and form a flat current density distribution with extremely simple control.

  Furthermore, according to the electron beam light source according to the present embodiment, a so-called staggered arrangement is adopted as the arrangement method of the electron guns 10. Therefore, the current density of the electron current EF can be increased.

  Moreover, according to the electron beam light source which concerns on this embodiment, the aperture 7 which shapes the cross-sectional shape of the electron stream EF is provided. Therefore, even if the shape of the outer edge portion of the electron flow EF becomes corrugated due to the influence of the outermost electron gun 10 among the plurality of electron guns 10, the shape of the aperture 7 can be selected by selecting the shape of the aperture 7. Can be irradiated with an electron current EF having a desired shape.

  In the present embodiment, the shapes of the cathode 2, the first grid 3, the second grid 4, the third grid 5, and the anode 6 are circular or rectangular. However, the present invention is not limited to this, and finally It can be selected according to the cross-sectional shape of the electron current EF to be obtained.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

Schematic of the electron beam light source which concerns on one Embodiment of this invention. FIG. 3 is a representative view of a first grid, a second grid, a third grid, and an anode according to the embodiment. The figure which shows the 2nd example of the 1st grid, 2nd grid, 3rd grid, and anode which concern on the embodiment. The distribution diagram of the current density of each electron beam according to the embodiment. The distribution diagram of the current density of the electron current concerning the embodiment.

Explanation of symbols

  5 ... Third grid (grid), 5a ... Opening, 7 ... Aperture (shaping means), 8 ... Control circuit (voltage applying means), 10 ... Electron gun, T ... Target, e ... Electron, EB ... Electron beam, EF ... electron flow, C ... imaging point.

Claims (6)

In an electron beam light source for irradiating a target with an electron stream,
A plurality of electron guns arranged two-dimensionally to form an electron beam;
Electron current forming means for forming the electron current by making the current density of the electron beam formed by the electron gun a Gaussian distribution and overlapping them,
An electron beam light source comprising:   The electron beam light source according to claim 1, wherein the electron flow forming unit overlaps the plurality of electron beams by setting an imaging point of the electron beam upstream of the target.   The electron beam light source according to claim 1, wherein the electron guns are arranged in a staggered pattern.   The electron beam light source according to claim 1, further comprising a shaping unit that shapes a cross-sectional shape of the electron flow. The electron flow forming means includes
A grid having a plurality of openings through which an electron beam formed by the electron gun passes;
Voltage application means for controlling the electron beam by applying a lens action to the electron beam passing through the opening by the grid by applying a control voltage to the grid;
The electron beam light source according to claim 1, further comprising:   The electron beam light source according to claim 5, wherein the voltage applying unit applies a driving voltage to the plurality of electron guns.

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