JPH077649B2 - Electron gun - Google Patents

Description

The present invention relates to electron guns, and more particularly to electron guns for electron beam evaporation.

(Prior Art) An electron gun generates an electron beam and is used in an electron microscope, an electron beam drawing apparatus, and the like. In this type of apparatus, a sample is irradiated with an electron beam emitted from an electron gun, a reflected signal thereof is captured and reproduced as an image, or a beam itself exposes a material such as a wafer.

By the way, the ratio of energy to the incident beam of the reflected electron signal that irradiates and reflects the material varies depending on the material (sample), and there is a thing (tungsten, etc.) that increases as the atomic number Z increases, such as tungsten. Most of the energy produced becomes heat. This heat can generate heat at a density of 1,000,000 KW / cm ² if the beam is narrowed down. Therefore, when a sample (material) such as metal is irradiated with such an electron beam, the surface of the sample (material) such as metal can be melted and evaporated. The vacuum vapor deposition apparatus is an apparatus for performing metal vapor deposition on a substance surface by utilizing the evaporation phenomenon of a material such as a metal by such an electron beam.

FIG. 5 is a diagram showing an example of a conventional structure of an electron gun used for the vacuum vapor deposition as described above. In the figure, reference numeral 1 denotes a linear filament that forms a cathode. A common potential (in the case of a DC power source, a negative electrode) of the acceleration power source 2 and the filament power source 3 is applied to one end of the filament 1. Since the positive polarity side of the acceleration power supply 2 is grounded, a very high negative voltage (acceleration voltage) is applied to the filament 1. Reference numeral 4 denotes a beam shaping electrode (grid) arranged to face each other along the filament 1, to which a negative side potential of a grid power source 5 whose positive side is connected to a negative side of the acceleration power source 2 is applied.

The positive electrode side of the filament power source 3 is connected to the other end of the filament 1. Reference numeral 6 denotes a beam accelerating electrode (anode) arranged to face the filament 1 and is grounded. A slit 6a for passing the generated electron beam is provided at the center of the beam accelerating electrode 6. 8 is a metal (sample) for metal vapor deposition, 9 is a crucible containing the metal 8, and cooling water 10 is circulated at the bottom thereof.
The crucible 9 is grounded.

In the device configured as described above, when a current is passed from the filament power supply 3 to the linear filament 1, the filament 1 generates heat and emits thermoelectrons. The generated thermoelectrons pass through the slit 6a of the beam acceleration electrode 6 and are accelerated. In the device shown in the figure, a magnetic field B in the direction of the arrow is generated by a magnetic field generator (for example, a ring coil) not shown, and the electrons passing through the slit 6a receive a force according to Fleming's left-hand rule, The beam locus is rotated to collide with the bundled electron beam Bi so as to form a linear spot on the surface of the metal 8 in the crucible 9.

Then, the portion where the electron beam Bi collides is gradually heated, the metal is melted, and vaporization of the metal occurs. Here, the generated metal vapor is extremely fine particles at the atomic or molecular level. As described above, metal deposition can be performed by disposing a deposition target member (for example, glass, metal, etc.) on the upper portion in a vacuum where the metal is evaporated.

(Problems to be Solved by the Invention) The above electron gun (linear filament type electron gun. LFG, hereinafter) in which a grid and an anode are arranged in parallel on a linear filament.
In order to increase the output, the filament is lengthened and the shape (length) of the linear spot on the electron beam irradiation surface is increased by using the electron optical lens. But the filament is long (number
In the case of 10 mm or more), the use of a normal axisymmetric electro-optical lens causes a considerable increase in the size of the device, which causes considerable structural difficulties (the beam deflection angle is the bending angle of the emitted beam). (See Fig. 6).

The present invention has been made in view of such points,
The purpose thereof is to realize an electron gun capable of lengthening the spot shape on the irradiation surface without using an electro-optical lens when increasing the output.

(Means for Solving the Problems) The present invention for solving the above problems is an electron gun having a linear filament, a grid and an anode arranged in parallel with the filament, and the filament, the grid and the anode. The anode is curved in a convex shape toward the emission direction of the electron beam so that the electron beam is emitted substantially radially, and the electron beam emitted from the filament is deflected by a magnetic field in the same direction as the longitudinal direction of the filament. It is characterized in that a linear spot is formed on the electron beam irradiation surface.

(Operation) In the electron gun of the present invention, since the filament, the grid and the anode are curved in a convex shape toward the emission direction of the electron beam, the electron beam is substantially radial from the filament 1 as shown in FIG. Go out to spread. The electron beam emitted from the filament 1 is deflected by a magnetic field in a direction substantially the same as the longitudinal direction of the filament, and a long linear spot is formed on the electron beam irradiation surface even though no electron optical lens is used. To be done.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a mechanical block diagram showing an embodiment of the present invention.
The same parts as those in FIG. 5 are designated by the same reference numerals. still,
In the figure, the power supply and its potential connection diagram are omitted. As is apparent from the figure, the structure of the electrode system is the same as that of the conventional example shown in FIG. The only difference is the filament except the crucible 9.
1, the beam shaping electrode 4 and the beam accelerating electrode 6 are all arranged on a concentric circle centered on the point 0.
That is, the filament 1, the beam shaping electrode 4, and the beam accelerating electrode 6 form a part of a circle centered on the point 0, that is, an arc.

FIG. 2 is a diagram schematically showing the arrangement of the electrode system.
As described above, the respective electrodes (cathode 1, grid 4, anode 6) are present on the concentric circles with radii R _K , R _G , and R _A with the point O as the center. Since the electron beam radiates from the cathode (filament) 1 as shown in the figure, the length of the spot formed on the irradiation surface by the beam is larger than that of the conventional one. Here, there is a relationship of R _K ≤R _G <R _A between the radii R _K , R _G , and R _A of each electrode.

FIG. 3 is a schematic view of a large output deflection LFG according to the present invention,
(A) is a front view and (b) is a side view. The electron beam Bi emitted from the filament (cathode) 1 is transmitted to the grid 4,
After passing through the anode 6, it is exposed to the metal 8 in the crucible 9 undergoing a large deflection of 270 °, as shown in the figure, due to the force present on the left-hand side of Fleming by the existing magnetic field B. The irradiation point of the metal 8 is heated and melted to generate metal vapor.

By the way, the radial spread angle of the electron beam emitted from the filament is determined by the filament 1, the grid 4 and the anode 6.
And the length of the linear spot on the electron beam irradiation surface changes according to the radial spread angle of the electron beam. Therefore, the degree of this curvature may be determined according to the required spot length. In the case of the present invention, the length of the spot is
It is also proportional to the length of the electron beam passage path,
The longer this path is, the longer it will be. For example, filament 1
When the strength of the magnetic field in the same direction as the longitudinal direction is weakened or the voltage between the filament 1 and the anode 6 is increased, this path becomes longer, and the spot on the electron beam irradiation surface becomes longer.

Further, in the above-described embodiment, the filament 1, the grid 4 and the anode 6 are curved in a convex shape toward the emission direction of the electron beam, and the case where they are arranged concentrically is taken as an example. However, the present invention is not limited to this, and may be an arbitrary curved surface group or polygonal structure arranged in parallel with each other. Fourth
The figure shows another configuration example of the electrode system, (a) shows a curved surface which is not a concentric circle, and (b) shows a polygonal case. In the figure, A is an anode, G is a grid, and K is a cathode.

In the above-mentioned embodiment, the application example of the direct heating type electron gun by the direct current heating is explained, but it is also applicable to the direct heating type electron gun by the alternating current heating and the side heating type electron gun such as the electron impact type. Is.

(Effects of the Invention) As described in detail above, according to the present invention, since the filament, the grid and the anode are curved in a convex shape toward the emission direction of the electron beam, the electron beam is emitted substantially radially from the filament. Since the electron beam is spread out, it is possible to realize an electron gun in which a long linear spot is formed on the electron beam irradiation surface without using an electron optical lens.

[Brief description of drawings]

FIG. 1 is a mechanical configuration diagram showing an embodiment of the present invention, FIG. 2 is a diagram schematically showing the arrangement of an electrode system, and FIG. 3 is a schematic diagram of a large output deflection LFG according to the present invention. FIG. 4 is a diagram showing another configuration example of the electrode system, FIG. 5 is a diagram showing a configuration example of a conventional device,
FIG. 6 is an explanatory diagram of the deflection angle of the electron beam, and FIG. 7 is a diagram showing the emission state of the electron beam. DESCRIPTION OF SYMBOLS 1 ... Filament, 4 ... Beam shaping electrode (grid) 6 ... Beam acceleration electrode (anode), 8 ... Electrode 9 ... Crucible

Claims (1)

[Claims] 1. An electron gun having a linear filament, a grid and an anode arranged in parallel with the filament, wherein the filament, the grid and the anode are curved in a convex shape in a direction of emitting an electron beam. The electron beam is configured to be emitted substantially radially, and the electron beam emitted from the filament is deflected by a magnetic field in a direction substantially the same as the longitudinal direction of the filament to form a linear spot on the irradiation surface of the electron beam. An electron gun characterized by doing.