JPH0238365Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electron gun suitable for electron beam annealing.

[Prior art] Increasing the crystal grain size of polycrystalline materials (e.g., polycrystalline silicon) deposited on an insulating film to realize three-dimensional circuit elements with high speed, high density, or multifunction by stacking elements. Alternatively, the single crystallization of polycrystalline substances is considered most important. Recently, electron beam annealing has been attracting attention as the most effective technique for increasing the crystal grain size and forming single crystals. In the electron beam annealing, an electron beam is usually focused on, for example, polycrystalline silicon and simultaneously scanned over the polycrystalline silicon to perform annealing. If an electron beam with a spot-shaped cross section is used in such electron beam annealing, the efficiency of the annealing is extremely poor, so an electron beam with a rectangular cross-sectional shape that is nearly line-shaped is used.

Now, as shown in FIG. 3, an electron gun that generates such an electron beam generally has a W wire formed in a U-shape, and electrodes 2a and 2b having respective terminals connected to a heating wire 1. a cathode 3 connected to the cathode, and a Wehnelt 4 having an electron beam passage opening having a shape similar to the shape (line shape) of the electron emitting surface of the cathode;
An anode consisting of 5 is used.

[Problems that the invention aims to solve] However, in electron beam annealing, in order to obtain a line-shaped electron beam on the target, a distance of several hundred μm is required.
A cathode is formed by a W-line with a large diameter, but since the W-line has a large envoy function, a beam of sufficient brightness cannot be obtained from such a thin W-line cathode. Therefore, in order to obtain a beam of sufficient brightness, the current (several tens of amperes) that is normally applied during electron beam annealing is
If more current is supplied, the W line cathode will be quickly consumed. In addition, the beam intensity distribution in the width direction of the electron beam emission surface of the W-line cathode becomes a Gaussian distribution with poor uniformity, making it impossible to obtain a line-shaped beam with a predetermined beam intensity on the target, resulting in heating spots on the target. occurs. Furthermore, as mentioned above, in electron beam annealing, a current of several tens of amperes is normally passed through the cathode, so the magnetic field of the W-line cathode is strong enough to change the direction of the beam from the electron beam emitting surface of the cathode from the direction toward the target. (The force acting on the beam is due to Fleming's left hand rule).

The purpose of the present invention is to solve such problems.

[Means for solving the problem] The electron gun of the present invention has a cathode made of LaB ₆ single crystal whose electron emission surface is formed in a flat line shape, and is arranged on both sides of the cathode along the longitudinal direction of the cathode. a heating element, and means for supplying current to the heating element.

[Embodiment] FIGS. 1a and 1b are schematic diagrams of an electron gun for electron beam annealing showing an embodiment of the present invention. FIG. 1a is a sectional view taken from the direction of the electron emitting surface, and FIG. 1b is a sectional view taken from a direction perpendicular to the direction of the electron emitting surface. 5 in the figure is a single crystal with crystal direction 110
In LaB ₆ , there is a rectangular parallelepiped 5a with a length of 10 mm in the longitudinal direction, a length of 1 mm in the width direction, and a height of 1 mm, and a rectangular parallelepiped with a length of 10 mm in the longitudinal direction and a length in the width direction in the center of the rectangular parallelepiped in the width direction. The cathode is shaped like a stack of rectangular parallelepipeds 5b with a diameter of 0.2 mm and a height of 0.3 to 0.4 mm. Reference numeral 6 denotes heating elements (eg, pyrolithic graphite) arranged on both sides in the width direction of the rectangular parallelepiped 5a forming the cathode. Reference numeral 7 denotes a rectangular parallelepiped cup that accommodates the cathode 5 via the heating element 6, and is made of a heat-generating material, such as carbon. 8a,
8b is a tungsten wire, one end of which is an electrode 9a,
9b, and the other ends are connected to both side ends of the cup 7, respectively. A heating power source (not shown) is connected to the electrode.

Figure 2 shows an example of an electron beam annealing device equipped with such an electron gun EB.
0 targets the electron beam from the electron gun (e.g.
This is a focusing lens for focusing on the polycrystalline silicon (polycrystalline silicon) 11. 12 is a deflector for scanning the electron beam focused on the target.

First, a heating power source (not shown) is activated to supply current to the cup 7 through the electrodes 9a, 9b and the tungsten wires 8a, 8b. Then, a current flows from the cup 7 to the heating element 6 and the cathode 5, the cup and the heating element 6 generate heat, and the cathode 5 is heated to about 1500°C by the heat generation. Then, an electron beam is generated in the direction of the target 11 from the flat linear electron beam emitting portion of the rectangular parallelepiped portion 5b of the cathode. The electron beam is focused onto a target 11 by a focusing lens 10. The cross section of the electron beam on the target has a similar shape to the linear electron beam emitting section. Since the line-shaped electron beam is scanned over the target by the deflector 12, the target (eg, polycrystalline silicon) is annealed.

[Effects of the invention] In the electron gun of the invention, the cathode is formed of LaB ₆ , which has a significantly smaller work function than the W line.
Even if the electron emitting surface is formed into a line with a width of about 100 μm, a beam of sufficient brightness can be obtained with less than the current (several tens of amperes) (about 1/10 current) of normal electron beam annealing, and the level of cathode wear is small. It's also small. Further, since the electron beam emitting surface is formed in a flat line shape, the beam intensity distribution in the width direction is uniform, and a line-shaped beam with a predetermined beam intensity can be obtained on the target. Furthermore, although a current of several tens of amperes is normally passed through the cathode, as mentioned above, the current is only about 1/10 of that of a conventional W-line cathode, so it is possible to target the direction of the beam from the electron beam emitting surface of the cathode. A magnetic field is not generated around the cathode that is large enough to deviate from the direction of the cathode.

[Brief explanation of the drawing]

Figures 1a and b are schematic diagrams of the electron gun of the present invention;
The figure is a schematic diagram of an electron beam annealing apparatus showing an example of the use of the electron gun of the present invention, and FIG. 3 is a schematic diagram of a conventional electron gun. 5a, 5b... Rectangular parallelepiped portion forming the cathode, 6
... Heating element, 7... Cup, 8a, 8b... Tungsten wire, 9a, 9b... Electrode.

Claims (1)

[Scope of utility model registration request] The electron emitting surface is formed in a flat line shape.
An electron gun comprising a cathode made of LaB ₆ single crystal, heating elements arranged on both sides of the cathode along the longitudinal direction of the cathode, and means for supplying current to the heating elements.