JPS61114449A - Electron gun - Google Patents

Abstract

PURPOSE:To achieve homogeneous intensity of the electron beam irradiated upon the target surface by causing the electron beam hole of the Wehnelt of an electron gun for electron beam annealing to have a rectangular shape having expanded areas corresponding to the longitudinal ends of the rectangular electron-emitting area of the cathode. CONSTITUTION:An electron gun for electron beam annealing consists of a U- shape cathode 1 made of tungsten wire, an anode 4 and a Wehnelt 3' having an electron ray hole 3H' which has an almost rectangular shape similar to the shape of the electron-emitting surface of the cathode 1 and having expanded ends. Annealing is performed by producing an electron beam with a homogeneous distribution along the longitudinal direction and then irradiating the electron rays upon the target. As a result, the intensity of the electron beam becomes greater in the longitudinal edges of the cross section of the electron beam than in the other area. Consequently, the influence of the escaping of heat from the peripheral area of the target is compensated, thereby performing homogeneous annealing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron gun for electron beam annealing suitable for performing uniform 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. The most important thing is to convert polycrystalline materials into single crystals. Recently, electron beam annealing has been attracting attention as the most effective technique for increasing the crystal grain size and forming single crystals. The electron beam annealing is generally performed by focusing an electron beam on, for example, polycrystalline silicon and simultaneously scanning the silicon. Now, if an electron beam with a spot-like cross-section is used in such electron annealing, the efficiency of annealing will be extremely poor, so a rectangular cross-section with a nearly line-like cross-section is used. There is.

FIG. 4(a) shows an electron gun that generates an electron beam with a linear rectangular cross-sectional shape. In the figure, reference numeral 1 denotes a cathode, which is made of, for example, a tungsten wire formed into a U-shape, and both ends of which are attached to terminal electrodes 2a and 2b. 3 is a Wehnelt, as shown in FIG. 4(b), a substantially rectangular electron beam passage 03 corresponding to the shape of the electron emitting surface of the cathode.
The sun is open. 4 is an anode. In such an electron gun, when a current is passed through the electrode, electrons are generated from the electron emitting surface of the cathode 1. At this time, when a negative DC bias voltage is applied between the cathode and Wehnelt 3, and a negative DC high voltage is applied between the cathode and the anode 4, the electron emission surface is shown in FIG. As such, electron beams are generated with a uniform distribution along the longitudinal direction, and the generated electron beams are directed toward a target (not shown).

[Problems to be Solved by the Invention] Now, when an electron beam with a rectangular cross section generated from such an electron gun is irradiated onto, for example, polycrystalline silicon, the part that has actually been 7-annealed is exposed to the electron beam. Narrower than the irradiated area.

The present invention aims to solve such problems and provides a novel electron gun.

[Means for Solving the Problems] The present invention provides an electron gun having a rectangular electron emitting section, in which a portion facing a longitudinal end portion of the rectangular electron emitting portion is wider than other portions. It is equipped with a Wehnelt having a passage section.

[Operation] When we considered the problems of annealing using the conventional electron gun, we found the following. When a rectangular electron beam hits a target, a small amount of heat escapes from the periphery of the rectangular cross section to other parts of the target due to thermal conduction. In particular, there is a lot of escape from the etched portion in the longitudinal direction of the rectangular shape. Therefore, the temperature of the periphery of the electron beam hitting the target, especially the etched part in the longitudinal direction, is lower than other parts, and the target in that part is not heated sufficiently. For this reason, if the target is polycrystalline, that portion is not sufficiently annealed.

Therefore, if the target is irradiated with an electron beam such that the electron beam intensity in the longitudinal direction of the electron beam cross section is greater than in other parts, the electron beam can be oriented in the longitudinal direction, and this problem can be solved. As a solution to this problem, if the portion of the Wehnelt electron beam passage opening facing the longitudinal end portion of the rectangular electron emitting portion is appropriately widened, the lines of electric force that enter this end portion will increase by the width. Therefore, the sixth electron from the electron gun
An electron beam having an electron beam intensity distribution as shown in the figure is obtained on the target.

[Embodiment] FIG. 1(a) shows an electron gun showing an embodiment of the present invention.
The electron beam passage port 3H" of the Wehnelt 3- of the electron gun is the first
As shown in Figure (b), the portion facing the end portion in the longitudinal direction of the rectangular powered electron beam emitting portion 1G is appropriately widened. This spreading method can be appropriately determined through experiments while observing the electron beam intensity distribution obtained at the target.

In particular, the spread of Wehnelt's etched area is adjusted so that the electron beam intensity distribution is such that the temperature of the target area due to the etched area in the longitudinal direction of the electron beam with a rectangular cross section is the same as the temperature of the target area due to other parts of the electron beam. It can be decided. .

FIG. 3 is a schematic diagram of an electron annealing apparatus using such an electron gun, in which 5 is a focusing lens, 6 is a deflector, and 7 is polycrystalline silicon. In such a device, an electron beam generated from an electron gun and having a rectangular cross section with an electron beam intensity distribution as shown in FIG.
focused on the top.

At the same time, the electron beam is scanned over the polycrystalline silicon 7 by the deflector 6, so that the portion of the silicon scanned by the electron beam is annealed.

In the above embodiment, the etched portion of the electron beam passage hole of the Wehnelt was made wide as appropriate, but as shown in FIG. The electron beam may be allowed to pass therethrough, and the shape between the two portions may be appropriately opened at the etched portion.

[Effect] If the electron gun of the present invention is used in an electron annealing device,
The current density at the end of the electron beam cross section can be increased, thereby supplementing the heat dissipation at the end of the line-shaped electron beam irradiation part, so that the electron beam irradiation part on the target is sufficiently annealed.

[Brief explanation of the drawing]

FIG. 1(a) is an electron gun showing one embodiment of the present invention, FIG. 1(b) is a Wehnelt embodiment of the electron gun, and FIG. 2 is a Wehnelt and other electron gun of the present invention. 3 is a schematic diagram of an electron annealing device, FIG. 4(a) is a schematic diagram of a conventional electron gun, FIG. 4(b) is a Wehnelt schematic diagram of the electron gun, and FIG. 5 is a schematic diagram of an electron annealing apparatus. 6 is an electron beam intensity distribution diagram obtained by a conventional electron gun, and FIG. 6 is an electron beam intensity distribution diagram obtained by an electron gun according to the present invention. 1: Cathode 3': Wehnelt 4 near node

Claims (1)

[Claims] An electron gun having a rectangular electron emitting part, characterized in that a Wehnelt is provided having a passing part in which a part opposite to a longitudinal end part of the rectangular electron emitting part is wider than other parts. gun.