JPH0212376B2 - - Google Patents

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] In order to realize high-speed, high-density or multi-functional three-dimensional circuit elements by stacking elements, it is necessary to change the crystal grain size of polycrystalline materials (e.g. polycrystalline silicon) deposited on a green film. Most emphasis is placed on increasing or single crystallizing polycrystalline materials. 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 the annealing will be extremely poor, so a rectangular cross-section with a nearly line-like cross-section is used. There is.

FIG. 4a shows an electron gun that generates an electron beam with a linear rectangular cross section. 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, and as shown in FIG. 4b, a substantially rectangular electron beam passage opening 3H is opened in accordance with the shape of the electron emitting surface of the cathode. 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 is actually annealed will be irradiated with the electron beam. narrower than the part that was

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. A wehnelt having a passage section is provided.

[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 edges of the rectangular shape in the longitudinal direction. Therefore, the temperature of the periphery of the electron beam hitting the target, especially the edge in the longitudinal direction, is lower than other parts, and the target in that part is not sufficiently heated. For this reason,
If the target is polycrystalline, that portion will not be sufficiently annealed.

Therefore, if the electron beam is applied to the target so that the electron beam intensity at the longitudinal edge part of the electron beam cross section is higher than the other parts, even if heat escapes from the longitudinal edge part, Since this amount is compensated for, this kind of problem is solved. As a solution to this problem, if the Wehnelt electron beam passage opening facing the longitudinal end of the rectangular electron-emitting part is widened appropriately, the lines of electric force that enter this end will increase by the width. , the sixth 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. 1a shows an electron gun showing an embodiment of the present invention, in which the electron beam passage port 3 of the Wehnelt 3' of the electron gun
As shown in FIG. 1b, H' is appropriately widened at a portion facing the longitudinal end portion of the rectangular cathode electron beam emitting portion 1G. This spreading method can be appropriately determined through experiments while observing the electron beam intensity distribution obtained at the target. In particular, the width of the Wehnelt edges is such that the electron beam intensity distribution is such that the temperature of the target portion due to the longitudinal edge portion of the electron beam with a rectangular cross section is the same as the temperature of the target portion due to other portions 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 an apparatus, an electron beam generated from an electron gun and having a rectangular cross section with an electron beam intensity distribution as shown in FIG. 6 is focused onto polycrystalline silicon 7 by a focusing lens 5. 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 edge portion of the electron beam passage opening of the Wehnelt was widened appropriately, but as shown in FIG. 2, the Wehnelt is composed of two parts 3a and 3b, and a The electron beam may be allowed to pass therethrough, and the shape between the two portions may be appropriately opened at the edges.

[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 making it possible to compensate for the heat dissipation at the end of the line-shaped electron beam irradiation section. Therefore, the portion of the target that is irradiated with the electron beam is sufficiently annealed.

[Brief explanation of drawings]

FIG. 1a shows an electron gun showing an embodiment of the present invention;
FIG. 1b is a diagram of one embodiment of the electron gun,
FIG. 2 is a diagram of Wehnelt's other embodiment of the electron gun of the present invention, FIG. 3 is a schematic diagram of an electron annealing device, and FIG.
Figure a is a schematic diagram of a conventional electron gun, Figure 4b is a Wehnelt schematic diagram of the electron gun, Figure 5 is an electron beam intensity distribution diagram of the conventional electron gun, and Figure 6 is an electron beam intensity distribution diagram of the electron gun of the present invention. It is a line intensity distribution map. 1: cathode, 3': Wehnelt, 4: anode.

Claims (1)

[Claims] 1. An electron gun having a rectangular electron emitting section, characterized in that a Wehnelt is provided having a passing section in which a portion opposite to a longitudinal end portion of the rectangular electron emitting section is wider than other portions. electron gun.