JPS62198033A - Liquid metallic ion source - Google Patents

Abstract

PURPOSE:To realize a long service life and a high property, by burying a mesh- form filament to which a current is applied for heating, inside the wall of a crucible. CONSTITUTION:A mesh-form filament 5 to which a current is applied for heating is coated with an alumina material 6 to form a crucible 3. At the center hole of the crucible 3, a needle-form chip 1, made of or coated with a reaction- resisting substance, is inserted, and the needle-form chip 1 is held by a crucible lid 4. Since the unnecessary evaporation of the ionized metal 2 is prevented by the crucible lid 4, the service life of the ion source is long.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to improvement of a liquid metal ion source, and particularly to an electrically heated liquid metal ion source with longer life and higher performance by improving a crucible for storing ionized metal. .

[Prior Art] Liquid metal ion sources are particularly useful in focused ion beam devices and the like. Conventionally, various liquid metal ion sources have been proposed. For example, Japanese Patent Application Laid-Open No. 58-198822 proposes a liquid metal ion source with improved longevity and performance. A cross-sectional view of a part of this electrically heated liquid metal ion source is shown in FIG. 2, and the crucible 3' has a two-layer structure having a 6° layer of a reaction-resistant material and a layer of carbon 7'. Inside the 3° heating filament 5° is covered with a reaction-resistant material 6′.

However, since this ion source uses a heating filament made of a single wire wound into a coil, there is a drawback that if the filament breaks, heating will no longer be possible. Furthermore, since the crucible has a structure in which the carbon material on the outer side covers the inner side in order to reinforce the inner side, the structure is complicated.

[Object of the Invention] An object of the present invention is to provide an ion source that does not have the above-mentioned drawbacks and has a long life and high performance.

[Structure of the Invention] The gist of the present invention is to provide a liquid having a crucible for storing ionized metal, a needle tip inserted into the center hole of the crucible and functioning as an ion beam emitter, and an extraction electrode for extracting the ion beam. A liquid metal ion source is characterized in that a mesh-like filament for electrical heating is embedded inside the wall of a crucible.

The crucible is a material with a high melting point, reaction resistance, and good wettability.
For example, it is preferably made of a ceramic material containing alumina. Preferably, the needle tip is made of a reactive material, for example a carbide such as TiC, VC, NbC, or has a reactive material coating. Moreover, it is preferable that the crucible has a lid.

The ion source of the present invention will be specifically described below with reference to the accompanying drawings. Note that the ion source of the present invention is not limited to the following embodiments.

FIG. 1 is a partial sectional view showing an integrated example of an electrically heated liquid metal ion source according to the present invention. As shown in the upper right corner of the drawing, a mesh-shaped electrical heating filament 5 is covered with an alumina material 6, forming a crucible 3. A leaf-shaped tip I made of or coated with a reaction-resistant material is inserted into the central hole of the crucible 3, and the needle-shaped tip 1 is supported by the crucible M4. The crucible M4 prevents unnecessary evaporation of the ionized metal 2, and the life of the ion source is long.

[Effects of the Invention] Since the electric heating filament has a mesh shape, heating is spread over the entire area of the crucible and heating efficiency is improved compared to conventional filaments. Furthermore, the crucible does not become incapable of heating even if the filament breaks in several places, and has sufficient strength, such as mechanical strength and thermal shock resistance and mechanical strength, even without reinforcement.

Ionized metals with high saturated vapor pressures can also be used if the crucible has a lid. It is particularly useful in the ionization of reactive ionized metals if the parts that contact the ionized metal, ie, the crucible and the needle tip, are reaction resistant.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an electrically heated liquid metal ion source of the present invention, and FIG. 2 is a partially sectional view of a conventional electrically heated liquid metal ion source. l... Needle tip, 2... Ionized metal, 3.3゛... Crucible, 4... Crucible lid, 5,5゛... Filament for electrical heating, 6.6°... Reactive substances, 7
゛... Carbo Figure 1 Figure 2

Claims (1)

[Claims] 1. A liquid metal ion source having a crucible for storing ionized metal, a needle tip inserted into the center hole of the crucible and functioning as an ion beam emitter, and an extraction electrode for extracting the ion beam. A liquid metal ion source characterized in that a mesh-shaped electrical heating filament is embedded inside the wall of a crucible. 2. The liquid metal ion source according to claim 1, wherein the crucible is made of a ceramic material containing an alumina material. 3. The liquid metal ion source according to claim 1, wherein the needle tip is made of a reactive material or coated with a reactive material. 4. The liquid metal ion source according to claim 1, wherein the crucible has a lid.