JPH0955169A - Sample evaporation source for ion source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably hold a necessary vapor pressure, even in the case of a molten sample having large wettability. SOLUTION: A sample container 20 in which a solid sample is filled at the normal temperature is insulated and fitted to a flange board 3 and a vapor emission part of the container is formed from a porous body 20a of a high melting point material. When the sample container is heated by a heater 8 and the sample is melt, a sample of large wettability is impregnated in the outer surface of the porous body and evaporated from the surface, and the vapor is supplied in a plasma generation chamber 1. The molten sample is not crept from the sample container. When a prescribed electric potential is applied on the sample container in relation to a plasma generation chamber by a bias DC supply source 23, electrons or ions in plasma collide with the molten sample impregnated in the sample container or the porous body so as to be heated. Heating by the heater 8 and heating by the electropotential adjustment of the sample container facilitate the temperature control of the sample container including the porous body part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample evaporation source for supplying a solid sample at room temperature to an ion source such as an ion implantation apparatus by vapor.

[0002]

2. Description of the Related Art Conventionally, when a solid substance at room temperature is used as a sample for an ion source, the sample is filled in a crucible of an oven and heated to melt (liquefy) and evaporate the sample into an ion source. We are supplying. FIG. 4 is a schematic cross-sectional configuration diagram of an example of a bucket type ion source, and FIG. 5 is an enlarged perspective view showing a sample evaporation source in the same ion source with a part cut away. The sample evaporation source 2 is attached to the lower part of the plasma generation chamber 1 of the ion source. The sample evaporation source 2 is assembled to the flange plate 3, and the sample evaporation source is attached to the ion source by connecting the flange evaporation plate 2 to the flange 5 of the evaporation source port 4 formed in the plasma generation chamber 1.

The crucible 6 filled with the sample in the sample evaporation source 2 is housed in an oven 7 for uniformly heating the sample. A heater 8 for heating is provided around the oven 7.
Is further provided, and the surroundings are covered with a heat shield plate 9 to uniformly heat and melt and evaporate the sample 10 in the crucible, and the sample vapor is supplied into the plasma generation chamber 1 through the opening of the crucible.

Electrons from the thermionic emission filament 11 hit the vapor of the sample supplied into the plasma generation chamber 1 to generate plasma, and the beam extraction electrode system of the plasma electrode 12, the extraction electrode 13, and the ground electrode 14 is used. The ion beam is extracted. Plasma generation chamber 1
Is provided with a heater 15 and a heat shield plate 16 for keeping the inside of the chamber at a predetermined temperature, and a magnet 17 for forming a magnetic field for plasma confinement is attached to the outer wall of the chamber. There is.

[0005]

When the sample 10 is melted (liquefied), it is compatible with the crucible 6 and aluminum,
When the wettability of a metal sample is large like silicon, the molten sample crawls up the crucible, wraps around the outside of the crucible, and further enters the oven 7. May adhere to even. In this case, even if the crucible heating heater is appropriately heated, the required sample vapor pressure necessary for plasma generation cannot be generated or the vapor pressure becomes unstable, and the sample evaporation source 2 is set to the ion vaporization source. When removed from the source, a situation occurs where the evaporation source components are damaged, including the inability to remove the crucible 6 from the oven 7.

The present invention prevents the melted sample from crawling even when the wettability of the melted sample is particularly high, can stably maintain the required vapor pressure, and prevent damage to the constituent members. The purpose is to provide a sample evaporation source for an ion source.

[0007]

An evaporation source for an ion source according to the present invention is provided with a sample container in which a sample is filled and a sample vapor discharge part is formed of a porous body, and around the sample container. Its main feature is that it comprises a heater for heating.

By heating the sample container with a heater for melting and melting the sample inside, the molten sample having high wettability is impregnated into the outer surface of the porous body and evaporated from the surface.
The vapor is supplied into the plasma generation chamber of the ion source.

Further, according to the present invention, the sample container is attached so as to be insulated from the plasma generation chamber of the ion source, and the sample container can be provided with a required electric potential for the plasma generation chamber. It is characterized by that.

By applying a required electric potential to the plasma generation chamber in the sample container, electrons or ions in the plasma generated in the plasma generation chamber are made to collide with the sample container and the molten sample impregnated in the porous body. Can be heated. By applying not only the heating by the heater for heating but also the heating control by adjusting the potential of the sample container, it becomes easy to control the temperature of the sample container including the porous body part, and the vapor required for plasma generation in the plasma generation chamber. The required temperature for supplying a fixed amount of steam so that the pressure is stably maintained can be stably maintained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A sample container in which a solid sample is filled at room temperature is made of a high melting point material, and a vapor discharge part of the container is made of a porous body made of a high melting point material. This porous body is formed by sintering a powder of a refractory metal material such as tungsten, tantalum, molybdenum, or a refractory material such as carbon or silicon carbide, heating the powder, and adhering the powder surfaces. When a heater for heating is installed around the sample container and the sample is melted and the sample is melted, the molten sample with high wettability is impregnated to the outer surface of the porous body, and the molten sample does not crawl from the surface. , Evaporate from the surface.

The porous body in the vapor discharge part of the sample container can be formed by providing the vapor discharge part with a large number of pores for impregnating and evaporating the molten sample, and
It is possible to form one mesh or a proper number of meshes having a fine mesh so that the molten sample is impregnated and evaporated so as to evaporate.

A sample container in which the vapor discharge part is made of a high melting point material is attached to the plasma generation chamber of the ion source in an insulated manner, and a bias DC power supply is connected between the sample container and the plasma generation chamber. With this power supply, the sample container is given a required electric potential for the plasma generation chamber, and electrons or ions in the plasma generated in the plasma generation chamber are made to collide with the sample container and the molten sample impregnated in the porous body and heated. To do. The combined use of heating by the heater and heating by adjusting the potential of the sample container facilitates temperature control of the sample container including the porous body portion.

[0014]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional configuration diagram of the embodiment, and the same reference numerals as those in FIGS. 4 and 5 denote the same parts. The ion source sample evaporation source 2 is assembled on the flange plate 3 and attached to the evaporation source port 4 at the upper part of the plasma generation chamber 1. A sample container 20 filled with a solid sample at room temperature is insulated and attached to the flange plate 3 using a support member 21 and an insulator 22, and the vapor discharge part of the container is a porous body 20a made of a high melting point material. Is formed by.

A heater 8 for heating is provided around the sample container 20. For a sample having a high melting point, a heat shield plate 9 is provided outside the heater 8 for heating so that the sample container can be kept at a high temperature. To provide. By heating the sample container 20 and melting the sample inside, the molten sample 10 having high wettability is impregnated even into the outer surface of the porous body 20a, and the sample is evaporated from the surface of the porous body having a certain area to form a vapor. Are supplied into the plasma generation chamber 1. Sample container 2 by heater 8
By adjusting the temperature to 0, the molten sample does not crawl from the porous body 20a, and the steam capable of maintaining the vapor pressure necessary for plasma generation can be stably supplied into the plasma generation chamber 1.

A bias DC power supply 23 is connected between the sample container 20 and the plasma generation chamber 1 via a support member 21 of the sample container 20, and a potential is applied to the sample container including the porous body 20a with respect to the plasma generation chamber. Try to give.
For example, when a positive potential is applied to the sample container 20 with respect to the plasma generation chamber 1, electrons in the plasma generated in the chamber collide with the porous body 20a and the molten sample impregnated in the porous body. , Heat. Also, the sample container 2
By applying a negative potential to the plasma generation chamber 1 at 0, ions can be made to collide with the sample container and the molten sample to heat them. By applying not only the heating by the heating heater 8 but also the heating control by adjusting the potential of the sample container 20, it becomes easy to control the temperature of the sample container including the porous body portion and generate plasma in the plasma generation chamber 1. It is possible to stably obtain the required temperature for supplying a fixed amount of vapor that can stably maintain the required vapor pressure.

The sample container 20 is made of a high melting point material, and the porous body 20a has a high melting point material such as a high melting point metal material such as tungsten, tantalum, molybdenum, or a high melting point material such as carbon or silicon carbide. Formed by sintering the powder of the material, heating the powder and sticking the powder surfaces together. The size of the powder particles of the high melting point material is selected so that the formed porous body 20a is impregnated with the molten material and the evaporation from the surface is appropriate.

The vapor discharge portion of the sample container 20 is the porous body 20.
a is formed by impregnating a porous sample with a molten sample,
Since the sample container is evaporated from the surface, it is possible to arrange the sample container at an arbitrary angle position above the horizontal side surface portion of the plasma generation chamber 1, but as shown in FIG.
It is best to mount vertically and downward on the top of the. In this case, even if the molten sample in the sample container 20 decreases, the porous sample 20a in the vapor discharge portion is always impregnated with the molten sample, and the sample vapor is always stably supplied regardless of the amount of the sample in the container. be able to.

FIG. 2 is a sectional view showing the structure of another embodiment, and the same reference numerals as those in FIG. 1 denote the same parts. The porous body 20a forming the vapor discharge part of the sample container 20 is provided up to the side surface of the container. The sample container 20 is attached to the flange plate 3 without insulation, and the flange plate is an insulator 2.
2'is interposed so as to be insulated and attached to the plasma generation chamber 1 so that a potential can be applied to the sample container in the chamber. The porous body 20a may be provided on the entire surface of the sample container 20, the side surface, or a part thereof. Since the molten sample is impregnated in the porous body 20a and evaporated from the surface, the molten sample does not get wet from the porous body and adhere to surrounding members.

FIG. 3 shows another embodiment of the essential part of the present invention, the sample container. In FIG. 3A, a large number of pores 24 are formed in the vapor discharge part of the sample container 20 formed of a high melting point material.
Is provided. The molten sample is impregnated into the pores from the inside of the container and evaporated, and the sample vapor is supplied into the plasma generation chamber of the ion source.

In FIG. 3B, a fine mesh 25 is attached to the vapor discharge portion of the sample container 20 formed of a high melting point material. By laminating one mesh or an appropriate number of meshes, the molten sample is impregnated into the mesh from the inside of the container and evaporated, and the sample vapor is supplied into the plasma generation chamber of the ion source.

The portion where the pores 24 are formed in the sample container 20 and the mesh 25 attached to the sample container 20 are included in the porous body referred to in the present specification.

The sample evaporation source for an ion source of the present invention can be applied to any ion source capable of generating ions by supplying a sample with vapor (gas), and is not limited to a bucket type ion source, but an ECR ion source. , A Freeman ion source, a Kauffman ion source, etc.

[0024]

Since the present invention is configured as described above, by heating the sample container and melting the sample inside, the molten sample having high wettability is impregnated to the outer surface of the porous body. Since the vapor can be evaporated from a certain area on the surface, the vapor can be stably supplied to the plasma generation chamber of the ion source, and the molten sample does not crawl out, so that the vapor source constituent members are not damaged.

By applying a required electric potential to the plasma generation chamber to the sample container, electrons or ions in the plasma generated in the plasma generation chamber are heated by colliding the ions with the sample container and the molten sample. Therefore, not only the heating by the heater for heating but also the heating control by the potential control of the sample container facilitates the temperature control of the sample container including the porous body part, and the plasma generation in the plasma generation chamber. It is possible to stably maintain a predetermined temperature for supplying a constant amount of vapor so that the required vapor pressure is stably maintained.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram of an embodiment of the present invention.

FIG. 2 is a sectional configuration diagram of another embodiment.

FIG. 3 is a configuration diagram of another specific example of a main part of the present invention and a sample container.

FIG. 4 is a schematic cross-sectional configuration diagram of a bucket type ion source having a conventional sample evaporation source.

5 is an enlarged perspective view showing the sample evaporation source in FIG. 4 with a part thereof cut away.

[Explanation of symbols]

 1 Plasma Generation Chamber 2 Sample Evaporation Source 3 Flange Plate 4 Evaporation Source Port 8 Heating Heater 9 Heat Shielding Plate 20 Sample Container 20a Porous Body 21 Support Member 22, 22 'Insulator 23 Bias DC Power Supply 24 Pore 25 Mesh

Claims (2)

[Claims] 1. An ion comprising a sample container filled with a sample and having a sample vapor discharge portion formed of a porous body, and a heating heater provided around the sample container. Sample evaporation source. 2. The sample container is attached so as to be insulated from the plasma generation chamber of the ion source, and the sample container is configured so that a required electric potential can be applied to the plasma generation chamber. The sample evaporation source for an ion source according to claim 1.