JPH01206547A - Ion source with microwave heating type evaporating furnace - Google Patents

Abstract

PURPOSE:To facilitate the replacement and supply of a solid sample and make the maximum usage temperature about 1000 deg.C by using microwaves to heat the sample in an ion extraction type ion source heating the solid sample and evaporating and guiding it into a discharge chamber as the gas for plasma. CONSTITUTION:Microwaves generated by a microwave generating device 1 are guided into a plasma chamber 6 provided in a discharge electrode 5 via a branch wave guide 2, a microwave power regulator 3a, and a microwave guiding flange 4a to generate the microwave electric field. On the other hand, microwaves are fed to a solid sample evaporating furnace 9 through the branch wave guide 2, a microwave power regulator 3b, a microwave guiding flange 4b, and a evaporating furnace heating wave guide 8, the electric field generated in the plasma chamber 6 is applied to the sample gas evaporated from the solid sample. The electric power can be transmitted if only the wave guide is provided, and this device is completed only by putting the solid sample evaporating furnace absorbing microwaves in it.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an ion source used in an ion implantation device and an ion processing machine for thin film formation, surface modification, etc.
The present invention relates to an ion source having a function suitable for stably extracting ions from a sample having a vapor pressure of about 10'' Torr at a temperature of 0° C. for a long period of time.

[Conventional technology]

A sample heating furnace for a conventional ion source is disclosed in Japanese Patent Application Laid-Open No. 56-1327.
As described in Example 1 of Publication No. 54, a tungsten heater or a sheath heater was wound around the furnace.

[Problem to be solved by the invention]

In the above-described conventional technology, the tungsten heater is easily broken, making it difficult to handle when replacing samples or cleaning the furnace. On the other hand, in the case of a sheath heater, there were problems such as a low maximum operating temperature of around 500°C.

An object of the present invention is to realize an ion source that is easy to handle during sample exchange and furnace cleaning, and has an evaporation furnace with a high maximum operating temperature.

[Means to solve the problem]

The above problems are more or less unavoidable as long as a tungsten heater or sheath heater is used. Therefore, in order to achieve the above objectives.

A heating method that does not use a heater is needed. Specifically, this is achieved by using microwaves for heating.

[Effect]

Carbon-based materials, which are generally used as constituent materials for evaporation furnaces, are material islands that efficiently absorb microwaves. Therefore, with a simple configuration of placing an evaporation furnace made of carbon-based material inside a rectangular waveguide or coaxial line, it is possible to efficiently heat only the evaporation furnace. Then, the temperature of the evaporation furnace is controlled by the power of the introduced microwave.

In the case of the above configuration, the carbon evaporation furnace can be installed at any position within the waveguide, so there is a large degree of freedom in the structure, making it possible to create an evaporation furnace with good operability during sample exchange and furnace interior cleaning. .

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In this example, microwaves are also used to generate plasma, and the single ion source is configured so that one microwave generator is used to both heat the sample evaporation furnace and generate plasma. Wave generator 11 Branch waveguide 2. Microwave power regulators 3a, 3b, microwave introduction flange 4a
, 4b.

Discharge electrode 5. Plasma chamber 6. Gas sample introduction tube 7° Evaporation furnace heating waveguide 8. Solid sample evaporation furnace9. Ion beam extraction electrode system 10. It is composed of an a-field generator 11.

In the figure, microwaves generated by a microwave generator 1 are transmitted through a branch waveguide 2. A microwave electric field is generated in the plasma chamber 6 installed in the discharge electrode 5 via the microwave power regulator 3a and the microwave introduction flange 4a. On the other hand, for the solid sample evaporation furnace 9, the branch waveguide 2
．． Microwave power regulator 3b, microwave introduction flange 4b.

Microwaves are supplied through a waveguide 8 for heating the evaporation furnace. In the case of this embodiment, all the three-dimensional microwave circuits use rectangular waveguides, and the branching waveguide 2 has a characteristic of branching an equal amount of incident microwaves to both sides. Further, a flap type variable attenuator is used for the microwave power adjusters 3a and 3b. Therefore, the microwave generator 1 only has the function of always generating constant microwaves. With the microwave electric field generated in the plasma chamber 6, a magnetic field is applied near the plasma chamber 6 by the magnetic field generator 11 in a direction perpendicular to the microwave electric field, and then the gas sample introduction tube 7 or the solid sample evaporation furnace is By introducing the gaseous sample from 9, plasma of the introduced gas can be generated in the plasma chamber 6. Then, the ion beam 21 is extracted from the plasma by the ion beam extraction electrode system 10.

FIG. 2 is a diagram showing details of the solid sample evaporation furnace 9 and the plasma chamber 6. Inside the waveguide 8 for heating the evaporation furnace, dielectric insulators 12a, 12b, 12 are provided for the purpose of reducing the size of the waveguide and for holding the solid sample evaporation furnace 9.
Q is inserted.

The solid sample evaporation furnace 9 is made of carbon and includes a furnace body 9a and a holding lid 9.
The furnace body 9a has an introduction hole for guiding the evaporated sample to the plasma chamber 6. The microwave incident side (in this embodiment, the end of the presser cover 9b) is formed into a conical shape to reduce reflection of the microwave at this portion. To replace or replenish the solid sample, remove the tip insertion plate 8b of the waveguide 8 for heating the evaporation furnace.
This is done by removing the dielectric insulator 12b and the presser cover 9b.

A sheath type thermocouple 13 is used to measure the temperature of the solid sample evaporation furnace 9 to prevent the temperature measurement from being influenced by microwaves. The temperature of the solid sample evaporation furnace 9 is controlled by feeding back the output of the thermocouple 13 to the microwave power attenuator. The microwave power required to heat the solid sample evaporation furnace 9 to 1000° C. varies depending on the installation situation of the furnace, but it can be estimated to be at most 300 W even in a furnace that can secure an internal volume of 10 cm 3 .

On the other hand, the microwave power required to generate plasma is on the order of several hundred W, and this embodiment can exhibit sufficient performance by using the microwave generator 1 with an output of about 1 kW.

As described above, according to this embodiment, plasma generation and solid sample evaporation can be performed simultaneously with one microwave generator.
The heater power supply for heating the solid sample evaporation furnace, which was previously required, can be eliminated. Furthermore, since the microwave power input to the plasma and solid sample evaporation furnace is adjusted by a variable attenuator, there is no need to vary the output of the microwave generator, and the power source can be simplified.

In this example, a waveguide with a rectangular cross section was used as the waveguide for heating the evaporation furnace, but it is clear that the same effect can be obtained by using other waveguides such as a circular waveguide. be.

Furthermore, it is clear that even if a method other than microwave discharge is used to generate plasma, the effect of heating the solid sample evaporation furnace using microwaves, which will be explained in the next section, can be obtained.

In addition, although this example targeted only solid samples with low vapor pressure at room temperature, it is not necessary that the sample be solid, and it is clear that the same effect can be obtained for liquid samples as well.

〔Effect of the invention〕

According to the present invention, power can be transmitted as long as there is a waveguide, and the device can be completed by simply placing a solid sample evaporation furnace made of a material that absorbs microwaves well and can withstand high temperatures inside the waveguide. Therefore, it is possible to solve the problems peculiar to conventional solid sample evaporation furnaces that heat by wrapping a heater at once, and to realize an ion source with a furnace that allows easy replacement and replenishment of solid samples and a maximum operating temperature of about 1000 degrees Celsius. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIG. 2 is a detailed view of the portion 1 in FIG. 1... Microwave generator, 2... Branch waveguide, 3a
. 3b...Microwave power regulator, 4a, 4b...
Microwave introduction flange, 5...discharge electrode, 6...
Plasma chamber, 7... Gas sample introduction tube, 8 (8a, 8
b)...Evaporation furnace heating waveguide, 9 (9a, 9b).
...Solid sample evaporation furnace, 10...Ion beam extraction electrode system, 11-...Magnetic field generator, 12a, 12b, 12c
... m electric insulator, 13 ... thermocouple, 21 ... ion beam. Fig. 1 Y Z Fig. 6 Alaskan Den 3b Answer All Wide Private Doinou Tube J Cane Class No. 26/Zb Wrong 4i Fat Ipak R Sniff Enjashio/3 4 View 1C Zusu

Claims (1)

[Claims] 1. In an ion source that heats and evaporates a solid sample, introduces it into a discharge chamber as a plasma gas, and extracts ions from the plasma, the solid sample is heated by microwaves. An ion source with a microwave heating evaporation furnace. 2. The ion source with a microwave heating evaporation furnace according to claim 1, wherein microwaves are also used to generate plasma. 3. The ion source according to claim 2, characterized in that plasma generation and heating of the solid sample are performed using microwaves generated by one microwave generator. ion source.