JP3400228B2 - Thermal electron cleaning device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in various electro-optical instruments such as electron microscopes and surface analytical instruments, and various analytical instruments such as elemental / structural analytical instruments, and is disposed inside instruments such as samples and probes for cleaning. The present invention belongs to the technical field of a cleaning device for cleaning a member to be cleaned that requires the above, and more particularly to the technical field of a thermoelectron cleaning device adapted to clean a member to be cleaned by thermoelectrons.

[0002]

2. Description of the Related Art In various electro-optical instruments such as electron microscopes and surface analyzers or various analyzers such as elemental / structural analyzers, which have been developed in the past, members to be cleaned such as a sample and a probe are used. Is cleaned by the electron impact heating method. The electron impact heating method is a method of performing cleaning by colliding thermoelectrons generated by a filament with a member to be cleaned to heat the member to be cleaned.

FIG. 4 is a diagram schematically showing an ultra-high vacuum scanning tunneling microscope (UHV-STM) as a conventional device adopting such an electron impact heating method. In the figure, 1 is UHV-STM, 2 is an ultra high vacuum sample processing chamber, 3
Is a parking mechanism rotatably provided in the ultra-high vacuum sample processing chamber 2, 4 is a sample held by the parking member 3,
5 is a probe held by the parking member 3, 6 is an image observation chamber for observing the sample 4, 7 is an STM stage arranged in the image observation chamber 6 and on which the sample and the probe are mounted, 8 is The first for transporting the sample 4 and the probe 5 into the ultra-high vacuum sample processing chamber 2
A transport mechanism, 9 is a first core rod such as an iron core, 10 is a first gripping portion that is provided at the tip of the first core rod 9 and grips the sample 4, the probe 5, and the like, and 11 holds the first core rod 9. First magnet, 12
Is a first guide rail for guiding the first magnet 11, 1
3 is a second transport mechanism for transporting the sample 4 and the probe 5 into the image observation chamber 6, 14 is a second core rod such as an iron core, and 15 is a sample 4 and the probe provided at the tip of the second core rod 14. A second gripping portion for gripping 5 and the like, 16 a second magnet for holding the second core rod 14,
7 is a guide rail for guiding the second magnet 16, 18
Is a first connection passage that airtightly connects the ultra-high vacuum sample processing chamber 2 and the image observation chamber 6, and 19 is a first connection passage that opens and closes the first connection passage 18.
A gate valve, 20 is an exchange chamber for the sample 4 and the probe 5, 21
Is a second connection passage that airtightly connects the ultra-high vacuum sample processing chamber 2 and the exchange chamber 20, and 22 is a second connection passage that opens and closes the second connection passage 21.
It is a gate valve.

As shown in FIG. 4, in the UHV-STM1 thus constructed, when the sample 4 and the probe 5 are transferred to the ultrahigh vacuum sample processing chamber 2 and the image observation chamber 6, first of all, Also, the second gate valves 19 and 22 are closed to shut off the chambers 2, 6 and 20 from each other. Exchange room 20 in this state
Is set as the atmospheric pressure, and the sample 4 and the probe 5 are put in the exchange chamber 20 under this atmospheric pressure state to be held by the first holding unit 10. Next, the exchange chamber 20 is hermetically sealed from the atmosphere, and after the exchange chamber 20 is in a high vacuum state of a predetermined negative pressure, the second gate valve 22 is opened and the second connection passage 21 is opened. The ultrahigh vacuum sample processing chamber 2 and the exchange chamber 20 are communicated with each other. Next, the first magnet 11 of the first transfer mechanism 8 is moved along the guide rail 12 toward the ultra-high vacuum sample processing chamber 2 together with the first core rod 9 by a manual or power motor (not shown), and the first gripping is performed. The sample 4, the probe 5 and the like held by the section 10 are conveyed into the ultra-high vacuum sample processing chamber 2 and attached to the parking mechanism 3.

After that, the first magnet 11 and the first core rod 9
Then, the first grip portion 10 is returned to the original position shown in the drawing, the second gate valve 22 is closed, and the inside of the ultra-high vacuum sample processing chamber 2 is brought to the ultra-high vacuum state again. In this state, the sample 4, the probe 5 and the like are cleaned by the electron impact heating method in the ultra high vacuum sample processing chamber 2. Next, the first gate valve 19 is opened to open the first connection passage 18, and the ultrahigh vacuum sample processing chamber 2 and the image observation chamber 6 are connected to each other. Then, the second magnet 16 of the second transport mechanism 13 is moved along the guide rail 17 toward the parking mechanism 3 together with the second core rod 14 manually or by a power motor (not shown), and the second grip portion 15 is used to move the parking mechanism. Sample 4 attached to 3
Alternatively, the probe 5 is gripped. Further, the second magnet 16 is moved along the guide rail 17 toward the image observation chamber 6 to form the second core rod 1.
4, the second grip 15 and the sample 4 or the probe 5 gripped by the second grip 15, and the sample 4 or the probe 5 is conveyed into the image observation chamber 6 and the STM in the image observation chamber 6 is moved. The stage 7 is mounted at a predetermined position. After that, the sample 4 is observed by the UHV-STM1 in the image observation chamber 6.

FIG. 5 is a diagram for explaining cleaning in the ultra-high vacuum sample processing chamber 2 of the UHV-STM 1 by the electron impact heating method. In the figure, 23 is a filament for generating thermoelectrons e, 24 is a filament heating power source for heating the filament 23, 25 is a sample 4, a probe 5, etc. (in the figure, the sample 4 is representatively shown. In the following description, the sample 4 will be described, but other members to be cleaned such as the probe 5 are the same as in the case of the sample 4).

When the sample 4 is cleaned by the electron impact heating method, in the ultra-high vacuum sample processing chamber 2 as shown in FIG. 5, first, a current is applied to the filament 23 by the filament heating power source 24 to heat the filament 23. At the same time, a positive voltage (for example, several 100 to 1000 V) is applied to the sample 4 by the voltage applying power supply 25 via the parking mechanism 3.

When the filament 23 is heated, thermoelectrons e are generated from the filament 23, and the thermoelectrons e are pulled and accelerated by the positive voltage applied to the sample 4 and vigorously collide with the sample 4. To do. By heating the sample 4 by this electron impact, the sample 4 is cleaned. The cleaning by the electron impact heating method has an effect that a relatively easy deposit can be removed with a simple structure and a simple method.

[0009]

However, when a substance having a high melting point adheres to the surface of the sample 4 or a compound such as a carbide is formed on the surface of the sample 4, the conventional electron impact heating method completely removes these adhered substances. Can not be removed.

Therefore, in order to remove the deposits that cannot be completely removed by the electron impact heating method from the surface of the sample, conventionally, sputter cleaning of the sample 4 such as etching with an ion gun is performed. However, in sputter cleaning using an ion gun, not only the cleaning device becomes large, but also the cost becomes high.

The present invention has been made in view of the above circumstances, and an object thereof is to reliably remove deposits which cannot be completely removed by the electron impact heating method, and are small and inexpensive. It is to provide a cleaning device using thermoelectrons.

[0012]

In order to solve the above-mentioned problems, the invention of claim 1 is a gas introducing means for introducing a gas into the sample processing chamber, and the gas is introduced into the sample processing chamber and heated. A filament that generates thermoelectrons by
A heating power source for heating the filament, a parking mechanism disposed in the sample processing chamber, to which a member to be cleaned such as a sample or a probe is attached, and a first voltage applying negative voltage to the member to be cleaned. A voltage applying unit, a gas ionizing unit disposed in the sample processing chamber for accelerating the generated thermoelectrons to interact with the gas to ionize the gas, and a positive voltage applied to the gas ionizing unit. And a second voltage applying means for applying the voltage.

According to a second aspect of the present invention, gas introducing means for introducing a gas into the sample processing chamber, a filament arranged in the sample processing chamber for generating thermoelectrons by being heated, and a filament for heating the filament are heated. A heating power source for performing a cleaning operation, a parking mechanism that is disposed in the sample processing chamber and to which a member to be cleaned such as a sample or a probe is attached,
First voltage applying means for selectively applying a positive voltage or a negative voltage to the member to be cleaned, and the thermoelectrons generated in the sample processing chamber are accelerated to interact with the gas. Gas ionization means for ionizing the gas, second voltage application means for applying a positive voltage to the gas ionization means when necessary, a position between the filament and the member to be cleaned, or the filament It is characterized in that a moving means for selectively moving and setting the gas ionization means is provided at a position apart from the space to be cleaned.

[0014]

In the cleaning device using thermoelectrons according to the first aspect of the present invention having such a configuration, the gas is introduced into the sample processing chamber by the gas introduction means at a predetermined pressure. In this state, the filament is heated by the heating power source, a negative voltage is applied to the member to be cleaned by the first voltage applying means, and a positive voltage is applied to the gas ionizing means by the second voltage applying means. To be done. When the filament is heated, thermoelectrons e are generated from the filament, and the thermoelectrons are pulled and accelerated by the positive voltage applied to the gas ionization means, and the gas inside the ultra-high vacuum sample processing chamber near the gas ionization means. Interacts with the gas to be ionized and become positive gas ions.
Further, the gas ions are pulled and accelerated by the negative voltage applied to the member to be cleaned and vigorously collide with the member to be cleaned. Due to the ion bombardment caused by the collision of the gas ions, the gas ions sputter deposits adhering to the surface of the member to be cleaned to clean the member to be cleaned. In particular, by setting the filament to approximately the ground potential, most of the gas ions collide only with the member to be cleaned, which is applied with a negative voltage, and the other parts are not sputtered. Therefore, in the cleaning apparatus according to the first aspect of the present invention, the adhered matter that adheres to the member to be cleaned by ion bombardment and cannot be removed by the electron impact heating method can be reliably removed. That is, it is possible to obtain the same effects as those obtained by the conventional cleaning such as etching using an ion gun.

Further, in the conventional ion gun cleaning method, the acceleration speed of the ions from the ion gun is high,
Moreover, since the source is narrowed down, it is difficult to perform alignment for causing the ions to collide with the member to be cleaned. However, in the cleaning method according to the present invention, since a negative voltage is applied to the member to be cleaned, the gas ions are removed from the member to be cleaned. It will surely collide with, and alignment will be extremely easy.

Further, in the invention of claim 2, the moving means selectively causes the gas ionization means to be located either at a position between the filament and the member to be cleaned or at a position deviated from between the filament and the member to be cleaned. It will be moved and set. Then, when the gas ionization means is set at a position between the filament and the member to be cleaned, the member to be cleaned is cleaned by the ion bombardment method as in the first aspect of the invention. Further, when the gas ionization means is set at a position apart from between the filament and the member to be cleaned, the member to be cleaned is cleaned by the conventional electron impact heating method. Thus, in the invention of claim 2,
Cleaning is performed by two methods, that is, the cleaning by the electron impact heating method and the cleaning by the ion impact method.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view similar to FIG. 5, showing an example of an embodiment in which the thermoelectron cleaning device according to the present invention is applied to a UHV-STM. In addition,
The same components as those of the conventional UHV-STM described above are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, in the cleaning apparatus of this example, the filament 23 and the sample 4 in the conventional cleaning apparatus in the ultra-high vacuum sample processing chamber 2 shown in FIG.
And a gas ionization means 26 composed of a grid or a mesh for ionizing argon (Ar) gas.
Is provided. Further, in this example, a first voltage applying power source 25 'for applying a negative voltage to the sample 4 and a second voltage applying power source 27 for applying a positive voltage to the gas ionization means 26 are provided. Has been. Further, a gas cylinder 29 is connected to the ultra-high vacuum sample processing chamber 2 via a gas introduction valve 28. Ar gas is stored in the gas cylinder 29. The gas in the gas cylinder 29 may be an inert gas other than Ar gas, but Ar gas is most preferable in consideration of the weight of the gas. Another configuration of this example is the conventional UHV-STM shown in FIGS.
1 and the configuration of the cleaning device.

In the cleaning apparatus of the present embodiment thus constructed, the sample 4 is attached to the parking mechanism 3 in the ultra-high vacuum sample processing chamber 2 as in the conventional case described above, and the ultra-high vacuum sample processing chamber is provided. The inside of 2 is made into an ultra-high vacuum state. Then, by operating the gas supply valve 28, it is introduced only own the Ar gas of the gas cylinder 29 to the ultra high vacuum sample processing chamber 2 constant pressure (e.g., 10 ^@ 4 -10 ^over about 3 Pa).

Next, the filament heating power source 24 supplies a current of several amperes to the filament 23 to heat the filament 23, and the second voltage applying power source 27 causes the gas ionization means 26 to have a positive voltage (eg, 50 to several 100V), and a negative voltage (for example, several 100 to 1000V) is applied to the sample 4 via the parking mechanism 3 by the first voltage applying power supply 25 '.

When the filament 23 is heated, thermoelectrons e are generated from the filament 23, and the thermoelectrons e are pulled and accelerated by the positive voltage applied to the gas ionization means 26, and near the gas ionization means 26. Ar ⁺ ions are generated by interacting with Ar gas in the ultra-high vacuum sample processing chamber 2 to ionize Ar gas. Further, the Ar ⁺ ions are pulled and accelerated by the negative voltage applied to the sample 4, and vigorously collide with the sample 4. The ion bombardment caused by the collision of Ar ⁺ ions causes Ar ⁺
The ions sputter deposits attached to the surface of the sample 4 to clean the sample 4. At this time, since the filament 23 is almost at the ground potential, most of the Ar ⁺ ions collide only with the sample 4 applied to the negative voltage, and the other portions are not sputtered. The deposits on the sample 4 are efficiently removed.

As described above, according to the cleaning apparatus of this embodiment, the gas ionization means 26 accelerates the thermoelectrons e to
Ionize Ar gas by interacting with r gas,
Further, since the generated Ar ⁺ ions are violently collided with the sample 4, it is possible to surely remove the adhering substances which are adhered to the sample 4 due to the collision and cannot be removed by the electron impact heating method. Like That is, it is possible to obtain the same operation and effect as the conventional cleaning such as etching with an ion gun.

Further, since most of Ar ⁺ ions bombard only the sample 4, the deposits on the sample 4 can be efficiently removed. In that case, Ar to the ultra-high vacuum sample processing chamber 2
Since it is not necessary to introduce gas so much, the degree of vacuum in the ultra-high vacuum sample processing chamber 2 can be hardly reduced.

Further, in the conventional ion gun cleaning method, the acceleration speed of the ions from the ion gun is high,
Moreover, since the source is narrowed down, it is difficult to perform alignment for causing the ions to collide with the sample 4, but in the cleaning method according to this example, a negative voltage is applied to the sample 4,
Ar ⁺ ions can be reliably collided with the sample 4,
Alignment becomes extremely easy.

Further, in the cleaning method according to the present embodiment, the gas ionization means 26 is simply interposed between the filament 23 and the sample 4 and a positive voltage is applied to the gas ionization means 26, so that the cleaning device is large. In addition, the cost can be suppressed.

FIG. 2 is a view similar to FIG. 1 showing another example of the embodiment of the present invention. The above-mentioned conventional UHV-
The same components as those of the STM and the example shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 2, this example is an example of cleaning the probe 5 by the cleaning device shown in FIG. 1 instead of cleaning the sample 4. Therefore, the configuration of the cleaning device of this example is exactly the same as the configuration of the cleaning device shown in FIG.

After attaching the probe 5 to the parking mechanism 3 as in the conventional case described above, ion bombardment due to collision of Ar ⁺ ions with the probe 5 is carried out in the same manner as the cleaning of the sample 4 shown in FIG. The probe 5 is cleaned with.

As described above, in this example, the same action as the above-described cleaning action by the ion bombardment of the sample 4 is performed, and therefore, the same effect is obtained as the above-described cleaning effect.

FIG. 3 is a view similar to FIG. 1 showing still another example of the embodiment of the present invention, (a) is a view for explaining cleaning by an electron impact heating method, and (b) is an ion impact. It is a figure explaining the cleaning by the method. The same components as those of the conventional UHV-STM and the example shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

The cleaning apparatus of this example is designed so that both the cleaning by the electron impact heating method shown in FIG. 3A and the cleaning by the ion impact method shown in FIG. 3B are performed. Explaining this example in detail, the attachment portion 2a of the two connecting portions 30 and 31 of the filament 23 and the filament heating power source 24 on the side wall of the ultra-high vacuum sample processing chamber 2 is connected via the linear movement bellows 32. And is connected to the other portion 2b of the side wall.
That is, the connecting portions 30 and 31 are linear movement bellows 32.
It can be moved linearly to the left and right by driving. As a result, the filament 23 is disposed between the cleaning position shown by the electron impact heating method and the cleaning position by the ion bombardment method (not shown: to the left of the shown position).
It is possible to move in a straight line.

A support rod 33 for supporting the gas ionization means 26 is provided on the side wall of the ultrahigh vacuum sample processing chamber 2 so as to be rotatable about its longitudinal axis, and the support rod 33 is also provided.
Rotation drive means 34, for example, including a magnet, is provided for rotating the. This rotation driving means 34
The gas ionization means 26 is located between the filament 26 and the parking mechanism 3 and the unused position shown in the drawing, which is out of the space between the filament 26 and the parking mechanism 3, by driving the motor. It is rotatably movable with respect to a use position (not shown). And
The gas ionization means 26 is in an unused position when the filament 23 is in the cleaning position by the electron impact heating method as shown in FIG. 3 (a), and the filament 23 is in the ion impact method as shown in FIG. 3 (b). When it is in the cleaning position, the setting position is selectively set to the use position.

Further, as shown in FIG. 3A, when the filament 23 is set at the cleaning position by the electron impact heating method and the gas ionization means 26 is set at the non-use position, the cleaning is performed by the electron impact heating method. Sample 4
As the voltage applying power source for applying a voltage to the sample, the illustrated voltage applying power source 25 is used, and a positive voltage is applied to the sample 4. In that case, no voltage is applied to the gas ionization means 26 in the non-use position, the gas introduction valve 28 is closed, and Ar gas is not introduced into the ultrahigh vacuum sample processing chamber 2.

Further, as shown in FIG. 3B, when the filament 23 is set at the cleaning position by the ion bombardment method and the gas ionization means 26 is set at the use position, the cleaning is performed on the sample 4 by the ion bombardment method. The voltage applying power source for applying the voltage is the first voltage applying power source 25 '.
Is used, and a negative voltage is applied to the sample 4. That is, a positive or negative voltage is selectively applied to the sample 4 depending on the cleaning method. Further, a second voltage applying power source 27 is used as a voltage applying power source for applying a voltage to the gas ionizing means 26, and a positive voltage is applied to the gas ionizing means 26.

In the cleaning apparatus of this example having such a configuration, the sample 4 and the probe 5 are made by the electron impact heating method.
And the like can be cleaned, and the member to be cleaned by the ion bombardment method can be cleaned. Therefore, according to the cleaning of this example, it is possible to obtain the effect of having both the advantages of the cleaning by the electron impact heating method and the advantages of the ion impact method.

In the example shown in FIGS. 3 (a) and 3 (b), the connecting portion 30, on the side wall of the ultra-high vacuum sample processing chamber 2,
The attachment portion of 31 is linearly movable to the left and right by the linear movement bellows 32 to move the filament 23. However, as a means for moving the filament 23, the filament 23 is moved to a position where it does not interfere with the gas ionization means 26. Any other means can be used, if possible. Similarly, as the gas ionization means 26, a rotation driving means other than the electric motor can be used. Further, the gas ionization means 26 may be moved between the use position and the non-use position by a rectilinear motion other than the rotational motion.

In each of the above-mentioned examples, the case where the cleaning device of the present invention is applied to the UHV-STM1 has been described. However, the present invention is provided with a cleaning device for cleaning the member to be cleaned using thermoelectrons. As long as it is present, it can be applied to any other device such as various electron optical devices such as an electron microscope and a surface analysis device or various analysis devices such as an element / structure analysis device.

Further, it is possible to provide a dedicated cleaning chamber which communicates with the ultra-high vacuum sample processing chamber 2 and clean the sample 4 and the probe 5 in this cleaning chamber. Further, a conventional ion gun may be used together with the cleaning device of the present invention to clean the sample 4, the probe 5, and the like. This cleaning by using the ion gun together is suitable for cleaning, for example, by deeply digging only a part of the sample.

[0039]

As is apparent from the above description, according to the cleaning device using thermoelectrons of the present invention, the gas ions are caused to interact with the thermoelectrons by the gas ionizing means to force the ionized gas toward the member to be cleaned. Since the collision is performed well, it is possible to surely remove the adhering matter that is adhered to the member to be cleaned due to the ion bombardment due to the collision and cannot be removed by the electron impact heating method. That is,
It is possible to obtain the same operation and effect as the conventional cleaning such as etching with an ion gun.

In particular, by setting the filament to approximately the ground potential, most of the gas ions are bombarded only with the member to be cleaned to which a negative voltage is applied, so that the deposits on the member to be cleaned can be efficiently removed. . In that case, it is not necessary to introduce much gas into the sample processing chamber, so that the pressure in the sample processing chamber is hardly changed.

Further, in the conventional ion gun cleaning method, the acceleration speed of the ions from the ion gun is high,
Moreover, since the source is narrowed, it is difficult to align the ions to collide with the member to be cleaned. However, according to the cleaning method of the present invention, since a negative voltage is applied to the member to be cleaned, a positive gas is applied. Ions can surely collide with the member to be cleaned, and alignment becomes extremely easy.

Further, according to the invention of claim 1, since the gas ionization means is simply interposed between the filament and the member to be cleaned and a positive voltage is applied to the gas ionization means, the cleaning device is It does not become large in size, the increase in cost can be suppressed, and the device can be formed relatively inexpensively.

According to the second aspect of the present invention, the moving means selectively causes the gas ionization means to be located either at a position between the filament and the member to be cleaned or at a position deviated from between the filament and the member to be cleaned. Since it can be moved and set to, cleaning by the ion bombardment method and cleaning by the electron bombardment heating method can be performed. Therefore, according to the invention of claim 2, the same effect as in the invention of claim 1 by the ion bombardment method and the effect by the conventional electron bombardment heating method, that is, the deposits that are relatively easy to remove are simple in structure and simple. It is possible to obtain the effect that it can be removed by various methods.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of an embodiment when a cleaning device using thermoelectrons according to the present invention is applied to an ultrahigh vacuum scanning tunneling microscope.

FIG. 2 is a diagram schematically showing another example of the embodiment in which the thermoelectron cleaning device according to the present invention is applied to an ultra-high vacuum scanning tunneling microscope.

FIG. 3 schematically shows still another example of the embodiment in which the thermoelectron cleaning device according to the present invention is applied to an ultra-high vacuum scanning tunneling microscope, and (a) shows cleaning by an electron impact heating method. FIG. 4B is a diagram showing cleaning by the ion bombardment method.

FIG. 4 is a diagram schematically showing an example of a conventional ultra-high vacuum scanning tunneling microscope.

FIG. 5 is a diagram schematically showing a conventional device for cleaning a sample, a probe, etc. by an electron impact heating method.

[Explanation of symbols]

1. Ultra high vacuum scanning tunneling microscope (UHV-ST
M), 2 ... Ultra-high vacuum sample processing chamber, 3 ... Parking mechanism,
4 ... Sample, 5 ... Probe, 6 ... Image observation chamber, 7 ... STM stage, 8 ... First transport mechanism, 9 ... First core rod, 10 ... First gripping portion, 11 ... First magnet, 12 ... 1 guide rail,
13 ... 2nd conveyance mechanism, 14 ... 2nd core rod, 15 ... 2nd holding part, 16 ... 2nd magnet, 17 ... Guide rail, 18
... first connection passage, 19 ... first gate valve, 20 ... exchange chamber, 21 ... second connection passage, 22 ... second gate valve, 2
3 ... Filament, 24 ... Filament heating power source, 2
5 ... Power supply for voltage application, 25 '... Power supply for first voltage application, 2
6 ... Gas ionization means, 27 ... Power source for applying second voltage, 2
8 ... Gas introduction valve, 29 ... Gas cylinder, 30, 31
... Connection part, 32 ... Bellows for linear movement, 33 ... Support rod,
34 ... Rotational drive means, e ... Thermoelectrons, Ar ⁺ ... Argon gas ions

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Claims (2)

(57) [Claims] 1. A gas introducing means for introducing a gas into a sample processing chamber, a filament which is disposed in the sample processing chamber and generates thermoelectrons when heated, and a heating power source for heating the filament. A parking mechanism which is disposed in the sample processing chamber and to which a member to be cleaned such as a sample or a probe is attached; a first voltage applying unit which applies a negative voltage to the member to be cleaned; Arranged gas ionizing means for accelerating the generated thermoelectrons to interact with the gas to ionize the gas, and second voltage applying means for applying a positive voltage to the gas ionizing means. And a thermionic cleaning device. 2. A gas introducing means for introducing a gas into the sample processing chamber, a filament which is disposed in the sample processing chamber and generates thermoelectrons when heated, and a heating power source for heating the filament. A parking mechanism disposed in the sample processing chamber, to which a member to be cleaned such as a sample or a probe is attached, and a first voltage applying means for selectively applying a positive voltage or a negative voltage to the member to be cleaned. A gas ionization means disposed in the sample processing chamber for accelerating the generated thermoelectrons to interact with the gas to ionize the gas, and a positive voltage is required for the gas ionization means when necessary. Second for applying
Voltage applying means and moving means for selectively moving and setting the gas ionization means to a position between the filament and the member to be cleaned or a position apart from between the filament and the member to be cleaned. A thermionic cleaning device.