JPH06119896A - Ion beam takeout device - Google Patents

Abstract

PURPOSE:To enable a deposit adhering to and accumulated on an electrode to be easily vaporized and removed by connecting a power supply and heating means for heating the electrode to a takeout electrode for taking out charged particles at the opening of a plasma generation chamber. CONSTITUTION:A switch group 12 is changed over after taking out an ion beam, and terminals 81 and 83 at each one side of the second and third takeout electrodes 10b and 10c are grounded. Concurrently, the power switch 13 of a power supply and heating means 15 is closed, thereby applying the voltage of a heating electric power source 14 to the grid electrode plates 5 of the electrodes 10b and 10c. Also, the electrode plates 5 are caused to generate heat to such level as not reaching overheat state, and a deposit such as phosphorus oxide adhering to the electrodes 10b and 10c is made to evaporate. Vaporized gases are removed via a vacuum evacuation device and the operation of a means 15 is stopped for a suitable time. As a result, the electrode plates 5 can be restored to a condition before use, without any need of overhaul cleaning, and can further maintain function as an electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion beam extraction apparatus for generating charged particles such as ions, and more particularly to an ion beam extraction apparatus capable of easily removing deposits deposited on an extraction electrode. is there.

[0002]

2. Description of the Related Art A film can be formed on the surface of an object by ionizing and ejecting a substance and irradiating and colliding the ion with the object. The ion beam extraction device that serves as the ion generation source first introduces a gaseous material that is a source of ions, discharges gas in this gas atmosphere to generate plasma, and charges the ions from the plasma. The desired ions are extracted by extracting the particles.

Conventionally, an ion beam extraction apparatus generally has an opening provided at one end of a plasma generation chamber for generating plasma and holding the plasma, and an extraction electrode for extracting charged particles such as ions from the plasma in the opening. It will be provided. The extraction electrode is formed in a mesh shape, a slit shape, or a perforated plate shape so that the charged particles accelerated by the electric field formed by the extraction electrode can easily slip through. Hereinafter, the electrode having such a gap will be referred to as a grid.

Argon or phosphine (PF ₃ ) gas is introduced into the plasma generating chamber. Then, argon ions or phosphorus ions can be extracted from the plasma by an electric field formed by the extraction electrode, and the surface of an object such as a semiconductor substrate, which is the object, can be irradiated and injected with argon or phosphorus. Further, the plasma generation chamber is evacuated by a vacuum exhaust device, so that unnecessary substances are constantly discharged and a stable pressure is maintained.

[0005]

By the way, the extraction electrode is a grid as described above. Most of the argon ions and phosphorus ions pass through the gaps in the grid and reach the object, but it is inevitable that some of them will collide with the grid. In the case of argon, the charged argon becomes argon gas and is exhausted by the exhaust device. In the case of phosphorus, phosphorus may form a phosphorus compound or the like, which is not exhausted and remains attached to the grid. Then, when the phosphorus compound gradually accumulates on the grid and covers the surface of the grid, the electrical conductivity of the phosphorus compound is not good, which hinders the formation of an electric field and gradually loses the function as the extraction electrode of the grid. become. The formation of the insulating film on the grid is fatal to the ion beam extractor.

In order to avoid such a situation, cleaning of the grid is usually encouraged. Cleaning of the grid is performed by disassembling the device, taking out the grid, and then using a brush, a file, a chemical, or the like after using the ion beam extraction device.
The extraction electrode is attached to the opening of the plasma generation chamber by screws or the like so that disassembly and cleaning can be easily performed.

However, the ion beam extraction device is
Since the pressure is reduced to a high vacuum during use, the plasma generation chamber is a container having a high sealing property and is connected to the processing chamber and the like with a good sealing property. Therefore, when attaching / detaching the extraction electrode, it is necessary to open / close this container having a high sealing property. When the container is opened and closed, the inside of the container becomes atmospheric pressure and various substances in the air such as moisture enter the container. Therefore, when the use is restarted, the pressure must be reduced from the atmospheric pressure to discharge all impurities. After all, it was troublesome to restart the use, which was a problem.

Further, disassembly and cleaning is a manual work using a brush, a file, chemicals, etc., and it is troublesome to be careful of damage to the grid. And after disassembling and cleaning,
The work of sealing the container is also complicated and requires attention in order to maintain high sealing performance.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an ion beam extractor capable of easily removing deposits adhering and depositing on extractor electrodes.

[0010]

Means for Solving the Problems In order to achieve the above object, the present invention provides an energization heating means for energizing an extraction electrode to heat the extraction electrode by energizing the extraction electrode in order to evaporate a deposit attached to the extraction electrode. Is connected.

[0011]

With the above construction, when the energization heating means is operated after the ion beam extraction apparatus has been used, the extraction electrode is heated, and the heat causes the deposit attached to the extraction electrode to evaporate. Evaporated gas is removed by a vacuum exhaust device. In this way, the extraction electrode is in a state of no deposit, and the function as an electrode is maintained.

Since the extraction electrode has no deposit,
There is no need to disassemble and clean the ion beam extractor.
For this reason, there is no risk of damage during cleaning, and since it is not necessary to open and close the vacuum container, the complexity of the sealing work is eliminated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory view of an ion beam extraction apparatus according to the present invention. As shown in the figure, the plasma chamber 1 has a cylindrical outer shell 2 having one end opened and the other end closed. The plasma chamber 1 is provided with an introduction part for introducing a gas such as phosphine into the plasma chamber 1 and an electrode (not shown) for performing arc discharge in the plasma chamber 1. The plasma can be generated in the plasma chamber 1 by performing arc discharge in the gas atmosphere.

A flange 4 extending radially inward from the opening 3 is provided integrally with the outer shell 2 of the plasma chamber 1. Three grid electrode plates 5 are attached to the opening 3 of the plasma chamber using the flange 4. The grid electrode plate 5 is made of a material such as graphite and tungsten which has high heat resistance and conductivity and is hard to be sputtered. The planar shape of the grid electrode plate 5 is shown in FIG.
As shown in (a), it is formed in a circular shape so as to cover the opening 3 of the plasma chamber, has an annular edge 6 at its outer peripheral portion, and has a large number of fine width slits at its inner peripheral portion. 7 are formed at fine intervals. The edge 6 on the outer peripheral portion of the grid electrode plate 5 has a thickness larger than that of the inner peripheral portion, and is easily attached to the flange 4. At least two connecting terminals 8 for applying a voltage are provided on the edge 6 of the outer peripheral portion. In the present embodiment, the connection terminals 8 are provided at positions facing each other with the center interposed, and a voltage can be applied between both electrodes to energize the rim 6 of the outer peripheral portion and the bone portion between the slits 7. . Further, the electric potential for drawing out the plasma is also applied by utilizing this connection terminal 8.

The grid electrode plates 5 are stacked on each other via insulating spacers 9 and attached to the flange 4 via insulating spacers 9. Each of the grid electrode plates 5 serves as the extraction electrode 10 in a broad sense, but they have different roles by being given different electric potentials.
Here, the first, the second, the third
Of the extraction electrode.

To the first extraction electrode 10a, the connection terminal 8 is opened and no electric potential is applied. Therefore, it is also called a floating electrode. Since the floating electrode faces the inside of the plasma chamber 1, the floating electrode approaches the electric potential of the plasma and is confined, and contributes to the formation of the boundary of the plasma during extraction.

The third extraction electrode 10c is applied with a negative potential of several tens kV with respect to the outer shell 2 of the plasma chamber 1 at one connection terminal 81. This is the potential for pulling positively charged particles out of the plasma. In this embodiment, the potential of the connection terminal 81 is the ground potential, and the outer shell 2 of the plasma chamber 1 has a high potential.

The second extraction electrode 10b is connected to one of the connection terminals 83 by 100 to 1k with respect to the third extraction electrode 10c.
A negative potential of V is applied. This is a potential that prevents backflow of electrons from the outside of the plasma chamber 1.

FIG. 1 shows a power source for applying each potential to the extraction electrode and the outer shell of the plasma chamber and a switch group 12 for switching the connection. The opening and closing of each switch of the switch group 12 is switched depending on whether or not the ion beam extraction is performed. FIG. 1 shows a connection state when ion beam extraction is performed. The third extraction electrode 10c is grounded by a switch 121, and the second extraction electrode 10b is switched by a switch 122 via a power source.
A negative potential of 0 to 1 kV is applied to the outer shell 2 of the plasma chamber 1.
Is supplied with a positive potential of several tens of kV from a switch 124 via a power source. When the ion beam extraction is not performed, the switches 122 and 124 are opened and the switch 123 is closed instead, and the second extraction electrode 10b is grounded.

The heating power source 14 is connected to the remaining connection terminals 82 and 84 of the second extraction electrode 10b and the third extraction electrode 10c through the energizing switch 13, respectively. The heating power source 14 may be either AC or DC. The energizing switch 13 is closed when deposits are removed when the ion beam extractor is not in use. One side electrode of the heating power source 14 is grounded, and the second extraction electrode 10b and the third extraction electrode 10c can be energized by closing the energizing switch 13. That is, the energizing switch 13 and the heating power source 14 are the energizing and heating means 15 that energizes the extraction electrode 10 to heat the extraction electrode 10.

Next, the operation of the embodiment will be described.

After the extraction of the ion beam is completed, the switch group 12 is switched to ground the connection terminals 81 and 83 of one of the second extraction electrode 10b and the third extraction electrode 10c, respectively. At the same time, the energizing switch 13 of the energizing heating means 15
When is closed, a voltage is applied between the connection terminals 8 by the heating power source 14 to the grid electrode plates 5 of the second extraction electrode 10b and the third extraction electrode 10c. In this way, when the grid electrode plate 5 is energized and a current flows through each bone forming the slit 7, the grid electrode plate 5 generates heat. The grid electrode plate 5 is heated by this heat generation.
It is performed to such an extent that the deposit such as phosphorous oxide adhered to is evaporated, and the grid electrode plate 5 is not overheated.
Evaporated gas generated at this time is removed by a vacuum exhaust device. After energization for an appropriate time, energization heating means 1
When 5 is stopped, the deposit is wiped from the grid electrode plate 5, and the grid electrode plate 5 is restored to the state before use without performing disassembly and cleaning, and the function as an electrode is maintained.

As described above, according to the ion beam extraction apparatus of the present invention, the extraction electrode 10 can be restored to the state without deposits by simply performing a simple switch operation. No need to disassemble and clean. For this reason, there is no risk of damage during cleaning, and since it is not necessary to open and close the vacuum container, the complexity of the sealing work is eliminated.

In order to more effectively realize the present invention, the shape of the grid electrode plate 5 is as shown in FIG.
It is also possible that the outer peripheral portion has no thickness. That is, FIG.
In the embodiment (b), the slits 7 are formed so as to extend up to the periphery of the grid electrode plate 5 except for the periphery of the connection terminal 8, and the grid electrode plate 5 has a uniform thickness. According to this configuration, it is possible to prevent a large amount of current from flowing to the outer peripheral portion during heating by energization, which is efficient.

Next, the square grid electrode plate 5 shown in FIG. 2 (c) has a shape suitable for an ion beam extractor having a square opening for forming a square ion beam. There is. Blank areas without slits are formed on the upper and lower sides of the grid electrode plate 5. The margin is provided to facilitate the attachment to the flange.

In this embodiment, the grid electrode plate 5 is
Although the structure having the slit 7 is adopted, the same operational effect can be obtained even if a mesh or a porous material is provided instead of the slit 7.

Further, the heating power source 14 may individually distribute the voltage according to the amount of the deposits of the second extraction electrode 10b and the third extraction electrode 10c, or one common voltage may be used if there is no difference. A common voltage or common current may be applied from the heating power source.

[0029]

The present invention exhibits the following excellent effects.

(1) It is not necessary to disassemble and clean the ion beam extractor, which saves the trouble.

(2) Since the disassembly and cleaning are not performed, the troublesomeness of the sealing work is eliminated.

(3) Since deposits are removed while the pressure is reduced, it is easy to restart use.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an ion beam extractor equipped with an unnecessary deposit removing device according to an embodiment of the present invention.

FIG. 2 is a plan view of a grid electrode plate used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma chamber 5 Grid electrode plate 8 Connection terminals 10, 10a, 10b, 10c Extraction electrode 15 Electric heating means

Claims (1)

[Claims] 1. An ion beam extraction apparatus having an extraction electrode for extracting charged particles in an opening of a plasma generation chamber, wherein the extraction electrode is energized to vaporize a deposit adhering to the extraction electrode. An ion beam extraction apparatus, characterized in that an electric heating means for heating the extraction electrode is connected.