KR101726189B1 - Repeller for ion implanter - Google Patents

Abstract

A repeller for an ion implanter according to the present invention is a repeller installed inside an arc chamber for an ion implanter facing a cathode to push out electrons emitted from the cathode. The repeller comprises: a repeller fixing unit configured to fix the repeller on one side of the arc chamber; an electron reflecting unit connected to the repeller fixing unit and having a surface facing the cathode; and a repeller protruding unit configured to protrude from the electron reflecting unit toward the cathode.

Description

Repeller for ion implanter}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a repeller for an ion implanter, and more particularly, to a repeller provided in an arc chamber of an ion implanter to push out electrons emitted from a cathode inside an arc chamber to improve ion production efficiency.

The repeller is disposed inside the arc chamber of the ion generating device for ion implantation used for manufacturing a semiconductor device and reflects electrons emitted from the cathode. The ion implanter currently used is an ion generating device for generating ions to be doped with impurities. And an ion analysis unit for controlling the kind and energy of generated ions.

The ion generating device heats the filament to emit thermoelectrons, and accelerates the emitted thermoelectrons by an electric field while colliding with the injected ion source gas to generate ions. In this case, a method of releasing the thermoelectrons is a method of directly heating a tungsten filament to emit thermoelectrons and a method of accelerating a thermoelectron emitted from a tungsten filament to a cathode to secondarily emit electrons again from the cathode. Deterioration of the filament material can be prevented and the replacement cycle of parts can be improved. The ion generating device is provided with a repeller opposed to the cathode. The repeller reflects the electrons emitted from the cathode toward the cathode so that electrons are concentrated in a predetermined region. A predetermined voltage may be applied to the repeller so as to reflect electrons. In the ion generating device for an ion implanter, a gas which is a source of ions is injected, and in the arc chamber, the ion source gas is decomposed while colliding with electrons. At this time, a part of the decomposed gas may be deposited on the surface of the wall of the repeller or the arc chamber. The deposited material is peeled off from the surface of the re-pellet in the course of a thermal cycle to contaminate the inside of the arc chamber, There arises a problem that can cause a short circuit between the repeaters.

Japanese Patent Application Laid-Open No. 2010-073387 discloses a prior art concerning a short between an arc chamber and a repeller for an ion implanter. In the above prior art, the cathode 20 is disposed above the re-peller 30 in consideration of the influence of gravity when the conductive material deposited on the reflector 34 of the re- 30 on the holding side of the reflecting portion 34 of the repeller 30 so as to prevent the conductive material from falling off and prevent the short circuit from occurring by blocking the gap 14 with the arc chamber 10, And the second bank 19 is provided at an end of the arc chamber 10 as an auxiliary means for this.

The repeller having such a structure has a limit that is not applicable when it is provided at a position facing horizontally with the cathode.

Therefore, even when the cathode and the repeller are horizontally opposed to each other, the material deposited on the reflecting portion of the repeller, and the chamber well surface of the upper end of the repeller, is peeled off and then deposited on the gap with the arc chamber to cause a short There is a great need to develop a repeller capable of performing an ion implantation reaction while maximizing the replacement time of components.

Therefore, a first problem to be solved by the present invention is to provide a plasma processing apparatus capable of preventing the short circuit between the repeller and the arc chamber from occurring even if the deposition material deposited on the wall of the repeller or the arc chamber is peeled, To thereby improve the ion production efficiency.

A second object of the present invention is to provide an arc chamber including a repeller for the ion implanter.

In order to achieve the first object of the present invention, there is provided a repeller for opposing a cathode provided inside an arc chamber for an ion implanter and pushing out electrons emitted from the cathode, wherein the repeller is fixed to one side of the arc chamber And a repeller having a surface opposed to the cathode and a repeller protrusion protruding in the direction of the cathode from the electron reflection portion, to provide.

According to an embodiment of the present invention, the repeller projecting portion may be spaced apart from the one end of the electron reflection portion at a predetermined interval.

According to another embodiment of the present invention, the repeller projection and the lower portion of the arc chamber are spaced apart by an interval of 8 mm to 16 mm.

According to another embodiment of the present invention, the repeller projecting portion may have an inclination angle in the direction of the center of the electron reflection portion.

According to another embodiment of the present invention, the repeller projecting portion may have an inclination angle in the direction of the outer periphery of the electron reflection portion.

According to another embodiment of the present invention, it is preferable that the electron reflecting portion of the repeller is circular, and the protruding portion of the repeller protrudes to a height of 0.3R to 0.5R of the radius of the electron reflecting portion.

According to another embodiment of the present invention, when the radius of the electron reflection portion is R, the electron reflection portion of the repeller is circular, and the repeller projection portion is spaced apart from the outer portion of the electron reflection portion by a length of 0.1R to 0.6R Is formed at a predetermined position.

In order to achieve the second object, the present invention provides an arc chamber for an ion implanter including the repeller.

The repeller for an ion implanter of the present invention has the following effects.

1. Since the repeller protrusions are spaced apart at a predetermined distance from one end of the electron reflection portion, the possibility that the deposition material peeled off from the wall of the repeller or arc chamber connects between the repeller and the arc chamber to cause a short circuit can be reduced.

2. Since the protrusions of the repeller have an inclination angle in the direction of the central part or the outer part of the electron emitting part, the deposition material peeled off from the liner is guided to fall into the area of the direction of the cathode, not the bottom part of the repeller, The short circuit can be prevented more effectively.

3. Since the protruding portion of the repeller is formed in the outer portion of the electron emitting portion, the direction of electron repulsion by the repeller can be guided to the center portion of the arc chamber to improve ion production efficiency.

FIG. 1 shows a conventional arc chamber for an ion implanter.
FIG. 2 is a view for explaining the deposition of deposits in the arc chamber as the ion implantation process proceeds. FIG.
FIG. 3 is a view for explaining a process in which electrical short-circuiting occurs between the refeller and the arc chamber when the deposition material in the arc chamber is peeled off.
4 is a view for explaining a reason why a short circuit is likely to occur between the repeller and the arc chamber in the conventional arc chamber for an ion implanter.
5 shows the structure of a repeller for an ion implanter of the present invention.
6 shows various embodiments of the repellers for the ion implanter of the present invention.
FIGS. 7 and 8 are views for explaining a region in which the deposition material falls in the repeller for the ion implanter of the present invention in which the inclination angle is formed.
9 is a view for explaining a repeller structure for an ion implanter according to the present invention, in which electrons pushed out from a repeller move to a central portion of an arc chamber.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

A repeller for an ion implanter according to the present invention is a repeller for opposing a cathode provided inside an arc chamber for an ion implanter and pushing out electrons emitted from the cathode, An electron reflecting portion connected to the feller fixing portion and the repeller fixing portion and having a surface facing the cathode, and a repeller protruding portion protruding from the electron reflecting portion in the cathode direction.

In the repeller for an ion implanter of the present invention, the projecting portion is formed on the surface of the electron reflecting portion facing the cathode. The projecting portion has an effect of preventing a short circuit between the repeller and the arc chamber due to peeling of the deposition material generated during the ion implantation process and an effect of enhancing the ion generation efficiency by concentrating the electrons pushing from the repeller to the central portion of the arc chamber.

First, the protrusion prevents the peeled deposition falling on the periphery of the repeller from connecting the repeller to the chamber bottom wall to prevent electrical shorting. In the present invention, the maximum length of the deposition material to be peeled off from the repeller or the chamber wall is measured to derive the distance between the projection and the bottom wall of the arc chamber that are prevented from being short-circuited by the deposition material. It is also possible to form a tilting angle in the horizontally extending portion of the protrusion to prevent the deposited material from falling off the arc chamber wall in the area around the repeller or the repeller to fall into the area close to the repeller, resulting in a short circuit between the repeller and the arc chamber .

Further, the protrusion causes the surface of the repeller to protrude from the outer periphery toward the cathode, rather than the center, so that the electrons pushed out from the repeller are concentrated to the center of the arc chamber. Electrons moving to the center of the arc chamber have a longer path to reach the wall of the arc chamber, resulting in improved ion production efficiency within the arc chamber.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.

FIG. 1 shows a conventional arc chamber for an ion implanter. Referring to FIG. 1, an arc chamber 100 includes a filament 101, a cathode 102, a repeller 103, and a chamber wall 104. The region of the arc chamber 100 where the plasma is generated is surrounded by the chamber wall 104, and a plasma is generated inside the arc chamber. In the process of generating the plasma, a gas having an element necessary for ion implantation is first injected through the gas injection unit 106 of the arc chamber. The filament 101 is heated to a high temperature to emit thermoelectrons and the released thermoelectrons are accelerated to the cathode 102 to heat the cathode. In the heated cathode, electrons are emitted, and the emitted electrons accelerate toward the arc chamber and collide with the gas to generate ions. Although not shown in the drawing, a magnet is provided around the arc chamber to increase the movement path of electrons, and electrons collide with gas inside the arc chamber due to the magnetic field generated by the magnet while spirally moving. At this time, a repeller 103 is provided on the opposite side of the cathode. The repeller pushes electrons moving toward the arc chamber from the cathode back to the center of the arc chamber. The ionized gases pass through the ion extraction unit 105 and are injected into the ion analysis unit.

FIG. 2 is a view for explaining the deposition of deposits in the arc chamber as the ion implantation process proceeds. FIG. Referring to FIG. 2, deposits are formed on the repeller 103 and the chamber wall 104. Deposits are formed by the deposition of a reactive material generated during the ionization process on the surface of the re-pellet or on the walls of the chamber, where the deposits often have conductivity and the stripped deposits may cause short circuits.

FIG. 3 is a view for explaining a process in which electrical short-circuiting occurs between the refeller and the arc chamber when the deposition material in the arc chamber is peeled off. 3 (a), deposits 200a, 200b, and 200c are formed on the repeller 103, the chamber upper wall 104a, and the chamber lower wall 104b as the ion implantation process proceeds. Next, referring to FIG. 3 (B), a part of the deposition material 200b is peeled off from the surface of the repeller 103 and falls toward the chamber lower wall 104b. Referring to FIG. 3 (c), the dropped deposition material 200b is positioned between the chamber lower wall 104b and the repeller 103, and a short circuit occurs between the repeller and the arc chamber. When a short circuit occurs between the repeller and the arc chamber, the power is cut off by the control circuit of the ion implanter, the process is stopped, the wafer in which the ion implantation is in progress is treated as defective, and the ion implanter is time- So productivity is a problem.

4 is a view for explaining a reason why a short circuit is likely to occur between the repeller and the arc chamber in the conventional arc chamber for an ion implanter. Referring to Fig. 4, the repeller 103 is spaced apart from the chamber upper wall 104a by a length of x between the chamber lower wall 104b. If the gap between the repeller and the chamber wall is wide, it is possible to prevent a short circuit caused by the deposition material. However, considering the ion generation efficiency in the arc chamber, x can not be reduced below a certain level. Therefore, if the deposition lengths (y1, y2, y3) on the surface of the repeller 103 and the deposition lengths (y4, y5) on the surface of the chamber upper wall 104a are larger than x, there is a high possibility of a short circuit. Although the depilator or the deposition material on the wall of the chamber is shown as being formed in a separate form from each other in the drawing, in reality, only a part of them may be peeled off in a state in which the whole film is formed.

5 shows the structure of a repeller for an ion implanter of the present invention. Referring to FIG. 5 (a), the repeller 303 of the present invention is fixed to one side of the arc chamber by the repeller fixing portion 303a. Although the rod-shaped repeller fixing portion is shown in the drawing, the repeller fixing portion is not limited to the shape as long as the position of the repeller can be fixed. For example, the repeller fixing portion may be formed in such a manner that the repeller fixing portion is connected to the rear periphery of the re- And there may be additional configurations for securing the repeller. The repeller includes an electron reflecting portion 303c for pushing electrons toward the cathode. The electron reflecting portion 303c may be circular, square, elliptical, or the like, and is preferably circular in consideration of the ion generation efficiency of the plasma.

The repeller projecting portions 303b are formed at a predetermined distance from the end of the electron reflecting portion 303c. In this structure, when the repeller projecting portion 303b is formed on the surface of the electron reflecting portion 303c of the repeller, the distance from the lower portion of the electron reflecting portion 303c to the chamber lower wall 104b does not change to x, The distance from the projection 303b to the chamber lower wall 104b is increased to z. Since the repeller projecting portion 303b protrudes from the electron reflecting portion 303c, it is difficult for the deposition material peeled off from the repeller or the chamber wall to fall between the lower portion of the electron reflecting portion 303c and the chamber lower wall 304b. The deposition material mainly falls on the left side of the repeller by the repeller projecting portion 303b. In this case, the distance between the projecting portion of the repeller and the lower wall of the chamber increases to z instead of x, 5 shows the peeled deposition material 200. When the length k of the deposition material 200 is smaller than z, it is more difficult to cause a short circuit between the repeller and the chamber wall. The distance between the protrusions 303b and the chamber lower wall 304b is preferably 8 to 16 mm since the maximum length of the deposited material peeled off from the repeller or chamber wall is likely to be in the range of less than 16 mm The maximum length distribution of the peeled deposits was obtained through experiments, it is listed in Experimental Example.

The repeller projecting portion extends from the surface of the electron-reflecting portion toward the cathode, and the extended portion may have an inclination angle. The inclination angle is preferably formed in a direction in which the cross-sectional area decreases as the repeller projection extends. This will be described with reference to FIG.

6 shows various embodiments of the repellers for the ion implanter of the present invention. 6 (A), the repeller projecting portion 303b extends horizontally in the direction of the cathode from the electron reflecting portion 303c. In this structure, the inclined angle is not formed either in the central portion of the electron reflecting portion 303c nor in the outer frame portion of the repeller projection portion 303b. Referring to FIG. 6 (B), the inclined angle is formed in the direction of the center of the electron reflecting portion 303c in the repeller projecting portion 303b. Referring to FIG. 6 (C), in the repeller projecting portion 303c, an inclination angle is formed in both the central portion and the outermost portion of the electron reflecting portion 303c.

FIGS. 7 and 8 are views for explaining a region in which the deposition material falls in the repeller for the ion implanter of the present invention in which the inclination angle is formed. Referring to FIG. 7, the deposition material 200b formed on the electron reflection portion of the repeller falls off in the cathode direction while colliding with the inclined surface of the repeller projecting portion in the peeling off process. At this time, the dropped deposition material is liable to be located in the repeller leaving area (Y), which is relatively less likely to be short-circuited than the re-peler-close area (X), where a short circuit is likely to occur. In this case, the inclination angle &thetas; 1 formed in the protruding portion of the repeller is preferably 20 to 60 degrees. If it is less than 20 degrees, there is a high possibility that the deposition material is caught in the protruding portion of the repeller, and if it exceeds 60 degrees, the deposition material may fall into the vicinity of the repeller. Referring to FIG. 8, an inclination angle is formed in the protruding portion of the repeller in the direction of the outer periphery of the electron reflection portion. At this time, the deposition material 200a deposited on the upper wall of the chamber is likely to fall on the inclined surface, and the possibility that the deposition material 200 falls to the separator leaving area Y is increased. At this time, the inclination angle? Is preferably 30 to 70 degrees. The inclined surface formed by the outer peripheral portion of the electron reflection portion has the effect of pushing the electrons from the refiller toward the outer peripheral portion of the chamber. Therefore, it is preferable to set the inclination angle to be larger than the inclination angle of FIG. Considering the ion production efficiency, it is preferable that the repeller projecting portion is formed symmetrically in the electron reflection portion, so that it is advantageous to keep the inclination angle symmetrical.

9 is a view for explaining a repeller structure for an ion implanter according to the present invention, in which electrons pushed out from a repeller move to a central portion of an arc chamber. Referring to Fig. 9, a repeller projection 303b is formed in the electron reflection portion 303c of the repeller 303. As shown in Fig. At this time, the radius of the electron reflecting portion 303c is R, and the repeller projecting portion 303b is formed in a ring shape having a height h and a width a, separated from the end of the electron reflecting portion 303c by b. When the repeller projecting portion is formed, the electric field formed at the front surface of the electron reflecting portion is formed similarly to the concave form of the repeller, and as a result, the electrons are pushed to the center of the arc chamber. At this time, the formation position, height and width of the repeller projecting portion are variables for changing the ion generation efficiency. (L = b + 1 / 2a), which is the distance from the tip of the electron reflection portion to the repeller projection portion, is 1/2 of R, which is the radius of the electron reflection portion when the distance between the cathode and the repeller is 85 mm to 91 mm R to 0.6R from the end of the electron reflection portion. If the position of the repeller projection is less than 0.1R, the effect of pushing the electrons to the center of the arc chamber is insignificant. If the repeller projection exceeds 0.6R, the electrons outside the electron reflector are diffused to the outside, Is canceled out. The height h of the repeller projecting portion is preferably 0.3R to 0.5R of R, which is the radius of the electron reflecting portion. If the height of the protruding portion of the repeller is less than 0.3R, the effect of pushing the electrons to the center of the arc chamber is insignificant. If the height exceeds 0.5R, the deposited material peeled off from the electron reflection portion can be seated on the protruding portion of the repeller. Further, the width (a) of the repeller projecting portion is preferably 0.1R to 0.3R of R, which is the radius of the electron reflecting portion. If the width of the protruding portion of the repeller is less than 0.1R, the effect of pushing the electrons to the center of the arc chamber is insignificant. If the width exceeds 0.3R, the protruded electrons in the central region of the electron reflection portion converge to an excessively close position, .

Hereinafter, the present invention will be described with reference to Examples.

EXPERIMENTAL EXAMPLE 1 (Measurement of Size of Peeled Deposition)

In a tungsten arc chamber body (105.6 mm in length, 31.7 mm in width, 39.6 mm in width), a cathode having a radius of 10.85 mm was provided on one side of the inside of the arc chamber, and a repeller having a radius of 12.7 mm was provided on the opposite side. Ionization process was performed while BF3 gas was introduced. The ionization process was carried out for an average of 300 hours to collect the deposited material from the 100 arc chambers having a periodic maintenance cycle. Since the peeled deposition was irregular, the longest length was judged as the size of the peeled deposition. Table 1 below summarizes the size of peeled deposition collected from 100 arc chambers by range. Referring to Table 1, a total of 99% of the deposits had a size of less than 8 mm.

Deposition Size 1 to 2 mm 2 ~ 3mm 3 to 4 mm 4 to 5 mm 5 ~ 6mm 6 to 7 mm 7 ~ 8mm 8 to 9 mm 9 ~ 10mm Greater than 10mm Count 13 19 21 26 29 31 One 0 0 0

When the distance between the protruding portion of the repeller and the lower portion of the arc chamber is in the range of 8 to 16 mm, the gap between the protruding portion of the repeller of the present invention and the lower portion of the arc chamber is derived. The size of the deposited material is small, which makes it difficult to cause a short circuit between the repeller and the arc chamber. The upper limit of the gap between the repeller and the bottom of the arc chamber was determined considering ion production efficiency.

Example 1

A cathode having a radius of 10.85 mm was installed on one side of an arc chamber body (length 105.64 mm, height 31.72 mm, width 39.62 mm) made of tungsten, and a repeller having a radius of 12.7 mm was installed on the opposite side to manufacture an arc chamber Respectively. The repeller formed a protrusion on the surface of the electron reflex part. The gap between the tip of the electron reflex part of the refeller and the arc chamber wall was 7.5 mm, the width of the repeller projection was 3 mm and the height was 5 mm, The distance apart from the outer edge was 3.8 mm (a = 3 mm, b = 3.8 mm, h = 5 mm in FIG. 9)

Example 2

The height of the repeller projection was 2.5 mm and the distance that the repeller projection was spaced from the outer periphery of the electron reflection portion was 3.8 mm (a = 3 mm, b = 3.8 mm, h = 2.5 mm in Fig. 9) An arc chamber was produced.

Example 3

The height of the repeller projection was 6 mm and the distance that the repeller projection was spaced from the outer periphery of the electron reflection portion was 3.8 mm (a = 3 mm, b = 3.8 mm, h = 7.6 mm in Fig. 9) The same arc chamber was prepared.

Example 4

The height of the protruding portion of the repeller was 4 mm and the distance that the protruding portion of the repeller was spaced from the outer portion of the electron reflection portion was 0.6 mm (a = 3 mm, b = 0.6 mm, h = 4 mm in FIG. 9) Arc chamber.

Example 5

The height of the repeller projecting portion was 4 mm and the distance that the repeller projecting portion was spaced from the outer portion of the electron reflection portion was 9 mm (a = 3 mm, b = 9 mm, h = 4 mm in Fig. 9) Chamber.

Comparative Example

An arc chamber was produced in the same manner as in Example 1, except that the repeller projection was not formed.

Experimental Example 2 (Measurement of beam current)

Beam current (unit: mA) was measured to compare the generation efficiency of ions by operating the arc chambers of the examples and comparative examples. At this time, argon gas was used and the pressure was 2.5 torr. The voltage supplied to the arc chamber was supplied at 80V, the current supplied to the filament was 160A, and the voltage supplied to the cathode and the refeller was 600V. The measured beam currents are shown in Table 2 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example Beam current 22.3mA 19.8mA 19.3mA 21.7 mA 20.1mA 16.8mA

Referring to Table 1, it was confirmed that the ion generation efficiency of the Examples was higher than that of the Comparative Examples, and in particular, the beam current was the largest in Example 1.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Therefore, the embodiments described in the present invention are not intended to limit the scope of the present invention but to limit the scope of the present invention. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: arc chamber 101: filament
102: cathode 103: repeller
104: chamber wall 104a: chamber upper wall
104b: chamber lower wall 105: ion extraction section
106: gas injection part 200: deposition material
200a: upper deposition material 200b: ripper deposition material
200c: Lower deposition material 303: Repeller
303a: Repeller retaining portion 303b: Repeller protruding portion
303c: electron reflecting portion 304a: chamber upper wall
304b: chamber lower wall

Claims (8)

1. A refeller for mounting a cathode in an arc chamber for an ion implanter of a tungsten material, which is opposed to a cathode and pushes out electrons emitted from the cathode,
A repeller fixing unit for fixing the repeller to one side of the arc chamber of the tungsten material;
An electron reflecting portion connected to the repeller fixing portion and having a surface facing the cathode exposed; And
And the radius of the electron reflecting portion is R so as to protrude in the direction of the cathode from the electron reflecting portion so as to prevent electrical short between the repeller and the arc chamber due to deposits deposited on the surface of the repeller or the chamber wall, And a repeller protrusion having a height of about 0.5R. The method according to claim 1,
And the repeller projecting portion is spaced apart from the one end of the electron reflecting portion at a predetermined interval. The method according to claim 1,
Wherein the repeller projecting portion and the lower portion of the arc chamber are spaced apart by an interval of 8 to 16 mm. The method according to claim 1,
Wherein the repeller projecting portion has an inclination angle? 1 in the direction of the center of the electron reflecting portion, and the inclination angle? 1 is 20 to 60 °. The method of claim 4,
Wherein the repeller projecting portion has an inclination angle? In the direction of the outer periphery of the electron reflection portion and the inclination angle? Is in a range of 30 to 70 degrees and is larger than an inclination angle? 1 in the central portion direction of the electron reflection portion Features a repeater. The method according to claim 1,
The electronic reflector of the repeller is circular,
Wherein the repeller projection is protruded with a width of 0.1R to 0.3R of the radius of the electron reflection portion. The method according to claim 1,
The electronic reflector of the repeller is circular,
Wherein when the radius of the electron reflecting portion is R, the repeller projecting portion is formed at a position spaced apart from the outer periphery of the electron reflecting portion by a distance of 0.1R to 0.6R. An arc chamber for an ion implanter comprising the repeller of claim 1.

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