KR20080084339A - Apparatus for clamping cathode of ion sourse - Google Patents

Abstract

An apparatus for clamping a cathode of an ion source is provided to prevent the degradation of clamping force of a cathode fixing shaft and the mis-alignment of a cathode by using a cathode clamp with a clamp screw. An arc chamber(10) has an ionization space. A cathode(20) has a cylindrical shape of which one lateral side is opened at a side of the arc chamber. A cathode fixing shaft(40) is prepared on the other opened side from a cross-sectional center of the cathode. A cathode clamp(50) clamps the cathode fixing shaft at a side of the outside of the cathode by using a clamp screw. A filament(30) is prepared adjacent to a lateral cross-section of the cathode by integrally connecting a pair of leads being inserted into an inner of the cathode. A filament clamp(60) clamps ends of leads of the filament. A spiral line is formed on an outer circumference of the cathode fixing shaft having a part being clamped to the cathode clamp.

Description

Apparatus for clamping cathode of ion sourse

1 is a cross-sectional view schematically showing an ion source in a conventional ion implantation apparatus,

2 is a cross-sectional view schematically showing an ion source of the ion implantation apparatus according to the present invention;

3 is a perspective view illustrating a coupling structure of a cathode fixing shaft according to the present invention;

Figure 4 is an enlarged view of the main portion showing a coupling structure between the cathode fixed shaft and the cathode clamp in accordance with the present invention.

Explanation of symbols on the main parts of the drawings

10: arc chamber

11: gas ionization space

12 gas inlet

13: ion extractor

20: cathode

30: filament

40: cathode fixed shaft

41: screw thread

42: nuts

50: cathode clamp

60: filament clamp

The present invention relates to a cathode clamping device of an ion source, and more particularly, the coupling between the cathode clamping shaft and the cathode clamp, which is the clamping configuration of the cathode, by the clamping screw of the cathode clamp and simultaneously the cathode clamping shaft on both sides of the cathode clamp. The cathode clamping device of the ion source to prevent the process defect due to the high temperature heat transfer from the arc chamber and the positional deformation of the cathode to ensure that the nut is fastened so that the cathode clamp is also clamped by the cathode fixed shaft. It is about.

In general, ion implantation is a method in which impurities are ionized and then accelerated and physically implanted into the wafer. The implantation depth and amount of ions are determined by the acceleration voltage, ion current, and implantation time. End point detection and precise introduction of impurities are possible.

Such an ion implantation device is called an ion implantation device, and the ion implantation process not only controls precise dice of implanted ions and precise scanning concentrations of implanted ions, but also the side of ion implants generated in dice. The spread is very small compared to the diffusion process has been widely applied in the process of manufacturing a semiconductor that requires high precision.

The ion implantation apparatus usually causes an ion source to generate ions by colliding with an ion gas and hot electrons, a mass spectrometer which extracts only ions necessary for the process among the generated ions, and accelerates the extracted ions. And an ion accelerator for high energy, and a process chamber for implanting ions with high energy onto a desired wafer.

In this case, the ions generated from the ion source are supplied to the process chamber via the mass spectrometer and the ion accelerator, and a beam line is installed between the ion source and the process chamber so that ions can be supplied. Spin disk unit (Spin) to allow the wafer to be seated while selectively rotating or rotating in accordance with the process proceeds in front of the beam discharge port with the beam discharge port from which the ion beam is discharged so that the ion beam supplied along the beam line can be injected onto the desired wafer disk unit) is being installed.

On the other hand, the ion source for generating ions is composed of a configuration including an arc chamber (arc chamber), a gas supply, a cathode (cathode) and a filament (filament).

1 is a schematic cross-sectional view of an ion source in a conventional ion implantation apparatus.

The arc chamber 100 of the ion source as shown is configured to have a gas ionization space 110 of a predetermined size therein, and the gas supply unit for supplying gas to the gas ionization space 110 at this time is a solid state source It consists of a configuration including a vaporizer for vaporizing to form a gas capable of ionization.

The cathode 200 has a cylindrical configuration extending into the arc chamber 100 through the hole 120 at one side of the arc chamber 100, and the front end is blocked, the rear end is open, and the front end is Is disposed inside the arc chamber 100.

The filament 300 is disposed inside the cathode 200 and emits electrons toward the front end of the cathode 200.

When the cathode 200 is heated by ion bombardment, the cathode 200 emits electrons to the gas ionization space 110, and the electrons emitted to the cathode 200 are transferred to the arc chamber 100 through the gas supply hole 120. An ion plasma is formed while colliding with the gas molecules supplied into the inside.

Ions in the ion plasma are extracted through the ion extraction port 130 formed in the arc chamber 100 to form the ion beam.

In this case, the filament 300 includes an electron emission unit for emitting electrons and a pair of leads extending in the axial direction of the cathode 200, and is fixed by the pair of filament clamps 310.

The cathode 200 has a cathode fixed shaft 210 is formed from the center portion of the front end, the cathode fixed shaft 210 is fixed by the cathode clamp 220 so that the end is extended to the outside of the cathode 200 I am trying to.

However, the gas ionization space 110 of the arc chamber 100 is severely degraded as the temperature of the ion beam is raised to about 2000 ° C. during the process, and the high temperature heat in the gas ionization space 110 causes the cathode 200 to be deteriorated. It is transmitted to the cathode fixed shaft 210 and the cathode clamp 220 to be connected to each other through.

The high temperature heat transmitted to the cathode clamp 220 causes thermal deformation of the cathode clamp 220 to relax the portion clamping the cathode fixing shaft 210.

Therefore, as the clamping force of the cathode fixing shaft 210 by the cathode clamp 220 is lowered, the cathode 200 is struck downward by its own weight, thereby making the alignment position poor.

Since the misalignment of the cathode 200 causes an electron emission error through the cathode 200, not only the ion source generation efficiency is lowered, but also a serious problem that causes a process defect occurs.

Accordingly, the present invention has been invented to solve the above-mentioned problems of the prior art, and an object of the present invention is to ensure that the cathode clamping force can be stably maintained even when high temperature heat is transferred from the cathode by generation of an ion beam. It is to provide a clamping device.

It is another object of the present invention to provide a cathode clamping device of an ion source to improve the efficiency of ion generation and process performance by preventing the cathode misalignment in advance.

In order to achieve the above object, the present invention provides an arc chamber having an ionization space; A cylindrical cathode having one side open at one side of the arc chamber; A cathode fixed shaft provided on the other side opened from the center of one end surface of the cathode; A cathode clamp for clamping the cathode fixed shaft using a clamp screw at one side of the cathode; A filament provided in close proximity to a side end surface of the cathode such that a pair of leads inserted into the cathode are integrally connected to each other; A filament clamp for clamping ends of the leads of the filament; The cathode fixing shaft is a screw thread is formed on the outer peripheral surface of the end clamped to the cathode clamp, and a pair of nuts are fastened on both sides of the cathode clamp to be coupled to the cathode clamp.

In the above configuration, the cathode is made of molybdenum or molybdenum alloy, and in particular, the insertion end side side cross-section corresponding to the open face of the cathode is preferably made of tungsten or tungsten alloy for electron emission into the gas ionization space.

The cathode fixed shaft is made of tungsten, and the nut fastened to the cathode fixed shaft is more preferably made of a carbon-based material having heat resistance.

More preferably, two nuts are axially coupled to both sides of the cathode fixed shaft based on the cathode clamp.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view schematically showing an ion source of the ion implantation apparatus according to the present invention.

The ion source is a portion that generates ions as described above, and the ion source is largely composed of the arc chamber 10, the cathode 20, and the filament 30.

The arc chamber 10 has a gas ionization space 11 therein, and a gas supply port 12 and an ion extraction port 13 are formed in the upper and lower portions, respectively.

The arc chamber 10 allows gas molecules to flow through the gas supply port 12 to form an ion plasma in the gas ionization space 11, and the ions inside the ion plasma are transferred to the arc chamber 10 to form an ion beam. It is to be extracted through the ion extraction port 13 formed.

Usually, the arc chamber 10 is made to have a hexahedral shape with a larger length laterally.

The cathode 20 emits electrons into the gas ionization space 11 of the arc chamber 10 to form an ion plasma by contact with gas molecules introduced into the gas ionization space 11.

The cathode 20 has a cylindrical shape open to only one side, and is inserted from one side of the arc chamber 10 with the open face facing outward.

The cathode 20 may be made of molybdenum or molybdenum alloy, and in particular, the insertion end side side surface corresponding to the open surface may be made of tungsten or tungsten alloy for electron emission into the gas ionization space 11.

The filament 30 is provided to allow electrons to be emitted to the gas ionization space 11 through the cathode 20.

The filament 30 is made of tungsten or tungsten alloy, and a pair of leads inserted therein through an open portion of the cathode 20 emits electrons toward the side end side of the insertion end of the cathode 20. The connecting end connecting the pair of leads integrally is provided in close proximity.

At this time, the connection end to which the pair of leads is connected is a site that emits electrons.

In the above configuration, the cathode 20 and the filament 30 are respectively fixed by the clamps 50 and 60.

In particular, the cathode fixing shaft 40 is integrally coupled to the cathode 20 in order to fix the cathode 20 by the cathode clamp 50.

One end of the cathode fixing shaft 40 is coupled to the side end surface of the insertion end of the cathode 20, and the other end thereof is drawn out in the axial direction of the cathode 20 to be fixed by the cathode clamp 50, and the cathode is fixed. The axis 40 forms the ground line of the cathode 20.

On the other hand, the cathode fixing shaft 40 fixed to the cathode clamp 50 allows the threaded line 41 to be formed on the outer circumferential surface, and the cathode clamp 50 on the outer circumferential surface on which the threaded line 41 is formed based on the cathode clamp 50. The most prominent feature of the present invention is that the nut 42 is screwed to be in close contact with both sides.

3 is a perspective view showing a coupling structure of a cathode fixing shaft according to the present invention.

As shown in the drawing, a screw thread 41 is formed on the outer circumferential surface of the cathode fixed shaft 40 extending from one end inserted into the cathode 20 so as to extend outwardly, and two or more along the screw thread 41 are formed. Let the nut 42 screw in.

The nut 42 is most preferably used as a carbon material so that deformation or damage can be prevented even by high temperature heat transmitted through the cathode fixing shaft 40.

In addition, the nut 42 is more preferably such that the lock nut 43 is coupled to the outside in order to prevent a decrease in adhesion force due to loosening of the screw with the cathode clamp 50.

The cathode clamp 50 is coupled to the cathode fixing shaft 40 through the upper portion, and the hole through which the cathode fixing shaft 40 penetrates is cut in the vertical direction so that the cathode clamp 50 passes from the lower side of the cathode clamp 50 to one side. The clamping screw 51, which is coupled, allows the cathode fixed shaft 40 to be firmly fixed.

The filament 30 inserted into the cathode 20 together with the cathode fixing shaft 40 fixed to the cathode 20 allows the pair of leads to be fixed by the filament clamp 60, respectively.

The fixing of the filament 30 by the filament clamp 60 may cause the cathode fixing shaft 40 to be formed similarly to the fixing configuration by the cathode clamp 50, and alternatively at each filament clamp 60 It may be fixed in various ways, but may be formed as a conventional clamping structure.

Therefore, each lead of the filament 30 is provided in parallel with the cathode fixing shaft 40 while extending further rearward than the cathode fixing shaft 40 so that the filament clamp 60 is not interfered with the cathode clamp 50. do.

In the drawing, reference numeral 70 denotes a repeller provided to repel electrons emitted into the gas ionization space 11.

The assembly structure and operation of the cathode fixed shaft 40 and the cathode clamp 50 according to the present invention configured as described above will be described in more detail as follows.

The ion source according to the present invention is a site provided to generate ions in the ion implantation apparatus.

That is, the ionic gas flows into the gas ionization space 11 from the arc chamber 10 through the gas supply port 12, and at the same time, power is applied to the filament 30 to electrons from the cathode 20 to the gas ionization space 11. When emitted, the ion plasma is generated by the reaction with the ion gas.

The ion plasma generated in the gas ionization space 11 is extracted through the ion extraction port 13.

When the ion plasma is formed, the cathode 20 is heated to a temperature of about 2000 ° C., and the cathode fixed shaft 40 is heated through the cathode 20, and the cathode fixed shaft 40 is applied to the cathode clamp 50. It is fixed by the heat transfer structure that eventually heats the cathode clamp 50.

At this time, the cathode fixing shaft 40 is fixed to the cathode clamp 50 and at the same time to ensure that the cathode clamp 50 is firmly coupled by a nut 42 screwed to the cathode fixing shaft 40.

4 is an enlarged view illustrating main parts of a coupling structure between a cathode fixed shaft and a cathode clamp according to the present invention;

As shown in the drawing, the cathode fixing shaft 40 is inserted horizontally through the upper portion of the cathode clamp 50 while tightening the clamping screw 51 on one side of the cathode clamp 50 so as to firmly clamp the cathode fixing shaft ( 40 also has nuts 42 on both sides of the portion fixed to the cathode clamp 50 so that these nuts 42 are screwed to the cathode clamp 50 side closely to closely contact the cathode clamp 50. The cathode clamp 50 is also clamped by the cathode fixing shaft 40.

In more detail, before coupling to the cathode clamp 50, first, one nut 42 is screwed to the cathode fixing shaft 40, and the cathode fixing shaft 40 is coupled to the cathode clamp 50. .

The cathode fixing shaft 40 was clamped by operating the clamping screw 51 while the cathode fixing shaft 40 was fixed to the cathode clamp 50 and then pulled out to the outside through the cathode clamp 50. The nut 42 is screwed to the lead end of the 40.

The cathode clamping shaft 40 is firmly fixed to the cathode clamp 50, and the nuts 42 screwed to both sides of the cathode clamp 50 of the cathode fixing shaft 40 in opposite directions are rotated in the opposite direction. Move to (50) side.

When the nuts 42 on both sides are moved from the cathode fixing shaft 40 to be in close contact with the cathode clamp 50, the cathode clamp 50 is firmly attached to the cathode fixing shaft 40 between the nuts 42 on both sides. Is clamped.

As described above, the present invention is further enhanced by mutual coupling force compared to when the cathode fixing shaft 40 and the cathode clamp 50 are clamped to each other, compared to when the cathode fixing shaft 40 is fixed only by the cathode clamp 50. .

In this way, the cathode fixed shaft 40 and the cathode clamp 50 are able to clamp each other, so that the cathode clamp (by the high temperature heat transmitted through the cathode 20 and the cathode fixed shaft 40 by ion generation during the process). 50 may be thermally deformed, which may lower the clamping force of the cathode fixing shaft 40, but as described above, the cathode clamp 50 may be connected to both nuts 42 screwed to the cathode fixing shaft 40. Since the clamping force of the cathode clamp 50 is lowered because it is firmly fixed by the surface contact, the cathode clamp 50 is strongly fixed by the nut 42 on the cathode fixing shaft 40, so The clamping force of the cathode fixing shaft 40 due to thermal deformation can be prevented from being lowered.

If the mutual coupling force between the cathode fixed shaft 40 and the cathode clamp 50 is mutually reinforced as in the present invention, the cathode 20 and the cathode fixed shaft 40 and the cathode clamp 50 perform a process of generating ions. Even if it is deteriorated by high temperature heat, the clamping state between the cathode fixed shaft 40 and the cathode clamp 50 can be stably maintained, thereby providing a more stable process performance.

On the other hand, while many matters have been described in detail in the above description, they should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention.

Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, according to the present invention, the outer peripheral surface includes a portion clamped to the cathode clamp of the cathode fixed shaft provided to support the cathode and form a ground line, and a screw thread is formed on the outer circumferential surface to be clamped to the cathode clamp from both sides of the cathode clamp. Improved coupling structure of cathode fixing shaft and cathode clamp so that nuts are screwed to cathode fixing shaft to tighten the cathode clamp on both sides, thereby reducing clamping force of cathode fixing shaft due to high temperature during process and poor alignment of cathode There is an advantage to prevent.

Therefore, the present invention has a very useful effect of stabilizing the emission of electrons through the cathode to stably perform the ion generation and ion implantation process in the arc chamber.

Claims (6)

An arc chamber having an ionization space; A cylindrical cathode having one side open at one side of the arc chamber; A cathode fixed shaft provided on the other side opened from the center of one end surface of the cathode; A cathode clamp for clamping the cathode fixed shaft using a clamp screw at one side of the cathode; A filament provided in close proximity to a side end surface of the cathode such that a pair of leads inserted into the cathode are integrally connected to each other; A filament clamp for clamping ends of the leads of the filament; The cathode fixed shaft is, An ion source is formed with an outer circumferential surface including a portion clamped to the cathode clamp, and an ion source for screwing a pair of nuts on both sides of the cathode clamp to be in close contact with the cathode clamp to clamp the cathode clamp. Cathode clamping device. 2. The cathode clamping device of claim 1 wherein the cathode is made of molybdenum or molybdenum alloy material. 3. The cathode clamping device of claim 2, wherein the cathode is made of a tungsten or tungsten alloy material such that the insertion end side side surface corresponding to the open surface is for electron emission into the gas ionization space. The cathode clamping device of claim 1, wherein the cathode fixed shaft is made of a tungsten material. The cathode clamping device of claim 1, wherein the nut fastened to the cathode fixed shaft is made of a carbon material having heat resistance. The cathode clamping device of claim 1, wherein two nuts are coupled to both sides of the cathode fixing shaft based on the cathode clamp.

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