JP6051983B2 - Arc plasma deposition system - Google Patents

Description

  The present invention relates to an arc plasma film forming apparatus for forming a carbon film by forming an arc plasma.

  According to the carbon film manufacturing apparatus using the method called the filtered arc deposition (FAD) method and the filtered cathodic vacuum arc (FCVA) method, the arc discharge is continuously excited on the surface of the carbon target. Then, ionized carbon charged particles are guided to the substrate surface to form a carbon film (see, for example, Non-Patent Document 1). This carbon film is particularly called a tetrahedral amorphous carbon (taC) film.

  In the above method, in order to prevent carbon fine particles called droplets generated during arc discharge from adhering to the film formation surface, the arc discharge location and the film formation surface of the substrate are not connected linearly. Has been. Thereby, the incidence to the film-forming surface of the droplet discharge | released linearly from the carbon target surface is suppressed. As a specific example, a structure in which a bent tube having a bent portion is connected between the carbon target and the film formation surface is employed. Similarly, the particles (macroparticles) generated by the peeling of the carbon thin film deposited inside the bent tube must be prevented from adhering to the film formation surface.

  In a structure using a bent tube, a magnetic field is used to efficiently guide carbon ions to the film formation surface. In other words, a magnetic field is formed along the bent tube to perform plasma transport. The carbon film is formed using carbon ions in plasma as a raw material. Droplets and macroparticles are basically not charged particles and are not affected by a magnetic field, so they are removed at the stage of plasma transport along the bent tube. That is, the bent tube functions as a filter.

Hiroshi Takikawa et al., “Development of bent tube vacuum arc deposition (FAD) equipment”, [online], 2003, Toyohashi University of Technology, [November 6, 2012 search], Internet <URL: http: // arc.ee.tut.ac.jp/ ＞

  As mentioned above, many primary droplets and macroparticles are removed by the bent tube. However, the macro particles that are secondarily generated from the droplets colliding with the inner wall of the bent tube may reach the film formation surface after a plurality of collisions with the bent tube. In addition, these electrically neutral particles are charged in plasma and may behave similarly to charged particles.

  In order to suppress secondary generated macro particles, it is particularly effective to keep the inside of the bent tube clean. However, frequently opening the chamber to the atmosphere and maintaining the inside for that purpose hinders efficient operation of the film forming apparatus.

  In view of the above problems, an object of the present invention is to provide an arc plasma film forming apparatus that realizes a high operating rate and that can easily perform maintenance work for removing droplets and macro particles.

According to one aspect of the present invention, there is provided an arc plasma film forming apparatus for generating an arc plasma containing carbon ions and forming a thin film containing carbon as a main component on a substrate to be processed. A storage chamber to be stored; (b) a discharge chamber in which a carbon target for film formation is disposed; (c) a bent tube having a bent portion connecting the storage chamber and the discharge chamber; and (d) facing each other. A plasma generating unit that generates glow discharge by a multi-hollow cathode electrode in which through holes each having an opening are formed in the main surface, and generates plasma for carbon ashing by glow discharge in at least one of the storage chamber and the bent tube An arc for removing carbon film and carbon dust generated in the storage chamber and the bent tube by reacting with plasma for carbon ashing Plasma deposition apparatus is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the arc plasma film-forming apparatus which implement | achieves a high operation rate and can perform the maintenance operation | work which removes a droplet and a macro particle easily can be provided.

It is a schematic diagram which shows the structure of the arc plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the method of removing a droplet and a macro particle with the arc plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram for demonstrating the method of removing a droplet and a macro particle with the arc plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the example of the cathode electrode used for the arc plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a table | surface which shows the cleaning result in the arc plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a graph which shows the cleaning result in the arc plasma film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the arc plasma film-forming apparatus which concerns on the modification of the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the arc plasma film-forming apparatus which concerns on the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic. Further, the embodiment described below exemplifies an apparatus and a method for embodying the technical idea of the present invention, and the embodiment of the present invention has the following structure and arrangement of components. It is not something specific. The embodiment of the present invention can be variously modified within the scope of the claims.

(First embodiment)
The arc plasma film forming apparatus 1 shown in FIG. 1 according to the first embodiment of the present invention generates an arc plasma 200 containing carbon ions by arc discharge, and treats a thin film mainly composed of carbon as a substrate 100 to be processed. This is a film forming apparatus employing the FAD method formed on the top. The carbon target 600 for film formation is exposed to the arc plasma 200 in order to form a desired thin film on the substrate 100.

  As shown in FIG. 1, the arc plasma film forming apparatus 1 connects the storage chamber 10 in which the substrate 100 is stored, the discharge chamber 20 in which the carbon target 600 is disposed, and the storage chamber 10 and the discharge chamber 20. The main component is a gas that has an effect on carbon ashing (etching) in at least one of the bent tube 30 having the bent portion, the induction coil 40 disposed along the bent tube 30, and the storage chamber 10 and the bent tube 30. And a plasma generation unit 50 for generating plasma for carbon ashing. In the example illustrated in FIG. 1, the plasma generation unit 50 is disposed in the bending tube 30. In addition, the substrate 100 is disposed on the stage 12 in the storage chamber 10.

  The induction coil 40 guides the arc plasma 200 generated on the surface of the carbon target 600 by the arc discharge excited in the discharge chamber 20 from the discharge chamber 20 to the main surface of the substrate 100 through the bent tube 30. To form a magnetic field.

  In the example shown in FIG. 1, a plurality of carbon targets 600 are stored in a target storage chamber 60 connected to the discharge chamber 20, and one of the carbon targets 600 is disposed so as to be exposed in the discharge chamber 20. ing. For example, a columnar carbon target 600 is exposed in the discharge chamber 20, whereby the surface of the carbon target 600 is exposed to the arc plasma 200.

  The carbon target 600 includes a target material 601 that is a raw material of carbon to be deposited on the substrate 100 and a target holder 602 in which the target material 601 is stored.

  In the arc plasma film forming apparatus 1, arc plasma 200 containing carbon ions is generated by arc discharge generated using the carbon target 600 exposed in the discharge chamber 20 as a cathode. The carbon ions are guided from the discharge chamber 20 to the surface of the substrate 100 in the storage chamber 10 through the bent tube 30, and a carbon film is formed on the substrate 100.

  Specifically, an arc plasma 200 containing carbon ions that are positive ions is generated by a magnetic field formed by one or more induction coils 40 arranged along the bent tube 30, as shown in FIG. 1. And is induced on the substrate 100 from the discharge chamber 20. The induction coil 40 is, for example, an electromagnetic induction coil that is excited by a supplied current, and is an annular coil in which the bent tube 30 is disposed at the center. The strength of the magnetic field formed by the induction coil 40 is controlled according to the magnitude of the current supplied by the exciting current source (not shown). The trajectory of the plasma transport is controlled by controlling the current flowing through the induction coil 40, and the arc plasma 200 is transported in the bent tube 30 by the bent tube.

  As already mentioned, carbon droplets are generated from the carbon target by arc discharge. However, since the droplets are not charged particles, they fly linearly without being affected by the magnetic field. For this reason, it cannot pass through the bent tube 30 having the bent portion and reach the storage chamber 10, and remains inside the bent tube 30. In this way, the droplets are removed (filtered), and a taC film having no droplets is formed on the substrate 100.

  However, in the long-term use, the carbon film and the carbon powder are deposited on the inner walls of the storage chamber 10 and the bent tube 30 and become a new source of macro particles.

  In contrast, in the arc plasma film forming apparatus 1 shown in FIG. 1, a plasma generating unit 50 that removes a carbon film or the like deposited in the storage chamber 10 or the bent tube 30 is disposed in the bent tube 30. In the example shown in FIG. 1, the plasma generation unit 50 is disposed at the bent portion of the bent tube 30.

Specifically, when the plasma 300 containing oxygen as a main component is used for carbon ashing, the plasma generator 50 generates glow discharge in the bent tube 30 using the cathode electrode 52 disposed in the bent tube 30. Let The macro particles deposited on the inner wall of the storage chamber 10 and the bent tube 30 are removed by the carbon ashing plasma 300 shown in FIG. 2 generated by the glow discharge. That is, carbon dioxide (CO ₂ ) is generated by reacting carbon (C) with macro particles and oxygen (O). The generated carbon dioxide is discharged to the outside of the arc plasma film forming apparatus 1 from, for example, an exhaust port 11 disposed in the storage chamber 10.

When using the plasma 300 with nitrogen (N ₂ ) as a correction component, the nitrogen plasma generated by the plasma generation unit 50 etches (removes) the macro particles that have accumulated on the inner wall and the like, and the etched carbon particles are discharged from the exhaust port. 11 is discharged outside the apparatus.

  The plasma generator 50 includes an anode electrode 51, a cathode electrode 52, an AC power supply 53, and a gas introduction mechanism 54. The anode electrode 51 and the cathode electrode 52 have, for example, a comb shape as shown in FIGS. 1 and 2, and are alternately arranged so that the tooth portions of each comb face each other.

At the time of cleaning, as shown in FIG. 2, a cleaning gas 500 containing a gas effective for ashing (and etching) is introduced into the bent tube 30 from the gas introduction mechanism 54 of the plasma generation unit 50. As the cleaning gas 500, for example, any one of O ₂ + Ar, O ₂ , N ₂ + Ar, N ₂ , and O ₂ + N ₂ + Ar is used.

  Then, glow discharge is caused by supplying predetermined AC power between the anode electrode 51 and the cathode electrode 52 by the AC power source 53. The droplets and macro particles existing in the bent tube 30 and the storage chamber 10 are removed (ashed) by radicals and ions generated by glow discharge. As described above, the arc plasma film forming apparatus 1 can perform self-cleaning that does not require opening the storage chamber 10 to the atmosphere.

  At the time of cleaning, the induction coil 40 may form a magnetic field that guides the plasma 300 from the bent tube 30 to the storage chamber 10. Thereby, the plasma 300 can be guided into the bent tube 30 and the storage chamber 10, and the particles in the storage chamber 10 can be efficiently removed.

  Further, the induction coil 40 forms a magnetic field opposite to the case of inducing the arc plasma 200 at the time of film formation, and the carbon ashing plasma 300 is induced toward the discharge chamber 20 as shown in FIG. Good. Thereby, the inside of the bent tube 30 between the cathode electrode 52 and the discharge chamber 20 can be efficiently cleaned.

  By forming the magnetic field for inducing the plasma 300 by the induction coil 40 in the bent tube 30 as described above, the entire bent tube 30 and the storage chamber 10 can be thoroughly cleaned and the cleaning time can be shortened.

  As the cathode electrode 52 of the plasma generating unit 50, a multi-hollow cathode electrode in which a plurality of through holes having openings on the cathode main surface facing the anode electrode 51 can be used. For example, a multi-hollow cathode electrode having a comb structure in which a large number of through holes are formed in a comb tooth portion is used.

  In the multi-hollow cathode electrode, the plasma generation inside the through hole is a hollow cathode discharge. In this hollow cathode discharge, electrons are confined inside the through hole and have kinetic energy, which is a high-density electron space. A high density plasma region is formed in the through hole. As shown in FIG. 4, the multi-hollow cathode electrode has through holes 520 each having openings on the main surfaces 521 and 522 of the cathode electrode 52, so that the hollow cathode discharge generated in each of the through holes 520 is generated. In addition, uniform multi-hollow discharge is obtained on both sides of the cathode electrode 52. Since the space in which the high-density plasma is generated is a through hole, the continuity of the plasma is ensured between the two main surfaces in the multi-hollow cathode electrode. For this reason, a uniform high electron density electric field can be easily generated on both surfaces of the cathode electrode 52. Thus, since the multi-hollow cathode electrode can easily generate high-density plasma, it is suitable for this application, and thus droplets and microparticles can be effectively removed.

  Below, the evaluation example of the result of having implemented the cleaning which removes a droplet in the arc plasma film-forming apparatus 1 is shown. The evaluation was performed according to the following procedure.

  First, a carbon film having a sufficient film thickness was formed on the substrate 100 by the arc plasma film forming apparatus 1. Next, the storage chamber 10 was opened to the atmosphere, and the amount of particles in the central region of the bent portion of the bent tube 30 was measured using an air particle counter. The measurement amount here is “measurement amount P1 before cleaning”.

  Thereafter, the inside of the storage chamber 10 was evacuated and cleaning was performed using the plasma generation unit 50. Specifically, the droplet removal process of the bent tube 30 was performed using a mixed gas of Ar gas and oxygen gas. In the removal process, glow discharge was performed three times for 10 minutes under the conditions of an Ar gas flow rate of 400 sccm, an oxygen gas flow rate of 200 sccm, a pressure of 70 Pa, and a discharge power of 400 W.

  After the removal process, the storage chamber 10 was opened to the atmosphere, and the amount of particles in the central region of the bent portion of the bent tube 30 was measured. The measurement amount here is “measurement amount P2 after cleaning”.

  5 and 6 show the measurement amount P1 before cleaning and the measurement amount P2 after cleaning for each particle size (particle diameter). Symbols A to E in FIG. 6 indicate measurement amounts when the particle sizes are 0.3 μm, 0.5 μm, 1 μm, 2 μm, and 5 μm, respectively.

  As shown in FIGS. 5 and 6, the amount of particles having a particle size of 0.3 μm to 5 μm could be reduced to 4 to 8% by the removal process. Therefore, the effect of cleaning the bent tube 30 by the arc plasma film forming apparatus 1 was confirmed.

  As described above, in the arc plasma film-forming apparatus 1 according to the first embodiment of the present invention, by generating the plasma for carbon ashing in the storage chamber 10 and the bent tube 30, the storage chamber 10 is formed. The droplets and particles deposited inside the arc plasma film forming apparatus 1 can be easily removed without opening to the atmosphere. As a result, it is possible to provide the arc plasma film forming apparatus 1 that realizes a high operating rate and that can easily perform maintenance work for removing droplets.

<Modification>
FIG. 7 shows an arc plasma film forming apparatus 1 according to a modification of the first embodiment of the present invention. In the arc plasma film forming apparatus 1 shown in FIG. 7, the plasma generating unit 50 is disposed in the storage chamber 10. That is, the cathode electrode 52 of the plasma generating unit 50 is disposed in the storage chamber 10, and the storage chamber 10 and the bent tube 30 are cleaned by the carbon ashing plasma 300 formed in the storage chamber 10.

  Note that a magnetic field opposite to the direction in which the arc plasma 200 is induced by the induction coil 40 is formed in the bent tube 30, and the plasma 300 can be guided from the storage chamber 10 toward the bent tube 30. Thereby, the inside of the bending tube 30 can be cleaned efficiently.

(Second Embodiment)
FIG. 1 shows an example in which the storage chamber 10 and the bent tube 30 are integrated. However, the present invention is also applicable to the arc plasma film forming apparatus 1 in which the storage chamber 10 and the bent tube 30 can be separated.

  FIG. 8 shows an example of the arc plasma film forming apparatus 1 when the storage chamber 10 is separated. In other words, the connection portion between the bent tube 30 and the storage chamber 10 is blocked by the blocking mechanism 31. Further, a discharge mechanism 32 is disposed on the bent tube 30. Other configurations are the same as those of the first embodiment shown in FIG. The plasma generating unit 50 is installed in the bent tube 30.

  In the arc plasma film forming apparatus 1 according to the second embodiment shown in FIG. 8, droplets and the like deposited on the inner wall of the bent tube 30 are removed by the plasma 300 formed in the bent tube 30. The product generated in the bent tube 30 by the reaction between the droplet and the plasma 300 is discharged from the discharge mechanism 32 to the outside of the arc plasma film forming apparatus 1. Others are substantially the same as those in the first embodiment, and redundant description is omitted. For example, also in the arc plasma film forming apparatus 1 shown in FIG. 8, the magnetic field that induces the plasma 300 during cleaning may be formed by the induction coil 40.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above description, the plasma 300 is generated by glow discharge. However, the plasma 300 may be generated by other methods. The present invention can also be applied to the arc plasma film forming apparatus 1 that employs a film forming method other than the FAD method.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Arc plasma film-forming apparatus 10 ... Storage chamber 11 ... Exhaust port 12 ... Stage 20 ... Discharge chamber 30 ... Bending pipe 31 ... Shut-off mechanism 32 ... Discharge mechanism 40 ... Inductive coil 50 ... Plasma generating part 51 ... Anode electrode 52 ... Cathode Electrode 53 ... AC power supply 54 ... Gas introduction mechanism 60 ... Target storage chamber 100 ... Substrate 200 ... Arc plasma 300 ... Plasma for carbon ashing 500 ... Cleaning gas 600 ... Carbon target

Claims (7)

An arc plasma film forming apparatus for generating an arc plasma containing carbon ions and forming a thin film mainly composed of carbon on a substrate to be processed,
A storage chamber in which the substrate is stored;
A discharge chamber in which a carbon target for film formation is disposed;
A bent tube having a bent portion connecting the storage chamber and the discharge chamber;
A glow discharge is generated by a multi-hollow cathode electrode in which through holes each having an opening are formed on main surfaces facing each other , and plasma for carbon ashing is generated in at least one of the storage chamber and the bent tube by the glow discharge. An arc plasma film forming apparatus, comprising: a plasma generating unit that generates the carbon film and carbon dust generated in the storage chamber and the bent tube by reacting with the carbon ashing plasma. 2. The plasma ashing unit generates the plasma for carbon ashing from any gas of O ₂ + Ar, O ₂ , N ₂ + Ar, N ₂ , and O ₂ + N ₂ + Ar. Arc plasma deposition system. An induction coil disposed along the bent tube;
It said induction coil, arc plasma deposition apparatus according to a magnetic field that induces a plasma for the carbon ashing to claim 1 or 2, characterized in that formed on the bent pipe. The induction coil forms a magnetic field opposite to the case where the arc plasma formed on the surface of the carbon target is guided from the discharge chamber to the main surface of the substrate through the bent tube, and the carbon ashing is performed. An arc plasma film forming apparatus according to claim 3 , wherein a plasma for use is induced. It said plasma generating portion, the arc plasma film forming apparatus according to any one of claims 1 to 4, characterized in that it is disposed in the bent tube. A blocking mechanism that blocks a connection point between the bent tube and the storage chamber;
A discharge mechanism installed in the bent pipe, and a product generated in the bent pipe due to a reaction between the carbon film and carbon dust and the plasma for carbon ashing is discharged from the discharge mechanism. An arc plasma film forming apparatus according to claim 5 . It said plasma generating portion, the arc plasma film forming apparatus according to any one of claims 1 to 4, characterized in that it is arranged in the storage chamber.

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