JP2015175052A - Film deposition apparatus, plasma gun, and method of manufacturing article with thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition device with a plasma gun that can maintain a discharge for a long period as film deposition particles hardly stick on an electrode in which electrons flow.SOLUTION: A plasma gun 10 is connected to a film deposition chamber 11. The plasma gun 10 includes a cathode 1 which is arranged in order along an axial direction 101, and an anode 5 including a part (electrode 6) projecting toward the film deposition chamber 11. The electrode 6 is so shaped as to project from the anode 5 toward the film deposition chamber 11, so electrons in plasma easily flow in the electrode, which has a high temperature during plasma generation. Consequently, film deposition particles hardly stick on the projecting part (electrode 6), and a discharge can be maintained.

Description

  The present invention relates to a film forming apparatus using a plasma gun.

An apparatus for manufacturing a ferroelectric film using a pressure gradient plasma gun is disclosed in Patent Document 1. The pressure gradient plasma gun can generate and maintain high-density arc discharge plasma inside the chamber. It is disclosed that a Pb (Zr _x Ti _1-x ) O ₃ (PZT) film having excellent dielectric properties can be produced by activating atmospheric gas or material vapor using this arc discharge plasma. Yes.

  Patent Document 2 discloses a configuration in which an anode cover having a collar portion is attached to the anode to prevent deposition of film-forming particles on the inner wall region of the anode through hole.

Japanese Patent No. 4138196 JP 2013-65417 A

  Since the anode of the plasma gun is closest to the chamber (film formation chamber), the surface of the anode on the chamber side is exposed to material vapor flying from an evaporation source or the like in the chamber to form a film. In particular, when a semiconductor or insulator material is formed, a high resistance film often adheres to the anode, and the anode is insulated. As a result, the discharge current becomes unstable, and the discharge suddenly disappears during the generation of the plasma, or the discharge occurs on the atmosphere side of the plasma gun and the plasma gun is damaged. In addition, when the plasma becomes unstable, a thin film having desired characteristics cannot be formed even when the film can be formed, or impurities may be mixed or a different phase may be generated.

  Further, the anode cover having a collar portion described in Patent Document 2 prevents the deposition particles from adhering to the inner wall region of the anode through hole by shielding the deposition particles with the collar portion. Therefore, since the film forming particles adhere to the collar portion, maintenance is required to periodically remove the film forming particles adhering from the collar portion.

  It is an object of the present invention to provide a film forming apparatus using a plasma gun that can prevent a film forming particle from adhering to an electrode into which electrons flow and can maintain a long-term discharge.

  In order to achieve the above object, a film forming apparatus of the present invention is provided with a film forming apparatus having a film forming chamber and a plasma gun connected to the film forming chamber. The plasma gun includes a cathode and an anode including a portion protruding toward the film forming chamber, which are sequentially arranged along the axial direction.

  According to the present invention, electrons in the plasma flow into the protruding portion of the anode, and the protruding portion is maintained at a high temperature. Therefore, the film-forming particles are unlikely to adhere, and the discharge can be maintained for a long time.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the whole structure of the film-forming apparatus of embodiment. Explanatory drawing which shows the cross-sectional structure of the plasma gun of embodiment, and an electron orbit.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of the overall configuration of a film forming apparatus, and FIG. 2 is a cross-sectional view of an example of a plasma gun.

  As shown in FIGS. 1 and 2, the film forming apparatus of the present embodiment includes a film forming chamber 11 and a plasma gun 10 connected to the film forming chamber 11. The plasma gun 10 includes a cathode 1 disposed along the axial direction, and an anode 50 including a portion (6) protruding toward the film forming chamber.

  As described above, since the anode 50 has the portion (6) protruding toward the film forming chamber 11, the electrons contained in the plasma drawn out from the plasma gun 10 into the film forming chamber 11 are protruded ( 6) concentrates and flows into the anode 50. Due to the inflow of electrons, a current flows through the protruding portion (6), and the protruding portion (6) is heated. Thereby, even if the film-forming particles reach the protruding part (6), the film-forming particles are difficult to adhere because of the high temperature, and the whole protruding part (6) is prevented from being covered with the film-forming particles. be able to. Therefore, even if the film-forming particles are an insulator or a semiconductor, at least a part of the protruding portion (6) is kept exposed, and the discharge can be maintained. Further, as the temperature of the protruding portion (6) increases, the electric resistance of the protruding portion (6) decreases, and more electrons easily flow into the protruding portion (6), and the protruding portion (6) ) Can be maintained at a high temperature. Therefore, the film-forming particles are less likely to adhere to the protruding portion (6), and the protruding portion (6) can be prevented from being covered with the film-forming particles.

  The anode 50 may include a portion that protrudes toward the film forming chamber (hereinafter referred to as an electrode 6) and an anode base portion 5 that is disposed closer to the cathode 1 than the electrode 6 and is in contact with the electrode 6. The contact area between the electrode 6 and the anode base 5 is set so that the electrode 6 has a higher temperature than the anode base 5 during plasma generation of the plasma gun. At this time, since the electrode 6 is in contact with the anode base 5, it is almost equipotential with the anode base 5. Therefore, the electrode 6 electrically constitutes the anode 50 together with the anode base 5. Electrons included in the plasma drawn out from the plasma gun 10 into the film forming chamber 11 are concentrated on the protruding portion of the electrode 6 and flow into the electrode 6. Due to the inflow of electrons, a current flows through the electrode 6 and the electrode 6 is heated. At this time, since the contact area between the anode base 5 and the electrode 6 is adjusted, the amount of heat conduction from the electrode 6 to the anode base 5 can be adjusted, and the temperature of the electrode 6 can be made higher than that of the anode base 5. . Thereby, even if the film-forming particles reach the electrode 6, the electrode 6 is difficult to adhere because of the high temperature, and the electrode 6 is kept in a state where at least a part thereof is exposed, and discharge can be maintained. Further, as the temperature of the electrode 6 increases, the electrical resistance of the electrode 6 decreases, and more electrons easily flow into the electrode 6.

  The film forming apparatus of this embodiment will be specifically described.

  As shown in FIG. 1, a film formation chamber (chamber) 11 includes a substrate holder 13 that supports a substrate (film formation target) 14 to be formed, a material gas or reaction gas introduction pipe 17, and one or more ones. An evaporation source 12 and a heating device (not shown) for the evaporation source 12 are arranged. The substrate holder 13 incorporates a heater for heating the substrate 14. The evaporation source 12 is disposed on the bottom surface of the film forming chamber 11. The film forming chamber 11 is connected to an exhaust device (vacuum pump) for exhausting the inside.

  A plasma gun 10 is provided on a side surface of the film forming chamber 11. A plasma 105 is drawn from the plasma gun 10 into the film forming chamber 11 along the plasma axis 10. The plasma 105 activates the atmosphere in the film forming chamber 11. Thus, when the evaporation source 12 is heated by an electron beam, a film can be formed on the substrate 14 by ion plating. When the source gas is introduced into the film formation chamber 11 from the introduction tube 17, a film can be formed on the substrate 14 by plasma CVD.

  As shown in FIG. 2, the plasma gun 10 draws the cathode 1, the first intermediate electrode 2, the second intermediate electrode 3, the third intermediate electrode 4, the anode base 5, and the electrode 6 into a cylindrical plasma gun container 103. The structure is arranged in order along the axis 101. The anode base 5 and the electrode 6 constitute an anode. Here, the number of intermediate electrodes is three, but the number of intermediate electrodes can be selected so that the most stable discharge occurs depending on the type of discharge gas. The cathode 1, the first intermediate electrode 2, the second intermediate electrode 3, the third intermediate electrode 4, and the anode base 5 are insulated from each other by an insulator (not shown). An air-core coil 8 that generates a magnetic field for guiding the plasma 105 is disposed on the outer peripheral side of the anode base 5.

  The anode base 5 is provided with a cooling part 5a. For example, as the cooling unit 5 a, a water cooling structure (cavity) that allows cooling water to flow into the anode base 5 can be employed. The cathode 1, the first, second and third intermediate electrodes 2, 3 and 4 are also provided with cooling parts 1a, 2a, 3a and 4a such as water cooling, respectively.

  The cathode 1 has a known cathode structure suitable for arc discharge. The cathode 1 is provided with a discharge gas inlet 102.

  The first, second and third intermediate electrodes 2, 3, 4 and the anode base 5 are each cylindrical and have a through hole (orifice) having a predetermined diameter in the center. These through holes maintain the pressure of the plasma gun container 103 at a positive pressure rather than the film forming chamber 11 and form a pressure gradient. As a result, the plasma gun 10 constitutes a pressure gradient type plasma gun.

  The electrode 6 is connected to the anode base 5 as described above. As shown in FIG. 2, the electrode 6 has a structure in which a cylinder 6 a disposed so as to coincide with the plasma axis 101 in the axial direction and a disk 6 b having a through hole in the center are connected. The disc 6b is connected to the end of the cylinder 6a on the anode base 5 side. The surface of the disk 6b on the anode base 5 side is in contact with the anode base 5 with a predetermined area. Therefore, the electrode 6 is installed in a shape in which the end of the cylinder 6 a protrudes from the side surface of the anode base 5 on the film forming chamber 11 side toward the film forming chamber 11. The shape of the end of the electrode 6 may be any shape as long as it protrudes toward the film forming chamber 11, and the tip may be needle-shaped. Further, the contact portion of the electrode 6 with the anode base 5 may not be a disk having an opening, but may be any shape as long as electrical contact with the anode base 5 can be sufficiently obtained. For example, a rod-shaped electrode 6 may be inserted into the anode base 5. Alternatively, a cylinder having an outer diameter substantially equal to the inner diameter of the through hole of the anode base 5 may be used as the electrode 6 and may be inserted into the through hole of the anode base 5 and brought into contact therewith. In this case, the contact area between the electrode 6 and the anode base 5 can be adjusted by the depth at which the cylindrical electrode 6 is inserted into the anode base 5.

  Electrons intensively reach the electrode 6 from the plasma 105 at the tip (cylindrical end) on the film forming chamber 11 side, and electrons flow. Thereby, an electric current flows into the electrode 6, and the electrode 6 is heated by this electric current. Since the electrode 6 is in contact with the anode base 5 cooled by the cooling unit 5a, the heat of the electrode 6 is conducted to the anode base 5 and cooled. The contact area between the electrode 6 and the anode base 5 is set so that the electrode 6 has a higher temperature than the anode base 5 during plasma generation of the plasma gun 10. In particular, the contact area between the electrode 6 and the anode base 5 is such that the temperature of the electrode 6 during plasma generation of the plasma gun 10 is equal to or higher than the temperature at which the material deposited in the deposition chamber evaporates in the degree of vacuum in the plasma gun. It is preferable that it is designed to be. Thereby, since the film-forming particles that have reached the surface of the electrode 6 are re-evaporated by the heat of the electrode 6, it is possible to prevent the electrode 6 from increasing its resistance by being deposited during plasma generation. Specifically, for example, the temperature of the electrode 6 is preferably 1000 ° C. or higher, more preferably 2000 ° C. or higher, and particularly preferably 2500 ° C. or higher. In addition, the contact area between the electrode 6 and the anode base 5 is obtained and set in advance so as to be the above temperature by experiments and calculations.

  The electrode 6 has a high melting point (for example, 1000 ° C. or higher) and is made of a conductive material. In particular, a metal having a low electrical resistance is desirable. Specifically, for example, the electrode 6 can be formed of a material containing one or more of carbon, tungsten, and molybdenum. By forming the electrode 6 from a metal having a low electrical resistance, the electrode 6 has the same potential as the anode base 5, and electrically acts as the anode 50. In addition, since it is made of a high melting point metal, it does not melt or deform even at high temperatures.

  In the present embodiment, in order to prevent heat from being radiated (radiated) from the electrode 6 heated to a high temperature and heating the surrounding plasma gun container 103 and the film forming chamber (chamber) 11, as shown in FIG. As described above, the cooling unit 7 is disposed between the anode 50 and the film forming chamber 11. By cooling the cooling unit 7, it is possible to prevent the vacuum holding member (O-ring or the like) of the connection unit 12 between the plasma container 103 and the film formation chamber (chamber) 11 from being deteriorated by heating. For example, as the cooling unit 7, a water cooling flange can be used as shown in FIG. In particular, the cooling part 7 (water cooling flange) is shaped so as to protrude into the film forming chamber 11 as shown in FIG. 2, so that the radiant heat from the electrode 6 reaches the wall surface of the film forming chamber 11. Can be blocked. Therefore, the radiant heat can reach only the axial direction of the plasma 105 in the vacuum chamber 11. Since the axial direction of the plasma 105 is in a high temperature state by the plasma 105, no problem occurs even if heat from the electrode 6 is radiated.

  A DC power supply 16 is connected to the cathode 1 and the anode base 5 as shown in FIG. The first, second, and third intermediate electrodes 2, 3, 4 are connected to the positive electrode of the DC power supply 16 through the hollow resistors 21, 22, 23 having appropriate resistance values. The values of the enamel resistors 21, 22, and 23 are set so that the first, second, and third intermediate electrodes 2, 3, and 4 become higher potentials as they approach the anode 50 side from the cathode 1 side. Thereby, plasma can be extracted into the film forming chamber 11.

  The second intermediate electrode 3 includes a magnet 3b. The magnet generates a magnetic field and focuses the plasma. Thereby, the plasma passes through the first to third intermediate electrodes 2 to 4 and the through hole (orifice) of the anode 50.

  Hereinafter, the operation of each unit when plasma is generated to form a film on a substrate will be described using the apparatus of FIG.

  A substrate 14 is attached to the substrate holder 13, and a predetermined solid material is disposed in the evaporation source 12. A supply source of a predetermined material gas or reaction gas is connected to the introduction pipe 17. The inside of the plasma gun 10 and the film formation chamber 11 are evacuated to a predetermined pressure. A discharge gas such as Ar gas or He gas is supplied to the plasma gun 10, and a voltage is applied from the DC power supply 16 to the cathode 1, the first, second and third intermediate electrodes 2, 3, 4 and the anode 50. By applying this voltage, the discharge gas in the plasma gun 10 is ionized, and glow discharge plasma is generated. When the discharge current is gradually increased, the cathode in the cathode 1 is heated by the discharge current to become a hot cathode and generate a large current, and the inside of the plasma gun 10 shifts to arc discharge plasma.

  The electrons of the arc discharge plasma 105 of the plasma gun 10 pass through the through holes of the intermediate electrodes 2 to 4 while being accelerated by the potential difference between the first, second and third intermediate electrodes 2, 3 and 4 and the anode 50. Then, it further passes through the anode 50 and reaches the film forming chamber 11. The electrons that have reached the film forming chamber 11 give energy to the reaction gas, the material gas, and the material vapor from the evaporation source 12 and are activated. When the activated material vapor, material gas, or reactive gas (film formation particles) reaches the substrate 14, a high-quality film can be formed by ion plating or plasma CVD.

  Electrons in the plasma 105 are reflected by the space charge in the film forming chamber 11 and reach the tip of the electrode 6 in a concentrated manner. Thereby, discharge is maintained. Concentrating and reaching the tip of the electrode 6 makes it easier for a current to flow stably through the electrode 6, and discharge can be stably maintained. Further, the electrode 6 is heated by the flowing current, and is maintained at a high temperature of, for example, 1000 ° C. or higher. Therefore, since the material vapor that has reached the electrode 6 is re-evaporated on the surface of the electrode 6, the material vapor is not deposited on the electrode 6 and the electrode 6 is not covered with the film-forming particles. Therefore, it is possible to prevent the electrode 6 from increasing in resistance. In addition, since the electrode 6 is heated to have a low electric resistance, electrons are more concentrated and reach the electrode 6. Therefore, a more stable current flows through the electrode 6 and the discharge is stably maintained.

  The through holes (orifices) of the first to third intermediate electrodes 2, 3, 4 reduce the conductance of the gas passing therethrough, and the pressure difference (pressure gradient) between the cathode 1 region and the anode 50 region. Form. Thereby, the pressure in the cathode 1 region can be kept high and the anode 50 region can be kept at a low pressure, and the mean free path of ions in the cathode 1 region can be shortened. Therefore, damage to the cathode 1 due to ion backflow collision from the anode region can be avoided. Further, it is possible to prevent the chemically active gas from flowing into the region of the cathode 1 from the film formation chamber 11 side, and chemical damage to the cathode can be avoided.

  The air-core coil 8 generates a magnetic field that guides plasma. Uniform plasma without bias can be drawn straight into the vacuum vessel 11.

  Further, the water cooling part (water cooling flange) 7 blocks radiation heat from the electrode 6 and prevents damage to the vacuum holding member of the connection part 12 between the plasma gun and the film forming chamber 11 and the film forming chamber 11 itself due to heat. can do. As a result, it contributes to the stable maintenance of the plasma.

  As described above, in this embodiment, even when the insulating film is continuously formed by providing the electrode 6 that is electrically connected to the anode base 5 and heated to a high temperature by the discharge current, The vapor coming from the raw material evaporation source can prevent the electrode 6 from being deposited. Further, by providing the cooling unit (water cooling flange) 7, it is possible to block the radiant heat from the electrode 6 and prevent the film formation chamber from being damaged by the heat. Therefore, plasma can be stably maintained during film formation, and a high-quality thin film can be manufactured with good reproducibility. In addition, since the plasma at the initial stage of discharge can be stabilized, the time from when the plasma is generated until it reaches a desired discharge current can be shortened.

  Here, a method of manufacturing a perovskite oxide ferroelectric (PZT) film using the apparatus of FIG. 1 will be described. Pb, Zr, and Ti metals are prepared as materials for the evaporation source 12. These are structured to be heated independently by separate electron beams.

First, He gas is introduced into the plasma gun 10 as a carrier gas, and an arc discharge is generated by applying a DC bias voltage. High density plasma generated by arc discharge is guided into the film forming chamber 11. In this state, high-density oxygen plasma and oxygen radicals are generated in the film forming chamber 11 by introducing O ₂ gas as a reaction gas from the introduction pipe 17.

In the presence of a mixed plasma of He and O ₂ , deposition of PZT thin film can be performed by depositing on the substrate 14 while reacting the vapor of the source metal of the evaporation source 12 and the oxygen radical in the mixed plasma. . The substrate 14 is heated to a predetermined temperature by a heater in the substrate holder 13. By controlling the outputs of the three evaporation sources 12, an article having a PZT film of a perovskite oxide ferroelectric (crystal structure single phase) can be manufactured. In this thin film forming method, since the amount of oxygen radicals effective for film growth can be increased, it is possible to grow a PZT film at a high film formation rate.

The film that can be formed by the film forming apparatus of the present embodiment is not limited to the PZT film, and a desired film such as an oxide such as a SiO ₂ film or a TiO ₂ film, Si, or a transparent conductive film may be used. A film can be formed. The film forming method using the plasma gun of the present invention is capable of stably maintaining a discharge even if the film to be formed is an insulating film, so that an insulating thin film is formed and a particularly high film forming rate is required. It is suitable for the production of a product. For example, it is suitable for manufacturing articles having a hard coat for polycarbonate (PC) lenses for headlamps, a hard coat for PC transparent building materials such as windows, and a hard coat for PC use windows for automobiles.

  In the present embodiment, the reflective film forming apparatus in which the plasma drawn from the plasma gun 10 to the film forming chamber 11 returns to the anode 50 of the plasma gun 10 has been described. However, the anode 50 is placed in the film forming chamber 11. The present invention can be applied to a rectilinear film forming apparatus. In the case of the straight-ahead type, the anode 50 is disposed at a position where the plasma gun 10 is connected to the film formation chamber 11 and at a position in the film formation chamber 11 facing each other. The protruding portion (electrode 6) of the anode 50 is disposed so as to protrude toward the plasma gun 10. As a result, the plasma drawn out from the plasma gun 10 reaches the protruding portion (electrode 6) of the anode 50 arranged at the opposite position in the film forming chamber 11, and the protruding portion (electrode 6) is heated. The Therefore, film-forming particles are unlikely to adhere to the protruding portion (electrode 6), and discharge can be maintained.

DESCRIPTION OF SYMBOLS 1 ... Cathode, 2 ... 1st intermediate electrode, 3 ... 2nd intermediate electrode, 4 ... 3rd intermediate electrode, 5 ... Anode, 6 ... Electrode, 7 ... Cooling part (water cooling flange), 8 ... Air-core coil, 11 ... Deposition chamber, 12 ... evaporation source, 13 ... substrate holder, 14 ... substrate, 17 ... introduction tube, 16 ... DC power supply, 21, 22, 23 ... enamel resistance, 101 ... plasma axis, 102 ... discharge gas introduction port, 103 ... Plasma gun container

Claims (12)

A film forming chamber; and a plasma gun connected to the film forming chamber;
The plasma gun includes a cathode, which is disposed along an axial direction, and an anode including a portion protruding toward the film formation chamber. The film forming apparatus according to claim 1, wherein the anode includes an electrode protruding toward the film forming chamber, and an anode base disposed on the cathode side of the protruding electrode and in contact with the electrode.
The contact area between the electrode and the anode base is set such that the temperature of the electrode is higher than that of the anode base during plasma generation of the plasma gun.   The film forming apparatus according to claim 2, wherein the anode base is provided with a cooling unit.   The film forming apparatus according to claim 1, wherein a cooling unit is disposed between the anode and the film forming chamber.   5. The film forming apparatus according to claim 1, wherein a contact area between the electrode and the anode base is determined so that a temperature of the electrode during plasma generation of the plasma gun is set in the film forming chamber. A film forming apparatus, wherein the material to be formed is designed to have a temperature equal to or higher than a temperature at which the material is evaporated in a vacuum degree in the plasma gun.   6. The film forming apparatus according to claim 1, wherein the anode base is cylindrical, and a portion of the electrode protruding toward the film forming chamber is cylindrical. A film forming apparatus. A cathode, one or more intermediate electrodes, and an anode, disposed in order along the axial direction;
The plasma gun according to claim 1, wherein the anode has a shape protruding toward a side opposite to the intermediate electrode. 8. The plasma gun according to claim 7, wherein the anode protrudes toward the opposite side of the intermediate electrode, and an anode base disposed on the intermediate electrode side of the protruding electrode and in contact with the electrode; Including
The contact area between the electrode and the anode base is set so that the temperature of the electrode is higher than that of the anode base during plasma generation of the plasma gun. A method of manufacturing an article provided with a thin film by forming a thin film on a film formation target using plasma drawn from a plasma gun to a film forming chamber,
The plasma gun includes a cathode, one or more intermediate electrodes, and an anode including a portion protruding toward the film forming chamber, which are sequentially arranged along the axial direction. The plasma is drawn out from the film formation chamber to
During the generation of the plasma, at least a part of electrons contained in the plasma in the film forming chamber is caused to flow into the protruding portion of the anode, and the temperature of the protruding portion is set by the current generated in the protruding portion of the anode. A method for producing an article provided with a thin film, characterized in that film formation is carried out while maintaining a temperature higher than the anode base located on the intermediate electrode side with respect to the protruding portion.   10. The method for manufacturing an article having a thin film according to claim 9, wherein the protruding portion of the anode is heated by the electrons to a temperature at which the material of the thin film does not adhere to at least a part of the protruding portion. The manufacturing method of the articles | goods provided with the thin film characterized by the above-mentioned.   11. The method of manufacturing an article having a thin film according to claim 9 or 10, wherein the projecting portion is heated by the electrons to a temperature equal to or higher than a temperature at which the material of the thin film evaporates in a vacuum degree in the plasma gun. A method for producing an article comprising a thin film as a feature. 12. A method of manufacturing an article comprising a thin film according to claim 9, wherein the thin film is an oxide thin film or a perovskite oxide ferroelectric. A method for manufacturing an article.

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