JP5032198B2 - Method for forming metal oxide film - Google Patents

Description

  The present invention relates to a method for forming a metal oxide film, and more particularly to a film forming method for forming a metal oxide film using a coaxial vacuum arc evaporation source and an evaporation source including a sputtering target.

  Conventionally, an aluminum oxide (alumina) film is formed by various methods. For example, an alumina film formed in an oxygen atmosphere by sputtering, for example, has irregularities on the surface before and after firing. Even if the cross section of the alumina film after firing is observed with an SEM photograph, there is a problem that crystallization is not observed so much that a dense film is not obtained.

  The inventors formed an alumina film on the sapphire substrate by a sputtering method, but as is apparent from the comparative example described later, after firing this alumina film, the film surface has irregularities, It was confirmed that the film was not dense. Therefore, such an alumina film is not useful as an insulating film for a gas sensor or a film for supporting an exhaust gas catalyst.

Also, using a thin film forming apparatus equipped with a cathodic arc evaporation source and a sputtering evaporation source, first, a substrate pretreatment is performed using a cathodic arc evaporation source, and then a ceramic film or It is known to form a thin film such as an amorphous carbon film (see, for example, Patent Document 1). However, there is a problem that even if such an apparatus is used, there is no unevenness on the surface and it is difficult to form a dense alumina film.
JP 2002-30413 A (Claims etc.)

  An object of the present invention is to solve the above-mentioned problems of the prior art, and a film forming method for forming a dense metal oxide film (for example, an alumina film) having a flat surface and high crystallization. Is to provide.

The method for forming a metal oxide film according to the present invention includes a cylindrical trigger electrode and a cylindrical or cylindrical cathode electrode made of aluminum, titanium, or silicon having at least a tip formed of a metal material for vapor deposition. Using a coaxial vacuum arc deposition source in which a cylindrical anode electrode is coaxially arranged around the cathode electrode and spaced apart coaxially around the cathode electrode. sapphire placing the metal material constituting the cathode electrode in an oxidizing atmosphere in the film forming apparatus, silicon, and allowed deposited on a substrate made of SiC or stainless steel to form a metal oxide fine particles, and then the cathode electrode A metal oxide film was formed on the metal oxide fine particles using a vapor deposition source having a sputtering target composed of the same metal material or an oxide of the metal. Characterized by heating the substrate formed of the metal oxide film.

When forming the metal oxide film, an atmosphere for forming the film using a vapor deposition source including a sputtering target is an oxidizing atmosphere.

The metal oxide fine particles and the metal oxide film are formed using a film forming apparatus in which the coaxial vacuum arc evaporation source and the evaporation source including the sputtering target are provided in the same vacuum chamber, and then oxidized. Heating is performed in an atmosphere heating furnace.

  After forming aluminum oxide fine particles using an electrode composed of aluminum as the cathode electrode, aluminum oxide is oxidized using a target composed of aluminum oxide as a sputtering target while maintaining the atmosphere in the vacuum chamber. An aluminum oxide film is formed on the material fine particles.

  According to the present invention, metal oxide fine particles are formed on a substrate using a coaxial vacuum arc evaporation source, and then a metal oxide film formed thereon by sputtering is used to nucleate the fine particles during firing. By growing the crystal from the starting point of the growth, the crystal grows while being oriented to a predetermined crystal axis, and it is possible to form a flat and dense metal oxide film.

According to the embodiment of the film forming method of the present invention, the cylindrical trigger electrode and the columnar or cylindrical cathode electrode having at least a tip portion made of a metal material for vapor deposition are used to form a cylindrical insulator. A coaxial vacuum arc evaporation source that is fixed coaxially adjacent and sandwiched, and a cylindrical anode electrode is arranged coaxially around the cathode electrode, and the same metal material as the cathode electrode Alternatively, a deposition source provided with a sputtering target composed of an oxide material of the metal and a deposition apparatus provided in the same vacuum chamber is used to first drive the coaxial vacuum arc deposition source to oxidize. In a reactive atmosphere, a metal material constituting the cathode electrode is vapor-deposited on a substrate placed in a film forming apparatus to form metal oxide fine particles by reaction with oxygen atoms in the atmosphere. And driven to the evaporation source having a data ring target, while maintaining an oxidizing atmosphere in the vacuum chamber, after forming a metal oxide film on the metal oxide fine particles, formed in the metal oxide film By heating the substrate in a heating furnace in an oxidizing atmosphere, a flat and dense metal oxide film can be formed.

  According to the present invention, by forming metal oxide fine particles on a substrate with a coaxial vacuum arc evaporation source, the metal oxide film formed on the substrate by sputtering is then fired in a heating furnace. Inside, the above metal oxide fine particles are crystal-grown starting from the nucleus growth, and are oriented and grown on a predetermined crystal axis, thereby obtaining a flat and dense film.

  Hereinafter, as one embodiment of the present invention, after forming alumina fine particles using an electrode composed of aluminum as the cathode electrode, the sputtering target was composed of alumina while maintaining the atmosphere in the vacuum chamber. Description will be made mainly on the point of forming an alumina film on alumina fine particles using a target.

In view of the problems of the prior art described above, the present inventors have made extensive studies to efficiently produce a dense metal oxide film by a simple method, and have developed a coaxial vacuum arc deposition source, a sputtering deposition source, As a film forming apparatus preferably provided in the same vacuum chamber, for example, a device having the configuration shown in FIG. 1 was developed, and a useful metal oxide film was formed using this film forming apparatus 1.

  A substrate stage 12 on which the substrate S is placed is horizontally disposed below the vacuum chamber 11 of the film forming apparatus 1. The vacuum chamber 11 is provided with a rotation mechanism having a rotation driving means 13 such as a motor at the center of the back surface of the substrate stage so that the substrate stage 12 can be rotated in a horizontal plane.

  Further, it is preferable to provide a heating means 14 such as a heater on the surface opposite to the substrate mounting side of the substrate stage so that the substrate stage 12 can be heated so that the substrate S can be heated to a predetermined temperature if desired. .

  Above the vacuum chamber 11, a coaxial vacuum arc deposition source 15 and a sputtering deposition source 16, which will be described later, are respectively arranged obliquely with respect to the substrate stage 12 and at different positions.

  The coaxial vacuum arc vapor deposition source 15 is disposed at a predetermined angle with respect to the main surface of the substrate S placed on the substrate stage 12 with the tip of the cathode electrode 15a facing the substrate stage 12 side. . This angle can be changed so that the metal fine particles generated from the cathode electrode 15a can be incident on the main surface of the substrate S and obliquely incident uniformly. Thus, the metal fine particles can fly from the upper side to the lower side of the vacuum chamber 11 and can be deposited on the substrate S. The angle of the oblique incidence is not particularly limited as long as the metal fine particles can be uniformly irradiated onto the substrate.

An oxidizing gas introduction system 17, an inert gas introduction system 18 and a vacuum exhaust system 19 are connected to the wall surface of the vacuum chamber 11. The oxidizing gas introduction system 17 is an oxygen gas introduction system for making the inside of the vacuum chamber 11 an oxidizing atmosphere, and the inert gas introduction system 18 is an introduction system for an inert gas such as Ar. . In each gas introduction system, valves 17a and 18a, mass flow controllers 17b and 18b, valves 17c and 18c, and gas cylinders 17d and 18d are connected in this order by metal piping. The evacuation system 19 includes a conductance valve 19a, a turbo molecular pump 19b, a valve 19c, and a rotary pump 19d connected in this order by a metal vacuum pipe, and the inside of the vacuum chamber 11 is preferably 1.3 × 10 ^−4. It is configured so that it can be evacuated to Pa or less.

  As shown in FIG. 1, the coaxial vacuum arc vapor deposition source 15 provided in the film forming apparatus 1 has one end closed and the other end facing the substrate stage 12 opened, and is made of a metal material for producing metal fine particles. A cylindrical or cylindrical cathode electrode 15a, a cylindrical anode electrode 15b made of stainless steel, etc., and a cylindrical trigger electrode made of stainless steel or the like (for example, a ring-shaped trigger electrode) 15c and a disc-shaped or cylindrical insulator (hereinafter also referred to as a hat-type insulator) 15d provided to separate the cathode electrode 15a and the trigger electrode 15c from each other. It is attached coaxially. The cathode electrode 15 a is provided to face the substrate stage 12 in an oblique direction. Although not shown, the three components of the cathode electrode 15a, the insulator 15d, and the trigger electrode 15c are closely attached with screws or the like and attached coaxially. Further, although not shown, the anode electrode 15 b is attached to a vacuum flange by a support so that the angle with respect to the substrate stage 12 can be changed, and this vacuum flange is attached to the upper surface of the vacuum chamber 11. The cathode electrode 15a is coaxially provided inside the anode electrode 15b and separated from the wall surface of the anode electrode 15b by a certain distance. The cathode electrode 15a only needs to be made of a metal material at least at the tip (corresponding to the end of the anode 15b on the opening side).

  The trigger electrode 15c is attached with an insulator 15d made of alumina or the like sandwiched between the target material or the cathode electrode 15a. The insulator 15d may be attached to insulate the cathode electrode 15a from the trigger electrode 15c, and the trigger electrode 15c may be attached to the cathode electrode 15a via an insulator. It is preferable that the anode electrode 15b, the cathode electrode 15a, and the trigger electrode 15c are electrically insulated by an insulator 15d and an insulator. The insulator 15d and the insulator may be configured integrally or separately.

  A trigger power source 15e composed of a pulse transformer is connected between the cathode electrode 15a and the trigger electrode 15c, and an arc power source 15f is connected between the cathode electrode 15a and the anode electrode 15b. The arc power source 15f includes a DC voltage source 15g and a capacitor unit 15h. Both ends of the capacitor unit 15h are connected to the cathode electrode 15a and the anode electrode 15b, respectively. The capacitor unit 15h and the DC voltage source 15g are connected in parallel. Has been.

  The capacitor unit 15h is connected to one or a plurality of capacitors (one capacitor is illustrated in FIG. 1), and one capacitor thereof is, for example, 2200 μF (withstand voltage 160V), The DC voltage source 15g can be charged at any time. The trigger power supply 15c transforms the pulse voltage of μs of input 200V by about 17 times, and outputs 3.4 kV (several μA) and polarity: plus. The arc power supply 15f has a DC voltage source 15g having a capacity of 100V and several A, and the capacitor unit 15h (for example, 8800 μF in the case of four capacitor units) is charged from this DC voltage source. Since this charging time takes about 1 second, the period when discharging is repeated at 8800 μF in this system is 1 Hz. The positive output terminal of the trigger power supply 15e is connected to the trigger electrode 15c, and the negative terminal is connected to the same potential as the negative output terminal of the DC voltage source 15g of the arc power supply 15f, and is connected to the cathode electrode 15a. The plus terminal of the DC voltage source 15g of the arc power supply 15f is grounded to the ground potential and connected to the anode electrode 15b. Both terminals of the capacitor unit 15h are connected between a plus terminal and a minus terminal of the DC voltage source 15g.

  Reference numeral 20 in FIG. 1 denotes a controller, which is connected to the trigger power supply 15e. When a signal is input to the trigger power supply 15e connected to the controller by turning on the switch of the controller, the controller supplies a high voltage. Is output. The controller 20 is preferably connected to a CPU (not shown) and configured to operate the controller by a signal (external signal) from the CPU.

  Next, the vapor deposition source 16 provided with the sputtering target provided in the film forming apparatus 1 shown in FIG. 1 will be described.

  In the vapor deposition source 16 shown in FIG. 1, a sputtering power supply 16b is connected to a sputtering cathode electrode 16a via a cable 16c. The cathode electrode 16a is made of the same metal material as the cathode electrode 15a of the coaxial vacuum arc deposition source 15 or an oxide material of the metal, and functions as a sputtering target. The power source 16b is a high frequency power source. When the output of the power source 16b is applied to the cathode electrode, plasma is generated in the vicinity of the surface of the cathode electrode 16a in the vacuum chamber 11 so that normal sputtering can be performed. It is configured.

  Next, on the main surface of the substrate S placed on the substrate stage 12 in the vacuum chamber 11 using the film forming apparatus 1 provided with the coaxial vacuum arc deposition source 15 and the sputtering deposition source 16 shown in FIG. Next, a method for forming a metal oxide film on the fine particle after producing the metal oxide fine particle will be described. In this case, for convenience of explanation, a film forming method is performed using a cathode electrode made of aluminum as the cathode electrode 15a, a cathode electrode made of alumina as the cathode electrode 16a, and a sapphire substrate as the substrate.

First, the substrate is heated to a predetermined temperature (for example, 300 to 400 ° C.) by a heating means such as a heater, then valves 17a and 17c are opened, and a predetermined flow rate of oxidizing gas is supplied to the vacuum chamber via the mass flow controller 17b. 11 and the conductance valve 19a is adjusted to adjust the pressure in the vacuum chamber to 5 × 10 ⁻² Pa.

  The DC voltage source 15g charges the capacitor unit 15h with 100V, sets the capacitance of the capacitor unit 15h to 8800 μF, and then outputs a pulse voltage from the trigger power supply 15e to the trigger electrode 15c (output: 3.4 kV), By applying a hat-type insulator 15d between the cathode electrode 15a and the trigger electrode 15c, a trigger discharge (a creeping discharge on the surface of the hat-type insulator) is generated between the cathode electrode 15a and the trigger electrode 15c. Due to this trigger discharge, the electric charge stored in the capacitor unit 15h is vacuum arc discharged between the side surface of the cathode electrode 15a and the inner surface of the anode electrode 15b, and a large amount of arc current flows into the cathode electrode 15a. As a result, aluminum, which is a constituent metal material of the cathode electrode 15a, is evaporated, a plasma containing this constituent metal material is formed, and the discharge is stopped by the discharge of the electric charge stored in the capacitor unit 15h. This trigger discharge is repeated a predetermined number of times, and an arc discharge is induced for each trigger discharge. The number of trigger discharges and hence the number of arc discharges can be performed by inputting a desired number of discharges to the controller 20.

  During the arc discharge described above, fine particles (atomic ions, clusters, electrons, etc. that are turned into plasma) generated by melting of the constituent metal material are formed. The fine particles are discharged into the vacuum chamber 11 from the opening (discharge port) of the anode electrode 15b, and the fine particles formed as described above are supplied to the substrate S installed obliquely below the opening. Then, alumina fine particles, which are metal oxide fine particles, are deposited on the surface of the substrate S by reaction with an oxidizing gas such as oxygen gas.

  The metal fine particles are released as follows. Since a large amount of current flows through the cathode electrode 15a, a magnetic field is formed in the cathode electrode 15a, and electrons in the plasma generated at this time (the electrons fly from the cathode electrode 15a to the inner surface of the anode electrode 15b) are self-formed. It receives Lorentz force by the magnetic field and flies forward. On the other hand, the metal ions of the cathode electrode material in the plasma fly forward so that the electrons fly and polarize as described above and are attracted to the forward electrons by Coulomb force, and fine particles are supplied onto the substrate S. Will be.

  In the present embodiment, the length of the cable that is the wiring from the arc power source 15f to the coaxial vacuum arc deposition source 15 is set to about 1 m. Further, the cathode electrode 15a may be entirely made of a metal material, or the end of the anode electrode, which is the tip of the cathode electrode 15a, may be made of the metal material.

  Next, a metal oxide film is formed by sputtering on the metal oxide fine particles formed as described above. As the sputtering target for the cathode electrode, one made of alumina is used.

  The substrate stage 12 is kept at room temperature, the valves 17a and 17c of the oxidizing gas introduction system 17 are opened, the oxygen gas supplied via the mass flow controller 17b, and the valves 18a and 18c of the inert gas introduction system are opened, A mixed gas with an inert gas such as Ar supplied via the mass flow controller 18b is introduced into the vacuum chamber 11, the conductance valve 19a is adjusted, and the pressure in the vacuum chamber 11 is set to a predetermined pressure (for example, 0. 1 to 0.5 Pa, preferably 0.1 Pa). A high frequency (13.56 MHz) is applied from the high frequency power supply 16b to the sputtering cathode electrode 16a. Thereby, plasma is generated in the vicinity of the cathode electrode 16a to generate ions, and the ions sputter a target made of alumina, and alumina particles adhere to the substrate. When this sputtering process is continued for a predetermined time, an alumina film having a predetermined film thickness (for example, 300 nm) is formed on the substrate.

Next, the substrate having the metal oxide film formed on the metal oxide fine particles as described above is taken out from the vacuum chamber 11 and placed in a heating furnace, and in an atmosphere of an oxygen atom-containing gas such as air, Firing is performed at a predetermined pressure (for example, 1 atm) and a predetermined temperature (for example, 600 to 1000 ° C., preferably 900 ° C.) for a predetermined time (for example, 2 to 6 hours, preferably 5 hours). A desired metal oxide film is obtained.

  Examples of the substrate that can be used in the present invention include a substrate made of sapphire, silicon, SiC, stainless steel, or the like.

  Examples of the metal material for forming metal oxide fine particles include aluminum, titanium, and silicon. Examples of the sputtering target material include oxides of these metal materials.

  There is no restriction | limiting in particular as sputtering method in this invention, For example, long throw sputtering method may be sufficient. The long throw sputtering method is a method in which the distance between the target and the substrate is increased and sputtering is performed in a low pressure atmosphere, and film formation with high directivity is possible. In the case of forming an aluminum oxide film on a substrate by this method, an alumina target is installed in a film forming apparatus, and Ar gas and oxygen gas and the like are applied under a pressure of 0.05 to 0.1 Pa, for example. A film is formed on the substrate using a predetermined flow rate and flow rate ratio.

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

  Alumina fine particles are formed on the main surface of the substrate S placed on the substrate stage 12 in the vacuum chamber 11 using the film forming apparatus 1 having the coaxial vacuum arc deposition source 15 and the sputtering deposition source 16 shown in FIG. After that, an alumina film was formed on the fine particles. In this case, a cathode electrode made of aluminum was used as the cathode electrode 15a, a target made of alumina was used as the cathode electrode 16a, and a sapphire substrate was used as the substrate.

First, the sapphire substrate whose surface has been cleaned by washing and heat treatment is heated to 350 ° C. by the heater 14, then the valves 17a and 17c are opened, and a predetermined flow rate of oxygen gas is introduced into the vacuum chamber 11 via the mass flow controller 17b. Then, the conductance valve 18a was adjusted to adjust the pressure in the vacuum chamber to 5 × 10 ⁻² Pa.

  The DC voltage source 15g charges the capacitor unit 15h with 100V, sets the capacitance of the capacitor unit 15h to 8800 μF, and then outputs a pulse voltage from the trigger power supply 15e to the trigger electrode 15c (output: 3.4 kV), By applying a hat-type insulator 15d between the cathode electrode 15a and the trigger electrode 15c, a trigger discharge (a creeping discharge on the surface of the hat-type insulator) was generated between the cathode electrode 15a and the trigger electrode 15c. . Due to this trigger discharge, the electric charge stored in the capacitor unit 15h is vacuum arc discharged between the side surface of the cathode electrode 15a and the inner surface of the anode electrode 15b, and a large amount of arc current flows into the cathode electrode 15a. As a result, aluminum which is a constituent metal material of the cathode electrode 15a evaporates, a plasma containing the aluminum is formed, and the discharge is stopped by the discharge of the electric charge stored in the capacitor unit 15h. This trigger discharge was repeated 0 times, 10 times, 100 times, 1000 times. The number of trigger discharges, and hence the number of arc discharges, was performed by inputting a predetermined number of discharges to the controller 20.

  During the arc discharge described above, fine particles (atomic ions, clusters, electrons, etc. that are turned into plasma) generated by evaporation of aluminum are discharged into the vacuum chamber 11 from the opening (discharge port) of the anode electrode 15b, and the opening The fine particles formed as described above were made incident on the substrate S placed obliquely below, and alumina fine particles were produced by reaction with oxygen gas on the surface of the substrate S. The length of the cable which is the wiring from the arc power source 15f to the coaxial vacuum arc deposition source 15 was set to about 1 m.

  Next, as a sputtering target for the cathode electrode, an alumina film was formed by sputtering on the alumina fine particles formed as described above.

  The substrate stage 14 is kept at room temperature, the oxidizing gas introduction system valves 17a and 17c are opened, the oxygen gas supplied via the mass flow controller 17b, and the inert gas introduction system valves 18a and 18c are opened, A mixed gas with argon gas supplied via the mass flow controller 18b was introduced into the vacuum chamber 11, the conductance valve 19a was adjusted, and the pressure in the vacuum chamber 11 was adjusted to 0.1 Pa. By applying a high frequency (13.56 MHz) from the high frequency power supply 16b to the sputtering cathode electrode 16a, plasma is generated in the vicinity of the cathode electrode 16a to generate ions, and an alumina target is sputtered with the ions, and the alumina is sputtered. Particles were deposited on the substrate. This sputtering process was performed at a deposition rate of 1 nm / min for 5 hours to form an alumina film having a thickness of 300 nm on the substrate.

  Next, the substrate having the alumina film obtained as described above is taken out from the vacuum chamber 11 and placed in a heating furnace, and baked in an air atmosphere at 1 atm and 900 ° C. for 5 hours. An alumina film was obtained. By firing in a heating furnace, an alumina film was crystal-grown using alumina fine particles as a starting point for nucleus growth, and a flat and dense film was obtained. In addition, when the said sputtering process was performed without introduce | transducing oxygen gas, it also discovered that a crack generate | occur | produces in the alumina film | membrane in this baking process.

  In order to investigate the influence of the number of trigger discharges on the alumina film thus obtained, SEM photographs of the film surface before firing and the cross-section of the substrate at each of the above numbers are shown in FIGS. 2 (a) and 2 (b), respectively. Moreover, the SEM photograph of the film | membrane surface and board | substrate cross section after baking is shown to Fig.3 (a) and (b). Moreover, the XRD analysis was performed about the film | membrane obtained by each number of shots, and the result is shown in FIG.

As apparent from FIGS. 2 (a) and 2 (b), before firing, 0 shots (when the coaxial vacuum arc deposition source is not driven), that is, alumina fine particles are not formed on the substrate, and the coaxial vacuum There is almost no difference from the one in which the alumina fine particles are formed by driving the arc evaporation source, but when they are baked, as shown in FIGS. The growth method is different, and it can be seen that even 10 shots are flat and dense. Further, as is clear from FIG. 4, a strong spectrum can be observed in the vicinity of 57.5 ° in the X-ray diffraction (XRD) spectrum. This suggests that a thin film with high orientation was formed by epitaxial growth. That is, when the alumina fine particles are formed on the substrate, it means that a film having a flat and dense film quality and a highly oriented film is obtained crystallographically.
(Comparative Example 1)

  An alumina film was formed on the main surface of the sapphire substrate placed on the substrate stage in the vacuum chamber using the sputtering deposition apparatus shown in FIG.

  A substrate stage 62 on which the substrate S is placed is disposed horizontally below the vacuum chamber 61 of the vapor deposition apparatus shown in FIG. The vacuum chamber 61 is provided with a rotation mechanism having a rotation driving means 63 such as a motor at the center of the back surface of the substrate stage so that the substrate stage 62 can be rotated in a horizontal plane.

  Further, a heating means 64 such as a heater may be provided on the surface of the substrate stage opposite to the substrate mounting side so that the substrate stage 62 can be heated, so that the substrate S can be heated to a predetermined temperature if desired.

  A sputtering power source 66 is connected to the sputtering cathode electrode 65 via a cable 66a. The cathode electrode 65 is made of alumina and functions as a sputtering target. The power source 66 is a high frequency power source. When the output of this power source is applied to the cathode electrode 65, plasma is generated near the surface of the cathode electrode 65 in the vacuum chamber 61 so that normal sputtering can be performed. It is configured.

An oxygen gas introduction system 67, an argon gas introduction system 68, and a vacuum exhaust system 69 are connected to the wall surface of the vacuum chamber 61. In each gas introduction system, valves 67a and 68a, mass flow controllers 67b and 68b, valves 67c and 68c, and gas cylinders 67d and 68d are connected in this order by metal piping. These gas introduction systems 67 and 68 introduce gas into the vacuum chamber 61 to generate plasma. The vacuum exhaust system 69 includes a conductance valve 69a, a turbo molecular pump 69b, a valve 69c, and a rotary pump 69d connected in this order by a metal vacuum pipe. The conductance valve 69a is adjusted to adjust the pressure in the vacuum chamber 61. Can be adjusted to 5 × 10 ⁻² Pa.

  An alumina film was formed on the sapphire substrate according to the following process using the sputtering deposition apparatus of FIG.

  First, the sapphire substrate S whose surface was cleaned by washing and heat treatment was placed on the substrate stage. The substrate stage 62 is kept at room temperature, the valves 67a and 67c of the oxygen gas introduction system 67 are opened, the oxygen gas supplied via the mass flow controller 67b, and the valves 68a and 68c of the argon gas introduction system 68 are opened, and the mass flow is performed. A mixed gas with argon gas supplied via the controller 68b was introduced into the vacuum chamber 61, the conductance valve 69a was adjusted, and the pressure in the vacuum chamber 61 was adjusted to 0.1 Pa. By applying a high frequency (13.56 MHz) to the sputtering cathode electrode 65 from the high frequency power supply 66, plasma is generated in the vicinity of the cathode electrode 65 to generate ions, and the alumina target is sputtered with the ions, Alumina particles were deposited on the substrate S. This sputtering process was continued for 5 hours to form an alumina film having a thickness of 300 nm on the substrate.

  Next, the substrate having the alumina film obtained as described above is taken out from the vacuum chamber 61 and placed in a heating furnace, and fired at 1 atm and 900 ° C. for 5 hours in an air atmosphere to obtain an alumina film. It was.

  According to the SEM photograph observation of the film surface before firing and the cross section of the substrate with respect to the alumina film thus obtained, the results similar to the 0 shots in FIGS. 2 (a) and (b) are shown, respectively. According to the SEM photograph observation of the film surface and the substrate cross section, the same results as the zero shot in FIGS. 3A and 3B were shown, respectively. That is, the obtained alumina film had irregularities on the surface before and after firing, and was not very crystallized even after firing, as seen from a cross-sectional photograph, and was not a dense film.

  According to the present invention, a fine metal oxide film having a flat surface can be formed, which is useful as an insulating film for a gas sensor and a film for supporting an exhaust gas catalyst, and is used in the sensor technical field and the catalytic technical field. Is possible.

The structural example which shows typically the structural example of the film-forming apparatus used with the film-forming method of this invention. About the alumina film | membrane before baking obtained in Example 1, (a) is a substrate cross-sectional SEM photograph, (b) is a film | membrane surface SEM photograph. About the alumina film | membrane after baking obtained in Example 1, (a) is a substrate cross-sectional SEM photograph, (b) is a film | membrane surface SEM photograph. The XRD spectrum of the alumina film | membrane after baking obtained in Example 1. FIG. The sputtering vapor deposition apparatus used in Comparative Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 11 Vacuum chamber 11 In a vacuum chamber 12 Substrate stage 13 Rotation drive means 14 Heating means 15 Coaxial vacuum arc evaporation source 15a Cathode electrode 15b Anode electrode 15c Trigger electrode 15d Insulator 15e Trigger power supply 15f Arc power supply 15g DC voltage source 15h Capacitor unit 16 Sputtering evaporation source 16a Sputtering cathode electrode 16b Sputtering power supply 16c Cable 17 Oxidizing gas introduction system 17a, 17c Valve 17b Mass flow controller 17d Gas cylinder 18 Inert gas introduction system 18a, 18c Valve 18b Mass flow controller
18d Gas cylinder 19 Vacuum exhaust system 19a Conductance valve 19b Turbo molecular pump 19c Valve 19d Rotary pump 20 Controller 61 Vacuum chamber 62 Substrate stage 63 Rotation drive means 64 Heating means 65 Sputtering cathode electrode 66 Sputtering power supply 66a Cable 67 Oxygen gas introduction system 67a 67c Valve 67b Mass flow controller 67d Gas cylinder 68 Argon gas introduction system 68a, 68c Valve 68b Mass flow controller 68d Gas cylinder 69 Vacuum exhaust system 69a Conductance valve 69b Turbo molecular pump 69c Valve 69d Rotary pump S Substrate

Claims (4)

A cylindrical trigger electrode and a columnar or cylindrical cathode electrode made of aluminum, titanium, or silicon having at least a tip made of a metal material for vapor deposition are coaxially adjacent to each other with a cylindrical insulator interposed therebetween. A metallic material that constitutes the cathode electrode in an oxidizing atmosphere using a coaxial vacuum arc deposition source that is fixed and has a cylindrical anode electrode coaxially disposed around the cathode electrode. sapphire, which is placed in the film forming apparatus, silicon, and allowed deposited on a substrate made of SiC or stainless forming the metal oxide fine particles, and then configured with an oxide of the same metal material or metal and the cathode electrode after forming the metal oxide film on the metal oxide particles using a vapor deposition source with a sputtering target, a substrate formed of the metal oxide film Method of forming a metal oxide film, characterized by heat. 2. The method for forming a metal oxide film according to claim 1, wherein when forming the metal oxide film, an atmosphere for forming the film using an evaporation source provided with a sputtering target is an oxidizing atmosphere. The metal oxide fine particles and the metal oxide film are formed using a film forming apparatus in which the coaxial vacuum arc evaporation source and the evaporation source including the sputtering target are provided in the same vacuum chamber, and then oxidized. 3. The method for forming a metal oxide film according to claim 1, wherein heating is performed in a heating furnace in an atmosphere.   After forming aluminum oxide fine particles using an electrode composed of aluminum as the cathode electrode, aluminum oxide is oxidized using a target composed of aluminum oxide as a sputtering target while maintaining the atmosphere in the vacuum chamber. The method for forming a metal oxide film according to claim 1, wherein an aluminum oxide film is formed on the product fine particles.