JP2007119806A - Method of forming dielectric thin film and high-frequency magnetron sputtering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a dielectric thin film having the same characteristics and excellent thermal stability at a stable deposition rate by high-frequency magnetron sputtering. <P>SOLUTION: In the high-frequency magnetron sputtering, a DC voltage is induced in a target by the high-frequency electric power applied to the target. According to the method of formation, the deposition is performed by regulating the absolute value of a DC component of the voltage to be induced in the target to ≥50V and thereby the deposition of the dielectric thin film at the stable deposition rate is made possible and the film of a specified refractive index value is made obtainable. Further, the thermal stability of the obtained film is improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for forming a dielectric thin film.

  Magnetron sputtering, which is performed by applying high-frequency power to a target, is widely used as a method for forming a thin film on a substrate. However, when film formation is performed, there is a problem that the film formation speed changes with time (Non-Patent Document 1). When the film formation rate changes during film formation, in order to obtain a constant film thickness, it is necessary to monitor the film thickness during film formation or to provide a control means for stabilizing the film formation rate. As a technique for stabilizing such a film formation rate, a high-frequency current and a high-frequency voltage applied to a target are measured, and the output of a high-frequency power source, a reactive gas partial pressure, sputtering, and the like are calculated based on the calculated phase difference. Patent Document 1 describes a technique for controlling gas partial pressure and the like. Non-Patent Document 2 discloses a magnetic circuit that generates a strong magnetron magnetic field disposed on the back surface of a target when a magnetic film is formed using a target made of a magnetic material in accordance with the consumption of the target. Thus, a method is described in which the DC component of the cathode voltage induced in the cathode is made constant by retreating from the target and changing the magnetic field.

JP 2000-144417 A P. G. Quigley, R.A. A. Rao and C.M. B. Eom, J. et al. Vac. Sci. Technol. A, 15 (1997), p. 2854. Akinori Furuya and Shigeru Hirono, J. et al. Appl. Phys. 87 (2000), p. 939.

  In order to stabilize the film formation rate, the film thickness is monitored during film formation, or the high-frequency current and high-frequency voltage at the target are measured during film formation and applied based on the calculated phase difference, etc. In the conventional technology, which controls the high-frequency power, reactive gas partial pressure, sputtering gas partial pressure, etc., or adjusts the position of the magnetic circuit on the back of the target, a measurement means is provided or the measurement result is calculated. There is a problem that it is necessary to provide means for adjusting the film forming conditions, and the complexity of the apparatus and its control mechanism cannot be avoided.

  In order to solve the above-mentioned problems, the present invention applies high-frequency power between a target made of a dielectric material and an anode disposed in the vicinity of the target to increase the plasma density on the target surface. A method of forming a dielectric thin film by magnetron sputtering for forming a dielectric thin film on a substrate under a magnetron magnetic field of which the absolute value of the direct current component of the cathode voltage induced in the target is 50 V or more. A method for forming a dielectric thin film is provided.

  The magnetron magnetic field on the target surface has a magnetic flux density at one position where the direction of the magnetic flux line is horizontal with respect to the target surface, and a plurality of positions where the direction of the magnetic flux line is horizontal. It is preferable that the minimum value of the magnetic flux density at each position is 0.005 to 0.025T.

  Further, the magnetron magnetic field is generated by a set of magnets disposed on the back side of the target, and the set of magnets includes a first magnet disposed in the center of the target and a first magnet disposed on the outer edge. 2 and an auxiliary magnet arranged between the first magnet and the second magnet, and the magnetron magnetic field has an absolute value of a component perpendicular to the target surface of the magnetic flux density on the target surface. The ratio of the width in the range of 0.01 T or less to the target width is 10% or more, and the vertical component of the magnetic flux density on the target surface is a magnetic field having at least one maximum value and minimum value in the range. It is preferable.

Moreover, it is preferable that the said anode is arrange | positioned adjacently over the perimeter of the said target, and the space | interval of the nearest part of the said target and the said anode is 1-10 mm.
The present invention is also the target is a target made of glass whose main component is Bi ₂ O _3, to provide a method of forming a dielectric thin film made of a glass film composed mainly of Bi ₂ O _3.

  The present invention further includes a target made of a dielectric material, an anode disposed in proximity to the target, and a magnetron magnetic field that increases the plasma density of the target surface, and the target and the anode are placed in a reduced pressure atmosphere. A high-frequency magnetron sputtering apparatus for applying a high-frequency voltage between them to form a dielectric thin film on a substrate, wherein a magnetic circuit for generating a magnetron magnetic field on the target surface has a horizontal magnetic flux line direction on the target surface. If there is a single position, the magnetic flux density at that position, and if there are multiple positions where the direction of the magnetic flux lines is horizontal, the minimum value of the magnetic flux density at each position is 0.005 to 0.025 T. A magnetic circuit for generating a magnetic field, wherein a direct current component of a cathode voltage induced on the target at the time of film formation To provide a high frequency magnetron sputtering apparatus being controlled so as to pair value is equal to or greater than 50 V.

  When the dielectric thin film forming method and the high-frequency magnetron sputtering apparatus of the present invention are used, the substrate is formed by magnetron sputtering at a stable film forming speed without measuring and controlling the film forming conditions and adjusting the magnetic circuit position. A dielectric thin film can be formed thereon. In addition, a dielectric thin film having a certain film characteristic can be easily obtained.

The substrate for forming a thin film used in the present invention is preferably a flat substrate, particularly a glass substrate, but is not limited thereto, and various substrates can be used depending on the purpose.
Materials that can be used as a target in the method for forming a dielectric thin film of the present invention include SiO ₂ , Bi ₂ O ₃ , Al ₂ O ₃ , Ga ₂ O ₃ , La ₂ O ₃ , CeO ₂ , and Er ₂ O _3. , Oxides such as B ₂ O ₃ , GeO ₂ , Y ₂ O ₃ , YBa ₂ Cu ₃ O ₇ and mixtures thereof, nitrides such as Si ₃ N ₄ , fluorides such as MgF ₂ , or components thereof The dielectric material such as glass material is exemplified, but the material is not limited thereto, and is appropriately selected according to the thin film material to be formed. At the time of film formation, the substrate may be fixed, and may be transported or rotated or revolved by using a carousel type substrate holder.

Magnetron sputtering is preferably performed by applying high-frequency power between the target and the anode in a reduced pressure atmosphere of 0.01 to 100 Pa to generate plasma in the space in front of the target. By applying high frequency power, a negative high voltage is induced on the target, and the gas field in the plasma is accelerated by the electric field generated by this high voltage, collides with the target, and knocks out atoms or molecules on the target surface. A thin film is formed on the substrate by depositing the target atoms or molecules thus knocked out on the substrate. As an atmosphere for performing sputtering, an inert gas such as Ar, Ne, Kr, and Xe and a mixed gas thereof, or a reactive gas such as O ₂ , N ₂ , and CO _{2 is} added to the inert gas and the mixed gas thereof. A mixed gas atmosphere in which is mixed is preferably exemplified, but is not limited thereto.

A magnetic circuit for generating a magnetron magnetic field for increasing the plasma density is disposed on the rear surface of the target.
The anode is usually arranged adjacent to the entire circumference of the outer periphery of the target, and high frequency power is applied between the anode and the target. The frequency of the high frequency power is not limited, but 1 MHz to 40.68 MHz is preferable. The input power to the target is preferably 0.5 to ⁷ W / cm ^2, but is not limited thereto.
In magnetron sputtering, the cathode voltage induced on the target by the application of high frequency power is composed of a high frequency component and a direct current component. In the method for forming a dielectric thin film of the present invention, the absolute value of the DC component of the cathode voltage induced in the target (hereinafter referred to as “induced DC voltage”) is 50 V or more. By setting it to 50 V or more, it is possible to suppress a change in film formation rate when film formation is continuously performed. In order to suppress the change in the film forming rate to a smaller value, it is preferably set to 200 V or higher. The induced DC voltage is preferably 2000 V or less. If it exceeds 2000 V, the target may be cracked. The induced DC voltage can be measured by using, for example, a high-voltage passive probe and an oscilloscope for the voltage at the terminal portion on the back surface of the target for supplying high-frequency power.

  The magnetron magnetic field is preferably distributed such that the magnetic flux density (hereinafter simply referred to as “magnetic field strength”) at a position where the direction of the magnetic flux lines is horizontal on the target surface is 0.005 to 0.025 T. In addition, when there are a plurality of positions in the magnetron magnetic field where the direction of the magnetic flux lines is horizontal on the target surface, it is preferable that the distribution has a minimum magnetic flux density of 0.005 to 0.025 T at those positions. . By using a magnetron magnetic field having such a magnetic field strength, the DC voltage induced in the target can be set to the aforementioned value.

  Further, when the spatial region in the vicinity of the target is viewed in a cross section including the target center, the absolute value of the magnetic flux density in the range where the direction of the magnetic flux lines is substantially horizontal on the target surface, that is, the direction perpendicular to the target surface (hereinafter referred to as The range (hereinafter referred to as “vertical component of magnetic flux density”) is 0.01T or less, and the distribution of the vertical component of magnetic flux density within the above range has at least one maximum value and at least one minimum value (hereinafter, “ If the range of the horizontal magnetic field is increased by 10% or more with respect to the target width, a change in DC voltage induced in the target when sputtering is performed for a long time can be suppressed. In addition, changes in film formation speed and film characteristics can be suppressed to a small level. Furthermore, the film formation rate and the material utilization efficiency of the target are improved. When the target is circular, the target width is the target diameter.

  In the present invention, the distance between the anode disposed adjacent to the target and the target (hereinafter referred to as “the distance between the target and the anode”) is preferably 1 mm or more. In order to increase the direct current component induced in the target, it is more preferably set to 3 mm or more. If the thickness exceeds 10 mm, the target is held, and film adhesion to the backing plate bonded to the back surface of the target becomes conspicuous, which may cause a foreign matter defect. The anode is preferably arranged so that the inner edge of the anode does not fog the target surface when viewed from the direction perpendicular to the target surface.

  According to the method for forming a dielectric thin film of the present invention, a dielectric thin film having substantially the same composition as the target can be obtained. In the method for forming a dielectric thin film according to the present invention, a film can be formed at a stable film forming speed, and a thin film having a certain characteristic can be obtained. When performing, it can use preferably. The thickness of the thin film formed by the dielectric thin film forming method of the present invention is appropriately selected as necessary, but is preferably 0.001 to 20 μm, and more preferably 0.01 to 10 μm.

In addition, since a thin film with a certain characteristic can be obtained, it is necessary to form a dielectric thin film with a precise control of the refractive index value as in an optical waveguide formed using a dielectric thin film made of multicomponent glass. In such a case, it can be preferably used. Such an optical waveguide formed using a dielectric thin film made of a multi-component glass, or an optical waveguide having a core composed of Bi ₂ O ₃ based glass, Bi ₂ O ₃ in particular a rare earth element such as Er An optical waveguide having a core made of a system glass is exemplified.

FIG. 1 shows a conceptual diagram of a cross section of such an optical waveguide. The optical waveguide of FIG. 1 includes a clad made of a lower clad 12 and an upper clad 14 formed on a substrate 11, and a core 13. Optical waveguide of Figure 1, for example, on the substrate 11, are clad and core, on the other mainly composed of _Bi 2 _{O 3} and _Bi 2 _{O 3} based multi-component glass film containing SiO ₂ or the like several components sequentially In addition to stacking, a desired core pattern is formed by photolithography and dry etching. By forming a Bi ₂ O ₃ multicomponent glass thin film as a clad and a core by the dielectric thin film forming method of the present invention, it can be formed at a stable film formation rate, and the refractive index of the film and The film composition is precisely controlled to a desired value, and good reproducibility for each lot can be obtained.

  Examples of the present invention and comparative examples will be described below. Examples 1 and 2 are examples, and examples 3 and 4 are comparative examples.

[Example 1]
Bi ₂ O ₃ 76.99 wt%, Al ₂ O ₃ 2.81 wt%, Ga ₂ O ₃ 10.32 wt%, La ₂ O ₃ 1.80 wt%, CeO ₂ 0.14 wt%, SiO ₂ 7.94 wt% A disk-shaped target 23 having a diameter of 101.6 mm and a thickness of 3 mm made of a Bi-based multicomponent glass having a composition was produced, and this was bonded to a copper backing plate 24. The Bi-based multi-component glass target 23 bonded to the backing plate 24 was set on the magnetron cathode of a high-frequency magnetron sputtering apparatus (SPC-350 manufactured by Anelva). A schematic cross-sectional view around the target at this time is shown in FIG.

  In this example, the magnetron magnetic field is a magnetic circuit manufactured by designing the dimensions and magnetic force so that the magnetic flux density distribution on the target surface is the rotationally symmetric magnetic field distribution shown in FIG. Generated by 25A. FIG. 2 is a graph in which the horizontal component Bx and the vertical component Bz of the magnetic flux density on the target surface are plotted against the distance from the target center. In this example, the magnetic circuit 25A is composed of a set of magnets made of Nd—Fe—B permanent magnets and a yoke 25c made of SUS430, and generates a tunnel-like magnetron magnetic field. The set of magnets widens the range of the horizontal magnetic field of the tunnel-like magnetic field with the center magnet 25a as the first magnet having a circular cross section and the outer edge magnet 25b as the second magnet having a circular cross section. The auxiliary magnet 25d, which is provided in order to have an extreme value of the distribution of the vertical component of the magnetic flux density and in which two magnets having an annular cross section are arranged concentrically and combined, It is held at a predetermined position by the nonmagnetic auxiliary yoke 25e.

The magnetic circuit 25 </ b> A and the target 23 bonded to the backing plate 24 are assembled to the cathode body 26. As can be seen from FIG. 2, the magnetic field strength by this magnetic circuit is the magnetic flux density at the position where the direction of the magnetic flux is horizontal on the target surface (hereinafter referred to as “magnetic field strength of the magnetic circuit”), that is, the horizontal direction of the magnetic flux at that position. Component Bx is 0.01T. Further, the vertical component Bz of the magnetic flux on the target surface is 0.01 T or less, that is, the width of the horizontal magnetic field range is 20 mm in the graph of FIG. 2, and the vertical component Bz of the magnetic flux within this horizontal magnetic field range. Has one maximum and one minimum. The ratio of the width of the horizontal magnetic field range to the target width is 39%.
As the anode 27, an annular electrode having an inner diameter of 108 mm was used with the target surface and upper surface aligned and the center aligned. At this time, the distance between the target and the anode is 3.2 mm.

Prior to film formation, the inside of the chamber is evacuated to 5.4 × 10 ⁻⁵ Pa or less with a rotary pump and a turbo molecular pump in order to remove the influence of residual gas, and then the flow rate is controlled by a mass flow controller to control Ar gas at 30 sccm, A plasma 22 is generated by applying a high frequency of 13.56 MHz and a power of 120 W to the target from the high frequency power supply 28 in an atmosphere in which a mixed gas of 0.5 sccm of O ₂ gas is introduced and the pressure in the chamber is 0.3 Pa. Dielectric made of Bi-based multi-component glass on a disc-shaped soda-lime silica glass substrate 11 having a diameter of 76.2 mm and a thickness of 1 mm set in a carousel-type substrate holder (not shown) rotated at 6 rpm. The body thin film 21 was formed.

  The DC voltage induced in the target 23 is a high-voltage passive probe (Nippon Tektronix P6009) and an oscilloscope (Nippon Tektronix TDS-520) (both shown) with respect to the high frequency power terminal to the cathode body 26. ) Was used for measurement. The refractive index and film thickness of the formed film were measured at a wavelength of 1304 nm with a prism coupler (Model 2010 manufactured by Metricon). The changes in the deposition rate and refractive index at this time are summarized in the graphs of FIGS. The DC voltage induced on the target was 270 V at the start of film formation. Further, when the film formation was continued, the change in the DC voltage induced on the target was 0.6 V per 1 μm film thickness, that is, 0.6 V / μm.

The formation of the film and the measurement using the prism coupler were repeated, and the obtained Bi-based multicomponent glass film 21 was subjected to a heat treatment, and the film thickness and refractive index before and after the heat treatment were measured. The heat treatment is first evacuated to 1.33 Pa or less using a heat treatment apparatus that can be evacuated, and then heated to 350 ° C. at 5 ° C./min in an atmosphere in which 5 sccm of O ₂ gas is flowed to a pressure of 26.6 Pa. Then, after holding for 3 hours, the temperature was lowered to room temperature at 5 ° C./min.

[Example 2]
A dielectric thin film made of Bi-based multi-component glass was formed using the same Bi-based multi-component glass target 23 using the same high-frequency magnetron sputtering apparatus as in Example 1. However, the magnetic circuit disposed on the back surface of the target was changed to a magnetic circuit 25B that does not include the auxiliary magnet 25d and the nonmagnetic auxiliary yoke 25e. FIG. 5 shows a schematic sectional view around the target. The magnetic field intensity of this magnetic circuit 25B is 0.01T, and the magnetic flux density distribution on the target surface as seen in a cross section including the target center is as shown in FIG. 4, and the width of the horizontal magnetic field range is 19 mm. The ratio of the width of the horizontal magnetic field range to 1/2 of the target width is 37%, but the vertical component Bz of the magnetic flux has neither a maximum nor a minimum value within the range of the horizontal magnetic field.

  Sputtering was performed in the same manner as in Example 1 for the anode 27 and film formation conditions, and the Bi-based multicomponent glass film 21 of this example was obtained. The changes in the deposition rate and refractive index at this time are summarized in the graphs of FIGS. The DC voltage induced in the target was 572 V at the start of film formation, and the change in DC voltage induced in the target was 0.8 V / μm.

[Example 3]
In the same manner as in Example 1, a dielectric thin film made of Bi-based multicomponent glass was formed. However, the magnetic circuit disposed on the back surface of the target was a magnetic circuit 25B that does not include the same auxiliary magnet as in Example 2. The magnetic field intensity of the magnetic circuit 25B was 0.03T. The magnetic flux density distribution on the target surface when viewed in a cross section including the center of the target is as shown in FIG. 6, the width of the horizontal magnetic field range is 7 mm, and the ratio of the width of the horizontal magnetic field range to the target width is 14%. However, the vertical component Bz of the magnetic flux density does not have a maximum value or a minimum value within the range of the horizontal magnetic field. In addition, an annular electrode having an inner diameter of 92 mm was disposed on the anode 27 with its center aligned with a target having a diameter of 101.6 mm. At this time, since the diameter of the inner edge of the anode is smaller than the outer periphery of the target, the lower surface of the inner edge of the anode was placed 2 mm above the target surface. The distance between the target and the anode is 4.8 mm.

  Sputtering was performed under the same film forming conditions as in Example 1 to produce the Bi-based multi-component glass film 21 of this example, and the changes in film forming speed and refractive index at this time are summarized in the graphs of FIGS. . The DC voltage induced in the target was 20 V at the start of film formation, and the change in DC voltage induced in the target was 1.1 V / μm.

[Example 4]
In the same manner as in Example 1, a dielectric thin film made of Bi-based multicomponent glass was formed. However, the magnetic circuit disposed on the back surface of the target was a magnetic circuit 25B that does not include the same auxiliary magnet as in Example 2. The magnetic field intensity of the magnetic circuit 25B was set to 0.1T. The magnetic flux density distribution on the target surface as seen in the cross section including the target center is as shown in FIG. 7. The horizontal magnetic field range width is 2 mm, and the ratio of the horizontal magnetic field range width to the target width is 4%. However, the vertical component Bz of the magnetic flux density does not have a maximum value or a minimum value within the range of the horizontal magnetic field. The anode 27 was the same as in Example 3.

  Sputtering was performed under the same film forming conditions as in Example 1 to produce the Bi-based multi-component glass film 21 of this example, and the changes in film forming speed and refractive index at this time are summarized in the graphs of FIGS. . The DC voltage induced in the target was 4 V at the start of film formation, and the change in DC voltage induced in the target was 1.3 V / μm.

<Evaluation of change in film formation rate and thermal stability of films formed in Examples 1 to 4>
FIG. 8 is a graph in which the film formation rate obtained by dividing the film thickness immediately after film formation by the film formation time is plotted against the integrated film thickness formed from the same target. Here, the film formation rate on the vertical axis was normalized by the initial film formation rate obtained from the same target. FIG. 9 is a graph in which the refractive index immediately after film formation is plotted against the integrated film thickness formed from the same target. In addition, FIG. 10 shows the result of summarizing the change rate of the film thickness before and after the heat treatment for each sample with respect to the integrated film thickness. FIG. 11 is a graph in which the refractive index change after heat treatment is similarly plotted against the integrated film thickness.

  As can be seen from FIG. 8, in Examples 1 and 2, the film formation rate was not substantially decreased, and film formation with an integrated film thickness of 28 μm or more could be performed from the same target. Therefore, in Example 4, the film formation rate decreased from the beginning. As can be seen from FIG. 9, the refractive index of the formed film is constant within ± 0.002 even when film formation with an integrated film thickness of 28 μm or more is performed in Examples 1 and 2. Thus, the integrated film thickness with which the same refractive index variation width within ± 0.002 was obtained was 26 μm or less in Example 3, and 12 μm or less in Example 4.

Further, even when film formation with an integrated film thickness of 28 μm is performed from the same target, the rate of change of the film thickness before and after the heat treatment is as small as −1 to + 1% in Example 1 and −1 to + 3% in Example 2, and the heat treatment with a refractive index. The change before and after is as small as −0.001 to 0.000 in Example 1 and −0.002 to +0.003 in Example 2.
On the other hand, the change rate of the film thickness due to the heat treatment is large as −1 to + 4% in Example 3, and +3 to + 4% in Example 4, and the change in the refractive index due to the heat treatment is −0.016 to −0 in Example 3. .010, Example 4 has a large value of -0.034 to -0.024. That is, in Example 1 and Example 2, it turned out that the film | membrane excellent in thermal stability is obtained stably.

  According to the thin film manufacturing method of the present invention, when applied to the formation of a film whose film characteristics change due to a change in film forming speed, particularly a dielectric film, a thin film having stable characteristics can be easily reproduced with a stable film thickness. It is well obtained. In addition, a film having high thermal stability can be obtained.

The conceptual diagram of the cross section of an optical waveguide. The figure which shows magnetic flux density distribution (horizontal direction Bx, vertical direction Bz) on the target surface at the time of using the magnetic circuit of Example 1. FIG. The schematic sectional drawing around the target of the high frequency sputtering device provided with the magnetic circuit provided with the auxiliary magnet. The figure which shows magnetic flux density distribution (horizontal direction Bx, vertical direction Bz) on the target surface at the time of using the magnetic circuit of Example 2 The schematic sectional drawing around the target of the high frequency sputtering device provided with the magnetic circuit which is not provided with an auxiliary magnet. The figure which shows magnetic flux density distribution (horizontal direction Bx, vertical direction Bz) on the target surface at the time of using the magnetic circuit of Example 3 The figure which shows magnetic flux density distribution (horizontal direction Bx, vertical direction Bz) on the target surface at the time of using the magnetic circuit of Example 4 The figure which shows the relationship between the film-forming speed before heat processing, and the integrated film thickness before heat processing of the film | membrane obtained from the same target The figure which shows the relationship between the refractive index before heat processing, and the integrated film thickness before heat processing of the film | membrane obtained from the same target The figure which shows the relationship between the rate of change of film thickness before and after heat treatment and the integrated film thickness before heat treatment of films obtained from the same target The figure which shows the relationship between the change of the refractive index before and behind heat processing, and the integrated film thickness before heat processing of the film | membrane obtained from the same target

Explanation of symbols

11: Substrate 12: Lower clad 13: Core 14: Upper clad 21: Bi-based multi-component glass film 22: Plasma 23: Target 24: Backing plate 25A: Magnetic circuit with auxiliary magnet 25B: Magnetic circuit without auxiliary magnet 25a: central magnet 25b: outer edge magnet 25c: yoke 25d: auxiliary magnet 25e: non-magnetic auxiliary yoke 26: cathode body 27: anode 28: high frequency power supply

Claims (6)

A dielectric on a substrate under a magnetron magnetic field for applying a high frequency power between a target made of a dielectric material and an anode disposed in the vicinity of the target to increase a plasma density on the target surface A method of forming a dielectric thin film by magnetron sputtering to form a thin film,
A method for forming a dielectric thin film, characterized in that an absolute value of a direct current component of a cathode voltage induced in the target is 50 V or more.   The magnetron magnetic field on the target surface has a magnetic flux density at one position where the direction of the magnetic flux line is horizontal with respect to the target surface, and a plurality of positions where the direction of the magnetic flux line is horizontal. The method for forming a dielectric thin film according to claim 1, wherein the minimum value of the magnetic flux density at each position is 0.005 to 0.025T. The magnetron magnetic field is generated by a set of magnets disposed on the back side of the target;
The set of magnets is disposed between a first magnet disposed at the center of the target, a second magnet disposed at the outer edge, and the first magnet and the second magnet. With an auxiliary magnet,
The ratio of the width of the magnetron magnetic field in which the absolute value of the component perpendicular to the target surface of the magnetic flux density on the target surface is 0.01 T or less to the target width is 10% or more, and The method for forming a dielectric thin film according to claim 1 or 2, wherein the vertical component of the magnetic flux density is a magnetic field having at least one maximum value and minimum value within the range.   The said anode is arrange | positioned adjacently over the perimeter of the said target, and the space | interval of the closest part of the said target and the said anode is 1-10 mm, The any one of Claim 1, 2, or 3 2. A method for forming a dielectric thin film according to 1. Wherein the target is a target made of glass whose main component is Bi ₂ O _3, formation of the dielectric thin film made of a glass film composed mainly of Bi ₂ O ₃ according to any one of claims 1 to 4 Method. A target made of a dielectric material, an anode disposed close to the target, and a magnetron magnetic field that increases the plasma density of the target surface, and a high-frequency voltage is applied between the target and the anode in a reduced pressure atmosphere And a high-frequency magnetron sputtering apparatus for forming a dielectric thin film on a substrate,
When the magnetic circuit for generating the magnetron magnetic field on the target surface has one position where the direction of the magnetic flux lines is horizontal on the target surface, the magnetic flux density at that position is the same, and the position where the direction of the magnetic flux lines is horizontal is A magnetic circuit that generates a magnetic field having a minimum value of magnetic flux density at each position of 0.005 to 0.025 T when there are a plurality of positions;
A high-frequency magnetron sputtering apparatus, wherein an absolute value of a direct current component of a cathode voltage induced at the time of film formation on the target is controlled to be 50 V or more.

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