Sputtering device

Abstract

A sputtering device (100) according to the present disclosure performs sputtering on a substrate (10) disposed in a chamber (110), a sputtering target material (200) being Yb oxide or SiC.

Description

Sputtering equipment

[0001] The present disclosure relates to a sputtering apparatus and the like.

[0002] High-frequency filters are used as high-frequency components in mobile devices such as smartphones. High-frequency filters are required to be compact, lightweight, and have high performance. To meet these requirements, high-frequency filters with resonators made of piezoelectric films have been proposed.

[0003] Known high-frequency filters of this type include SAW (Surface Acoustic Wave) filters and BAW (Bulk Acoustic Wave) filters, of which BAW filters include FBAR (Film Bulk Acoustic Resonator) type filters and SMR (Solid Mounted Resonator) type filters.

[0004] One type of SMR-type BAW filter is known as an acoustic multilayer device having a structure in which an acoustic reflection layer made of an acoustic multilayer film is provided below an acoustic resonator made of a piezoelectric film (see, for example, Patent Document 1). The acoustic reflection layer in the acoustic multilayer device has a laminated structure in which high acoustic impedance layers and low acoustic impedance layers are alternately stacked. The high acoustic impedance layer has a higher acoustic impedance (acoustic impedance value: Z) than the low acoustic impedance layer. The low acoustic impedance layer and the high acoustic impedance layer can be formed by a sputtering method using a sputtering device. The acoustic impedance of each of the low acoustic impedance layer and the high acoustic impedance layer can be calculated by multiplying the density and the sound velocity in each layer.

[0005] The acoustic reflection characteristics of the acoustic reflection layer in an acoustic multilayer device are evaluated by the ratio of the acoustic impedance of the high acoustic impedance layer to the acoustic impedance of the low acoustic impedance layer (hereinafter referred to as the "acoustic impedance ratio" or "acoustic Z ratio"). Specifically, the larger the acoustic impedance ratio, the more the acoustic reflection characteristics of the acoustic reflection layer can be improved. Therefore, if the acoustic impedance of the high acoustic impedance layer can be increased, the acoustic impedance ratio will increase, and the acoustic reflection characteristics of the acoustic reflection layer can be improved.

[0006] Since the acoustic impedance of a high acoustic impedance layer is the product of density and sound velocity, the acoustic impedance of the high acoustic impedance layer can be increased by increasing the density of the high acoustic impedance layer.

[0007] Furthermore, if the resistivity of the high acoustic impedance layer in the acoustic reflection layer is low, the acoustic reflection layer will be electrically coupled to the acoustic resonator adjacent to the acoustic reflection layer, resulting in increased filter loss and deterioration of attenuation characteristics. For this reason, it is preferable that the resistivity of the high acoustic impedance layer is high.

[0008] Thus, as disclosed in Patent Document 1, high acoustic impedance layers in acoustic multilayer devices are required to have high acoustic impedance and high resistivity.

[0009] Japanese Patent Application Laid-Open No. 2007-129391

[0010] The present disclosure aims to provide a thin film suitable for a high acoustic impedance layer, a high-frequency component such as an acoustic multilayer film device having the thin film, a method for manufacturing a high-frequency component such as an acoustic multilayer film device, a sputtering apparatus for depositing the thin film, and a sputtering method for depositing the thin film.

[0011] In order to achieve the above object, the sputtering apparatus according to the present disclosure is a sputtering apparatus that uses Yb oxide or SiC as a target material and sputters onto a substrate placed in a chamber.

[0012] According to the technology of the present disclosure, it is possible to obtain a thin film suitable for a high acoustic impedance layer, a high-frequency component such as an acoustic multilayer film device having the thin film, a method for manufacturing a high-frequency component such as an acoustic multilayer film device, a sputtering apparatus for depositing the thin film, and a sputtering method for depositing the thin film.

[0013] Fig. 1 is a cross-sectional view of an acoustic multilayer device according to an embodiment. Fig. 2 is a flowchart of a method for manufacturing an acoustic multilayer device according to an embodiment. Fig. 3 is a diagram showing the configuration of a sputtering apparatus according to an embodiment. Fig. 4 is a cross-sectional view of an acoustic multilayer device according to a modified example.

[0014] (How One Aspect of the Present Disclosure Was Achieved) Before describing embodiments of the present disclosure, how one aspect of the present disclosure was achieved will be described.

[0015] As described above, the acoustic impedance of a high acoustic impedance layer is the product of density and sound velocity, and therefore, in order to increase the acoustic impedance of a high acoustic impedance layer, it is advisable to increase the density of the high acoustic impedance layer.

[0016] Furthermore, if the resistivity of the high acoustic impedance layer in the acoustic reflection layer is low, the acoustic reflection layer will be electrically coupled to the acoustic resonator adjacent to the acoustic reflection layer, resulting in increased filter loss and deterioration of attenuation characteristics. For this reason, it is preferable that the resistivity of the high acoustic impedance layer is high.

[0017] From this perspective, the present inventors have conducted various studies on a thin film suitable for a high acoustic impedance layer, an acoustic multilayer film device having the high acoustic impedance layer, a method for manufacturing high frequency components such as an acoustic multilayer film device, a sputtering apparatus for depositing the thin film, and a sputtering method for depositing the thin film, etc. For example, the present inventors have studied a sputtering apparatus etc. that can obtain a Yb oxide film or SiC film that has high density and high resistivity, and have arrived at one embodiment of a sputtering apparatus according to the present disclosure.

[0018] Specifically, one aspect of the sputtering apparatus according to the present disclosure is a sputtering apparatus that uses Yb oxide or SiC as a target material to sputter onto a substrate placed in a chamber.

[0019] This makes it possible to obtain a Yb oxide film or SiC film having high density and high resistivity.

[0020] In one aspect of the sputtering apparatus according to the present disclosure, the sputtering apparatus is a sputtering apparatus for manufacturing an acoustic multilayer film device including the substrate, an acoustic reflection layer including a low acoustic impedance layer and a high acoustic impedance layer having an acoustic impedance higher than that of the low acoustic impedance layer, and an acoustic resonator laminated on the acoustic reflection layer, and the high acoustic impedance layer is preferably formed using the Yb oxide or the SiC as a target material.

[0021] This allows the high-density Yb oxide film or SiC film to increase the acoustic impedance of the high acoustic impedance layer, thereby obtaining a high acoustic impedance layer with high acoustic impedance and high resistivity, which improves the acoustic reflection characteristics of the acoustic reflection layer, thereby obtaining an acoustic multilayer film device with excellent acoustic reflection characteristics.

[0022] In one aspect of the sputtering apparatus according to the present disclosure, the target material is YbO Ｘ , Yb ２ O ３ It would be good if that were the case.

[0023] YbO Ｘ membrane or Yb ２ O ３ The high density of the film allows the high acoustic impedance of the high acoustic impedance layer to be increased. This makes it easy to obtain a high acoustic impedance layer with high acoustic impedance and high resistivity. Furthermore, the high acoustic impedance layer can be formed safely with low risk of fire.

[0024] In one aspect of the sputtering apparatus according to the present disclosure, the oxygen partial pressure in the chamber is 5×10 －５It is preferable that the pressure can be maintained at or below Pa.

[0025] This reduces the amount of oxygen in the chamber when depositing the Yb oxide film or SiC film, making it possible to deposit a Yb oxide film or SiC film with a low oxygen ratio (i.e., a high film density).

[0026] In one aspect of the sputtering apparatus according to the present disclosure, the water pressure in the chamber is 5×10 －５ It is preferable that the pressure can be maintained at or below Pa.

[0027] This reduces the amount of moisture in the chamber when depositing the Yb oxide film or SiC film, thereby preventing oxygen contained in the moisture from bonding to the Yb oxide film or SiC film, increasing the oxygen ratio in the Yb oxide film or SiC film and reducing the density of the Yb oxide film or SiC film, which means that a Yb oxide film or SiC film with a higher film density can be deposited.

[0028] In one aspect of the sputtering apparatus according to the present disclosure, the target material may be Yb oxide, and the pressure in the chamber may be 2 Pa or more.

[0029] This makes it possible to obtain a Yb oxide film or SiC film having high density and low stress.

[0030] In addition, in one aspect of the sputtering apparatus according to the present disclosure, the distance between the substrate and the target material may be set to 70 mm or less.

[0031] This makes it possible to obtain a Yb oxide film or SiC film with even lower stress.

[0032] In one aspect of the sputtering apparatus according to the present disclosure, the chamber may be filled with a rare gas.

[0033] This makes it possible to easily form a Yb oxide film or SiC film having high density and high resistivity. In particular, by performing sputtering with the chamber filled with only a rare gas, the amount of oxygen in the chamber is reduced, making it possible to easily form a Yb oxide film or SiC film with a low oxygen ratio (i.e., a high film density).

[0034] (Embodiments) Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, component placement and connection configurations, steps (processes), and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present disclosure will be described as optional components.

[0035] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, the scales and the like do not necessarily match in each figure. In each figure, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0036] Furthermore, in this specification, the terms "above," "up," "below," and "below" do not refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in a stacked configuration. Furthermore, the terms "above," "up," "below," and "below" are used not only when two components are arranged with a gap between them and another component is present between them, but also when two components are arranged in contact with each other.

[0037] [Acoustic Multilayer Device] First, the configuration of an acoustic multilayer device 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the acoustic multilayer device 1 according to an embodiment.

[0038] 1, the acoustic multilayer device 1 includes a substrate 10, an acoustic reflection layer 20 (acoustic reflection portion), and an acoustic resonator 30 (acoustic resonator portion) having a piezoelectric film. The acoustic multilayer device 1 in this embodiment is an SMR-type BAW filter, and is capable of reflecting elastic waves by the acoustic reflection layer 20 located below the acoustic resonator 30.

[0039] The substrate 10 is a support substrate that supports the acoustic reflection layer 20 and the acoustic resonator 30. The substrate 10 is also a base substrate on which a thin film that constitutes the acoustic reflection layer 20 is formed by sputtering. The substrate 10 may be, for example, a silicon substrate made of silicon. Note that a dielectric surface layer made of silicon dioxide may be formed on the surface of the substrate 10 made of a silicon substrate. Note that the substrate 10 is not limited to a silicon substrate.

[0040] The acoustic reflection layer 20 is located on the substrate 10. Specifically, the acoustic reflection layer 20 is laminated on the substrate 10. The acoustic reflection layer 20 is also located below the acoustic resonator 30. In other words, the acoustic reflection layer 20 is located between the substrate 10 and the acoustic resonator 30.

[0041] The acoustic reflection layer 20 is an acoustic Bragg reflector including a high acoustic impedance layer 21 (high Z layer) and a low acoustic impedance layer 22 (low Z layer). The high acoustic impedance layer 21 is a layer with a higher acoustic impedance than the low acoustic impedance layer 22. In other words, the low acoustic impedance layer 22 is a layer with a lower acoustic impedance than the high acoustic impedance layer 21. The high acoustic impedance layer 21 preferably has a high acoustic impedance (= density × sound speed), and the low acoustic impedance layer 22 preferably has a low acoustic impedance. The film thicknesses of the high acoustic impedance layer 21 and the low acoustic impedance layer 22 are not particularly limited, but are, for example, one-fourth of the acoustic wavelength.

[0042] The acoustic reflection layer 20 has a laminated structure in which high acoustic impedance layers 21 and low acoustic impedance layers 22 are repeatedly stacked. The acoustic reflection layer 20 has one or more laminated films, each of which is a pair of a high acoustic impedance layer 21 and a low acoustic impedance layer 22. In this embodiment, the acoustic reflection layer 20 is a multilayer film (acoustic multilayer film) in which multiple laminated films, each of which is a pair of a high acoustic impedance layer 21 and a low acoustic impedance layer 22, are stacked. In this manner, the acoustic reflection layer 20 is configured with multiple pairs of a high acoustic impedance layer 21 and a low acoustic impedance layer 22, and the high acoustic impedance layers 21 and the low acoustic impedance layers 22 are stacked alternately. Specifically, the acoustic reflection layer 20 has four layers (four pairs) of laminated films, each of which is a pair of a high acoustic impedance layer 21 and a low acoustic impedance layer 22. By increasing the number of pairs of a high acoustic impedance layer 21 and a low acoustic impedance layer 22, the acoustic reflection characteristics can be improved.

[0043] In the present embodiment, the bottom layer of the acoustic reflection layer 20 is the high acoustic impedance layer 21, and the top layer of the acoustic reflection layer 20 is the low acoustic impedance layer 22, but this is not limiting. For example, the bottom layer of the acoustic reflection layer 20 may be the low acoustic impedance layer 22, and the top layer of the acoustic reflection layer 20 may be the high acoustic impedance layer 21.

[0044] The high acoustic impedance layer 21 contains Yb (ytterbium) as a composition. In this embodiment, the high acoustic impedance layer 21 contains Yb oxide, which is an oxide of Yb. Specifically, the high acoustic impedance layer 21 contains YbO Ｘ and / or Yb ２ O ３ It is composed of YbO Ｘ is Yb ２ O ３ and a Yb oxide film (ytterbium oxide film) having a different oxygen ratio. For example, YbO Ｘ is Yb ２ O ３ In this case, the YbO ＸThe oxygen ratio X in the above formula is 0<X<1.5, and more preferably 1<X1.5. Ｘ and Yb ２ O ３ In this case, YbO Ｘ Regarding x, it is acceptable for some values ​​to be in the range of 1<x<1.5.

[0045] The high acoustic impedance layer 21 is not limited to a Yb film (ytterbium film) containing Yb as a composition, such as a Yb oxide film, etc. For example, the high acoustic impedance layer 21 may be a SiC film made of SiC (silicon carbide).

[0046] The low acoustic impedance layer 22 contains aluminum (Al), silicon (Si), an oxide of aluminum, or an oxide of silicon. In this embodiment, the low acoustic impedance layer 22 is made of an oxide of silicon. Specifically, the low acoustic impedance layer 22 is made of SiO ２ It is composed of:

[0047] The acoustic resonator 30 is an acoustic vibrator located on the acoustic reflection layer 20. Specifically, the acoustic resonator 30 is laminated on the acoustic reflection layer 20.

[0048] The acoustic resonator 30 has a lower electrode 31, a piezoelectric layer 32 located on the lower electrode 31, and an upper electrode 33 located on the piezoelectric layer 32. The piezoelectric layer 32 is disposed between the lower electrode 31 and the upper electrode 33. The piezoelectric layer 32 is a piezoelectric film made of a piezoelectric material such as zinc oxide or aluminum nitride. The acoustic resonator 30 may include a crystalline lens.

[0049] [Method for Manufacturing Acoustic Multilayer Device] Next, a method for manufacturing the acoustic multilayer device 1 according to the embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 2 is a flowchart of the method for manufacturing the acoustic multilayer device 1 according to the embodiment.

[0050] As shown in FIG. 2, the method for manufacturing the acoustic multilayer device 1 includes an acoustic reflection layer forming step S10 and an acoustic resonator forming step S20.

[0051] 1, in the acoustic reflection layer forming step S10, an acoustic reflection layer 20 is formed on a substrate 10. Specifically, a high acoustic impedance layer 21 and a low acoustic impedance layer 22 are formed on the substrate 10 as the acoustic reflection layer 20.

[0052] As shown in FIG. 2, the acoustic reflection layer forming step S10 includes a high acoustic impedance layer forming step S11 for forming a high acoustic impedance layer 21 and a low acoustic impedance layer forming step S12 for forming a low acoustic impedance layer 22.

[0053] In this case, since the bottom layer of the acoustic reflection layer 20 is the high acoustic impedance layer 21, the high acoustic impedance layer 21 is first formed on the substrate 10 (high acoustic impedance layer forming step S11).

[0054] In the high acoustic impedance layer forming step S11, the high acoustic impedance layer 21 is formed by sputtering. In this embodiment, the high acoustic impedance layer 21 is made of Yb oxide, so that the high acoustic impedance layer 21 made of Yb oxide can be formed by sputtering the substrate 10 using Yb oxide as a target material. In this case, the target material made of Yb oxide is YbO Ｘ and / or Yb ２ O ３ The target material is YbO Ｘ and / or Yb ２ O ３ By using YbO Ｘ and / or Yb ２ O ３ The high acoustic impedance layer 21 can be formed from the above.

[0055] When the high acoustic impedance layer 21 is made of SiC, the high acoustic impedance layer 21 made of SiC can be formed by sputtering the substrate 10 using SiC as a target material.

[0056] After forming one high acoustic impedance layer 21, a low acoustic impedance layer 22 is formed on the substrate 10 on which the high acoustic impedance layer 21 has been formed (low acoustic impedance layer forming step S12). Specifically, the low acoustic impedance layer 22 is formed on the high acoustic impedance layer 21.

[0057] In the low acoustic impedance layer forming step S12, the low acoustic impedance layer 22 is formed by sputtering. In this embodiment, the low acoustic impedance layer 22 is made of SiO ２ Since it is composed of SiO ２ is used as a target material to perform sputtering on the substrate 10 on which the high acoustic impedance layer 21 is formed, ２ The low acoustic impedance layer 22 can be formed from the above.

[0058] The low acoustic impedance layer 22 is made of Al, Al ２ O ３ Or when it is composed of Si, Al, Al ２ O ３ Alternatively, Si is used as a target material and sputtering is performed on the substrate 10 on which the high acoustic impedance layer 21 is formed. As a result, Al, Al ２ O ３ Alternatively, the low acoustic impedance layer 22 can be made of Si.

[0059] After forming one low acoustic impedance layer 22 on the high acoustic impedance layer 21, the high acoustic impedance layers 21 and the low acoustic impedance layers 22 are then alternately formed one by one as needed. That is, the high acoustic impedance layer forming step S11 and the low acoustic impedance layer forming step S12 are alternately repeated. This allows the formation of an acoustic reflection layer 20 in which the high acoustic impedance layers 21 and the low acoustic impedance layers 22 are alternately stacked one by one.

[0060] In this embodiment, the acoustic reflection layer 20 is configured such that four high acoustic impedance layers 21 and four low acoustic impedance layers 22 are alternately provided, and therefore the high acoustic impedance layer forming step S11 and the low acoustic impedance layer forming step S12 are alternately repeated four times.

[0061] When the bottom layer of the acoustic reflection layer 20 is a low acoustic impedance layer 22 instead of a high acoustic impedance layer 21, the low acoustic impedance layer 22 is first formed on the substrate 10, and then the high acoustic impedance layer 21 is formed on the low acoustic impedance layer 22, and this process is repeated alternately multiple times. In this way, the acoustic reflection layer 20 consisting of a laminated film of the low acoustic impedance layer 22 and the high acoustic impedance layer 21 can be formed.

[0062] After forming the acoustic reflection layer 20 on the substrate 10, the acoustic resonator 30 is formed on the acoustic reflection layer 20 (acoustic resonator formation step S20 in FIG. 2 ). In this embodiment, the uppermost layer of the acoustic reflection layer 20 is the low acoustic impedance layer 22, so the acoustic resonator 30 is formed on the uppermost low acoustic impedance layer 22. Specifically, a lower electrode 31, a piezoelectric layer 32, and an upper electrode 33 are sequentially formed on the acoustic reflection layer 20, and the laminated film of the lower electrode 31, the piezoelectric layer 32, and the upper electrode 33 is patterned into a predetermined shape. This allows the acoustic multilayer film device 1 having the structure shown in FIG. 1 to be fabricated.

[0063] [Sputtering Method and Sputtering Apparatus] The high acoustic impedance layer 21 and the low acoustic impedance layer 22 in the acoustic multilayer film device 1 can be formed by sputtering using a sputtering apparatus.

[0064] The configuration of the sputtering apparatus 100 used to form the high acoustic impedance layer 21 and the low acoustic impedance layer 22 will be described below with reference to Fig. 3. Fig. 3 is a diagram showing the configuration of the sputtering apparatus 100 according to an embodiment.

[0065] The sputtering apparatus 100 is a film formation apparatus that forms a thin film by magnetron sputtering, and as shown in FIG. 3, is equipped with a chamber 110, a substrate holding unit 120 that holds a substrate 10, a target holding unit 130 that holds a target material 200 (target), and a gas supply unit 140 that supplies gas into the chamber 110.

[0066] The chamber 110 is a reaction chamber for sputtering. The chamber 110 is a vacuum chamber. The chamber 110 can be depressurized to a vacuum state by evacuating the chamber 110 with a vacuum pump 151. A cryopump, a turbomolecular pump, or the like can be used as the vacuum pump 151. The degree of vacuum in the chamber 110 can be adjusted to a desired pressure by a valve 152. For example, the degree of vacuum in the chamber 110 can be controlled to a desired pressure by changing the opening / closing ratio of the valve 152.

[0067] The substrate holding unit 120 is disposed within the chamber 110. In this embodiment, the substrate holding unit 120 is a stage that can move in both the vertical and horizontal directions. The substrate holding unit 120 can also rotate horizontally around a vertical axis.

[0068] The substrate holding part 120 is disposed opposite the target material 200 and the target holding part 130. The substrate 10 placed on the substrate holding part 120 is fixed to the substrate holding part 120 by a fixing jig 121. The fixing means for the substrate 10 may be an electrostatic chuck. When the high acoustic impedance layer 21 and the low acoustic impedance layer 22 are formed, the substrate holding part 120, which serves as a stage, serves as an anode.

[0069] The target holder 130 is disposed within the chamber 110. In this embodiment, the target holder 130 is a backing plate. The target holder 130 is disposed opposite the substrate holder 120. Therefore, the substrate 10 held by the substrate holder 120 and the target material 200 held by the target holder 130 face each other. When the high acoustic impedance layer 21 and the low acoustic impedance layer 22 are formed, the target holder 130 serves as a cathode.

[0070] The target material 200 held by the target holder 130 is a material for sputtering. When the high acoustic impedance layer 21 is made of Yb oxide, Yb oxide is used as the target material 200. For example, YbO Ｘ membrane or Yb ２ O ３ When forming a film, the target material 200 is YbO Ｘ and / or Yb ２ O ３ The low acoustic impedance layer 22 is made of SiO ２ When forming a film, Si is used as the target material 200 .

[0071] The gas supply unit 140 is a gas supply source that supplies a gas required for sputtering (sputtering gas) into the chamber 110. The gas supply unit 140 is composed of a gas source such as a gas cylinder and a flow rate controller such as a mass flow controller, and can supply the gas required for sputtering into the chamber 110 at a constant rate.

[0072] The gas supply unit 140 supplies an inert gas into the chamber 110 as one of the gases required for sputtering. Specifically, the gas supply unit 140 supplies a rare gas such as Ar, He, Ne, Kr, or Xe into the chamber 110 as the inert gas. Therefore, when the high acoustic impedance layer 21 and the low acoustic impedance layer 22 are formed, the chamber 110 is filled with the rare gas. Among rare gases, Ar is particularly preferred as the rare gas because it is inexpensive and has a high sputtering yield. In this embodiment, Ar is used as the rare gas when forming the high acoustic impedance layer 21 and the low acoustic impedance layer 22.

[0073] The gas supply unit 140 may supply not only a rare gas but also a reactive gas as the gas required for sputtering. In this case, the gas supply unit 140 supplies a mixed gas of a rare gas and a reactive gas. For example, when SiO ２ When forming the film, O is used as a reaction gas. ２ Gas is supplied into the chamber 110. Specifically, O 2 is supplied from the gas supply unit 140 to the chamber 110. ２ A mixture of gas and rare gas is supplied.

[0074] A magnetic circuit 170 may be disposed outside the chamber 110 so as to face the target material 200. The magnetic circuit 170 allows the plasma generated within the chamber 110 to be concentrated on the surface of the target material 200.

[0075] Next, a sputtering method for forming the high acoustic impedance layer 21 by sputtering the substrate 10 using the sputtering apparatus 100 according to the embodiment will be described.

[0076] First, the substrate 10 and the target material 200 are set in the chamber 110. Specifically, the substrate 10 is set on the substrate holder 120, and the target material 200 is set on the target holder 130. The substrate 10 and the target material 200 are set so as to face each other. In this embodiment, since the substrate holder 120 is provided below the target holder 130, the substrate 10 is set below the target material 200.

[0077] At this time, it is preferable that the distance between the substrate 10 and the target material 200 (TS distance) is set within a predetermined range. The distance between the substrate 10 and the target material 200 can be adjusted, for example, by vertically moving the substrate holder 120 that holds the substrate 10. Note that the target holder 130 that holds the target material 200 may be configured to be able to adjust the distance between the substrate 10 and the target material 200 by vertically moving it.

[0078] When forming the high acoustic impedance layer 21, the target material 200 is, for example, YbO Ｘ or Yb ２ O ３ Yb oxides such as YbO or SiC can be used. Ｘ The target material 200 is composed of Yb ２ O ３ For example, the target material 200 can be made of Yb ２ O ３ By subjecting the target material 200 made of YbO to a process that changes the oxygen ratio, Ｘ As an example, a target material 200 made of YbO Ｘ is Yb ２ O ３ In this case, 0<X<1.5, and more preferably 1<X1.5<.

[0079] YbO as the target material 200 Ｘ or Yb ２ O ３ By using YbO 2 , the risk of ignition is low and the high acoustic impedance layer 21 can be safely formed. This is because Yb powder is energetically unstable and may react with oxygen and ignite. Ｘ Membrane and Yb ２ O ３ The same risk is considered for the YbO film. Ｘ or Yb ２ O ３By using the target material 200, the high acoustic impedance layer 21 can be safely deposited with low risk of ignition.

[0080] Next, the vacuum pump 151 is operated to reduce the pressure inside the chamber 110 so that it is in a vacuum state. After the chamber 110 reaches a predetermined vacuum level, Ar is supplied into the chamber 110 from the gas supply unit 140 as a rare gas, and the opening of the valve 152 is adjusted so that the chamber 110 reaches a predetermined pressure (gas pressure).

[0081] At this time, it is preferable that the pressure inside the chamber 110 filled with the rare gas is within a predetermined range. Also, it is preferable that the oxygen partial pressure and water pressure inside the chamber 110 are also below predetermined values. In other words, it is preferable that the sputtering apparatus 100 is capable of maintaining the oxygen partial pressure and water pressure inside the chamber 110 below predetermined values. In this case, since a cryopump absorbs water more than a turbomolecular pump, it is preferable to use a cryopump as the vacuum pump 151. In other words, by using a cryopump as the vacuum pump 151, it is possible to easily maintain the water pressure inside the chamber 110 below predetermined values.

[0082] Next, a voltage is applied to the target holder 130, which is a backing plate, by the power supply 160. As a result, Ar in the chamber 110 is ionized to generate Ar ions, and plasma is generated in the chamber 110. The Ar ions collide with the target material 200, causing elements constituting the target material 200 to be ejected from the target material 200 and deposited on the substrate 10. In other words, a thin film composed of the elements constituting the target material 200 is formed on the substrate 10.

[0083] For example, the target material 200 may be YbO Ｘ and Yb ２ O ３ By using Yb oxide or SiC, it is possible to form a high acoustic impedance layer 21 made of a thin film of Yb oxide or SiC on the substrate 10 .

[0084] The low acoustic impedance layer 22 can be formed by using the target material 200 for forming the low acoustic impedance layer 22. For example, by using Si as the target material 200, SiO ２ Thin film (SiO ２ A low acoustic impedance layer 22 made of a SiO 2 film can be deposited on the substrate 10 or the high acoustic impedance layer 21 .

[0085] [Example (Study of Film Materials and Film Forming Conditions)] As described above, the acoustic reflection characteristics of the acoustic reflecting layer 20 in the acoustic multilayer film device 1 can be improved as the acoustic impedance ratio (acoustic Z ratio), which is the ratio of the acoustic impedance of the high acoustic impedance layer 21 to the acoustic impedance of the low acoustic impedance layer 22, increases. For this reason, it is preferable that the acoustic impedance of the high acoustic impedance layer 21 is high.

[0086] Furthermore, if the resistivity of the high acoustic impedance layer 21 is low, the acoustic reflection layer 20 and the acoustic resonator 30 are electrically coupled to each other, increasing filter loss and deteriorating attenuation characteristics, and therefore it is preferable that the resistivity of the high acoustic impedance layer 21 is high. For example, it is preferable that the high acoustic impedance layer 21 has high insulating properties.

[0087] Therefore, the inventors have investigated film materials for the high acoustic impedance layer 21 having high acoustic impedance and high resistivity, and have also conducted various experiments to examine the film formation conditions for the film materials.The results of these investigations will be described below.

[0088] [Study on Film Materials] First, the film materials used for the high acoustic impedance layer 21 were studied, and the results of the study will be described. ２、 Ta ２ O ５ , YbO Ｘ , Yb ２ O ３ The acoustic Z ratios of the low acoustic impedance layer 22 (SiO ２The resistivity of YbO is the value at a temperature of 1000 Kelvin. Ｘ The density, Young's modulus, sound velocity, acoustic impedance, and resistivity of YbO (X=1) and Yb ２ O ３ (X=1.5).

[0089]

[0090] As can be seen from Table 1, YbO, Yb ２ O ３ and SiC is Ta ２ O ５ Specifically, YbO, Yb ２ O ３ By using SiC, the acoustic impedance and resistivity shown in Table 1 can be obtained.

[0091] Also, YbO, Yb ２ O ３ and SiC have a high Young's modulus, and it is believed that a film with a dense film structure (high density) can be obtained. ２ O ３ The Young's modulus is higher than that of Yb ２ O ３ However, by scattering a large amount of YbO, a film with a dense film structure can be obtained.

[0092] [Experiment 1] From the results in Table 1 above, it can be seen that the oxygen ratios of Yb ２ O ３ film and YbO Ｘ From this result, the inventors have found that when a Yb oxide film made of Yb oxide is formed by sputtering, the density of the Yb film may differ depending on the oxygen partial pressure during sputtering.

[0093] Therefore, the inventors conducted Experiment 1 using the sputtering apparatus 100 to form a Yb film (Yb oxide film) made of Yb oxide by varying the oxygen ratio of the supply gas supplied into the chamber 110, and the results of the experiment and the investigation will be described below.

[0094] In Experiment 1, Yb films were formed by varying the oxygen ratio in the Ar gas supplied into the chamber 110. Specifically, the oxygen ratio in the supply gas was 0% (i.e., the supply gas was only Ar gas), and the oxygen ratios in the supply gas were 2.44% and 20% (i.e., the supply gas was Ar gas and O ２ The results are shown in Table 2.

[0095] The film formation conditions for Experiment 1 were a pressure in the chamber 110 of 0.5 Pa, a power of 1.4 kW, a distance between the substrate 10 and the target material 200 (TS distance) of 70 mm, and Ar gas alone supplied to the chamber 110. The target film thickness of each film was 100 nm, and a 4-inch silicon wafer with a thickness of 525 μm was used as the substrate 10. The density (film density) of the Yb film was measured by XRR (X-ray reflectance).

[0096]

[0097] From Table 2, it can be seen that a high density Yb film can be formed by reducing the oxygen ratio of the supply gas supplied into the chamber 110. In particular, it can be seen that it is better not to include oxygen in the supply gas, and that the supply gas should be only a rare gas. In other words, it is better not to add oxygen gas to the supply gas. In this way, by not adding oxygen gas to the supply gas, the oxygen in the chamber 110 is reduced, so it is better to use Yb as the target material 200. ２ O ３ Even if Yb is used, the surface of the target material 200 turns black during sputtering. ２ O ３ is YbO Ｘ and Yb ２ O ３ YbO film with a lower oxygen ratio (i.e., a higher density) Ｘ From the above, the oxygen partial pressure in the chamber 110 is 5×10, which is the detection limit of the mass spectrometer. －５ It is preferable that the temperature is 0.1 Pa or less.

[0098] [Experiment 2] Furthermore, since the components (target material 200, substrate 10, etc.) placed in the chamber 110 may contain moisture from the atmosphere, if the moisture is released during sputtering and the oxygen contained in the moisture combines with Yb, it is thought that the oxygen ratio in the Yb film, which is a Yb oxide film, will increase, which may result in a decrease in the density of the Yb film. From this, the inventors have discovered that when a Yb film made of Yb oxide is formed by sputtering, the density of the Yb film may differ depending on the moisture pressure during sputtering.

[0099] Therefore, the inventors conducted Experiment 3 in which a Yb film (Yb oxide film) made of Yb oxide was formed by varying the water pressure in the chamber 110 during sputtering, and the results of the experiment and investigation will be described below.

[0100] In Experiment 2, the water pressure in the chamber 110 during sputtering was set to 2×10 －５ Pa, 4.3 x 10 －５ Pa and 15 x 10 －５ The film deposition conditions for Experiment 3 were the same as those for Experiment 1.

[0101]

[0102] From Table 3, it can be seen that the density of the Yb film increases as the water pressure in the chamber 110 decreases. This is because the YbO Ｘ As shown in Table 3, the water pressure is 2 × 10 －５ Pa and 4.3 × 10 －５ Since the density of the Yb film does not change significantly between the cases of 5 Pa and 10 Pa, the water pressure is 5 × 10 －５ This results in a density of approximately 9.3 g / cm ３ Dense film structure of YbO Ｘ It can be seen that a film can be obtained.

[0103] [Experiment 3] The inventors also considered that the quality of the Yb film might also be affected by the pressure in the chamber 110 and the distance between the substrate 10 and the target material 200 (TS distance) when forming the Yb film by sputtering.

[0104] Therefore, the inventors have tried to obtain a Yb film by varying the pressure in the chamber 110 and the distance between the TS during sputtering. ２ O ３ The results of the experiment and the investigation are explained below. ２ O ３ The density (film density) and residual stress (film stress) of the film were measured as film quality. ２ O ３ The film density was measured by XRR as described above. Residual stress was calculated by evaluating the difference in warpage before and after film formation. The film formation conditions in Experiment 3 were the same as those in Experiment 1, but the pressure was changed when conducting the pressure dependency experiment, and the TS distance was changed when conducting the TS distance dependency experiment.

[0105] In the experiment on the dependency of the TS distance, the TS distance was changed to 60 mm, 70 mm, 90 mm, and 110 mm. In the experiment on the dependency of the pressure, when the TS distance was 60 mm, the pressure inside the chamber 110 was changed to 0.25 Pa, 0.5 Pa, 1 Pa, and 2 Pa, when the TS distance was 70 mm, the pressure inside the chamber 110 was changed to 0.5 Pa, 1 Pa, and 2 Pa, and when the TS distance was 110 mm, the pressure inside the chamber 110 was changed to 0.25 Pa, 0.5 Pa, 1 Pa, and 2 Pa. The results are shown in Table 4.

[0106]

[0107] From the "pressure dependency" in Table 4, it can be seen that the pressure in the chamber 110 is set to 2 Pa or more, and the Yb ２ O ３ The density of the film is 9.3 g / cm ３ The above can be done, and Yb ２ O ３It can be seen that the compressive stress of the film can be reduced to 1000 MPa or less. In particular, the compressive stress can be reduced to 700 MPa or less by setting the pressure to 2 Pa or more. Specifically, it can be seen that by setting the pressure to 2 Pa or more, the compressive stress can be dramatically reduced to less than half compared to when the pressure is 1 Pa or less. In this way, by performing sputtering using Yb oxide as the target material with the pressure in the chamber 110 set to 2 Pa or more, it is possible to obtain Yb oxide having high density (i.e., a dense film structure) and low stress (low compressive stress). ２ O ３ A film can be obtained.

[0108] Furthermore, from the "Tsubasa distance dependency" in Table 4, it can be seen that the compressive stress is significantly reduced by setting the pressure to 2 Pa or more and the TS distance to 70 mm or less. Therefore, by setting the TS distance to 70 mm or less and performing sputtering using Yb oxide as the target material, it is possible to obtain Yb with even lower stress. ２ O ３ A film can be obtained.

[0109] The lower limit of the TS distance is not particularly limited, but is preferably Yb ２ O ３ From the viewpoint of stably forming a film, the distance between the TSs is preferably 50 mm or more.

[0110] [Summary of Experiment] As described above, YbO Ｘ or Yb ２ O ３ By sputtering the Yb oxide as the target material 200 onto the substrate 10 using the sputtering device 100, YbO having high density and high resistivity can be obtained. Ｘ membrane or Yb ２ O ３ A Yb film can be obtained.

[0111] The acoustic impedance of the high acoustic impedance layer 21 of the acoustic reflection layer 20 in the acoustic multilayer device 1 is the product of density and sound velocity, so the higher the density of the high acoustic impedance layer 21, the higher the acoustic impedance. Ｘ membrane or Yb ２ O ３ Because of its high film density, YbO is used as the high acoustic impedance layer 21.Ｘ membrane or Yb ２ O ３ By using the film, it is possible to obtain the high acoustic impedance layer 21 having high acoustic impedance and high resistivity, which makes it possible to increase the acoustic impedance ratio and improve the acoustic reflection characteristics of the acoustic reflection layer 20.

[0112] Also, as mentioned above, YbO Ｘ membrane or Yb ２ O ３ The film can be formed by a sputtering method under predetermined film formation conditions using the sputtering apparatus 100. Specifically, by sputtering the substrate 10 with Yb oxide as the target material 200 under a condition where the pressure in the chamber 110 filled with a rare gas is set to 2 Pa or more, a Yb oxide film having not only high density but also low stress can be formed. ２ O ３ film or YbO Ｘ A film can be obtained.

[0113] This low stress Yb ２ O ３ film or YbO Ｘ By applying this film to the high acoustic impedance layer 21, a BAW filter with an SMR structure having high performance and high reliability can be realized. That is, in the acoustic multilayer film device 1, which is a BAW filter with an SMR structure, the acoustic reflection layer 20 has a structure in which high acoustic impedance layers 21 and low acoustic impedance layers 22 are alternately stacked multiple times. However, if the compressive stress of the high acoustic impedance layer 21 is high, the substrate 10 on which the acoustic reflection layer 20 is formed will warp. As a result, the performance and reliability of the acoustic multilayer film device 1 will deteriorate. In contrast, as described above, the low compressive stress of the high acoustic impedance layer 21 can prevent the substrate 10 from warping. This prevents a deterioration in the performance and reliability of the acoustic multilayer film device 1.

[0114] (Variations) The acoustic multilayer film device, the method for manufacturing the acoustic multilayer film device, the sputtering apparatus, the sputtering method, etc. according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to the above embodiments.

[0115] For example, in the above embodiment, the acoustic multilayer film device 1 is provided with one acoustic resonator 30. However, this is not limiting, and the acoustic multilayer film device 1 may have multiple acoustic resonators 30. Specifically, as shown in FIG. 4 , the acoustic multilayer film device 1A may have two acoustic resonators 30. In FIG. 4 , each of the two acoustic resonators 30 has the same structure and is provided side by side on the acoustic reflection layer 20. The two acoustic resonators 30 are electrically independent. Note that multiple acoustic resonators 30 can be formed by patterning a laminated film of a lower electrode 31, a piezoelectric layer 32, and an upper electrode 33. Specifically, multiple acoustic resonators 30 can be formed by patterning the laminated film of the lower electrode 31, the piezoelectric layer 32, and the upper electrode 33 so as to separate it into multiple parts.

[0116] In addition, the present disclosure also includes forms obtained by applying various modifications that would occur to those skilled in the art to the above-described embodiments and modifications, and forms realized by arbitrarily combining the components and functions of the embodiments and modifications within the scope of the present disclosure. The present disclosure also includes any combination of two or more claims from the multiple claims set forth in the claims at the time of filing, provided that they are not technically inconsistent. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of the technically inconsistent claims, the present disclosure also includes any combination of all claims included in that multiple claim or multiple multiple multiple claim.

[0117] The technology disclosed herein can be applied to thin films used in high-frequency components such as acoustic multilayer devices, high-frequency components such as acoustic multilayer devices having such thin films, manufacturing methods for high-frequency components such as acoustic multilayer devices, sputtering apparatuses for depositing thin films used in acoustic multilayer devices, and sputtering methods for depositing such thin films.

[0118] 1, 1A Acoustic multilayer device 10 Substrate 20 Acoustic reflection layer 21 High acoustic impedance layer 22 Low acoustic impedance layer 30 Acoustic resonator 31 Lower electrode 32 Piezoelectric layer 33 Upper electrode 100 Sputtering apparatus 110 Chamber 120 Substrate holder 121 Fixing jig 130 Target holder 140 Gas supply unit 151 Vacuum pump 152 Valve 160 Power supply 170 Magnetic circuit 200 Target material

Claims

1. A sputtering device that uses Yb oxide or SiC as a target material to sputter onto a substrate placed in a chamber.

2. The sputtering apparatus according to claim 1 is a sputtering apparatus for manufacturing an acoustic multilayer device comprising: the substrate; an acoustic reflection layer including a low acoustic impedance layer and a high acoustic impedance layer having an acoustic impedance higher than that of the low acoustic impedance layer; and an acoustic resonator laminated on the acoustic reflection layer; and the high acoustic impedance layer is formed using the Yb oxide or the SiC as a target material.

3. The target material is YbO Ｘ , Yb ２ O ３ 3. The sputtering apparatus according to claim 1, wherein:

4. The oxygen partial pressure in the chamber is 5 x 10 －５ 4. The sputtering apparatus according to claim 1, wherein the pressure can be maintained at or below Pa.

5. The water pressure in the chamber is 5 x 10 －５ 5. The sputtering apparatus according to claim 1, wherein the pressure can be maintained at or below Pa.

6. The sputtering apparatus according to any one of claims 1 to 5, wherein the target material is Yb oxide, and the pressure inside the chamber is 2 Pa or higher.

7. A sputtering apparatus according to any one of claims 1 to 6, wherein the distance between the substrate and the target material is set to 70 mm or less.

8. The sputtering apparatus according to any one of claims 1 to 7, wherein the chamber is filled with a rare gas.

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