WO2022201627A1 - 接合体およびその製造方法 - Google Patents
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- WO2022201627A1 WO2022201627A1 PCT/JP2021/041871 JP2021041871W WO2022201627A1 WO 2022201627 A1 WO2022201627 A1 WO 2022201627A1 JP 2021041871 W JP2021041871 W JP 2021041871W WO 2022201627 A1 WO2022201627 A1 WO 2022201627A1
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- piezoelectric material
- material substrate
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Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
- H10N30/072—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies
- H10N30/073—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies by fusion of metals or by adhesives
Definitions
- the present invention relates to a bonded body of a piezoelectric material substrate and a support substrate made of silicon.
- Acoustic wave devices such as surface acoustic wave devices that can function as filter elements and oscillators used in mobile phones, Lamb wave elements using piezoelectric thin films, and thin film resonators (FBAR: Film Bulk Acoustic Resonator).
- FBAR Film Bulk Acoustic Resonator
- a device is known in which a support substrate and a piezoelectric material substrate for propagating surface acoustic waves are bonded together, and a comb-shaped electrode capable of exciting surface acoustic waves is provided on the surface of the piezoelectric material substrate. .
- Non-Patent Document 1 a SAW filter using a SOI (Silicon - on-Insulator, a structure in which a SiO2 film is formed on a Si wafer) wafer.
- Non-Patent Document 2 it has been reported that the fixed charge amount varies depending on the film quality of the SiO 2 film, and that the fixed charge increases when the SiO 2 film becomes low in oxygen.
- film quality control of the SiO 2 film is effective for suppressing high-frequency distortion, but suppression of high-frequency distortion by film quality control and its control method have not been clarified so far.
- An object of the present invention is to reduce high-frequency distortion in a bonded body in which a piezoelectric material substrate is bonded to a support substrate made of silicon via a bonding layer made of a silicon oxide film.
- the present invention provides a support substrate made of silicon, 1.
- the inert setting the ratio of the gas flow rate to the oxygen gas flow rate (the inert gas flow rate/the oxygen gas flow rate) to 1.5 to 2.0; and bonding the bonding layer to the piezoelectric material substrate.
- the present invention relates to a method for manufacturing a joined body, characterized by having
- the inventor investigated the relationship between film quality and high-frequency distortion when forming a silicon oxide film with a reactive sputtering apparatus. Specifically, as a film quality evaluation method, the refractive index of the film was measured with an ellipsometer, and the value at a wavelength of 633 nm was calculated and used as an index. In addition, the refractive index of the silicon oxide film was changed by changing the flow rate ratio of the oxygen gas and the inert gas such as argon gas introduced into the sputtering apparatus during the formation of the silicon oxide film.
- FIG. (a) shows the state in which the bonding surface 4a of the piezoelectric material substrate 4 is activated by the plasma beam A
- FIG. (b) shows the state in which the bonding layer 2 is formed on the surface 1a of the supporting substrate 1
- (c) ) shows a state in which the bonding surface 2a of the bonding layer 2 on the supporting substrate 1 is activated by the plasma beam C.
- FIG. (a) shows a state in which the piezoelectric material substrate 4 and the support substrate 1 are bonded
- (b) shows a state in which the piezoelectric material substrate 4A is thinned by processing
- (c) shows the piezoelectric material substrate 4A.
- a state in which an electrode 6 is provided thereon is shown.
- 1 is a conceptual diagram of a reactive sputtering apparatus
- FIG. 4 is a graph showing the relationship between the argon gas/oxygen gas flow rate ratio and the target discharge voltage.
- FIG. 1 and 2 are schematic diagrams for explaining a manufacturing example in which a support substrate is directly bonded to a piezoelectric material substrate.
- the piezoelectric material substrate 4 has main surfaces 4a and 4b.
- the main surface 4a of the piezoelectric material substrate 4 is irradiated with a plasma beam as indicated by an arrow A to activate the main surface 4a to be an activated surface.
- a bonding layer 2 made of a silicon oxide film is provided on the bonding surface 1a of the support substrate 1.
- FIG. 1b is the main surface opposite to the joint surface 1a.
- the bonding surface 2a of the bonding layer 2 is irradiated with a plasma beam C to be activated to form an activated surface.
- the activated bonding surface 2a of the bonding layer 2 and the activated main surface 4a of the piezoelectric material substrate 4 are directly bonded to obtain the bonded body 5.
- the bonding surface 4b of the piezoelectric material substrate 4 of the bonded body 5 is further polished to reduce the thickness of the piezoelectric material substrate 4A as shown in FIG. 2(b), thereby obtaining a bonded body 5A.
- 4c is a polished surface.
- the elastic wave element 7 is produced by forming a predetermined electrode 6 on the polished surface 4c of the piezoelectric material substrate 4A.
- the support substrate is made of silicon.
- the relative density of the support substrate is preferably 95.5% or more, and may be 100%, from the viewpoint of bonding strength. Relative density is measured by the Archimedes method. Also, the method for manufacturing the supporting substrate is not particularly limited, but a sintering method is preferable.
- the silicon that constitutes the support substrate is preferably high resistance silicon.
- High-resistivity silicon means silicon with a volume resistivity of 1000 ⁇ cm or more.
- the upper limit of the volume resistivity of high resistance silicon is usually 10 k ⁇ cm due to manufacturing limitations.
- the material of the piezoelectric material substrate is not limited as long as it has the required piezoelectricity, but a single crystal having a composition of LiAO 3 is preferred.
- A is one or more elements selected from the group consisting of niobium and tantalum.
- LiAO 3 may be lithium niobate, lithium tantalate, or a lithium niobate-lithium tantalate solid solution.
- the thickness of the bonding layer is not particularly limited, it is preferably 0.01 to 10 ⁇ m, more preferably 0.01 to 0.5 ⁇ m, from the viewpoint of manufacturing cost.
- the refractive index of the bonding layer should be 1.468 or more and 1.474 or less. This makes it possible to reduce high frequency distortion.
- the refractive index of the bonding layer is measured with an ellipsometer under the following conditions. That is, a silicon oxide film of 400 nm to 500 nm is formed on a Si substrate, and the refractive index is measured with a spectroscopic ellipsometer. Set the incident angle and reflection angle to 70°, irradiate the substrate with incident light with a wavelength of 200 nm to 1000 nm, and calculate the refractive index from the polarization state of the reflected light.
- a method for forming the bonding layer is preferably a reactive sputtering method. That is, the inventor investigated the relationship between film quality and high-frequency distortion when forming a silicon oxide film with a reactive sputtering apparatus. At this time, as a method for evaluating the film quality of the silicon oxide film, the refractive index of the film was measured with an ellipsometer, and the value at a wavelength of 633 nm was calculated and used as an index. In addition, the inventors succeeded in intentionally changing the refractive index by changing the flow rate ratio of the inert gas and the oxygen gas introduced into the sputtering apparatus during the formation of the silicon oxide film.
- a procedure for forming a silicon oxide film using a reactive sputtering apparatus will be further described with reference to FIG.
- the target 14 and the support substrate 1 are opposed to each other in the inner space of the housing 11 of the apparatus.
- the power supply 13 has a positive pole connected to the housing 12 and a negative pole connected to the target 14 .
- a silicon target is used as the target 14 .
- an inert gas and an oxygen gas are supplied to the internal space of the housing 12 to generate plasma.
- inert gas atoms 17 flow toward target 14 .
- oxygen atoms 8 and silicon atoms 9 flow toward the surface of support substrate 1 .
- Excess gas is discharged from the discharge port 16 as indicated by an arrow D.
- silicon oxide which is a reaction product of oxygen and silicon, is produced on the support substrate 1 .
- the inventor of the present invention formed a bonding layer made of a silicon oxide film while changing the flow rate ratio (inert gas/oxygen gas) in the range of 0.9 to 3.5. High frequency distortion components could be suppressed in the range of 5 to 2.0. In addition, this made it possible to adjust the refractive index of the bonding layer to 1.468 to 1.474 (wavelength: 633 nm). It is considered that the refractive index of the bonding layer reflects the oxygen ratio contained in the silicon oxide film.
- FIG. 4 is a graph showing the results of plotting changes in the inert gas (argon)/oxygen flow rate ratio and changes in the discharge voltage when the discharge is controlled at a constant power.
- the flow rate ratio is 1.5 or more, the discharge voltage is stabilized.
- the flow rate ratio was less than 1.5, the discharge voltage abruptly decreased and hysteresis was observed.
- the internal space of the housing becomes oxygen-rich and the target surface is oxidized, thereby switching the film formation mode to the oxide mode. If the deposition mode changes to the oxide mode, the deposition rate will decrease and the target surface will be oxidized, forming an insulating layer and causing abnormal discharge (arcing), making it unsuitable as a bonding layer. .
- the deposition rate of the silicon oxide film forming the bonding layer is preferably in the range of 0.17 to 0.4 [nm/sec]. easy to get
- Specific manufacturing conditions for the bonding layer depend on the specifications of the chamber, and are appropriately selected. 10 ⁇ 2 Pa is preferred. Moreover, it is preferable that the film formation temperature is between room temperature and 250.degree. B can be exemplified as a dopant for the Si target.
- Argon can be exemplified as an inert gas supplied into the reactive sputtering apparatus.
- the current during reactive sputtering is preferably 5 to 10A, and the voltage is preferably 500 to 900V.
- the activated bonding surface of the bonding layer and the activated bonding surface of the piezoelectric material substrate are directly bonded.
- the arithmetic average roughness Ra of the activated bonding surface of the bonding layer is preferably 1 nm or less, more preferably 0.3 nm or less.
- the arithmetic mean roughness Ra of the activated bonding surface of the piezoelectric material substrate is preferably 1 nm or less, more preferably 0.3 nm or less. This further improves the bonding strength between the piezoelectric material substrate and the bonding layer.
- the use of the joined body of the present invention is not particularly limited, and for example, it can be suitably applied to acoustic wave devices and optical devices.
- a surface acoustic wave device has, on the surface of a piezoelectric material substrate, an input-side IDT (Interdigital Transducer) electrode (comb-shaped electrode or interdigital electrode) that excites a surface acoustic wave and an output-side electrode that receives the surface acoustic wave. and an IDT electrode.
- IDT Interdigital Transducer
- a high-frequency signal is applied to the IDT electrodes on the input side, an electric field is generated between the electrodes, and surface acoustic waves are excited and propagated on the piezoelectric material substrate. Then, the propagated surface acoustic wave can be taken out as an electric signal from the IDT electrode on the output side provided in the propagation direction.
- the bottom surface of the piezoelectric material substrate may have a metal film.
- the metal film plays a role of increasing the electromechanical coupling coefficient in the vicinity of the back surface of the piezoelectric material substrate when a Lamb wave element is manufactured as an acoustic wave device.
- the Lamb wave element has a structure in which comb-teeth electrodes are formed on the surface of the piezoelectric material substrate, and the metal film of the piezoelectric material substrate is exposed by a cavity provided in the supporting substrate. Examples of materials for such metal films include aluminum, aluminum alloys, copper, and gold.
- a composite substrate having a piezoelectric material layer without a metal film on the bottom surface may be used.
- the bottom surface of the piezoelectric material substrate may have a metal film and an insulating film.
- the metal film serves as an electrode when a thin film resonator is manufactured as an acoustic wave device.
- the thin film resonator has a structure in which electrodes are formed on the front and back surfaces of the piezoelectric material substrate, and the metal film of the piezoelectric material substrate is exposed by forming the insulating film as a cavity.
- Examples of materials for such metal films include molybdenum, ruthenium, tungsten, chromium, and aluminum.
- materials for the insulating film include silicon dioxide, phosphorus silica glass, boron phosphorus silica glass, and the like.
- examples of optical elements include an optical switching element, a wavelength conversion element, and an optical modulation element. Also, a periodically poled structure can be formed in the piezoelectric material substrate.
- the object of the present invention is an acoustic wave device
- the material of the piezoelectric material substrate is lithium tantalate, 36 to 47 from the Y axis to the Z axis centering on the X axis, which is the propagation direction of the surface acoustic wave. It is preferable to use the direction rotated by .degree. (for example, 42.degree.) because the propagation loss is small.
- the piezoelectric material substrate is made of lithium niobate
- the direction rotated from the Y-axis to the Z-axis by 60 to 68° (for example, 64°) around the X-axis, which is the propagation direction of the surface acoustic wave, is used. It is preferable to use it because the propagation loss is small.
- the size of the piezoelectric material substrate is not particularly limited, it is, for example, 50 to 150 mm in diameter and 0.2 to 60 ⁇ m in thickness.
- the bonding surface of the bonding layer and the bonding surface of the piezoelectric material substrate are irradiated with plasma to activate each flat surface.
- the atmosphere for surface activation is an atmosphere containing nitrogen or oxygen.
- the atmosphere may be oxygen only, nitrogen only, or a mixture of oxygen, nitrogen, hydrogen, and argon. In the case of a mixed gas, there is no particular limitation, but the ratio may be appropriately adjusted depending on the relationship with the bonding strength.
- the atmospheric pressure during surface activation is preferably 100 Pa or less, more preferably 80 Pa or less. Also, the atmospheric pressure is preferably 30 Pa or higher, more preferably 50 Pa or higher.
- the temperature during plasma irradiation is set to 150° C. or lower. As a result, it is possible to obtain the bonded body 7 having high bonding strength and free from deterioration of the piezoelectric material. From this point of view, the temperature during plasma irradiation is set to 150° C. or lower, and more preferably 100° C. or lower. Also, the energy during plasma irradiation is preferably 30 to 150W. Moreover, the product of the energy during plasma irradiation and the irradiation time is preferably 0.1 to 1.0 Wh.
- the bonding surface 4a of the piezoelectric material substrate and the bonding surface 2a of the bonding layer are flattened before the plasma treatment.
- Methods for flattening the bonding surfaces 2a, 4a include lap polishing, chemical mechanical polishing (CMP), and the like.
- the arithmetic mean roughness Ra of the flat surface is preferably 1 nm or less, more preferably 0.3 nm or less.
- the activated bonding surface of the piezoelectric material substrate and the activated bonding surface of the bonding layer are brought into contact and bonded.
- the joined body is heat-treated, so that the piezoelectric material substrate can be given strength to withstand the polishing process.
- Such heat treatment temperature is preferably 100 to 150.degree.
- the thickness can be reduced by processing the piezoelectric material substrate after this heat treatment.
- the activated surfaces are brought into contact with each other and joined.
- the temperature at this time is normal temperature, specifically, it is preferably 40° C. or less, more preferably 30° C. or less.
- the temperature at the time of joining is particularly preferably 20° C. or higher and 25° C. or lower.
- the pressure during bonding is preferably 100 to 20000N.
- bonded bodies of each example shown in Table 1 were produced.
- a lithium tantalate substrate (LT substrate) having an OF portion, a diameter of 4 inches, and a thickness of 250 ⁇ m was used as the piezoelectric material substrate 4 .
- LT substrate a 46° Y-cut X-propagation LT substrate was used in which the surface acoustic wave (SAW) propagation direction was X and the cut-out angle was a rotated Y-cut plate.
- the bonding surface 4a of the piezoelectric material substrate 4 was mirror-polished so that the arithmetic mean roughness Ra was 0.3 nm. However, Ra is measured in a field of view of 10 ⁇ m ⁇ 10 ⁇ m with an atomic force microscope (AFM).
- AFM atomic force microscope
- a support substrate 1 made of high resistance ( ⁇ 2 k ⁇ cm) silicon having an orientation flat (OF) portion, a diameter of 4 inches and a thickness of 230 ⁇ m was prepared.
- Surfaces 1a and 1b of support substrate 1 are finished by chemical mechanical polishing (CMP), and each has an arithmetic mean roughness Ra of 0.2 nm.
- a bonding layer 2 made of SiO 2 was formed to a thickness of 1 ⁇ m on the surface of the support substrate, and the bonding surface 2a was polished by CMP to a thickness of about 0.1 ⁇ m to be planarized.
- ultrasonic cleaning was performed using pure water, and the bonding surfaces of the piezoelectric material substrate and the bonding layer were dried by spin drying.
- the supporting substrate after cleaning was introduced into a plasma activation chamber, and the bonding surface was activated at 30° C. with nitrogen gas plasma.
- the piezoelectric material substrate was introduced into the plasma activation chamber, and the bonding surface of the bonding layer was surface-activated with nitrogen gas plasma at 30°C.
- the surface activation time was 40 seconds and the energy was 100W. For the purpose of removing particles attached during surface activation, the same ultrasonic cleaning and spin drying as above were performed again.
- the bonding surface of the piezoelectric material substrate and the bonding surface of the bonding layer were aligned, and the bonding surfaces activated at room temperature were brought into contact with each other.
- the bonding wave As a result of applying pressure to the center of the superimposed substrates, it was observed that the adhesion between the substrates spread (so-called bonding wave), and it was confirmed that the pre-bonding was performed satisfactorily.
- the joined body was placed in an oven in a nitrogen atmosphere and heated at 130° C. for 4 hours. The surface of the piezoelectric material substrate of the joined body was removed from the oven and thinned to 1 ⁇ m by grinding and polishing.
- the bonding layer 2 was formed by a reactive sputtering method according to the procedure described with reference to FIG. However, the total pressure in the internal space of the housing was set to 0.1-0.2Pa, the current was set to 5-10A, and the voltage was set to 500-900V. Also, the flow rate ratio of argon gas and oxygen gas was changed within the range of 0.90 to 3.50.
- the refractive index at 633 nm of the bonding layer of each example was measured by an ellipsometer, and the results are shown in Table 1. Further, Table 1 shows the magnitude of the second harmonic of the obtained device (normalized with the magnitude of the second harmonic of Comparative Example 1 as 0.0%).
- the target discharge voltage changed as shown in FIG. 4 within the flow rate ratio range of 0.9 to 1.5. That is, it was found that the film formation mode in reactive sputtering switches from the metal mode to the oxide mode when the flow ratio is less than 1.5.
- the refractive index of the bonding layer is 1.468 or more and 1.474 or less. (especially preferably 1.472 or more).
- the deposition rate of the silicon oxide film was 0.17 to 0.4 (nm/sec). Within this range, we succeeded in greatly reducing the magnitude of the second harmonic.
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Abstract
Description
圧電性材料基板、および
前記支持基板の表面上に設けられた接合層であって、珪素酸化物膜からなる接合層
を有しており、前記接合層の屈折率が1.468以上、1.474以下であることを特徴とする、接合体に係るものである。
前記接合層を圧電性材料基板と接合する工程
を有することを特徴とする、接合体の製造方法に係るものである。
また、不活性ガス/酸素ガス流量比を1.5~2.0の範囲に制御することで、高周波歪み成分を抑制することができた。
こうした作用効果のメカニズムは明確ではないが、接合層を構成する酸化珪素膜中の酸素量が変化し、固定電荷量が減少したものと考えられる。
図1、図2は、支持基板を圧電性材料基板に直接接合する製造例を説明するための模式図である。
次いで、接合体5の圧電性材料基板4の接合面4bを更に研磨加工し、図2(b)に示すように圧電性材料基板4Aの厚さを小さくし、接合体5Aを得る。4cは研磨面である。
すなわち、Si基板上に珪素酸化物を400nm~500nm成膜し、分光型エリプソメーターで屈折率を測定する。入射角および反射角を70°に設定し、波長200nm~1000nmまでの入射光を基板へ照射し、反射光の偏光状態から屈折率を算出する。
すなわち、本発明者は、反応性スパッタリング装置で珪素酸化物膜を形成する場合において、膜質と高周波歪みの関係を調査した。この際、珪素酸化物膜の膜質の評価手法として、膜の屈折率をエリプソメーターで測定して、波長633nmにおける値を算出し、指標としてみた。
また、珪素酸化物膜の形成時に、スパッタリング装置へ導入する不活性ガスと酸素ガスの流量比を変化させることで意図的に屈折率を変化させることに成功した。
装置の筐体11の内部空間でターゲット14と支持基板1とを対向させる。電源13の正極は筐体12に接続されており、負極はターゲット14に接続されている。ターゲット14としてはシリコンターゲットを用いる。そして、筐体12の内部空間に不活性ガスと酸素ガスとを供給し、プラズマを生成させる。この結果、不活性ガスの原子17はターゲット14に向かって流れる。一方、酸素原子8およびシリコン原子9は支持基板1の表面に向かって流れる。余剰のガスは排出口16から矢印Dのように排出される。この過程で、支持基板1上で酸素とシリコンの反応物である珪素酸化物が生ずる。
すなわち、図4は、定電力で放電を制御した場合における、不活性ガス(アルゴン)/酸素流量比率の変化と放電電圧の変化をプロットした結果を示すグラフである。前記流量比率が1.5以上になると前記放電電圧が安定する。しかし、前記流量比率が1.5未満になると、放電電圧が急激に低下し、かつヒステリシスが観測された。これは、筐体の内部空間が酸素リッチな状態となり、ターゲット表面が酸化することで、成膜モードが酸化物モードに切り替わったことによるものである。成膜モードが酸化物モードになると、成膜レートの低下や、ターゲット表面が酸化することで絶縁層が形成されて、異常放電(アーキング)が発生するので、接合層としては不適なものとなる。
また、Siターゲットのドーパントとしては、Bを例示できる。
また、反応性スパッタリング時の電流は5~10Aが好ましく、電圧は500~900Vが好ましい。
本発明の接合体の用途は特に限定されず、例えば、弾性波素子や光学素子に好適に適用できる。
まず接合層の接合面および圧電性材料基板の接合面にプラズマを照射することで、各平坦面を活性化する。
表面活性化時の雰囲気は、窒素や酸素を含有する雰囲気とする。この雰囲気は、酸素のみであってよく、窒素のみであってよく、あるいは酸素と、窒素、水素、およびアルゴンとの混合ガスであってよい。混合ガスの場合には、特に限定されるものではないが、接合強度との関係によりその比率を適宜調整してもよい。
プラズマ照射時の温度は150℃以下とする。これによって、接合強度が高く、かつ圧電性材料の劣化のない接合体7が得られる。この観点から、プラズマ照射時の温度を150℃以下とするが、100℃以下とすることが更に好ましい。
また、プラズマ照射時のエネルギーは、30~150Wが好ましい。また、プラズマ照射時のエネルギーと照射時間との積は、0.1~1.0Whが好ましい。
具体的には、OF部を有し、直径が4インチ,厚さが250μmのタンタル酸リチウム基板(LT基板)を、圧電性材料基板4として使用した。LT基板は、弾性表面波(SAW)の伝搬方向をXとし、切り出し角が回転Yカット板である46°YカットX伝搬LT基板を用いた。圧電性材料基板4の接合面4aは、算術平均粗さRaが0.3nmとなるように鏡面研磨しておいた。ただし、Raは、原子間力顕微鏡(AFM)によって10μm×10μmの視野で測定する。
次いで、純水を用いた超音波洗浄を実施し、スピンドライにより圧電性材料基板および接合層の接合面を乾燥させた。次いで、洗浄後の支持基板をプラズマ活性化チャンバーに導入し、窒素ガスプラズマで30℃で接合面を活性化した。また、圧電性材料基板を同様にプラズマ活性化チャンバーに導入し、窒素ガスプラズマで30℃で接合層の接合面を表面活性化した。表面活性化時間は40秒とし、エネルギーは100Wとした。表面活性化中に付着したパーティクルを除去する目的で、上述と同じ超音波洗浄、スピンドライを再度実施した。
オーブンから取り出した接合体の圧電性材料基板の表面を研削加工、研磨加工により1μmまで薄化した。
各例の接合層について、エリプソメーターによって633nmでの屈折率を測定し、結果を表1に示す。更に、得られた素子の2次高調波の大きさを表1に示す(比較例1の2次高調波の大きさを0.0%として規格化した)。
Claims (6)
- シリコンからなる支持基板、
圧電性材料基板、および
前記支持基板の表面上に設けられた接合層であって、珪素酸化物膜からなる接合層
を有しており、前記接合層の屈折率が1.468以上、1.474以下であることを特徴とする、接合体。 - 前記圧電性材料基板が、ニオブ酸リチウム、タンタル酸リチウムおよびニオブ酸リチウム-タンタル酸リチウムからなる群より選ばれた材質からなることを特徴とする、請求項1記載の接合体。
- 反応性イオンスパッタリング法によって、少なくとも不活性ガスおよび酸素ガスを流しながら、シリコンからなる支持基板の表面上に珪素酸化物膜からなる接合層を成長させるのに際して、前記不活性ガスの流量の前記酸素ガスの流量に対する比率(前記不活性ガスの流量/前記酸素ガスの流量)を1.5~2.0とする工程、および
前記接合層を圧電性材料基板と接合する工程
を有することを特徴とする、接合体の製造方法。 - 前記珪素酸化物膜の成膜速度を0.17~0.4(nm/sec)とすることを特徴とする、請求項3記載の方法。
- 前記接合層の屈折率が1.468以上、1.474以下であることを特徴とする、請求項3または4記載の方法。
- 前記圧電性材料基板が、ニオブ酸リチウム、タンタル酸リチウムおよびニオブ酸リチウム-タンタル酸リチウムからなる群より選ばれた材質からなることを特徴とする、請求項3~5のいずれか一つの請求項に記載の方法。
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7213314B2 (en) | 2002-07-03 | 2007-05-08 | Triquint, Inc. | Method of forming a surface acoustic wave (SAW) filter device |
JP2010040877A (ja) * | 2008-08-06 | 2010-02-18 | Seiko Epson Corp | 接合方法、接合体、液滴吐出ヘッドおよび液滴吐出装置 |
JP2016225537A (ja) | 2015-06-02 | 2016-12-28 | 信越化学工業株式会社 | 酸化物単結晶薄膜を備えた複合ウェーハの製造方法 |
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JPH04258008A (ja) * | 1991-02-12 | 1992-09-14 | Murata Mfg Co Ltd | 弾性表面波装置の製造方法 |
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Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7213314B2 (en) | 2002-07-03 | 2007-05-08 | Triquint, Inc. | Method of forming a surface acoustic wave (SAW) filter device |
JP2010040877A (ja) * | 2008-08-06 | 2010-02-18 | Seiko Epson Corp | 接合方法、接合体、液滴吐出ヘッドおよび液滴吐出装置 |
JP2016225537A (ja) | 2015-06-02 | 2016-12-28 | 信越化学工業株式会社 | 酸化物単結晶薄膜を備えた複合ウェーハの製造方法 |
Non-Patent Citations (3)
Title |
---|
"Control of fixed charge at Si-Si02 interface by oxidation-reduction treatments", APPL. PHYS. LETT., vol. 22, no. 8, 15 April 1973 (1973-04-15) |
"Impact of Si substrate resistivity on the non — linear behaviour of RF CPW transmission lines", PROCEEDINGS OF THE 3RD EUROPEAN MICROWAVE INTEGRATED CIRCUITS CONFERENCE, January 2008 (2008-01-01) |
See also references of EP4131777A4 |
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