WO2011111732A1 - Manufacturing method for sensor element equipped with pzt film - Google Patents

Manufacturing method for sensor element equipped with pzt film Download PDF

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Publication number
WO2011111732A1
WO2011111732A1 PCT/JP2011/055470 JP2011055470W WO2011111732A1 WO 2011111732 A1 WO2011111732 A1 WO 2011111732A1 JP 2011055470 W JP2011055470 W JP 2011055470W WO 2011111732 A1 WO2011111732 A1 WO 2011111732A1
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Prior art keywords
pzt film
soi substrate
upper electrode
lower electrode
sensor element
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PCT/JP2011/055470
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French (fr)
Japanese (ja)
Inventor
徹治 今村
雅英 田村
中野　貴之
秀和 矢野
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北陸電気工業株式会社
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Priority to CN201180013522.XA priority Critical patent/CN102792477B/en
Priority to KR1020127026453A priority patent/KR101782447B1/en
Priority to JP2012504490A priority patent/JP5100915B2/en
Publication of WO2011111732A1 publication Critical patent/WO2011111732A1/en

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    • 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
    • H10N30/05—Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
    • 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
    • H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
    • 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
    • H10N30/074—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
    • H10N30/076—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing by vapour phase deposition
    • 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
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H10N30/302—Sensors
    • 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
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/853—Ceramic compositions
    • H10N30/8548—Lead-based oxides
    • H10N30/8554—Lead-zirconium titanate [PZT] based

Definitions

  • the present invention relates to a method for manufacturing a sensor element having a PZT film that can be used for an angular velocity sensor (gyro), an acceleration sensor, or the like.
  • Patent Document 1 discloses a piezoelectric angular velocity sensor (piezoelectric gyro) including a sensor element having a PZT (lead zirconate titanate) film.
  • This publication does not specifically describe the method of forming the PZT film, but usually a lower electrode is formed on one surface of an SOI substrate having a predetermined thickness in advance, and the other surface side of the SOI substrate is used. A PZT film is formed on the lower electrode while the SOI substrate is heated. Then, the PZT film is etched to form a predetermined PZT film pattern. Next, an upper electrode having a predetermined pattern facing the lower electrode is formed on the PZT film pattern. Next, an etching process is performed on the SOI substrate to form a flexible portion having flexibility.
  • An object of the present invention is to provide a method of manufacturing a sensor element having a PZT film that can form a PZT film of good quality and almost homogeneous.
  • Another object of the present invention is to provide a sensor element having a PZT film that can prevent the PZT film from being charged even if the SOI substrate is held by an electrostatic chuck from the upper electrode side when the SOI substrate is etched. It is to provide a manufacturing method.
  • a sensor element including a PZT film is manufactured as follows. First, a lower electrode is formed on one surface of an SOI substrate having a thickness of 550 ⁇ m or more.
  • an SOI substrate required for a sensor element provided with a PZT film is considered to be around 400 ⁇ m. For this reason, conventionally, a PZT film is formed using an SOI substrate having a thickness of about 400 ⁇ m from the beginning.
  • an SOI substrate having a thickness of 550 ⁇ m or more, which is larger than necessary is used. Then, a PZT film is formed on the lower electrode while the SOI substrate is heated from the other surface side of the SOI substrate.
  • the “PZT film” is a film of lead zirconate titanate, and is a film made of a mixed crystal of lead titanate and lead zirconate.
  • the “SOI substrate” is a substrate having a structure in which a SiO 2 layer is inserted in a Si layer.
  • the PZT film is then etched to form a predetermined PZT film pattern, and an upper electrode having a predetermined pattern facing the lower electrode is formed on the PZT film pattern.
  • the other surface of the SOI substrate is polished to mirror the other surface, and the thickness of the SOI substrate is reduced to a predetermined thickness (for example, about 400 ⁇ m) that effectively exhibits the characteristics of the PZT film pattern.
  • etching is performed from the other surface of the SOI substrate to form a flexible portion having flexibility.
  • the inventors have found that, when a PZT film is formed using an SOI substrate having a thickness of 550 ⁇ m or more as in the present invention, a high-quality and almost homogeneous PZT crystal can be obtained. The reason for this is not clear, but the inventor believes that there is distortion in the SOI substrate due to heat during heating when forming the PZT film.
  • the other surface of the SOI substrate is polished to obtain a desired thickness. Therefore, even if a thick SOI substrate is used initially, the SOI substrate having the desired thickness is used.
  • a sensor element provided with a substrate can be formed.
  • the formation of the PZT film by the etching process is preferably performed in a state where the other surface of the SOI substrate is not polished (rough state). In this case, since the heat applied from the other surface of the SOI substrate enters the SOI substrate evenly, the uniform generation of the PZT film is further improved.
  • the temperature for heating the SOI substrate is preferably 500 to 800 ° C. If the heating temperature is below 500 ° C., the PZT film cannot be formed sufficiently. On the other hand, when the heating temperature exceeds 800 ° C., a desired composition ratio cannot be obtained due to evaporation of Pb.
  • the thickness dimension of the SOI substrate is desirably 550 to 750 ⁇ m, but the upper limit is naturally determined in consideration of the influence of the heating temperature, and it is not necessary to make the thickness more than necessary.
  • the electrostatic chuck is preferably an electrostatic chuck that can cool and fix the substrate uniformly.
  • an electrostatic chuck is simply used, the PZT film is charged and film breakage occurs, and the adhesion strength with each layer decreases. As a result, desired piezoelectric characteristics cannot be obtained. Therefore, it is desirable to hold the SOI substrate by the electrostatic chuck from the upper electrode side with the upper electrode and the lower electrode at the same potential.
  • a known electrostatic chuck may be used. When the upper electrode and the lower electrode are set to the same potential, the PZT film is difficult to be charged, so that the characteristics of the PZT film are hardly affected.
  • the SOI substrate is held by performing electrostatic chucking on the SOI substrate from the upper electrode side, a portion of the PZT film pattern on which the upper electrode pattern is formed and a portion on which the upper electrode pattern is not formed by the voltage received from the electrostatic chuck A different electric field is generated.
  • the PZT film pattern is distorted, and the PZT film pattern may be ruptured or the adhesion strength with each layer may be reduced. Therefore, after the PZT film pattern is formed, the upper electrode may not be formed immediately, but the upper electrode may be formed after polishing and etching for forming the flexible portion. In this case, first, an upper electrode material layer for forming an upper electrode is formed on the PZT film pattern.
  • the thickness of the SOI substrate is reduced to a predetermined thickness by polishing as described above, and the flexible portion is formed by etching.
  • the upper electrode material layer formed on the PZT film pattern is etched to form an upper electrode having a predetermined pattern on the PZT film pattern.
  • the SOI substrate is held from the upper electrode material layer side by the electrostatic chuck while the upper electrode material layer and the lower electrode are at the same potential. do it.
  • the upper electrode can be formed to include a lower electrode output electrode that extracts the output of the lower electrode.
  • a through-conductive portion that is formed together with the upper electrode in a through-hole penetrating the PZT film pattern in the thickness direction and connects the lower electrode output electrode and the lower electrode, and together with the upper electrode on the PZT film pattern It is possible to form a state in which the same potential is formed by the surface conductive portion that is formed and connects the lower electrode output electrode and the other upper electrode.
  • a lower electrode and the whole upper electrode can be electrically connected by the penetration conductive part and a surface conductive part, and it can be made the same electric potential. Since the through conductive portion and the surface conductive portion are formed together with the upper electrode, the upper electrode and the lower electrode can be easily set to the same potential.
  • the SOI substrate is etched, it is preferable that a plurality of sensor elements are formed using the multi-cavity substrate, and the surface conductive portion is made non-conductive when the multi-cavity substrate is divided. In this way, the sensor elements can be mass-produced using the multi-piece substrate, and the same potential state can be released at the same time as the multi-piece substrate is divided.
  • FIG. 2 is a sectional view taken along line II-II in FIG. (A)-(F) are process drawings which show an example of the manufacturing method of embodiment of this invention. It is a figure for demonstrating the manufacturing method of embodiment of this invention.
  • FIG. 4 is an X-ray diffraction pattern of components of a PZT film of the sensor element of the example manufactured by the method shown in FIGS. 3 (A) to (F). It is a X-ray diffraction pattern of the component of the PZT film
  • FIGS. 4A to 4F are process diagrams showing another example of the manufacturing method according to the embodiment of the present invention.
  • FIG. 1 is a plan view of a sensor element (piezoelectric angular velocity sensor) 1 having a PZT film manufactured by the method of the embodiment of the present invention
  • FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
  • the angular velocity sensor 1 of this example includes a sensor main body 3 and a detection unit 5.
  • the sensor body 3 has a cylindrical weight 7 positioned at the center, a cylindrical support 9 positioned on the outer periphery, and a flexible portion having flexibility between the weight 7 and the support 9. 11 is formed by etching the SOI substrate.
  • the thickness L1 of the sensor body 3 is about 405 ⁇ m.
  • the detection unit 5 and the flexible unit 11 are drawn with exaggerated thickness dimensions.
  • reference numeral 10 denotes an Si layer
  • 17 denotes an Si active layer
  • 13 denotes an insulating layer made of an oxide film
  • 15 denotes an SiO 2 layer.
  • the weight 7 and the support portion 9 are configured by processing the Si layer 10.
  • the flexible portion 11 includes an insulating layer 13, an active layer 17, and a SiO 2 layer 15.
  • the detection unit 5 is formed on the lower electrode E0 formed on the insulating layer 13, the PZT film pattern 19 formed on the lower electrode E0, and the PZT film pattern 19, and faces the lower electrode E0.
  • the upper electrode E1 is formed.
  • the PZT film pattern 19 is made of PZT formed by sputtering using Pb 1.3 (Zr 0.52 Ti 0.48 ) O X as a target, and has a thickness dimension of 3 ⁇ m.
  • the upper electrode E1 is composed of a laminated thin film of Ti and Au.
  • the lower electrode E0 is mainly formed on the flexible portion 11, and is composed of a laminated thin film of Ti and Pt.
  • the upper electrode E1 includes a plurality of detection electrodes E11 that detect an angular velocity by a change in surface charge, a plurality of drive electrodes E12 that are used to vibrate the weight 7, and a lower electrode output electrode E13.
  • the lower electrode output electrode E13 is electrically connected to the lower electrode E0 by a through conductive portion 21 formed in a through hole 19a penetrating the PZT film pattern 19 in the thickness direction, and takes out the output of the lower electrode E0. Plays.
  • FIG. 3A shows a cross section of one sensor element included in a multi-piece substrate for convenience.
  • the SOI substrate 31 has a structure in which a SiO 2 layer 15 ′ is inserted between the Si layer 10 ′ and the Si active layer 17 ′.
  • the Si active layer 17 ' is activated.
  • An insulating layer 33 made of an oxide film is formed on the lower surface of the Si substrate 10 ', and an insulating layer 13' made of an oxide film is also formed on the Si active layer 17 '.
  • the thickness dimension L2 of the SOI substrate 31 used in this example is about 625 ⁇ m (see FIG. 3A).
  • the thickness dimension L2 of the SOI substrate 31 is preferably 550 to 750 ⁇ m.
  • a lower electrode E0 is formed on one surface (insulating layer 13 ′) of the SOI substrate 31.
  • the lower electrode E0 is formed by forming a 20 nm thick Ti film on one surface of the SOI substrate 31 by sputtering, oxidizing the Ti film, and forming a 100 nm thick Pt film thereon by sputtering.
  • the SOI substrate 31 is placed on the heater H, and the lower electrode is heated in a state where the SOI substrate 31 is heated at about 700 ° C. from the other surface side of the SOI substrate 31.
  • a PZT film 37 is formed on E0. Specifically, a PZT film 37 having a thickness of 3 ⁇ m is formed by sputtering using Pb 1.3 (Zr 0.52 Ti 0.48 ) O X as a target.
  • the heating temperature is preferably 500 to 800 ° C.
  • the step of forming the PZT film 37 is performed in a state where the other surface of the SOI substrate 31 is not polished (rough state).
  • a wet etching process is performed to form a PZT film pattern 19 having a predetermined shape including a through hole 19a as shown in FIG. To do.
  • the upper electrode material layer 39 and the through conductive portion 21 are formed.
  • the through conductive portion 21 is formed together with the upper electrode material layer 39 in the through hole 19a so as to connect to the lower electrode E0.
  • the upper electrode material layer 39 and the penetrating conductive portion 21 are formed by sputtering a Ti film having a thickness of 20 nm on one surface including the PZT film pattern 19 over the entire surface, and then oxidizing the Ti film.
  • a 300 nm Au film is formed by sputtering.
  • FIG. 4 is a plan view of the multi-piece substrate after the upper electrode E1 is formed.
  • the lower electrode output electrode E13 and other upper electrodes are electrically connected by the surface conductive portion 41 formed on the PZT film pattern 19. Yes. For this reason, after formation of the upper electrode E1, the lower electrode E0 and the upper electrode E1 are electrically connected.
  • the other surface of the SOI substrate 31 is polished to reduce the thickness of the SOI substrate 31 to a predetermined thickness (L1 dimension in FIG. 2: 405 ⁇ m) that effectively exhibits the characteristics of the PZT film.
  • the other surface (back surface) of the polished SOI substrate 31 is in a mirror state.
  • an etching process is performed from the other surface of the SOI substrate 31 to form the weight 7, the support portion 9, and the flexible portion 11 as shown in FIG.
  • the SOI substrate 31 is held by the electrostatic chuck C from the upper electrode E1 side.
  • an etching process is performed from the other surface (back surface) of the SOI substrate 31 by dry etching using a photolithography technique.
  • the SOI substrate 31 is viewed from the upper electrode E1 side while the upper electrode E1 and the lower electrode E0 are at the same potential. It is held by the electrostatic chuck C. Therefore, even if the electrostatic chuck C is used, the PZT film is hardly charged.
  • the multi-piece substrate is divided. Since the surface is divided along the broken line B shown in FIG. 4 at the time of division, the surface conductive portion 41 becomes non-conductive. As a result, the electrical connection between the detection electrode E11 and the drive electrode E12 and the lower electrode E0 is released.
  • FIG. 5 is an X-ray diffraction (XRD) diagram of the central portion of the PZT film of the sensor element (Example) manufactured by the above method
  • FIG. 6 is an SOI substrate (thickness dimension: 400 ⁇ m) that is thin when the PZT film is formed. It is an X-ray diffraction pattern of the component of the center part of the PZT film
  • PZT (100) is PZT having a crystal orientation of (100). Pyro is an unnecessary peak that occurs in a low temperature range.
  • Table 1 shows the intensity ratios of PZT (100) / Pyro and PZT (100) / PZT (111) determined from both figures.
  • (X00) indicates the center of the PZT film
  • (X40) indicates a position 40 mm in the X direction from the center of the PZT film.
  • the PZT film of the sensor element preferably has a high PZT (100) / Pyro and PZT (100) / PZT (111). From Table 1, it can be seen that in both (X00) and (X40), PZT (100) / Pyro and PZT (100) / PZT (111) of the PZT film of the example are larger than those of the comparative example. .
  • FIG. 7 parts common to FIG. 3 are given the same reference numerals as those shown in FIG.
  • FIGS. 7A to 7E the same steps as those in the example of the present invention shown in FIG. 3 are carried out from FIGS. 7A to 7E (see FIGS. 3A to 3E).
  • the SOI substrate 131 is held by the electrostatic chuck C ′ from the upper electrode material layer 139 side.
  • FIG. 7F an etching process is performed from the other surface (back surface) of the SOI substrate 131 as described above.
  • the SOI substrate 131 is formed with the upper electrode material layer 139 and the lower electrode E100 at the same potential. It is held by the electrostatic chuck C ′ from the material layer 139 side.
  • the electrostatic chuck C ′ is performed in the state of the upper electrode material layer 139 before forming the upper electrode pattern, the upper electrode pattern is formed as in the example of FIG. Different electric fields are not generated between the portions that are not formed and the portions that are not formed. Therefore, if the manufacturing process shown in FIG. 7 is adopted, it is difficult for the PZT film pattern 119 to be distorted, and it is possible to reliably prevent the PZT film pattern 119 from rupturing or lowering the adhesion strength with each layer.
  • the SOI substrate is thinned to a desired thickness, so that a high-quality and uniform PZT film can be obtained.

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Abstract

Disclosed is a manufacturing method for a sensor element equipped with a PZT film, that forms a good quality, and substantially homogenous PZT film. The method forms a lower electrode E0 on a surface of one side of an SOI substrate 31 having a thickness of 550 µm or more. A PZT film 37 is formed on the lower electrode E0 when the SOI substrate 31 is heated from a surface side of another side of the SOI substrate 31. A predetermined PZT film pattern 19 is formed by implementing an etching process on the PZT film 37. An upper electrode E1 is formed with a predetermined pattern that opposes the lower electrode E0 on the PZT film pattern 19. A polishing process is implemented on a surface of another side of the SOI substrate 31 thereby thinning the thickness of the SOI substrate 31 to a predetermined thickness to effectively develops a characteristic of the PZT film pattern 19. Thereafter, a flexible portion 11 is formed having flexibility by implementing an etching process on a surface of another side of the SOI substrate 31.

Description

ＰＺＴ膜を備えたセンサ素子の製造方法Manufacturing method of sensor element provided with PZT film
　本発明は、角速度センサ（ジャイロ）や加速度センサ等に用いることができるＰＺＴ膜を備えたセンサ素子の製造方法に関するものである。 The present invention relates to a method for manufacturing a sensor element having a PZT film that can be used for an angular velocity sensor (gyro), an acceleration sensor, or the like.
　特開２００８－１９０９３１号公報（特許文献１）には、ＰＺＴ（チタン酸ジルコン酸鉛）膜を備えたセンサ素子を備えた圧電型角速度センサ（圧電型ジャイロ）が示されている。この公報には、ＰＺＴ膜の形成方法については具体的に記載されていないが、通常予め所定の厚みのＳＯＩ基板の一方の面上に下部電極を形成し、該ＳＯＩ基板の他方の面側からＳＯＩ基板を加熱した状態で、下部電極の上にＰＺＴ膜を形成する。そして、ＰＺＴ膜にエッチング処理を施して所定のＰＺＴ膜パターンを形成する。次に、ＰＺＴ膜パターンの上に下部電極と対向する所定のパターンの上部電極を形成する。次に、ＳＯＩ基板にエッチング処理を施して可撓性を有する可撓部を形成する。 Japanese Unexamined Patent Application Publication No. 2008-190931 (Patent Document 1) discloses a piezoelectric angular velocity sensor (piezoelectric gyro) including a sensor element having a PZT (lead zirconate titanate) film. This publication does not specifically describe the method of forming the PZT film, but usually a lower electrode is formed on one surface of an SOI substrate having a predetermined thickness in advance, and the other surface side of the SOI substrate is used. A PZT film is formed on the lower electrode while the SOI substrate is heated. Then, the PZT film is etched to form a predetermined PZT film pattern. Next, an upper electrode having a predetermined pattern facing the lower electrode is formed on the PZT film pattern. Next, an etching process is performed on the SOI substrate to form a flexible portion having flexibility.
特開２００８－１９０９３１号公報JP 2008-190931 A
　しかしながら、実際にＰＺＴ膜を形成すると、良質でほぼ均質なＰＺＴ膜を簡単に形成することが難しいという問題に直面した。Ｘ線回折（ＸＲＤ）解析を行なうと、問題のあるＰＺＴ膜では、Ｐｙｒｏや（１１１）面のような不要なピークに対する（１００）面への優先配向の割合である［ＰＺＴ（１００）／Ｐｙｒｏ］、及び［ＰＺＴ（１００）／ＰＺＴ（１１１）］の値が小さくなっている。 However, when a PZT film was actually formed, it was difficult to easily form a high-quality, almost homogeneous PZT film. When X-ray diffraction (XRD) analysis is performed, in a problematic PZT film, the ratio of the preferential orientation to the (100) plane with respect to an unnecessary peak such as Pyro or (111) plane is [PZT (100) / Pyro. ] And [PZT (100) / PZT (111)] are small.
　本発明の目的は、良質でほぼ均質なＰＺＴ膜を形成できるＰＺＴ膜を備えたセンサ素子の製造方法を提供することにある。 An object of the present invention is to provide a method of manufacturing a sensor element having a PZT film that can form a PZT film of good quality and almost homogeneous.
　本発明の他の目的は、ＳＯＩ基板をエッチング処理する際に、ＳＯＩ基板を上部電極側から静電チャックにより保持しても、ＰＺＴ膜が帯電するのを防止できるＰＺＴ膜を備えたセンサ素子の製造方法を提供することにある。 Another object of the present invention is to provide a sensor element having a PZT film that can prevent the PZT film from being charged even if the SOI substrate is held by an electrostatic chuck from the upper electrode side when the SOI substrate is etched. It is to provide a manufacturing method.
　本発明では、以下のようにＰＺＴ膜を備えたセンサ素子を製造する。まず、５５０μｍ以上の厚みを有するＳＯＩ基板の一方の面上に下部電極を形成する。一般的にＰＺＴ膜を備えたセンサ素子に必要とされるＳＯＩ基板は、４００μｍ前後と考えられている。そのため従来は、最初から４００μｍ前後の厚みのＳＯＩ基板を用いてＰＺＴ膜を形成しているが、本発明では必要な厚みより厚い、５５０μｍ以上の厚みを有するＳＯＩ基板を用いる。そしてＳＯＩ基板の他方の面側からＳＯＩ基板を加熱した状態で、下部電極の上にＰＺＴ膜を形成する。本願明細書において、「ＰＺＴ膜」とは、チタン酸ジルコン酸鉛の膜であり、チタン酸鉛とジルコン酸鉛の混晶からなる膜である。また、「ＳＯＩ基板」とは、Ｓｉ層内にＳｉＯ２層が挿入された構造を有する基板である。 In the present invention, a sensor element including a PZT film is manufactured as follows. First, a lower electrode is formed on one surface of an SOI substrate having a thickness of 550 μm or more. In general, an SOI substrate required for a sensor element provided with a PZT film is considered to be around 400 μm. For this reason, conventionally, a PZT film is formed using an SOI substrate having a thickness of about 400 μm from the beginning. However, in the present invention, an SOI substrate having a thickness of 550 μm or more, which is larger than necessary, is used. Then, a PZT film is formed on the lower electrode while the SOI substrate is heated from the other surface side of the SOI substrate. In the present specification, the “PZT film” is a film of lead zirconate titanate, and is a film made of a mixed crystal of lead titanate and lead zirconate. The “SOI substrate” is a substrate having a structure in which a SiO 2 layer is inserted in a Si layer.
　本発明では、次に、ＰＺＴ膜にエッチング処理を施して所定のＰＺＴ膜パターンを形成し、ＰＺＴ膜パターンの上に下部電極と対向する所定のパターンの上部電極を形成する。次に、ＳＯＩ基板の他方の面に研磨加工を施して、他方の面をミラー化すると共に、ＳＯＩ基板の厚みをＰＺＴ膜パターンの特性を有効に発揮させる所定の厚み（例えば４００μｍ前後）まで薄くする。その後、ＳＯＩ基板の他方の面からエッチング処理を施して可撓性を有する可撓部を形成する。 In the present invention, the PZT film is then etched to form a predetermined PZT film pattern, and an upper electrode having a predetermined pattern facing the lower electrode is formed on the PZT film pattern. Next, the other surface of the SOI substrate is polished to mirror the other surface, and the thickness of the SOI substrate is reduced to a predetermined thickness (for example, about 400 μm) that effectively exhibits the characteristics of the PZT film pattern. To do. Thereafter, etching is performed from the other surface of the SOI substrate to form a flexible portion having flexibility.
　本発明のように、５５０μｍ以上の厚みを有するＳＯＩ基板を用いてＰＺＴ膜を形成すれば、良質でほぼ均質なＰＺＴの結晶を得られることを発明者は見出した。その理由は、明確ではないが、ＰＺＴ膜を形成する際の加熱時の熱でＳＯＩ基板内の歪みの発生状況にあるものと発明者は考えている。本発明では、ＰＺＴ膜を形成した後、ＳＯＩ基板の他方の面に研磨加工を施してＳＯＩ基板を所望の厚みにするので、当初に厚みの厚いＳＯＩ基板を用いても、所望の厚みのＳＯＩ基板を備えたセンサ素子を形成できる。 The inventors have found that, when a PZT film is formed using an SOI substrate having a thickness of 550 μm or more as in the present invention, a high-quality and almost homogeneous PZT crystal can be obtained. The reason for this is not clear, but the inventor believes that there is distortion in the SOI substrate due to heat during heating when forming the PZT film. In the present invention, after the PZT film is formed, the other surface of the SOI substrate is polished to obtain a desired thickness. Therefore, even if a thick SOI substrate is used initially, the SOI substrate having the desired thickness is used. A sensor element provided with a substrate can be formed.
　エッチング処理によるＰＺＴ膜の形成は、ＳＯＩ基板の他方の面に研磨加工を施さない状態（粗い状態）で行なうのが好ましい。このようにすると、ＳＯＩ基板の他方の面から加わる熱が均等にＳＯＩ基板内に入るため、ＰＺＴ膜の均質な生成がさらに向上する。 The formation of the PZT film by the etching process is preferably performed in a state where the other surface of the SOI substrate is not polished (rough state). In this case, since the heat applied from the other surface of the SOI substrate enters the SOI substrate evenly, the uniform generation of the PZT film is further improved.
　ＳＯＩ基板の加熱の温度は５００～８００℃であるのが好ましい。加熱温度が５００℃を下回ると、ＰＺＴ膜を十分に形成することができない。また、加熱温度が８００℃を上回ると、Ｐｂの蒸発により所望の組成比を得られなくなる。ＳＯＩ基板の厚み寸法は、５５０～７５０μｍとするのが望ましいが、その上限は、加熱温度の影響を考慮すると自ずと定まるものであり、必要以上の厚みにする必要はない。 The temperature for heating the SOI substrate is preferably 500 to 800 ° C. If the heating temperature is below 500 ° C., the PZT film cannot be formed sufficiently. On the other hand, when the heating temperature exceeds 800 ° C., a desired composition ratio cannot be obtained due to evaporation of Pb. The thickness dimension of the SOI substrate is desirably 550 to 750 μm, but the upper limit is naturally determined in consideration of the influence of the heating temperature, and it is not necessary to make the thickness more than necessary.
　ＳＯＩ基板を他方の面から研磨加工及びエッチング処理する際は、ＳＯＩ基板を一方の面側からチャックする必要がある。静電チャックは、基板を均一に冷却して固定できる、静電チャックを用いることが好ましい。しかしながら単純に静電チャックを用いると、ＰＺＴ膜が帯電して膜破壊が発生し、各層との密着強度が低下する。その結果、所望の圧電特性が得られなくなる。そこで上部電極と下部電極とを同電位にした状態で、ＳＯＩ基板を上部電極側から静電チャックにより保持するのが望ましい。なお、静電チャックは、公知のものを用いればよい。上部電極と下部電極とを同電位にすると、ＰＺＴ膜は帯電し難いので、ＰＺＴ膜の特性が影響を受け難くなる。 When polishing and etching an SOI substrate from the other surface, it is necessary to chuck the SOI substrate from one surface side. The electrostatic chuck is preferably an electrostatic chuck that can cool and fix the substrate uniformly. However, when an electrostatic chuck is simply used, the PZT film is charged and film breakage occurs, and the adhesion strength with each layer decreases. As a result, desired piezoelectric characteristics cannot be obtained. Therefore, it is desirable to hold the SOI substrate by the electrostatic chuck from the upper electrode side with the upper electrode and the lower electrode at the same potential. A known electrostatic chuck may be used. When the upper electrode and the lower electrode are set to the same potential, the PZT film is difficult to be charged, so that the characteristics of the PZT film are hardly affected.
　なお、上述のようにＳＯＩ基板を上部電極側から静電チャックを行ってＳＯＩ基板を保持すると、静電チャックから受ける電圧によって、ＰＺＴ膜パターンの上部電極パターンが形成された部分と形成されない部分とで異なる電界が発生する。その結果、ＰＺＴ膜パターンに歪みが生じて、ＰＺＴ膜パターンの膜破裂または各層との密着強度の低下が起きるおそれがある。そこで、ＰＺＴ膜パターンを形成した後、すぐに上部電極を形成せず、可撓部を形成するための研磨加工およびエッチング処理をしてから上部電極を形成してもよい。この場合は、まずＰＺＴ膜パターンの上に上部電極を形成するための上部電極材料層を形成する。その後、上述のように研磨加工によりＳＯＩ基板の厚みを所定の厚みまで薄くし、エッチング処理により可撓部を形成する。そして、ＰＺＴ膜パターン上に形成された上部電極材料層にエッチング処理を施して、ＰＺＴ膜パターンの上に所定のパターンの上部電極を形成する。 As described above, when the SOI substrate is held by performing electrostatic chucking on the SOI substrate from the upper electrode side, a portion of the PZT film pattern on which the upper electrode pattern is formed and a portion on which the upper electrode pattern is not formed by the voltage received from the electrostatic chuck A different electric field is generated. As a result, the PZT film pattern is distorted, and the PZT film pattern may be ruptured or the adhesion strength with each layer may be reduced. Therefore, after the PZT film pattern is formed, the upper electrode may not be formed immediately, but the upper electrode may be formed after polishing and etching for forming the flexible portion. In this case, first, an upper electrode material layer for forming an upper electrode is formed on the PZT film pattern. Thereafter, the thickness of the SOI substrate is reduced to a predetermined thickness by polishing as described above, and the flexible portion is formed by etching. Then, the upper electrode material layer formed on the PZT film pattern is etched to form an upper electrode having a predetermined pattern on the PZT film pattern.
　この場合も、ＳＯＩ基板を他方の面から研磨加工及びエッチング処理する際に、上部電極材料層と下部電極とを同電位にした状態で、ＳＯＩ基板を上部電極材料層側から静電チャックにより保持すればよい。 Also in this case, when polishing and etching the SOI substrate from the other surface, the SOI substrate is held from the upper electrode material layer side by the electrostatic chuck while the upper electrode material layer and the lower electrode are at the same potential. do it.
　このようにＰＺＴ膜パターン上に上部電極材料層を形成した状態で、上部電極材料層側から静電チャックを行うと、ＰＺＴ膜パターン内の電界が一定になって、膜破裂等の原因となる歪みが生じ難くなるため、安定したＰＺＴ膜パターンを形成することができる。 When electrostatic chucking is performed from the upper electrode material layer side in a state where the upper electrode material layer is formed on the PZT film pattern in this way, the electric field in the PZT film pattern becomes constant and causes film rupture or the like. Since distortion hardly occurs, a stable PZT film pattern can be formed.
　上部電極と下部電極とを同電位にするには、種々の構造を採用できる。例えば、上部電極は、下部電極の出力を取り出す下部電極出力電極を含むように形成できる。この場合、ＰＺＴ膜パターンを厚み方向に貫通する貫通孔内に上部電極と一緒に形成されて下部電極出力電極と下部電極とを接続する貫通導電部と、ＰＺＴ膜パターン上に上部電極と一緒に形成されて下部電極出力電極と他の上部電極とを接続する表面導電部とによって同電位にした状態を形成することができる。このようにすれば、貫通導電部と表面導電部とによって下部電極と上部電極全体とを電気的に接続して同電位にすることができる。貫通導電部及び表面導電部は、上部電極と一緒に形成されるので、容易に上部電極と下部電極とを同電位にできる。 Various structures can be adopted to make the upper electrode and the lower electrode have the same potential. For example, the upper electrode can be formed to include a lower electrode output electrode that extracts the output of the lower electrode. In this case, a through-conductive portion that is formed together with the upper electrode in a through-hole penetrating the PZT film pattern in the thickness direction and connects the lower electrode output electrode and the lower electrode, and together with the upper electrode on the PZT film pattern It is possible to form a state in which the same potential is formed by the surface conductive portion that is formed and connects the lower electrode output electrode and the other upper electrode. If it does in this way, a lower electrode and the whole upper electrode can be electrically connected by the penetration conductive part and a surface conductive part, and it can be made the same electric potential. Since the through conductive portion and the surface conductive portion are formed together with the upper electrode, the upper electrode and the lower electrode can be easily set to the same potential.
　なお、エッチング処理後には、下部電極出力電極を除く上部電極と下部電極との同電位の状態を解除する必要がある。そのため、ＳＯＩ基板をエッチングするまでは、多数個取り用基板を用いて複数のセンサ素子を形成し、多数個取り用基板を分割する際に表面導電部を非導通状態にするのが好ましい。このようにすれば、多数個取り用基板を用いてセンサ素子を量産できる上、多数個取り用基板を分割すると同時に同電位状態を解除できる。 In addition, after the etching process, it is necessary to cancel the same potential state of the upper electrode and the lower electrode excluding the lower electrode output electrode. Therefore, until the SOI substrate is etched, it is preferable that a plurality of sensor elements are formed using the multi-cavity substrate, and the surface conductive portion is made non-conductive when the multi-cavity substrate is divided. In this way, the sensor elements can be mass-produced using the multi-piece substrate, and the same potential state can be released at the same time as the multi-piece substrate is divided.
本発明の実施の形態の方法で製造したセンサ素子（角速度センサ）の平面図である。It is a top view of the sensor element (angular velocity sensor) manufactured with the method of the embodiment of the invention. 図１のII－II線断面図である。FIG. 2 is a sectional view taken along line II-II in FIG. （Ａ）～（Ｆ）は、本発明の実施の形態の製造方法の一例を示す工程図である。(A)-(F) are process drawings which show an example of the manufacturing method of embodiment of this invention. 本発明の実施の形態の製造方法を説明するための図である。It is a figure for demonstrating the manufacturing method of embodiment of this invention. 図３（Ａ）～（Ｆ）に示す方法で製造した実施例のセンサ素子のＰＺＴ膜の成分のＸ線回折図である。FIG. 4 is an X-ray diffraction pattern of components of a PZT film of the sensor element of the example manufactured by the method shown in FIGS. 3 (A) to (F). 比較例のセンサ素子のＰＺＴ膜の成分のＸ線回折図である。It is a X-ray diffraction pattern of the component of the PZT film | membrane of the sensor element of a comparative example. （Ａ）～（Ｆ）は、本発明の実施の形態の製造方法の他の一例を示す工程図である。FIGS. 4A to 4F are process diagrams showing another example of the manufacturing method according to the embodiment of the present invention.
　以下、図面を参照して本発明の実施の形態を詳細に説明する。図１は、本発明の実施の形態の方法で製造したＰＺＴ膜を備えたセンサ素子（圧電型角速度センサ）１の平面図であり、図２は図１のII－II線断面図である。図２に示すように、本例の角速度センサ１は、センサ本体３と検出部５とを有している。センサ本体３は、中心部に円柱状の重錘７が位置し、外周部に筒状の支持部９が位置し、重錘７と支持部９との間に可撓性を有する可撓部１１を有するようにＳＯＩ基板にエッチングが施されて形成されている。センサ本体３の厚み寸法Ｌ１は約４０５μｍである。なお、図２は理解を容易にするため、検出部５及び可撓部１１は、厚み寸法を誇張して描いている。図２において、符号１０はＳｉ層であり、１７はＳｉの活性層であり、１３は酸化膜からなる絶縁層であり、１５はＳｉＯ２層である。重錘７及び支持部９は、Ｓｉ層１０が加工されて構成されている。可撓部１１は、絶縁層１３と活性層１７とＳｉＯ２層１５とから構成されている。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a sensor element (piezoelectric angular velocity sensor) 1 having a PZT film manufactured by the method of the embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. As shown in FIG. 2, the angular velocity sensor 1 of this example includes a sensor main body 3 and a detection unit 5. The sensor body 3 has a cylindrical weight 7 positioned at the center, a cylindrical support 9 positioned on the outer periphery, and a flexible portion having flexibility between the weight 7 and the support 9. 11 is formed by etching the SOI substrate. The thickness L1 of the sensor body 3 is about 405 μm. In FIG. 2, for easy understanding, the detection unit 5 and the flexible unit 11 are drawn with exaggerated thickness dimensions. In FIG. 2, reference numeral 10 denotes an Si layer, 17 denotes an Si active layer, 13 denotes an insulating layer made of an oxide film, and 15 denotes an SiO 2 layer. The weight 7 and the support portion 9 are configured by processing the Si layer 10. The flexible portion 11 includes an insulating layer 13, an active layer 17, and a SiO 2 layer 15.
　検出部５は、絶縁層１３の上に形成された下部電極Ｅ０と、下部電極Ｅ０の上に形成されたＰＺＴ膜パターン１９と、ＰＺＴ膜パターン１９の上に形成されて下部電極Ｅ０と対向する上部電極Ｅ１とから形成されている。ＰＺＴ膜パターン１９は、Ｐｂ１．３（Ｚｒ０．５２Ｔｉ０．４８）ＯＸをターゲットとするスパッタにより形成されたＰＺＴからなり、３μｍの厚み寸法を有している。上部電極Ｅ１は、ＴｉとＡｕとの積層薄膜から構成されている。下部電極Ｅ０は、主として可撓部１１上に形成されており、ＴｉとＰｔとの積層薄膜から構成されている。上部電極Ｅ１は、表面電荷の変化により角速度を検出する複数の検出用電極Ｅ１１と、重錘７を振動させるために用いる複数の駆動用電極Ｅ１２と、下部電極出力電極Ｅ１３とを含んでいる。下部電極出力電極Ｅ１３は、ＰＺＴ膜パターン１９を厚み方向に貫通する貫通孔１９ａ内に形成された貫通導電部２１によって下部電極Ｅ０と電気的に接続されており、下部電極Ｅ０の出力を取り出す役割を果たしている。 The detection unit 5 is formed on the lower electrode E0 formed on the insulating layer 13, the PZT film pattern 19 formed on the lower electrode E0, and the PZT film pattern 19, and faces the lower electrode E0. The upper electrode E1 is formed. The PZT film pattern 19 is made of PZT formed by sputtering using Pb 1.3 (Zr 0.52 Ti 0.48 ) O X as a target, and has a thickness dimension of 3 μm. The upper electrode E1 is composed of a laminated thin film of Ti and Au. The lower electrode E0 is mainly formed on the flexible portion 11, and is composed of a laminated thin film of Ti and Pt. The upper electrode E1 includes a plurality of detection electrodes E11 that detect an angular velocity by a change in surface charge, a plurality of drive electrodes E12 that are used to vibrate the weight 7, and a lower electrode output electrode E13. The lower electrode output electrode E13 is electrically connected to the lower electrode E0 by a through conductive portion 21 formed in a through hole 19a penetrating the PZT film pattern 19 in the thickness direction, and takes out the output of the lower electrode E0. Plays.
　次に本発明のセンサ素子（角速度センサ１）の製造方法の一例について、図３の工程図を用いて説明する。まず、図３（Ａ）に示すように、多数個取り用基板となるＳＯＩ基板３１を用意する。なお、図３は、便宜的に多数個取り用基板に含まれる１つのセンサ素子の断面を示している。ＳＯＩ基板３１は、Ｓｉ層１０′及びＳｉの活性層１７′の間にＳｉＯ２層１５′が挿入された構造を有している。Ｓｉの活性層１７′には、活性化処理がなされている。Ｓｉ基板１０′の下面には酸化膜からなる絶縁層３３が形成されており、Ｓｉの活性層１７′の上にも酸化膜からなる絶縁層１３′が形成されている。本例で用いたＳＯＩ基板３１の厚み寸法Ｌ２は、約６２５μｍである（図３（Ａ）参照）。なお、ＳＯＩ基板３１の厚み寸法Ｌ２は、５５０～７５０μｍが望ましい。 Next, an example of a method for manufacturing the sensor element (angular velocity sensor 1) of the present invention will be described with reference to the process diagram of FIG. First, as shown in FIG. 3A, an SOI substrate 31 serving as a multi-piece substrate is prepared. FIG. 3 shows a cross section of one sensor element included in a multi-piece substrate for convenience. The SOI substrate 31 has a structure in which a SiO 2 layer 15 ′ is inserted between the Si layer 10 ′ and the Si active layer 17 ′. The Si active layer 17 'is activated. An insulating layer 33 made of an oxide film is formed on the lower surface of the Si substrate 10 ', and an insulating layer 13' made of an oxide film is also formed on the Si active layer 17 '. The thickness dimension L2 of the SOI substrate 31 used in this example is about 625 μm (see FIG. 3A). The thickness dimension L2 of the SOI substrate 31 is preferably 550 to 750 μm.
　次に、図３（Ｂ）に示すように、ＳＯＩ基板３１の一方の面上（絶縁層１３′）の上に下部電極Ｅ０を形成する。下部電極Ｅ０は、ＳＯＩ基板３１の一方の面上に厚み２０ｎｍのＴｉ膜をスパッタにより形成してからＴｉ膜を酸化処理し、その上に厚み１００ｎｍのＰｔ膜をスパッタにより形成して構成する。 Next, as shown in FIG. 3B, a lower electrode E0 is formed on one surface (insulating layer 13 ′) of the SOI substrate 31. The lower electrode E0 is formed by forming a 20 nm thick Ti film on one surface of the SOI substrate 31 by sputtering, oxidizing the Ti film, and forming a 100 nm thick Pt film thereon by sputtering.
　次に、図３（Ｃ）に示すように、ＳＯＩ基板３１をヒータＨ上に載置して、ＳＯＩ基板３１の他方の面側からＳＯＩ基板３１を約７００℃で加熱した状態で、下部電極Ｅ０上にＰＺＴ膜３７を形成する。具体的には、Ｐｂ１．３（Ｚｒ０．５２Ｔｉ０．４８）ＯＸをターゲットとしてスパッタにより厚み３μｍのＰＺＴ膜３７を形成する。加熱温度は５００～８００℃が望ましい。このＰＺＴ膜３７の形成工程は、ＳＯＩ基板３１の他方の面に研磨加工を施さない状態（粗い状態）で行なう。 Next, as shown in FIG. 3C, the SOI substrate 31 is placed on the heater H, and the lower electrode is heated in a state where the SOI substrate 31 is heated at about 700 ° C. from the other surface side of the SOI substrate 31. A PZT film 37 is formed on E0. Specifically, a PZT film 37 having a thickness of 3 μm is formed by sputtering using Pb 1.3 (Zr 0.52 Ti 0.48 ) O X as a target. The heating temperature is preferably 500 to 800 ° C. The step of forming the PZT film 37 is performed in a state where the other surface of the SOI substrate 31 is not polished (rough state).
　次に、ＰＺＴ膜３７の上に図示しないレジスト膜を形成した後、ウエットエッチング処理を施して、図３（Ｄ）に示すように、貫通孔１９ａを含む所定の形状のＰＺＴ膜パターン１９を形成する。 Next, after forming a resist film (not shown) on the PZT film 37, a wet etching process is performed to form a PZT film pattern 19 having a predetermined shape including a through hole 19a as shown in FIG. To do.
　次に、図３（Ｅ）に示すように、上部電極材料層３９及び貫通導電部２１を形成する。貫通導電部２１は、下部電極Ｅ０とを接続するように、貫通孔１９ａ内に上部電極材料層３９と一緒に形成する。上部電極材料層３９及び貫通導電部２１は、ＰＺＴ膜パターン１９を含めて一方の面上に全面的に厚み２０ｎｍのＴｉ膜をスパッタにより形成してからＴｉ膜を酸化処理し、その上に厚み３００ｎｍのＡｕ膜をスパッタにより形成して構成する。 Next, as shown in FIG. 3E, the upper electrode material layer 39 and the through conductive portion 21 are formed. The through conductive portion 21 is formed together with the upper electrode material layer 39 in the through hole 19a so as to connect to the lower electrode E0. The upper electrode material layer 39 and the penetrating conductive portion 21 are formed by sputtering a Ti film having a thickness of 20 nm on one surface including the PZT film pattern 19 over the entire surface, and then oxidizing the Ti film. A 300 nm Au film is formed by sputtering.
　次に、上部電極材料層３９の上に図示しないフォトレジスト膜を形成し、所定パターンのレジスト膜が形成された上部電極材料層３９にイオンビームエッチングを施して、図３（Ｆ）に示すように、上部電極Ｅ１を形成する。その後、レジスト膜を除去する。上部電極Ｅ１のパターンは、複数の検出用電極Ｅ１１と複数の駆動用電極Ｅ１２と下部電極出力電極Ｅ１３とを含んでいる。下部電極出力電極Ｅ１３は、貫通導電部２１により下部電極Ｅ０と電気的に接続されている。図４は、上部電極Ｅ１を形成した後の多数個取り用基板の平面図である。 Next, a photoresist film (not shown) is formed on the upper electrode material layer 39, and ion beam etching is performed on the upper electrode material layer 39 on which a resist film having a predetermined pattern is formed, as shown in FIG. Then, the upper electrode E1 is formed. Thereafter, the resist film is removed. The pattern of the upper electrode E1 includes a plurality of detection electrodes E11, a plurality of drive electrodes E12, and a lower electrode output electrode E13. The lower electrode output electrode E13 is electrically connected to the lower electrode E0 through the through conductive portion 21. FIG. 4 is a plan view of the multi-piece substrate after the upper electrode E1 is formed.
　図４に示すように、下部電極出力電極Ｅ１３と他の上部電極（検出用電極Ｅ１１および駆動用電極Ｅ１２）とがＰＺＴ膜パターン１９上に形成された表面導電部４１により電気的に接続されている。このため、上部電極Ｅ１の形成後においては、下部電極Ｅ０と上部電極Ｅ１は、電気的に接続されている。 As shown in FIG. 4, the lower electrode output electrode E13 and other upper electrodes (detection electrode E11 and drive electrode E12) are electrically connected by the surface conductive portion 41 formed on the PZT film pattern 19. Yes. For this reason, after formation of the upper electrode E1, the lower electrode E0 and the upper electrode E1 are electrically connected.
　次に、ＳＯＩ基板３１の他方の面に研磨加工を施して、ＳＯＩ基板３１の厚みをＰＺＴ膜の特性を有効に発揮させる所定の厚み（図２のＬ１の寸法：４０５μｍ）まで薄くする。研磨されたＳＯＩ基板３１の他方の面（裏面）はミラー状態になっている。そして、ＳＯＩ基板３１の他方の面からエッチング処理を施して、図２に示すような重錘７、支持部９及び可撓部１１を形成してセンサ本体３を作る。具体的には、図３（Ｆ）に示すように、ＳＯＩ基板３１を上部電極Ｅ１側から静電チャックＣにより保持する。そしてフォトリソ技術によるドライエッチングにより、ＳＯＩ基板３１の他方の面（裏面）からエッチング処理を施す。前述したように、下部電極Ｅ０と上部電極Ｅ１は、電気的に接続されているため、上部電極Ｅ１と下部電極Ｅ０とが同電位になった状態で、ＳＯＩ基板３１は、上部電極Ｅ１側から静電チャックＣにより保持されることになる。したがって静電チャックＣを利用しても、ＰＺＴ膜は帯電し難い。 Next, the other surface of the SOI substrate 31 is polished to reduce the thickness of the SOI substrate 31 to a predetermined thickness (L1 dimension in FIG. 2: 405 μm) that effectively exhibits the characteristics of the PZT film. The other surface (back surface) of the polished SOI substrate 31 is in a mirror state. Then, an etching process is performed from the other surface of the SOI substrate 31 to form the weight 7, the support portion 9, and the flexible portion 11 as shown in FIG. Specifically, as shown in FIG. 3F, the SOI substrate 31 is held by the electrostatic chuck C from the upper electrode E1 side. Then, an etching process is performed from the other surface (back surface) of the SOI substrate 31 by dry etching using a photolithography technique. As described above, since the lower electrode E0 and the upper electrode E1 are electrically connected, the SOI substrate 31 is viewed from the upper electrode E1 side while the upper electrode E1 and the lower electrode E0 are at the same potential. It is held by the electrostatic chuck C. Therefore, even if the electrostatic chuck C is used, the PZT film is hardly charged.
　次に、多数個取り用基板を分割する。分割の際に図４に示す破線Ｂに沿って分割されるため、表面導電部４１が非導通状態になる。これにより、検出用電極Ｅ１１及び駆動用電極Ｅ１２と下部電極Ｅ０との電気的接続が解除される。以上のステップにより、多数個取りによって、図１及び図２に示すセンサ素子（角速度センサ）１の製造を完了する。 Next, the multi-piece substrate is divided. Since the surface is divided along the broken line B shown in FIG. 4 at the time of division, the surface conductive portion 41 becomes non-conductive. As a result, the electrical connection between the detection electrode E11 and the drive electrode E12 and the lower electrode E0 is released. Through the above steps, the manufacture of the sensor element (angular velocity sensor) 1 shown in FIG. 1 and FIG.
　次に、上記のようにして製造したＰＺＴ膜形成時のＳＯＩ基板の厚み寸法とＰＺＴ膜の成分との関係を調べた。図５は、上記の方法で製造したセンサ素子（実施例）のＰＺＴ膜の中心部のＸ線回折（ＸＲＤ）図であり、図６はＰＺＴ膜形成時において厚みが薄いＳＯＩ基板（厚み寸法４００μｍのＳＯＩ基板）を用いて製造したセンサ素子（比較例）のＰＺＴ膜の中心部の成分のＸ線回折図である。図中において、例えば、ＰＺＴ（１００）は、結晶配向が（１００）のＰＺＴである。また、Ｐｙｒｏは、低温域で発生する不要なピークである。両図から求めたＰＺＴ（１００）／Ｐｙｒｏ及びＰＺＴ（１００）／ＰＺＴ（１１１）の強度比率を表１に示す。
Figure JPOXMLDOC01-appb-T000001
 Next, the relationship between the thickness dimension of the SOI substrate at the time of forming the PZT film manufactured as described above and the component of the PZT film was examined. FIG. 5 is an X-ray diffraction (XRD) diagram of the central portion of the PZT film of the sensor element (Example) manufactured by the above method, and FIG. 6 is an SOI substrate (thickness dimension: 400 μm) that is thin when the PZT film is formed. It is an X-ray diffraction pattern of the component of the center part of the PZT film | membrane of the sensor element (comparative example) manufactured using (SOI substrate). In the figure, for example, PZT (100) is PZT having a crystal orientation of (100). Pyro is an unnecessary peak that occurs in a low temperature range. Table 1 shows the intensity ratios of PZT (100) / Pyro and PZT (100) / PZT (111) determined from both figures.
Figure JPOXMLDOC01-appb-T000001
　表１において（Ｘ００）は、ＰＺＴ膜の中心部を示すものであり、（Ｘ４０）は、ＰＺＴ膜の中心部からＸ方向に４０ｍｍの位置を示すものである。センサ素子のＰＺＴ膜は、ＰＺＴ（１００）／Ｐｙｒｏ及びＰＺＴ（１００）／ＰＺＴ（１１１）が高いのが望ましい。表１より、（Ｘ００）及び（Ｘ４０）のいずれにおいても、実施例のＰＺＴ膜のＰＺＴ（１００）／Ｐｙｒｏ及びＰＺＴ（１００）／ＰＺＴ（１１１）は、比較例のものより大きいのが分る。 In Table 1, (X00) indicates the center of the PZT film, and (X40) indicates a position 40 mm in the X direction from the center of the PZT film. The PZT film of the sensor element preferably has a high PZT (100) / Pyro and PZT (100) / PZT (111). From Table 1, it can be seen that in both (X00) and (X40), PZT (100) / Pyro and PZT (100) / PZT (111) of the PZT film of the example are larger than those of the comparative example. .
　次に本発明のセンサ素子（角速度センサ１）の製造方法の他の一例について、図７の工程図を用いて説明する。図７において、図３と共通する部分については、図３に付した符号の数に１００の数を加えた数の符号を付して説明を省略する。図７に示す本発明の他の一例では、図７（Ａ）から（Ｅ）までは、図３に示す本発明の一例と同じ工程を実施する（図３（Ａ）～（Ｅ）参照）。その後、図７（Ｅ）に示すように上部電極材料層１３９を形成した後に、ＳＯＩ基板１３１を上部電極材料層１３９側から静電チャックＣ′により保持する。そして図７（Ｆ）では、上述したようなＳＯＩ基板１３１の他方の面（裏面）からエッチング処理を施す。 Next, another example of the manufacturing method of the sensor element (angular velocity sensor 1) of the present invention will be described with reference to the process diagram of FIG. In FIG. 7, parts common to FIG. 3 are given the same reference numerals as those shown in FIG. In another example of the present invention shown in FIG. 7, the same steps as those in the example of the present invention shown in FIG. 3 are carried out from FIGS. 7A to 7E (see FIGS. 3A to 3E). . Then, after forming the upper electrode material layer 139 as shown in FIG. 7E, the SOI substrate 131 is held by the electrostatic chuck C ′ from the upper electrode material layer 139 side. In FIG. 7F, an etching process is performed from the other surface (back surface) of the SOI substrate 131 as described above.
　この例では、下部電極Ｅ１００と上部電極材料層１３９は、電気的に接続されているため、上部電極材料層１３９と下部電極Ｅ１００とが同電位になった状態で、ＳＯＩ基板１３１は、上部電極材料層１３９側から静電チャックＣ′により保持されることになる。このように、図７の例では、上部電極のパターンを形成する前の上部電極材料層１３９の状態で静電チャックＣ′を行うため、図３の例のように上部電極のパターンが形成された部分と形成されない部分とで異なる電界が発生することはない。そのため、図７に示す製造工程を採用すれば、ＰＺＴ膜パターン１１９に歪みが生じ難くなり、ＰＺＴ膜パターン１１９の膜破裂または各層との密着強度の低下を確実に防止することができる。 In this example, since the lower electrode E100 and the upper electrode material layer 139 are electrically connected, the SOI substrate 131 is formed with the upper electrode material layer 139 and the lower electrode E100 at the same potential. It is held by the electrostatic chuck C ′ from the material layer 139 side. In this way, in the example of FIG. 7, since the electrostatic chuck C ′ is performed in the state of the upper electrode material layer 139 before forming the upper electrode pattern, the upper electrode pattern is formed as in the example of FIG. Different electric fields are not generated between the portions that are not formed and the portions that are not formed. Therefore, if the manufacturing process shown in FIG. 7 is adopted, it is difficult for the PZT film pattern 119 to be distorted, and it is possible to reliably prevent the PZT film pattern 119 from rupturing or lowering the adhesion strength with each layer.
　なお、上記の実施の形態は、角速度センサ（ジャイロ）の製造方法を示した例であるが、加速度センサ等の他のＰＺＴ膜を備えたセンサ素子を製造する場合にも本発明を適用できるのは勿論である。 In addition, although said embodiment is an example which showed the manufacturing method of an angular velocity sensor (gyro), this invention is applicable also when manufacturing the sensor element provided with other PZT films | membranes, such as an acceleration sensor. Of course.
　本発明によれば、５５０μｍ以上の厚みを有するＳＯＩ基板を用いてＰＺＴ膜を形成した後、ＳＯＩ基板を所望の厚みまで薄くするため、良質で均質なＰＺＴ膜を得ることができる。 According to the present invention, after forming a PZT film using an SOI substrate having a thickness of 550 μm or more, the SOI substrate is thinned to a desired thickness, so that a high-quality and uniform PZT film can be obtained.
　１　センサ素子（角速度センサ）
　３　センサ本体
　５　検出部
　１１，１１１　可撓部
　１９，１１９　ＰＺＴ膜パターン
　１９ａ　貫通孔
　２１　貫通導電部
　３１，１３１　ＳＯＩ基板
　３７　ＰＺＴ膜
　４１　表面導電部
　１３９　上部電極材料層
　Ｃ，Ｃ′　静電チャック
　Ｅ１　上部電極
　Ｅ０，Ｅ１００　下部電極
　Ｅ１３　下部電極出力電極 1 Sensor element (angular velocity sensor)
DESCRIPTION OF SYMBOLS 3 Sensor body 5 Detection part 11,111 Flexible part 19,119 PZT film | membrane pattern 19a Through-hole 21 Through-conductive part 31,131 SOI substrate 37 PZT film | membrane 41 Surface conductive part 139 Upper electrode material layer C, C 'Electrostatic chuck E1 Upper electrode E0, E100 Lower electrode E13 Lower electrode output electrode

Claims (8)

  1. 　５５０μｍ以上の厚みを有するＳＯＩ基板の一方の面上に下部電極を形成し、
    　前記ＳＯＩ基板の他方の面側から前記ＳＯＩ基板を加熱した状態で、前記下部電極の上にＰＺＴ膜を形成し、
    　前記ＰＺＴ膜にエッチング処理を施して所定のＰＺＴ膜パターンを形成し、
    　前記ＰＺＴ膜パターンの上に前記下部電極と対向する所定のパターンの上部電極を形成し、
    　前記ＳＯＩ基板の前記他方の面に研磨加工を施して、前記ＳＯＩ基板の厚みを前記ＰＺＴ膜パターンの特性を有効に発揮させる所定の厚みまで薄くし、
    　その後、前記ＳＯＩ基板の前記他方の面からエッチング処理を施して可撓性を有する可撓部を形成することを特徴とするＰＺＴ膜を備えたセンサ素子の製造方法。     Forming a lower electrode on one surface of an SOI substrate having a thickness of 550 μm or more;
    In a state where the SOI substrate is heated from the other surface side of the SOI substrate, a PZT film is formed on the lower electrode,
    Etching the PZT film to form a predetermined PZT film pattern,
    Forming an upper electrode of a predetermined pattern facing the lower electrode on the PZT film pattern;
    Polishing the other surface of the SOI substrate to reduce the thickness of the SOI substrate to a predetermined thickness that effectively exhibits the characteristics of the PZT film pattern;
    Then, the manufacturing method of the sensor element provided with the PZT film | membrane characterized by performing an etching process from the said other surface of the said SOI substrate, and forming the flexible part which has flexibility.
  2. 　前記エッチング処理は、前記ＳＯＩ基板の他方の面に研磨加工を施さない状態で行なうことを特徴とする請求項１に記載のＰＺＴ膜を備えたセンサ素子の製造方法。 2. The method of manufacturing a sensor element having a PZT film according to claim 1, wherein the etching process is performed without polishing the other surface of the SOI substrate.
  3. 　前記ＳＯＩ基板の加熱の温度が５００～８００℃であり、
    　前記ＳＯＩ基板の厚み寸法が５５０～７５０μｍであることを特徴とする請求項２に記載のＰＺＴ膜を備えたセンサ素子の製造方法。     The heating temperature of the SOI substrate is 500 to 800 ° C .;
    3. The method of manufacturing a sensor element having a PZT film according to claim 2, wherein the thickness dimension of the SOI substrate is 550 to 750 μm.
  4. 　前記ＳＯＩ基板を前記他方の面から研磨加工及びエッチング処理する際に、前記上部電極と前記下部電極とを同電位にした状態で、前記ＳＯＩ基板を前記上部電極側から静電チャックにより保持することを特徴とする請求項２に記載のＰＺＴ膜を備えたセンサ素子の製造方法。 When polishing and etching the SOI substrate from the other surface, the SOI substrate is held from the upper electrode side by an electrostatic chuck in a state where the upper electrode and the lower electrode are at the same potential. The manufacturing method of the sensor element provided with the PZT film | membrane of Claim 2 characterized by these.
  5. 　前記上部電極は、前記下部電極の出力を取り出す下部電極出力電極を含んでおり、
    　前記ＰＺＴ膜パターンを厚み方向に貫通する貫通孔内に前記上部電極と一緒に形成されて前記下部電極出力電極と前記下部電極とを接続する貫通導電部と、前記ＰＺＴ膜パターン上に前記上部電極と一緒に形成されて前記下部電極出力電極と他の前記上部電極とを接続する表面導電部とによって前記同電位にした状態が形成されていることを特徴とする請求項４に記載のＰＺＴ膜を備えたセンサ素子の製造方法。     The upper electrode includes a lower electrode output electrode that extracts the output of the lower electrode,
    A through-conductive portion that is formed together with the upper electrode in a through-hole penetrating the PZT film pattern in the thickness direction and connects the lower electrode output electrode and the lower electrode; and the upper electrode on the PZT film pattern 5. The PZT film according to claim 4, wherein the same electric potential is formed by a surface conductive portion formed together with the lower electrode output electrode and the other upper electrode. A method for manufacturing a sensor element comprising:
  6. 　前記ＳＯＩ基板をエッチングするまでは、多数個取り用基板を用いて複数のセンサ素子を形成し、
    　前記多数個取り用基板を分割する際に前記表面導電部を非導通状態にすることを特徴とする請求項５に記載のＰＺＴ膜を備えたセンサ素子の製造方法。     Until the SOI substrate is etched, a plurality of sensor elements are formed using a large number of substrates.
    6. The method of manufacturing a sensor element having a PZT film according to claim 5, wherein the surface conductive portion is brought into a non-conductive state when the multi-piece substrate is divided.
  7. 　５５０μｍ以上の厚みを有するＳＯＩ基板の一方の面上に下部電極を形成し、
    　前記ＳＯＩ基板の他方の面側から前記ＳＯＩ基板を加熱した状態で、前記下部電極の上にＰＺＴ膜を形成し、
    　前記ＰＺＴ膜にエッチング処理を施して所定のＰＺＴ膜パターンを形成し、
    　前記ＰＺＴ膜パターンの上に前記下部電極と対向する上部電極を形成するための上部電極材料層を形成し、
    　前記ＳＯＩ基板の前記他方の面に研磨加工を施して、前記ＳＯＩ基板の厚みを前記ＰＺＴ膜パターンの特性を有効に発揮させる所定の厚みまで薄くし、
    　その後、前記ＳＯＩ基板の前記他方の面からエッチング処理を施して可撓性を有する可撓部を形成し、
    　前記上部電極材料層にエッチング処理を施して前記ＰＺＴ膜パターンの上に所定のパターンの前記上部電極を形成することを特徴とするＰＺＴ膜を備えたセンサ素子の製造方法。     Forming a lower electrode on one surface of an SOI substrate having a thickness of 550 μm or more;
    In a state where the SOI substrate is heated from the other surface side of the SOI substrate, a PZT film is formed on the lower electrode,
    Etching the PZT film to form a predetermined PZT film pattern,
    Forming an upper electrode material layer on the PZT film pattern to form an upper electrode facing the lower electrode;
    Polishing the other surface of the SOI substrate to reduce the thickness of the SOI substrate to a predetermined thickness that effectively exhibits the characteristics of the PZT film pattern;
    Thereafter, an etching process is performed from the other surface of the SOI substrate to form a flexible portion having flexibility,
    A method of manufacturing a sensor element having a PZT film, wherein the upper electrode material layer is etched to form the upper electrode having a predetermined pattern on the PZT film pattern.
  8. 　前記ＳＯＩ基板を前記他方の面から研磨加工及びエッチング処理する際に、前記上部電極材料層と前記下部電極とを同電位にした状態で、前記ＳＯＩ基板を前記上部電極材料層側から静電チャックにより保持することを特徴とする請求項７に記載のＰＺＴ膜を備えたセンサ素子の製造方法。 When polishing and etching the SOI substrate from the other surface, the SOI substrate is electrostatic chucked from the upper electrode material layer side with the upper electrode material layer and the lower electrode at the same potential. The method of manufacturing a sensor element having a PZT film according to claim 7, wherein
PCT/JP2011/055470 2010-03-12 2011-03-09 Manufacturing method for sensor element equipped with pzt film WO2011111732A1 (en)

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