WO2012165110A1 - Film ferroélectrique et élément piézoélectrique le comprenant - Google Patents

Film ferroélectrique et élément piézoélectrique le comprenant Download PDF

Info

Publication number
WO2012165110A1
WO2012165110A1 PCT/JP2012/061854 JP2012061854W WO2012165110A1 WO 2012165110 A1 WO2012165110 A1 WO 2012165110A1 JP 2012061854 W JP2012061854 W JP 2012061854W WO 2012165110 A1 WO2012165110 A1 WO 2012165110A1
Authority
WO
WIPO (PCT)
Prior art keywords
crystal
ferroelectric film
film
piezoelectric
domain
Prior art date
Application number
PCT/JP2012/061854
Other languages
English (en)
Japanese (ja)
Inventor
健児 馬渡
Original Assignee
コニカミノルタホールディングス株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by コニカミノルタホールディングス株式会社 filed Critical コニカミノルタホールディングス株式会社
Publication of WO2012165110A1 publication Critical patent/WO2012165110A1/fr

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14233—Structure of print heads with piezoelectric elements of film type, deformed by bending and disposed on a diaphragm
    • 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
    • H10N30/704—Piezoelectric or electrostrictive devices based on piezoelectric or electrostrictive films or coatings
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00—Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01—Embodiments of or processes related to ink-jet heads
    • B41J2202/03—Specific materials used
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L28/00—Passive two-terminal components without a potential-jump or surface barrier for integrated circuits; Details thereof; Multistep manufacturing processes therefor
    • H01L28/40—Capacitors
    • H01L28/55—Capacitors with a dielectric comprising a perovskite structure material
    • 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
    • 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

Definitions

  • the present invention relates to a ferroelectric film made of a perovskite crystal and a piezoelectric element provided with the ferroelectric film.
  • piezoelectric materials such as Pb (Zr, Ti) O 3 have been used as electromechanical transducers for application to drive elements and sensors.
  • Such a piezoelectric body is expected to be applied to a MEMS (Micro Electro Mechanical Systems) element by being formed as a thin film on a substrate such as Si.
  • MEMS Micro Electro Mechanical Systems
  • the cost can be greatly reduced by manufacturing the elements at a high density on a relatively large Si wafer having a diameter of 6 inches or 8 inches, compared to single wafer manufacturing in which the elements are individually manufactured. it can.
  • the piezoelectric thin film and making the device MEMS the mechanical and electrical conversion efficiency is improved, and new added value such as improved sensitivity and characteristics of the device is also created.
  • a thermal sensor it is possible to increase measurement sensitivity by reducing thermal conductance due to MEMS, and in an inkjet head for a printer, high-definition patterning can be achieved by increasing the density of nozzles.
  • a crystal made of Pb, Zr, Ti, and O called PZT is often used. Since PZT exhibits a good piezoelectric effect when it has an ABO 3 type perovskite structure shown in FIG. 8, it needs to be a perovskite single phase.
  • the shape of the unit cell of the PZT crystal having the perovskite structure varies depending on the ratio of Ti and Zr, which are atoms entering the B site. That is, when Ti is large, the crystal lattice of PZT is tetragonal, and when Zr is large, the crystal lattice of PZT is rhombohedral.
  • the piezoelectric thin film When a piezoelectric thin film is used as a MEMS drive element, the piezoelectric thin film must be formed with a thickness of 3 to 5 ⁇ m in order to satisfy the required displacement generation force.
  • a chemical film-forming method such as a CVD method, a physical method such as a sputtering method or an ion plating method, and a liquid phase growth method such as a sol-gel method are known. It is important to find the conditions for obtaining a perovskite single phase film according to the film forming method.
  • a MEMS driving element with higher density and higher output has been demanded.
  • a ferroelectric film is required that can obtain a value (absolute value) of 150 [pm / V] or more as the value (absolute value) of the piezoelectric constant d 31 that is an index of piezoelectric characteristics. It is done.
  • the piezoelectric constant d 31 can be calculated by the following formula 1, which is disclosed in Non-Patent Document 1, for example.
  • Perovskite crystal materials such as PZT are ferroelectrics having spontaneous polarization Ps when no voltage is applied.
  • the polarization domain refers to a region where the directions of spontaneous polarization Ps are aligned.
  • the direction that the spontaneous polarization Ps can take varies depending on the shape of the unit cell of the crystal. If it is tetragonal, it is the ⁇ 100> axial direction, and if it is rhombohedral, it is the ⁇ 111> axial direction. Note that the ⁇ 100> axial direction collectively refers to [100], [010], [001] and a total of six equivalent directions opposite to these directions.
  • the ⁇ 111> axis direction collectively refers to [111], [ ⁇ 111], [1-11], [ ⁇ 1-11], and a total of eight equivalent directions opposite to these directions.
  • . 9A shows the direction of tetragonal spontaneous polarization Ps
  • FIG. 9B shows the direction of rhombohedral spontaneous polarization Ps.
  • a domain composed of the spontaneous polarization Ps in the [100] direction and the [010] direction and the opposite direction thereof is called an a-axis orientation domain
  • the spontaneous polarization in the [001] direction and the opposite direction thereof A domain composed of Ps is called a c-axis orientation domain.
  • the boundary between domains is called a domain wall.
  • domain walls There are two types of domain walls: 180 ° domain walls and non-180 ° domain walls.
  • the former 180 ° domain wall is the boundary between a domain in one direction and a domain in its inverted direction.
  • non-180 ° domain wall is a boundary between domains in directions other than 180 °.
  • a domain wall in which an a-axis orientation domain and a c-axis orientation domain are adjacent to each other in a tetragonal crystal can be given.
  • the domain wall at this time becomes a boundary between domains whose orientation directions are different from each other by 90 °.
  • FIG. 10 shows a piezoelectric strain ⁇ X1 when an electric field is applied in the c-axis direction to a tetragonal c-axis orientation domain, and the same electric field in the c-axis direction with respect to a tetragonal a-axis orientation domain.
  • the piezoelectric strain ⁇ X2 when applied is shown.
  • a thick black arrow indicates the polarization direction (the same applies to other drawings).
  • the 90 ° domain rotation from the a-axis direction to the c-axis direction is larger than the piezoelectric strain ⁇ X1 (normal piezoelectric strain) when an electric field is applied to the c-axis orientation domain in the c-axis direction. Since ⁇ X2 is generated, if such non-180 ° domain rotation can be efficiently generated, the piezoelectric characteristics can be improved.
  • Non-180 ° domain rotation is considered to occur by the following mechanism. As shown in FIG. 11, it is assumed that a domain 101 whose polarization direction is in the direction of electric field application and a non-180 ° domain 102 in a different direction are in contact with each other by a non-180 ° domain wall W. . When an electric field is applied, first, the domain 101 generates a normal piezoelectric strain, and is dragged by this strain, so that the polarization direction of the adjacent non-180 ° domain 102 is rotated in the electric field application direction via the non-180 ° domain wall W.
  • Non-180 ° domain rotation is caused to improve the piezoelectric characteristics.
  • the piezoelectric distortion is reversibly generated by applying / not applying an electric field, and non-180 ° domain rotation applies an electric field over a certain level (for example, 400 V / mm or more in FIG. 12). Occurs. At this time, the sum of the normal piezoelectric strain (true piezoelectric strain) due to the c-axis orientation domain and the piezoelectric strain due to non-180 ° domain rotation is observed as the total piezoelectric strain (electric field induced strain amount).
  • a thin film has a crystal grain size smaller than that of a bulk except in special cases such as an epitaxial film.
  • the crystal in a ferroelectric film formed on Si via a lower electrode such as Pt or Ir, the crystal has a columnar structure and the average crystal grain size is about 100 to 500 nm. If the crystal grain size is small, as shown in Non-Patent Document 2, the number of domains entering the crystal is reduced, and the number of domain walls is also reduced accordingly, which causes non-180 ° domain rotation. It becomes difficult. As a result, it becomes difficult to improve the piezoelectric characteristics.
  • FIG. 13A is a plan view showing a set of a plurality of crystal grains having different grain sizes
  • FIGS. 13B and 13C are small grain sizes included in the plurality of crystal grains.
  • FIGS. 13D and 13E are a plan view and a cross-sectional view of a crystal grain 201 (for example, a grain size of 0.3 ⁇ m or less).
  • FIGS. 13D and 13E show a crystal grain 202 having a large grain size included in the plurality of crystal grains. It is the top view and sectional drawing of (for example, a particle size of 1 micrometer or less).
  • the small crystal grains 201 constituting the thin film have fewer domains and domain walls than the large crystal grains 202.
  • the grain size of the crystal grain 201 is small, the number of non-180 ° domain walls W1 that are the starting point of non-180 ° domain rotation is extremely lower than that of the crystal grain 202, and the domain wall is 180 ° domain.
  • the wall W2 alone is used. For this reason, in a thin film having a small crystal grain size, it is difficult to improve the piezoelectric characteristics by causing non-180 ° domain rotation.
  • the thin film can be epitaxially grown using the crystal orientation of the substrate, or the crystal can be oriented due to the relationship between the stress of the substrate and the film.
  • a device for causing non-180 ° domain rotation in a thin film has been made by using these.
  • Patent Document 1 a ⁇ 100> -oriented tetragonal epitaxial film is grown on a substrate, and an a-axis orientation domain and a c-axis orientation domain are mixed in this epitaxial film, so that non-180 ° Domain rotation is caused to enhance the piezoelectric characteristics.
  • Non-Patent Document 3 discloses that the epitaxial film becomes a tetragonal single crystal even with the MPB composition.
  • Patent Document 2 a non-180 ° domain wall is obtained by obtaining an a-axis single alignment film in which the alignment axis is inclined from the vertical direction of the substrate using a special Si substrate in which the crystal plane of the substrate surface is inclined.
  • domain rotation is generated at a relatively low voltage.
  • JP 2008-218675 A (refer to claims 1 and 2, paragraphs [0019], [0020], [0026], etc.)
  • JP 2008-277672 A (refer to claims 1, 5, 6 and paragraphs [0039], [0062], [0063], [0068] to [0072], etc.)
  • the present invention has been made to solve the above-described problems, and its object is to efficiently generate non-180 ° domain rotation and obtain high piezoelectric characteristics without using a special substrate.
  • An object of the present invention is to provide a ferroelectric film that can be easily applied to MEMS and a piezoelectric element including the ferroelectric film.
  • a ferroelectric film according to one aspect of the present invention is a ferroelectric film made of a perovskite crystal, the crystal orientation is ⁇ 100> main orientation, rhombohedral and tetragonal crystals are mixed, and the tetragonal crystal In FIG.
  • a-axis orientation and c-axis orientation are mixed, and function F indicating ⁇ 100> peak by 2 ⁇ / ⁇ measurement of X-ray diffraction is expressed as tetragonal crystal with a-axis orientation, tetragonal crystal with c-axis orientation, rhomboid
  • the ratio of the integral values of F3 is 0.2 or more and 0.8 or less.
  • (A)-(c) is sectional drawing which shows the film-forming process of the PZT film
  • FIG. 7 is a cross-sectional view taken along line A-A ′ of FIG. 6. It is explanatory drawing which shows typically the crystal structure of PZT.
  • A) is explanatory drawing which shows the polarization direction of a tetragonal crystal
  • (b) is explanatory drawing which shows the polarization direction of a rhombohedral crystal. It is explanatory drawing which shows each piezoelectric distortion at the time of applying an electric field to a c-axis direction with respect to the tetragonal c-axis orientation domain and a-axis orientation domain.
  • FIG. 1A to FIG. 1C are cross-sectional views showing a process of forming a PZT film as a ferroelectric film of this example.
  • a thermal oxide film 2 made of, for example, SiO 2 having a thickness of about 100 nm is formed on a substrate 1 made of a single crystal Si wafer having a thickness of about 400 ⁇ m.
  • the substrate 1 may be a standard substrate having a thickness of 300 ⁇ m to 725 ⁇ m and a diameter of 3 inches to 8 inches.
  • the thermal oxide film 2 can be formed by exposing the substrate 1 to a high temperature of about 1200 ° C. in an oxygen atmosphere using a wet oxidation furnace.
  • an adhesion layer made of Ti having a thickness of about 20 nm and a Pt electrode layer having a thickness of about 100 nm are sequentially formed on the thermal oxide film 2.
  • the adhesion layer and the Pt electrode layer are collectively referred to as a lower electrode 3.
  • Ti and Pt are formed by sputtering, for example.
  • the sputtering conditions for Ti at this time were Ar flow rate: 20 sccm, pressure: 0.4 Pa, RF power applied to the target: 200 W, and the sputtering conditions for Pt were Ar flow rate: 20 sccm, pressure: 0.4 Pa, on the target Applied RF power: 150 W, substrate temperature: 530 ° C.
  • Pt becomes a film having ⁇ 111> orientation due to its self-orientation, it has a high crystallinity because it affects the quality of the PZT film formed on Pt.
  • the adhesion layer may be made of TiOx instead of Ti.
  • TiOx can also be formed by introducing reactive oxygen during Ti sputtering and forming a film by reactive sputtering, or heating at about 700 ° C. in an oxygen atmosphere in an RTA (Rapid Thermal Annealing) furnace after Ti film formation. It can also be formed by performing.
  • a PZT film 4 that is a ferroelectric film is formed on the substrate 1 with Pt by sputtering.
  • the formation method of the ferroelectric film is not limited to the sputtering method, but other physical film formation methods such as a pulse laser deposition (PLD) method and an ion plating method, and chemical film formation such as an MOCVD method and a sol-gel method. The law may be used.
  • a sputtering target having a Zr / Ti molar ratio of 52/48 having an MPB (Morphotropic Phase Boundary) composition was used.
  • Pb contained in the target is likely to be re-evaporated during high-temperature film formation, and the formed thin film tends to be Pb deficient. Therefore, it is desirable to add the Pb to the target in a larger amount than the stoichiometric ratio of the perovskite crystal.
  • the amount of Pb added is preferably 10 to 30% higher than the stoichiometric ratio, although it depends on the film formation temperature.
  • the PZT sputtering conditions were Ar flow rate: 25 sccm, O 2 flow rate: 0.4 sccm, pressure: 0.4 Pa, substrate temperature: 500 ° C., RF power: 500 W, and a PZT film 4 having a thickness of 5 ⁇ m was formed.
  • a PZT film 4 having an average particle diameter of 1 ⁇ m could be formed.
  • FIG. 2 shows the result of 2RD / ⁇ measurement of XRD (X-ray diffraction) for the PZT film 4 of Example 1.
  • intensity (diffraction intensity, reflection intensity) of the vertical axis
  • the crystal orientation of the PZT film 4 is the ⁇ 100> main orientation. I can say that.
  • the main orientation means that the orientation rate F measured by the Lotgering method is 80% or more and has crystal orientation.
  • the orientation rate F at this time is represented by the following formula.
  • F (%) (P ⁇ P 0 ) / (1 ⁇ P 0 ) ⁇ 100
  • P refers to the ratio of the total reflection intensity from the orientation plane to the total reflection intensity.
  • P I ⁇ 100> / [I ⁇ 100> + I ⁇ 110> + I ⁇ 111>]
  • P 0 P of the non-oriented sample.
  • F 0%
  • F 100%.
  • the orientation rate F was 100%.
  • the crystal orientation direction of the PZT film 4 is random, piezoelectric distortion may be canceled between adjacent crystals when a voltage is applied.
  • the crystal orientation of the PZT film 4 is the ⁇ 100> main orientation, and the crystal orientation directions are aligned in almost one direction, so that the piezoelectric strain is canceled between adjacent crystals when a voltage is applied. Can be suppressed, and the piezoelectric characteristics can be improved.
  • FIG. 3 shows that for the ⁇ 100> diffraction intensity peak (hereinafter referred to as ⁇ 100> peak) of the PZT film 4 by 2 ⁇ / ⁇ measurement of X-ray diffraction, fitting with a forked function is performed using dedicated software.
  • the results are shown in which the function F indicating the ⁇ 100> peak is divided into a plurality of functions F1, F2 and F3.
  • the functions F1, F2 and F3 are functions indicating the diffraction intensity of X-rays incident on the a-axis oriented tetragonal crystal, the c-axis oriented tetragonal crystal and the rhombohedral crystal, respectively.
  • the vertical axis of the graph showing the functions F1, F2 and F3 indicates the relative intensity of the function F with respect to the maximum intensity.
  • 2 ⁇ / ⁇ measurement of X-ray diffraction means that X-rays are incident on the sample at an angle ⁇ from the horizontal direction (at an angle ⁇ relative to the crystal plane) and reflected from the sample.
  • This is a technique for investigating an intensity change with respect to ⁇ by detecting X-rays having an angle of 2 ⁇ with respect to incident X-rays.
  • the surface spacing lace constant
  • the lattice constant in the a-axis direction is 4.04 angstroms
  • the lattice constant in the c-axis direction is 4.14 angstroms
  • the lattice constant of rhombohedral crystals is 4.07 angstroms. Therefore, the values of 2 ⁇ corresponding to the crystal structures are different from each other. Therefore, based on the 2 ⁇ value at which the diffraction intensity increases, it is determined whether the crystal structure of the sample on which the X-rays are incident is an a-axis oriented tetragonal crystal, a c-axis oriented tetragonal crystal, or a rhombohedral crystal. be able to.
  • FIG. 4 shows the integrated values (areas) of the functions F1, F2 and F3, respectively.
  • the sum of the integrated values of the three functions F1, F2 and F3 corresponding to the crystal structures of the a-axis oriented tetragonal crystal, the c-axis oriented tetragonal crystal and the rhombohedral crystal is 1.
  • the PZT film 4 includes both tetragonal crystals and rhombohedral crystals, and in the tetragonal crystals, a-axis orientation and c-axis orientation are mixed.
  • a 90 ° domain rotation from the a-axis direction to the c-axis direction, ie, non- A 180 [deg.] Domain rotation can be generated to produce a strain greater than the normal piezoelectric strain due to the c-axis oriented domain.
  • the lattice constant of Si used as the material of the substrate 1 is about 5.4 angstroms, which is much larger than the lattice constant of PZT described above, so it is clear that the PZT film 4 is not an epitaxial film. It is. Therefore, rhombohedral crystals and tetragonal crystals can be mixed in the PZT film 4, and the above-described effects can be obtained.
  • FIG. 5 shows a schematic configuration of the piezoelectric displacement meter.
  • the end of the piezoelectric element 10 is clamped with a fixed portion 11 so that the movable length of the cantilever is 10 mm, and a cantilever structure is formed.
  • a voltage of 0 V and a minimum voltage of ⁇ 20 V was applied to the lower electrode 3 at a frequency of 500 Hz, and the displacement of the end of the piezoelectric element 10 was observed with a laser Doppler vibrometer 13.
  • the piezoelectric displacement of the piezoelectric element 10 was 2.2 ⁇ m. From this piezoelectric displacement, the piezoelectric constant d 31 can be calculated using the following calculation formula disclosed in Non-Patent Document 1.
  • h s is the substrate thickness
  • s p elastic compliance of the thin film PZT is the elastic compliance of the substrate
  • L is the length of the cantilever
  • V is the applied voltage
  • Comparative piezoelectric constant d 31 since sufficient in comparison of the absolute value, in the following, demonstrate the value of piezoelectric constant d 31 in absolute value.
  • FIG. 4 also shows the value (absolute value) of the piezoelectric constant d 31 in this example.
  • Example 2 In this example, the PZT film 4 was formed on the wafer manufactured up to the lower electrode 3 as in Example 1 using the same target as in Example 1. However, among the sputtering conditions for the PZT film 4, only the O 2 flow rate was changed to 0.8 sccm, and the other conditions were the same as in Example 1 to form the PZT film 4. Thereafter, as in Example 1, the upper electrode 5 was formed on the PZT film 4 to complete the piezoelectric element 10.
  • FIG. 4 shows the results of crystal structure evaluation and piezoelectric displacement measurement by XRD for the formed PZT film 4 and piezoelectric element 10 as in Example 1. From the figure, it was found that in the PZT film 4 of this example, as in Example 1, a-axis oriented tetragonal crystals, c-axis oriented tetragonal crystals, and rhombohedral crystals were mixed. The piezoelectric constant d 31 was slightly lower than that in Example 1, but a relatively good value of 150 [pm / V].
  • Example 3 the PZT film 4 was formed by sputtering using the same target as in Example 1 on the wafer manufactured up to the lower electrode 3 as in Example 1.
  • the sputtering conditions at this time are Ar flow rate: 30 sccm, O 2 flow rate: 0.5 sccm, pressure: 0.9 Pa, substrate temperature: 550 ° C., RF power: 500 W.
  • the upper electrode 5 was formed on the PZT film 4 to complete the piezoelectric element 10.
  • FIG. 4 shows the results of crystal structure evaluation and piezoelectric displacement measurement by XRD for the formed PZT film 4 and piezoelectric element 10 as in Example 1.
  • the piezoelectric constant d 31 was slightly lower than that in Example 1, but was 153 [pm / V], which was a relatively good value similar to that in Example 2.
  • a PZT film 4 is formed under the same sputtering conditions as in Example 1, using a target having a Ti ratio that is several percent higher than that in Example 1 on the wafer manufactured up to the lower electrode 3 as in Example 1. Formed. By using such a target, it is possible to form the PZT film 4 in which the proportion of rhombohedral crystals is reduced. Thereafter, as in Example 1, the upper electrode 5 was formed on the PZT film 4 to complete the piezoelectric element 10.
  • FIG. 4 shows the results of crystal structure evaluation and piezoelectric displacement measurement by XRD for the formed PZT film 4 and piezoelectric element 10 as in Example 1.
  • the piezoelectric constant d 31 in this comparative example is 115 [pm / V], which is considerably lower than that in the first embodiment. This is because, compared with Example 1, the proportion of rhombohedral crystals contained in the PZT film 4 decreased, and the proportion of tetragonal crystals with c-axis orientation increased, so that the composition ratio deviated from the MPB composition. This is thought to be due to the fact that the domain rotation of ° does not occur efficiently.
  • Comparative Example 2 In this comparative example, the PZT film 4 was formed on the wafer manufactured up to the lower electrode 3 in the same manner as in Example 1, using the same target as in Comparative Example 1 and under the same sputtering conditions as in Example 2. Thereafter, as in Example 1, the upper electrode 5 was formed on the PZT film 4 to complete the piezoelectric element 10.
  • FIG. 4 shows the results of crystal structure evaluation and piezoelectric displacement measurement by XRD for the formed PZT film 4 and piezoelectric element 10 as in Example 1.
  • the piezoelectric constant d 31 in this comparative example was 100 [pm / V], which was even lower than that in Comparative example 1.
  • the ratio of a-axis-oriented tetragonal crystals contained in the PZT film 4 is decreased, and the ratio of c-axis-oriented tetragonal crystals is increased. This is thought to be due to an increase in the rate of piezoelectric strain and a decrease in the rate of piezoelectric strain using non-180 ° domain rotation from the a-axis direction to the c-axis direction.
  • a PZT film 4 is formed under the same sputtering conditions as in Example 1 using a target having a Zr ratio that is several percent higher than that in Example 1 on the wafer manufactured up to the lower electrode 3 as in Example 1. Formed. By using such a target, the PZT film 4 having an increased rhombohedral ratio can be formed. Thereafter, as in Example 1, the upper electrode 5 was formed on the PZT film 4 to complete the piezoelectric element 10.
  • FIG. 4 shows the results of crystal structure evaluation and piezoelectric displacement measurement by XRD for the formed PZT film 4 and piezoelectric element 10 as in Example 1.
  • the piezoelectric constant d 31 in this comparative example is 130 [pm / V], which is lower than that in Example 2. This is because when the proportion of rhombohedral crystals contained in the PZT film 4 increases too much, the a-axis orientation and the c-axis orientation are not mixed in the tetragonal crystal, and the effect of non-180 ° domain rotation cannot be obtained. It is considered that the piezoelectric characteristics are deteriorated.
  • the ratio of the integral value of the function F1 corresponding to the tetragonal crystal with the a-axis orientation to the sum of the integral values of the three functions F1, F2, and F3 is 0.4 or more and 0.00. It can be said that it is desirable to be 5 or less.
  • FIG. 6 is a plan view showing a configuration when the PZT film 4 of Examples 1 and 2 is applied to a diaphragm (diaphragm) as a piezoelectric element 10 ′ manufactured using the MEMS technology
  • FIG. FIG. 7 is a cross-sectional view taken along line AA ′ in FIG.
  • the piezoelectric element 10 ′ is configured by laminating a thermal oxide film 2, a lower electrode 3, a PZT film 4 as a ferroelectric film, and an upper electrode 5 in this order on a substrate 1.
  • the PZT film 4 is disposed in a necessary area of the substrate 1 in a two-dimensional staggered pattern.
  • a region corresponding to the formation region of the PZT film 4 in the substrate 1 is a recess 1a in which a part in the thickness direction is removed with a circular cross section, and the upper portion of the recess 1a in the substrate 1 (the bottom side of the recess 1a). ) Remains a thin plate-like region 1b.
  • the lower electrode 3 and the upper electrode 5 are connected to an external control circuit by wiring not shown.
  • the predetermined PZT film 4 By applying an electrical signal from the control circuit to the lower electrode 3 and the upper electrode 5 sandwiching the predetermined PZT film 4, only the predetermined PZT film 4 can be driven. That is, when a predetermined electric field is applied to the upper and lower electrodes of the PZT film 4, the PZT film 4 expands and contracts in the left-right direction, and the PZT film 4 and the region 1b of the substrate 1 are bent up and down by the bimetal effect. Therefore, when the recess 1a of the substrate 1 is filled with gas or liquid, the piezoelectric element 1 can be used as a pump, which is suitable for an inkjet head, for example.
  • the deformation amount of the PZT film 4 can be detected by detecting the charge amount of the predetermined PZT film 4 through the lower electrode 3 and the upper electrode 5. That is, when the PZT film 4 is vibrated by sound waves or ultrasonic waves, an electric field is generated between the upper and lower electrodes due to an effect opposite to that described above. By detecting the magnitude of the electric field and the frequency of the detection signal at this time, The element 1 can also be used as a sensor (ultrasonic sensor). Furthermore, since the PZT film 4 exhibits a pyroelectric effect, the piezoelectric element 1 can be used as a pyroelectric sensor (infrared sensor).
  • the piezoelectric element 1 can also be used as a frequency filter (surface acoustic wave filter) by using the piezoelectric effect of the PZT film 4, and the piezoelectric element 1 can be made non-volatile by using the PZT film 4 as a ferroelectric substance. It can also be used as a memory.
  • PZT has been described as an example of the constituent material of the ferroelectric film.
  • PZT is also expressed as Pb (Zr, Ti) O 3
  • Pb ions are included at the A site
  • Zr ions and Ti ions are present at the B site.
  • a lead-based metal oxide see FIG. 8).
  • Such a lead-based metal oxide exhibits a good piezoelectric characteristic by adopting a perovskite structure, and is therefore suitable for the ferroelectric film of the above-described embodiment.
  • an additive may be contained in at least one of the A site and the B site of PZT.
  • a lanthanoid metal containing Nd or La, or a metal ion of at least one of Sr and Bi can be considered.
  • the metal ion of at least any one of Nb, Ta, W, and Sb can be considered, for example.
  • ferroelectric film in which such an additive is added to PZT for example, PLZT ((Pb, La) (Zr, Ti) O 3 ), PSZT ((Pb, Sr) (Zr, Ti) O 3 ) , PNZT (Pb (Zr, Ti, Nb) O 3 ).
  • a metal oxide obtained by adding an additive to PZT exhibits a good piezoelectric characteristic by adopting a perovskite structure, and thus is suitable for the ferroelectric film of the above-described embodiment.
  • the ferroelectric film may be made of a lead-free metal oxide as long as it has a perovskite structure.
  • a lead-free metal oxide when the perovskite crystal is represented by the general formula ABO 3 , the A site contains at least one of Sr, Ba, and Bi metal ions, and the B site contains Ti ions or The thing containing Ta ion can be considered. Specifically, BST ((Ba, Sr) TiO 3 ) or SBT (SrBi 2 Ta 2 O 9 ) can be considered.
  • lead-free metal oxides such as BST and SBT exhibit a good piezoelectric characteristic by adopting a perovskite structure, they are suitable for a ferroelectric film of a piezoelectric element.
  • the ferroelectric film described above is a ferroelectric film made of a perovskite crystal, in which the crystal orientation is ⁇ 100> main orientation and rhombohedral and tetragonal crystals are mixed.
  • Axial orientation and c-axis orientation coexist, and the function F indicating the ⁇ 100> peak by 2 ⁇ / ⁇ measurement of X-ray diffraction is expressed as a tetragonal crystal with an a-axis orientation, a tetragonal crystal with a c-axis orientation, and a rhombohedral crystal.
  • the value ratio is 0.2 or more and 0.8 or less.
  • the crystal orientation is the ⁇ 100> main orientation and the crystal orientation directions are substantially aligned in one direction, piezoelectric distortion (piezoelectric displacement) is canceled between adjacent crystals when a voltage is applied. Can be suppressed.
  • the a-axis orientation and the c-axis orientation are mixed in the tetragonal crystal, a 90 ° domain rotation from the a-axis direction to the c-axis direction, that is, a non-180 ° domain rotation is caused.
  • a strain larger than the normal piezoelectric strain due to the axially oriented domain can be generated.
  • the function F indicating the ⁇ 100> peak by 2 ⁇ / ⁇ measurement of X-ray diffraction indicates the diffraction intensity of X-rays incident on each of an a-axis oriented tetragonal crystal, a c-axis oriented tetragonal crystal, and a rhombohedral crystal.
  • the ratio of the integral value of the function F3 corresponding to the rhombohedral crystal to the sum of the integral values of the three functions F1 to F3 is 0.2 or more and 0.8 or less.
  • a thin film such as a ferroelectric film can efficiently generate non-180 ° domain rotation and obtain high piezoelectric characteristics.
  • a special substrate a substrate whose surface crystal plane is inclined
  • the ratio is 0.4 or more and 0.5 or less, higher piezoelectric characteristics can be obtained with certainty.
  • the ferroelectric film described above is a lead-based metal oxide containing Pb ions at the A site and Zr ions and Ti ions at the B site when the perovskite crystal is represented by the general formula ABO 3 . Can be configured.
  • lead-based metal oxides such as PZT exhibit a good piezoelectric characteristic by adopting a perovskite structure, they are suitable for the ferroelectric film.
  • the metal oxide includes an additive at at least one of the A site and the B site, and the additive at the A site is at least one of a lanthanoid metal, Sr, and Bi. It is a metal ion, and the additive at the B site may be a metal ion of at least one of Nb, Ta, W, and Sb.
  • a metal oxide obtained by adding an additive to PZT is suitable for the ferroelectric film because it exhibits good piezoelectric characteristics by adopting a perovskite structure.
  • the ferroelectric film contains at least one of Sr, Ba, and Bi metal ions at the A site, and Ti ions or Ta ions at the B site. It may be composed of a lead-free metal oxide.
  • Lead-free metal oxides such as BST (barium strontium titanate) and SBT (strontium bismuth tantalate) exhibit good piezoelectric properties by adopting a perovskite structure, and are therefore suitable for the ferroelectric film. .
  • the piezoelectric element described above is a piezoelectric element in which a lower electrode, a ferroelectric film, and an upper electrode are laminated in this order on a substrate, and the ferroelectric film is composed of the ferroelectric film described above. Has been.
  • the above-described ferroelectric film does not require a special substrate to cause non-180 ° domain rotation, and can be easily applied to MEMS. Therefore, the ferroelectric film is high in a piezoelectric element manufactured using MEMS technology. Piezoelectric characteristics can be easily realized.
  • a thin film such as a ferroelectric film can efficiently cause non-180 ° domain rotation and obtain high piezoelectric characteristics.
  • the ferroelectric film can be easily applied to MEMS.
  • the present invention can be used in, for example, MEMS actuators (inkjet printers and projector actuators), MEMS sensors (pyroelectric sensors, ultrasonic sensors), frequency filters, and nonvolatile memories.
  • MEMS actuators injet printers and projector actuators
  • MEMS sensors pyroelectric sensors, ultrasonic sensors
  • frequency filters frequency filters
  • nonvolatile memories nonvolatile memories

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

Un film ferroélectrique est produit à partir de cristaux de pérovskite. L'orientation cristalline est une orientation principale <100> et des cristaux rhomboédriques et des cristaux tétragonaux sont mélangés. Parmi les cristaux tétragonaux, une orientation suivant l'axe a et une orientation suivant l'axe c sont mélangées. Si une fonction (F) indiquant un pic <100> dans la mesure 2θ/θ<span lang=FR style='font-family:"Courier New"'> de la diffraction X est divisée en fonctions (F1, F2, F3) indiquant les intensités de diffraction des rayons X frappant les cristaux tétragonaux dans l'orientation suivant l'axe a, les cristaux tétragonaux dans l'orientation suivant l'axe c et les cristaux tétraédriques, respectivement</span>, le rapport entre la valeur entière de la fonction (F3) correspondant aux cristaux rhomboédriques et le total des valeurs entières des trois fonctions (F1, F2, F3) s'étend de 0,2 à 0,8 (inclusivement).
PCT/JP2012/061854 2011-05-31 2012-05-09 Film ferroélectrique et élément piézoélectrique le comprenant WO2012165110A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2011-122208 2011-05-31
JP2011122208 2011-05-31

Publications (1)

Publication Number Publication Date
WO2012165110A1 true WO2012165110A1 (fr) 2012-12-06

Family

ID=47258974

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2012/061854 WO2012165110A1 (fr) 2011-05-31 2012-05-09 Film ferroélectrique et élément piézoélectrique le comprenant

Country Status (1)

Country Link
WO (1) WO2012165110A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014199910A (ja) * 2013-03-14 2014-10-23 株式会社リコー 圧電体薄膜素子及びインクジェット記録ヘッド、並びにインクジェット式画像形成装置
JP2015038956A (ja) * 2013-03-29 2015-02-26 三菱マテリアル株式会社 Ｐｚｔ系強誘電体薄膜及びその形成方法
WO2015064341A1 (fr) * 2013-10-29 2015-05-07 コニカミノルタ株式会社 Élément piézoélectrique, tête à jet d'encre, imprimante à jet d'encre et procédé de production d'élément piézoélectrique
WO2016031134A1 (fr) * 2014-08-29 2016-03-03 富士フイルム株式会社 Film piézoélectrique, son procédé de fabrication, élément piézoélectrique et dispositif de décharge de liquide
CN111344876A (zh) * 2017-11-13 2020-06-26 前进材料科技株式会社 膜结构体及其制造方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007029850A1 (fr) * 2005-09-05 2007-03-15 Canon Kabushiki Kaisha Film d’oxyde épitaxial, film piézoélectrique, élément de film piézoélectrique, et tête de distribution de liquide et dispositif de distribution de liquide utilisant l’élément de film piézoélectrique
JP2008094707A (ja) * 2006-09-15 2008-04-24 Fujifilm Corp ペロブスカイト型酸化物とその製造方法、圧電体、圧電素子、液体吐出装置
JP2008218675A (ja) * 2007-03-02 2008-09-18 Canon Inc 圧電体、圧電体素子、圧電体素子を用いた液体吐出ヘッド及び液体吐出装置
JP2008306164A (ja) * 2007-04-26 2008-12-18 Fujifilm Corp 圧電体、圧電素子、及び液体吐出装置
JP2010080813A (ja) * 2008-09-29 2010-04-08 Fujifilm Corp 圧電体膜とその製造方法、圧電素子、及び液体吐出装置
JP2010182717A (ja) * 2009-02-03 2010-08-19 Fujifilm Corp 圧電体とその製造方法、圧電素子、及び液体吐出装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007029850A1 (fr) * 2005-09-05 2007-03-15 Canon Kabushiki Kaisha Film d’oxyde épitaxial, film piézoélectrique, élément de film piézoélectrique, et tête de distribution de liquide et dispositif de distribution de liquide utilisant l’élément de film piézoélectrique
JP2008094707A (ja) * 2006-09-15 2008-04-24 Fujifilm Corp ペロブスカイト型酸化物とその製造方法、圧電体、圧電素子、液体吐出装置
JP2008218675A (ja) * 2007-03-02 2008-09-18 Canon Inc 圧電体、圧電体素子、圧電体素子を用いた液体吐出ヘッド及び液体吐出装置
JP2008306164A (ja) * 2007-04-26 2008-12-18 Fujifilm Corp 圧電体、圧電素子、及び液体吐出装置
JP2010080813A (ja) * 2008-09-29 2010-04-08 Fujifilm Corp 圧電体膜とその製造方法、圧電素子、及び液体吐出装置
JP2010182717A (ja) * 2009-02-03 2010-08-19 Fujifilm Corp 圧電体とその製造方法、圧電素子、及び液体吐出装置

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014199910A (ja) * 2013-03-14 2014-10-23 株式会社リコー 圧電体薄膜素子及びインクジェット記録ヘッド、並びにインクジェット式画像形成装置
US9586401B2 (en) 2013-03-14 2017-03-07 Ricoh Company, Ltd. Piezoelectric thin film element, inkjet recording head, and inkjet image-forming apparatus
JP2015038956A (ja) * 2013-03-29 2015-02-26 三菱マテリアル株式会社 Ｐｚｔ系強誘電体薄膜及びその形成方法
US9251955B2 (en) 2013-03-29 2016-02-02 Mitsubishi Materials Corporation PZT-based ferroelectric thin film and method of forming the same
WO2015064341A1 (fr) * 2013-10-29 2015-05-07 コニカミノルタ株式会社 Élément piézoélectrique, tête à jet d'encre, imprimante à jet d'encre et procédé de production d'élément piézoélectrique
JPWO2015064341A1 (ja) * 2013-10-29 2017-03-09 コニカミノルタ株式会社 圧電素子、インクジェットヘッド、インクジェットプリンタおよび圧電素子の製造方法
US9889652B2 (en) 2013-10-29 2018-02-13 Konica Minolta, Inc. Piezoelectric device, inkjet head, inkjet printer, and method of manufacturing piezoelectric device
WO2016031134A1 (fr) * 2014-08-29 2016-03-03 富士フイルム株式会社 Film piézoélectrique, son procédé de fabrication, élément piézoélectrique et dispositif de décharge de liquide
JPWO2016031134A1 (ja) * 2014-08-29 2017-06-15 富士フイルム株式会社 圧電体膜とその製造方法、圧電素子、及び液体吐出装置
US10011111B2 (en) 2014-08-29 2018-07-03 Fujifilm Corporation Piezoelectric film, production method thereof, piezoelectric element, and liquid discharge apparatus
CN111344876A (zh) * 2017-11-13 2020-06-26 前进材料科技株式会社 膜结构体及其制造方法
CN111344876B (zh) * 2017-11-13 2023-10-17 日商爱伯压电对策股份有限公司 膜结构体及其制造方法

Similar Documents

Publication Publication Date Title
JP5525143B2 (ja) 圧電薄膜素子及び圧電薄膜デバイス
JP5817926B2 (ja) 圧電素子
JP5311787B2 (ja) 圧電素子及び液体吐出ヘッド
JP5599203B2 (ja) 圧電薄膜、圧電素子、圧電素子の製造方法、液体吐出ヘッドおよび超音波モータ
WO2012005032A1 (fr) Elément à film piézoélectrique et dispositif à film piézoélectrique
JP5808262B2 (ja) 圧電体素子及び圧電体デバイス
JP6547418B2 (ja) 圧電素子、圧電アクチュエータ、圧電センサ、ハードディスクドライブ、及びインクジェットプリンタ装置
JP5790759B2 (ja) 強誘電体薄膜およびその製造方法
JP2010238856A (ja) 圧電体素子及びジャイロセンサ
JP5472549B1 (ja) 圧電素子、圧電デバイス、インクジェットヘッドおよびインクジェットプリンタ
WO2012165110A1 (fr) Film ferroélectrique et élément piézoélectrique le comprenant
US9620703B2 (en) Piezoelectric thin-film element, piezoelectric sensor and vibration generator
Shimizu et al. Large Piezoelectric Response in Lead-Free (Bi0. 5Na0. 5) TiO3-Based Perovskite Thin Films by Ferroelastic Domain Switching: Beyond the Morphotropic Phase Boundary Paradigm
JP6478023B2 (ja) 圧電素子、圧電アクチュエーター装置、液体噴射ヘッド、液体噴射装置及び超音波測定装置
JP4998652B2 (ja) 強誘電体薄膜、強誘電体薄膜の製造方法、圧電体素子の製造方法
JP5103790B2 (ja) 圧電薄膜、圧電薄膜を用いた素子及び圧電薄膜素子の製造方法
JP5835460B2 (ja) 圧電薄膜、圧電素子、インクジェットヘッド、インクジェットプリンタおよび圧電薄膜の製造方法
JP2009049065A (ja) 圧電薄膜素子
Ishihama et al. Achieving High Piezoelectric Performance across a Wide Composition Range in Tetragonal (Bi, Na) TiO3–BaTiO3 Films for Micro-electromechanical Systems
Kanda et al. Characteristics of Sputtered Lead Zirconate Titanate Thin Films with Different Layer Configurations and Large Thickness
WO2023042704A1 (fr) Élément piézoélectrique, actionneur piézoélectrique, tête d&#39;évacuation de gouttelettes de liquide, dispositif d&#39;évacuation de gouttelettes de liquide et mémoire ferroélectrique
JP7067085B2 (ja) 圧電素子及び液体吐出ヘッド
SNOOK et al. TRANSDUCER MATERIALS
JP2007281338A (ja) 圧電素子および圧電材料

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12793570

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12793570

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP