JP4507565B2 - Piezoelectric device manufacturing method, liquid discharge head manufacturing method, and droplet discharge apparatus manufacturing method - Google Patents

Description

  The present invention relates to a piezoelectric device or a ferroelectric device including a piezoelectric film or a ferroelectric film and a pair of electrodes disposed therebetween, a ferroelectric device, a liquid discharge head including these devices, and an electronic apparatus. The present invention relates to a piezoelectric device having a piezoelectric film or a ferroelectric film having excellent orientation.

As a piezoelectric film or a ferroelectric film used for a piezoelectric device or a ferroelectric device, a composite oxide having a perovskite crystal structure and represented by a chemical formula ABO ₃ is known. For example, lead zirconate titanate (PZT) in which lead (Pb) is applied to A and a mixture of zirconium (Zr) and titanium (Ti) is applied to B is known.

  In order to improve the characteristics of the piezoelectric film or the ferroelectric film, various attempts have been made to align the crystal orientation in a desired direction. In particular, it is desired to obtain an in-plane oriented piezoelectric film or ferroelectric film in which orientation directions are aligned in all three-dimensional directions.

In the field of oxide superconductors, formation of an in-plane alignment film by an ion beam assist method has been proposed (Japanese Patent Laid-Open No. 6-145977).
JP-A-6-145977

  However, it has been difficult to efficiently obtain an in-plane oriented piezoelectric film or ferroelectric film.

  An object of the present invention is to provide a method for efficiently producing a piezoelectric device or a ferroelectric device provided with an in-plane oriented piezoelectric film or a ferroelectric film.

  In the method of manufacturing a piezoelectric device according to the present invention, a lower electrode is formed on a substrate, a piezoelectric film is formed on the lower electrode by an ion beam assist method, and an upper electrode is formed on the piezoelectric film. It is characterized by.

  In the above manufacturing method, the piezoelectric film is preferably formed of PZT, BST, or a relaxor material.

In particular, the piezoelectric film is made of Pb (M _1/3 N _2/3 ) O ₃ (M = Mg, Zn, Co, Ni, Mn, N = Nb, Ta), Pb (M _1/2 N _{1 / 2} ) O ₃ (M = Sc, Fe, In, Yb, Ho, Lu, N = Nb, Ta), Pb (M _1/2 N _1/2 ) O ₃ (M = Mg, Cd, Mn, Co, N = W, Re), Pb (M _2/3 N _1/3 ) O ₃ (M = Mn, Fe, N = W, Re), or a relaxor material PMN composed of a mixed phase and Pb (Zr _x Including solid solution PMN _y -PZT _1-y with Ti _1-x ) O ₃ (PZT, 0.0 ≦ x ≦ 1.0), and cubic (100), tetragonal (001), rhombohedral ( 100) and pseudo-cubic crystal (100).

  According to another aspect of the invention, there is provided a method for manufacturing a liquid discharge head, comprising: forming a piezoelectric device by the manufacturing method described above; and a cavity whose internal volume changes due to deformation of the piezoelectric film of the piezoelectric device. Forming on the substrate.

  The manufacturing method of the liquid discharge apparatus of the present invention is characterized by using the liquid discharge head formed by the above manufacturing method.

  In the method of manufacturing a ferroelectric device according to the present invention, a lower electrode is formed on a substrate, a ferroelectric film is formed on the lower electrode by an ion beam assist method, and an upper electrode is formed on the ferroelectric film. It is characterized by forming.

The ferroelectric film is made of Pb (M _1/3 N _2/3 ) O ₃ (M = Mg, Zn, Co, Ni, Mn, N = Nb, Ta), Pb (M _1/2 N _1/2 ) O ₃ (M = Sc, Fe, In, Yb, Ho, Lu, N = Nb, Ta), Pb (M _1/2 N _1/2 ) O ₃ (M = Mg, Cd, Mn, Co, N = W, Re), Pb (M _2/3 N _1/3 ) O ₃ (M = Mn, Fe, N = W, Re), or a relaxor material PMN composed of a mixed phase and Pb (Zr _x Ti _1-x ) O ₃ (PZT, 0.0 ≦ x ≦ 1.0) and solid solution PMN _y —PZT _1-y , and cubic (100), tetragonal (001), rhombohedral (100 ) And pseudo cubic (100).

  The method for manufacturing a ferroelectric memory according to the present invention electrically connects a step of forming a ferroelectric device by the above manufacturing method and a drive circuit for selectively applying a signal voltage to the ferroelectric device. And a step of performing.

  The electronic device manufacturing method of the present invention is characterized by using a ferroelectric device formed by the above manufacturing method.

  The piezoelectric device of the present invention is a piezoelectric device in which a lower electrode, a piezoelectric film and an upper electrode are formed on a substrate, and the piezoelectric film is in-plane orientation formed by an ion beam assist method. It is characterized by being a film.

  A liquid discharge head according to the present invention is a liquid discharge head including the above-described piezoelectric device, wherein a cavity whose internal volume changes due to deformation of the piezoelectric film is formed on the substrate.

  A liquid discharge apparatus according to the present invention includes the above-described liquid discharge head.

  The ferroelectric device of the present invention is a ferroelectric device in which a lower electrode, a ferroelectric film and an upper electrode are formed on a substrate, and the ferroelectric film is formed by an ion beam assist method. It is characterized by being an in-plane oriented film.

  A ferroelectric memory according to the present invention includes a ferroelectric device manufactured by the above manufacturing method, and a drive circuit that is electrically connected to the ferroelectric device and selectively applies a signal voltage. I have.

  An electronic apparatus according to the present invention includes a ferroelectric device formed by the above manufacturing method.

<1. Configuration of Ferroelectric Device>
FIG. 1 is a cross-sectional view of a capacitor which is a ferroelectric device of the present invention.

  The capacitor 200 shown in FIG. 1 is provided on the substrate 11, the lower electrode 13 formed on the substrate 11, the ferroelectric film 24 provided in a predetermined region thereon, and the ferroelectric film 24. And an upper electrode 25.

<1-1. Substrate>
The board | substrate 11 has a function which supports the lower electrode 13 grade | etc., And is comprised with the member which makes | forms flat form. An amorphous layer 15 is formed on the surface of the substrate 11 (upper side in FIG. 1). The amorphous layer 15 is a portion composed of a substance in an amorphous state, and may be either formed integrally with the substrate 11 or fixed to the substrate 11.

As the substrate 11, for example, a Si substrate, an SOI (Si on Insulator) substrate, or the like can be used. In this case, a film whose surface is covered with a SiO ₂ film that is a natural oxide film or a thermal oxide film can be used. That is, in this case, these natural oxide films or thermal oxide films constitute the amorphous layer 15.

Further, the amorphous layer 15 can be composed of various metal materials such as silicon nitride, silicon nitride oxide, zirconium oxide, etc. in addition to SiO ₂ . For example, a two-layer structure of 1000 nm SiO ₂ and 400 nm ZrO ₂ is used.

  Such an amorphous layer 15 is formed by, for example, chemical vapor deposition (CVD) such as thermal CVD, plasma CVD, or laser CVD, physical vapor deposition (PVD) such as vacuum vapor deposition, sputtering, or ion plating, sputter flow, or Si substrate. It is formed by thermal oxidation of the surface.

  Further, the substrate 11 itself may be made of an amorphous material. In this case, as the substrate 11, for example, polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene , Polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylpentene-1), ionomer, acrylic resin, polymethyl methacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyethylene terephthalate (PE ), Polyesters such as polybutylene terephthalate (PBT) and polycyclohexane terephthalate (PCT), polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM), polyphenylene oxide, Modified polyphenylene oxide, polysulfone, polyether sulfone, polyphenylene sulfide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluorine resins, styrene, polyolefin, polyvinyl chloride, Various thermoplastics such as polyurethane, polyester, polyamide, polybutadiene, trans polyisoprene, fluoro rubber, chlorinated polyethylene, etc. Stomer, epoxy resin, phenolic resin, urea resin, melamine resin, unsaturated polyester, silicone resin, polyurethane, etc., or various resin materials such as copolymers, blends, polymer alloys, etc., or various glass materials. A substrate composed of, for example, can be used.

  These Si substrate, SOI substrate, various resin substrates, various glass substrates and the like are all general-purpose substrates. For this reason, the manufacturing cost of the ferroelectric device can be reduced by using these substrates as the substrate 11.

  Although the average thickness of the board | substrate 11 is not specifically limited, It is preferable that it is about 10 micrometers-1 mm, and it is more preferable that it is about 100-600 micrometers. By setting the average thickness of the substrate 11 within the above range, the ferroelectric device can be thinned (downsized) while securing sufficient strength.

<1-2. Lower electrode>
A lower electrode 13 is formed on the substrate 11.

  The composition of the lower electrode 13 is not particularly limited as long as it has conductivity. However, it is desirable that the composition is made of a metal material such as Pt or Ir. For example, the layer structure may be a layer structure including a layer containing Ir / a layer containing Pt / a layer containing Ir from the lowest layer, a layer containing Ir / a layer containing Pt, or a layer containing Pt / a layer containing Ir. But you can. Moreover, you may comprise only the layer containing Ir.

  In addition, an adhesion layer (not shown) made of a metal that adheres both layers, preferably titanium or chromium, may be provided between the lower electrode and the substrate. The adhesion layer is formed in order to improve the adhesion to the installation surface of the piezoelectric element, and may not be formed if the adhesion can be ensured. For example, the lower electrode is formed by a layer structure of 20 nm thick Ti / 20 nm thick Ir / 140 nm thick Pt.

  The composition of the lower electrode 13 may include a metal oxide having a perovskite structure. In this case, the main material is preferably a metal oxide having a perovskite structure.

Examples of the metal oxide having a perovskite structure include CaRuO ₃ , SrRuO ₃ , BaRuO ₃ , SrVO ₃ , (La, Sr) MnO ₃ , (La, Sr) CrO ₃ , (La, Sr) CoO ₃ , LaNiO _x. Or a solid solution containing these, and in particular, CaRuO ₃ , SrRuO ₃ , BaRuO ₃ , or at least one of the solid solutions containing these is preferable. These metal oxides having a perovskite structure are excellent in conductivity and chemical stability. For this reason, the lower electrode 13 can also be excellent in conductivity and chemical stability.

  Moreover, the average thickness of the lower electrode 13 is not particularly limited, but is preferably about 10 to 300 nm, and more preferably about 50 to 150 nm. Thereby, the lower electrode 13 can sufficiently exhibit the function as an electrode and can prevent the ferroelectric device from becoming large.

<1-3. Ferroelectric film>
On the lower electrode 13, a ferroelectric film 24 is formed in an in-plane orientation by an ion beam assist method.

  Thereby, in the capacitor 200, for example, remanent polarization increases and coercive electric field decreases. That is, the capacitor 200 has various characteristics improved. Therefore, when a ferroelectric memory is manufactured using such a capacitor 200, the ferroelectric memory can be made excellent in the squareness of the hysteresis curve.

  The ferroelectric film 24 can be composed of various ferroelectric materials, but preferably includes a ferroelectric material having a perovskite structure, and more preferably includes a ferroelectric material having a perovskite structure as a main material. preferable. Further, the ferroelectric material having a perovskite structure includes tetragonal (001) orientation, rhombohedral (100) orientation, epitaxial growth with cubic (100) orientation, and pseudocubic crystal. Any of those grown epitaxially with (100) orientation may be used, but those with tetragonal (001) orientation are particularly preferred. Thereby, the said effect improves more.

As the ferroelectric material having the perovskite structure, for example, Pb (Zr, Ti) O ₃ (PZT), (Pb, La) (Zr, Ti) O ₃ (PLZT), (Ba, Sr) TiO ₃ ( BST), BaTiO ₃ , KNbO ₃ , Pb (Zn, Nb) O ₃ (PZN), Pb (Mg, Nb) O ₃ (PMN), PbFeO ₃ , PbWO ₃ metal oxides such as SrBi ₂ Bi-layered compounds such as (Ta, Nb) ₂ O ₉ , (Bi, La) ₄ Ti ₃ O ₁₂ , or solid solutions containing these (PMN-PT, PZN-PT, etc.) can be mentioned. In particular, relaxant materials such as PZT, BST, PMN-PT, PZN-PT, etc. are preferred as those suitable and suitable for forming an in-plane alignment film by the ion beam assist method. There. Furthermore, Pb (M _1/3 N _2/3 ) O ₃ (M = Mg, Zn, Co, Ni, Mn, N = Nb, Ta), Pb (M _1/2 N _1/2 ) O ₃ (M = Sc, Fe, In, Yb , Ho, Lu, N = Nb, Ta), Pb (M 1/2 N 1/2) O 3 (M = Mg, Cd, Mn, Co, N = W, Re) , Pb (M _2/3 N _1/3 ) O ₃ (M = Mn, Fe, N = W, Re), or a relaxor material PMN composed of a mixed phase and Pb (Zr _x Ti _1-x ) O ₃ (PZT, 0.0 ≦ x ≦ 1.0) and solid solution PMN _y -PZT _1-y is preferably included. As a result, the capacitor 200 has particularly excellent various characteristics.

  The average thickness of the ferroelectric film 24 is not particularly limited, but is preferably about 50 to 300 nm, and more preferably about 100 to 200 nm. By setting the average thickness of the ferroelectric film 24 within the above range, it is possible to obtain a capacitor 200 that can suitably exhibit various characteristics while preventing an increase in size of the capacitor 200.

<1-4. Upper electrode>
On the ferroelectric film 24, an upper electrode 25 having a comb-like shape (or a band shape) is formed.

  As a constituent material of the upper electrode 25, for example, one or more of Pt, Ir, Au, Ag, Ru, or an alloy containing these can be used in combination.

  The average thickness of the upper electrode 25 is not particularly limited, but is preferably about 10 to 300 nm, and more preferably about 50 to 150 nm.

<2. Manufacturing Method of Ferroelectric Device>
Next, a manufacturing method of the capacitor 200 which is such a ferroelectric device will be described with reference to FIG.

  The manufacturing method of the capacitor 200 shown below includes a step of forming the lower electrode 13 on the amorphous layer 15 (lower electrode forming step) and a step of forming the ferroelectric film 24 on the lower electrode 13 (ferroelectric film formation). Step), a step of removing a part of the ferroelectric film 24 (lower electrode extraction step), and a step of forming the upper electrode 25 on the ferroelectric film 24 (upper electrode forming step). . Hereinafter, each process will be described sequentially.

  First, the substrate 11 having the amorphous layer 15 is prepared. As the substrate 11, a substrate having a uniform thickness and free from bending and scratches is preferably used. The method for forming the amorphous layer 15 is as described above.

[1A] Lower Electrode Formation Step First, the lower electrode 13 is formed on the amorphous layer 15. The method of forming the lower electrode 13 is not particularly limited, but can be formed by a known thin film forming method such as sputtering, CVD, MOCVD, or laser ablation.

[2A] Ferroelectric Film Formation Step Next, a ferroelectric film 24 is formed on the lower electrode 13. This can be done, for example, as follows.

  First, the substrate 11 on which the lower electrode 13 and the like are formed is loaded into a substrate holder and installed in a vacuum apparatus.

  In the vacuum apparatus, a target (ferroelectric film target) including the constituent elements of the ferroelectric film 24 as described above is arranged at a predetermined distance from the lower electrode 13 of the substrate 11 so as to be spaced apart from each other. Has been. As the target, a target having the same composition as that of the target ferroelectric film 24 or an approximate composition is preferably used.

  Next, for example, when the target is irradiated with laser light, atoms including oxygen atoms and metal atoms are knocked out of the target, and a plume is generated. In other words, this plume is irradiated toward the lower electrode 13. The plume comes into contact with the lower electrode 13.

  At substantially the same time, the surface of the lower electrode 13 is irradiated with an ion beam inclined at a predetermined angle. As a result, a ferroelectric film 24 having, for example, tetragonal (001) orientation and in-plane orientation is formed on the lower electrode 13.

  In addition, as a method of knocking out the atoms from the target, in addition to a method of irradiating the target surface with laser light, for example, a method of irradiating (injecting) argon gas (inert gas) plasma, electron beam or the like onto the target surface. It can also be used.

  Among these, as a method of knocking out the atoms from the target, a method of irradiating the target surface with laser light is particularly preferable. According to such a method, atoms can be easily and reliably knocked out of the target by using a vacuum device having a simple structure including an incident window for laser light.

The laser light is preferably pulsed light having a wavelength of about 150 to 300 nm and a pulse length of about 1 to 100 ns. Specifically, examples of the laser light include excimer lasers such as ArF excimer laser, KrF excimer laser, and XeCl excimer laser, YAG laser, YVO ₄ laser, and CO ₂ laser. Among these, ArF excimer laser or KrF excimer laser is particularly suitable as the laser light. Both the ArF excimer laser and the KrF excimer laser are easy to handle, and can eject atoms from the target more efficiently.

The energy density of the laser beam is preferably 0.5 J / cm ² or more, and more preferably ² J / cm ² or more.

  The temperature of the substrate 11 on which the lower electrode 13 is formed is preferably about 0 to 100 ° C, and more preferably about 30 to 70 ° C.

  The distance between the substrate 11 on which the lower electrode 13 is formed and the target is preferably 30 to 100 mm, and more preferably about 50 to 80 mm.

The pressure in the vacuum apparatus is preferably 133 × 10 ⁻¹ Pa (1 × 10 ⁻¹ Torr) or less, and more preferably 133 × 10 ⁻³ Pa (1 × 10 ⁻³ Torr) or less. Further, in this case, the atmosphere in the vacuum apparatus is preferably set so that the mixing ratio of the inert gas and oxygen is about 300: 1 to 10: 1 by volume ratio, and about 150: 1 to 50: 1. Is more preferable.

  If the conditions for forming the ferroelectric film 24 are within the above ranges, the ferroelectric film 24 can be formed efficiently.

  At this time, the average thickness of the ferroelectric film 24 can be adjusted to the above-described range by appropriately setting the irradiation time of the laser beam. The irradiation time of the laser light varies depending on the above conditions, but is usually preferably about 3 to 90 minutes, more preferably about 15 to 45 minutes.

  On the other hand, the ion beam applied to the surface of the lower electrode 13 is not particularly limited. For example, at least one ion of an inert gas such as argon, helium, neon, xenon, or krypton, or these ions can be used. Examples thereof include mixed ions of ions and oxygen ions.

  As an ion source for this ion beam, for example, a Kauffman ion source or the like is preferably used. By using this ion source, an ion beam can be generated relatively easily.

  The irradiation angle of the ion beam with respect to the normal direction of the surface of the lower electrode 13 (the predetermined angle) is not particularly limited, but is preferably about 35 to 65 °. In particular, the irradiation angle is more preferably about 42 to 47 ° or 52 to 57 °. By irradiating the surface of the lower electrode 13 with such an irradiation angle, the ferroelectric film 24 having tetragonal (001) orientation and in-plane orientation can be formed.

  The ion beam acceleration voltage is preferably about 100 to 300V, and more preferably about 150 to 250V.

  The ion beam dose is preferably about 1 to 30 mA, more preferably about 5 to 15 mA.

  According to such a method of forming the ferroelectric film 24, it is possible to adjust the alignment direction to be aligned in an arbitrary direction by a simple method of adjusting the irradiation angle of the ion beam. In addition, since the orientation direction of the ferroelectric film can be accurately aligned as described above, there is an advantage that the average thickness of the ferroelectric film 24 can be further reduced.

  As described above, the ferroelectric film 24 is obtained.

[3A] Lower Electrode Extraction Step Next, a part of the ferroelectric film 24 is removed, and the lower electrode 13 is extracted. This can be done, for example, by using a photolithography method.

  First, a resist layer is formed on the ferroelectric film 24 leaving a portion to be removed.

  Next, an etching process (for example, a wet etching process, a dry etching process, etc.) is performed on the ferroelectric film 24.

  Next, the resist layer is removed. Thereby, a part of the lower electrode 13 (left side in FIG. 1) is exposed.

[4A] Upper Electrode Formation Step Next, the upper electrode 25 is formed on the ferroelectric film 24. This can be done, for example, as follows.

  First, a mask layer having a desired pattern shape is formed on the ferroelectric film 24 by, eg, sputtering.

  Next, the material of the upper electrode 25 made of, for example, Pt is formed into a film by using, for example, a vapor deposition method, a sputtering method, a printing method, or the like.

  Next, the mask layer is removed.

  As described above, the upper electrode 25 is obtained.

  The capacitor 200 is manufactured through the steps [1A] to [4A] as described above.

<3. Configuration of Piezoelectric Device>
FIG. 3 is a cross-sectional view showing an embodiment of the piezoelectric device of the present invention and a liquid discharge head using the same.

  First, the piezoelectric device 54 shown in FIG. 3 will be described focusing on differences from the capacitor 200. The piezoelectric device 54 includes a substrate 52, an amorphous layer (vibrating plate) 53 on the substrate 52, a lower electrode 542 on the amorphous layer 53, a piezoelectric film 543 on the lower electrode 542, and an upper electrode 541 on the piezoelectric film 543. have.

  On the lower electrode 542, a piezoelectric film 543 is formed in an in-plane orientation by an ion beam assist method. As a result, the piezoelectric device 54 is improved in various characteristics such as electric field distortion characteristics. The piezoelectric film 543 can be composed of various ferroelectric materials, but preferably includes a ferroelectric material having a perovskite structure, and is mainly composed of a ferroelectric material having a perovskite structure. More preferred. Further, ferroelectric materials having a perovskite structure include those with rhombohedral (100) orientation, those with tetragonal (001) orientation, those with epitaxial growth with cubic (100) orientation, and pseudocubic crystals. Any of those that are epitaxially grown in the (100) orientation may be used, but those having the rhombohedral (100) orientation are particularly preferable. Thereby, the said effect improves more.

As the ferroelectric material having the perovskite structure, the same materials as those mentioned for the capacitor 200 can be used. In particular, Pb (M _1/3 N _2/3 ) O ₃ (M = Mg, Zn, Co, Ni, Mn, N = Nb, Ta), Pb (M _1/2 N _1/2 ) O ₃ (M = Sc, Fe, In, Yb , Ho, Lu, N = Nb, Ta), Pb (M 1/2 N 1/2) O 3 (M = Mg, Cd, Mn, Co, N = W, Re) , Pb (M _2/3 N _1/3 ) O ₃ (M = Mn, Fe, N = W, Re), or a relaxor material PMN composed of a mixed phase and Pb (Zr _x Ti _1-x ) O ₃ (PZT, 0.0 ≦ x ≦ 1.0) and solid solution PMN _y -PZT _1-y is preferably included. In particular, a solid solution of Pb (Mn _1/3 Nb _2/3 ) O ₃ and PZT and a solid solution of Pb (Zn _1/3 Nb _2/3 ) O ₃ and PZT are desirable. As a result, the piezoelectric device 54 has particularly excellent piezoelectric characteristics and other various characteristics.

  Further, the average thickness of the piezoelectric film 543 is not particularly limited, but is preferably about 100 to 3000 nm, and more preferably about 500 to 2000 nm. By setting the average thickness of the piezoelectric film 543 within the above range, it is possible to obtain a piezoelectric device that can suitably exhibit various characteristics while preventing an increase in size of the piezoelectric device 54.

  An upper electrode 541 is formed on the piezoelectric film 543. The constituent material and the average thickness of the upper electrode 541 can be the same as those of the upper electrode 25 described in the capacitor 200.

<4. Manufacturing method of piezoelectric device>
Next, a method for manufacturing a piezoelectric device will be described with reference to FIG.

  In the manufacturing method of the piezoelectric device 54 shown below, a step of forming the lower electrode 542 on the amorphous layer 53 on the substrate 52 (lower electrode forming step) and a step of forming the piezoelectric film 543 on the lower electrode 542 ( A piezoelectric film forming step), a step of forming the upper electrode 25 on the piezoelectric film 543 (upper electrode forming step), and a step of patterning the piezoelectric film and the upper electrode (patterning step). Hereinafter, each process will be described sequentially.

[1C] Lower electrode formation step This is performed in the same manner as in the step [1A].

[2C] Piezoelectric Film Formation Step Next, a piezoelectric film 543 is formed on the lower electrode 542. This can be performed by the ion beam assist method in the same manner as in the step [2A], and an in-plane oriented piezoelectric film can be formed.

[3C] Upper Electrode Formation Step Next, as shown in FIG. 4 [3C], the upper electrode 541 is formed on the piezoelectric thin film 543. Specifically, platinum (Pt) or the like is formed as the upper electrode 541 to a thickness of 100 nm by a direct current sputtering method.

[4C] Patterning Step As shown in FIG. 4 [4C], the piezoelectric thin film 543 and the upper electrode 541 are processed into a predetermined shape to form a piezoelectric device. Specifically, after a resist is spin-coated on the upper electrode 541, patterning is performed by exposing and developing into a predetermined shape. The upper electrode 541 and the piezoelectric thin film 543 are etched by ion milling or the like using the remaining resist as a mask.

  The piezoelectric device 54 is manufactured through the above steps [1C] to [4C].

<5. Configuration of Ferroelectric Memory>
Next, a ferroelectric memory provided with the ferroelectric device of the present invention as a capacitor will be described.

  FIG. 5 is a plan view schematically showing an embodiment of the ferroelectric memory of the present invention, and FIG. 6 is an enlarged view of a part of the cross section along the line AA in FIG. In FIG. 5, in order to avoid complication, a part of the hatched lines indicating the cross section is omitted.

  As shown in FIG. 6, the ferroelectric memory 40 includes a memory cell array 42 and a peripheral circuit unit 41. The memory cell array 42 and the peripheral circuit unit 41 are formed in different layers. In the present embodiment, the peripheral circuit section 41 is formed in the lower layer (lower side), and the memory cell array 42 is formed in the upper layer (upper side).

  The memory cell array 42 is arranged so that a first signal electrode (word line) 422 for selecting a row and a second signal electrode (bit line) 424 for selecting a column are orthogonal to each other. The arrangement of the signal electrodes is not limited to the above, and may be reversed. That is, the first signal electrode 422 may be a bit line and the second signal electrode 424 may be a word line.

  A ferroelectric film 423 is disposed between the first signal electrode 422 and the second signal electrode 424, and each of the unit capacitors (in the intersection region between the first signal electrode 422 and the second signal electrode 424) is provided. Memory cell).

  A first protective layer 425 made of an insulating material is formed so as to cover the first signal electrode 422, the ferroelectric film 423, and the second signal electrode 424.

  Further, a second protective layer 426 made of an insulating material is formed on the first protective layer 425 so as to cover the second wiring layer 44.

  The first signal electrode 422 and the second signal electrode 424 are each electrically connected to the first wiring layer 43 of the peripheral circuit unit 41 by the second wiring layer 44.

  As shown in FIG. 5, the peripheral circuit unit 41 includes a first drive circuit 451 for selectively controlling the first signal electrode 422 and a second drive circuit for selectively controlling the second signal electrode 424. 452 and a signal detection circuit 453 such as a sense amplifier, and information can be selectively written to or read from the unit capacitor (memory cell).

  Further, the peripheral circuit section 41 has a MOS transistor 412 formed on a semiconductor substrate 411 as shown in FIG. The MOS transistor 412 has a gate insulating layer 412a, a gate electrode 412b, and a source / drain region 412c.

  Each MOS transistor 412 is isolated by an element isolation region 413 and is electrically connected by a first wiring layer 43 formed in a predetermined pattern.

  A first interlayer insulating layer 414 is formed on the semiconductor substrate 411 on which the MOS transistor 412 is formed, and a second interlayer insulating layer 415 is formed on the first interlayer insulating layer 414 so as to cover the first wiring layer 43. Is formed.

  A memory cell array 42 is provided on the second interlayer insulating layer 415.

  The peripheral circuit unit 41 and the memory cell array 42 are electrically connected by the second wiring layer 44.

  In the present embodiment, the capacitor 200 described above is configured by the second interlayer insulating layer 415, the first signal electrode 422, the ferroelectric film 423, and the second signal electrode 424.

  Therefore, in this embodiment, at least the surface of the second interlayer insulating layer 415 is made of an amorphous material.

  According to the ferroelectric memory 40 having the above configuration, since the peripheral circuit unit 41 and the memory cell array 42 are stacked on the single semiconductor substrate 411, the peripheral circuit unit 41 and the memory cell array 42 are arranged on the same plane. Compared with the case of disposing, the chip area can be significantly reduced, and the degree of integration of unit capacitors (memory cells) can be increased.

  An example of writing and reading operations in the ferroelectric memory 40 will be described.

  First, in the read operation, the read voltage “Vo” is applied to the selected unit capacitor. This also serves as a write operation of “0” at the same time. At this time, the current flowing through the selected bit line or the potential when the bit line is set to high impedance is read by the sense amplifier.

  At this time, a predetermined voltage is applied to unselected unit capacitors in order to prevent crosstalk during reading.

  On the other hand, in the write operation, when “1” is written, a voltage of “−Vo” is applied to the selected unit capacitor. In the case of writing “0”, a voltage that does not invert the polarization of the selected unit capacitor is applied to the selected unit capacitor, and the “0” state written during the read operation is held.

  At this time, a predetermined voltage is applied to unselected unit capacitors in order to prevent crosstalk during writing.

<6. Manufacturing Method of Ferroelectric Memory>
Next, an example of a method for manufacturing the ferroelectric memory 40 will be described.

  The ferroelectric memory 40 as described above can be manufactured, for example, as follows.

  -1- First, the peripheral circuit unit 41 is formed using a known LSI process (semiconductor process).

  Specifically, a MOS transistor 412 is formed on the semiconductor substrate 411. For example, an element isolation region 413 is formed in a predetermined region on the semiconductor substrate 411 using a trench isolation method, a LOCOS method, or the like, and then a gate insulating layer 412a and a gate electrode 412b are formed. The source / drain region 412c is formed by doping.

  -2- Next, after forming the first interlayer insulating layer 414, a contact hole is formed, and then a first wiring layer 43 having a predetermined pattern is formed.

  -3- Next, a second interlayer insulating layer 415 is formed on the first interlayer insulating layer 414 on which the first wiring layer 43 is formed.

  As described above, the peripheral circuit section 41 having various circuits such as the drive circuits 451 and 452 and the signal detection circuit 453 is formed.

  −4 Next, the memory cell array 42 is formed on the peripheral circuit portion 41. This can be performed in the same manner as the above-described steps [1A] to [4A].

  −5- Next, a first protective layer 425 is formed on the ferroelectric film 423 on which the second signal electrode 424 is formed. Further, a contact hole is formed in a predetermined region of the first protective layer 425, and then Then, the second wiring layer 44 having a predetermined pattern is formed. As a result, the peripheral circuit unit 41 and the memory cell array 42 are electrically connected.

  −6 Next, the second protective layer 426 is formed as the uppermost layer.

  As described above, the memory cell array 42 is formed, and the ferroelectric memory 40 is obtained.

  Such a ferroelectric memory 40 can be applied to various electronic devices. Examples of the electronic device include a personal computer, an IC card, a tag, and a mobile phone.

<7. Configuration of Inkjet Recording Head>
An ink jet recording head which is a liquid discharge head provided with the piezoelectric device of the present invention will be described.

  FIG. 7 is an exploded perspective view showing an embodiment of the ink jet recording head of the present embodiment. FIG. 3 described above shows a cross-sectional view of the configuration of the main part of the ink jet recording head shown in FIG. In addition, FIG. 7 is shown upside down from the state normally used.

  An ink jet recording head 50 (hereinafter simply referred to as “head 50”) shown in FIG. 7 includes a nozzle plate 51, an ink chamber substrate 52, a vibration plate 53, and a piezoelectric element (vibration) joined to the vibration plate 53. Source) 54, and these are housed in a base 56. The head 50 constitutes an on-demand piezo jet head.

  The nozzle plate 51 is composed of, for example, a stainless steel rolling plate. A large number of nozzles 511 for discharging ink droplets are formed on the nozzle plate 51. The pitch between these nozzles 511 is appropriately set according to the printing accuracy.

  An ink chamber substrate 52 is fixed (fixed) to the nozzle plate 51. The ink chamber substrate 52 temporarily stores a plurality of ink chambers (cavities, pressure chambers) 521 and ink supplied from the ink cartridge 631 by the nozzle plate 51, side walls (partition walls) 522, and a vibration plate 53 described later. And a supply port 524 for supplying ink from the reservoir 523 to each ink chamber 521 is partitioned.

  These ink chambers 521 are each formed in a strip shape (cuboid shape), and are disposed corresponding to each nozzle 511. Each ink chamber 521 has a variable volume due to vibration of a diaphragm 53 described later, and is configured to eject ink by this volume change.

  As a base material for obtaining the ink chamber substrate 52, for example, a silicon single crystal substrate, various glass substrates, various plastic substrates, or the like can be used. Since these substrates are general-purpose substrates, the manufacturing cost of the head 50 can be reduced by using these substrates.

  Among these, it is preferable to use a (110) -oriented silicon single crystal substrate as a base material. Since the (110) oriented silicon single crystal substrate is suitable for anisotropic etching, the ink chamber substrate 52 can be easily and reliably formed.

  The average thickness of the ink chamber substrate 52 is not particularly limited, but is preferably about 10 to 1000 μm, and more preferably about 100 to 500 μm.

  The volume of the ink chamber 521 is not particularly limited, but is preferably about 0.1 to 100 nL, and more preferably about 0.1 to 10 nL.

  On the other hand, a vibration plate 53 is joined to the ink chamber substrate 52 on the side opposite to the nozzle plate 51, and a plurality of piezoelectric elements 54 are provided on the vibration plate 53 on the side opposite to the ink chamber substrate 52.

  Further, a communication hole 531 is formed at a predetermined position of the vibration plate 53 so as to penetrate in the thickness direction of the vibration plate 53, and the ink cartridge 631, which will be described later, is supplied to the reservoir 523 through the communication hole 531. Can be supplied.

  Each piezoelectric element 54 has a piezoelectric film 543 interposed between the lower electrode 542 and the upper electrode 541, and is disposed corresponding to the substantially central portion of each ink chamber 521. Each piezoelectric element 54 is electrically connected to a piezoelectric element driving circuit, which will be described later, and is configured to operate (vibrate, deform) based on a signal from the piezoelectric element driving circuit.

  Each of these piezoelectric elements 54 functions as a vibration source, and the vibration plate 53 vibrates due to vibration of the piezoelectric elements 54 and functions to instantaneously increase the internal pressure of the ink chamber 521.

  The base 56 is made of, for example, various resin materials, various metal materials, and the like, and the ink chamber substrate 52 is fixed and supported on the base 56.

  Such a head 50 is in a state where a predetermined ejection signal is not input via the piezoelectric element driving circuit, that is, in a state where no voltage is applied between the lower electrode 542 and the upper electrode 541 of the piezoelectric element 54. The piezoelectric film 543 is not deformed. For this reason, the vibration plate 53 is not deformed, and the volume of the ink chamber 521 is not changed. Accordingly, no ink droplet is ejected from the nozzle 511.

  On the other hand, in a state where a predetermined ejection signal is input via the piezoelectric element driving circuit, that is, in a state where a constant voltage is applied between the lower electrode 542 and the upper electrode 541 of the piezoelectric element 54, the piezoelectric film 543 is applied to the piezoelectric film 543. Deformation occurs. As a result, the diaphragm 53 is greatly deflected, and the volume of the ink chamber 521 is changed. At this time, the pressure in the ink chamber 521 increases instantaneously, and ink droplets are ejected from the nozzles 511.

  When the ejection of one ink is completed, the piezoelectric element driving circuit stops applying the voltage between the lower electrode 542 and the upper electrode 541. As a result, the piezoelectric element 54 returns almost to its original shape, and the volume of the ink chamber 521 increases. At this time, the pressure (pressure in the positive direction) from the ink cartridge 631 described later toward the nozzle 511 is applied to the ink. For this reason, air is prevented from entering the ink chamber 521 from the nozzle 511, and an amount of ink corresponding to the ink discharge amount is supplied from the ink cartridge 631 to the ink chamber 521 through the reservoir 523.

  Thus, in the head 50, arbitrary (desired) characters and figures can be printed by sequentially inputting ejection signals to the piezoelectric element 54 at the position to be printed via the piezoelectric element drive circuit. it can.

<8. Manufacturing method of ink jet recording head>
Next, an example of a method for manufacturing the head 50 will be described. The head 50 as described above can be manufactured, for example, as follows.

  −10− First, the base material to be the ink chamber substrate 52 and the vibration plate 53 are bonded (bonded) to integrate them.

  For this joining, for example, a method of performing a heat treatment in a state where the base material and the diaphragm 53 are pressure-bonded is suitably used. According to this method, the base material and the diaphragm 53 can be integrated easily and reliably.

  The heat treatment conditions are not particularly limited, but are preferably about 100 to 600 ° C. × 1 to 24 hours, and more preferably about 300 to 600 ° C. × 6 to 12 hours. For bonding, various other bonding methods, various fusion methods, and the like may be used.

  −20− Next, the piezoelectric element 54 is formed on the diaphragm 53. This can be performed in the same manner as the above-described steps [1C] to [4C].

  Next, recesses to be the ink chambers 521 are formed at positions corresponding to the piezoelectric elements 54 of the base material to be the ink chamber substrates 52, and recesses to be the reservoirs 523 and the supply ports 524 are formed at predetermined positions. .

  Specifically, after forming a mask layer in accordance with the position where the ink chamber 521, the reservoir 523, and the supply port 524 are to be formed, for example, parallel plate type reactive ion etching, inductive coupling type, electron cyclotron resonance type Dry etching such as helicon wave excitation method, magnetron method, plasma etching method, ion beam etching method, etc. Wet etching with high concentration alkaline aqueous solution such as 5 wt% to 40 wt% potassium hydroxide, tetramethylammonium hydroxide, etc. Do.

  Thus, the base material is scraped (removed) to the extent that the diaphragm 53 is exposed in the thickness direction, and the ink chamber substrate 52 is formed. At this time, the portion left unetched becomes the side wall 522, and the exposed diaphragm 53 is in a state where it can function as a diaphragm.

  When a (110) oriented silicon substrate is used as a base material, the base material is easily anisotropically etched by using the above-described high-concentration alkaline aqueous solution, so that the ink chamber substrate 52 can be formed. It becomes easy.

  −40− Next, the nozzle plate 51 on which the plurality of nozzles 511 are formed is aligned and joined so that each nozzle 511 corresponds to a recess that becomes each ink chamber 521. As a result, a plurality of ink chambers 521, a reservoir 523, and a plurality of supply ports 524 are defined.

  For this joining, for example, various adhesion methods such as adhesion with an adhesive, various fusion methods, and the like can be used.

  −50− Next, the ink chamber substrate 52 is attached to the base 56. As described above, the ink jet recording head 50 is obtained.

<9. Inkjet printer>
An ink jet printer which is a liquid ejection apparatus provided with the ink jet recording head of the present invention will be described.

  FIG. 8 is a schematic view showing an embodiment of the ink jet printer of the present embodiment. In the following description, in FIG. 8, the upper side is referred to as “upper part” and the lower side is referred to as “lower part”.

  The ink jet printer 60 shown in FIG. 8 includes an apparatus main body 62, a tray 621 for installing the recording paper P in the upper rear, a discharge port 622 for discharging the recording paper P in the lower front, and an operation panel 67 in the upper surface. And are provided.

  The operation panel 67 is composed of, for example, a liquid crystal display, an organic EL display, an LED lamp, and the like. And.

  Further, inside the apparatus main body 62, mainly, a printing apparatus (printing means) 64 having a reciprocating head unit 63 and a paper feeding apparatus (paper feeding means) for feeding the recording paper P to the printing apparatus 64 one by one. 65 and a control unit (control means) 66 for controlling the printing device 64 and the paper feeding device 65.

  Under the control of the control unit 66, the paper feeding device 65 intermittently feeds the recording paper P one by one. The recording paper P passes near the lower part of the head unit 63. At this time, the head unit 63 reciprocates in a direction substantially perpendicular to the feeding direction of the recording paper P, and printing on the recording paper P is performed. That is, the reciprocation of the head unit 63 and the. The intermittent feeding of the recording paper P is the main scanning and sub-scanning in printing, and ink jet printing is performed.

  The printing apparatus 64 includes a head unit 63, a carriage motor 641 that serves as a drive source for the head unit 63, and a reciprocating mechanism 642 that reciprocates the head unit 63 in response to the rotation of the carriage motor 641.

  The head unit 63 has an ink jet recording head 50 provided with a number of nozzles 511 at a lower portion thereof, an ink cartridge 631 that supplies ink to the ink jet recording head 50, and a carriage on which the ink jet recording head 50 and the ink cartridge 631 are mounted. 632.

  Note that full-color printing is possible by using an ink cartridge 631 that is filled with ink of four colors, yellow, cyan, magenta, and black (black). In this case, the head unit 63 is provided with the ink jet recording head 50 corresponding to each color.

  The reciprocating mechanism 642 includes a carriage guide shaft 643 whose both ends are supported by a frame (not shown), and a timing belt 644 extending in parallel with the carriage guide shaft 643.

  The carriage 632 is supported by the carriage guide shaft 643 so as to reciprocate and is fixed to a part of the timing belt 644.

  When the timing belt 644 travels forward and backward via a pulley by the operation of the carriage motor 641, the head unit 63 reciprocates while being guided by the carriage guide shaft 643. During this reciprocation, ink is appropriately discharged from the ink jet recording head 50 and printing on the recording paper P is performed.

  The sheet feeding device 65 includes a sheet feeding motor 651 as a driving source and a sheet feeding roller 652 that rotates by the operation of the sheet feeding motor 651.

  The paper feed roller 652 includes a driven roller 652a and a drive roller 652b that are vertically opposed to each other with a feeding path (recording paper P) of the recording paper P interposed therebetween. The drive roller 652b is connected to the paper feed motor 651. As a result, the paper feed roller 652 can feed a large number of recording sheets P set on the tray 621 one by one toward the printing device 64. Instead of the tray 621, a configuration in which a paper feed cassette that stores the recording paper P can be detachably mounted may be employed.

  The control unit 66 performs printing by controlling the printing device 64, the paper feeding device 65, and the like based on print data input from a host computer such as a personal computer or a digital camera.

  Although not shown, the control unit 66 mainly includes a memory that stores a control program for controlling each unit, a piezoelectric element driving circuit that drives the piezoelectric element (vibration source) 54 to control the ink ejection timing, A driving circuit for driving the printing device 64 (carriage motor 641), a driving circuit for driving the paper feeding device 65 (paper feeding motor 651), a communication circuit for obtaining print data from the host computer, and these electrically And a CPU that is connected and performs various controls in each unit.

  In addition, for example, various sensors capable of detecting a printing environment such as the remaining amount of ink in the ink cartridge 631, the position of the head unit 63, temperature, and humidity are electrically connected to the CPU.

  The control unit 66 obtains the print data via the communication circuit and stores it in the memory. The CPU processes the print data and outputs a drive signal to each drive circuit based on the process data and input data from various sensors. The piezoelectric element 54, the printing device 64, and the paper feeding device 65 are operated by this drive signal. As a result, printing is performed on the recording paper P.

<10. Other>
The ferroelectric device, the piezoelectric device, the ferroelectric memory, the electronic device, the ink jet recording head, and the ink jet printer of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to these. It is not something.

  For example, each part constituting the ferroelectric device, the piezoelectric device, the ferroelectric memory, the electronic device, the ink jet recording head, and the ink jet printer of the present invention is replaced with any one that exhibits the same function, or other Configurations can also be added.

  In addition, for example, in the manufacturing method of the ferroelectric device, the piezoelectric device, the ferroelectric memory, and the ink jet recording head, arbitrary steps can be added respectively.

  Further, the configuration of the ink jet recording head of the embodiment can be applied to, for example, a liquid discharge mechanism of various industrial liquid discharge apparatuses. In this case, the liquid ejection device has a viscosity suitable for ejection from, for example, a nozzle (liquid ejection port) of the liquid ejection mechanism, in addition to the ink (color dye inks such as yellow, cyan, magenta, and black) as described above. It is possible to use a solution or a liquid substance having the same.

It is sectional drawing of the capacitor which is a ferroelectric device of this invention. It is a figure for demonstrating the manufacturing method of the ferroelectric device of this invention. It is sectional drawing which shows embodiment of the piezoelectric material device of this invention, and a liquid discharge head using the same. It is a figure for demonstrating the manufacturing method of a piezoelectric material device. 1 is a plan view schematically showing an embodiment of a ferroelectric memory of the present invention. It is the sectional view on the AA line in FIG. 1 is an exploded perspective view showing an embodiment of an ink jet recording head that is a liquid discharge head of the present invention. FIG. 1 is a schematic view showing an embodiment of an ink jet printer which is a liquid ejection apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Board | substrate, 13 ... Lower electrode, 15 ... Amorphous layer, 200 ... Capacitor, 24 ... Ferroelectric film, 25 ... Upper electrode, 40 ... Ferroelectric memory, 41 ... Peripheral circuit part, 411 ... Semiconductor substrate, 412 ... MOS transistor, 412a ... gate insulating layer, 412b ... gate electrode, 412c ... source / drain region, 413 ... element isolation region, 414 ... first interlayer insulating layer, 415 ... second interlayer insulating layer, 42 ... memory cell array, 422 ... First signal electrode, 423 ... ferroelectric film, 424 ... second signal electrode, 425 ... first protective layer, 426 ... second protective layer, 43 ... first wiring layer, 44 ... second wiring layer, 451 ... first 1 drive circuit, 452 ... second drive circuit, 453 ... signal detection circuit, 50 ... ink jet recording head, 51 ... nozzle plate, 511 ... nozzle, 52 ... ink chamber substrate, 521 ... i 522 ... side wall, 523 ... reservoir, 524 ... supply port, 53 ... diaphragm, 531 ... communication hole, 54 ... piezoelectric element, 541 ... upper electrode, 542 ... lower electrode, 543 ... piezoelectric film, 56 ... substrate , 60 ... inkjet printer, 62 ... device main body, 621 ... tray, 622 ... paper discharge port, 63 ... head unit, 631 ... ink cartridge, 632 ... carriage, 64 ... printing device, 641 ... carriage motor, 642 ... reciprocating mechanism 643 ... Carriage guide shaft, 644 ... Timing belt, 65 ... Paper feed device, 651 ... Paper feed motor, 652 ... Paper feed roller, 652a ... Driven roller, 652b ... Drive roller, 66 ... Controller, 67 ... Operation panel, P ... Recording paper

Claims (3)

The lower electrode is formed on the substrate, wherein the piezoelectric film is formed by ion beam assisted deposition on the lower electrode, an upper electrode on said piezoelectric film, a manufacturing method of the piezoelectric device, wherein When forming the piezoelectric film, the normal angle of the lower electrode surface and the irradiation angle formed by the ion beam are 35 ° to 65 °, and the piezoelectric film is made of Pb (Mn _1/3 Nb _2/3 ) O. ₃ and Pb (Zr _x Ti _1-x ) O ₃ (0 ≦ x ≦ 1.0) or Pb (Zn _1/3 Nb _2/3 ) O ₃ and Pb (Zr _x Ti _1-x ) O ₃ (0 ≦ x ≦ 1.0) a method of manufacturing a piezoelectric device, which includes at least one of solid solutions, and has tetragonal (001) orientation and in-plane orientation   A step of forming a piezoelectric device by the manufacturing method according to claim 1; a step of forming a cavity whose internal volume changes by deformation of the piezoelectric film of the piezoelectric device in the substrate of the piezoelectric device; A method for manufacturing a liquid discharge head comprising: A method for manufacturing a liquid discharge apparatus, wherein the liquid discharge head formed by the manufacturing method according to claim 2 is used.

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