JP2008124342A - Actuator device, liquid jet head, and liquid jet device - Google Patents

Abstract

An actuator device, a liquid ejecting head, and a liquid ejecting device capable of preventing destruction of a piezoelectric layer due to driving of a piezoelectric element are provided.
A piezoelectric element includes: a lower electrode film provided on a substrate; a piezoelectric layer provided on the lower electrode film; and an upper electrode film provided on the piezoelectric layer; and The ratio of the thickness and width of each crystal grain of the piezoelectric layer 70 constituting the piezoelectric element 300 is set to be 1 or more and 100 or less.
[Selection] Figure 3

Description

  The present invention relates to an actuator device having a piezoelectric element composed of a lower electrode film, a piezoelectric layer made of a piezoelectric material, and an upper electrode film so that the piezoelectric element can be bent and deformed, and a liquid ejecting head and a liquid ejecting apparatus using the actuator device.

  As a piezoelectric element used as an actuator device or the like, for example, a piezoelectric material having an electromechanical conversion function, for example, a piezoelectric layer made of crystallized piezoelectric ceramics, and the like, two electrodes of a lower electrode film and an upper electrode film are used. There is something that is sandwiched between. As an actuator device having a piezoelectric element, that is, a device using an actuator device in a flexural vibration mode, for example, there is a liquid ejecting head that ejects liquid droplets from a nozzle opening using displacement of a piezoelectric element. As a typical example of the liquid ejecting head, for example, a part of a pressure generation chamber communicating with a nozzle opening for ejecting ink droplets is configured by a vibration plate, and the vibration plate is deformed by a piezoelectric element so that ink in the pressure generation chamber is formed. And an ink jet recording head that discharges ink droplets from a nozzle opening by pressurizing. In addition, the piezoelectric layer constituting the piezoelectric element used in such an ink jet recording head is formed by laminating a piezoelectric material on a substrate provided with a lower electrode, for example, and extending in the film thickness direction. It is formed of crystals (for example, see Patent Document 1).

JP-A-10-81016

  If the piezoelectric layer is thus formed of columnar crystals extending in the film thickness direction, cracks may occur at crystal grain boundaries (between crystals) due to the driving of the piezoelectric element. In other words, since there is an amorphous portion in which the piezoelectric material is not crystallized at the crystal grain boundary, the crystal grain boundary is continuous in the thickness direction of the piezoelectric layer, so that the piezoelectric layer is cracked. Is likely to occur.

  Such a problem exists not only in an actuator device mounted on a liquid ejecting head such as an ink jet recording head, but also in an actuator device mounted on other than the liquid ejecting head.

  SUMMARY An advantage of some aspects of the invention is that it provides an actuator device, a liquid ejecting head, and a liquid ejecting apparatus that can prevent a piezoelectric layer from being destroyed by driving a piezoelectric element. .

The present invention for solving the above-described problems comprises a piezoelectric element comprising a lower electrode film provided on a substrate, a piezoelectric layer provided on the lower electrode film, and an upper electrode film provided on the piezoelectric layer. The piezoelectric layer constituting the piezoelectric element includes a plurality of crystal grains stacked without being continuous in the film thickness direction, and the ratio between the thickness and width of each crystal grain is 1 or more and 100 or less. The actuator device is characterized by the following.
In the present invention, since the rigidity of the piezoelectric layer is improved, it is possible to prevent the piezoelectric layer from being cracked by the repeated driving of the piezoelectric element.

  Here, it is preferable that the ends of the crystal grains of the piezoelectric layer are not aligned in the thickness direction of the piezoelectric layer. In such a configuration, since there is no grain boundary linearly continuous in the film thickness direction in the piezoelectric layer, it is possible to more reliably prevent cracks from occurring in the piezoelectric layer.

  The crystal grains of the piezoelectric layer are preferably formed without preferential orientation in one direction in the plane direction of the piezoelectric layer. As a result, the piezoelectric layer can be formed relatively easily, and the rigidity of the piezoelectric layer can be improved more reliably.

  The crystal grains of the piezoelectric layer are preferably preferentially oriented in one direction in the plane direction of the piezoelectric layer. Thereby, the thickness of the crystal grains can be made relatively thick, and the displacement characteristics can be maintained extremely well while increasing the rigidity of the piezoelectric layer.

  Further, when each crystal grain of the piezoelectric layer is preferentially oriented in one direction in the plane direction of the piezoelectric layer, the piezoelectric element is formed so that the cross section is substantially rectangular, The direction in which the crystal grains of the body layer are preferentially oriented is preferably the longitudinal direction or the short direction of the piezoelectric element. Thereby, it is possible to more reliably prevent cracks from being generated in the piezoelectric layer due to repeated driving of the piezoelectric element.

  Moreover, it is preferable that the space | interval of each crystal grain of the said piezoelectric material layer is 5 nm or less. By regulating the interval between crystal grains that are relatively susceptible to cracks in this way, it is possible to more reliably prevent cracks from occurring in the piezoelectric layer due to repeated driving of the piezoelectric elements. Furthermore, the film thickness of the piezoelectric layer is preferably 0.5 to 5 μm. Thereby, the displacement characteristic of the piezoelectric element can be favorably maintained while increasing the rigidity of the piezoelectric layer.

  Further, the present invention includes the actuator device as described above, and a flow path forming substrate in which the actuator device is provided on one side and provided with a pressure generation chamber communicating with a nozzle opening for discharging droplets. The liquid ejecting head is characterized by the above. According to the present invention, a liquid jet head with improved durability can be realized.

  According to another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head. According to the present invention, a liquid ejecting apparatus with improved reliability can be realized.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is an exploded perspective view showing a schematic configuration of an ink jet recording head which is an example of a liquid jet head according to an embodiment of the present invention. FIG. 2 is a plan view of FIG. FIG. 3 is a top view and a cross-sectional view showing an outline of the crystal state of the piezoelectric layer.

As shown in the figure, the flow path forming substrate 10 is made of a silicon single crystal substrate having a crystal plane orientation of (110) in this embodiment, and one surface thereof is made of silicon oxide (SiO ₂ ) previously formed by thermal oxidation. An elastic film 50 having a thickness of 0.5 to 2.0 [μm] is formed. In the flow path forming substrate 10, a plurality of pressure generating chambers 12 partitioned by a partition wall 11 are arranged in parallel in the width direction.

  Further, an ink supply path 13 and a communication path 14 that are partitioned by a partition wall 11 and communicate with each pressure generation chamber 12 are provided on one end side in the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10. Furthermore, a communication portion 15 that communicates with each communication path 14 is provided outside the communication path 14. The communication portion 15 communicates with a reservoir portion 32 of the protective substrate 30 described later, and constitutes a part of the reservoir 100 that becomes a common ink chamber (liquid chamber) of each pressure generating chamber 12.

  Here, the ink supply path 13 is formed to have a narrower cross-sectional area than the pressure generation chamber 12, and the flow path resistance of the ink flowing into the pressure generation chamber 12 from the communication portion 15 is kept constant. . For example, in this embodiment, the ink supply path 13 has a width smaller than the width of the pressure generation chamber 12 by narrowing the flow path on the pressure generation chamber 12 side between the reservoir 100 and each pressure generation chamber 12 in the width direction. It is formed with. In this embodiment, the ink supply path is formed by narrowing the width of the flow path from one side. However, the ink supply path may be formed by narrowing the width of the flow path from both sides. Further, the ink supply path may be formed by narrowing from the thickness direction instead of narrowing the width of the flow path. Each communication passage 14 is formed by extending the partition walls 11 on both sides in the width direction of the pressure generating chamber 12 toward the communication portion 15 to partition the space between the ink supply path 13 and the communication portion 15. Yes.

  In this embodiment, a silicon single crystal substrate is used as a material for the flow path forming substrate 10, but of course, the material is not limited to this, and for example, glass ceramics, stainless steel, or the like may be used.

  On the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 13 is provided with adhesive or heat. It is fixed by a welding film or the like. The nozzle plate 20 is made of, for example, glass ceramics, a silicon single crystal substrate, stainless steel, or the like.

  On the other hand, an elastic film 50 having a thickness of, for example, about 1.0 [μm] is formed on the side opposite to the opening surface of the flow path forming substrate 10 as described above. An insulator film 55 made of zirconium oxide or the like and having a thickness of, for example, about 0.4 [μm] is formed. Further, on the insulator film 55, a lower electrode film 60 having a thickness of, for example, about 0.1 to 0.2 [μm] and a piezoelectric film having a thickness of, for example, about 0.5 to 5 [μm]. A piezoelectric element 300 including the body layer 70 and the upper electrode film 80 having a thickness of, for example, about 50 [nm] is formed. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode is patterned together with the piezoelectric layer 70 for each pressure generating chamber 12 to form individual electrodes. Here, the piezoelectric element 300 and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as an actuator device. In the above-described example, the elastic film 50, the insulator film 55, and the lower electrode film 60 function as a diaphragm. However, the elastic film 50 and the insulator film 55 are not provided, and only the lower electrode film 60 is left. The electrode film 60 may be a diaphragm. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm. Further, a lead electrode 90 made of, for example, gold (Au) or the like is connected to the upper electrode film 80 of each piezoelectric element 300, and is selectively connected to each piezoelectric element 300 via the lead electrode 90. A voltage is applied to.

  Here, in this embodiment, the lower electrode film 60 constituting the piezoelectric element 300 is continuously formed in a region corresponding to the plurality of piezoelectric elements 300 and serves as a common electrode common to the plurality of piezoelectric elements 300. . The material of the lower electrode film 60 is not particularly limited. For example, platinum (Pt), iridium (Ir), or the like is preferably used.

  The piezoelectric layer 70 is patterned in a region facing each pressure generating chamber 12 and exists independently. The piezoelectric layer 70 is composed of a plurality of piezoelectric films 72 made of a piezoelectric material such as lead zirconate titanate (PZT) and crystallized. As shown in FIG. 3, the crystal grains 70a constituting the piezoelectric layer 70 are stacked without being continuous in the film thickness direction. The method for forming the piezoelectric layer 70 will be described later in detail.

  Here, the ratio of the thickness and the width of each crystal grain 70a constituting the piezoelectric layer 70 is 1 or more and 100 or less. Specifically, the width of the crystal grain 70a is the width, that is, the diameter of the crystal grain 70a in the in-plane direction of the piezoelectric layer 70. The crystal grain 70a of the piezoelectric layer 70 has a thickness and a crystal grain size. The ratio of the minimum diameter of 70a is 1 or more, and the ratio of the thickness to the maximum diameter is 100 or less. The ratio between the thickness and the width of each crystal grain 70a of the piezoelectric layer 70 may be in the above range, but is preferably 2 or more, and more preferably 5 or more. In particular, the ratio between the thickness t1 and the width w1 of the piezoelectric layer 70 in the cross section along the longitudinal direction of the piezoelectric element 300 is preferably relatively large, and specifically 10 or more is desirable. .

  With such a configuration, the rigidity of the piezoelectric layer 70 is substantially improved, so that the piezoelectric layer 70 is prevented from being broken due to repeated driving of the piezoelectric element 300, that is, the occurrence of cracks in the piezoelectric layer 70 is prevented. can do. Therefore, the durability of the piezoelectric element 300 is greatly improved.

  In addition, it is preferable that the ends of the crystal grains 70 a of the piezoelectric layer 70 are not aligned in the thickness direction of the piezoelectric layer 70. Since there are amorphous portions that are not substantially crystallized between the crystal grains 70a constituting the piezoelectric layer 70 (crystal grain boundaries), the end portions of the crystal grains 70a of the piezoelectric layer 70 are present. This is because cracks are likely to occur in the crystal grain boundaries (amorphous portions) when the piezoelectric layers 70 are arranged in the thickness direction. Further, since the crystal grain boundaries are not linearly continuous in the film thickness direction of the piezoelectric layer 70, the lead component of the piezoelectric layer 70 is prevented from diffusing into the lower electrode film through the crystal grain boundaries. There is also an effect that can be done.

  Furthermore, the interval between the crystal grains 70a constituting the piezoelectric layer 70, that is, the width of the crystal grain boundary is preferably 5 nm or less. As a result, the rigidity of the piezoelectric layer 70 is more reliably increased, and the occurrence of cracks in the piezoelectric layer 70 can be more reliably prevented. Moreover, the diffusion of the lead component can be prevented more reliably.

  In addition, the crystal grains 70 a of the piezoelectric layer 70 according to the present embodiment are formed without being preferentially oriented in one direction in the plane direction of the piezoelectric layer 70. That is, the piezoelectric layer 70 is formed without restricting the width of each crystal grain 70a in the in-plane direction. When the crystal grains 70 a of the piezoelectric layer 70 are formed without being preferentially oriented in one direction in the plane direction of the piezoelectric layer 70 as in the present embodiment, each piezoelectric film constituting the piezoelectric layer 70 72 is preferably formed as thin as possible. In other words, the piezoelectric layer 70 is desirably formed by stacking as many thin piezoelectric films 72 as possible.

  Thus, by thinning each piezoelectric film 72 constituting the piezoelectric layer 70, the crystal grains 70a are not formed in a columnar shape in the film thickness direction, and the width (diameter) of the crystal grains 70a is increased. . As a result, the rigidity of the piezoelectric layer 70 is further improved, and the occurrence of cracks in the piezoelectric layer 70 can be more reliably prevented. Further, by reducing the thickness of the piezoelectric film 72, the width of each crystal grain boundary becomes relatively wide. Thereby, the rigidity of the piezoelectric layer 70 can be increased and the amount of displacement of the piezoelectric layer 70 can be ensured. However, if the width of the crystal grain boundary is too wide, it causes a reduction in the displacement characteristics of the piezoelectric element 300. Therefore, the width of the crystal grain boundary is preferably 5 nm or less.

In addition, as a material of the piezoelectric layer 70, for example, in addition to a piezoelectric material such as lead zirconate titanate (PZT), a relaxor strength obtained by adding a metal such as niobium, nickel, magnesium, bismuth or yttrium to the piezoelectric material. A dielectric or the like may be used. The composition may be appropriately selected in consideration of the characteristics and application of the piezoelectric element. For example, PbTiO ₃ (PT), PbZrO ₃ (PZ), Pb (Zr _x Ti _1-x ) O ₃ (PZT) , Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT), Pb (Zn _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PZN-PT), Pb (Ni _{1 / 3 Nb 2/3) O 3 -PbTiO 3} (PNN-PT), Pb (In 1/2 Nb 1/2) O 3 -PbTiO 3 (PIN-PT), Pb (Sc 1/3 Ta 2/3) _{O 3 -PbTiO 3 (PST-PT} ), Pb (Sc 1/3 Nb 2/3) O 3 -PbTiO 3 (PSN-PT), BiScO 3 -PbTiO 3 (BS-PT), BiYbO 3 -PbTiO 3 ( BY-PT Etc. The.

  The upper electrode film 80 is patterned in a region facing each pressure generating chamber 12 together with the piezoelectric layer 70 to form individual electrodes of each piezoelectric element 300. The material of the upper electrode film 80 is not particularly limited as long as it is a highly conductive material. For example, iridium (Ir) or platinum (Pt) is preferably used.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, a protective substrate 30 having a piezoelectric element holding portion 31 for protecting the piezoelectric element 300 is bonded by, for example, an adhesive 35. Note that the space defined by the piezoelectric element holding portion 31 may be sealed or may not be sealed. Further, the protective substrate 30 is provided with a reservoir portion 32 that constitutes at least a part of the reservoir 100 in which the ink supplied to the plurality of pressure generating chambers 12 is stored. In this embodiment, the reservoir portion 32 is formed through the protective substrate 30 in the thickness direction and across the width direction of the pressure generating chamber 12, and the communication portion 15 of the flow path forming substrate 10 as described above. And the reservoir 100 is configured. Alternatively, the communication portion 15 of the flow path forming substrate 10 may be divided into a plurality of pressure generation chambers 12 and only the reservoir portion 32 may be used as the reservoir. Further, for example, only the pressure generation chamber 12 is provided in the flow path forming substrate 10, and a reservoir and a member interposed between the flow path forming substrate 10 and the protective substrate 30 (for example, the elastic film 50, the insulator film 55, etc.) An ink supply path 13 that communicates with each pressure generation chamber 12 may be provided.

  As such a protective substrate 30, it is preferable to use a material substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10, for example, a glass material, a ceramic material, etc., and in this embodiment, the same as the flow path forming substrate 10. The material is a silicon single crystal substrate.

  Further, the protective substrate 30 is provided with a through-hole 33 that penetrates the protective substrate 30 in the thickness direction, and the vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is in the through-hole 33. Exposed. On the protective substrate 30, a driving circuit 200 for driving the piezoelectric elements 300 arranged in parallel, for example, a circuit board, a semiconductor integrated circuit (IC), and the like are fixed. The drive circuit 200 and the lead electrode 90 are electrically connected by a connection wiring 210 made of a conductive wire such as a bonding wire extending in the through hole 33.

  In addition, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 [μm]). The direction is sealed. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 [μm]). A region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, and one surface of the reservoir 100 is sealed only with a flexible sealing film 41. ing.

  In such an ink jet recording head of this embodiment, ink is taken in from an ink introduction port connected to an external ink supply means (not shown), and the interior from the reservoir 100 to the nozzle opening 21 is filled with ink. In accordance with the recording signal from, pressure is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generation chamber 12 to bend and deform the piezoelectric element 300, whereby the pressure in each pressure generation chamber 12 is changed. And the ink droplets are ejected from the nozzle openings 21.

  Hereinafter, a method for manufacturing such an ink jet recording head will be described with reference to FIGS. 4 to 7 are cross-sectional views in the longitudinal direction of the pressure generating chamber.

First, as shown in FIG. 4A, a flow path forming substrate wafer 110 on which a plurality of flow path forming substrates 10 are integrally formed is thermally oxidized in a diffusion furnace at about 1100 ° C., and an elastic film is formed on the surface thereof. A silicon dioxide film 51 made of silicon dioxide (SiO ₂ ) constituting 50 is formed.

Next, as shown in FIG. 4B, an insulator film 55 made of zirconium oxide is formed on the elastic film 50 (silicon dioxide film 51). Specifically, an insulator film mainly composed of zirconium (Zr) is formed on the elastic film 50 (silicon dioxide film 51) by, for example, sputtering, and then the insulator film 55 is thermally oxidized in a diffusion furnace. Thus, the insulator film 55 made of zirconium oxide (ZrO ₂ ) is obtained.

  Next, as shown in FIG. 4C, the lower electrode film 60 is formed on the insulator film 55, and the lower electrode film 60 is patterned into a predetermined shape. Specifically, the lower electrode film 60 is formed by sequentially stacking platinum (Pt) and iridium (Ir) on the insulator film 55 by, for example, a sputtering method. In addition, the formation method of the lower electrode film 60 is not limited to sputtering method, For example, CVD method (chemical vapor deposition method) etc. may be sufficient.

  Next, as shown in FIG. 4D, a piezoelectric layer 70 is formed on the lower electrode film 60. Here, examples of the method for forming the piezoelectric layer 70 include a MOD (Metal-Organic Decomposition) method, a sol-gel method, a sputtering method, and a CVD method. Then, the piezoelectric layer 70 may be formed by any one of these methods, or the piezoelectric layer 70 may be formed by combining a plurality of methods. For example, in the present embodiment, a so-called sol-gel method is obtained in which a so-called sol in which a metal organic material is dissolved and dispersed in a solvent is applied and dried to be gelled and then baked at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. Is used to form the piezoelectric layer 70.

As a specific procedure for forming the piezoelectric layer 70, first, as shown in FIG. 5A, a piezoelectric precursor film 71, which is a PZT precursor film, is formed on the lower electrode film 60 in a single layer. That is, a sol (solution) containing a metal organic compound is applied onto the flow path forming substrate 10 on which the lower electrode film 60 is formed (application process). Next, the piezoelectric precursor film 71 is heated to a predetermined temperature and dried for a predetermined time (drying step). Next, the dried piezoelectric precursor film 71 is degreased by heating it to a predetermined temperature and holding it for a predetermined time (degreasing step). Here, degreasing refers, the organic components contained in the piezoelectric precursor film 71, for _example, is to be detached as _{NO 2, CO 2, H 2} O or the like. Next, the piezoelectric precursor film 71 is crystallized by being heated to a predetermined temperature and held for a predetermined time to form the piezoelectric film 72 (firing step). As a heating apparatus used in such a drying process, a degreasing process, and a baking process, for example, a diffusion furnace or an RTP (Rapid Thermal Processing) apparatus that heats by irradiation with an infrared lamp can be used.

  After forming the first layer of the piezoelectric film 72 on the lower electrode film 60 in this way, as shown in FIG. 5B, the lower electrode film 60 and the first piezoelectric film 72 are simultaneously patterned, The lower electrode film 60 is formed in a predetermined shape. Thereafter, the piezoelectric film forming process including the coating process, the drying process, the degreasing process, and the baking process described above is repeated a plurality of times, so that a predetermined thickness including a plurality of layers of piezoelectric films 72 as illustrated in FIG. The piezoelectric layer 70 is formed.

  Here, as described above, the piezoelectric layer 70 according to the present embodiment is formed by stacking a large number of thin piezoelectric films 72. Specifically, for example, the piezoelectric layer 70 having a thickness of 1.0 [μm] is formed by laminating ten piezoelectric films 72 having a thickness of about 0.1 [μm]. The thickness of the piezoelectric layer 70 is not particularly limited, but is preferably about 0.5 to 5 [μm].

  After the piezoelectric layer 70 is formed in this way, as shown in FIG. 6A, for example, an upper electrode film 80 made of iridium (Ir) is formed on the entire surface of the flow path forming substrate wafer 110, and the piezoelectric layer is formed. The piezoelectric layer 300 is formed by patterning the body layer 70 and the upper electrode film 80 in a region facing each pressure generating chamber 12.

  Next, the lead electrode 90 is formed. Specifically, as shown in FIG. 6B, after forming a metal layer 91 made of, for example, gold (Au) over the entire surface of the flow path forming substrate wafer 110, the metal layer 91 is For example, the lead electrode 90 is formed by patterning each piezoelectric element 300 via a mask pattern (not shown) made of a resist or the like.

  Next, as shown in FIG. 6C, a protective substrate wafer 130 that is a silicon wafer and serves as a plurality of protective substrates 30 is bonded to the piezoelectric element 300 side of the flow path forming substrate wafer 110. Then, as shown in FIG. 7A, the flow path forming substrate wafer 110 is processed to a predetermined thickness.

  Next, as shown in FIG. 7B, a protective film 52 is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, as shown in FIG. 7C, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) using an alkaline solution such as KOH, for example, using the protective film 52 as a mask. The pressure generating chamber 12, the ink supply path 13, the communication path 14, the communication part 15 and the like are formed.

  Thereafter, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are removed by cutting, for example, by dicing. The nozzle plate 20 having the nozzle openings 21 formed on the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer 130 is bonded, and the compliance substrate 40 is bonded to the protective substrate wafer 130. By dividing the flow path forming substrate wafer 110 and the like into the flow path forming substrate 10 and the like of one chip size as shown in FIG. 1, the ink jet recording head of this embodiment is obtained.

(Embodiment 2)
FIG. 8 is a top view and a cross-sectional view schematically showing the crystal structure of the piezoelectric layer according to the second embodiment. This embodiment is an example in which the crystal grains 70a of the piezoelectric layer 70A are preferentially oriented in one direction in the in-plane direction of the piezoelectric layer 70A, and other configurations are the same as those of the first embodiment. In addition, the same code | symbol is attached | subjected to the same member and the overlapping description is abbreviate | omitted.

  The crystal grains 70 a constituting the piezoelectric layer 70 </ b> A according to the present embodiment are preferentially oriented along one direction in the in-plane direction of the piezoelectric element 300. In other words, 60% or more of the crystal grains 70a of the piezoelectric layer 70A are formed in a column shape along one direction in the in-plane direction of the piezoelectric layer 70A as shown in FIG. In addition, the direction in which the crystal grains 70a of the piezoelectric layer 70A are preferentially oriented, that is, the long side direction of the crystal grains 70a preferably coincides with the longitudinal direction or the short direction of the piezoelectric element 300 having a substantially rectangular shape. . For example, the piezoelectric layer 70 </ b> A according to the present embodiment is formed such that the crystal grains 70 a are preferentially oriented along the longitudinal direction of the piezoelectric element 300.

  Even in such a configuration, as in the case of the first embodiment, the rigidity of the piezoelectric layer 70A is improved, and it is possible to prevent the piezoelectric layer 70A from being cracked by the repeated driving of the piezoelectric element 300. Play.

  The piezoelectric layer 70A in which the crystal grains 70a are preferentially oriented is formed by causing a temperature gradient in the in-plane direction of the piezoelectric precursor film 71 when performing the above-described firing step. Can do. For example, the flow path forming substrate wafer 110 on which the piezoelectric precursor film 71 is formed is inserted into the diffusion furnace heated to a predetermined temperature while being gradually moved, whereby a temperature gradient is applied to the piezoelectric precursor film 71. Occurs. Then, by generating a temperature gradient in the piezoelectric precursor film 71 in this way, the piezoelectric film 72A (piezoelectric layer 70A) in which the crystal grains 70a are preferentially oriented along the direction of the temperature gradient is formed. The method for causing the temperature gradient in the piezoelectric precursor film 71 is not limited to the above-described method, and when the piezoelectric precursor film 71 is heated, the piezoelectric precursor film 71 and, for example, an infrared lamp or the like The heat source may be relatively moved at a constant direction and at a constant speed.

  In addition, when the temperature gradient is generated in the piezoelectric precursor film 71 and the crystal grains 70a of the piezoelectric layer 70A are preferentially oriented as described above, the crystal grains 70a are formed regardless of the thickness of the piezoelectric film 72A. It is not formed in a columnar shape in the film thickness direction. For this reason, it is preferable that the film thickness of each piezoelectric film 72A constituting the piezoelectric layer 70A is relatively thick. For example, in the present embodiment, the piezoelectric layer 70A is formed by stacking only four layers of piezoelectric films 72A having a thickness of about 0.3 [μm]. Thereby, the displacement characteristics of the piezoelectric layer 70A can be maintained well while increasing the rigidity of the piezoelectric layer 70A.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment.

  Such an ink jet recording head constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 9 is a schematic perspective view showing an example of the ink jet recording apparatus. As shown in FIG. 9, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively.

  The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  In this embodiment, the ink jet recording head has been described as an example of the liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads, and ejects liquid other than ink. Of course, this method can also be applied. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

  The present invention is not limited to a method for manufacturing an actuator device mounted on a liquid ejecting head typified by an ink jet recording head, and can also be applied to a method for manufacturing an actuator device mounted on another device.

FIG. 2 is an exploded perspective view illustrating a schematic configuration of the recording head according to the first embodiment. 2A and 2B are a top view and a cross-sectional view of the recording head according to the first embodiment. FIG. 3 is a top view and a cross-sectional view illustrating an outline of a crystal state of a piezoelectric layer according to Embodiment 1. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. FIG. 6 is a top view and a cross-sectional view schematically showing a crystal state of a piezoelectric layer according to a second embodiment. 1 is a schematic perspective view showing a recording apparatus according to an embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 13 Ink supply path, 14 Communication path, 15 Communication part, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Piezoelectric element holding part, 32 Reservoir part, 40 Compliance board, 50 elastic film, 55 insulator film, 60 lower electrode film, 70, 70A piezoelectric layer, 70a crystal, 71 piezoelectric precursor film, 72, 72A piezoelectric film, 80 upper electrode film, 90 lead electrode, 100 reservoir, 300 Piezoelectric element

Claims (9)

  A piezoelectric element comprising: a lower electrode film provided on a substrate; a piezoelectric layer provided on the lower electrode film; and an upper electrode film provided on the piezoelectric layer, and constituting the piezoelectric element An actuator device characterized in that the piezoelectric layer includes a plurality of crystal grains stacked without being continuous in the film thickness direction, and the ratio between the thickness and width of each crystal grain is 1 or more and 100 or less.   2. The actuator device according to claim 1, wherein ends of the crystal grains of the piezoelectric layer are not arranged in the thickness direction of the piezoelectric layer.   3. The actuator device according to claim 1, wherein each crystal grain of the piezoelectric layer is formed without being preferentially oriented in one direction in the plane direction of the piezoelectric layer. 4.   3. The actuator device according to claim 1, wherein each crystal grain of the piezoelectric layer is preferentially oriented in one direction in a plane direction of the piezoelectric layer.   5. The piezoelectric element is formed so as to have a substantially rectangular cross section, and a direction in which crystal grains of the piezoelectric layer are preferentially oriented is a longitudinal direction or a short direction of the piezoelectric element. The actuator device described in 1.   The actuator device according to claim 1, wherein an interval between crystal grains of the piezoelectric layer is 5 nm or less.   The actuator device according to claim 1, wherein the piezoelectric layer has a thickness of 0.5 to 5 μm.   An actuator device according to any one of claims 1 to 7, and a flow path forming substrate in which the actuator device is provided on one surface side and provided with a pressure generation chamber communicating with a nozzle opening for discharging droplets; A liquid ejecting head comprising:   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 8.