Liquid dispensing head, liquid dispensing unit, device for dispensing liquid, and method for manufacturing a liquid dispensing head

Abstract

To provide a liquid discharge head capable of reducing a production cost by reducing the number of components and capable of carrying out a favorable discharge.SOLUTION: In a liquid discharge head discharging the liquid by oscillation of a nozzle plate having the layer including a substrate, diaphragm and AlN, and an electrode, polarization inversion of the layer including AlN is performed. The layer is characterized by having the composition represented by formula (1): Al1-xScxN by replacement of a part of Al in AlN with Sc, or by having the composition represented by formula (2): Al1-x(Mg,β)xN by replacement of a part of Al in AlN with Mg and tetravalent element. Here, in formulas (1) and (2), 0<x<1, and β in formula (2) represents a tetravalent element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a liquid dispensing head, a liquid dispensing unit, a device for dispensing liquid, and a method for manufacturing a liquid dispensing head. [Background technology]

[0002] In liquid dispensing heads using piezoelectric materials, studies are being conducted on the materials and component configurations of the piezoelectric material with the aim of achieving good dispensing and improving electromechanical conversion efficiency.

[0003] Patent Document 1 discloses a method for manufacturing a piezoelectric thin film comprising an aluminum nitride thin film containing scandium on a substrate, which includes a sputtering step in which aluminum and scandium are sputtered in an atmosphere containing at least nitrogen gas, such that the scandium content is in the range of 0.5 to 50 atomic percent when the total amount of scandium atoms and aluminum atoms in the aluminum nitride thin film is set to 100 atomic percent, and the temperature of the substrate in the sputtering step is in the range of 5 to 450°C. According to Patent Document 1, in a piezoelectric thin film comprising an aluminum nitride thin film with added scandium, it is possible to produce a piezoelectric thin film in which the piezoelectric response does not decrease compared to the case in which scandium is not included, even if the number of scandium atoms is in the range of 35 to 40 atomic percent.

[0004] Patent Document 2 discloses a droplet ejector comprising a piezoelectric actuator formed on at least a portion of the nozzle portion of a nozzle forming layer, with a piezoelectric element provided between first and second electrodes. The piezoelectric element is disclosed to include one or more piezoelectric materials that can be processed at temperatures lower than 450°C, and the piezoelectric element may include aluminum nitride (AlN). Patent Document 1 states that acoustic crosstalk between adjacent piezoelectric droplet ejectors on a print head can be reduced, enabling the achievement of a larger number of nozzles.

[0005] Patent Document 3 discloses a method for manufacturing a liquid dispensing head in which a nozzle plate having a substrate and a piezoelectric material vibrates to dispense liquid, wherein the piezoelectric material is formed at 450°C to 600°C. According to Patent Document 1, in a liquid dispensing head in which a liquid is dispensed by the vibration of a nozzle plate, it is possible to suppress variations in dispensing characteristics.

[0006] Patent Document 4 discloses an elastic wave device comprising a piezoelectric film made of an aluminum nitride film containing a divalent element and a tetravalent element, or a divalent element and a pentavalent element, and an electrode for exciting elastic waves propagating through the piezoelectric film. Patent Document 3 states that it is possible to obtain an elastic wave device with a large electromechanical coupling coefficient, or to suppress the increase in size of the elastic wave device.

[0007] Patent Document 5 discloses a piezoelectric thin film made of aluminum nitride containing magnesium and niobium, wherein the niobium is contained in an amount of 31 to 120 atomic percent relative to 100 atomic percent of magnesium, and the total content of magnesium and niobium relative to the sum of the content of magnesium, niobium, and aluminum is in the range of 10 to 67 atomic percent. Patent Document 5 discloses a piezoelectric film containing specified amounts of magnesium (divalent) and niobium (pentavalent) instead of scandium. According to Patent Document 5, it is possible to provide a piezoelectric thin film made of aluminum nitride that contains inexpensive elements other than scandium and has an increased piezoelectric constant. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, depending on where the piezoelectric material is formed, multiple components may be required to create the liquid introduction path, increasing the number of parts. In this case, manufacturing costs increase. Also, when using a layer containing aluminum nitride as the piezoelectric film, if the direction of polarization does not coincide with the direction of the electric field, the desired deformation cannot be achieved, and good discharge may not be possible.

[0009] Therefore, an object of the present invention is to provide a liquid discharge head capable of reducing the number of components, reducing manufacturing costs, and achieving favorable discharge. Means for Solving the Problem

[0010] In order to solve the above problem, the liquid discharge head of the present invention comprises: a deformable thin film member having an opening; and an electromechanical conversion element disposed around the opening of the thin film member and configured to deform the thin film member, wherein the electromechanical conversion element includes an electrode and an AlN-containing layer, the AlN-containing layer is capable of polarization inversion, and a part of Al in the AlN is substituted with Sc to have a composition represented by the following formula (1), or a part of Al in the AlN is substituted with Mg and a tetravalent element to have a composition represented by the following formula (2). Al 1-x Sc x N Formula (1) Al 1-x (Mg,β) x N Formula (2) wherein, in formula (1), Medium x satisfies 0<x<1, and in formula (2), x is 0.05 <x<0.43であり、 β represents a tetravalent element. Effects of the Invention

[0011] According to the present invention, it is possible to provide a liquid discharge head capable of reducing the number of components, reducing manufacturing costs, and achieving favorable discharge. Brief Description of the Drawings

[0012] [Figure 1] Fig. (a) is an explanatory perspective view and Fig. (b) is a schematic cross-sectional view along line A-A of an example of the liquid discharge head according to the present invention. [Figure 2] Fig. (a) is a schematic cross-sectional view of a main part and Fig. (b) is a schematic cross-sectional view of another example of the liquid discharge head according to the present invention. [Figure 3] It is a diagram for schematically explaining an example of the polarization direction in the AlN-containing layer. [Figure 4]FIG. (a) is a diagram for schematically explaining an example of deformation of a layer containing AlN, and FIG. (b) is a diagram for schematically explaining an example of deformation of a thin film member at that time. [Figure 5] This is a diagram for schematically explaining an example of the polarization direction and electric field direction in a layer containing AlN. [Figure 6] Schematic cross-sectional views (a) to (c) for schematically explaining another example of the polarization direction and electric field direction in a layer containing AlN. [Figure 7] This is a configuration example of a measuring apparatus for examining polarization reversal. [Figure 8A] This is an example of measurement results for a sample in which polarization reversal cannot be achieved when the configuration example of the measurement apparatus in FIG. 7 is used. [Figure 8B] This is an example of measurement results for a sample in which polarization reversal can be achieved when the configuration example of the measurement apparatus in FIG. 7 is used. [Figure 9] This is a diagram schematically showing a unit cell of hexagonal aluminum nitride. [Figure 10] This is a schematic diagram when a part of Al in hexagonal aluminum nitride is substituted with Mg and Zr. [Figure 11] This is a schematic diagram of an example of an apparatus that discharges liquid. [Figure 12] This is a schematic diagram of another example of an apparatus that discharges liquid. [Figure 13] This is a schematic diagram of an example of a liquid discharge unit. [Figure 14] This is a schematic diagram of another example of a liquid discharge unit. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a liquid discharge head, a liquid discharge unit, an apparatus for discharging liquid, and a method for manufacturing a liquid discharge head according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be modified within the range conceivable by a person skilled in the art, such as other embodiments, additions, modifications, and deletions. Any aspect is included in the scope of the present invention as long as the functions and effects of the present invention are exhibited.

[0014] The liquid discharge head of the present invention comprises: a deformable thin film member having an opening; and an electromechanical conversion element disposed around the opening of the thin film member to deform the thin film member, wherein the electromechanical conversion element includes an electrode and a layer containing AlN, the layer containing AlN is capable of polarization inversion, and a part of Al in AlN is substituted with Sc to have a composition represented by the following formula (1), or a part of Al in AlN is substituted with Mg and a tetravalent element to have a composition represented by the following formula (2).

[0015] The method for manufacturing a liquid discharge head of the present invention is a method for manufacturing a liquid discharge head, the liquid discharge head comprising: a deformable thin film member having an opening; and an electromechanical conversion element disposed around the opening of the thin film member to deform the thin film member, wherein the electromechanical conversion element includes an electrode and a layer containing AlN, the method comprises: an AlN layer forming step of forming the layer containing AlN at 450° C. or higher; and a polarization treatment step of polarizing the layer containing AlN, wherein the layer containing AlN has a composition represented by the following formula (1) in which a part of Al in AlN is substituted with Sc, or has a composition represented by the following formula (2) in which a part of Al in AlN is substituted with Mg and a tetravalent element.

[0016] Al 1-x Sc x N Formula (1) Al 1-x (Mg,β) x N Formula (2) However, in formula (1) and formula (2), x satisfies 0<x<1, and in formula (2), β represents a tetravalent element.

[0017] Figure 1 is a diagram illustrating an example of a liquid dispensing head in this embodiment. Figure 1(a) is a perspective view illustrating the liquid discharge head according to this embodiment, and Figure 1(b) is a schematic cross-sectional view of AA in Figure 1(a). This liquid discharge head 1 has a plurality of actuators 10 and a liquid chamber forming member 20.

[0018] The actuator 10 includes a deformable thin film member 102 having an opening 102a, and a piezoelectric element 103 positioned around the opening 102a of the thin film member 102 to deform the thin film member 102. The opening 102a forms a nozzle 101, from which liquid is discharged. The piezoelectric element 103 is an example of an electromechanical conversion element. The thin film member may also be referred to as a diaphragm, membrane, or the like.

[0019] The piezoelectric element 103 is formed by sequentially stacking a lower electrode 111, a layer 112 containing AlN as an electromechanical conversion film, and an upper electrode 113 on one surface of a thin film member 102. A first insulating film 115 is provided to cover the piezoelectric element 103.

[0020] Electrode wiring 116 and electrode wiring 117 are connected to the piezoelectric element 103. Electrode wiring 116 is a lower electrode lead-out wiring, and the first insulating film 115 is opened to connect it to the lower electrode 111. Electrode wiring 117 is an upper electrode lead-out wiring, and the first insulating film 115 is opened to connect it to the upper electrode 113. Electrode wirings 116 and 117 are electrically connected through openings in the insulating films.

[0021] Furthermore, a second insulating film 118 is formed on the surface of the first insulating film 115 of the piezoelectric element 103, including the surfaces of the electrode wirings 116 and 117. In addition, a protective film 119 is formed on the second insulating film 118. In this example, a protective film 119 is provided on the surface side of the first insulating film 115, covering the electrode wirings 116 and 117 connected to the piezoelectric element 103, and the second insulating film 118 is interposed between at least the electrode wirings 116 and 117 and the protective film 119.

[0022] For example, the first insulating film 115 can be an SiO2 film, the protective film 119 can be a resin film, and the second insulating film 118 can be an SiO2 film.

[0023] A liquid chamber forming member 20 is joined to the other side of the thin film member 102 of the actuator 10, and the liquid chamber forming member 20 forms a liquid chamber 201 through which the nozzle 101 (opening 102a) passes. The portion of the thin film member 102 facing the liquid chamber 201 is a displaceable portion 121.

[0024] In Figure 1(b), a water-repellent film may be provided on the protective film 119. Alternatively, protective films may be provided on the surfaces of the nozzle 101 and the liquid chamber 201.

[0025] Figure 2 is a diagram illustrating another example of the liquid dispensing head of this embodiment. Figure 2(a) shows the main part of the liquid discharge head of this embodiment. As shown in the figure, a lower electrode 111, an AlN-containing layer 112, and an upper electrode 113 are sequentially formed on the thin film member 102. Here, the lower electrode 111 and the upper electrode 113 are shown as electrodes of an electromechanical conversion element.

[0026] Figure 2(b) is another example of Figure 1(b). As shown, electrode wiring 116 is connected to wiring layer 122, which is connected to electrical connection pad 120. Wiring layer 122 is also connected to CMOS circuit 124. The CMOS circuit is an example of a drive circuit. Similarly, electrode wiring 117 is connected to wiring layer 123, which is connected to electrical connection pad 121. Wiring layer 123 is also connected to CMOS circuit 125. A drive voltage is applied through the CMOS circuit.

[0027] Next, we will explain the use of AlN (aluminum nitride) as a piezoelectric material. In this embodiment, a layer containing AlN (sometimes referred to as an AlN film, etc.) is used as the electromechanical conversion film. AlN is an example of a lead-free piezoelectric material, and the performance of AlN strongly depends on its crystallinity. Unlike ferroelectrics such as PZT (lead zirconate titanate), AlN cannot be improved by polarization treatment to enhance the electromechanical conversion (so-called piezoelectric effect) efficiency. In principle, a defect-free perfect crystal is preferable for AlN. When forming a crystal film by heating the substrate and vacuum deposition, the quality of the crystallinity depends on the substrate temperature, and the higher the temperature, the easier it is to obtain a perfect crystal.

[0028] Figure 3 schematically illustrates the direction of polarization after the formation of the AlN-containing layer 14a. When AlN is formed as a thin film on the substrate 11, it grows with the nitrogen plane (negative side) as the terminal. Therefore, as shown in Figure 3, one side of the AlN film becomes the Al plane (+) and the other side becomes the N plane (-). Polarization is taken from the positive to the negative direction, and this is defined as the forward direction. Therefore, as shown in Figure 2, the direction of polarization is taken from the Al plane to the N plane. The arrows in the figure can be said to schematically represent the polarization vectors.

[0029] For example, suppose a lower electrode is formed on a substrate 11 using Mo, an AlN film with a thickness of 1 μm is deposited on top of it, and then an upper electrode is formed on top of that. In this case, the polarization vector within the AlN film will point from top to bottom, as shown in Figure 2. For example, if the lower electrode is connected to GND and a voltage of +300V is applied to the upper electrode, this will be a forward voltage application. When a voltage is applied in this way, the AlN film will stretch in the thickness direction and contract in the plane direction (a direction perpendicular to the thickness direction).

[0030] Figure 4 is a schematic diagram illustrating an example of membrane displacement. Figure 4(a) is a schematic diagram illustrating that in the AlN-containing layer 14a, the direction of polarization (white arrow) and the direction of the electric field (black arrow) are the same. When they are in the same direction, the AlN-containing layer 14a stretches in the direction of polarization and contracts in the direction perpendicular to the direction of polarization, as shown by the dashed line. Figure 4(b) is a schematic diagram illustrating the displacement in this case. The lower electrode 111, the AlN-containing layer 14a, and the upper electrode 113 are placed on a diaphragm 12 fixed at two points, and the above voltage is applied. In this case, the diaphragm 12 bends downward as shown by the dashed line. This bending allows droplets to be ejected.

[0031] Figure 5 shows an example using two layers containing AlN, 112b and 112c, and crossed finger electrodes 131 and 132, and is a diagram to schematically explain a certain moment when a voltage is applied. The white arrows in the figure indicate the direction of polarization. As mentioned above, in the case of layers containing AlN, the direction of polarization is, for example, from the Al surface (+) to the N surface (-) (forward direction), so it is the same direction for layers containing AlN 112b and AlN 112c. The black arrows in the figure indicate the direction of application of the electric field. When crossed finger electrodes 131 and 132 as shown in Figure 4 are used, an electric field is generated from electrode 17, which is placed between layers containing AlN 14a and 14b, towards electrode 16. Therefore, the direction of application of the electric field is opposite for layers containing AlN 112b and AlN 112c.

[0032] Therefore, in layer 112b containing AlN, the direction of polarization (white arrow) and the direction of the electric field (black arrow) are in the same direction (forward direction), so it will stretch in the thickness direction and shrink in the plane direction. On the other hand, in layer 112c containing AlN, the direction of polarization (white arrow) and the direction of the electric field (black arrow) are in opposite directions, so it will shrink in the thickness direction and stretch in the plane direction.

[0033] In conventional technology, when an electric field is applied, a layer is created in which the direction of polarization (white arrow) and the direction of the electric field (black arrow) are opposite, as shown in the AlN-containing layer 112c in Figure 5. In this case, piezoelectric strain occurs in the AlN-containing layer 112b, but not in the AlN-containing layer 112c, so the piezoelectric strain cancels out. As a result, the thin film member 102 does not bend, or its bending is reduced, which is a problem.

[0034] Thus, in conventional technology, when layers containing AlN are stacked and used as a piezoelectric material, it is not possible to vibrate (bend) the diaphragm, or to vibrate it efficiently. This is because it is not possible to reverse the polarization direction of the AlN-containing layer. The reason why the polarization direction cannot be reversed is thought to be that the AlN film growth ends at the aluminum terminus.

[0035] In Figure 5, layers containing AlN are stacked, but even when the AlN layer is a single layer, a problem arises in that good ejection performance may not be obtained. Depending on how the voltage is applied, the direction of the electric field and the direction of polarization may be opposite, resulting in the desired deformation and poor ejection. For example, when a pulse voltage is applied as the driving voltage, the AlN layer may not deform at certain voltage waveforms, resulting in poor ejection. In this case as well, it is thought that the polarization of the AlN layer cannot be reversed.

[0036] Therefore, the inventors diligently conducted research to resolve the above problems and arrived at the present invention. In this embodiment, by forming an AlN-containing layer at 450°C or higher and substituting it with a specific element, the AlN-containing layer can be made to reverse its polarization. As a result, even if the direction of the electric field is opposite to the direction of polarization, the direction of polarization can be reversed, enabling good discharge. Furthermore, even when stacked, for example, piezoelectric strain cancellation does not occur, and the conversion efficiency can be improved.

[0037] On the other hand, if the temperature at which the AlN-containing layer is deposited is below 450°C, the AlN-containing layer cannot be made into a layer capable of polarization reversal. As a result, good discharge performance cannot be obtained, and the conversion efficiency cannot be improved.

[0038] Furthermore, in this embodiment, a polarization treatment is performed after forming a layer containing AlN. This allows the layer containing AlN to function as a piezoelectric material, making it a piezoelectric layer capable of polarization reversal. The polarization treatment will be described later.

[0039] Figure 6 is a diagram illustrating the polarization direction in the AlN-containing layer obtained by this embodiment. Figure 6(a) is an example where the AlN-containing layer is a single layer, and as shown in the figure, the polarization direction indicated by the white arrow is in the opposite direction to that in Figure 2, i.e., it is partially reversed. Figure 6(b) is an example where the AlN-containing layer is two layers, and Figure 6(c) is an example where the AlN-containing layer is three layers. The AlN-containing layer obtained by this embodiment is capable of polarization reversal, and in all AlN-containing layers, the direction of the electric field and the direction of polarization are in the same direction, thus preventing the cancellation of piezoelectric strain. This makes it possible to dramatically improve the conversion efficiency.

[0040] In the case of Figure 6(b), that is, when there are two layers containing AlN, the following explanation will be given using Test Examples 1 and 2 as examples. Furthermore, considering that piezoelectric strain is proportional to the electric field strength, the conversion efficiency was examined below. Test Example 1 is an example where a single layer containing AlN with a thickness of 1 μm is used. 150V is applied to the 1 μm thick layer containing AlN to deform the thin film member (diaphragm). Let the displacement at this time be X. Test Example 2 is an example in which two layers containing AlN with a thickness of 0.5 μm are stacked. In this case, when 75V is applied to each of the 0.5 μm thick AlN layers to deform the thin film member, the displacement of each layer is 0.5X, but the total displacement is X (= 0.5X + 0.5X). Therefore, the same amount of displacement can be obtained with a lower driving voltage than in Test Example 1. Furthermore, in Test Example 2, when 150V is applied to each layer containing AlN with a film thickness of 0.5 μm, the displacement of each layer is X, and the total displacement is 2X (=X+X). Therefore, twice the displacement can be obtained with the same amount of driving voltage as in Test Example 1. Thus, according to this embodiment, when layers containing AlN are stacked, the conversion efficiency can be dramatically improved.

[0041] In this embodiment, the thickness of the AlN-containing layer is not particularly limited and can be selected as appropriate. Furthermore, the AlN-containing layer does not necessarily have to be formed entirely on the lower electrode; a portion of the AlN-containing layer may be formed in areas where the lower electrode is not formed.

[0042] In the AlN layer formation process, by depositing an AlN-containing layer at a substrate temperature of 450°C or higher, the AlN-containing layer can be made into a layer capable of polarization reversal. While it's difficult to give a single definitive reason for this, the following are some possible explanations.

[0043] AlN exhibits a structural phase transition from high temperature to room temperature. In the high-temperature phase, it is cubic aluminum nitride, and in the low-temperature phase, it is hexagonal aluminum nitride. The high-temperature cubic aluminum nitride does not have piezoelectric properties, but the low-temperature hexagonal aluminum nitride does. When AlN is used as the piezoelectric material in a liquid discharge head, the AlN will act as the low-temperature hexagonal aluminum nitride. In hexagonal aluminum nitride, the crystallinity differs depending on the deposition temperature, and increasing the deposition temperature improves the crystallinity. Therefore, it is thought that when polarization treatment is performed, it becomes easier to obtain a layer containing AlN that can reverse polarization.

[0044] In AlN, the phase transition temperature between the high-temperature and low-temperature phases is approximately 500°C. However, since thin-film formation methods such as sputtering do not operate in thermal equilibrium, it can be said that a clear phase transition temperature does not exist. Therefore, considering improvements in piezoelectricity and thin-film formation methods, layers containing AlN are formed at temperatures above 450°C.

[0045] In this embodiment, the confirmation of whether polarization reversal is possible is performed as follows. An example will be given to illustrate this. The sample used for measurement consists of a lower electrode 111, an AlN-containing layer 112, and an upper electrode 113, with a protective film formed on the upper electrode 113. The protective film may be an insulating film. If the AlN-containing layer 112 consists of multiple layers, cross-finger electrodes 131 and 132 are used as electrodes for the sample. A voltage is applied through the lower electrode 111 and the upper electrode 113. The applied voltage is as follows: A triangular wave is generated using an arbitrary waveform generator, with a frequency of several Hz and an amplitude of ±10V, and this is amplified by an amplifier. A Trek 610C amplifier is used. In this device, the amplifier's amplification factor is 1,000 times, and when the signal generator outputs 10V, the output voltage becomes 10,000V. Assuming a sample film thickness of 1 μm, the electric field strength applied to the sample will be 100 MV / cm. This electric field strength value was calculated by dividing 10,000 V by 0.0001 cm. A voltage is applied to this sample, and the change in polarization value is measured. The change in polarization value due to the applied voltage is detected by a charge amplifier. Considering the method for determining the PE hysteresis curve of ferroelectric materials and the relationship Q=CV, the horizontal axis is used for voltage and the vertical axis is used for generated charge Q, and the plot is drawn with voltage on the horizontal axis and generated charge Q on the vertical axis. The generated charge Q on the vertical axis is output by the charge amplifier after it has been converted to voltage. In such a plot (also called a QV plot), the slope is C [F]. Here, since C is constant in the layer containing AlN, the QV plot becomes a straight line passing through the origin.

[0046] Figure 7 shows an example of the configuration of the above-described measuring device. In this configuration, measurements are performed using an arbitrary waveform generator, an amplifier, an inverting amplifier integrator, and a recorder. Channel 1 detects the output of the arbitrary waveform generator, and channel 2 detects the output of the inverting amplifier integrator. The QV plot is created based on the values ​​recorded by the recorder.

[0047] Layers containing AlN can be either polarimetrically reversible or non-polarimetrically reversible, depending on the material composition, crystal structure, and fabrication conditions. When polarization is reversible, applying an electric field opposite to the direction of polarization changes the direction of polarization (the direction of the polarization vector) so that it coincides with the direction of the electric field. This change in the direction of polarization when an electric field opposite to the direction of polarization is applied is called polarization reversal. In the case of a layer where polarization reversal is possible, the QV plot shows a discontinuously increasing relationship rather than a straight line Q=CV.

[0048] Furthermore, in the above measurement, an alternating electric field (triangular wave) is applied, so when the phase advances by 90°, an electric field in the opposite direction to the inverted polarization is applied. In this case, the polarization reverses when a certain tolerance value is exceeded. As a result, the measured value of ch2 shows a polarization response that resembles a square or rectangle. Furthermore, in some cases, the piezoelectric material may undergo dielectric breakdown before polarization reversal due to an increase in electric field strength, and such materials are unsuitable for this invention.

[0049] Figures 8A and 8B illustrate AlN that cannot undergo polarization reversal and AlN that can undergo polarization reversal. Figure 8A illustrates the case of AlN that cannot undergo polarization reversal and shows the results obtained using the example configuration of the measurement device in Figure 7. Figure 8B illustrates the case of AlN that can undergo polarization reversal and shows the results obtained using the example configuration of the measurement device in Figure 7.

[0050] Figure 8A(a) is a plot of the recorder's channels 1 and 2, with the horizontal axis representing time [seconds]. Since an alternating electric field (triangular wave) is applied, channel 1 is a triangular wave. As shown in the figure, the time evolution is the same for channel 1 (upper panel of Figure 8A(a)) and channel 2 (lower panel of Figure 8A(a)). In this case, as can be seen from the QV plot shown in Figure 8A(b), polarization reversal is not possible. As shown in Figure 8A(b), the QV plot is a straight line Q=CV, indicating that polarization reversal is not possible.

[0051] Similar to FIG. 8A(a), FIG. 8B(a) is a diagram plotting detected values of channel 1 and channel 2 of a recorder, and FIG. 8B(b) is a Q-V plot. As shown in FIG. 8B(a), in the case of AlN capable of polarization inversion, when an alternating electric field (triangular wave) is applied like the signal on channel 1, the measured value on channel 2 differs from that on channel 1 and changes stepwise. This indicates that polarization is inverted when the electric field exceeds a certain tolerance. In this case, the Q-V plot of FIG. 8B(b) does not form a straight line of Q=CV, but exhibits hysteresis. As described above, FIG. 8B shows that polarization inversion occurs, and it can be seen that the sample in FIG. 8B is capable of polarization inversion.

[0052] A supplementary description of polarization inversion will be given. In the Q-V plot of FIG. 8B(b), Ec and Ps are illustrated. Ec is also referred to as coercive electric field, and is the electric field intensity when the channel 2 signal intersects the horizontal axis. Ps is also referred to as spontaneous polarization, and is a polarization value when the channel 2 signal intersects the vertical axis. As described above, in the case of a sample capable of polarization inversion, Ec and Ps exist. On the other hand, as shown in FIG. 8A(b), in the case of a sample incapable of polarization inversion, Ec and Ps do not exist. Therefore, by checking the presence or absence of Ec and Ps, it can be confirmed whether polarization inversion is possible (whether polarization inversion occurs).

[0053] In the present embodiment, the layer containing AlN has a composition represented by the following formula (1) in which part of Al in AlN is substituted with Sc, or has a composition represented by the following formula (2) in which part of Al in AlN is substituted with Mg and a tetravalent element. Al 1-x Sc x N Formula (1) Al 1-x (Mg,β) x N Formula (2) Provided that in formula (1) and formula (2), x satisfies 0<x<1, and in formula (2), β represents a tetravalent element.

[0054] By substituting the layer containing AlN as described above, piezoelectric performance can be improved, and favorable ejection performance can be obtained. On the other hand, when the layer containing AlN is not substituted as described above, the layer cannot be made polarizable inversion, favorable piezoelectric performance cannot be obtained, and it is difficult to obtain favorable ejection performance. For example, even when the film formation temperature is set to 450° C. or higher, if the substitution is not performed as described above, the layer cannot be made capable of polarization inversion.

[0055] Piezoelectric materials in which Al in AlN is substituted with, for example, Sc are known. Considering the ionic radius and valence of Sc, it is suitable for use as a substituting element for AlN. A material obtained by substituting Sc in AlN has three times the piezoelectric performance of AlN within a certain composition range. Since the coercive electric field of this composition decreases, it is considered that polarization inversion treatment can be performed before dielectric breakdown occurs.

[0056] When a material obtained by substituting Sc in AlN is represented by a chemical formula, as shown in the above formula (1), Al 1-x Sc x N, where x represents the substitution amount of Sc, and 0 < x < 1. One of the crystal structures of AlN is hexagonal crystal. When substituted with Sc, as the substitution amount x increases, the c-axis of the hexagonal crystal shortens and the a-axis increases. An indicator of the ease of polarization is, for example, the axial ratio c / a. It can be said that the closer the axial ratio c / a is to 1, the easier polarization is.

[0057] From the above, in formula (1), x preferably satisfies 0.05 < x < 0.43, and more preferably satisfies 0.05 ≦ x ≦ 0.40. In this case, the axial ratio approaches 1, facilitating polarization. For example, when x = 0.25, the characteristics of the piezoelectric material can be improved to about 2.5 times that of d33 of unsubstituted AlN. Further, when x = 0.25, the relative dielectric constant becomes about 15, which can be improved 1.5 times compared with unsubstituted AlN.

[0058] Further, as a candidate for a substituting element for AlN other than Sc, trivalent elements can be mentioned. Examples of the trivalent element include boron, bismuth, lanthanoid elements, gallium, indium and the like, but the present inventor considered the concept of composite valence, and contemplated that a combination of a divalent element and a tetravalent element may also be used as a substituting element other than Sc.

[0059] Specifically, the inventor contemplated that Mg may be used as the divalent element, Ti, Zr, Hf, and Si may be used as the tetravalent element, and the divalent element and the tetravalent element may be used in combination. When this is expressed by a general formula, as shown in the above formula (2), Al 1-x (Mg,β) x N is obtained. When Sc is used as in the above formula (1), high cost is expected. Therefore, when the layer containing AlN has a composition represented by the above formula (2), the production cost can be reduced.

[0060] In formula (2), x preferably satisfies 0.05<x<0.43, and more preferably satisfies 0.05≦x≦0.40. Similar to the above formula (1), in this case, the axial ratio approaches 1, and polarization is facilitated.

[0061] In formula (2), the tetravalent element (β) is preferably selected from Ti, Zr, Hf and Si. In this case, β pairs as a charge compensating element for Mg, and the piezoelectric performance is improved.

[0062] In the present embodiment, the composition of the layer containing AlN is obtained using X-ray fluorescence analysis.

[0063] Here, the crystal structure of AlN will be described with reference to the drawings. FIG. 9 is a diagram schematically showing a unit cell of hexagonal aluminum nitride, in which part of Al and N are illustrated. A part of the illustrated Al is substituted with Sc, Mg, Ti or the like.

[0064] Figure 10 is a schematic diagram of a hexagonal aluminum nitride in which some of the Al is replaced by Mg and Zr. Figure 10 shows a lattice that is wider than the lattice in Figure 9. In the figure, one Mg and one Zr are shown, representing an example of the crystal structure of an AlN film substituted with Mg and a tetravalent element (in this case, Zr). Such a structure may also be called a MgZr-substituted AlN crystal.

[0065] There are no limitations on how AlN films with such a structure can be fabricated, but for example, they can be formed by arranging multiple Zr metal chips on a Mg cathode and using a simultaneous reactive sputtering method with the Al cathode. In such a method, various compositional films can be formed by using Ti, Hf, or Si instead of Zr metal chips.

[0066] In this embodiment, the layer containing AlN may be a single layer or multiple layers. When the layer containing AlN is multiple layers, for example, as shown in Figures 6(b) and (c), it is preferable that the electrodes include cross-finger electrodes and that the layers containing AlN are laminated via the cross-finger electrodes. By laminating the layers via electrodes in this way, an excellent effect can be obtained in which the conversion efficiency can be dramatically improved.

[0067] When using cross-finger electrodes, the terminology for the electrodes can be changed as appropriate. They may simply be called the first cross-finger electrode, the second cross-finger electrode, the GND electrode, the opposing electrode, the lower electrode, the upper electrode, etc.

[0068] In this embodiment, since the polarization of the AlN-containing layer can be reversed, when AlN-containing layers are stacked, it is possible to prevent the piezoelectric strain between the AlN-containing layers from canceling each other out, and thus reduce the driving voltage. For example, suppose that when the AlN-containing layer is a single layer, a displacement x is obtained with a driving voltage of 300V. In this embodiment, by using two layers of AlN-containing material and forming electrodes between the layers, a displacement x can be obtained with a driving voltage of approximately 150V. Furthermore, when a driving voltage of 300V is applied, a displacement of 2x can be obtained.

[0069] When there are multiple layers containing AlN, the number of layers n is not particularly limited and can be selected as appropriate. By increasing the number of layers n, the driving voltage can be reduced to 1 / n of the voltage when there is only one layer. For example, in a material configuration where 300V was applied to a single piezoelectric layer, if four piezoelectric layers are used in a cross-finger configuration, the same strain can be obtained by applying 75V to each piezoelectric layer. Therefore, if the driving voltage remains the same as for a single layer (300V) and four piezoelectric layers are used in a cross-finger configuration, the generated force will be four times greater.

[0070] If there are multiple layers containing AlN, the material composition, thickness, etc., may be the same or different from one layer to the other.

[0071] Next, this embodiment will be further described from the viewpoint of a method for manufacturing a liquid dispensing head. As described above, in the AlN layer formation process of this embodiment, the layer containing AlN is formed at 450°C or higher. Preferably, the formation temperature (film formation temperature, substrate temperature) is between 450°C and 800°C. When the temperature is within this range, the quality can be improved when forming the liquid discharge head in which the Si substrate and drive circuit are integrally formed. Furthermore, by keeping the temperature below 800°C, drift of the Vth of the MOS-Tr can be suppressed, reducing the possibility of interference with logic operation.

[0072] Furthermore, the upper limit of the formation temperature in the AlN layer formation process is more preferably 700°C or less, and even more preferably less than 600°C. In this case, the piezoelectric performance can be improved.

[0073] In this embodiment, a transistor metallization process may be performed. Although not particularly limited, if the temperature at which the AlN-containing layer is formed is 500°C or higher and 800°C or lower, it is preferable to perform the transistor metallization process after the AlN layer formation process. If the temperature is 500°C or lower, there are no particular limitations, and the AlN layer formation process may be performed after the transistor metallization process.

[0074] There are no particular limitations on the method for substituting some of the Al in the AlN layer with other elements, but examples include appropriately changing the fabrication conditions, such as appropriately changing the conditions of the magnetron sputtering method.

[0075] An example of conditions for forming a layer containing AlN in which some of the Al is replaced with Sc is shown below. By depositing a film under these conditions for several hours, for example, an Al layer with a thickness of 1 μm can be formed. (1-x) Sc x N film can be obtained. Fabrication method: Dual-stage simultaneous reactive magnetron sputtering method Substrate temperature: Room temperature to 700℃ Nitrogen concentration: 40% (argon balance) Target dimensions: 4 inches Al cathode power: 800W Sc cathode power: 0-800W The phrase "room temperature to 700°C" above means that the film will be deposited at any substrate temperature within the range of room temperature to 700°C. For example, "room temperature" means that the film will be deposited without heating the substrate.

[0076] When the AlN layer consists of multiple layers, the AlN layer formation process involves stacking the multiple AlN layers via cross-finger electrodes. For example, the layer configuration can be as shown in Figures 6(b) and (c). In this embodiment, by using multiple layers containing AlN, the conversion efficiency is improved, and good displacement can be obtained even when the driving voltage is reduced.

[0077] In the manufacturing method of the liquid discharge head of this embodiment, electrode films 113, 131, and 132 in Figure 6 are formed, followed by the formation of a protective film (not shown in Figure 6), and then a polling (polarization) process is performed to reverse the polarization of the AlN-containing layer. The polling process is performed after the formation of the AlN-containing layer, followed by the formation of the electrode, and then the formation of the protective film (not shown in Figure 6). If there are multiple layers containing AlN, the polling process is performed after all layers are formed and then the electrode is formed.

[0078] The polling process is not particularly limited and can be selected as appropriate. Among these, AC polling is preferred, and pulsed AC polling is more preferred. The AlN after the piezoelectric formation process is thought to be in a mixed state of hexagonal and cubic crystals, and in such a mixed state, pulsed AC polling is particularly preferred and yields good results.

[0079] An example of pulsed AC polling will be described. After the piezoelectric material formation process, double pulse measurements are performed for polarization reversal and non-reversal. The difference between the reversed and non-reversed charges is used to confirm whether polarization reversal has occurred. The pulse conditions are set to a slew rate of 600 V / μs, a holding time of 1 μs, and an amplitude of 600 V. The pulse is irradiated onto a sample with a thickness of 1 μm. In this way, polarization treatment can be performed on AlN.

[0080] Next, an example of how to manufacture the liquid dispensing head of this embodiment will be described. The example shown here assumes the formation of a liquid dispensing head as shown in Figure 2(b). Some components are omitted from this description.

[0081] (1) A CMOS logic unit (CMOS circuit) is formed on a silicon wafer (silicon substrate). When forming a CMOS circuit, a metallization process may be performed, or the metallization process may be performed after step (2) below. Depending on the temperature at which the AlN-containing layer is formed, it is preferable to perform the metallization process after step (2) below (step (4) below). Here, an example in which the metallization process is performed after step (2) below will be described.

[0082] (2) A diaphragm, an AlN-containing layer, and electrodes are formed on a silicon wafer. These can be formed using MEMS (Micro Electro Mechanical Systems) technology. An example is shown below. The diaphragm can be formed, for example, by depositing an SiO2 film or the like using plasma CVD (chemical vapor deposition). The lower electrode can be formed, for example, by depositing a film of Mo metal or the like using a DC magnetron sputtering method. For the layer containing AlN, for example, RF-reactive magnetron sputtering can be used. The upper electrode can be formed by depositing a film of Mo metal or the like using, for example, a DC magnetron sputtering method.

[0083] (3) Next, polarization processing is performed by pulse AC polling.

[0084] (4) Next, an interlayer insulating film (first insulating film) is formed to create contact holes. Then, metallization is performed to form extraction electrodes (lead-out wiring). For example, Al is used in the metallization process.

[0085] (5) Next, a passivation film (second insulating film) is removed and formed on the electrode.

[0086] (6) Next, a nozzle (nozzle hole) is formed, for example, by etching.

[0087] (7) Next, the silicon substrate is partially removed from the side opposite to the side on which the nozzle was formed to form a liquid chamber. For example, etching is used.

[0088] Through the above process, a liquid dispensing head as shown in Figure 2(b) can be formed.

[0089] In this embodiment of the liquid ejection head, an ink supply path can be created by joining a closure plate to the nozzle plate, which is effective in reducing manufacturing costs. For example, in a liquid ejection head in which a piezoelectric element is not provided on the nozzle plate, multiple parts necessary to form the liquid introduction path, such as a liquid resistance section, may be required. However, in this embodiment, the number of parts can be reduced, thereby reducing manufacturing costs.

[0090] Next, an example of a liquid dispensing apparatus according to the present invention will be described with reference to Figures 11 and 12. Figure 11 is a plan view illustrating the main part of the apparatus, and Figure 12 is a side view illustrating the main part of the apparatus.

[0091] This device is a serial type device, and the carriage 403 reciprocates in the main scanning direction by the main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is stretched across the left and right side plates 491A and 491B and holds the carriage 403 in a movable position. The carriage 403 is then reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 stretched between the drive pulley 406 and the driven pulley 407.

[0092] The carriage 403 is equipped with a liquid discharge unit 440 that integrates a liquid discharge head 1 and a head tank 441 according to the present invention. The liquid discharge head 1 of the liquid discharge unit 440 discharges liquids of various colors, such as yellow (Y), cyan (C), magenta (M), and black (K). The liquid discharge head 1 is mounted with a nozzle row consisting of multiple nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and with the discharge direction facing downward.

[0093] A supply mechanism 494 for supplying liquid stored outside the liquid discharge head 1 to the liquid discharge head 1 supplies the head tank 441 with liquid stored in the liquid cartridge 450.

[0094] The supply mechanism 494 consists of a cartridge holder 451, which is a filling section for mounting the liquid cartridge 450, a tube 456, a liquid delivery unit 452 including a liquid delivery pump, and the like. The liquid cartridge 450 is detachably mounted in the cartridge holder 451. Liquid is delivered from the liquid cartridge 450 to the head tank 441 via the tube 456 by the liquid delivery unit 452.

[0095] This device includes a transport mechanism 495 for transporting paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

[0096] The conveyor belt 412 attracts the paper 410 and transports it to a position opposite the liquid discharge head 1. This conveyor belt 412 is an endless belt and is stretched between the conveyor roller 413 and the tension roller 414. Attraction can be performed by electrostatic attraction or air suction.

[0097] Then, the conveyor belt 412 moves in a circular motion in the sub-scanning direction as the conveyor rollers 413 are rotationally driven by the sub-scanning motor 416 via the timing belt 417 and timing pulley 418.

[0098] Furthermore, a maintenance and recovery mechanism 420 for maintaining and recovering the liquid discharge head 1 is positioned on one side of the carriage 403 in the main scanning direction, next to the conveyor belt 412.

[0099] The maintenance and recovery mechanism 420 consists of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 1, and a wiper member 422 that wipes the nozzle surface.

[0100] The main scanning movement mechanism 493, the supply mechanism 494, the maintenance and recovery mechanism 420, and the transport mechanism 495 are mounted on a housing that includes side plates 491A, 491B, and a back plate 491C.

[0101] In this configured device, the paper 410 is fed onto the transport belt 412 and picked up, and the paper 410 is transported in the sub-scanning direction by the circumferential movement of the transport belt 412.

[0102] Therefore, by moving the carriage 403 in the main scanning direction and driving the liquid ejection head 1 in accordance with the image signal, liquid is ejected onto the stationary paper 410 to form an image.

[0103] Thus, since this device is equipped with a liquid discharge head according to the present invention, it can stably form high-resolution images.

[0104] Next, another example of the liquid dispensing unit according to the present invention will be described with reference to Figure 13. Figure 13 is a plan view illustrating the main parts of the unit.

[0105] This liquid discharge unit consists of a housing portion comprising side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid discharge head 1, which are components of the device that discharges the liquid.

[0106] Furthermore, a liquid dispensing unit can also be configured by further attaching, for example, the side plate 491B of this liquid dispensing unit to at least one of the aforementioned maintenance and recovery mechanism 420 and supply mechanism 494.

[0107] Next, yet another example of the liquid dispensing unit according to the present invention will be described with reference to Figure 14. Figure 14 is a front view of the unit.

[0108] This liquid discharge unit consists of a liquid discharge head 1 to which a flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

[0109] The flow path component 444 is located inside the cover 442. A head tank 441 can be included instead of the flow path component 444. Furthermore, a connector 443 for electrical connection to the liquid discharge head 1 is provided on the upper part of the flow path component 444.

[0110] In this application, the discharged liquid is not particularly limited as long as it has a viscosity and surface tension that can be discharged from the head, but it is preferable that its viscosity becomes 30 mPa·s or less at room temperature and atmospheric pressure, or when heated or cooled. More specifically, it is a solution, suspension, emulsion, etc. containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a polymerizable compound, a resin, a functional material such as a surfactant, a biocompatible material such as DNA, amino acids or proteins, calcium, or an edible material such as a natural pigment. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic elements and light-emitting elements or electronic circuit resist patterns, and material liquids for 3D molding.

[0111] A "liquid discharge unit" includes a combination of a liquid discharge head and at least one of the following components: a head tank, carriage, supply mechanism, maintenance and recovery mechanism, and main scanning and moving mechanism.

[0112] Here, integration includes, for example, cases where the liquid dispensing head and functional components or mechanisms are fixed to each other by fastening, bonding, engaging, etc., or where one is held movably relative to the other. Furthermore, the liquid dispensing head and functional components or mechanisms may be configured to be detachable from each other.

[0113] For example, some liquid dispensing units have a liquid dispensing head and head tank integrated into one unit. Others have a liquid dispensing head and head tank integrated into one unit, connected to each other by tubes or similar means. In these liquid dispensing units, a unit including a filter can also be added between the head tank and the liquid dispensing head.

[0114] Additionally, some liquid dispensing units have an integrated liquid dispensing head and carriage.

[0115] Furthermore, some liquid dispensing units integrate the liquid dispensing head and the scanning mechanism by movably holding the liquid dispensing head in a guide member that constitutes part of the scanning mechanism. Others integrate the liquid dispensing head, carriage, and main scanning mechanism.

[0116] Furthermore, some liquid dispensing units integrate the liquid dispensing head, carriage, and maintenance / recovery mechanism by fixing a cap component, which is part of the maintenance / recovery mechanism, to a carriage to which the liquid dispensing head is attached.

[0117] Furthermore, some liquid discharge units have a head tank or a liquid discharge head to which flow path components are attached, to which a tube is connected, integrating the liquid discharge head and the supply mechanism. Through this tube, the liquid from the liquid storage source is supplied to the liquid discharge head.

[0118] The main scanning movement mechanism shall include the guide member alone. The supply mechanism shall also include the tube alone and the loading section alone.

[0119] "A device for dispensing liquid" includes devices that have a liquid dispensing head or liquid dispensing unit and drive the liquid dispensing head to dispense liquid. A device for dispensing liquid includes not only devices that can dispense liquid onto surfaces to which liquid can adhere, but also devices that dispense liquid into air or into liquid.

[0120] This "liquid dispensing device" may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc.

[0121] For example, "devices that dispense liquids" include image forming machines, which dispense ink to form images on paper, and three-dimensional molding machines, which dispense molding liquid into a powder layer formed in layers to create three-dimensional objects.

[0122] Furthermore, "devices that dispense liquid" are not limited to those that visualize meaningful images such as letters or figures through the dispensed liquid. For example, devices that form patterns that do not have meaning in themselves, or devices that create three-dimensional images, are also included.

[0123] The term "materials to which liquid can adhere" above refers to materials to which liquid can adhere, at least temporarily, including materials that adhere and solidify, or materials that adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0124] The materials referred to as "materials to which liquid can adhere" above include paper, thread, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere to them, even temporarily.

[0125] Furthermore, "liquid dispensing devices" include devices in which the liquid dispensing head and the surface to which the liquid can adhere move relative to each other, but are not limited to these. Specific examples include serial-type devices in which the liquid dispensing head moves, and line-type devices in which the liquid dispensing head does not move.

[0126] Other examples of "devices that dispense liquids" include processing liquid coating devices that dispense processing liquid onto the surface of paper for purposes such as modifying the surface of the paper, and injection granulation devices that granulate fine particles of raw materials by spraying a compositional solution, in which raw materials are dispersed in a solution, through a nozzle.

[0127] In this application, the terms image formation, recording, printing, copying, printing, and shaping are all considered synonymous. [Examples]

[0128] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0129] (Example 1 and Comparative Example 1: When the layer containing AlN is a single layer) A thin film component was formed on a silicon substrate by depositing an SiO2 film using plasma CVD. Next, a Mo metal film was deposited using DC magnetron sputtering to form a lower electrode. Then, a layer containing AlN was formed under the following conditions.

[0130] [Conditions for forming layers containing AlN] Method: Dual-stage simultaneous reactive magnetron sputtering Substrate temperature and heating time: The temperature was increased from room temperature and heated to the temperatures shown in Table 1 below. Nitrogen concentration: 40% (argon balance) Target dimensions: 4 inches Al cathode power: 800W Sc cathode power: 0-800W

[0131] As described above, a layer containing AlN with a thickness of 1 μm was formed over several hours. Here, there was one layer containing AlN, and the composition of the formed AlN-containing layer was Al 1-x Sc x It is N.

[0132] Next, a Mo metal film was deposited using DC magnetron sputtering to form the upper electrode. Next, pulsed AC polling was performed to polarize the formed AlN-containing layer. The pulse conditions were a slew rate of 600 V / μs, a holding time of 1 μs, and an amplitude of 600 V. The pulse was irradiated onto a 1 μm thick sample. In this way, the AlN was polarized.

[0133] Polarization reversal was confirmed using the measurement apparatus configuration shown in Figure 7. The presence or absence of Ec and Ps was also confirmed in the QV plot. Furthermore, piezoelectricity (d33) was measured using a known measurement method.

[0134] Based on the above, the film deposition temperature (substrate temperature), substitution element, and substitution amount were changed as shown in Table 1 below. The substitution amount (%) refers to Al 1-x Sc x N or Al 1-x (Mg,β) x This corresponds to x in N expressed as a percentage. The composition and substitution amount of the layer containing AlN were determined using X-ray fluorescence analysis.

[0135] [Table 1]

[0136] As can be seen from Table 1, polarization reversal is not possible when the film deposition temperature is below 450°C. In Comparative Examples 1-1 to 1-6, polarization reversal is marked with "×" in Table 1, indicating that dielectric breakdown occurred. Thus, in the comparative examples, dielectric breakdown occurred before polarization reversal could occur due to the increase in electric field strength, and polarization reversal was not possible. On the other hand, in Examples 1-1 to 1-14, the film deposition temperature was 450°C or higher, and polarization reversal was possible. In the measured QV plots, hysteresis as shown in Figure 8B(b) was observed, and Ec and Ps were present as shown in Table 1. Examples 1-13 and 1-14 are examples of forming an AlN-containing layer at high temperatures (600°C and 700°C). Although polarization reversal occurs, the d33 was slightly inferior to that of Example 1-6 due to the high deposition temperature, but this does not pose a practical problem. Furthermore, in Examples 1-2, 1-7, 1-9, and 1-11, where the substitution amount was 5% (x=0.05), although d33 was slightly inferior compared to the other examples, polarization reversal was possible and the result was at a practical level. Also, considering Examples 1-2 to 1-4, for example, a substitution amount of 10% or more (x≧0.10) is preferable, and 25% or more (x≧0.25) is more preferable.

[0137] (Example 2: When there are multiple layers containing AlN) <Example 2-1: Fabrication of a liquid dispensing head having multiple layers containing AlN> Here, we adopted the layer configuration shown in Figure 6(b). A thin film member 102 with a thickness of 5 μm was formed on a silicon substrate by depositing an SiO2 film using plasma CVD. Next, a Mo film with a thickness of 0.1 μm was deposited on the diaphragm to serve as the counter electrode (electrode 131) for the crossed finger electrodes. Next, a 40% Sc-substituted AlN film was deposited on the electrode 131 as layer 112b containing AlN, with a thickness of 0.5 μm. Next, a Mo film with a thickness of 0.1 μm was deposited on the AlN-containing layer 112b to serve as the GND electrode (electrode 132) of the crossed finger electrode. Next, a 40% Sc-substituted AlN film was deposited on the electrode 132 as layer 112c containing AlN, with a thickness of 0.5 μm. Next, a Mo film with a thickness of 0.1 μm was deposited on the AlN-containing layer 112c to serve as the counter electrode (electrode 131) for the crossed finger electrode. This Mo film was designed to be electrically conductive with the first Mo film. Next, the silicon substrate was partially removed from the back surface to form a liquid chamber 201. By forming the liquid chamber 201, a region was secured in which the thin film member 102 could be deformed.

[0138] Next, the sample temperature was heated to 200°C and AC pulse poling (polarization treatment) was performed. The AC pulse poling conditions were a slew rate of 600 V / μs, a holding time of 1 μs, and an amplitude of ±600 V, and one cycle of treatment was performed under these conditions.

[0139] In this manner, the liquid dispensing head of this embodiment was fabricated. However, since we did not evaluate the liquid dispensing performance here, the fabrication of the nozzle was omitted.

[0140] Next, when a drive voltage was applied to the liquid discharge head of this embodiment and the displacement was evaluated, a displacement was confirmed.

[0141] <Example 2-2: Fabrication of a liquid dispensing head with a single layer containing AlN> In Example 2-1, a liquid discharge head was formed in the same manner as in Example 2-1, except that the layer containing AlN was a single layer of 40%Sc-substituted AlN film with a thickness of 1 μm, and the electrodes were a lower electrode and an upper electrode. Displacement was also evaluated for this liquid discharge head, and displacement was confirmed.

[0142] <Example 2-3: Evaluation of Conversion Efficiency> Next, the conversion efficiency was evaluated as follows. First, a voltage of 300V was applied as the driving voltage to the liquid discharge head of Example 2-2 (single layer), and the amount of displacement was determined. The reason why a single-layer 40%Sc-substituted AlN film with a thickness of 1 μm is used as the AlN-containing layer in the liquid discharge head of Example 2-2 is for comparison with the AlN-containing layer in the liquid discharge head of Example 2-1, which consists of a 40%Sc-substituted AlN film with a thickness of 0.5 μm (AlN-containing layer 112b) and a 40%Sc-substituted AlN film with a thickness of 0.5 μm (AlN-containing layer 112c). On the other hand, when a drive voltage was applied to the liquid discharge head of Example 2-1, a displacement equivalent to that of Example 2-2 was observed when 150V was applied. Therefore, it can be seen that the liquid discharge head of Example 2-1 achieves an equivalent amount of displacement at a low voltage, demonstrating excellent conversion efficiency.

[0143] (Example 3: Fabrication of a liquid dispensing head and evaluation of dispensing performance) The liquid dispensing head of this embodiment was fabricated as follows, and its dispensing performance was evaluated.

[0144] <Example 3-1: When the layer containing AlN is a single layer> First, a thin film member 102 with a thickness of 5 μm was formed on a silicon substrate by depositing an SiO2 film using plasma CVD. Next, a Mo film with a thickness of 0.1 μm was deposited on the thin film member 102 as the lower electrode 111. Then, in the same manner as in Example 1-1, a single layer of 40% Sc-substituted AlN film with a thickness of 1 μm was formed as an AlN-containing layer. The deposition temperature was 450°C as shown in Table 1. Next, a Mo film with a thickness of 0.1 μm was deposited as the upper electrode 113. Next, the sample temperature was heated to 200°C, and AC pulse poling was performed to induce polarization.

[0145] Next, a nozzle 101 with a diameter of 10 μm was formed. Next, etching (Deep-RIE) was performed on the back surface of the silicon substrate to form a liquid chamber 201. Here, the liquid chamber 201 was formed so that the diameter of the fixed end of the thin film member 102 was 200 μm. In addition, the diameter of the drive portion (deformation region 121) of the thin film member 102 (corresponding to the diameter of the upper electrode) was set to 70% of the diameter of the vibration region of the thin film member 102. Next, an ink supply path was created by joining a blocking plate to the liquid chamber 201 side.

[0146] Furthermore, a film may be formed on the Si wall of the liquid chamber 201 to improve liquid contactability. Alternatively, the silicon substrate may be polished before fabricating the liquid chamber 201. For example, polishing to a thickness of approximately 400 μm can shorten the etching time.

[0147] Next, a protective film 119 was formed on the upper electrode 113 for electrical and mechanical protection. Alternatively, a liquid-contacting film that is hydrophobic to liquid droplets may be formed. In this way, the liquid dispensing head of this embodiment was manufactured.

[0148] Next, the liquid chamber was filled with Dawanol (viscosity 8 cP), and the droplet dispensing performance was evaluated by applying a drive voltage. The evaluation was performed as follows. When a liquid dispensing head maintained at a steady state of +150V was subjected to a -150V potential for 1 μs and then returned to +150V, 4 pl droplets were dispensed at a speed of 7 m / s. This demonstrated good dispensing performance.

[0149] Furthermore, in this embodiment, the liquid ejection head allows for the creation of an ink supply path by joining a blocking plate, which is effective in reducing manufacturing costs. For example, in a liquid ejection head where a piezoelectric element is not provided on the nozzle plate, multiple parts, such as a liquid resistance section, may be required to form the liquid introduction path. However, in this embodiment, the number of parts can be reduced, thereby lowering manufacturing costs.

[0150] <Comparative Example 3-1: When the layer containing AlN is a single layer> In Example 3-1 described above, a liquid dispensing head was manufactured in the same manner as in Example 3-1, except that the layer containing AlN was changed to one manufactured under the conditions of Comparative Example 1-6 (film deposition temperature of 400°C). When the liquid discharge head manufactured in this manner was evaluated for discharge performance in the same manner as in Example 3-1 above, it was found that a voltage of +300V to -300V was required to discharge 4 pl droplets at a speed of 7 m / s, and good discharge performance could not be obtained.

[0151] <Example 3-2: When there are multiple layers containing AlN> Next, the droplet dispensing performance of a liquid dispensing head in which the AlN-containing layer consists of multiple piezoelectric layers was similarly evaluated. In the above liquid dispensing head, two layers containing AlN were formed as in Example 2, and cross-finger electrodes were created. In this way, the liquid dispensing head of Example 3-2 was manufactured. The droplet discharge performance of this liquid discharge head was evaluated in the same manner as in Example 3-1. In this example, when applying the drive voltage, droplet discharge was possible at a lower drive voltage than in Example 3-1, just as in Example 3-1. Specifically, 4 pl droplets could be discharged at a speed of 7 m / s at a lower drive voltage than in Example 3-1. More precisely, the above discharge could be achieved at about half the drive voltage of Example 3-1, i.e., a drive voltage of about 75 V. Thus, according to this example, it was possible to achieve good discharge performance while further improving the conversion efficiency. [Explanation of Symbols]

[0152] 1. Liquid dispensing head 101 Nozzles 102 Thin film components 111 Lower electrode 112 AlN-containing layer 113 Upper electrode 201 Liquid chamber [Prior art documents] [Patent Documents]

[0153] [Patent Document 1] WO2011002028 publication [Patent Document 2] Special Publication No. 2019-530601 [Patent Document 3] Japanese Patent Publication No. 2021-112907 [Patent Document 4] Japanese Patent Publication No. 2013-219743 [Patent Document 5] WO2015080023 publication

Claims

1. A deformable thin film member having an opening, The thin film member comprises an electromechanical conversion element arranged around the opening of the thin film member and deforming the thin film member, The electromechanical conversion element includes an electrode and a layer containing AlN. The liquid dispensing head is characterized in that the layer containing AlN is capable of polarization reversal and has a composition represented by the following formula (1) in which some of the Al in AlN is replaced with Sc, or has a composition represented by the following formula (2) in which some of the Al in AlN is replaced with Mg and tetravalent elements. Al １－ｘ Sc ｘ N in Formula (1) Al １－ｘ (Mg, β) ｘ N in formula (2) However, in equation (1), x is 0 < x < 1, and in equation (2), x is 0.05 < x < 0.43, and β represents a tetravalent element.

2. A deformable thin film member having an opening, The thin film member comprises an electromechanical conversion element arranged around the opening of the thin film member and deforming the thin film member, The electromechanical conversion element includes an electrode and a layer containing AlN. The AlN-containing layer is capable of polarization reversal and has a composition represented by the following formula (1) in which some of the Al in the AlN is replaced with Sc, or has a composition represented by the following formula (2) in which some of the Al in the AlN is replaced with Mg and tetravalent elements. A liquid dispensing head characterized in that, when some of the Al in the AlN-containing layer is replaced with Mg and a tetravalent element, the tetravalent element is selected from Ti, Zr, Hf, and Si. Al １－ｘ Sc ｘ N in Formula (1) Al １－ｘ (Mg, β) ｘ N in formula (2) However, in equations (1) and (2), x is 0 < x < 1, and in equation (2), β represents a tetravalent element.

3. A deformable thin film member having an opening, The thin film member comprises an electromechanical conversion element arranged around the opening of the thin film member and deforming the thin film member, The electromechanical conversion element includes an electrode and a layer containing AlN. The electrodes include crossed finger electrodes, The liquid dispensing head is characterized in that the layer containing AlN is capable of polarization reversal, has a composition represented by the following formula (1) with some of the Al in AlN replaced by Sc, or has a composition represented by the following formula (2) with some of the Al in AlN replaced by Mg and tetravalent elements, and consists of multiple layers stacked via the cross-finger electrodes. Al １－ｘ Sc ｘ N in Formula (1) Al １－ｘ (Mg, β) ｘ N in formula (2) However, in equations (1) and (2), x is 0 < x < 1, and in equation (2), β represents a tetravalent element.

4. The liquid dispensing head according to claim 2 or 3, characterized in that in formula (2), x is 0.05 < x < 0.

43.

5. The liquid dispensing head according to claim 1 or 3, characterized in that the tetravalent element is selected from Ti, Zr, Hf, and Si.

6. The electrodes include crossed finger electrodes, The liquid dispensing head according to claim 1 or 2, characterized in that the layer containing AlN consists of a plurality of layers and is laminated via the cross-finger electrodes.

7. The liquid dispensing head according to any one of claims 1 to 6, characterized in that in formula (1), x is 0.05 < x < 0.

43.

8. A liquid dispensing unit characterized by comprising a liquid dispensing head according to any one of claims 1 to 7.

9. The liquid discharge unit according to claim 8, characterized in that the liquid discharge head is integrated with at least one of the following: a head tank for storing liquid to be supplied to the liquid discharge head; a carriage on which the liquid discharge head is mounted; a supply mechanism for supplying liquid to the liquid discharge head; a maintenance and recovery mechanism for maintaining and restoring the liquid discharge head; and a main scanning movement mechanism for moving the liquid discharge head in the main scanning direction.

10. A liquid dispensing device characterized by comprising a liquid dispensing head according to any one of claims 1 to 7, or a liquid dispensing unit according to claim 8 or 9.

11. A method for manufacturing a liquid dispensing head comprising a deformable thin film member having an opening, and an electromechanical conversion element disposed around the opening of the thin film member for deforming the thin film member, The electromechanical conversion element includes an electrode and a layer containing AlN. An AlN layer formation step in which the AlN-containing layer is formed at 450°C or higher, The process includes a polarization treatment step for polarizing the layer containing AlN, A method for manufacturing a liquid dispensing head, characterized in that the layer containing AlN has a composition represented by the following formula (1) in which some of the Al in AlN is replaced with Sc, or has a composition represented by the following formula (2) in which some of the Al in AlN is replaced with Mg and a tetravalent element. Al １－ｘ Sc ｘ N in Formula (1) Al １－ｘ (Mg, β) ｘ N Formula (2) However, in equation (1), x is 0 < x < 1, and in equation (2), x is 0.05 < x < 0.43, and β represents a tetravalent element.

12. A method for manufacturing a liquid dispensing head comprising a deformable thin film member having an opening, and an electromechanical conversion element disposed around the opening of the thin film member for deforming the thin film member, The electromechanical conversion element includes an electrode and a layer containing AlN. An AlN layer formation step in which the AlN-containing layer is formed at 450°C or higher, The process includes a polarization treatment step for polarizing the layer containing AlN, The AlN-containing layer has a composition represented by the following formula (1) in which some of the Al in the AlN is replaced with Sc, or has a composition represented by the following formula (2) in which some of the Al in the AlN is replaced with Mg and tetravalent elements. A method for manufacturing a liquid dispensing head, characterized in that, when some of the Al in the AlN-containing layer is replaced with Mg and a tetravalent element, the tetravalent element is selected from Ti, Zr, Hf, and Si. Al １－ｘ Sc ｘ N Formula (1) Al １－ｘ (Mg, β) ｘ N in formula (2) However, in equations (1) and (2), x is 0 < x < 1, and in equation (2), β represents a tetravalent element.

13. A method for manufacturing a liquid dispensing head comprising a deformable thin film member having an opening, and an electromechanical conversion element disposed around the opening of the thin film member for deforming the thin film member, The electromechanical conversion element includes an electrode and a layer containing AlN. An AlN layer formation step in which the AlN-containing layer is formed at 450°C or higher, The process includes a polarization treatment step for polarizing the layer containing AlN, The AlN-containing layer has a composition represented by the following formula (1) in which some of the Al in the AlN is replaced with Sc, or has a composition represented by the following formula (2) in which some of the Al in the AlN is replaced with Mg and tetravalent elements. The electrodes include crossed finger electrodes, The method for manufacturing a liquid dispensing head is characterized in that the AlN layer formation step involves stacking a plurality of layers containing AlN via the crossed finger electrodes. Al １－ｘ Sc ｘ N in formula (1) Al １－ｘ (Mg, β) ｘ N Formula (2) However, in equations (1) and (2), x is 0 < x < 1, and in equation (2), β represents a tetravalent element.

14. The method for manufacturing a liquid dispensing head according to any one of claims 11 to 13, characterized in that the AlN layer formation step is to form the layer containing AlN at a temperature of 450°C or higher and 800°C or lower.

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