JP2008060520A - Method of manufacturing dielectric film, method of manufacturing piezoelectric element, and infrared heating unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a dielectric film, which can form a dielectric film having: excellent crystallinity; a method of manufacturing a piezoelectric element; and an infrared heating unit. <P>SOLUTION: A method of manufacturing a dielectric film comprises: a process of applying a sol of an organic metal compound to one side of a substrate 110 so as to form a dielectric precursor film 71; and a process of applying infrared irradiation, which has a wavelength range excluding a wavelength region for which the dielectric precursor film 71 has high absorptance, to an area of the substrate 110, which is opposite to the dielectric precursor film 71, and of applying infrared irradiation to the other side of the substrate 110 so as to heat and bake the dielectric precursor film 71 for crystallizing it. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a dielectric film, a method for manufacturing a piezoelectric element, and an infrared heating apparatus used for manufacturing the dielectric film, and in particular, a method for manufacturing a dielectric film used for a liquid jet head and a method for manufacturing a piezoelectric element. In addition, the present invention relates to an infrared heating device used in manufacturing these.

  A piezoelectric element used for a liquid ejecting head or the like is an element in which a dielectric film made of a piezoelectric material exhibiting an electromechanical conversion function is sandwiched between two electrodes. The dielectric film is made of, for example, crystallized piezoelectric ceramics. Has been.

  As a liquid ejecting head using such a piezoelectric element, for example, a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is constituted by a vibration plate, and the vibration plate is deformed by the piezoelectric element and pressure is applied. There is an ink jet recording head that pressurizes ink in a generation chamber and ejects ink droplets from nozzle openings. Two types of ink jet recording heads have been put into practical use: those using a longitudinal vibration mode piezoelectric actuator that extends and contracts in the axial direction of the piezoelectric element, and those using a flexural vibration mode piezoelectric actuator. As an example of using a flexural vibration mode actuator, for example, a piezoelectric layer made of a uniform dielectric film is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric layer is subjected to pressure by a lithography method. A known piezoelectric element is formed so as to be independent for each pressure generating chamber by cutting into a shape corresponding to the generating chamber.

  A so-called sol-gel method is known as a method for manufacturing a piezoelectric layer constituting a piezoelectric element. That is, a step of applying a sol of an organometallic compound on a substrate on which a lower electrode is formed, drying and gelling (degreasing) to form a precursor film of a piezoelectric layer is performed at least once, and then a high temperature And heat treatment to crystallize. A piezoelectric layer (piezoelectric thin film) having a predetermined thickness is manufactured by repeating these steps a plurality of times.

  A so-called MOD (Metal-Organic Decomposition) method is known as a method for manufacturing a piezoelectric layer (dielectric film) constituting a piezoelectric element. That is, generally, a colloidal solution obtained by dissolving an organometallic compound such as a metal alkoxide in alcohol and adding a hydrolysis inhibitor or the like to this is applied onto an object, and then dried and fired. Is formed.

  In addition, in the sol-gel method, the MOD method, and the like, an infrared heating apparatus that heats by irradiating infrared rays is used when a dielectric precursor film is heated and fired to be crystallized to form a dielectric film. Has been.

  When an infrared heating device is used, a desired temperature rise rate cannot be obtained simply by irradiating infrared rays from one side of the front surface or back surface of the substrate provided with the dielectric precursor film on one side, and an excellent crystal A dielectric film cannot be formed. For this reason, the dielectric precursor film was heated and fired at a desired temperature increase rate by irradiating infrared rays from both the front surface and the back surface of the substrate.

  However, most of the infrared rays irradiated to the dielectric precursor film from the dielectric precursor film side of the substrate is absorbed by the dielectric precursor film, and heats the dielectric precursor film. For this reason, the starting point at which crystallization of the dielectric precursor film starts is on the surface side of the dielectric precursor film (on the side opposite to the base) or in the film of the dielectric precursor film, and the crystal is on the base side. While it grows independently without inheriting crystallinity such as orientation and crystal grain size, and a columnar crystal stands, a large crystal with independent crystal grains is formed, and crystallinity such as displacement characteristics There is a problem that a poor dielectric film is formed.

  In addition, a method for manufacturing a piezoelectric element that irradiates infrared rays including a wavelength of 3 μm to 5 μm from the substrate side when the sol is heated and degreased has been proposed (for example, see Patent Document 1).

  However, in Patent Document 1, only infrared light having a wavelength that is easily absorbed by the sol is used, and the wavelength of the infrared light is only defined in the degreasing step of the sol. Further, in Patent Document 1, there is a problem that infrared irradiation is performed only from the substrate side, the temperature rising rate cannot be increased, and a dielectric film having excellent crystal characteristics cannot be formed.

JP 2003-115619 A (Claims, page 5, FIG. 6)

  In view of such circumstances, an object of the present invention is to provide a dielectric film manufacturing method, a piezoelectric element manufacturing method, and an infrared heating apparatus capable of forming a dielectric film having excellent crystallinity.

An aspect of the present invention that solves the above-described problems is a process of forming a dielectric precursor film by applying a sol of an organometallic compound on one side of a substrate, and facing the dielectric precursor film of the substrate Irradiate infrared light in a wavelength region excluding a wavelength region having a high absorption rate of the dielectric precursor film from the region, and heat and bak the dielectric precursor film by irradiating infrared light from the other surface side of the substrate. And a step of crystallizing the dielectric film.
In such an embodiment, an excellent crystalline dielectric film can be formed. In other words, since the dielectric film itself can be heated without being heated by infrared rays, the thickness of the dielectric film is not limited and the formation of large crystals can be prevented. Thus, it can be formed with relatively small and uniform crystals. Further, by irradiating infrared rays from both sides of the substrate, the temperature rise rate can be increased and an excellent crystalline dielectric film can be formed.

  Here, the infrared irradiation of the wavelength region excluding the wavelength region where the absorption rate of the dielectric precursor film is high excludes the heat source that irradiates the infrared ray and the wavelength region where the absorption rate of the dielectric precursor film is high. It is preferable to use a filter. According to this, it is possible to easily irradiate infrared rays in a desired wavelength region, and it is possible to reliably heat and crystallize the base of the dielectric film without heating the dielectric film itself.

  Moreover, it is preferable to further comprise a drying step of drying the dielectric precursor film and a degreasing step of degreasing the dried dielectric precursor film before the step of crystallizing the dielectric precursor film. According to this, the dielectric film excellent in crystallinity can be obtained by performing a drying process and a degreasing process.

  The step of crystallizing the dielectric precursor film by heating and firing is preferably performed at a temperature rising rate of 100 ° C./sec or more. According to this, an excellent crystalline dielectric film can be formed by firing at a high temperature rising rate.

Furthermore, another aspect of the present invention includes a step of forming a lower electrode on the substrate, a step of forming the piezoelectric layer on the lower electrode, and a step of forming an upper electrode on the piezoelectric layer. And the step of forming the piezoelectric layer is a method of manufacturing a dielectric film manufactured by the manufacturing method of the above aspect.
In such an embodiment, a piezoelectric element having a dielectric film having excellent crystallinity can be formed, so that a piezoelectric element having excellent displacement characteristics can be obtained.

  Here, the lower electrode has an adhesion layer on the substrate side, and in the step of crystallizing the dielectric precursor film by heating and baking, the color temperature for irradiating infrared rays from the other surface side of the substrate is set as follows. It is preferable to carry out by making it lower than the color temperature of the heat source which irradiates infrared rays from the one surface side of the substrate. According to this, the temperature at which the substrate side is heated from the adhesion layer is set lower than the temperature at which the piezoelectric layer side is heated from the adhesion layer, so that the piezoelectric layer side to the substrate side with the adhesion layer interposed therebetween. A temperature gradient that decreases toward the bottom can be applied, and the adhesion layer can be prevented from diffusing into the lower electrode and the adhesion between the substrate and the lower electrode being reduced to cause the lower electrode to peel off.

  Moreover, it is preferable that the said adhesion layer consists of a material which has titanium as a main component. According to this, by using titanium as the adhesion layer, the adhesion force between the lower electrode and the substrate can be improved, and titanium can be prevented from diffusing into the lower electrode. It is possible to prevent the lower electrode from being peeled off due to the lowering of the adhesive force between the lower electrode and the lower electrode.

Furthermore, another aspect of the present invention is provided in a region opposite to the dielectric film side of the substrate provided with the dielectric precursor film on one surface side, and the absorption rate of the dielectric precursor film is increased. A first heating unit that irradiates infrared light in a wavelength region excluding a large wavelength region; and a second heating unit that is provided on the other surface side of the substrate and irradiates infrared light on the other surface side of the substrate. An infrared heating device is provided.
In such an embodiment, an excellent crystalline dielectric film can be formed by reliably heating the base of the dielectric film without heating the dielectric film itself by the infrared heating device.

  The first heating means includes a heat source that emits infrared rays, and a filter that is provided between the heat source and the substrate and excludes a wavelength region having a high absorption rate of the dielectric precursor film. It is preferable that According to this, it is possible to easily irradiate the dielectric film side with infrared rays in a desired wavelength region.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is an exploded perspective view showing a schematic configuration of an ink jet recording head which is an example of a liquid ejecting head according to Embodiment 1 of the present invention. FIG. 2 is a plan view of FIG. FIG.

  As shown in the drawing, 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 has a thickness of 0. An elastic film 50 of 5 to 2 μm is formed.

  In the flow path forming substrate 10, pressure generating chambers 12 partitioned by a plurality of partition walls 11 are arranged in parallel in the width direction (short direction) by anisotropic etching from the other surface side. In addition, an ink supply path 14 and a communication path 15 are partitioned by a partition wall 11 on one end side in the longitudinal direction of the pressure generating chamber 12 of the flow path forming substrate 10. In addition, a communication portion 13 constituting a part of the reservoir 100 serving as an ink chamber (liquid chamber) common to the pressure generation chambers 12 is formed at one end of the communication passage 15. That is, the flow path forming substrate 10 is provided with a liquid flow path including a pressure generation chamber 12, a communication portion 13, an ink supply path 14, and a communication path 15.

  The ink supply path 14 communicates with one end side in the longitudinal direction of the pressure generation chamber 12 and has a smaller cross-sectional area than the pressure generation chamber 12. For example, in the present embodiment, the ink supply path 14 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. As described above, in this embodiment, the ink supply path 14 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. Further, each communication path 15 communicates with the side of the ink supply path 14 opposite to the pressure generation chamber 12 and has a larger cross-sectional area than the width direction (short direction) of the ink supply path 14. In this embodiment, the communication passage 15 is formed with the same cross-sectional area as the pressure generation chamber 12.

  In other words, the flow path forming substrate 10 is connected to the pressure generation chamber 12, the ink supply path 14 having a smaller cross-sectional area in the short direction of the pressure generation chamber 12, the ink supply path 14, and the ink supply. A communication passage 15 having a cross-sectional area larger than the cross-sectional area in the short direction of the path 14 is provided by being partitioned by a plurality of partition walls 11.

  Further, 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 14 is provided with an adhesive. Or a heat-welded 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 made of silicon dioxide and 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. An insulator film 55 made of zirconium oxide (ZrO ₂ ) or the like and having a thickness of, for example, about 0.4 μm is laminated. On the insulator film 55, the lower electrode film 60 having a thickness of about 0.1 to 0.5 μm and lead zirconate titanate (PZT) which is an example of a dielectric film are formed. For example, a piezoelectric layer 70 having a thickness of about 1.1 μm and an upper electrode film 80 made of gold, platinum, iridium, or the like and having a thickness of, for example, about 0.05 μm are laminated and formed by a process described later, and the piezoelectric element 300 Is configured. 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 electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In this case, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 320. In this embodiment, the lower electrode film 60 is a common electrode of the piezoelectric element 300, and the upper electrode film 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. In any case, the piezoelectric active part 320 is formed for each pressure generating chamber 12. In addition, here, the piezoelectric element 300 and the diaphragm 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.

In addition, as the piezoelectric layer 70 of the present embodiment, a perovskite structure crystal film made of a ferroelectric ceramic material having an electromechanical conversion effect and formed on the lower electrode film 60 can be cited. As a material of the piezoelectric layer 70, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT) or a material obtained by adding a metal oxide such as niobium oxide, nickel oxide or magnesium oxide to the piezoelectric material is suitable. It is. Specifically, lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb (Zr, Ti) O ₃ ), lead zirconate (PbZrO ₃ ), lead lanthanum titanate ((Pb, La), TiO ₃ ) ), Lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ ), lead magnesium titanate zirconate titanate (Pb (Zr, Ti) (Mg, Nb) O ₃ ), etc. Can do. In the present embodiment, lead zirconate titanate (PZT) is used as the piezoelectric layer 70.

  Further, each upper electrode film 80 that is an individual electrode of the piezoelectric element 300 is drawn from the vicinity of the end on the ink supply path 14 side and extended to the insulator film 55, for example, from gold (Au) or the like. Lead electrode 90 is connected.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, a protective substrate 30 having a reservoir portion 31 constituting at least a part of the reservoir 100 is bonded via an adhesive 35. In this embodiment, the reservoir portion 31 is formed across the protective substrate 30 in the thickness direction and across the width direction of the pressure generating chamber 12, and as described above, the reservoir portion 31 is connected to the communication portion 13 of the flow path forming substrate 10. A reservoir 100 is formed which communicates with each other and serves as a common liquid chamber for the pressure generating chambers 12.

  A piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region of the protective substrate 30 that faces the piezoelectric element 300. The protective substrate 30 only needs to have a space that does not hinder the movement of the piezoelectric element 300, and the space may be sealed or unsealed.

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

  The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is provided so as to be exposed in the through hole 33.

  Further, a drive circuit 120 for driving the piezoelectric elements 300 arranged in parallel is fixed on the protective substrate 30. For example, a circuit board or a semiconductor integrated circuit (IC) can be used as the drive circuit 120. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire.

  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), and the sealing film 41 seals one surface of the reservoir portion 31. It has been stopped. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  In such an ink jet recording head of this embodiment, ink is taken in from an external ink supply means (not shown), filled with ink from the reservoir 100 to the nozzle opening 21, and then in accordance with a recording signal from the drive circuit 120. Applying a voltage between each of the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generation chamber 12 to bend and deform the elastic film 50, the insulator film 55, the lower electrode film 60, and the piezoelectric layer 70. As a result, the pressure in each pressure generating chamber 12 increases and 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. 3 to 8 are cross-sectional views showing a method for manufacturing the ink jet recording head.

  First, as shown in FIG. 3A, the flow path forming substrate wafer 110 is thermally oxidized in a diffusion furnace at about 1100 ° C. to form a silicon dioxide film 51 that becomes the elastic film 50 on the surface thereof. In the present embodiment, a silicon wafer having a relatively thick and high rigidity of about 625 μm is used as the flow path forming substrate wafer 110.

Next, as shown in FIG. 3B, a zirconium (Zr) layer is formed on the elastic film 50 (silicon dioxide film 51), and then thermally oxidized in, for example, a diffusion furnace at 500 to 1200 ° C. to form zirconium oxide ( An insulator film 55 made of ZrO ₂ ) is formed.

  Next, as shown in FIG. 3C, a lower electrode film 60 made of, for example, platinum or iridium is formed over the entire surface of the insulator film 55. The lower electrode film 60 can be formed by, for example, a sputtering method.

  Next, a piezoelectric layer 70 made of lead zirconate titanate (PZT) is formed. Here, in this embodiment, a so-called sol-gel in which a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied, dried, gelled, and further fired at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. The piezoelectric layer 70 is formed using this method. The material of the piezoelectric layer 70 is not limited to lead zirconate titanate, and other piezoelectric materials such as relaxor ferroelectrics (for example, PMN-PT, PZN-PT, PNN-PT, etc.) are used. May be. The method for manufacturing the piezoelectric layer 70 is not limited to the sol-gel method, and for example, a MOD (Metal-Organic Decomposition) method or the like may be used.

  As a specific forming procedure of the piezoelectric layer 70, first, as shown in FIG. 4A, a dielectric precursor film 71 which is a PZT precursor film is formed on the lower electrode film 60. 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 dielectric precursor film 71 is heated to a predetermined temperature and dried for a predetermined time (drying step). For example, in the present embodiment, the dielectric precursor film 71 can be dried by holding at 150 to 200 ° C. for 5 to 15 minutes.

Next, the dried dielectric precursor film 71 is degreased by heating it to a predetermined temperature and holding it for a certain time (degreasing step). For example, in this embodiment, the dielectric precursor film 71 is degreased by heating to a temperature of about 300 to 400 ° C. and holding it for about 5 to 10 minutes. Here, degreasing refers, the organic components contained in the dielectric precursor film 71, for _example, is to be detached as _{NO 2, CO 2, H 2} O or the like.

  Next, as shown in FIG. 4B, the dielectric precursor film 71 is crystallized by being heated to a predetermined temperature by the infrared heating device 200 and held for a predetermined time to form a dielectric film 72 (baking). Process).

  Here, as the infrared heating apparatus 200 for heating and baking the dielectric precursor film 71, as shown in FIG. 4B, the dielectric precursor film 71 provided on one surface side of the flow path forming substrate wafer 110. A first heating unit 201 that irradiates the dielectric precursor film 71 with infrared rays in a wavelength region excluding a wavelength region having a high absorption rate of the dielectric precursor film 71, Second heating means 202 is provided in a region opposite to the other surface side (back surface side) of the path forming substrate wafer 110 and irradiates the other surface side of the channel forming substrate wafer 110 with infrared rays. .

  The first heating unit 201 includes a heat source 203 that is irradiated with infrared rays, and a filter 204 provided between the heat source 203 and the flow path forming substrate wafer 110.

  The second heating means 202 is composed only of the heat source 205 that is irradiated with infrared rays. The heat sources 203 and 205 of the first heating unit 201 and the second heating unit 202 irradiate infrared rays including far infrared rays.

  The filter 204 excludes a wavelength region where the absorption rate of the dielectric precursor film 71 is large from infrared rays irradiated by the heat source 203. For example, a reflective film that reflects electromagnetic waves in a predetermined wavelength region, a predetermined wavelength, Examples thereof include a glass substrate provided with an absorption film that absorbs the region.

  Here, the wavelength region having a large infrared absorption rate of the dielectric precursor film 71 to be excluded by the filter 204 means that the dielectric precursor film 71 itself is heated and starts in the film of the dielectric precursor film 71. It is the range where crystals grow. The dielectric precursor film 71 has a different wavelength region with a large infrared absorption rate depending on the film thickness, material, composition ratio, and the like. Therefore, the wavelength region excluded by the filter 204 is the film thickness of the dielectric precursor film 71. It is preferable to select appropriately depending on the material and composition ratio.

  Further, in the wavelength region where the infrared absorption rate of the dielectric precursor film 71 is large, for example, the dielectric precursor film 71 is formed on one surface of a substrate that transmits infrared rays, and the dielectric precursor film 71 is irradiated with infrared rays. And it can acquire by measuring the wavelength range of the infrared rays which permeate | transmitted the dielectric precursor film | membrane 71 by the other surface side of the board | substrate.

  When the dielectric precursor film 71 is heated by such first heating means 201, the dielectric precursor film 71 is directly heated by infrared rays in a wavelength region other than the wavelength region where the dielectric precursor film 71 has a high absorption rate. Without heating, the base of the dielectric precursor film 71, that is, the lower electrode film 60, the insulator film 55, the elastic film 50, and the flow path forming substrate wafer 110 can be heated. The dielectric precursor film 71 can be crystal-grown starting from the base side without crystal growth starting from the film. As a result, the dielectric film 72 can be formed with good crystallinity by taking over crystallinity such as orientation and crystal grain size from the base side. That is, the dielectric film 72 having a desired film thickness can be formed with a relatively small grain size and a uniform crystal without prescribing the film thickness of the dielectric film 72, thereby substantially forming a large crystal. Can be prevented. Thereby, the piezoelectric element 300 having the dielectric film 72 having excellent crystallinity can be formed, and the displacement characteristics of the piezoelectric element 300 can be improved.

  In addition, as the infrared heating device 200, a first heating unit 201 for heating from the dielectric precursor film 71 side on one side of the flow path forming substrate wafer 110, and the other surface side of the flow path forming substrate wafer 110 ( By using the second heating means 202 that heats from the back surface side, the dielectric precursor film 71 is heated and crystallized at a high temperature rise rate to form a dielectric film 72 having good crystallinity. be able to.

  In the firing step of heating using such an infrared heating device 200, it is preferable to heat the dielectric precursor film 71 to 600 to 750 ° C. In this embodiment, the dielectric heating film 200 is set to 700 by the infrared heating device 200 described above. The dielectric precursor film 71 was baked by heating at 5 ° C. for 5 minutes to form the dielectric film 72. In the firing step, the rate of temperature rise is preferably 50 ° C./sec or more, and preferably 100 ° C./sec or more. In this way, by setting the temperature rising rate during firing of the dielectric film 72 to 50 ° C./sec or more, the dielectric film 72 can be performed in a shorter time as compared with the case where the temperature rising rate is low for a long time, and the dielectric film. 72 can be formed of uniform crystals having a relatively small grain size, and the formation of large crystals can be substantially prevented.

  In addition, also in the drying process and the degreasing process described above, by using the infrared heating device 200 used in the firing process, the type of apparatus to be used can be reduced and the manufacturing cost can be reduced. However, in the drying process and the degreasing process, A device other than the infrared heating device 200, such as a hot plate, may be used.

  Then, as shown in FIG. 5A, when the first layer of the dielectric film 72 is formed on the lower electrode film 60, the lower electrode film 60 and the first dielectric film 72 are simultaneously patterned. The patterning of the lower electrode film 60 and the dielectric film 72 can be performed by dry etching such as ion milling, for example.

  Then, after patterning, the dielectric 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, thereby forming a plurality of dielectric films 72 as shown in FIG. A piezoelectric layer 70 having a predetermined thickness is formed. For example, when the film thickness per sol is about 0.1 μm, for example, the entire film thickness of the piezoelectric layer 70 composed of ten dielectric films 72 is about 1.1 μm.

  Then, after the piezoelectric layer 70 is formed, as shown in FIG. 6A, for example, an upper electrode film 80 made of iridium is formed on the entire surface of the flow path forming substrate 10, and then, as shown in FIG. As shown, the piezoelectric element 300 is formed by patterning the piezoelectric 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. 6C, after forming the lead electrode 90 made of, for example, gold (Au) or the like over the entire surface of the flow path forming substrate 10, for example, a mask pattern made of a resist or the like. It is formed by patterning each piezoelectric element 300 via (not shown).

  Next, as illustrated in FIG. 7A, a protective substrate wafer 130 that holds a plurality of patterned piezoelectric elements 300 is bonded onto the flow path forming substrate 10 with, for example, an adhesive 35. The protective substrate wafer 130 is preliminarily formed with a reservoir portion 31, a piezoelectric element holding portion 32, and the like. Further, the protective substrate wafer 130 is made of, for example, a silicon single crystal substrate having a thickness of about 400 μm, and the rigidity of the flow path forming substrate wafer 110 is remarkably improved by bonding the protective substrate wafer 130. Become.

  Next, as shown in FIG. 7B, after the flow path forming substrate wafer 110 is polished to a certain thickness, the flow path forming substrate wafer 110 is further wet-etched with hydrofluoric acid to obtain a predetermined thickness. To. For example, in this embodiment, the flow path forming substrate wafer 110 is processed to have a thickness of about 70 μm by polishing and wet etching.

  Next, as shown in FIG. 7C, a mask film 52 made of, for example, silicon nitride (SiN) is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, as shown in FIG. 8, by performing anisotropic etching (wet etching) using an alkaline solution such as KOH on the flow path forming substrate wafer 110 through the mask film 52, the pressure generating chamber 12, the communication portion 13, an ink supply path 14 and a communication path 15 are formed.

  Thereafter, the mask film 52 on the surface side where the pressure generating chamber 12 of the flow path forming substrate wafer 110 is opened is removed, and unnecessary portions of the peripheral portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are, for example, It is removed by cutting by dicing or the like. 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. The ink jet type recording head having the above-described structure is manufactured by dividing the flow path forming substrate wafer 110 and the like into a single chip size flow path forming substrate 10 as shown in FIG.

(Embodiment 2)
FIG. 9 is a cross-sectional view of a main part of an ink jet recording head which is an example of a liquid jet head according to Embodiment 2 of the present invention. In addition, the same code | symbol is attached | subjected to the member similar to Embodiment 1 mentioned above, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 9, the lower electrode film 60 </ b> A of the piezoelectric element 300 of the present embodiment has an adhesion layer 61 on the substrate (flow path forming substrate 10) side.

  Further, the lower electrode film 60A includes an adhesion layer 61, a platinum layer made of platinum (Pt) on the adhesion layer 61, and a diffusion prevention layer sequentially laminated on the adhesion layer 61 before the piezoelectric layer 70 is formed. When the piezoelectric layer 70 is formed by firing and crystallizing by the manufacturing method described in detail later, the lower electrode film 60A is also heat-treated and alloyed. In this way, when the lower electrode film 60A is heated and alloyed, the amount of diffusion of the adhesion layer 61 into other layers (particularly, the platinum layer) is reduced, and the lower electrode film 60A and the substrate (this embodiment) are reduced. Then, it is made to remain between the insulator films 55). For this reason, the adhesion layer 61 is diffused into the lower electrode film 60A, thereby preventing the adhesion between the substrate (in this embodiment, the insulator film 55) and the lower electrode film 60A from being reduced.

  The adhesion layer 61 is not particularly limited as long as it improves the adhesion between the lower electrode film 60A and the substrate. For example, titanium (Ti), chromium (Cr), tantalum (Ta), zirconium ( Zr) and tungsten (W).

  Here, a method for manufacturing the ink jet recording head of this embodiment will be described. FIG. 10 is a cross-sectional view illustrating a method for manufacturing an ink jet recording head according to Embodiment 2 of the present invention. In addition, about the process similar to Embodiment 1 mentioned above, the overlapping description is abbreviate | omitted.

  Similar to the first embodiment, after the elastic film 50 and the insulator film 55 are formed on the flow path forming substrate wafer 110, as shown in FIG. 10A, the adhesion layer 61, the platinum layer 62, and the diffusion layer are formed. A lower electrode film 60A made of the prevention layer 63 is formed. Specifically, first, the adhesion layer 61 is formed on the insulator film 55. As the adhesion layer 61, for example, at least one element selected from the group consisting of titanium (Ti), chromium (Cr), tantalum (Ta), zirconium (Zr), and tungsten (W) having a thickness of 10 to 50 nm. Is the main component. In this embodiment, 20 nm-thick titanium (Ti) is provided as the adhesion layer 61. Thus, by providing the adhesion layer 61 in the lowermost layer of the lower electrode film 60A, the adhesion between the insulator film 55 and the lower electrode film 60A can be enhanced. Next, a platinum layer 62 made of platinum (Pt) and having a thickness of 50 to 500 nm is formed on the adhesion layer 61. In the present embodiment, the platinum layer 62 is formed with a thickness of 130 nm. Then, a diffusion preventing layer 63 is formed on the platinum layer 62. Thereby, the lower electrode film 60 </ b> A composed of the adhesion layer 61, the platinum layer 62, and the diffusion preventing layer 63 is formed. The diffusion preventing layer 63 prevents the components of the adhesion layer 61 from diffusing into the piezoelectric layer 70 when the piezoelectric layer 70 is formed by firing and crystallizing in a later step. This is to prevent the component 70 from diffusing into the lower electrode film 60A. Such a diffusion preventing layer 63 is at least one selected from the group consisting of iridium (Ir), palladium (Pb), rhodium (Rh), ruthenium (Ru) and osmium (Os) having a thickness of 5 to 20 nm. The main component is one element. In the present embodiment, iridium (Ir) having a thickness of 10 nm is used as the diffusion preventing layer 63.

  Next, a piezoelectric layer 70 made of lead zirconate titanate (PZT) is formed. Specifically, as shown in FIG. 10B, a dielectric precursor film 71 which is a PZT precursor film is formed on the lower electrode film 60A. Next, the dried dielectric precursor film 71 is degreased by heating it to a predetermined temperature and holding it for a certain time (degreasing step).

  Next, as shown in FIG. 10C, the dielectric precursor film 71 is crystallized by being heated to a predetermined temperature by the infrared heating device 200A and held for a certain period of time to form a dielectric film 72 (baking). Process).

  Here, as the infrared heating apparatus 200A for heating and baking the dielectric precursor film 71, as shown in FIG. 10C, the dielectric precursor film 71 provided on one side of the flow path forming substrate wafer 110. A first heating means 201A for irradiating the dielectric precursor film 71 with infrared rays in a wavelength region excluding a wavelength region having a high absorption rate of the dielectric precursor film 71; Provided in a region opposite to the other surface side (back surface side) of the path forming substrate wafer 110, is provided with second heating means 202 </ b> A that irradiates the other surface side of the channel forming substrate wafer 110 with infrared rays. .

  The first heating means 201 </ b> A includes a heat source 203 </ b> A to which infrared rays are irradiated, and a filter 204 provided between the heat source 203 </ b> A and the flow path forming substrate wafer 110.

  Further, the second heating means 202A is composed only of a heat source 205A irradiated with infrared rays. The heat sources 203A and 205A of the first heating unit 201A and the second heating unit 202A irradiate infrared rays including far infrared rays.

  Here, the color temperature of the heat source 205A of the second heating unit 202A is lower than the color temperature of the heat source 203A of the first heating unit 201A. Thereby, the temperature at which the substrate (flow path forming substrate wafer 110) side is heated from the adhesion layer 61 can be made lower than the temperature at which the dielectric film 72 side is heated from the adhesion layer 61. Therefore, a temperature gradient that decreases from the dielectric film 72 side toward the substrate (flow path forming substrate wafer 110) side can be provided with the adhesion layer 61 interposed therebetween.

  Therefore, even when the lower electrode film 60A is heated at the same time when the dielectric film 72 is baked, the amount of the adhesion layer 61 diffused into the lower electrode film 60A is reduced, and the lower electrode film 60A and the substrate ( In this embodiment, the adhesion layer 61 can remain between the insulating film 55). This prevents a decrease in adhesion between the lower electrode film 60A and the substrate (insulator film 55) due to the diffusion of the adhesion layer 61 into the lower electrode film 60A. Damage to the piezoelectric element 300 due to peeling of the film 60A can be prevented, print quality can be maintained, and reliability can be improved.

  The diffusion condition of the adhesion layer 61 is determined by the concentration gradient of the adhesion layer 61 and the temperature gradient to be heated. For this reason, the diffusion of the adhesion layer 61 can be reduced by controlling the temperature gradient as in the present embodiment.

In addition, the flow path forming substrate wafer 110 made of silicon is not heated by passing infrared rays, and the elastic film 50 made of silicon dioxide (SiO ₂ ) absorbs a wavelength of 2 nm, and therefore the heat of absorption is high. When heated without a temperature gradient, heat is generated from the lower side of the lower electrode film 60A (adhesion layer 61 side), and the lower side in the thickness direction of the lower electrode film 60A is heated at a higher temperature than the upper side. The Therefore, the adhesion layer 61 provided on the higher temperature side diffuses into the lower electrode film 60A on the lower temperature side. In the present embodiment, since the lower electrode film 60A is heated with a temperature gradient, it is possible to prevent the adhesion layer 61 from diffusing into the lower electrode film 60A and reducing the adhesion of the lower electrode film 60A. .

Incidentally, the insulator film 55 made of zirconium oxide (ZrO ₂ ) absorbs a wavelength of 20 nm, and the platinum layer 62 and the diffusion prevention layer 63 made of a platinum group metal reflect infrared rays. The dielectric film 72 made of PZT absorbs a wavelength of 20 to 40 nm.

  Further, in the wavelength region where the infrared absorption rate of the dielectric precursor film 71 is large, for example, the dielectric precursor film 71 is formed on one surface of a substrate that transmits infrared rays, and the dielectric precursor film 71 is irradiated with infrared rays. And it can acquire by measuring the wavelength range of the infrared rays which permeate | transmitted the dielectric precursor film | membrane 71 by the other surface side of the board | substrate.

  Furthermore, in this embodiment, since the color temperature of the heat source 203A of the first heating unit 201A is set higher than the color temperature of the heat source 205A of the second heating unit 202A, the dielectric film 72 is directly heated and has a large particle size. In this embodiment, the filter 204 is provided in the first heating means 201A as in the first embodiment, so that the dielectric precursor film 71 has a wavelength region other than the wavelength region where the absorption rate is high. The base of the dielectric precursor film 71 can be heated without directly heating the dielectric precursor film 71 with infrared rays in the wavelength region. Accordingly, the dielectric precursor film 71 can be crystal-grown starting from the base side without crystal growth starting from the film of the dielectric precursor film 71, and the orientation, crystal grain size, etc. The dielectric film 72 can be formed with good crystallinity by taking over the crystallinity.

  Further, as the infrared heating apparatus 200A, first heating means 201A for heating from the dielectric precursor film 71 side on one side of the flow path forming substrate wafer 110, and the other side of the flow path forming substrate wafer 110 ( By using the second heating means 202A that heats from the back surface side, the dielectric precursor film 71 is heated and crystallized at a high temperature rising rate to form the dielectric film 72 having good crystallinity. be able to.

  Since the subsequent steps are the same as those in the first embodiment described above, a duplicate description is omitted.

  In this embodiment, the adhesion layer 61, the platinum layer 62, and the diffusion prevention layer 63 are sequentially laminated to form the lower electrode film 60A. However, the lower electrode film 60A is disposed on the substrate (insulator film 55) side. If it has 61, it will not specifically limit about another material. Further, the material of the adhesion layer 61 is not limited to the above as long as it is diffused into the lower electrode film 60A by heating when the piezoelectric layer 70 is formed.

(Other embodiments)
While the embodiments of the present invention have been described above, the basic configuration of the ink jet recording head is not limited to that described above. For example, in the first and second embodiments described above, the lower electrode film 60 made of platinum or iridium, the lower electrode film 60A made of the adhesion layer 61, the platinum layer 62, and the diffusion prevention layer 63 are exemplified, but the present invention is not particularly limited thereto. For example, before the dielectric precursor film 71 is formed, seed titanium or the like serving as a nucleus for crystal growth of the dielectric film 72 may be provided on the lower electrode films 60 and 60A.

  In the first and second embodiments described above, the flow path forming substrate 10 and the flow path forming substrate wafer 110 are exemplified by the silicon single crystal substrate having the (110) crystal plane orientation, but the present invention is not particularly limited thereto. For example, a silicon single crystal substrate having a (100) crystal plane orientation may be used, or a material such as an SOI substrate or glass may be used.

  In the first and second embodiments described above, the ink jet recording head has been described as an example of the liquid ejecting head. However, the present invention is widely applied to all liquid ejecting heads and ejects liquids other than ink. Of course, the invention can also be applied to a liquid jet head. 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.

  Further, the present invention is not limited to a method for manufacturing a liquid jet head having a piezoelectric element. That is, it goes without saying that the present invention is not limited to a method for manufacturing a piezoelectric layer made of a dielectric film, but can be applied to a method for manufacturing a dielectric film made of any dielectric material.

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 plan view and a cross-sectional view of the recording head according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the recording head manufacturing method according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the recording head manufacturing method according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the recording head manufacturing method according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the recording head manufacturing method according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the recording head manufacturing method according to the first embodiment. FIG. 4 is a cross-sectional view illustrating the recording head manufacturing method according to the first embodiment. FIG. 6 is a cross-sectional view of a main part of a recording head according to a second embodiment. 5 is a cross-sectional view illustrating a method for manufacturing a recording head according to Embodiment 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 13 Communication part, 14 Ink supply path, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Reservoir part, 32 Piezoelectric element holding part, 40 Compliance board, 60, 60A Bottom Electrode film, 61 Adhesion layer, 62 Platinum layer, 63 Diffusion prevention layer, 70 Piezoelectric layer, 71 Dielectric precursor film, 72 Dielectric film, 80 Upper electrode film, 90 Lead electrode, 100 Reservoir, 110 Channel formation substrate Wafer, 120 drive circuit, 121 connection wiring, 130 protective substrate wafer, 200, 200A infrared heating device, 201, 201A first heating means, 202, 202A second heating means, 204 filter, 300 piezoelectric element

Claims (9)

Applying a sol of an organometallic compound to one side of the substrate to form a dielectric precursor film; and an absorptance of the dielectric precursor film from a region of the substrate facing the dielectric precursor film And irradiating infrared rays in a wavelength region excluding a large wavelength region, and irradiating infrared rays from the other surface side of the substrate to heat-fire and crystallize the dielectric precursor film. A method for manufacturing a dielectric film. Irradiation of infrared light in a wavelength region excluding a wavelength region having a high absorption rate of the dielectric precursor film includes a heat source that irradiates infrared light, and a filter that excludes a wavelength region in which the dielectric precursor film has a high absorption rate. The method for producing a dielectric film according to claim 1, wherein the dielectric film is produced by using the dielectric film. The method further comprises a drying step of drying the dielectric precursor film and a degreasing step of degreasing the dried dielectric precursor film before the step of crystallizing the dielectric precursor film. Item 3. The method for producing a dielectric film according to Item 1 or 2. 4. The dielectric film according to claim 1, wherein the step of crystallizing the dielectric precursor film by heating and baking is performed at a temperature rising rate of 100 ° C./sec or more. 5. Production method. Forming a piezoelectric layer, comprising: forming a lower electrode on the substrate; forming a piezoelectric layer on the lower electrode; and forming an upper electrode on the piezoelectric layer. A method of manufacturing a piezoelectric element, wherein the step of performing is a method of manufacturing a dielectric film manufactured by the manufacturing method according to claim 1. The lower electrode has an adhesion layer on the substrate side, and in the step of crystallizing the dielectric precursor film by heating and baking, the color temperature of irradiating infrared rays from the other surface side of the substrate is set to one of the substrates. 6. The method of manufacturing a piezoelectric element according to claim 5, wherein the temperature is lower than a color temperature of a heat source that irradiates infrared rays from the side. The method for manufacturing a piezoelectric element according to claim 6, wherein the adhesion layer is made of a material mainly composed of titanium. Infrared light in a wavelength region that is provided in a region opposite to the dielectric film side of the substrate having a dielectric precursor film provided on one side and excluding a wavelength region in which the dielectric precursor film has a high absorption rate An infrared heating apparatus comprising: a first heating unit that irradiates the substrate; and a second heating unit that is provided on the other surface side of the substrate and irradiates infrared light on the other surface side of the substrate. . The first heating means includes a heat source that emits infrared rays, and a filter that is provided between the heat source and the substrate and excludes a wavelength region having a large absorption rate of the dielectric precursor film. The infrared heating device according to claim 8, wherein

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