JP2014184644A - Liquid jet head manufacturing method and piezoelectric element manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a method for manufacturing a liquid jet head capable of easily etching a piezoelectric layer while suppressing side etching; and a method for manufacturing a piezoelectric element.SOLUTION: A method for manufacturing a liquid jet head is for manufacturing the liquid jet head including: a channel formation substrate provided with a liquid channel that communicates with a nozzle opening for discharging a liquid; and a piezoelectric element that is disposed on the channel formation substrate and applies a pressure to the liquid channel. The method includes: forming a piezoelectric film composed of a piezoelectric material for a piezoelectric element; performing a plasma processing with respect to a predetermined position of the piezoelectric film; and performing a patterning of the piezoelectric film by wet etching.

Description

  The present invention relates to a method for manufacturing a liquid jet head and a method for manufacturing a piezoelectric element.

  2. Description of the Related Art Conventionally, a liquid ejecting head that ejects liquid droplets from a nozzle that communicates with a pressure generating chamber by deforming a piezoelectric element to cause pressure fluctuation in the liquid in the pressure generating chamber is known. A typical example is an ink jet recording head that ejects ink droplets as droplets.

  The ink jet recording head includes, for example, a piezoelectric element on one surface side of a flow path forming substrate provided with a pressure generating chamber communicating with a nozzle opening, and the diaphragm is deformed by driving the piezoelectric element so as to enter the pressure generating chamber. By causing a pressure change, an ink droplet is ejected from the nozzle.

  Such a piezoelectric element is composed of a first electrode, a piezoelectric layer, and a second electrode provided on the diaphragm. In the case of forming a piezoelectric element, it is known that a piezoelectric film is laminated on the second electrode so as to have a predetermined thickness, and this is removed by dry etching so as to have a predetermined shape, thereby forming a piezoelectric layer. (For example, refer to Patent Document 1).

JP 2008-053395 A (FIG. 6, paragraph 0056, etc.)

  When the piezoelectric film is removed by dry etching as described above, there is a problem that it takes time to etch, and it takes time to manufacture the piezoelectric element, and it is difficult to improve the throughput.

  In contrast, wet etching has the advantage that the etching time is short, but if patterning is performed by wet etching, side etching that occurs between the resist and the piezoelectric body is large, and fine processing is performed to form the piezoelectric element. There is a problem that is difficult.

  In this case, it is conceivable to adjust the wet etching solution in order to suppress side etching, but a ferroelectric piezoelectric material such as lead zirconate titanate (PZT) is used for the piezoelectric film. There are a wide variety of materials and deposition methods. It is considered that the optimal wet etchant differs depending on the film formation conditions and composition of the piezoelectric film, so it is difficult to prepare an optimal wet etchant for each film formation condition and composition. If an additive is added to prepare the liquid, there is a problem that the cost increases.

  Such a problem exists not only in an ink jet recording head but also in a liquid ejecting head that ejects liquid other than ink.

  In view of such circumstances, it is an object of the present invention to provide a method for manufacturing a liquid jet head and a method for manufacturing a piezoelectric element that can easily etch a piezoelectric layer while suppressing side etching.

  The method of manufacturing a liquid jet head according to the present invention includes a flow path forming substrate provided with a liquid flow path communicating with a nozzle opening for discharging a liquid, and a pressure applied to the liquid flow path provided on the flow path forming substrate. A method of manufacturing a liquid jet head comprising: a piezoelectric element that includes: a step of forming a piezoelectric film made of a piezoelectric body of the piezoelectric element; and a step of performing a plasma treatment on a predetermined position of the piezoelectric film; And patterning the piezoelectric film by wet etching. By performing the plasma treatment on a predetermined position of the piezoelectric film, side etching in the process of patterning the piezoelectric film by wet etching can be easily suppressed.

  A bias voltage is preferably applied to the piezoelectric film during the plasma treatment. By applying the bias voltage, the plasma processing can be performed more appropriately, and the side etching can be further suppressed.

  The piezoelectric film is preferably made of a metal oxide, and the gas introduced in the plasma treatment is a gas containing oxygen. If the piezoelectric film is made of an oxide, even if oxygen is mixed into the piezoelectric film by plasma treatment, it is easy to suppress deterioration of the film quality.

  It is preferable to have a step of heating the piezoelectric film after the wet etching. By heating, the deterioration of the film quality of the piezoelectric film due to the plasma treatment can be suppressed.

  As a preferred embodiment of the present invention, the piezoelectric film is made of any one of lead zirconate titanate, barium titanate, and iron titanate.

  As preferable embodiment of this invention, it is mentioned that the wet etching liquid used for the said wet etching contains at least 1 or more among hydrochloric acid, nitric acid, and hydrofluoric acid.

  The predetermined position is preferably in the vicinity of a region where a mask is provided when the wet etching of the piezoelectric film is performed. By performing plasma treatment at least in this region, appropriate wet etching can be performed while further suppressing deterioration in film quality.

  As a preferred embodiment of the present invention, it is mentioned that a mask provided when performing the wet etching is made of an organic material.

  A method for manufacturing a piezoelectric element according to the present invention is a method for manufacturing a piezoelectric element including a piezoelectric film made of a piezoelectric body, and a first electrode and a second electrode provided on both surfaces of the piezoelectric film, respectively. The method includes a step of forming the piezoelectric film, a step of performing plasma treatment on a predetermined position of the piezoelectric film, and a step of patterning the piezoelectric film by wet etching. In the method for manufacturing a piezoelectric element of the present invention, side etching in the step of patterning the piezoelectric film by wet etching can be easily suppressed by the step of performing plasma processing on a predetermined position of the piezoelectric film.

FIG. 2 is an exploded perspective view of the ink jet recording head according to the first embodiment. 2A and 2B are a plan view and a cross-sectional view of the ink jet recording head according to Embodiment 1. 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 partially enlarged cross-sectional view in the manufacturing process 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. 5 is a cross-sectional view illustrating a method for manufacturing a recording head according to Embodiment 2. FIG. 5 is a cross-sectional view illustrating a method for manufacturing a recording head according to Embodiment 2. FIG. 3 is a cross-sectional SEM photograph showing the results of Experimental Example 1. 6 is a cross-sectional SEM photograph showing the results of Experimental Example 2. 1 is a schematic view of an ink jet recording apparatus according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment 1)
FIG. 1 is an exploded perspective view of an ink jet recording head that is an example of a liquid jet head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a cross-sectional view of the ink jet recording head.

  As shown in the drawing, a pressure generating chamber 12 is formed in a flow path forming substrate 10 provided in an ink jet recording head I which is an example of a liquid ejecting head of the present embodiment. The pressure generating chambers 12 partitioned by the plurality of partition walls 11 are arranged in parallel along the direction in which the plurality of nozzle openings 21 for discharging the same color ink are arranged in parallel. Hereinafter, this direction is referred to as a direction in which the pressure generating chambers 12 are arranged side by side or a first direction X. Further, a direction orthogonal to the first direction X is defined as a second direction Y in the plane of the flow path forming substrate 10. Furthermore, a direction orthogonal to the first direction X and the second direction Y is defined as a third direction Z. Although one row of the pressure generation chambers 12 arranged in parallel in the first direction X is shown in the drawing, a plurality of rows of the pressure generation chambers 12 may be arranged in the second direction Y. .

  An ink supply path 13 and a communication path 14 are partitioned by a plurality of partition walls 11 at one end side in the longitudinal direction of the pressure generating chamber 12 of the flow path forming substrate 10, that is, one end side in the second direction Y. . On the outside of the communication passage 14 (on the side opposite to the pressure generation chamber 12 in the second direction Y), a communication portion that constitutes a part of the manifold 100 serving as a common ink chamber (liquid chamber) of each pressure generation chamber 12. 15 is formed. That is, the flow path forming substrate 10 is provided with a liquid flow path including a pressure generation chamber 12, an ink supply path 13, a communication path 14, and a communication portion 15.

  On one side of the flow path forming substrate 10, that is, the surface where the liquid flow path such as the pressure generation chamber 12 opens, a nozzle plate 20 having a nozzle opening 21 communicating with each pressure generation chamber 12 is provided with an adhesive. Or a heat-welded film or the like. In other words, the nozzle openings 21 are arranged in the nozzle plate 20 in the first direction X.

  A diaphragm 50 is formed on the other surface side of the flow path forming substrate 10. The diaphragm 50 according to the present embodiment includes an elastic film 51 formed on the flow path forming substrate 10 and an insulator film 52 formed on the elastic film 51. The liquid flow path such as the pressure generation chamber 12 is formed by anisotropically etching the flow path forming substrate 10 from one surface, and the other surface of the liquid flow path such as the pressure generation chamber 12 is a diaphragm. 50 (elastic film 51).

  On the insulator film 52, a first electrode 60 having a thickness of, for example, about 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1.0 μm, and a thickness of, for example, about 0.05 μm. A piezoelectric element 300 composed of the second electrode 80 is formed. In this embodiment, the piezoelectric element 300 provided on the substrate (the flow path forming substrate 10) functions as an actuator device.

  Hereinafter, the piezoelectric element 300 constituting the actuator device will be described in detail.

  As shown in FIG. 2, the first electrode 60 constituting the piezoelectric element 300 is separated for each pressure generation chamber 12 and constitutes an individual electrode independent for each piezoelectric element 300. The first electrode 60 is formed with a width narrower than the width of the pressure generation chamber 12 in the first direction X of the pressure generation chamber 12. That is, in the first direction X of the pressure generation chamber 12, the end portion of the first electrode 60 is located inside the region facing the pressure generation chamber 12. In the second direction Y of the pressure generation chamber 12, both end portions of the first electrode 60 are extended to the outside of the pressure generation chamber 12. The material of the first electrode 60 is not particularly limited as long as it is a metal material. For example, metals such as Ti, Pt, Ta, Ir, Sr, In, Sn, Au, Al, Fe, Cr, Ni, and Cu are used. Alternatively, only one of these materials, or a mixture or stack of two or more of these materials may be used as the first electrode 60.

  The piezoelectric layer 70 is continuously provided over the first direction X so that the second direction Y has a predetermined width. The width of the piezoelectric layer 70 in the second direction Y is wider than the length of the pressure generation chamber 12 in the second direction Y. Therefore, in the second direction Y of the pressure generation chamber 12, the piezoelectric layer 70 is provided to the outside of the pressure generation chamber 12.

  The end portion of the piezoelectric layer 70 on the one end side in the second direction Y of the pressure generation chamber 12 (in the present embodiment, on the ink supply path side) is located outside the end portion of the first electrode 60. That is, the end portion of the first electrode 60 is covered with the piezoelectric layer 70. The end portion of the piezoelectric layer 70 on the other end side in the second direction Y of the pressure generation chamber 12 is located on the inner side (the pressure generation chamber 12 side) than the end portion of the first electrode 60.

  Note that a lead electrode 90 made of, for example, gold (Au) or the like is connected to the first electrode 60 extended to the outside of the piezoelectric layer 70. Although not shown, the lead electrode 90 constitutes a terminal portion to which connection wiring connected to a drive circuit or the like is connected.

  In addition, the piezoelectric layer 70 is formed with a recess 71 that faces each partition wall 11. The width of the recess 71 in the first direction X is substantially the same as or wider than the width of each partition 11 in the first direction X. In other words, the piezoelectric layer 70 is continuously formed along the first direction X across the pressure generation chambers 12, and a portion facing each partition wall 11 is removed to form a recess 71. The recess 71 can suppress the rigidity of the portion of the vibration plate 50 that faces the end portion in the width direction of the pressure generating chamber 12 (so-called arm portion of the vibration plate 50), and thus the piezoelectric element 300 can be displaced favorably.

Examples of the piezoelectric layer 70 include a perovskite structure crystal film (perovskite crystal) made of a ferroelectric ceramic material having an electromechanical conversion effect and formed on the first electrode 60. 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 used. be able to. 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.

The material of the piezoelectric layer 70 is not limited to a lead-based piezoelectric material including lead, and a lead-free piezoelectric material not including lead can also be used. Examples of lead-free piezoelectric materials include bismuth ferrate ((BiFeO ₃ ), approximately “BFO”), barium titanate ((BaTiO ₃ ), approximately “BT”), and sodium potassium niobate ((K, Na). ) (NbO ₃ ), approximately “KNN”), potassium sodium niobate lithium ((K, Na, Li) (NbO ₃ )), potassium sodium tantalate niobate ((K, Na, Li) (Nb, Ta) ) O ₃ ), potassium bismuth titanate ((Bi _1/2 K _1/2 ) TiO ₃ , approximately “BKT”), sodium bismuth titanate ((Bi _1/2 Na _1/2 ) TiO ₃ , approximately “BNT” "), bismuth manganate (BiMnO _3, substantially" BM "), bismuth, potassium, composite oxides having a perovskite structure that contains titanium and iron _{(x [(Bi x K 1} -x) TiO 3] - (1 x) [BiFeO _3], approximately "BKT-BF"), bismuth, iron, composite oxide having a perovskite structure containing barium and titanium ((1-x) [BiFeO 3] -x [BaTiO 3], approximately " BFO-BT ”) or a metal added with manganese, cobalt, chromium or the like ((1-x) [Bi (Fe _1-y M _y ) O ₃ ] -x [BaTiO ₃ ] (M is Mn, Co or Cr)).

  In the present embodiment, the piezoelectric layer 70 is patterned by wet etching while suppressing side etching as will be described in detail later. Therefore, the piezoelectric layer 70 of the present embodiment is simply formed in a desired fine shape.

  The second electrode 80 is continuously provided on the piezoelectric layer 70 in the first direction X of the pressure generating chamber 12 and constitutes a common electrode common to the plurality of piezoelectric elements 300. The end portion of the second electrode 80 on one end side in the second direction Y of the pressure generating chamber 12 is located outside the end portion of the piezoelectric layer 70.

  The material of the second electrode 80 is not particularly limited as long as it is a metal material. For example, the same material as that of the first electrode 60 can be used. In the present embodiment, the second electrode 80 is made of nickel (Ni).

  The piezoelectric element 300 having such a configuration is displaced by applying a voltage between the first electrode 60 and the second electrode 80. That is, by applying a voltage between both electrodes, a piezoelectric strain is generated in the piezoelectric layer 70 sandwiched between the first electrode 60 and the second electrode 80. A portion where piezoelectric distortion occurs in the piezoelectric layer 70 when a voltage is applied to both electrodes is referred to as an active portion 320. On the other hand, a portion where no piezoelectric distortion occurs in the piezoelectric layer 70 is referred to as an inactive portion. In the active part 320 in which piezoelectric distortion occurs in the piezoelectric layer 70, a part facing the pressure generation chamber 12 is referred to as a flexible part, and a part outside the pressure generation chamber 12 is referred to as a non-flexible part.

  In the present embodiment, all of the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are continuously provided to the outside of the pressure generation chamber 12 in the second direction Y of the pressure generation chamber 12. That is, the active part 320 is continuously provided to the outside of the pressure generating chamber 12. For this reason, a portion of the active portion 320 facing the pressure generation chamber 12 of the piezoelectric element 300 is a flexible portion, and a portion outside the pressure generation chamber 12 is a non-flexible portion.

  Since the first electrode 60 is separated for each pressure generation chamber 12 as described above, the piezoelectric element 300 has the second direction Y, that is, the longitudinal direction of the active portion 320 (second direction). A step of the first electrode 60 is formed along the direction Y).

  As shown in FIGS. 1 and 2, a protective substrate 30 that protects the piezoelectric element 300 is bonded to the flow path forming substrate 10 on which the piezoelectric element 300 is formed by an adhesive 35. The protective substrate 30 is provided with a piezoelectric element holding portion 31 that is a recess that defines a space for accommodating the piezoelectric element 300. The protective substrate 30 is provided with a manifold portion 32 that constitutes a part of the manifold 100. The manifold portion 32 penetrates the protective substrate 30 in the thickness direction and is formed across the width direction of the pressure generating chamber 12 and communicates with the communication portion 15 of the flow path forming substrate 10 as described above. The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The lead electrode 90 connected to the first electrode 60 of each piezoelectric element 300 is exposed in the through hole 33. One end of a connection wiring connected to a drive circuit (not shown) is connected to the lead electrode 90 connected to the first electrode 60 of each piezoelectric element 300 in the through hole 33.

  On the protective substrate 30, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded. The sealing film 41 is made of a material having low rigidity and flexibility, and one surface of the manifold portion 32 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal. Since the area of the fixing plate 42 facing the manifold 100 is an opening 43 that is completely removed in the thickness direction, one surface of the manifold 100 is sealed only with a flexible sealing film 41. Has been.

  In such an ink jet recording head I of this embodiment, ink is taken in from an ink inlet connected to an external ink supply means (not shown), and the interior of the liquid flow path is filled with ink from the manifold 100 to the nozzle opening 21. Thereafter, a voltage is applied between each of the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12 in accordance with a recording signal from the drive circuit. As a result, the diaphragm 50 is bent and deformed together with the piezoelectric element 300 to increase the pressure in each pressure generating chamber 12, and an ink droplet is ejected from each nozzle opening 21.

  Here, a method for manufacturing the ink jet recording head of the present embodiment will be described. 3 to 8 are cross-sectional views in the first direction X showing the method of manufacturing the ink jet recording head.

  First, as shown in FIG. 3A, an elastic film 51 is formed on the surface of a flow path forming substrate wafer 110 that is a silicon wafer. In the present embodiment, the elastic film 51 made of silicon dioxide is formed by thermally oxidizing the flow path forming substrate wafer 110. Of course, the method of forming the elastic film 51 is not limited to thermal oxidation, and may be formed by sputtering, CVD, or the like.

  Next, as shown in FIG. 3B, an insulator film 52 made of zirconium oxide is formed on the elastic film 51. The insulator film 52 may be formed by thermally oxidizing zirconium after being formed by sputtering or the like, or zirconium oxide may be formed by reactive sputtering. A diaphragm 50 is formed by the elastic film 51 and the insulator film 52.

  Next, as shown in FIG. 3C, the first electrode 60 is formed on the entire surface of the insulator film 52. The material of the first electrode 60 is not particularly limited, but when lead zirconate titanate (PZT) is used as the piezoelectric layer 70, it is desirable that the material has little change in conductivity due to diffusion of lead oxide. For this reason, platinum, iridium, etc. are used suitably as a material of the 1st electrode 60. FIG. Moreover, the 1st electrode 60 can be formed by sputtering method, PVD method (physical vapor deposition method), etc., for example.

  Next, as shown in FIG. 4A, the first electrode 60 is patterned. The patterning can be performed by dry etching such as ion milling, for example.

Although not particularly shown, a crystal seed layer made of titanium (Ti) may be formed on the first electrode 60. By providing the crystal seed layer on the first electrode 60, when the piezoelectric layer 70 is formed on the first electrode 60 via the crystal seed layer, the preferred orientation direction of the piezoelectric layer 70 is set to (100). The piezoelectric layer 70 that can be controlled and is suitable as an electromechanical conversion element can be obtained. As the crystal seed layer, titanium (Ti) or titanium oxide (TiO ₂ ) may be used, and materials other than titanium and titanium oxide, such as lanthanum nickel oxide, may be used.

  Next, in this embodiment, the 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 complex is dissolved / dispersed in a solvent 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 the method. The method for manufacturing the piezoelectric layer 70 is not limited to the sol-gel method, and for example, using a MOD (Metal-Organic Decomposition) method, a PVD (Physical Vapor Deposition) method such as a sputtering method or a laser ablation method. Also good. That is, the piezoelectric layer 70 may be formed by either a liquid phase method or a gas phase method.

  As a specific procedure for forming the piezoelectric layer 70, first, as shown in FIG. 4B, a piezoelectric precursor film 73, which is a PZT precursor film, is formed on the first electrode 60 and the insulator film 52. Film. That is, a sol (solution) containing a metal complex is applied onto the flow path forming substrate wafer 110 on which the first electrode 60 is formed (application step). The method for applying the sol is not particularly limited, and examples thereof include a spin coat method using a spin coater and a slit coat method using a slit coater. Next, the piezoelectric precursor film 73 is heated to a predetermined temperature and dried for a predetermined time (drying step). For example, in the present embodiment, the piezoelectric precursor film 73 can be dried by holding at 170 to 180 ° C. for 8 to 30 minutes.

Next, the dried piezoelectric precursor film 73 is degreased by heating to a predetermined temperature and holding for a certain time (degreasing step). For example, in this embodiment, the piezoelectric precursor film 73 is degreased by heating to a temperature of about 300 to 400 ° C. and holding for about 10 to 30 minutes. Note that the degreasing here, the organic components contained in the piezoelectric precursor film 73, for _example, is to be detached as _{NO 2, CO 2, H 2} O or the like.

  Next, the piezoelectric precursor film 73 is crystallized by being heated to a predetermined temperature and held for a predetermined time, thereby forming the piezoelectric film 74 (firing process). In this firing step, the piezoelectric precursor film 73 is preferably heated to 700 ° C. or higher. In the firing step, it is preferable that the temperature rising rate is 50 ° C./sec or more. Thereby, the piezoelectric film 74 having excellent characteristics can be obtained.

  As shown in FIG. 4B, the piezoelectric layer 70 composed of a plurality of piezoelectric films 74 is formed by repeating the piezoelectric film forming process including the coating process, the drying process, the degreasing process, and the baking process described above a plurality of times. Form. The piezoelectric film 74 may be formed one layer at a time, or a plurality of layers may be formed by repeating a coating process, a drying process, and a degreasing process to form a plurality of piezoelectric precursor films 73 and performing a baking process on them. Alternatively, the piezoelectric film 74 may be formed.

  In addition, as a heating apparatus used in such a drying process, a degreasing process, and a baking process, for example, a hot plate, an RTP (Rapid Thermal Processing) apparatus that heats by irradiation with an infrared lamp, or the like can be used.

  Next, as shown in FIG. 4C, plasma processing is performed on the piezoelectric layer 70. The plasma processing is to expose the surface of the piezoelectric layer 70 to plasma, and the plasma processing layer 75 is formed on the surface of the piezoelectric layer 70 by such plasma processing. Such plasma treatment is performed by generating plasma by discharging while introducing a plasma generating gas into the chamber.

  The plasma generating gas may be any gas that is normally used for generating plasma. For example, a fluorine-based gas such as chlorine gas, oxygen gas, or fluorine carbide, or a rare gas such as helium, neon, or argon may be used. These mixed gases may be used, and another rare gas may be mixed as a carrier gas.

Of these, the plasma generating gas is preferably chlorine gas (Cl ₂ ), oxygen gas (O ₂ ), carbon tetrafluoride (CF ₄ ), or argon (Ar). This is because side etching described later can be well suppressed. In particular, it is preferable to use oxygen gas. Oxygen gas can suppress side etching well, and even if it enters the surface of the piezoelectric layer by plasma treatment, the piezoelectric layer itself is an oxide and therefore does not greatly affect the displacement characteristics of the piezoelectric layer 70. It is.

  The plasma generation gas is introduced into the processing chamber at, for example, 10 to 200 sccm. In this embodiment, it is introduced at 100 sccm.

  A discharge voltage is 800-2000W, for example, and is 1000W in this embodiment.

  Further, during the discharge, a plasma treatment is performed while maintaining the plasma by applying a bias voltage to the substrate side, ie, the piezoelectric layer 70. The bias voltage is 100 to 500 W, for example, and is 100 W in this embodiment.

  The time for performing the plasma treatment is about 1 to 30 seconds.

  Next, as shown in FIG. 5A, a resist film 78 is formed on the piezoelectric layer 70. Here, the resist film 78 functions as a mask and is made of an organic material. As the organic material, for example, a novolak resin obtained by a condensation reaction of phenol or o-, m- or p-cresol, xylenol or a mixture of these phenol compounds with formaldehyde is preferably used. A novolac resin is suitable as a resist material because it can be patterned with high accuracy.

  In this embodiment, a novolac resin is used as the resist film 78. Note that when the resist film 78 is made of an organic material, the amount of side etching can be more effectively suppressed, but a so-called hard mask may be used.

  Next, as shown in FIG. 5B, patterning is performed by a photolithography method so that a resist film 78 is formed in each region where each piezoelectric element 300 of the piezoelectric layer 70 is formed.

  Next, as shown in FIG. 5C, the piezoelectric layer 70 is patterned into regions facing the pressure generation chambers 12 by wet etching. In this case, in this embodiment, side etching can be suppressed by forming the plasma processing layer 75 on the surface of the piezoelectric layer 70.

  That is, as shown in FIG. 6A, which is a partially enlarged view of FIG. 5C, in this embodiment, the wet etching liquid is placed inside the resist film 78 because the plasma treatment layer 75 is formed. The side etching amount between the piezoelectric layer 70 and the resist film 78 is small. On the other hand, in the case of FIG. 6B showing the case where the plasma treatment layer 75 is not formed, the wet etching solution wraps around the inside of the resist film 78, and the side between the piezoelectric layer 70 and the resist film 78. The etching amount is large.

  As described above, in this embodiment, the side etching is well suppressed by performing the plasma treatment. Thus, in the present embodiment, the piezoelectric layer 70 is formed easily and with high throughput by wet etching.

  A known method can be used for wet etching. As the wet etching solution, one containing at least one selected from hydrofluoric acid, nitric acid and hydrochloric acid is used. For example, a two-step process in which wet etching is performed only with a BHF (buffered hydrofluoric acid) 20 wt% solution, a mixed solution of nitric acid and hydrochloric acid, or a BHF 20% wt solution and the residue is removed with nitric acid may be used.

  Next, as shown in FIG. 7A, the resist film 78 is removed, and the second electrode 80 is formed over the piezoelectric layer 70 and the insulator film 52. The second electrode 80 can also be formed by a sputtering method, a PVD method (physical vapor deposition method), an electroless plating method, or the like.

  Next, as shown in FIG. 7B, the plasma treatment layer 75 formed on the piezoelectric layer 70 is removed by performing a heat treatment. That is, the characteristics of the plasma treatment layer are recovered by heat treatment. The heating in this case is performed at 400 to 900 ° C, and in this embodiment, 700 ° C.

  Next, as shown in FIG. 8A, a protective substrate wafer 130 which is a silicon wafer and serves as a plurality of protective substrates 30 is attached to the piezoelectric element 300 side of the flow path forming substrate wafer 110 with an adhesive 35 (FIG. 2). After joining via (b), the flow path forming substrate wafer 110 is thinned to a predetermined thickness.

  Next, as shown in FIG. 8B, a mask film 53 is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, as shown in FIG. 8C, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) using an alkaline solution such as KOH through the mask film 53, thereby forming the piezoelectric element 300. Corresponding pressure generating chambers 12, ink supply passages 13, communication passages 14, communication portions 15 and the like are formed.

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

  Thus, in this embodiment, the piezoelectric layer 70 can be easily patterned by wet etching while suppressing side etching.

  In the above-described embodiment, the heat treatment for removing the plasma treatment layer 75 is performed after the second electrode is formed. However, the present invention is not limited to this. It may be performed after wet etching, for example, before the second electrode 80 is formed.

  In the present embodiment, the plasma treatment is performed over the entire surface of the piezoelectric layer 70, but the present invention is not limited to this. Since the side etching can be effectively suppressed if the plasma treatment is performed at least in the vicinity of the boundary line of the region where the resist film 78 is provided, the region where the resist film 78 is provided by providing a mask during the plasma processing. The plasma processing may be performed only in the vicinity of the boundary line. With this configuration, it is possible to minimize the change in characteristics of the piezoelectric layer 70 while effectively suppressing side etching. Note that in the case where the plasma treatment is performed only in the vicinity of the boundary line of the region where the resist film 78 is provided in this way, the heat treatment for removing the plasma treatment layer 75 may not be performed.

(Embodiment 2)
In the present embodiment, another method for manufacturing an ink jet recording head will be described. In the ink jet recording head of this embodiment, the first electrode is common to each piezoelectric element, and the second electrode is provided for each piezoelectric element, that is, individually. A method for manufacturing such an ink jet recording head will be described with reference to FIGS.

  First, as shown in FIG. 9A, the first electrode 60 is formed on the insulator film 52 as in the first embodiment. Next, the piezoelectric layer 70 made of the piezoelectric film 74 is formed on the first electrode 60.

  As shown in FIG. 9B, a second electrode film 81 is formed on the surface of the piezoelectric layer 70 by sputtering or the like. The second electrode film 81 can be formed in the same manner as the second electrode in the first embodiment.

  Next, as shown in FIG. 9C, an electrode mask 82 is formed on the surface of the second electrode film 81, and the second electrode 80 is patterned by dry etching. Accordingly, the piezoelectric layer 70 is exposed between the second electrodes 80.

In this case, dry etching introduces chlorine gas and argon gas as the etching gas, and discharges with a discharge power of 500 to 1800 W (1000 W in this embodiment), and a bias power of 250 to 500 W (450 W in this embodiment). ) To apply a bias voltage. In addition, boron trichloride (BCl ₃ ) and fluorine carbide (CF ₄ , C4F _8, etc.) can be used as the etching gas.

  Next, as shown in FIG. 10A, plasma processing is performed on the exposed surface of the piezoelectric layer 70 to form a plasma processing layer 75 by continuously performing dry etching and over-etching as it is. That is, in this embodiment, the plasma treatment of the surface of the piezoelectric layer 70 is performed by dry etching for patterning the second electrode 80.

  As shown in FIG. 10B, a piezoelectric layer resist film 83 is provided so as to cover the electrode mask 82. The piezoelectric layer resist film 83 can be formed in the same manner as the resist film in the first embodiment.

  With this piezoelectric layer resist film 83 as a mask, wet etching is performed to pattern the piezoelectric layer 70. The wet etching can also be performed in the same manner as the wet etching in the first embodiment.

  Next, as shown in FIG. 10C, the piezoelectric layer resist film 83 is removed. Thereafter, a heating process is first performed to remove the plasma treatment layer 75 formed on the surface of the piezoelectric layer 70. The heating step can also be performed in the same manner as the heating step in the first embodiment. Thereafter, as in Embodiment 1, individual ink jet recording heads are formed from the flow path forming substrate wafer 110 having the piezoelectric elements 300 described above.

  As described above, also in this embodiment, by forming the plasma processing layer 75 on the piezoelectric layer 70, side etching can be suppressed when the piezoelectric layer 70 is wet-etched, and microfabrication can be easily performed by wet etching. It is possible to perform with high throughput. In this case, manufacturing can be performed more easily by simultaneously performing dry etching of the second electrode without separately providing a plasma processing step. Note that the discharge may be stopped once after the second electrode is patterned, and plasma treatment as shown in Embodiment 1 may be performed again. That is, the plasma treatment may be performed under a condition different from the case where the second electrode is patterned by introducing a different plasma generation gas.

  In this case, also in this embodiment, since the plasma treatment layer 75 can be removed by the heating process, a change in the displacement characteristics of the piezoelectric layer 70 can be suppressed.

Hereinafter, the present invention will be described in more detail with reference to experimental examples.
(Experimental example 1)
A piezoelectric film made of BFO was formed with a thickness of 0.8 μm. For this piezoelectric film, chlorine and argon were introduced as plasma generation gases (each gas flow rate was 50 sccm), and plasma treatment was performed for 10 seconds with a chamber pressure of 1.0 Pa, a discharge power of 900 W, and a bias power of 400 W. Next, a resist film made of a novolak resin was formed by a known method and patterned. Using this resist film as a mask, the piezoelectric film was wet etched with a mixed solution of hydrochloric acid and nitric acid as a wet etching solution. A cross-sectional SEM photograph near the resist is shown in FIG.

(Experimental example 2)
A piezoelectric film was formed in the same manner as in Experimental Example 1 except that plasma treatment was not performed, and wet etching was performed. A cross-sectional SEM photograph in the vicinity of the resist is shown in FIG.

  From each SEM photograph showing the results of these experimental examples 1 and 2, the side etching amount is 0.7 μm in the case of experimental example 1 in which the plasma treatment is performed, and in the case of experimental example 2 in which the plasma treatment is not performed. The side etching amount was 4.6 μm. Therefore, the side etching amount in Experimental Example 1 in which the plasma treatment was performed was about 15% based on the side etching amount in Experimental Example 2 in which the plasma processing was not performed.

  From Experimental Examples 1 and 2, it was found that side etching can be suppressed by performing plasma treatment without optimizing the wet etching solution.

(Experimental example 3)
A piezoelectric film made of PZT was formed with a thickness of 0.8 μm. For this piezoelectric film, only chlorine gas was introduced as a plasma generation gas (flow rate 100 sccm), and plasma treatment was performed for 15 seconds with a chamber internal pressure of 0.5 Pa, a discharge power of 1000 W, and a bias power of 100 W.
Next, a resist film made of a novolak resin was formed by a known method and patterned. Using this resist film as a mask, the piezoelectric film was used as a wet etching solution and wet etching was performed using a mixed solution mainly composed of hydrochloric acid and hydrofluoric acid, and the side etching amount was examined. The side etching amount is 62% based on the side etching amount when the plasma treatment is not performed, and it was confirmed that the side etching can be suppressed by the plasma treatment. That is, a mixed liquid mainly composed of hydrochloric acid and hydrofluoric acid as a wet etching liquid is usually optimized as a wet etching liquid for PZT, but such a wet etching liquid is further subjected to side etching by plasma treatment. Could be suppressed.

(Experimental example 4)
The side etching amount is the same as in Experimental Example 3 except that only oxygen gas is introduced as the plasma generation gas (flow rate 100 sccm), the chamber pressure is 0.5 Pa, the discharge power is 1000 W, and the bias power is 100 W. Examined. The amount of site etching obtained is 73% based on the amount of side etching in Example 2 when the amount of side etching without plasma treatment is used as a reference, and the side etching can be suppressed by plasma treatment. Was confirmed. Thus, it has been found that oxygen gas has an effect of suppressing side etching next to chlorine gas.

(Experimental example 5)
It is the same as Experimental Example 3 except that only carbon tetrafluoride gas is introduced as the plasma generation gas (flow rate 100 sccm), and the plasma treatment is performed for 15 seconds with a chamber internal pressure of 0.5 Pa, a discharge power of 1000 W, and a bias power of 100 W. The etching amount was examined. The obtained side etching amount was 79% based on the side etching amount when the plasma treatment was not performed, and it was confirmed that the side etching can be suppressed by the plasma treatment.

(Experimental example 6)
The side etching amount is the same as in Experimental Example 3 except that only argon gas is introduced as the plasma generation gas (flow rate: 100 sccm), the chamber pressure is 0.5 Pa, the discharge power is 1000 W, and the bias power is 100 W. Examined. The obtained side etching amount was 87% based on the side etching amount when the plasma treatment was not performed, and it was confirmed that the side etching can be suppressed by the plasma treatment.

(Experimental example 7)
The side etching amount was examined in the same manner as in Experimental Example 4 except that the plasma treatment was performed for 15 seconds without applying bias power. The obtained site etching amount was 88% based on the side etching amount when the plasma treatment was not performed, and it was confirmed that the side etching can be suppressed by the plasma treatment. It was also found that it is preferable to have a bias power.

(Experimental example 8)
The side etching amount was examined in the same manner as in Experimental Example 3 except that the plasma treatment was performed for 15 seconds without applying bias power. The obtained site etching amount was 92% based on the side etching amount when the plasma treatment was not performed, and it was confirmed that the side etching can be suppressed by the plasma treatment. It was also found that it is preferable to have a bias power.

  From the above experimental examples, it was confirmed that side etching can be suppressed by plasma treatment.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above.

  For example, the ink jet recording head I is mounted on an ink jet recording apparatus II, for example, as shown in FIG. A recording head unit 1 having an ink jet recording head I is provided with a cartridge 2 constituting an ink supply means in a detachable manner. A carriage 3 on which the recording head unit 1 is mounted is a carriage shaft 5 attached to an apparatus body 4. Are provided so as to be movable in the axial direction. The recording head unit 1 ejects, for example, a black ink composition and a color ink composition.

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

  In the present invention, it is possible to make the ejection characteristics uniform while suppressing the breakage of the piezoelectric element 300 constituting the ink jet recording head I as described above. As a result, it is possible to realize an ink jet recording apparatus II with improved printing quality and improved durability.

  In the above-described example, the ink jet recording apparatus II has been exemplified in which the ink jet recording head I is mounted on the carriage 3 and moves in the main scanning direction, but the configuration is not particularly limited. The ink jet recording apparatus II may be, for example, a so-called line recording apparatus that performs printing by fixing the ink jet recording head I and moving a recording sheet S such as paper in the sub-scanning direction.

  In the above-described embodiment, the present invention has been described by taking an ink jet recording head as an example of a liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads. Examples of the liquid ejecting head include various recording heads used in image recording apparatuses such as printers, color material ejecting heads used for manufacturing 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.

  Furthermore, the present invention can be applied not only to such a liquid jet head (inkjet recording head) but also to an actuator device mounted on any device. The actuator device using the piezoelectric element manufactured according to the present invention can be applied to various sensors such as an ultrasonic transducer and a pyroelectric sensor.

  I ink jet recording head (liquid ejecting head), II ink jet recording apparatus (liquid ejecting apparatus), 10 flow path forming substrate, 11 partition, 12 pressure generating chamber, 13 ink supply path, 14 communication path, 15 communication section, 20 Nozzle plate, 21 Nozzle opening, 30 Protection substrate, 31 Piezoelectric element holding portion, 32 Manifold portion, 33 Through hole, 35 Adhesive, 40 Compliance substrate, 41 Sealing film, 42 Fixing plate, 43 Opening portion, 50 Vibration plate, 51 elastic film, 52 insulator film, 60 first electrode, 70 piezoelectric layer, 71 recess, 73 piezoelectric precursor film, 74 piezoelectric film, 75 plasma treatment film, 80 second electrode, 90 lead electrode, 100 manifold , 300 piezoelectric element, 320 active part

Claims (9)

Manufacturing of a liquid ejecting head comprising a flow path forming substrate provided with a liquid flow path communicating with a nozzle opening for discharging a liquid, and a piezoelectric element provided on the flow path forming substrate and applying pressure to the liquid flow path A method,
Forming a piezoelectric film made of a piezoelectric body of the piezoelectric element;
Performing a plasma treatment on a predetermined position of the piezoelectric film;
And a step of patterning the piezoelectric film by wet etching. The method of manufacturing a liquid jet head according to claim 1, wherein a bias voltage is applied to the piezoelectric film during the plasma processing. The piezoelectric film is made of a metal oxide,
3. The method of manufacturing a liquid jet head according to claim 1, wherein the gas introduced in the plasma processing is a gas containing oxygen. The method of manufacturing a liquid jet head according to claim 1, further comprising a step of heating the piezoelectric film after the wet etching. 5. The method of manufacturing a liquid jet head according to claim 1, wherein the piezoelectric film is made of any one of lead zirconate titanate, barium titanate, and iron titanate. The method for manufacturing a liquid jet head according to claim 1, wherein the wet etching solution used for the wet etching contains at least one of hydrochloric acid, nitric acid, and hydrofluoric acid. The method of manufacturing a liquid jet head according to claim 1, wherein the predetermined position is near a region where a mask is provided when the wet etching of the piezoelectric film is performed. The method of manufacturing a liquid jet head according to claim 1, wherein a mask provided when performing the wet etching is made of an organic material. A method for manufacturing a piezoelectric element comprising: a piezoelectric film made of a piezoelectric body; and a first electrode and a second electrode provided on both sides of the piezoelectric film,
Forming the piezoelectric film;
Performing a plasma treatment on a predetermined position of the piezoelectric film;
And a step of patterning the piezoelectric film by wet etching.