JP2006069204A - Process for manufacturing liquid ejection head and process for manufacturing substrate for liquid ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To meet the demand not only of a piezoelectric element structure exhibiting excellent durability and piezoelectric characteristics, but also of manufacturing a high definition inkjet recording head arranged with nozzles at high density inexpensively with high yield in which machining of liqud chamber is simplified. <P>SOLUTION: In the inkjet recording head where a vibrating plate and a piezoelectric element for ejecting ink are formed in an ink channel structure having a pressure generating chamber connected with an ink sump through a communication hole, the piezoelectric element is formed on a single crystal silicon film formed on an Si substrate through an insulating film, and the single crystal silicon film is exposed on the side facing the back space of the vibrating plate of the piezoelectric element through the insulating film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a liquid discharge head that discharges liquid by applying energy to the liquid from the outside (hereinafter also referred to as “inkjet recording head”) and a method for manufacturing a substrate for a liquid discharge head.

  Printers using an ink jet recording apparatus as a printing apparatus for personal computers are widely used because of their good printing performance and low cost. Inkjet recording devices generate bubbles in ink by thermal energy, eject ink droplets by pressure waves caused by the bubbles, suck ink droplets by electrostatic force, pressure waves by a vibrator such as a piezoelectric element. The one using is developed.

  Among the above-described ink jet recording apparatuses, those using piezoelectric elements are provided with an ink flow path communicating with an ink discharge port, a pressure generation chamber communicating with the ink flow path, and the pressure generation chamber. When a predetermined voltage is applied to the bonded diaphragm film piezoelectric thin film, the piezoelectric thin film expands and contracts, causing the piezoelectric thin film and the diaphragm film to integrally vibrate and compress the ink in the pressure generating chamber. Thus, the ink droplet is ejected from the ink ejection port.

  When the piezoelectric thin film is formed with a single crystal or preferentially oriented, a large displacement can be obtained and the displacement can be controlled linearly according to the drive waveform. Japanese Laid-Open Patent Publication No. 10-181016 discloses a method in which a piezoelectric body is formed on a single crystal substrate by single crystal or dominant orientation, and then the substrate is removed and transferred onto a vibration plate.

  In addition, by reducing the thickness of the piezoelectric film and the diaphragm constituting the piezoelectric element, a piezoelectric element structure that enables fine processing generally used in a semiconductor process and has excellent durability and piezoelectric characteristics, It is disclosed in Japanese Patent Application Laid-Open No. 2002-234156. Japanese Patent Application Laid-Open No. 2002-234156 discloses a method of forming a piezoelectric thin film on a so-called SOI substrate in which an Si single crystal is stacked on an oxide film by single crystal or dominant orientation.

  In recent years, inkjet recording heads are applied not only to consumer printers that print text or image information on paper, but also to fields where organic materials (red, blue, green) have been applied to substrates using pattern paper, etc. Use in an industrial field such as organic EL (Electro Luminescence) has been studied.

  When used in the industrial field, the throughput per hour is a parameter that is directly related to cost, so the inkjet recording head has the high speed required by consumer printers and the ability to eject fine droplets. At the same time, durability and reliability are required.

  Japanese Patent Application Laid-Open No. 10-181016 discloses a single crystal having a perovskite structure mainly composed of lead zirconate titanate or barium titanate on a single crystal substrate that is not directly bonded to the diaphragm, or preferential orientation in the polarization direction. The thin film was grown, and then the substrate was removed and bonded to the diaphragm. For this reason, it has been difficult to produce an inkjet recording head having a high-definition nozzle arrangement.

  In addition, the process disclosed in Japanese Patent Application Laid-Open No. 2002-234156 can achieve a piezoelectric element structure that can be finely processed and has excellent durability and piezoelectric characteristics. Therefore, it is desired to produce an ink jet recording head which is inexpensive and has a high yield and a high definition and has nozzles arranged at a high density.

As is clear from the above description, the ink jet recording head used in this specification does not mean only a head of a type that ejects ink onto paper, but on an object in which liquid is disposed at a desired position. It is used as a general term for the type of head that discharges to the head.
Japanese Patent Laid-Open No. 10-181016 JP 2002-234156 A Japanese Patent Laid-Open No. 10-181016

  One of the objects of the present invention is to provide a manufacturing method capable of obtaining a high-density piezoelectric element drive type ink jet recording head by a simple process.

  Another object of the present invention is to provide a pressure generating chamber communicating with a discharge port for discharging a liquid, a piezoelectric material film provided in correspondence with the pressure generating chamber, and a pair of electrode films sandwiching the piezoelectric material film. A step of preparing a structure in which a single crystal Si layer is laminated on the surface of a Si substrate via an etching stop layer; and the single crystal Si. A step of forming a buffer layer on the layer, and a step of forming the piezoelectric material film comprising a single crystal thin film or a thin film preferentially oriented in the polarization direction on one of the pair of electrode films on the buffer layer; A step of forming the pressure generating chamber on the piezoelectric material film, and a step of etching a portion corresponding to the piezoelectric material film of the Si substrate from the back surface side of the Si substrate until reaching the etching stop layer. Have Is to provide a method of manufacturing a liquid discharge head characterized by and.

  Still another object of the present invention is a method of manufacturing a substrate for a liquid discharge head having a piezoelectric element including a piezoelectric material film and a pair of electrode films sandwiching the piezoelectric material film, and etching the surface of a Si substrate. A step of preparing a structure in which a single crystal Si layer is stacked via a stop layer, a step of forming a buffer layer on the single crystal Si layer, and one of the electrode films on the buffer layer. Forming the piezoelectric material film comprising a single crystal thin film or a thin film preferentially oriented in the polarization direction, and reaching the etching stop layer at a position corresponding to the piezoelectric material film of the Si substrate from the back side of the Si substrate. And a step of etching until the liquid discharge head substrate is manufactured.

  As described above, according to the present invention, it is possible to obtain a high-density piezoelectric element driving type ink jet recording head with a simple process. By using this, it is possible to provide an ink jet recording head having high applicability to ink types and capable of high-quality printing.

  The present invention relates to an ink jet recording head in which a vibration plate for ejecting ink and a piezoelectric element are formed on an ink flow path structure including a pressure generating chamber connected to an ink reservoir through a communication hole. It is formed on a single crystal silicon film formed on a substrate via an insulating film, and the single crystal silicon film is exposed via the insulating film on the side facing the rear space of the diaphragm of the piezoelectric element. The ink jet recording head is characterized. Piezoelectric elements have a perovskite structure mainly composed of lead zirconate titanate, relaxor or barium titanate based on a buffer layer and a crystalline electrode on a single crystal silicon film, or prioritize the polarization direction. An oriented thin film is preferred.

  The diaphragm includes at least a silicon layer and an insulating film, and the insulating film is preferably a silicon nitride film.

  Furthermore, the plane orientation of the single crystal Si layer on which the piezoelectric element is formed is preferably (100), and the Si substrate is preferably a substrate having a plane orientation of (110).

  The buffer layer is preferably a film containing at least yttrium-stabilized zirconia (YSZ).

  When the ink jet recording head has a plurality of pressure generating chambers, it is preferably formed in parallel to the (111) plane of the silicon substrate and continuously formed in a direction of 90 degrees with the (111) plane of the silicon substrate. .

  Further, the present invention includes a step of forming an insulating film serving as at least an etching stopper film on the surface of the silicon substrate, a step of forming an etching protective film on the back surface of the silicon substrate, a step of bonding a single crystal Si layer, A step of laminating a buffer layer on the single crystal Si layer, a step of forming a first electrode film, a step of forming a piezoelectric element thin film thereon, and a second electrode film on the piezoelectric element film Forming the diaphragm, forming the diaphragm, removing the etching protective film from the portion corresponding to the diaphragm on the back surface of the substrate and the portion corresponding to the ink supply port to form an opening, and etching from the opening Etching the substrate to the stopper layer, and removing the etching stopper layer at the opening corresponding to the ink supply port to form an ink supply port. A method for producing an ink jet recording head is characterized.

  In the ink jet recording head of the present invention, after the diaphragm is formed, a step of forming a first pattern serving as a mold material of the pressure generating chamber with a soluble resin on the silicon substrate, a step of forming a conductive layer, and the conductive layer Forming a second pattern to be a mold material for the discharge port with a soluble resin on the layer; forming a plating layer on the conductive layer by a plating process; removing the second pattern; Removing one pattern.

  A sacrificial layer may be provided on the silicon substrate at portions corresponding to the diaphragm opening and the ink supply port.

  The present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic sectional view of an ink jet recording head showing an embodiment of the present invention. A Si wafer is used as the substrate. On a Si substrate, Si ₃ N ₄ film 103, SiO ₂ film 104, Si single crystal layer 105, buffer layer (YSZ: yttrium stabilized zirconia) 106, electrode, single crystal or orientation piezoelectric film (piezoelectric material film), An electrode (electrode film) and a diaphragm 109 are sequentially formed.

  The silicon substrate 101 is provided with a through hole serving as a hole 107 and an ink supply port 108 for supplying ink from the back surface by etching to form a space on the back surface of the diaphragm.

  A vibration plate 109, a piezoelectric thin film 110, an upper electrode 111, a lower electrode 112, a protective film 113, and the like are formed above the hole 107 of the Si substrate.

  An individual pressure generating chamber 114 is formed on the substrate. As the material of the individual pressure generating chamber 114, resin, photosensitive resin, metal, ceramic, or the like can be applied. A communication hole 115 provided at the right end of the individual pressure generating chamber 114 is connected to a common liquid chamber (not shown).

  An ink discharge port 116 is formed at the left end of the individual pressure generating chamber 114, and ink pushed out by deformation of the diaphragm is discharged through the path 117 and printed on the medium.

  FIG. 2 is a top view of the substrate. (Electrodes and the like are omitted) Adjacent pressure generating chambers are arranged in parallel. FIG. 3 is a rear view. The diaphragm back space 107 and the ink supply port 108 are formed by etching.

Next, the manufacturing process of the ink jet recording head of this embodiment will be described step by step using the process cross-sectional views of FIGS.
(1) Using a high-density plasma etching apparatus (ICP) on a silicon substrate 101 having a substrate surface orientation (110), each side is parallel to a surface equivalent to the (111) surface, as shown in FIG. The concave portion of the parallelogram corresponding to the diaphragm back space 107 and the ink supply port 108 having a narrow angle of 70.5 degrees is formed.
(2) The sacrificial layer 102 in which the recesses are filled by depositing and polishing polysilicon or amorphous silicon by LPCVD or the like on the surface of the silicon substrate 101 where at least the parallelogram recesses are formed. (See FIG. 4A).

When the substrate is anisotropically etched to reach the sacrificial layer 102 made of polysilicon, the etching speed of polysilicon is faster than that of crystalline silicon on the substrate, so that the substrate is quickly removed by etching. Even when the thickness of the substrate varies, the supply port can be formed with high accuracy because the sacrificial layer 513 is removed by etching as soon as it is exposed. In this embodiment, polysilicon or amorphous silicon is used as the material for the sacrificial layer 513, but any material can be used as long as it has a higher etching rate than crystalline silicon such as Al (aluminum). (3) After the Si ₃ N ₄ film 103 having a thickness of 100 to 400 nm is formed by the CVD method on the surface of the silicon substrate 101 on which at least the parallelogram-shaped recesses are formed, the thickness is similarly 100 to 100 by the CVD method. A 400 nm SiO ₂ film 104 is formed on both sides of the silicon substrate 101 (see FIG. 4B).

Needless to say, a Si ₃ N ₄ single layer film having a thickness of 100 to 400 nm may be formed.

It should be noted that the Si ₃ N ₄ film has a function as an etching stopper film (etching stop layer) when wet etching a substrate described later, and the composition ratio of silicon and nitrogen is not exactly 3: 4. Needless to say, an oxynitride film may be used.
(4) A single crystal Si substrate having a plane orientation (100) is bonded to this substrate at a high temperature, and the single crystal Si layer 105 is polished to a thickness of 1 to 5 μm. Another method may be used to bond the single crystal silicon layers (see FIG. 4C).

The reason why the plane orientation is a (100) single crystal silicon layer is to grow a piezoelectric / electrostrictive film in a single crystal.
(5) A buffer layer made of a 10 nm thick YSZ film 106 is deposited by a high-temperature sputtering method under a substrate temperature of 600 to 900 ° C. and in an Ar / O ₂ atmosphere (see FIG. 4 (4)).

As the buffer layer, a metal oxide represented by ZrO ₂ , CeO ₂ , or SrTiO ₃ is preferably used, and ZrO ₂ is preferable.

As the ink jet head, a material containing rare earth metal elements including Sc, Y and Pr in ZrO ₂ is more preferable. For example, the thing containing Y is preferable. In order to control the crystal as a single crystal film and a single orientation film, the piezoelectric film is a YSZ-based material represented by the formula (Y ₂ O ₃ ) _x (ZrO ₂ ) _1-x containing Y (where x is 0.01 to 0.2) is a preferred buffer layer.
(6) In accordance with the sacrificial layer 102 that forms the back of the diaphragm, a metal film that forms the lower layer electrode 112 is formed of a metal that can maintain a crystallinity such as Pt at 400 to 800 ° C. and can withstand high temperatures. .

  As the electrode material, a metal material or a conductive metal oxide can be used. As the metal material, a face-centered cubic material, a body-centered cubic material, or a hexagonal close-packed structure material can be used, but a face-centered cubic material is preferable, for example, Pt, Ir, Pd, Rh, Ag, Al Au, Cu, Ni, etc. are preferably used, and Pt and Ir are more preferable.

On the other hand, a conductive metal oxide can also be used as an electrode. As the conductive metal oxide, a perovskite oxide conductive material can be selected and used. Examples of perovskite-based oxides are compounds represented by the formula La _1-x Sr _x VO ₃ , 0.23 <x ≦ 1, Gd _1-x Sr _x VO ₃ , 0.4 <x <0 .5, a compound represented by La _1-x Sr _x CoO ₃ , a compound represented by 0 <x <1, a compound represented by Ca _1-x Sr _x RuO ₃ and 0 <x <1, (Ba, Ca , Sr) represented by TiO _3-x, compound is _{x ≠ 0, SrRuO 3, CaRuO} 3, BaPbO 3, La 2 SrCu 2 VO 6.2, SrCrO 3, LaNiO 3, LaCuO 3, BaRuO 3, SrMoO 3, CaMoO 3 BaMoO ₃ , SrIrO _3, etc., and SrRuO ₃ , LaNiO ₃ , BaPbO ₃ , and CaRuO ₃ are preferable.
(7) A piezoelectric element comprising a single crystal having a perovskite structure mainly composed of lead zirconate titanate or barium titanate as a main component on the lower electrode 112 or a thin film preferentially oriented in the polarization direction by a method such as sputtering or CVD. A film 110 is formed.

  The film formation at this time may be performed by heating at 400 to 700 ° C., or baking at 400 to 800 ° C. after film formation at a low temperature.

The piezoelectric / electrostrictive film of the present invention means a piezoelectric film and / or an electrostrictive film. Examples of the material used for the piezoelectric / electrostrictive film include perovskite compounds. For example, an electrostrictive material of the piezoelectric material and a relaxor material such as lead zirconate titanate _{PZT [Pb (Zr x Ti 1} -x) O 3] or barium titanate BaTiO _3. An xB of lead zirconate titanate (PZT) is preferably an MPB (morphotropic phase boundary) composition of 0.40 to 0.65, but other composition ratios may be used. The crystal structure of PZT may be either tetragonal or rhombohedral. BaTiO ₃ is preferably a tetragonal (001) -oriented film. BaTiO ₃ may contain a trace amount of lead, bismuth, Fe, and potassium.

The following can be selected as the electrostrictive material used in the present invention. For _{example, PMN [Pb (Mg x Nb} 1-x) O 3], PNN [Pb (Nb x Ni 1-x) O 3], PSN [Pb (Sc x Nb 1-x) O 3], PZN [Pb _{(Zn x Nb 1-x)} O 3], PMN-PT ((1-y) [Pb (Mg x Nb 1-x) O 3] - y [PbTiO 3]), PSN-PT ((1-y _{) [Pb (Sc x Nb 1} -x) O 3] - y [PbTiO 3]), PZN-PT ((1-y) [Pb (Zn x Nb 1-x) O 3] - y [PbTiO 3] ), LN [LiNbO ₃ ], KN [KNbO ₃ ]. Here, x and y are numbers of 1 or less and 0 or more. For example, in the case of PMN, x is 0.2 to 0.5, and in PSN, x is preferably 0.4 to 0.7, y of PMN-PT is 0.2 to 0.4, and y of PSN-PT is 0.35-0.5, y of PZN-PT is preferably 0.03-0.35. Further, PMN-PZT, PZN-PZT, PNN-PZT, and PSN-PZT compounds in which Zr is substituted for Ti in PMN-PT, PZN-PT, PNN-PT, and PSN-PT may be used.

The piezoelectric / electrostrictive film may have a single composition or a combination of two or more. Moreover, the composition which doped the trace amount element to the said main component may be sufficient. The piezoelectric / electrostrictive film of the present invention is preferably crystal-controlled in order to exhibit excellent piezoelectricity, and preferably has a specific orientation of a specific crystal structure of 50% or more by X-ray diffraction. Is more preferably 90% or more.
(8) A laminated film of a metal such as Pt / Ti is formed as an electrode on the piezoelectric body, and then a laminated film of a metal such as Pt / Ti and a piezoelectric element film using a photoresist using a photolithography method as a mask 110 is removed by etching and a piezoelectric element having a desired shape is generated.

In the dry etching used at this time, a known condition was used for etching the metal such as Pt / Ti and the piezoelectric element film. For example, the Pt / Ti etching was performed by RIE (reactive ion etching) using a mixed gas of Cl ₂ and BCl ₃ .

  If the dry etching conditions are such that the etching selectivity between the metal constituting the lower electrode and the piezoelectric element film can be taken, the metal constituting the lower electrode is hardly etched even if overetching is performed after etching the piezoelectric element film. . Thereafter, similarly, a photolithography method is used to form a lower electrode 112 having a desired shape using a photoresist as a mask (see FIG. 4 (5)).

For dry etching, known etching conditions were used.
(9) A SiN _x or SiO _x film is deposited on the formed piezoelectric element portion using plasma CVD or the like to form the diaphragm 113 (see Example 2 described later), or as in this example Alternatively, the SiN _x or SiO _x film on the piezoelectric element portion can be thinly formed, and the lower Si single crystal film 105 can be used as a vibration plate as a simple protective film 113 (see FIG. 5A).
(10) Photoresist in which the protective film 113, the buffer layer 106, the single crystal silicon layer 105, and the Si ₃ N ₄ film 103 are formed by photolithography using an opening which is a part of the communication hole 115 connected to the ink supply port. Is formed by carrying out normal dry etching (see FIG. 5B).

Etching of silicon nitride films such as single crystal silicon and Si ₃ N ₄ film is a well-known method for producing ordinary silicon semiconductors, and therefore the etching conditions are omitted.
(11) After that, a first pattern 118 is formed as a mold material for forming a pressure generating chamber or the like by removing (see FIG. 5 (3)). As a formation method, a printing method or a photolithography method can be used, but a photolithography method using a photosensitive resin is preferable because a fine pattern can be formed.

  As the mold material, it is possible to pattern a thick film, which can be removed later with an alkaline solution or an organic solvent. Therefore, as the mold material, the THB series (manufactured by JSR) or the PMER series (manufactured by Tokyo Ohka Kogyo) can be used. .

In the examples to be described later, the product name: PMER HM-3000 manufactured by Tokyo Ohka Kogyo Co., Ltd. is used, but the present invention is not limited to this. The film thickness is preferably 60 μm or less for a single coating and 90 μm or less for a plurality of coatings from the viewpoint of film thickness distribution and patterning properties.
(12) A conductive layer 119 serving as a plating seed layer is formed on the first pattern by sputtering or the like (FIG. 5 (4)). As the conductive layer, Pt, Au, Cu, Ni, Ti, or the like can be used. Since a fine pattern cannot be formed unless the adhesion between the resin described later and the conductive layer is good to some extent, a laminated structure in which Pt, Au, Cu, Ni, etc. are formed after forming another metal film It can also be. Since it is necessary to remove the portion of the conductive layer corresponding to the discharge port in the step of removing the mold material described later, the upper limit of the thickness of the conductive layer is preferably 150 nm or less, and more preferably 100 nm or less. If it is thicker than 150 nm, the conductive layer corresponding to the discharge port may not be completely removed in the step of removing the mold material. The lower limit of the thickness of the conductive layer is preferably 10 nm or more. If the thickness of the conductive layer is 10 nm or more, the growth of plating is not hindered.
(13) A second pattern (discharge port type material resist 120) to be a discharge port is formed by removing the conductive layer on the first pattern later (see FIG. 6A). As the mold material, THB series (manufactured by JSR), PMER series (manufactured by Tokyo Ohka Kogyo Co., Ltd.) and the like can be used. In this embodiment, PMER LA-900PM is used. However, the present invention is not limited to this, and any film can be used as long as a thick film can be patterned and later removed with an alkaline solution or an organic solvent. The film thickness is preferably 30 μm or less because the patterning accuracy is more required than the first pattern. That is, the total of the first pattern and the second pattern is preferably 120 μm or less.

In order to efficiently use the force generated in the pressure generation chamber as the discharge force, it is preferable that the upper surface of each of the first pattern and the second pattern has a smaller taper than the lower surface. An optimum shape can be obtained by using a simulation or the like. There are various methods for forming the taper, but in the case of a proximity type exposure machine, it is possible to increase the distance (gap) between the substrate and the mask. It is also possible to use a gray scale mask. Of course, if reduced exposure such as 1/5 or 1/10 is used, it is easy to form minute discharge ports. Furthermore, if a gray scale mask is used, it is easy to form a complicated shape such as a spiral shape instead of a simple tapered shape.
(14) The flow path structure 114 including the pressure generation chamber / discharge port is formed by plating (see FIG. 6B). Types of plating include electroplating and electroless plating, which can be used alone or in combination. Electroplating has the advantage that the treatment liquid is inexpensive and the waste liquid treatment is simple, and the electroless plating has good advantages, can form a uniform film, and the plating film is hard and wear-resistant. is there.

  As a method of combining electroplating and electroless plating, for example, there is a method of first forming a thick Ni layer by electroplating and then forming a thin Ni-PTFE composite plating layer by electroless plating. In the case of this method, there is an advantage that a plating layer having a film having a desired characteristic can be formed at low cost.

  Examples of the plating include single metal plating such as Cu, Ni, Cr, Zn, Sn, Ag, and Au, alloy plating, and composite plating that deposits PTFE. Ni is preferably used because of its chemical resistance and strength. Further, as described above, Ni-PTFE composite plating or the like can be used for finishing the plating process in order to impart water repellency to the plating film.

When plating is performed on the substrate, it is preferable to form a photoresist serving as a protective film for plating using, for example, a photolithography method in the die cutting region.
(15) In order to protect the surface side of the silicon substrate 101 prepared in the previous step from the etchant, a resin (etching protection film 121) that has alkali resistance and can be removed later with an organic solvent or the like is applied to the substrate surface, and silicon The SiO ₂ film 104 at a position where the opening on the back surface of the substrate 101 is to be formed is removed (see FIG. 6 (3)). The substrate may be mounted on a jig that can be brought into contact with the etchant only on the back side.

  A leading hole 122 by laser processing or the like may be formed in the vicinity of the narrow portion of the parallelogram at the boundary corresponding to the back space 107 of the diaphragm in FIG. 1 on the back surface (see FIG. 7 (1)). This suppresses a plane equivalent to the oblique (111) plane generated from the narrow angle of the parallelogram during anisotropic etching. It is preferable that the leading hole is as close as possible to the etching stop layer. The depth of the leading hole is generally 60% or more of the substrate thickness, preferably 70% or more, and optimally 80% or more. Of course, it must not penetrate the substrate.

  If this substrate is immersed in an etchant and anisotropic etching is performed so that a surface equivalent to the (111) plane appears on the side surface, a free space having a parallelogram shape and an ink supply port can be formed (FIG. 7). (See (2)). Examples of the alkaline etchant include KOH and TMAH (tetramethylammonium hydroxide). TMAH is preferably used from the viewpoint of the environment.

After the etching, the alkali-resistant protective film 121 is removed with an organic solvent or the like (see FIG. 7 (3)).
(16) Next, the SiN layer, which is an etching stop layer using an alkaline etchant, is removed using dry etching or the like.
(17) The first pattern and the second pattern (discharge port mold material resist 120), which are the mold material of the flow path structure including the pressure generating chamber / discharge port, are removed with an alkaline solution or an organic solvent.
(18) After the second pattern (discharge port type material resist 120) is removed, the plating seed layer 119 exposed at the bottom of the opening is etched away using, for example, a dry etching method using the individual pressure generation chamber wall 114 as a mask. To do.

Thereafter, the substrate can be cut to obtain an ink jet recording head die. The steps (1) to (16) are not limited to this, and it is also possible to open a through hole on the back surface with ICP without using anisotropic etching. In this case, the first step of filling the sacrificial layer 102 becomes unnecessary. The etching stop layer can also be selected from either a Si ₃ N ₄ single layer film or a stacked layer of SiO ₂ and Si ₃ N ₄ .

  In addition, the formation of the seed for plating may be performed by changing the location of the seed and the manufacturing procedure.

  The ink jet recording head of the present invention may take a form in which a plurality of pressure generating chambers are connected to the ink reservoirs through the communication holes, or an ink jet unit in which the pressure generating chambers are connected to the ink reservoirs through the communication holes. Needless to say, it is possible to adopt a form in which a plurality of layers are provided.

<Example 1>
FIG. 1 is a schematic sectional view of an ink jet recording head showing an embodiment according to the present invention. A Si substrate 101 having a plane orientation (110) of 635 μm in thickness was used as the substrate.

On Si substrate 101, Si ₃ N ₄ film 103 is 300 nm by LPCVD, SiO ₂ film 104 is 200 nm by CVD, Si single crystal layer 105 is formed by bonding and polishing to 2 μm, and YSZ film is formed as buffer layer 105 by sputtering. 10 nm deposited, Pt deposited as electrode 112 by 150 nm sputtering, single crystal lead zirconate titanate (PZT) 110 deposited by 2 μm sputtering, Ti / Pt 10/150 nm as upper electrode 111, protective film thereon 113 nm of SiO ₂ was deposited to 100 nm.

  In order to form a space behind the diaphragm 109 on the silicon substrate, a hole 107 serving as a diaphragm rear space and a hole serving as an ink supply port 108 from the back surface were formed by anisotropic etching.

  An individual pressure generating chamber 114 was formed on the substrate. The material of the pressure generating chamber was Ni and formed by plating. The height of the inner wall of the pressure generating chamber was 60 μm, and the wall thickness was 20 μm. A communication hole 115 was provided at the end of the pressure generation chamber and connected to a common liquid chamber (not shown).

  An ink discharge port 116 having a diameter of 26 μm is formed at the opposite end of the individual pressure generating chamber so that the ink pushed out by deformation of the vibration plate 109 is discharged through a path indicated by an arrow 117 and printed on the medium. .

  FIG. 2 is a top view of the substrate (electrodes and the like are not shown). Adjacent pressure generation chambers were arranged in parallel in a direction perpendicular to the Si (111) plane. In the figure, it is indicated by an individual pressure generating wall 114. The nozzles (discharge ports 116) are covered with the individual pressure generating walls 114, but the array pitch was 84.7 μm.

  FIG. 3 is a rear view. A pattern was formed so that the long sides of the parallelogram were parallel to the (111) plane of Si, and the diaphragm back space 107 and the ink supply port 108 were formed by wet etching using TMAH. The length of the diaphragm back space in the long side direction was 700 μm, and the length of the ink supply port in the long side direction was 500 μm.

  Using this head, a high-quality printed matter having 3 pl droplets at 30 KHz and a width of 12.5 mm and no non-ejection was obtained using an aqueous ink having a viscosity of 5 cp.

<Example 2>
A second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the diaphragm is formed below the piezoelectric element, whereas in the second embodiment, the diaphragm is formed on the piezoelectric element.

  The constituent elements are obtained by etching the Si diaphragm of Example 1, and a Pt electrode and YSZ are disposed under the piezoelectric element 208, and a 2 μm SiNx film deposited by plasma CVD is disposed on the piezoelectric element. It functions as the diaphragm 209.

  Using this head, an ink mainly composed of toluene having a viscosity of 3 cp was used, and a 3 pl droplet at 15 KHz, a width of 12.5 mm and a high-quality printed matter without ejection failure was obtained.

<Example 3>
An embodiment of the process of the ink jet recording head according to the present embodiment will be described step by step with reference to FIG.
(1) A silicon substrate 101 having an outer diameter of 150 mm, a thickness of 630 μm, and a substrate surface orientation of (110) is equivalent to (111) on each side as shown in FIG. 8 as viewed from above with a high-density plasma etching apparatus (ICP). A parallelogram-shaped recess (position corresponding to the diaphragm rear space 107 having a long side length of 3 mm and a short side length of 70 μm, which is parallel to the plane of ) And a parallelogram-shaped concave portion (position corresponding to the ink supply port 108) having a long side length of 500 μm and a short side length of 70 μm.
(2) On the surface of the silicon substrate 101 where the parallelogram recesses are formed, polysilicon is deposited by LPCVD and polished to form a sacrificial layer 102 in which the recesses are filled (FIG. 4 (1)). )reference).
(3) A 300 nm Si ₃ N ₄ film 103 was formed by LPCVD on the surface of the silicon substrate 101 where the parallelogram-shaped recesses were formed.
(4) Further, a SiO ₂ film 104 was deposited to a thickness of 100 nm on the silicon substrate 101 by a thermal CVD method (see FIG. 4B).
(5) A single crystal Si substrate having a plane orientation of (100) is bonded to the surface of the silicon substrate 101 where the parallelogram-shaped recesses are formed, and then polished to form a single crystal Si layer 105 ( (See FIG. 4 (3)). A YSZ film 106 having a thickness of 10 nm is formed as a buffer layer using a sputtering method in a Ar / O ₂ atmosphere at a substrate temperature of 800 ° C. (see FIG. 4D).
(6) In accordance with the sacrificial layer 102 forming the diaphragm back space 107, Pt having a thickness of 150 nm was deposited using a sputtering method under a substrate temperature of 800 ° C. in an Ar atmosphere to form the lower layer electrode 112.
(7) On the lower electrode 112, a PZT single crystal having a thickness of 2 μm was deposited using a reactive sputtering method at a substrate temperature of 600 ° C. in an Ar / O ₂ atmosphere to epitaxially grow the piezoelectric element film 110.
(8) Thereafter, Ti 10 nm and Pt 150 nm were deposited by sputtering as the upper electrode 111, and patterning was performed by etching using a photolithography method to form a piezoelectric element portion (see FIG. 4 (5)).
(9) A protective film 113 was formed by depositing a 100 nm SiO _x film on the formed piezoelectric element using a plasma CVD method (see FIG. 5A).
(10) The communication hole 115 connected to the ink supply port was formed by etching (see FIG. 5B).
(11) A photoresist (trade name PMER HM-3000PM, manufactured by Tokyo Ohka Kogyo Co., Ltd.) having a thickness of 60 μm is formed on a substrate to a thickness of 60 μm by using a spinner and patterned using a photolithography method (FIG. 5 (3)).
(12) Ti / Cu to be a conductive layer 119 to be a plating seed layer at the time of plating was formed and patterned to a thickness of 25 nm / 75 nm by sputtering. Ti was deposited for the purpose of improving the adhesion and conductivity of the Cu substrate.
(13) A photoresist (trade name PMER LA-900PM manufactured by Tokyo Ohka Kogyo Co., Ltd.) to be the discharge port mold material 120 was formed to 25 μm with a spinner, dried and then patterned. For the exposure of the mold material, a proximity type exposure machine was used, and the gap between the mask and the substrate was set to 120 μm to form a taper shape.
(14) Next, a Ni layer was formed to 18 μm by electroplating, and then a Ni—PTFE composite plating layer was formed to 3 μm by electroless plating to form a pressure chamber wall 114.
(15) Next, in order to protect the substrate surface side, OBC, which is a cyclized rubber resin manufactured by Tokyo Ohka Kogyo Co., was applied to the substrate surface to form an etching protective film 121 (see FIG. 6 (3)). Thereafter, a leading hole 129 was formed by laser processing in the vicinity of the narrow angle of the parallelogram on the back surface (see FIG. 7 (1)). The lead hole had a diameter of 20 μm and a depth of 80% of the thickness of the substrate. The substrate was subjected to anisotropic etching at TMAH 22 wt% and 80 ° C. for a predetermined time.

If the diameter of the leading hole is too narrow, it becomes difficult to open a deep hole of 80% (about 500 μm) of the substrate, and if the diameter is too wide, it takes too much time to form the deep opening. The diameter is preferably about 15-30 μm.
(16) After anisotropic etching, the etching protective film 121 was removed with xylene, and then the Si ₃ N ₄ layer 103 as an etching stop layer was removed by chemical dry etching (CDE method). Here, the diaphragm 109 was formed. Finally, the mold was removed using a direct path made by Arakawa Chemical Industries. At this time, the trade name Pine Alpha ST-380 manufactured by Arakawa Chemical Industries, Ltd. was used as the solvent.

  The completed head had a discharge port upper surface of 20 μm and a lower surface of 30 μm. The partition wall of the pressure generating chamber was 21 μm. The length of the formed free space in the long side direction was 3 mm, and the length of the ink supply port in the long side direction was 500 μm.

  Using this head, a high-quality printed matter having no ejection with 5 pl droplets at 25 KHz was obtained using aqueous ink having a viscosity of 2 cp.

<Example 4>
The manufacturing process of the ink jet recording head of this embodiment will be described in order with reference to FIGS.
(1) A silicon substrate 301 having an outer diameter of 150 mm and a thickness of 200 μm was thermally oxidized, and then the surface was etched to form a 600 nm SiO ₂ film 302 on the back surface.
(2) Thereafter, a Si ₃ N ₄ film 303 having a thickness of 300 nm was deposited on the surface of the silicon substrate 301 by LPCVD (see FIG. 10A).
(3) An epitaxially grown silicon layer of a single-crystal Si substrate obtained by epitaxially growing Si to 200 nm and Si of the silicon substrate 301 are formed by anodizing the surface of a single-crystal Si substrate having a substrate plane orientation (100). ₃ After bonding the N ₄ film 303 at a high temperature, the single crystal Si substrate is peeled off from the porous layer, and the surface is etched with an aqueous solution containing 0.3% hydrofluoric acid and 20% hydrogen peroxide. A single crystal Si layer 304 was formed by annealing at 1000 ° C. in H 2 (see FIG. 10B).
(4) A YSZ film having a thickness of 10 nm was formed as a buffer layer 305 on the single crystal Si layer 304 using a sputtering method at a substrate temperature of 800 ° C. and in an Ar / O 2 atmosphere (see FIG. 10 (3)).
(5) Pt having a thickness of 150 nm was formed as the lower layer electrode 306 using a sputtering method at a substrate temperature of 800 ° C. and in an Ar atmosphere.
(6) On the lower electrode 306, 2 μm of PZT single crystal was deposited at a substrate temperature of 600 ° C. in an Ar / O ₂ atmosphere by reactive sputtering, and the piezoelectric element film 307 was epitaxially grown.
(7) Ti: 10 nm and Pt: 150 nm were deposited by sputtering on the piezoelectric element film 307 as the upper electrode 308 and patterned (see FIG. 10 (4)).
(8) On the formed piezoelectric element portion, a protective film 309 was formed by depositing a 2 μm SiN _x film using a plasma CVD method (see FIG. 11A).
(9) The buffer layer 305, the single crystal silicon layer 304, and the Si ₃ N ₄ film 303 were removed by etching to form a communication hole 310 connected to the ink supply port.
(10) A photoresist (trade name PMER HM-3000PM, manufactured by Tokyo Ohka Kogyo Co., Ltd.) having a thickness of 60 μm was formed on the substrate with a spinner, and patterned after drying.
(11) Ti / Cu to be the conductive layer 312 at the time of plating was formed to a thickness of 25 nm / 75 nm by sputtering and then patterned. Ti was deposited for the purpose of improving the adhesion and conductivity of the Cu substrate.
(12) A photoresist (trade name PMER LA-900PM, manufactured by Tokyo Ohka Kogyo Co., Ltd.) to be a mold 313 for the discharge port was formed to a thickness of 25 μm with a spinner, and was patterned after drying. For the exposure of the mold material, a proximity type exposure machine was used, and the gap between the mask and the substrate was set to 120 μm to form a taper shape.
(13) Next, an Ni layer was formed to 18 μm by electroplating, and then a Ni—PTFE composite plating layer was formed to 3 μm by electroless plating to form a pressure chamber wall 314 (see FIG. 12 (2)).
(14) The SiO ₂ 302 on the back surface was patterned as shown in FIG. 12 (3) to form the opening 315 and the opening 316. Next, using these openings, Si was etched by ICP, and a depth of up to Si ₃ N ₄ was dug.
(15) The SiN layer 303 and the Si layer 304, which are etching stop layers, were removed by chemical dry etching (CDE method) (see FIG. 13B). The mold material 311 was removed using a direct path manufactured by Arakawa Chemical Industries. At this time, the trade name Pine Alpha ST-380 manufactured by Arakawa Chemical Industries, Ltd. was used as the solvent (see FIGS. 13 (3) and 14). A liquid discharge head was manufactured by removing the mold material of the discharge port and the plating seed layer there.

  The completed head had a discharge port upper surface of 26 μm and a lower surface of 33 μm. The partition wall of the pressure generating chamber was 21 μm. The length of the formed free space in the long side direction was 3 mm, and the length of the ink supply port in the long side direction was 500 μm.

  Using this head, a high-quality printed matter having no ejection with a 20 pl droplet at 15 KHz was obtained using a water-based ink having a viscosity of 2 cp.

1 is a cross-sectional view of an ink jet recording head according to the present invention. 1 is a top view of an ink jet recording head according to the present invention. 2 is a bottom view of an ink jet recording head according to the present invention. FIG. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. 1 is a cross-sectional view of an ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. FIG. 5 is a process cross-sectional view of the ink jet recording head according to the present invention. 2 is a bottom view of an ink jet recording head according to the present invention. FIG.

Claims (8)

A liquid having a pressure generating chamber communicating with a discharge port for discharging a liquid, and a piezoelectric element provided corresponding to the pressure generating chamber and including a piezoelectric material film and a pair of electrode films sandwiching the piezoelectric material film A method for manufacturing a discharge head, comprising:
Preparing a structure in which a single crystal Si layer is laminated on the surface of a Si substrate via an etching stop layer;
Forming a buffer layer on the single crystal Si layer;
Forming the piezoelectric material film formed of a single crystal thin film or a thin film preferentially oriented in a polarization direction on one of the pair of electrode films on the buffer layer;
Forming the pressure generating chamber on the piezoelectric material film;
Etching a portion corresponding to the piezoelectric material film of the Si substrate from the back side of the Si substrate until reaching the etching stop layer;
A method of manufacturing a liquid discharge head, comprising:   The method for manufacturing a liquid ejection head according to claim 1, wherein a sacrificial layer capable of being selectively etched is provided between the surface of the Si substrate and the etching stop layer.   The step of forming the pressure generating chamber includes a step of forming a pattern to be the pressure generating chamber on the diaphragm, a step of forming a member constituting the wall of the pressure generating chamber on the pattern, The method of manufacturing a liquid ejection head according to claim 1, further comprising: forming the pressure generating chamber by removing the pattern.   The method of manufacturing a liquid discharge head according to claim 1, wherein the surface orientation of the Si substrate is {110}.   The method of manufacturing a liquid discharge head according to claim 1, wherein the etching is crystal axis anisotropic etching.   The method of manufacturing a liquid ejection head according to claim 3, wherein the step of removing the pattern and forming the pressure generating chamber is performed after the etching step.   2. The liquid ejection head according to claim 1, further comprising: forming a liquid supply port communicating with the pressure generation chamber in the substrate by removing a part of the substrate and a part of the etching stop layer. Production method. A method for manufacturing a substrate for a liquid discharge head having a piezoelectric element including a piezoelectric material film and a pair of electrode films sandwiching the piezoelectric material film,
Preparing a structure in which a single crystal Si layer is laminated on the surface of a Si substrate via an etching stop layer;
Forming a buffer layer on the single crystal Si layer;
Forming the piezoelectric material film formed of a single crystal thin film or a thin film preferentially oriented in the polarization direction on one of the electrode films on the buffer layer;
Etching a portion corresponding to the piezoelectric material film of the Si substrate from the back side of the Si substrate until reaching the etching stop layer;
A method for manufacturing a substrate for a liquid discharge head, comprising:

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