JP2007296818A - Manufacturing method of liquid discharge head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently produce a piezo-electric diaphragm of a piezo-electric driver for generating a discharge pressure in liquid at a high aspect. <P>SOLUTION: An oscillating board 10 is formed on the surface of a substrate 1 having a liquid chamber 2 which communicates to an outlet port for discharging the liquid, and then the films of a lower electrode 21, a piezo-electric diaphragm 22, and an upper electrode 23 are sequentially formed thereon. The piezo-electric diaphragm 22 is formed by an aerosol deposition method, in which fine particle is mixed in a transfer gas and sprayed from a nozzle without performing masking. Then, patterning of a predetermined shape is carried out on the upper electrode 23 and the piezo-electric diaphragm 22 using a masks or a resist. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid discharge head mounted on a liquid discharge apparatus such as an ink jet recording apparatus.

  In recent years, proposals for industrial applications of liquid ejection devices using inkjet or the like have become active. Since ink jet is direct drawing, it is a very advantageous technique compared to other device forming means in terms of material utilization efficiency and environmental load. Such an ink jet technology has a pressure generator composed of a laminate of a piezoelectric film such as PZT (lead zirconate titanate), a metal plate, and ceramics, and pressure applied to the pressure generator by the applied voltage is set as discharge energy. There is a method of ejecting ink (liquid) by generating the ink. Also known is an on-demand ink jet head composed of a heat generating element that obtains pressure by foaming a liquid by applying thermal energy to the ink.

  Among these liquid ejection methods, those equipped with a pressure generator using a piezoelectric film are those that use a bending mode called Kyzer type, direct pressing type called piston type, share mode that moves the side wall, etc. Various types of heads have been commercialized.

  The piezoelectric film is formed into a pattern on a metal plate or the like by a sputtering method or the like. In recent years, it has also been proposed to form a piezoelectric film using an arc-type gas deposition method or an aerosol-type gas deposition method.

  In the gas deposition method, as shown in FIGS. 4 and 5, ultrafine particles having a particle size of several nanometers to several tens of nanometers, or microparticles having several tens of nanometers to several μm are sprayed onto the substrate W through the nozzle 100 to form a film. Technology. As shown in FIG. 4, the deposition apparatus using the gas deposition method supplies an ultrafine particle generation chamber 101 that generates ultrafine particles in the case of an arc type, and supplies existing fine particles in the case of an aerosol type as shown in FIG. An aerosol generation chamber 111 is provided. Further, a film forming chamber 102, a transfer pipe 103, a transfer gas introduction path 104, and the like are provided. In the film formation, the fine particles supplied from the ultrafine particle generation chamber 101 or the aerosol generation chamber 111 are guided to the film formation chamber 102 by a differential pressure with respect to the film formation chamber 102 and sprayed from the nozzle 100 at a high speed, thereby directly patterning on the substrate W. Form. At this time, an arbitrary pattern can be drawn by scanning the substrate W.

  In the method of forming ultrafine particles in the ultrafine particle production chamber 101 of FIG. 4, the material 106 is heated and melted by using an arc 105 or a heating source such as resistance heating, high frequency induction heating, or laser for forming ultrafine particles. Then, the evaporated material is collided with an inert gas to generate ultrafine metal particles. Further, in the supply of fine particles by aerosol in FIG. 5, various gases such as an inert gas and air are introduced into the aerosol generation chamber 111 from the gas introduction path 107, and the fine particles are aerosolized and supplied by vibration and stirring.

  In particular, the gas deposition method using aerosol for supplying fine particles is called an aerosol deposition method, and has been actively researched in recent years.

  The aerosol deposition method has a high film formation speed, and a film formation speed several times or more can be obtained by film formation of, for example, PZT (lead zirconate titanate) or the like as compared with the sputtering method. In the sputtering method, it takes several hours to several tens of hours to form a thick film of several μm to several tens of μm, but in the aerosol deposition method, it can be formed in a relatively short time depending on the film forming region. It is.

  In addition, when PZT is formed as a thick film of several tens of μm by sputtering, there is a problem that the Pb component is lost during film formation and it is difficult to maintain a uniform composition, but in the aerosol deposition method, The composition of the material used is almost the same as the film composition as it is.

  In addition, as a method of forming a thick film of PZT, there is a method of mechanically thinning from a bulk and fixing with an adhesive. However, an oxide-based piezoelectric material represented by PZT is a brittle material, so it is thinned. There is a limit to processing, and it can only be done up to about 0.1 mm. In addition, there is a problem that the adhesive absorbs strain due to piezoelectricity, and the influence becomes particularly large in a high frequency band. Therefore, the aerosol deposition method has many advantages over other methods for forming a thick PZT film.

As a method of forming a film patterned by a gas deposition method, as disclosed in Patent Document 1, a method of forming a desired pattern film by providing a mask between a substrate and a nozzle is known. Patent Document 2 also discloses a method in which a portion other than the film forming portion of the substrate is covered with a resist in advance, and the resist is removed after forming the film to obtain a desired pattern film.
Japanese Patent No. 3015869 JP 2003-142750 A

  However, when patterning is performed by masking, as shown in FIGS. 6A and 6B, the edge portion 204a of the film 204 formed on the substrate 201 using the mask 202 or the resist pattern 203 is formed at the bottom. It becomes a shape that sags as if pulled.

  That is, the cross-sectional shape of the film 204 is such that the side wall is not perpendicular to the base body 201 and the film thickness decreases from the center to the outside. This is considered to be due to the influence of the edge portions and side wall portions of the mask 202 and the resist pattern 203.

  In addition, as shown in FIGS. 7A and 7B, when the film is formed so that the portion other than the film forming portion is covered with the resist 205 and the entire substrate is covered, the resist sidewall is removed when the resist 205 is peeled off. Depending on conditions such as the taper angle, a burr-like defect may occur on the side surface of the film 206.

  When the cross-sectional shape of the piezoelectric film formed by the aerosol deposition method is trapezoidal, or when defects such as burrs occur, the electric field strength distribution in the piezoelectric film is not uniform, so deformation due to piezoelectric driving Or the movement becomes uneven. In addition, the trapezoidal shape with a skirt as described above is disadvantageous even when the line interval is narrowed.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and provides a method of manufacturing a liquid discharge head including a piezoelectric driving unit having a piezoelectric film patterned with high accuracy. It is the purpose.

  In order to achieve the above object, a method of manufacturing a liquid discharge head according to the present invention includes a liquid chamber communicating with a liquid discharge port, and a piezoelectric film for applying energy used to discharge liquid from the discharge port. In a method of manufacturing a liquid discharge head, comprising: a first electrode and a second electrode provided so as to sandwich the piezoelectric film, and a piezoelectric driving unit provided corresponding to the liquid chamber. Forming the first electrode on a wall and forming a piezoelectric layer thereon by a gas deposition method; forming an electrode layer on the piezoelectric layer; and forming the electrode layer on the second electrode And a step of patterning the piezoelectric layer into a shape of the piezoelectric film.

  A piezoelectric layer is formed by an aerosol deposition method, and an electrode layer is formed thereon, and then patterned in a separate process with high accuracy into the shapes of the second electrode and the piezoelectric film of the piezoelectric drive unit. As a result, it is possible to form a high-aspect aspect of a piezoelectric film having a thickness of several μm to several tens of μm with no burr-like defects and no skirt.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  As shown in FIG. 1A, a vibration plate 10 constituting a wall of a liquid chamber 2 is formed on a substrate 1 of a liquid discharge head having discharge ports. A lower electrode (first electrode) 21 is formed thereon as shown in FIG. 1B, and a piezoelectric layer 22a is formed on the lower electrode 21 by an aerosol deposition method without masking. Further, after the electrode layer 23a is formed on the piezoelectric layer 22a, the electrode layer 23a is formed as shown in FIG. 2A using the resist pattern 31 formed as shown in FIG. The upper electrode (second electrode) 23 is formed by patterning. Next, as shown in FIGS. 2B and 2C, the piezoelectric film 22 is formed by patterning the piezoelectric layer 22 a using the resist pattern 32.

  The above patterning is performed by dry etching, wet etching, or a combination thereof.

  It is difficult to form a rectangular cross-section of the piezoelectric film in the film formation process using a film formation method in which a mask such as a metal is placed between the nozzle and the substrate as in the conventional example, or a film formation method using lift-off using a resist. It is. On the other hand, in the present embodiment, the upper electrode and the piezoelectric film are processed into a desired pattern in a separate process after the film formation, so that a pattern film having a rectangular film cross section can be formed. Further, no burr-like defect occurs on the film end face.

  For patterning the upper electrode and the piezoelectric film, it is effective to use dry etching such as plasma etching, RIE (Reactive Ion Etching), μ-wave plasma etching, or wet etching using various etching solutions. It is also effective to use a combination of these.

  As shown in FIG. 3, a quartz glass substrate is bonded as a vibration plate 10 to a Si substrate (substrate) 1 having a discharge port and a liquid chamber 2, and a lower electrode 21 and a piezoelectric film are formed thereon as follows. 22 and the piezoelectric drive part 20 which consists of the upper electrode 23 was formed.

  First, a vibration plate made of a quartz glass substrate was formed as a lower electrode by sputtering with Ti of 40 nm and Pt of 0.5 μm. Next, a PZT film (piezoelectric layer) was formed to a thickness of 5 μm by the aerosol deposition method.

  In this step, the material powder is put into the aerosolization chamber of the film forming apparatus shown in FIG. 5, and dry air is introduced while vibrating and agitating the powder in the container. The film was introduced into the film forming chamber by pressure and sprayed through a nozzle to form a film.

The conditions at the time of film formation are as follows.
・ Material used: Sakai Chemicals, trade name PZT-LQ (average primary particle size 0.1 to 0.5 μm)
・ Ultrafine particle generation chamber pressure: 70KPa
-Film formation chamber pressure: 1 KPa
-Gas used: Dry air-Gas flow rate: 4 L / min.
・ Nozzle: slit type nozzle with 300 μm × 5 mm opening ・ Substrate temperature: 400 ° C.
・ Nozzle temperature: 400 ℃

  Next, after PZT film formation, baking was performed at 600 ° C. for 1 hour in an air atmosphere.

  Thereafter, Ti was deposited with a thickness of 40 nm and Pt with a thickness of 160 nm as an electrode layer serving as an upper electrode. At this time, a mechanical mask was used so that the upper and lower electrodes would not short-circuit at the film edge.

  After applying a positive resist for etching the upper electrode to form a resist pattern in a liquid chamber shape, Pt and Ti exposed by RIE (Reactive Ion Etching) were etched. Next, the resist for the upper electrode was removed, and the resist for PZT was patterned so as to surround the upper electrode. In this state, the PZT film was etched with hydrofluoric acid, then the resist was peeled off, IPA vapor cleaning was performed, and finally the substrate was cut for each head.

  In this way, a PZT film having a width of 100 μm, a length of 5 mm, and a thickness of 5 μm was formed, and when the side wall portion was confirmed with an electron microscope, the shape was almost perpendicular to the substrate, and a shape with a sag and a dip was seen There wasn't.

  A quartz glass substrate as a vibration plate was bonded to a Si substrate having a discharge port and a liquid chamber, and a high aspect piezoelectric film was formed thereon.

  First, a Ti 40 nm and Pt 0.5 μm film was formed as a lower electrode on a quartz glass diaphragm. Next, a PZT film having a thickness of about 50 μm was formed over the entire surface by the aerosol deposition method. In the same manner as in Example 1, the film formation method is the same as in Example 1. The PZT material is charged into the aerosolization chamber, the powder in the container is aerosolized by the vibration of the container and agitation by gas introduction, and the particles floating on the top are formed by the differential pressure. And sprayed through a nozzle to form a film.

  The deposition conditions of the PZT film by the aerosol deposition method are the same as in Example 1, but the film thickness was adjusted by the deposition time. After PZT film formation, baking was performed at 600 ° C. for 1 hour in an air atmosphere. Thereafter, Ti 40 nm and Pt 160 nm were formed by sputtering as the upper electrode. At this time, a mechanical mask was used so that the upper and lower electrodes would not short-circuit at the film edge.

  A positive resist was applied to etch the upper electrode to form a resist pattern having a liquid chamber shape, and then Pt and Ti exposed by RIE (Reactive Ion Etching) were etched. Next, the resist for the upper electrode was removed, and the resist for PZT was patterned so as to surround the upper electrode. The width of the resist patterned here was 50 μm. In this state, PZT was etched with hydrofluoric acid, and then the resist was peeled off, IPA vapor cleaning was performed, and finally the substrate was cut for each head.

  In this way, a high aspect PZT film having a width of 50 μm, a length of 5 mm, and a thickness of 50 μm was formed, and when the side wall portion of the shape was confirmed with an electron microscope, the shape was almost perpendicular to the substrate. The shape was not seen.

FIG. 10 is a process diagram illustrating the first half of the method for manufacturing a liquid ejection head according to one embodiment. FIG. 10 is a process diagram illustrating a latter half of the method for manufacturing the liquid ejection head according to the embodiment. It is a schematic cross section which shows the liquid discharge head by the said embodiment. It is a schematic diagram which shows an arc type gas deposition apparatus. It is a schematic diagram which shows an aerosol-type gas deposition apparatus. It is a figure explaining a prior art example. It is a figure explaining another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Liquid chamber 10 Diaphragm 20 Piezoelectric drive part 21 Lower electrode 22 Piezoelectric film 23 Upper electrode

Claims (3)

A liquid chamber communicating with a liquid discharge port, a piezoelectric film for applying energy used to discharge liquid from the discharge port, and a first electrode and a second electrode provided so as to sandwich the piezoelectric film, And a piezoelectric driving unit provided corresponding to the liquid chamber, and a method of manufacturing a liquid discharge head,
Forming the first electrode on the wall of the liquid chamber and forming a piezoelectric layer thereon by a gas deposition method;
Forming an electrode layer on the piezoelectric layer;
Patterning the electrode layer into the shape of the second electrode;
Patterning the piezoelectric layer into the shape of the piezoelectric film;
A method of manufacturing a liquid discharge head, comprising:   The method of manufacturing a liquid ejection head according to claim 1, wherein the patterning of the electrode layer and the piezoelectric layer is performed by etching.   A liquid discharge head manufactured by the method for manufacturing a liquid discharge head according to claim 1.

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