JP2009067025A - Ink jet head and manufacturing method for ink jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin-film piezoelectric ink jet head that has a high performance actuator. <P>SOLUTION: A substrate and a passage formation member are integrated by a conductive layer. A portion for forming a liquid chamber by anodization is made porous. After a vibrating plate and an actuator are formed on this portion, a nozzle portion is cut, and the porous portion is etched. Thereby a head is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ink jet head configured by joining a plurality of flow path substrates and a method for manufacturing the same, and more particularly to an ink jet head using a thin film piezoelectric actuator suitable for industrial use and a method for manufacturing the same.

  Ink-jet heads for ejecting minute droplets are being developed not only for consumer use such as printers, but also for industrial uses such as wiring pattern direct drawing devices and liquid crystal color filter manufacturing. Various types of ink-jet heads have been put into practical use, but in industrial applications, development of types using piezoelectric elements is progressing due to the large tolerance for ink. For example, in Patent Document 1, a uniform piezoelectric thin film is formed by the film forming technique over the entire surface of the diaphragm, and this piezoelectric thin film is divided into shapes corresponding to the pressure generating chambers by lithography to generate each pressure. An actuator in which an actuator is formed so as to be independent for each chamber has been proposed. This eliminates the need for attaching the actuator to the diaphragm, and allows the actuator to be formed on the thin film diaphragm by a precise and simple technique called a lithography method. There is an advantage that the thickness can be reduced and high-speed driving becomes possible. In the above publication, there is a so-called edge shooter type in which a discharge port is formed so that droplets are discharged in a direction parallel to the substrate surface. A side shooter type ink jet head is generally configured by joining a flow path substrate having an actuator and a nozzle plate having fine discharge ports.

  There are two methods for bonding the flow path substrate and the nozzle plate: one using an adhesive and the other using a solid phase bonding using Au or the like. It has excellent characteristics as a method for joining ink jet heads, such as no inflow of ink.

However, in the side shooter type that requires these joining steps, there is a problem in that the discharge performance of each nozzle varies because the positional displacement between the liquid chamber and the orifice plate occurs during joining.
Japanese Patent Laid-Open No. 5-286131

  An object of the present invention is to provide a thin-film piezoelectric ink jet head in which the liquid chamber and the nozzle are not displaced. Still another object of the present invention is to provide a method of manufacturing a thin film piezoelectric ink jet head having a high performance actuator without an orifice plate bonding process. Another object of the present invention is to provide a method for manufacturing a thin film piezoelectric ink jet head that can reduce the high cost due to damage in the process or loss due to bonding even when a silicon substrate capable of high-precision processing is used. It is a thing.

  The present invention has been made in view of the above problems, and an ink jet head according to the present invention includes a substrate in which a flow path is formed on a silicon substrate, and the silicon substrate on which the flow path is formed and another member are provided. It is characterized by being integrated through a metal. The inkjet head manufacturing method of the present invention includes a substrate having a channel formed on a silicon substrate, and the silicon substrate on which the channel is formed and another member are integrated via a metal. In the method of manufacturing a head, a step of providing a metal film for anodization on a silicon substrate, a step of forming a silicon film on the metal film, and a portion serving as a flow path and a nozzle on the silicon film. A step of forming a silicon film as a vibration plate thereon, a step of creating an actuator on each vibration plate, a step of cutting a nozzle portion and forming a flow path by etching It is characterized by including.

  According to the ink jet head and the manufacturing method thereof of the present invention, it is possible to produce a thin film piezoelectric ink jet head having a thin film piezoelectric actuator that can produce an ink jet head without a bonding step and has little characteristic deterioration due to damage in the production process.

  As described above, according to the present invention, a thin film piezoelectric ink jet head having a high performance actuator can be obtained without a bonding step. Further, even if a silicon substrate is used, a thin film piezoelectric ink jet head that is less damaged during the process can be obtained.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  The present invention will be described below with reference to the drawings.

  FIG. 1a is a cross-sectional view of an inkjet head made according to the present invention.

  FIG. 1B is a process diagram showing an example of the inkjet head manufacturing method of the present invention.

  First, a flat substrate is prepared, and a conductor is formed on the surface (1). As the substrate, a silicon substrate that is relatively inexpensive and excellent in flatness, a heat-resistant material such as polished glass, a metal plate, and ceramics can be used. In this example, a 6-inch silicon wafer (with a thermal oxide film of 1 μm) having a thickness of 625 μm was used.

  As the conductor formed on the substrate, a metal, particularly a noble metal such as gold or platinum, or an oxide conductive film such as ITO is preferable. In this example, a 30 nm thick Ti film was formed on the adhesion layer, and a 100 nm thick platinum film was formed thereon as a conductive layer. On this, a predetermined thickness of silicon is deposited by CVD (2). Since this thickness determines the height of the liquid chamber, it is necessary for the film formation to be uniform, and the film thickness variation within the chip needs to be within 10%. In this example, the thickness was 25 μm. Generally, the height of the liquid chamber is preferably about 20 to 200 μm. A photoresist is applied to the silicon surface of the substrate thus obtained, and an ink flow path pattern is formed by mask exposure & development. (3)

The conductive material of this substrate was used as an electrode, and an ink flow path portion of the formed silicon was anodized to form a porous silicon layer. As a chemical conversion solution, a silicon substrate with a chemical conversion mask formed in an aqueous solution of 10% hydrofluoric acid and 8% isopropyl alcohol is installed, and platinum electrodes are placed opposite to each other so that the surface on which porous silicon is formed becomes the cathode. A current is applied between the electrodes at a current density of 80 mA / cm ² for 15 minutes. (Then, this porous silicon may be thermally oxidized.) Further, silicon is formed thereon by CVD film formation. (4) This is a portion that becomes a diaphragm, and a film thickness of about 2 to 10 μm is suitably used.

  Next, a thin film piezoelectric actuator was fabricated thereon. (5) FIG. 3 is a diagram for explaining the manufacturing process of the thin film piezoelectric actuator. For simplification, the portion below the thin film diaphragm 3 in FIG. 1 is omitted. As shown in FIG. 3A, titanium 30 nm and Pt 300 nm were sequentially formed on the insulating film 4 on the thin film diaphragm 3 by a sputtering method to form the lower electrode 5. Next, lead zirconate (PZT) was formed to a thickness of 3 μm by sputtering and heat-treated at 700 ° C. in an oxygen atmosphere to form a thin film piezoelectric body 6. Further, titanium 30 nm and Pt 300 nm were formed on the thin film piezoelectric body 6 by the sputtering method to form the upper electrode 7. After the upper electrode 7 is formed, an upper electrode etching mask 18 is formed as shown in FIG. The upper electrode 7 is formed by dry etching of Pt and titanium using the etching mask 18. (FIG. 3C) Next, the etching mask 18 is removed as shown in FIG. 3D, and an etching mask 19 for PZT is formed as shown in FIG. 3E. PZT is etched using this etching mask 19 (FIG. 3F). Finally, the etching mask 19 is removed to complete the thin film piezoelectric actuator 8 (FIG. 3G). This was put into an electric furnace, and PZT was fired at 700 ° C. for 5 hours.

  Next, individual chips were cut out from the wafer, the portion to be the nozzle was cut, and (6) the portion that became porous by anodization was wet etched to complete the liquid flow path. ((7)) Thereafter, the inside of the flow path was thoroughly washed, an ink supply pipe was attached, and an FPC was mounted to obtain an ink jet head.

  In this way, the thin film piezoelectric ink jet head manufactured in this example passed through 700 ° C of the thermal process of the thin film piezoelectric material, but since there was no subsequent thermal history, no deterioration was seen, and stable ejection characteristics was gotten.

  In addition, since there was no bonding process, 10 wafers were flowed to the prototype line. However, because a 6-inch silicon wafer with a thickness of 625 μm was used for the substrate, there was no damage, and there was no bonding process, so there was a problem due to nozzle misalignment. There wasn't.

(Comparative example)
On the other hand, FIG. 2 is a cross-sectional view of an inkjet head manufactured by a conventional method.

  The flow path substrate 15 in which the pressure generating chamber 9 is formed in the silicon substrate 2 and the nozzle plate 16 in which the ink discharge port 11 and the communication path 10 to the pressure generating chamber 9 are formed in the silicon substrate 1 are bonded by Au-Au bonding. The ink jet head is formed by bonding. The flow path substrate 15 includes a thin film diaphragm 3, an insulating film 4, a thin film piezoelectric actuator 8 including a common electrode 5, a piezoelectric thin film 6, and individual electrodes 7. Titanium thin films 13a and 13b are provided as an undercoat layer of Au and silicon between the Au—Au bonding layer 12, the silicon substrate 2 of the flow path substrate 15, and the silicon substrate of the nozzle plate.

  When this was converted into a head in the same manner as in the example, the characteristics of the actuator deteriorated by about 10%.

  Moreover, although 10 wafers were flowed to the trial production line, since an SOI wafer having a thickness of 200 μm was used for the substrate, three of them were broken during the processing.

  In addition, one of all the completed steps had a deviation of about 10 μm from the target position during bonding.

1 is a schematic diagram of an inkjet head according to the present invention. Schematic diagram showing an example of a conventional inkjet head. Manufacturing process drawing of a thin film piezoelectric actuator.

Explanation of symbols

1 Substrate
2 Silicon film
3 Thin film diaphragm (silicon film)
4 Insulating layer
5 Lower electrode
6 Thin film piezoelectric
7 Upper electrode
8 Thin film piezoelectric actuator
9 Pressure generation chamber
10 Underlayer
11 Metal layer
12 Communication part
13 nozzles
14 Underlayer
15 Bonding layer
16 Nozzle plate
18 Etching mask for upper electrode formation
19 Etching mask for forming thin film piezoelectric part

Claims (2)

  An ink jet head comprising: a substrate having a channel formed on a silicon substrate; and the silicon substrate on which the channel is formed and another member are integrated via a conductor.   In a method of manufacturing an inkjet head, which includes a substrate having a channel formed on a silicon substrate, and the silicon substrate on which the channel is formed and another member are integrated via a conductor, A step of providing a conductor film for anodization, a step of forming a silicon film on the conductor film, a step of forming a portion to be a flow path and a nozzle in the silicon film, and a step thereof An inkjet head comprising: a step of forming a silicon film to be a vibration plate; a step of creating an actuator on each vibration plate; and a step of cutting a portion to be a nozzle and forming a flow path by etching. Production method.

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