JP3697255B2 - Method for manufacturing inkjet head valve - Google Patents

Description

  The present invention relates to a method for manufacturing an inkjet head valve and an inkjet head valve manufactured by the method.

  By applying energy such as heat to the ink, the ink undergoes a change in state accompanied by a steep volume change (bubble generation), and the ink is discharged from the discharge port by the action force based on this change in state, and this is recorded 2. Description of the Related Art An ink jet recording method for forming an image by adhering to a medium, a so-called bubble jet recording method is conventionally known. In a recording apparatus using this bubble jet recording method, as disclosed in Patent Document 1 and the like, an ejection port for ejecting ink, an ink channel communicating with the ejection port, and an ink channel An electrothermal converter as an energy generating means for discharging the arranged ink is generally arranged.

  According to such a recording method, a high-quality image can be recorded at high speed and with low noise, and the ejection ports for ejecting ink can be arranged with high density in the head that performs this recording method. Therefore, it has many excellent points that a high-resolution recorded image and a color image can be easily obtained with a small apparatus. For this reason, in recent years, this bubble jet recording method has been used in many office devices such as printers, copiers, and facsimiles, and has also been used in industrial systems such as textile printing apparatuses. .

  As the bubble jet technology is used in various products in this way, the following various demands have been increasing in recent years.

  For example, as a study on the demand for improvement in energy efficiency, optimization of a heating element such as adjusting the thickness of a protective film is cited. This method is effective in improving the propagation efficiency of the generated heat to the liquid.

  In addition, in order to obtain a high-quality image, a drive condition for providing a liquid discharge method capable of performing a good ink discharge based on the generation of a stable bubble with a high ink discharge speed is proposed. From the viewpoint, there has also been proposed an improved flow channel shape in order to obtain a liquid discharge head having a high filling (refill) speed of discharged liquid into the liquid flow channel.

  Of these channel shapes, the channel structure and the head manufacturing method described in Japanese Patent Laid-Open No. 2004-228, etc. have a back wave generated with the generation of bubbles (pressure toward the direction opposite to the direction toward the discharge port, That is, the invention focuses on the pressure toward the liquid chamber. This back wave is known as loss energy because it is not energy in the ejection direction.

  The head disclosed in Patent Document 2 has a valve for an ink-jet head that is located farther from the bubble foaming region formed by the heat generating element and located on the opposite side of the discharge port with respect to the heat generating element. The valve has an initial position as if attached to the ceiling of the flow path by a manufacturing method using a plate material or the like, and hangs down in the flow path as bubbles are generated. The present invention is disclosed as controlling energy loss by controlling a part of the above-described back wave with a valve.

  FIG. 4 shows a partially cutaway perspective view of an example of a liquid discharge head provided with the above-described ink jet head valve.

  In the liquid discharge head shown in FIG. 4, a heating element 2 that causes thermal energy to act on the liquid is provided on the element substrate 1 as a discharge energy generating element for discharging the liquid, and the heating element 2 is provided on the element substrate 1. The liquid flow path 7 is arranged corresponding to the above. The liquid flow path 7 communicates with the discharge port 5 and also communicates with a common liquid chamber 13 for supplying liquid to the plurality of liquid flow paths 7, and an amount of liquid commensurate with the liquid discharged from the discharge ports. Is received from the common liquid chamber 13.

  On the element substrate 1 of the liquid flow path 7, a 1 μm-thick plate having a flat surface portion, which is made of an elastic material such as a thin film resin or metal, faces the heating element 2 described above. An ink jet head valve is provided in which a movable member 6 is provided in a cantilever shape.

  In FIG. 4, when the heating element 2 is heated, heat acts on the liquid in the bubble generation region between the movable member 6 and the heating element, thereby generating bubbles based on the film boiling phenomenon. The pressure based on the generation of bubbles and the bubbles act on the movable member 6 and are displaced so as to open largely toward the discharge side around the fulcrum 6a as shown in FIG. It can lead to the arranged downstream side.

In order to manufacture the ink jet head valve as described above, conventionally, a valve material formed by an electroforming method or the like is used and bonded to a substrate.
U.S. Pat. No. 4,723,129 JP 63-199972 A

  When this valve material is bonded onto the substrate, it is necessary to provide a gap of about 1 to 20 μm between the movable member and the heating element in order to bring out the effect of the movable member sufficiently. In order to attach the valve formed by electroforming or the like so that there is a gap in the movable part, it is necessary to previously form a pedestal part on the substrate so that the valve can be fixed to the substrate. Moreover, in order to form a pedestal portion of, for example, 5 μm as high as the gap, and to prevent the pedestal portion from corroding the ink, it is necessary to form it by a method such as Au plating. In order to form the Au plating, Au sputtering or photolithography (hereinafter abbreviated as “photolitho”) patterning is required. Further, after forming the Au plating, it is necessary to place an electroformed valve on the surface of the Au pedestal, align the position, and fix it by a method such as a stud bump method, and it is difficult to align the valve with high accuracy.

  Therefore, it is difficult not only to control the thickness of the valve and to position the valve with high accuracy, but also to make the manufacturing process extremely complicated.

  An object of the present invention is to provide a novel method for manufacturing an ink jet head valve that solves the above-described problems, and an ink jet head valve manufactured by the method.

  The above object is achieved by the following means.

That is, the present invention includes a discharge port for discharging ink, an ink flow path communicating with the discharge port, and electrothermal transducers as energy generating means for ejecting ink to the ink flow path, In the method of manufacturing an ink jet head valve arranged in the ink flow path facing the electrothermal transducer of the ink jet head, the structure of the ink jet head valve has different stresses in tension and compression. An inkjet head having a structure in which a metal having a laminated structure is formed, and a step of forming a metal layer having a compressive stress by a sputtering method and a step of forming a metal layer having a tensile stress by a metal CVD method A valve manufacturing method is proposed, and the inkjet head valve is replaced with Ta, W, Pt, Mo, Cr, Mn, F Involves produced using Co, Ni, and Cu.

According to the present invention, it is possible to position the valve with high accuracy using a photolithography process and to easily control the thickness of the valve, thereby simplifying the process. In addition, according to the present invention, since the manufactured valve has a warped structure in advance, the power for deforming the valve at the time of foaming is not necessary, and it can be moved only at the time of refilling, so that the energy loss can be reduced.

  Hereinafter, the present invention will be specifically described by way of examples.

(Reference Example 1)
Figures 1-a-e and 2-f-j show the process flow for achieving the structure of the present invention.

First, in order to form a valve pedestal on a substrate, a PSG film having a thickness of about 5 μm is formed on Ta as a cavitation resistant film by a plasma CVD method at 350 ° C. (FIG. 1A). Next, in order to perform patterning by a photolithographic method, a resist is spin-coated and exposure development is performed. Here, PSG is used for forming the valve pedestal. However, the present invention is not limited to this, and other materials, for example, an inorganic material such as BPSG or SiO, or an organic material may be used as long as it does not change in the metal CVD process described later. Next, PSG is formed in a predetermined pattern by etching with buffered hydrofluoric acid (FIG. 1-b). Next, tungsten is formed to a thickness of about 5 μm on the substrate by selective tungsten (W) CVD under the conditions of WF ₆ / SiH ₄ / H ₂ = 10/7/1000 sccm, pressure 26.6 Pa, 260 ° C. This tungsten is selectively deposited only on the portion where Ta is exposed, and serves as a valve seat (FIG. 1-c). In this embodiment, W is selected as the valve pedestal. Regardless of this, any material having a function as a valve pedestal or a valve material may be used. Ta, Pt, Mo, Cr, Mn, Fe, Other films such as Co, Ni, and Cu may be used. Or the material of a base and a valve can be changed according to a function.

  Subsequently, on this, a wiring layer for metal CVD as a valve material is formed to a thickness of 1000 angstrom by sputtering using Pd as a material (FIG. 1-d). Here, the wiring is Pd, but other metal may be used. Next, a PSG film is formed to a thickness of about 5 μm at 350 ° C. by plasma CVD (FIG. 1-e). Although the PSG film is used here, the present invention is not limited to this, and other materials, for example, an inorganic material such as BPSG or SiO, or an organic material may be used as long as they do not change in the metal CVD process described later. Next, PSG is formed in a predetermined pattern by etching with buffered hydrofluoric acid (FIG. 2-f).

Next, tungsten is formed to a thickness of about 5 μm on this substrate under the conditions of WF ₆ / SiH ₄ / H ₂ = 10/7/1000 sccm, pressure 26.6 Pa, 260 ° C. by selective tungsten (W) CVD. This tungsten is selectively deposited only on the exposed portion of Pd to form a valve (FIG. 2-g).

Next, PSG around the valve is removed by buffered hydrofluoric acid (FIG. 2-h). Next, Pd as a wiring layer is removed with hydrogen peroxide (FIG. 2-i). Finally, PSG is removed by buffered hydrofluoric acid to form a pedestal and a valve (FIG. 2-j).
(Example 1)
In the steps shown in FIGS. 1A to 2J in Reference Example 1, if the underlayer wiring layer and the stress of metal CVD are prepared, the final form is not the sectional structure as shown in FIG. It can be set as the shape which the valve as shown in FIG. For example, if the underlayer wiring layer is formed with a compressive stress of 1 × 10 ⁹ dyn / cm ² and the metal CVD side is formed with a tensile stress of 1 × 10 ⁹ dyn / cm ² , the valve As shown in FIG. 5, it is deformed by warping to the metal CVD side. Since the valve formed in this way does not require power for deforming the valve at the time of foaming and moves only at the time of refilling, energy loss can be reduced.
(Usage example 1)
FIG. 3 is a cross-sectional view along the liquid flow path direction for explaining the basic structure of the liquid discharge head of the present invention.

  As shown in FIG. 3, this liquid discharge head includes an element substrate 1 provided with a plurality of heating elements 2 (only one is shown in FIG. 3) for providing thermal energy for generating bubbles in the liquid. The top plate 3 joined to the element substrate 1 and the orifice plate 4 joined to the element substrate 1 and the front end face of the top plate 3 are provided.

  The element substrate 1 is formed by forming a silicon oxide film or a silicon nitride film for insulation and heat storage on a substrate such as silicon, and patterning an electric resistance layer and wiring constituting the heating element 2 thereon. is there. The heating element 2 generates heat by applying a voltage from the wiring to the electric resistance layer and causing a current to flow through the electric resistance layer.

  The top plate 3 is for constituting a plurality of liquid flow paths 7 corresponding to the respective heat generating elements 2 and a common liquid chamber 8 for supplying liquid to the respective liquid flow paths 7. A channel side wall 9 extending between the two is integrally provided. The top plate 3 is made of a silicon-based material, and the pattern of the liquid flow path 7 and the common liquid chamber 8 is formed by etching, or silicon nitride, silicon oxide, or the like is formed on the silicon substrate by a known film formation method such as CVD. After depositing the material to be the channel side wall 9, the liquid channel 7 can be formed by etching.

  In the orifice plate 4, a plurality of discharge ports 5 corresponding to the respective liquid flow paths 7 and communicating with the common liquid chamber 8 through the respective liquid flow paths 7 are formed. The orifice plate 4 is also made of a silicon-based material. For example, the orifice plate 4 is formed by cutting a silicon substrate on which the discharge ports 5 are formed to a thickness of about 10 to 150 μm. The orifice plate 4 is not necessarily required for the present invention. Instead of providing the orifice plate 4, the thickness of the orifice plate 4 is formed on the top surface of the top plate 3 when the liquid flow path 7 is formed on the top plate 3. By leaving a considerable wall and forming the discharge port 5 in this portion, a top plate with a discharge port can be obtained.

  Further, in this liquid discharge head, the heating element 2 is divided so that the liquid path 7 is divided into a first liquid path 7 a communicating with the discharge port 5 and a second liquid path 7 b having the heating element 2. A cantilever-like movable member 6 is provided so as to face the surface.

  The movable member 6 has a fulcrum 6a on the upstream side of a large flow flowing from the common liquid chamber 8 to the discharge port 5 side through the movable member 6 by the liquid discharge operation, and a free end 6b on the downstream side of the fulcrum 6a. The heating element 2 is disposed at a position facing the heating element 2 at a predetermined distance from the heating element 2 so as to cover the heating element 2. A bubble generation region 10 is formed between the heating element 2 and the movable member 6.

  Based on the above configuration, when the heating element 2 is heated, heat acts on the liquid in the bubble generation region 10 between the movable member 6 and the heating element 2, thereby causing bubbles on the heating element 2 based on the film boiling phenomenon. Generate and grow. The pressure accompanying the growth of the bubbles preferentially acts on the movable member 6, and the movable member 6 is displaced so as to open largely toward the discharge port 5 with the fulcrum 6a as the center, as shown by the broken line in FIG. Depending on the displacement or the displaced state of the movable member 6, the propagation of pressure based on the generation of bubbles and the growth of the bubbles themselves are guided to the discharge port 5, and the liquid is discharged from the discharge port 5.

  That is, on the bubble generation region 10, the movable member 6 having the fulcrum 6a on the upstream side (common liquid chamber 8 side) of the liquid flow in the liquid flow path 7 and the free end 6b on the downstream side (discharge port 5 side). By providing the bubble, the pressure propagation direction of the bubble is guided to the downstream side, and the pressure of the bubble directly and efficiently contributes to the discharge. The bubble growth direction itself is guided in the downstream direction in the same manner as the pressure propagation direction, and grows larger downstream than upstream. Thus, by controlling the bubble growth direction itself with the movable member and controlling the bubble pressure propagation direction, the fundamental discharge characteristics such as discharge efficiency, discharge force, or discharge speed can be improved.

  On the other hand, when the bubble enters the defoaming step, the bubble rapidly disappears due to a synergistic effect with the elastic force of the movable member 6, and the movable member 6 finally returns to the initial position shown by the solid line in FIG. . At this time, in order to supplement the contraction volume of the bubbles in the bubble generation region 10 and to supplement the volume of the discharged liquid, the liquid flows from the upstream side, that is, the common liquid chamber 8 side, and enters the liquid flow path 7. Liquid filling (refilling) is performed, and this liquid refilling is efficiently and reasonably and stably performed along with the return action of the movable member 6.

According to the present invention, highly accurate valve positioning using a photolithographic process becomes possible, control of the valve thickness becomes extremely easy, and the process can be simplified by forming the valve in a film forming process. It can be done.

  It is also possible to make the valve warped by stress control of the undercoating metal and stress control of the CVD.

1A to 1E are cross-sectional views showing the first half of the manufacturing process of the inkjet head valve. 2F to 2J are cross-sectional views illustrating the latter half of the manufacturing process of the inkjet head valve. It is sectional drawing along the liquid flow path direction for demonstrating the basic structure of the liquid discharge head of this invention. It is a partially broken perspective view of an example of the liquid discharge head provided with the valve for inkjet heads. 1 is a cross-sectional view of an ink jet head valve manufactured in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Element substrate 2 Heat generating body 3 Top plate 4 Orifice plate 5 Ejection port 6 Movable member 6a Support point 6b Free end 7 Liquid flow path 7a First liquid flow path 7b Second liquid flow path 8, 13 Common liquid chamber 9 Flow path Side wall 10 Bubble generation region 34 Support member

Claims (2)

A discharge port for discharging ink, ink jet ink flow path communicating with the discharge port, formed by arranging an electro-thermal converting member as energy generating means for ejecting ink to the ink flow path In the method of manufacturing a valve for an ink jet head, which is disposed in the ink flow path facing the electrothermal transducer of the head ,
The structure of the valve for the inkjet head is a structure in which metals having different stresses in tension and compression are laminated, and
Forming a metal layer having a compressive stress by a sputtering method; and
Forming a metal layer with tensile stress by metal CVD
A method for manufacturing a valve for an ink jet head, comprising:   The manufacturing method of the valve for inkjet heads of Claim 1 which manufactures the said valve for inkjet heads using Ta, W, Pt, Mo, Cr, Mn, Fe, Co, Ni, Cu.

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