JP2007237601A - Inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the distortion and cracking of a substrate 1 and the deformation of an orifice plate, when an ink supply port is lengthened. <P>SOLUTION: A both sides-fixed beam structure 11 is formed on both or either of the front and back sides of the substrate in a part, serving as the ink supply port 10, by using a member which is not etched with an etching liquid for anisotropic etching. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming an ink jet recording head in which liquid is ejected from an orifice to form droplets.

  With respect to this type of ink jet recording head, for example, the ink jet recording method described in Japanese Patent Application Laid-Open No. Sho 54-51837 is another ink jet recording method in that thermal energy is applied to a liquid to obtain a driving force for droplet discharge. It has different characteristics.

  That is, in the recording method disclosed in the above-mentioned publication, the liquid that has been subjected to the action of thermal energy is superheated to generate bubbles, and droplets are discharged from the orifice at the tip of the recording head by the action force based on the generation of bubbles. It is characterized in that information is recorded by forming the droplets on the recording member.

  A recording head applied to this recording method generally includes an orifice provided for ejecting a liquid, and a heat acting portion that is a portion where heat energy for ejecting droplets communicated with the orifice acts on the liquid. A liquid discharge section having a liquid flow path having a liquid crystal structure as a part, a heating resistance layer as a heat conversion body that is a means for generating thermal energy, an upper protective layer that protects it from ink, and a lower layer for storing heat It has. By the way, as a method for forming high-density and high-precision nozzles and discharge ports, methods disclosed in Japanese Patent Laid-Open Nos. 5-330066 and 6-286149 have been proposed.

Japanese Patent Laid-Open No. 10-146979 proposes providing a rib structure on the orifice plate above the ink supply port in the nozzle manufacturing method.
JP 54-51837 A JP-A-5-330066 JP-A-6-286149 Japanese Patent Laid-Open No. 10-146979

In the manufacturing method of JP-A-6-286149, it has been proposed to increase the width that can be printed at one time in order to increase the printing speed. In order to increase the width that can be printed at one time, it is necessary to arrange the ink ejection ports long. If the ejection ports are arranged long, it is necessary to lengthen the ink supply port. Opening the ink supply port for a long time has the following problems. Substrate distortion due to opening the ink supply port for a long time In order to reduce the size of the substrate, particularly in terms of cost, it is necessary to reduce the size perpendicular to the printed width of the substrate. Since the ink supply port is formed in the vertical direction, if the ink supply port is processed on the substrate, the substrate itself is distorted, and the flatness of the discharge port cannot be maintained as shown in FIG.

2. Occurrence of substrate cracking during chip handling After forming together with a wafer or the like, it is divided into discharge elements and flows to the flow path member in a sticking process, but when divided into discharge elements, it becomes an elongated substrate. If a slit-like ink supply port is formed at the center of the elongated substrate, stress may be applied to the substrate when the substrate is gripped, and the substrate may be broken.

In particular, when the printing width is large, the length of the ejection element becomes long and the ink supply port becomes long, so that the stress is increased. Cracks due to deformation of the substrate at the time of joining the flow path member and cracks and deformation of the orifice plate due to the deformation of the substrate As the adhesive that joins the discharge element to the flow path member is required to have ink resistance, a thermosetting adhesive is used. It has been adopted. In addition, a resin is adopted for the flow path member because of its ease of processing and low cost. When the discharge element is bonded to the flow path member, it is bonded using a thermosetting adhesive. Therefore, when the discharge element and the flow path member return to normal temperature due to the difference in coefficient of thermal expansion, residual stress is generated in the discharge element. To do. Then, the substrate on which the ejection elements are formed is broken or the substrate is deformed, and the orifice plate formed thereon is deformed, the ejection direction is bent, and printing may be poor.

  Japanese Patent Laid-Open No. 10-146979 proposes a structure in which ribs are set up to prevent the deformation of the orifice plate. This is to prevent the deformation of the orifice plate when the orifice plate swells. Deformation cannot be suppressed from the size.

  Further, a method of forming a beam as shown in FIG. 9 at the ink supply port of the substrate is conceivable.

  The process of forming the ink supply port first by the manufacturing method described in JP-A-6-286149 and then applying the mold material for forming the nozzle is performed by laminating the mold material for forming the nozzle in the application process, or by laminating a dry film or a mold material at the time of lamination There are many restrictions such as deformation.

  Therefore, a method is adopted in which the ink supply port is formed by anisotropic etching after the step of applying the mold material for forming the nozzle and applying the nozzle material. When the ink supply port is formed by anisotropic etching, a {100} substrate is generally used as the silicon substrate. However, forming a beam using a {100} substrate has the following problems.

  First, in order to provide a beam on the substrate surface, if a mask having a beam shape is used on the back surface, even if the beam width is 50 μ, if the thickness of the substrate is 625 μ, the surface is 950 μ. When the beam width is 950 μm, nozzles of 400 μm or more are generated from the ejection port to the ink supply port, the nozzle refill is slowed down, and the frequency characteristics are greatly deteriorated. If the substrate is made thin, the process flow becomes difficult due to problems such as strength.

  Next, it is difficult to provide a beam on the back surface of the substrate using a back surface mask.

  As described above, it is difficult to provide a beam at the ink supply port on both the front surface and the back surface.

  The present invention has been made in view of the above problems, and even when the ink supply port is lengthened, the substrate is hardly distorted or cracked, the orifice plate is hardly deformed, and the print width can be increased. Because the distance from the ink supply port to the ink discharge port can be kept short and does not affect the ink refill, it is possible to create an inkjet recording head that has good frequency characteristics and can print at high speed. It is the purpose.

  In the present invention for achieving the above object, an ink jet recording head is provided with an ink flow path and an ink discharge port provided on a substrate provided with a heating resistor, and discharges ink by utilizing ink firing by heat generation of the heating resistor. A step of applying and patterning a resin of a mold material for forming a nozzle channel on a substrate provided with a heating resistor, a step of applying and patterning a resin forming an ink channel and an ink discharge port, and an ink supply port In an ink jet recording head having at least a step of etching a substrate for forming and a step of removing the mold material, the etching is performed on either or both of the front and back sides of the silicon substrate of the portion serving as the ink supply port. Have a double beam structure formed by a member that is not etched by the etching solution More was achieved.

  In the present invention, by providing the double beam structure as a reinforcing member on the surface of the silicon substrate, it is possible to suppress the distortion of the substrate when the ink supply port is lengthened.

  In addition, by forming the both beam structures on the substrate in advance by a member that is not etched by the anisotropic etching solution of silicon, etching is performed in the same manner as in the prior art to remove silicon in the portion serving as the ink supply port. Thus, it is possible to automatically form the ink supply port reinforced by the double beam structure.

  For these both beam structures, silicon containing a high concentration of p-type impurities such as boron can be used. In silicon containing a high concentration of p-type impurities, the holes contained in the high concentration function to hinder the progress of the etching reaction, so that the anisotropic etching speed becomes extremely slow and is not actually etched. . Therefore, it is possible to perform etching while leaving a high concentration p-type silicon layer portion.

  Further, in the present invention, the double beam structure is arranged at a position that does not hinder the flow of ink from the ink supply port to the ejection port, thereby making it possible to achieve a structure that does not affect the ink refill. As a result, high-frequency driving is possible, and an ink jet recording head capable of further high-speed printing can be realized.

  As described above, according to the present invention, even when the ink supply port is lengthened, the substrate is hardly distorted or cracked, the orifice plate is hardly deformed, and the print width can be made longer than before, and Since the beam can be formed in a desired shape and does not affect the ink refill, it is possible to produce an ink jet recording head having good frequency characteristics and capable of printing at high speed.

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

  The present embodiment shown in FIG. 2 is an example in which a double beam structure is provided only on the front side of the ink supply port.

  FIG. 1 shows a cross-sectional view taken along the line AA ′ of FIG.

  The present embodiment shown in FIG. 3 is an example in which a large number of beams are combined in a range that does not hinder the flow of ink from the ink supply port to the ink discharge port. As indicated by arrows in FIG. 3, a large number of beams are combined, but a path through which ink flows from the ink supply port to the ink flow path is secured.

  The present embodiment shown in FIG. 4 is an example in which beams are provided not only on the front side but also on the back side of the ink supply port. FIG. 4 shows an example in which the front and back beams are arranged at different positions.

  The method for producing the ink jet print head of the present embodiment as described above is as follows.

First, a silicon nitride film is formed and patterned on the surface of the silicon wafer 1 (crystal orientation <100>, thickness 600 μm) to form a desired both-beam mask. (FIG. 6B) Using this silicon nitride film as a mask, a boron buried layer having a desired thickness is formed by ion implantation, heat treatment, or the like. At this time, the boron concentration is preferably about 10 ²⁰ / cm ³ or more. After removing the nitride film of the mask, a silicon nitride film was formed as an etching stop layer 2 on the silicon wafer surface. Next, a silicon oxide film was formed as a mask member 8 for anisotropic etching on the back surface of the silicon wafer. (FIG. 6 (e)) Next, as the ink discharge pressure generating element 4, an electrothermal conversion element and a drive circuit for operating these elements were formed. (Fig. 6 (f))
Next, as a mold material 9 for forming an ink flow path, a dissolvable resin is applied and patterned (FIG. 6G), and a resin layer 6 serving as an ink flow path member is formed thereon. (FIG. 6 (h)) Next, the ink discharge port 5 is formed. (FIG. 6i) In this example, a photosensitive resin was used for the ink flow path member 6, and it was formed using photolithography.

  Next, the wafer was immersed in an aqueous solution of TMAH (tetramethylammonium hydroxide) at 80 ° C. for 16 hours to carry out crystal anisotropic etching of silicon. (FIG. 6 (j)) At this time, a rubber resist was applied as a protective film on the surface of the wafer on which the ink discharge ports 5 were formed, so that the TMAH aqueous solution was not in contact. The anisotropic etching stops at the silicon nitride film on the surface of the silicon wafer. At this time, since the previously formed boron buried layer is not etched, the double beam structure is completed.

  After the anisotropic etching is completed, the silicon oxide film used as a mask is immersed and removed in a hydrofluoric acid aqueous solution, and the silicon nitride film on the ink supply port 7 is removed by plasma etching using CF4. (Fig. 6 (k)) After removing the rubber resist on the wafer surface, finally removing the dissolvable resin 6 used as the mold material (Fig. 6 (l)), then cutting the chip into an ink supply member An ink jet head can be produced by bonding and electrical mounting.

  Here, the manufacturing method in the case where both the beam structures are arranged only on the front side is shown. However, if it is desired to arrange them on the back side, a boron buried layer may be formed on the back side as well. In this case, as shown in FIG. 5, at the start of etching, the boron buried layer functions as a mask and the shape of anisotropic etching changes, but as the etching proceeds, the upper part of the beam is also etched by side etching, Eventually, substantially the same ink supply port shape is obtained.

  As described above, typical shapes are given as examples. However, other than these, a free design that satisfies the claims can be made. In particular, the shape of the boron buried layer that becomes the beam can be formed using a pattern formed on the silicon nitride film by photolithography as a mask, so a fine and complicated structure as shown in Example 2 is typical. It is also possible to make it.

It is explanatory drawing regarding Example 1 of this invention, and is A-A 'sectional drawing of FIG. It is explanatory drawing regarding Example 1 and Example 3 of this invention. It is explanatory drawing regarding Example 2 of this invention. It is explanatory drawing regarding Example 3 of this invention, and is A-A 'sectional drawing of FIG. It is explanatory drawing regarding the anisotropic etching in the case of arrange | positioning both beam structures on the back surface side by this invention. (a)-(l) is sectional drawing which shows the manufacturing method of the inkjet recording head of this invention. It is explanatory drawing regarding the prior art example at the time of arranging an ink supply port long. FIG. 8 is an invention diagram related to a conventional example when ink supply ports are arranged long, and is an XY cross-sectional view of FIG. 7. It is explanatory drawing in the case of forming a beam in an ink supply port.

Explanation of symbols

1 Silicon wafer
2 Materials used as masks for P ++ layer formation
3 P ++ layer
4 Anisotropic etching stop layer
5 Member that serves as a mask for anisotropic etching
6 Ink discharge pressure generating element
7 Dissolvable resin layer
8 Resin layer for ink flow path member
9 Discharge port
10 Ink supply port
11 Beam
12 Ink flow

Claims (3)

An ink jet recording head that is provided with an ink flow path and an ink discharge port on a substrate provided with a heating resistor, and discharges ink using the firing of the ink due to the heat generated by the heating resistor, on the substrate provided with the heating resistor A step of applying and patterning a resin of a mold material for forming the nozzle flow path, a step of applying and patterning a resin forming the ink flow path and the ink discharge port, and a step of etching the substrate to form the ink supply port In the inkjet recording head having at least the step of removing the mold material,
Either or both of the silicon substrate front side and back side of the ink supply port,
An ink jet recording head having a double beam structure formed by a member that is not etched by an etching solution for the etching. 2. The ink jet head according to claim 1, wherein the member forming the both beam structures is silicon containing 10 ²⁰ / cm ³ or more of a p-type impurity.   2. The ink jet head according to claim 1, wherein the beam is provided at a position where the flow of ink from the ink supply port to the ink discharge pressure generating element is not hindered.

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