JP2007136875A - Substrate for inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording-head substrate which enables a passage mold material to be prevented from being collected on the edge where a hollow side and a hollow bottom face are associated at eluting the mold material and the material to be easily eliminated while enabling the coverage nature of an etching protective film on the dug edge at forming a supply port to be improved and the etching gas to be prevented from invading through the dug edge. <P>SOLUTION: The hollow side and the hollow bottom face are associated with the angle larger than the one that is formed by the extension of the hollow side and the extension of the hollow bottom face. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate for an ink jet recording head that performs recording by discharging a liquid such as ink as droplets and attaching it to a recording material such as paper.

  An ink jet recording head applied to an ink jet recording method (liquid jet recording method) is generally a fine discharge port (orifice), a liquid flow path leading to it, and a discharge pressure generation provided in a part of the liquid flow path. A plurality of discharge pressure generation units including elements are provided. As the discharge pressure generating element, for example, an electrothermal conversion element is used, and in this ink jet recording head, a drive signal is applied to the electrothermal conversion element, whereby the electrothermal conversion element suddenly exceeds the nucleate boiling of the ink. A temperature rises to cause bubbles in the ink, and ink droplets are ejected by the pressure generated at this time. A drive signal is applied to each electrothermal conversion element in accordance with recording information, whereby ink is selectively ejected from each ejection port.

  In such an ink jet recording head, it is desired to obtain a high-definition and high-quality image. For this purpose, it is desirable that small droplets can be discharged from the discharge ports, and that the droplets can always be discharged from each discharge port at the same volume and discharge speed.

  As a method for achieving this, Patent Literature 1, Patent Literature 2, and Patent Literature 3 disclose a method in which bubbles generated by an electrothermal conversion element are made to communicate with outside air to discharge droplets. According to this method, the size of the discharged droplet is determined by the size of the discharge port and the distance between the electrothermal transducer and the orifice (hereinafter referred to as “OH distance”), and is always a substantially constant size. Small droplets can be ejected.

  In an ink jet recording head that ejects droplets by such a method, it is preferable to shorten the OH distance in order to eject smaller droplets and form a higher-definition image. Moreover, in order to make the size of the ejected droplets a desired size, it is necessary to be able to set the OH distance accurately and with good reproducibility.

  As a method for manufacturing an ink jet recording head that can set the OH distance to a predetermined distance accurately and with good reproducibility, there is a method disclosed in Patent Document 4. In this manufacturing method, the liquid flow path mold is formed of a soluble resin on the substrate on which the discharge pressure generating element is formed. Thereafter, a coating resin containing an epoxy resin that is solid at room temperature is dissolved in a solvent, and this is solvent-coated on a resin layer that can be dissolved to form a coating that forms a channel wall that partitions each liquid channel A resin layer is formed. Thereafter, a discharge port is opened in the coating resin layer. Finally, the soluble resin layer is eluted and removed.

  In addition, such an ink jet recording head is required to have high definition and high quality of the image, while high throughput is also desired. For this purpose, in order to increase the ejection frequency (driving frequency), it is necessary to refill the ink in the flow path after droplet ejection, that is, to refill the ink quickly. In order to speed up the refill, it is desired to reduce the flow resistance of the ink supply path between the supply port and the discharge port.

As described above, Patent Document 5 and Patent Document 6 are characterized in that the flow path height near the supply port is higher than the flow path height near the discharge pressure generating element as a configuration for reducing the flow resistance of the ink supply path. Inkjet recording heads and methods for manufacturing the same have been proposed. In the manufacturing methods described in these publications, the height of the flow path in the vicinity of the supply port is increased by digging a corresponding portion of the substrate between the vicinity of the supply port and the vicinity of the discharge pressure generating element. This increases the cross-sectional area of the ink supply path, thus reducing its flow resistance. As described above, the manufacturing methods described in these publications are effective techniques for realizing high throughput.
Japanese Patent Laid-Open No. 4-10940 JP-A-4-10941 JP-A-4-10942 Japanese Patent No. 3143307 JP-A-10-095119 Japanese Patent Laid-Open No. 10-034928

  However, after engraving the vicinity of the supply port to form a portion that becomes a liquid flow path, a flow path mold material is formed from a resin that can be eluted in a pattern corresponding to the formation pattern of the liquid flow path. In the manufacturing method in which the resin used as the orifice plate is coated and then formed by eluting the flow path mold material, when the flow path mold material is eluted, the corner portion where the hollow portion side surface and the hollow portion bottom surface are attached to each other This causes a problem that the flow path mold material accumulates and it is difficult to completely remove the flow path mold material (see FIG. 3I).

  In addition, when forming the supply port, although depending on the type of etching, for example, when performing crystal anisotropic etching, in order to prevent the etchant of crystal anisotropic etching from entering the nozzle portion, digging is performed. A protective film is formed on the surface of the recessed portion. As the protective film, SiN, SiO, or the like formed by plasma CVD can be used. After forming the supply port, when removing the protective film using dry etching, the coverage of the protective film deteriorates at the digging corner, so that the etching gas enters from the digging corner, and the flow path There arises a problem that the mold material and the orifice plate are etched (see FIGS. 3F and 3G).

  If the flow path mold is only etched, there will be no problem because it will be eluted later, but if the orifice plate is etched, the shape of the liquid flow path will change and stable discharge will be possible. There is a risk of disappearing.

  The present invention has been made paying attention to the above points, and when the flow path mold material is eluted, the flow path mold material is accumulated at the corner portion where the side surface of the recess and the bottom surface of the recess are attached to each other. For ink jet recording heads, which can be easily removed, and the coverage at the digging corner of the etching protective film when forming the supply port is improved, and the etching gas does not enter from the digging corner. An object is to provide a substrate.

  In order to solve the above problems, an ink jet recording head substrate according to the present invention includes a supply port to which a liquid is supplied from the outside, a discharge port for discharging the liquid, and a liquid supplied from the supply port. A liquid passage that guides the liquid to the discharge port, and a discharge pressure generation unit that is provided in a part of the liquid flow channel and generates a pressure for discharging the liquid. Formed as a through-hole in the base on which the discharge pressure generating element is formed, and a portion of the base in the vicinity of the discharge pressure generating element is dug on the surface on which the discharge pressure generating element is formed. An ink jet recording head substrate used in the manufacture of an ink jet recording head having a recess portion in which the through-hole is formed, comprising an extension line on the side surface of the recess portion and an extension line on the bottom surface of the recess portion. Angle larger than angle In wherein the side surface and the bottom surface are connected.

  This digging part is formed by physical methods such as dry etching such as chemical dry etching and reactive ion etching, wet etching such as crystal anisotropic etching, laser processing, or mechanical processing such as drilling and end milling. can do.

  In the method of manufacturing an ink jet recording head of the present invention, etching performed from the back side of the substrate is isotropic etching with nitric acid or other mixed acid, crystal anisotropic etching with an alkaline solution such as KOH or TMAH aqueous solution, or the like. Etching by chemical action may be used.

  According to the present invention, the side surface of the recess and the bottom surface of the recess are rounded so that the side surface of the recess and the bottom surface of the recess are associated with each other when the flow path mold material is eluted. The flow path mold material does not collect in the corners thus formed, and can be easily removed.

  Further, according to the present invention, the coverage at the digging corner of the etching protective film at the time of forming the supply port is improved, and the etching gas does not enter from the digging corner.

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

[First embodiment]
With reference to FIGS. 1A to 1I, a first embodiment of the present invention and a method for manufacturing an ink jet recording head will be described.

  As shown in FIG. 1A, the ink jet recording head manufactured in this embodiment has a substrate 102 on which a plurality of ejection pressure generating elements 101 that generate pressure for ejecting ink (liquid) are formed. .

  The discharge pressure generating elements 101 are arranged in a line on each side along the longitudinal direction of the digging portion 103 and arranged at a predetermined pitch, and the discharge pressure generating elements 101 in the lines on both sides are arranged at a half pitch. It is off. The substrate 102 is formed with a semiconductor circuit including a transistor for driving the ejection pressure generating element 101 and an electrode pad for electrically connecting the recording head to the recording apparatus main body side. For ease of understanding, illustration is omitted in each figure.

  FIG. 1B shows a state in which the digging portion 103 is formed by dry etching the silicon of the substrate using an ICP dry etching apparatus. A novolak-based general positive resist can be used as a mask for dry etching. A resist is formed in a predetermined pattern on the front surface of the substrate 102. Then, a portion where the supply port 110 is formed and a portion from this position to the front of the discharge pressure generating element 101 are formed by reactive ion etching.

In this etching, depressions are formed in the substrate by alternately coating and etching (ie, a deposition / etching process). The etchant is used in dry etching or wet etching. In certain embodiments, a reactive etching gas creates fluorine radicals and charged particles from SF ₆ to form volatile SiFx. This radical chemically or physically etches the substrate and physically removes the substrate material.

  In the deposition / etching process, a layer or coating is deposited on the inner surface including the sidewalls and bottom surface of the recess that is being formed. In certain embodiments, the coating is at least one of a polymer, a metal such as aluminum, an oxide, a metal oxide, and a metal nitride such as aluminum nitride.

  In one particular embodiment, the deposit is formed by using fluorocarbon gas to form a polymer on the inner surface of the recess to be formed.

In a specific embodiment of alternating deposition and etching, the etchant SF ₆ alternates with a gas that forms a coating on the surface of the recess, and the ions of the etchant are directed to the bottom surface of the recess and along the bottom surface. The coating and underlying substrate material are also physically and chemically removed.

  In certain embodiments, depending on the amount of coating deposited, the ions break the coating on the bottom surface within a few seconds. However, the coating along the sidewalls is hardly damaged during etching. In general, the deposit coated on the sidewalls has a slower etch rate than the deposit on the bottom surface that directly hits it. By this method, the side wall of the recess portion of the substrate becomes substantially vertical.

  In one particular embodiment, the etching and deposition steps are repeated alternately until some depression is formed. The duration of each etching step and deposition step ranges from about 1 second to 15 seconds. In this embodiment, after repeating the etching step and the deposition step until the depth of the recess becomes 1 μm to 20 μm, the deposition step is made longer so that more deposit is deposited on the sidewall of the recess. The side surface and the bottom surface are formed at an angle larger than an angle formed by an extension line of the side surface of the recess portion and an extension line of the bottom surface of the recess portion. A recess having a connected shape is formed.

  Next, SiN is deposited on the front side surface of the substrate 102 as a recess protection film 108 by plasma CVD, and patterned to cover a predetermined region. Through the above steps, an ink jet recording head substrate having the characteristic configuration of this embodiment is completed.

  Next, a polymethylisopropenyl ketone, which is a UV resist that can be eluted in a later step, is solvent-coated on the front surface of the substrate 102 by spin coating. The resist is exposed to UV light and developed to form the flow path mold 105.

  Next, a cation polymerization type epoxy resin, which is a negative resist, is further applied thereon to form an orifice plate 107 that constitutes a flow path wall that partitions the flow path ceiling and each flow path. The negative resist is exposed and developed using a photomask having a predetermined pattern, and the negative resist at the discharge port 111 and the electrode pad is removed.

  Next, a nozzle protection resin 106 containing a cyclized rubber is coated so as to protect the nozzle portion on the front side surface of the substrate. Then, a mask layer made of polyetheramide is provided on the back surface of the substrate 102, a resist is formed on the film, and a predetermined region corresponding to the opposite side of the central portion of the digging portion 103 on the front surface of the substrate 102 is formed. Patterning into a predetermined pattern having openings. Then, using the resist as a mask, the polyetheramide on the back surface of the substrate is removed by dry etching, and then the resist is removed. Thereby, the back surface mask layer 109 patterned so as to have an opening at the formation start position of the supply port 110 is formed.

  Next, the back surface of the substrate 102 is immersed in a mixed acid of nitric acid, hydrofluoric acid, and acetic acid, and crystal anisotropic etching is performed from the opening of the back surface mask layer 109. Then, the crystal anisotropic etching is advanced to the depression 103 on the surface on the front side of the substrate 102 to form the supply port 110 (FIG. 1G).

  Next, the portion of the recess protection film 108 exposed by the supply port 110 is removed by chemical dry etching. Next, the nozzle protecting resin 106 formed on the front side surface of the substrate is removed with xylene. Thereafter, the substrate is immersed in methyl lactate, and the UV resist constituting the flow path mold member 105 is eluted and removed by applying ultrasonic waves (FIG. 1 (i)).

  Although not shown in the drawing, a plurality of such substrates can be simultaneously formed on the silicon wafer constituting the substrate 102. Finally, the substrate is cut out from the wafer by dicing to complete the ink jet recording head.

[Second Embodiment]
With reference to FIGS. 2A to 2K, a second embodiment of the present invention, a method for manufacturing an ink jet recording head, will be described. This embodiment is different from the first embodiment in that the digging portion 103 is formed so as to individually extend from the side where the supply port is opened to the portion where the discharge pressure generating element is formed. Is a point.

  Subsequent steps can be performed in the same manner as in the first embodiment.

  According to the present embodiment, as shown in FIGS. 3F and 3G, which has been a problem until now, the coverage of the depression protective film 108 is deteriorated at the digging corner, so that the etching gas is digging angle. The problem that the material penetrates from the portion and is etched to the flow path mold material and the orifice plate does not occur, and the digging portion is extended to the immediate vicinity of the discharge pressure generating element 101, thereby the flow resistance of the ink supply path Can be effectively reduced.

Comparative example

  The steps of the comparative example are shown in FIGS.

  Although the basic process is the same as that of the embodiment, the corner portion formed by the side surface of the recess and the bottom surface of the recess is an acute angle.

  As a result, as shown in FIGS. 3 (f) and 3 (g), when removing the depression protective film 108, the coverage is poor at the corners, so that the etching gas enters from the dug corners and reaches the orifice plate. The problem of being etched, and the flow path mold material accumulated in the corners, making it difficult to remove completely (see FIG. 3 (i)).

Sectional drawing of the base | substrate in the manufacturing process of 1st Embodiment of this invention. The top view of the base | substrate in the manufacturing process of 1st Embodiment of this invention. Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.1 (b) The top view of the base | substrate in the manufacturing process of 1st Embodiment of this invention. Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.1 (d) Sectional drawing for every process of 1st Embodiment of this invention. Sectional drawing for every process of 1st Embodiment of this invention. The top view of the base | substrate in the manufacturing process of 1st Embodiment of this invention. Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.1 (h) Sectional drawing of the base | substrate of 2nd Embodiment of this invention. The top view of the base | substrate of 2nd Embodiment of this invention. Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.2 (b) The top view of the base | substrate of 2nd Embodiment of this invention. Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.2 (d) Sectional drawing for every process of 2nd Embodiment of this invention. Sectional drawing for every process of 2nd Embodiment of this invention. The top view of the base | substrate of 2nd Embodiment of this invention. Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.2 (h) Enlarged view of Fig. 2 (i) Sectional drawing cut | disconnected along the B-B 'line | wire of FIG.2 (j) Sectional view of the substrate of a conventional inkjet recording head Plan view of substrate of conventional inkjet recording head Sectional drawing cut | disconnected along the A-A 'line | wire of FIG.3 (b) Cross-sectional view of each process in the conventional example Cross-sectional view of each process in the conventional example Enlarged view of Fig. 3 (e) Enlarged view of Fig. 3 (e) Sectional view of the substrate of a conventional inkjet recording head Enlarged view of Fig. 3 (h)

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Discharge pressure generating element 102 Substrate 103 Excavation part 104 Excavation corner part 105 Channel type material 106 Nozzle protection resin 107 Liquid channel formation member (orifice plate)
108 Recessed part protective film 109 Back mask 110 Supply port 111 Discharge port 301 Etched orifice plate 302 Etching gas for membrane removal 303 Flow path mold material remaining

Claims (4)

  A supply port through which liquid is supplied from the outside, a discharge port through which the liquid is discharged, a liquid flow path that communicates with the discharge port and guides the liquid supplied from the supply port to the discharge port, and the liquid A discharge pressure generating unit that is provided in a part of the flow path and generates a pressure for discharging the liquid, and the supply port forms a discharge pressure generating element that constitutes the discharge pressure generating unit. The substrate is formed as a through-hole, and the base has a recessed portion in which a portion of the surface on which the discharge pressure generating element is formed is dug in the vicinity of the discharge pressure generating element, and the through hole is formed in a part thereof An ink jet recording head substrate for use in manufacturing an ink jet recording head comprising: the side surface and the side surface at an angle larger than an angle formed by an extension line of the side surface of the recess portion and an extension line of the bottom surface of the recess portion. The bottom is connected An ink jet recording head substrate according to claim.   The recess extends from the side of the surface where the discharge pressure generating element is formed to the portion where the supply port is formed to the portion where the discharge pressure generating element is formed for each flow path. An ink jet recording head substrate used in the manufacture of an ink jet recording head having a portion, wherein an extension line of a side surface of the recess portion, particularly a side surface existing in parallel with the liquid flow path direction, and the recess portion A base for an ink jet recording head, wherein the side surface and the bottom surface are connected at an angle larger than an angle formed by an extension line of the bottom surface. An etching method for forming the recess,
1. 1. Etching exposed portions on the surface of the substrate, coating the etched portions of the substrate, and repeating the etching and coating alternately. 2. A method comprising making the time of coating longer than the time performed in 1 after digging the recess to 1 μm to 50 μm. 3. A method comprising coating after digging the depression to 1 μm to 50 μm, and then increasing the gas flow rate or pressure used for the coating to a value higher than that performed in 1 above. 3. A method comprising repeating the etching after performing the step 2 or 3. The substrate for an ink jet recording head according to claim 1, wherein the substrate is formed by the above method.   3. The ink jet recording head substrate according to claim 1, wherein the recess is formed by any one of dry etching, wet etching, laser processing, and machining.