JP2010115828A - Nozzle substrate, liquid droplet ejecting head, liquid droplet ejecting apparatus, and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nozzle substrate or the like which has no dishing shape on the periphery of an ejection opening and can obtain a stable ejection characteristic. <P>SOLUTION: In the nozzle substrate 30 formed of silicon in which nozzles 31 for ejecting a liquid are formed by penetrating a plate, the nozzle 31 is made to have the ejection opening projected from a surface of the substrate to prevent the ejection opening periphery from being a dented dishing shape (round shape) on an ejection surface of liquid droplets. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a nozzle substrate on which nozzles are formed by microfabrication, a droplet discharge head that discharges droplets of ink or the like, a droplet discharge device, and a method for manufacturing the same.

  For example, micro electro mechanical systems (MEMS) that process silicon or the like to form minute elements or the like have made rapid progress. Examples of microfabricated elements formed by microfabrication technology include, for example, a droplet discharge head (inkjet head), a micropump, and an optical variable filter used in a recording (printing) apparatus such as a droplet discharge type printer. There are electrostatic actuators such as motors, pressure sensors and the like.

  Here, a droplet discharge head will be described as an example of a microfabricated element. A droplet discharge type recording (printing) apparatus is used for printing in various fields regardless of whether it is for home use or industrial use. The droplet discharge method is, for example, a method in which a droplet discharge head having a plurality of nozzles is moved relative to an object (paper, etc.), and droplets are discharged to a predetermined position of the object for printing or the like. It is. This system is a microarray of biomolecules such as color filters for producing display devices using liquid crystals, display panels (OLEDs) using electroluminescent devices such as organic compounds, DNA, proteins, etc. Etc. are also used in the manufacture of

  As a method of ejecting droplets from a nozzle by a droplet ejection head, for example, there is a method in which a liquid is heated and droplets are ejected by the pressure of generated air (bubbles). Also, a discharge chamber for storing liquid is provided in a part of the flow path, and at least one wall of the discharge chamber (here, referred to as a bottom wall, hereinafter referred to as a diaphragm) is bent. There is a method in which (in operation) the pressure in the discharge chamber is increased by shape change, and droplets are discharged from the communicating nozzle. In addition, the diaphragm is a movable electrode, a voltage is applied between the electrode (fixed electrode) facing the diaphragm at a distance, and the generated electrostatic force (electrostatic attractive force is often used. In some cases, the diaphragm is displaced by the generated electrostatic attraction and discharged by the pressure.

  Here, consider a nozzle substrate having nozzles for ejecting liquid as droplets. The nozzle substrate is manufactured mainly by performing anisotropic etching on a silicon substrate. As anisotropic etching, there are dry etching (dry etching) and wet etching (wet etching). For example, a hole to be a nozzle is formed to a desired depth by dry etching, a recess is formed by wet etching from the surface opposite to the surface on which the nozzle hole is formed, and the nozzle length is adjusted. The nozzle outlet is opened on the bottom of the recess (see, for example, Patent Document 1). Here, in order to improve discharge performance (stabilize discharge characteristics), the shape of the nozzle is often formed in two or more steps close to a tapered shape.

In some cases, after adjusting the thickness of the substrate in advance by grinding and polishing, nozzles are formed by performing dry etching on both sides of the substrate (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 11-28820 (FIGS. 3 and 4) Japanese Patent Laid-Open No. 9-57981 (FIGS. 1 and 2)

  However, when the nozzle substrate is manufactured according to the procedure described in Patent Document 1, the bottom surface of the recess that is lowered by one step from the surface of the nozzle substrate becomes the discharge surface where the nozzle discharge port is opened. In wet etching, the surface often becomes rough, and thus the flight of the droplets may be bent due to variations in the discharge port opening. Also, when wiping work to wipe the discharge surface with rubber pieces or felt pieces, etc., to remove paper dust, liquid, etc. that cause clogging of the nozzle holes from the discharge surface, the discharge surface is at the bottom of the recess. And work becomes difficult.

  On the other hand, as the density of the nozzles of the droplet discharge head increases, the thickness of the nozzle substrate must be further reduced. In such a case, if the nozzle substrate as in Patent Document 2 is manufactured, there is a high possibility that the substrate will break during the manufacturing process, and the yield will be lowered. There is a possibility. Furthermore, when dry etching is performed, cooling with helium (He) gas or the like is performed from the back side of the substrate so that the processing shape is stabilized. However, when the nozzle hole is penetrated, He gas leaks and etching becomes impossible. was there.

  Therefore, after forming a recess to be a nozzle in advance, a method of manufacturing a nozzle substrate by grinding and polishing from a surface opposite to the surface on which a hole to be a nozzle is formed, and opening a nozzle discharge port Is also considered. However, due to the thinning process, the periphery of the discharge port, which is the tip of the nozzle on the droplet discharge surface, may be recessed with respect to the droplet discharge surface, resulting in a dishing shape (round shape). Therefore, for example, when performing plasma treatment to remove the liquid repellent layer on the inner wall of the nozzle, the protective film that protects the liquid repellent layer on the droplet discharge surface is not in close contact with the periphery of the discharge port, and the liquid repellent layer is damaged. As a result, the liquid repellency is lowered and the ejection characteristics may not be stable.

  Accordingly, an object of the present invention is to obtain a nozzle substrate or the like that can obtain a stable discharge characteristic by avoiding the dishing shape around the discharge port. Moreover, it aims at obtaining the manufacturing method suitable for it.

The nozzle substrate according to the present invention is a nozzle substrate made of silicon, in which a nozzle for discharging a liquid is formed by penetrating a flat plate, and the nozzle has a discharge port protruding from the substrate surface.
According to the present invention, since the discharge port serving as the tip portion of the nozzle protrudes from the surface of the substrate, the liquid near the discharge port of the nozzle is more easily drawn, so that the liquid does not accumulate, flight bending, etc. It is possible to obtain a nozzle substrate in which the discharge characteristics of droplets discharged from the discharge ports are stable.

In the nozzle substrate according to the present invention, the nozzle is formed in a tapered shape or a multi-stage shape in which the hole diameter decreases in the direction in which the liquid droplets are ejected.
According to the present invention, since the nozzles are formed in a tapered shape or in a plurality of stages, it is possible to improve the straightness of the liquid droplets to be discharged, and to improve and stabilize the discharge performance.

In the nozzle substrate according to the present invention, the nozzle discharge port protrudes 0.1 to 1.6 μm from the surface of the substrate.
According to the present invention, since the discharge port of the nozzle protrudes 0.1 to 1.6 μm from the surface of the substrate, an effective wiping operation is performed while stabilizing discharge characteristics, and paper dust or the like is removed. Can be wiped off.

In addition, a liquid droplet ejection head according to the present invention includes the above-described nozzle substrate, a flow path substrate having a flow path for supplying liquid to the nozzles of the nozzle substrate, and a pressure for pressurizing the liquid in the flow path substrate. Pressure means.
According to the present invention, since the nozzle substrate described above is provided and the pressurized liquid is ejected, a droplet ejection head having stable ejection characteristics can be obtained.

Moreover, the droplet discharge apparatus according to the present invention is equipped with the above-described droplet discharge head.
According to the present invention, since the above-described droplet discharge head is provided and liquid is discharged, a droplet discharge device having stable discharge characteristics can be obtained.

The method for manufacturing a nozzle substrate according to the present invention includes a step of performing anisotropic dry etching from one surface side of a silicon substrate to form a recess to be a nozzle, and a silicon oxide film is formed at least in the recess. Fixing the silicon substrate with the surface where the recess is formed facing the support substrate, grinding and polishing the silicon substrate from the surface opposite to the surface where the recess is formed, and forming a hole through the recess And a step of forming a nozzle having a frustoconical shape with a tip portion protruding from the surface of the substrate to protrude from the surface of the substrate.
According to the present invention, the silicon oxide film is formed in the recess, and the silicon substrate is ground and polished from the surface opposite to the surface on which the recess is formed. As a result, the tip portion forms a frustoconical nozzle, so that the liquid around the discharge port of the nozzle is more easily drawn and the discharge characteristics can be stabilized.

The method for manufacturing a nozzle substrate according to the present invention also includes a step of forming a water-repellent layer by performing a water-repellent treatment on the silicon substrate on which the nozzle is formed, and protecting the water-repellent layer on the surface on which the discharge port is formed. And a step of performing a plasma treatment for removing the water-repellent layer on the inner wall of the nozzle.
According to the present invention, the water-repellent layer formed by the water-repellent treatment is formed, and the protective film is closely adhered to the nozzle outlet and closed and sufficiently protected, and then the plasma treatment is performed to perform the water-repellent layer on the inner wall of the nozzle. Thus, the nozzle substrate can be formed without damaging the water-repellent layer on the surface on which the droplets are ejected. Therefore, it is possible to sufficiently exhibit the water repellent effect and further stabilize the ejection characteristics.

Further, in the method for manufacturing a nozzle substrate according to the present invention, the concave portions to be the nozzles are formed so as to have a plurality of steps in which the hole diameter decreases in the direction in which the liquid is discharged.
According to the present invention, since the nozzles are formed in a tapered shape or in a plurality of stages, it is possible to improve the straightness of the droplets to be discharged and improve the discharge characteristics.

In the method for manufacturing a nozzle substrate according to the present invention, the nozzle is formed by polishing by CMP using only the slurry for silicon polishing.
According to the present invention, since polishing is performed using only a slurry for polishing silicon, a tip having a truncated cone shape is formed particularly on the basis of the difference in polishing rate (rate) with silicon oxide. can do.

Further, in the method for manufacturing a nozzle substrate according to the present invention, when polishing, the type and / or weight of the polishing pad is adjusted to adjust the height at which the portion serving as the discharge port protrudes.
According to the present invention, the height at which the portion that becomes the discharge port protrudes is adjusted by adjusting the type and / or weight of the polishing pad, so the height at which the nozzle protrudes is controlled to a desired height. can do.

In addition, the method for manufacturing a droplet discharge head according to the present invention includes a nozzle substrate manufactured by the above method, a channel for supplying liquid to the nozzles of the nozzle substrate, and a liquid added to a part of the channel. And a step of bonding a substrate provided with a pressing means for pressing.
According to the present invention, since the droplet discharge head is manufactured using the nozzle substrate manufactured by the above-described manufacturing method, a droplet discharge head with stable discharge characteristics can be manufactured.

In addition, a method for manufacturing a droplet discharge device according to the present invention is a method for manufacturing a droplet discharge device by applying the method for manufacturing a droplet discharge head described above.
According to the present invention, since the droplet discharge device is manufactured using the droplet discharge head manufactured by the above-described manufacturing method, a device with stable discharge characteristics can be manufactured.

Embodiment 1 FIG.
FIG. 1 is an exploded view of a droplet discharge head according to a first embodiment of the present invention. FIG. 1 shows a face eject type liquid droplet ejection head as a representative of an electrostatic actuator. (For the sake of clarity, the components are shown in the following drawings including FIG. May be different from the actual relationship, and the upper side of the figure is the upper side and the lower side is the lower side). In FIG. 1, the electrode substrate 10 has a thickness of about 1 mm. In FIG. 1, the electrode substrate 10 is bonded to the lower surface of the cavity substrate 20 so as to face the diaphragm 22. In the present embodiment, a borosilicate heat-resistant hard glass is used as a material for the substrate constituting the electrode substrate 10. The electrode substrate 10 is provided with, for example, a groove portion 11 having a depth of about 0.25 μm in accordance with each discharge chamber 21 formed in the cavity substrate 20, and an individual electrode 12 </ b> A facing each discharge chamber 22 on the inner side (particularly the bottom portion). The lead portion 12B and the terminal portion 12C (hereinafter referred to as the electrode portion 12 when they are not particularly distinguished) are provided. In the present embodiment, ITO (Indium Tin Oxide) doped with indium with tin oxide as an impurity is used as the material of the electrode portion 12, and the bottom surface of the groove portion 11 is, for example, 0.1 μm by sputtering or the like. A film is formed with a thickness. The liquid supply port 13 serves as an intake port for supplying liquid such as ink from an external tank (not shown) to the droplet discharge head.

  The cavity substrate 20 serving as a flow path substrate is made of, for example, a silicon single crystal substrate (including this substrate, hereinafter simply referred to as a silicon substrate) having a (110) plane orientation. The cavity substrate 20 is provided with a concave portion (a bottom wall becomes a vibration plate 22 serving as a driven portion) serving as a discharge chamber 21 for temporarily storing a liquid to be pressurized and discharged, and a liquid discharged in common to each nozzle. A recess serving as a reservoir 23 is formed. For example, an anisotropic wet etching method (hereinafter referred to as wet etching) is used to form the recess. The reservoir 23 temporarily stores the liquid supplied via the liquid supply port 13 and supplies the liquid to each discharge chamber 22. The common electrode terminal 24 provided on the cavity substrate 1 is for supplying the cavity substrate 20 with a charge opposite to the charge supplied to the electrode portion 12. Further, in order to insulate the individual electrode 12 </ b> A from the diaphragm 22, an insulating film 25 made of silicon oxide or the like is formed on the lower surface of the diaphragm 22. Although not particularly illustrated, a liquid protective film that protects the cavity substrate 20 from the discharge liquid or the like may be formed on the side where the concave portion or the like that becomes the discharge chamber 21 is provided.

  The nozzle substrate 30 is bonded to the cavity substrate 20 on the surface opposite to the electrode substrate 10 (upper surface in the case of FIG. 1). The nozzle substrate 30 of the present embodiment is assumed to have a plurality of nozzles 31 formed in two stages that communicate with the discharge chamber 21. A cylindrical nozzle having a discharge port of a smaller diameter (about 20 μm) on the liquid discharge side, which is opened so as to be circular on the outer surface (upper surface in the case of FIG. 1) of the nozzle substrate 30, is provided. One nozzle is 31A. In addition, a circle having a larger diameter (about 50 μm) on the liquid supply side, opened to be circular on the inner surface (the surface facing the cavity substrate 20, the lower surface in FIG. 1). The columnar nozzle is referred to as a second nozzle 31B. Here, it is assumed that the centers of the circles formed by the first nozzle 31A and the second nozzle 31B are the same (concentric circles). In addition, a narrow groove serving as an orifice 32 is provided on the inner surface, and the discharge chamber 21 and the reservoir 23 are communicated with each other to serve as a communication groove for supplying the liquid stored in the reservoir 23 to the discharge chamber 21. Although not particularly shown here, for example, a diaphragm for buffering the force propagating to the liquid stored in the reservoir 23 by pressurizing the diaphragm 22 may be provided. In FIG. 1, the nozzle substrate 30 is the upper surface and the electrode substrate 20 is the lower surface. However, when actually used, the nozzle substrate 30 is usually lower than the electrode substrate 20.

  FIG. 2 is a cross-sectional view of the droplet discharge head. The terminal portion 12 </ b> C is exposed to the outside at the electrode outlet 26. The oscillation circuit 41 is electrically connected to the terminal portion 12C and the common electrode terminal 24 directly or via a wire 42 such as a wire or FPC (Flexible Print Circuit), and the individual electrode 12A, the cavity substrate 20 (the diaphragm 22). ) Is a circuit for controlling supply and stop of electric charge (electric power). The oscillation circuit 41 oscillates to supply charges by applying, for example, a pulse voltage to the individual electrode 12A. The oscillation circuit 41 oscillates and drives the individual electrodes 12A selectively to charge them positively or negatively, and to charge the diaphragm 22 relatively negative in negative phase. At this time, the diaphragm 22 is attracted to the individual electrode 12A by the electrostatic force and bent. This increases the volume of the discharge chamber 21. When the charge supply is stopped, the diaphragm 22 returns to its original state, but at that time, the volume of the discharge chamber 21 also returns to its original state, and droplets are discharged by the pressure. For example, printing is performed by the droplets landing on an ejection target. In order to prevent the space (gap) between the individual electrode 12A and the diaphragm 22 from communicating with the outside air by exposing the terminal portion 12C to the outside, the sealing material 27 is used to seal and block the outside air. Yes.

  In the present embodiment, on the surface of the nozzle substrate 30 on the droplet discharge side, the portion provided with the droplet discharge port by the first nozzle 31A is the surface portion of the surface from which the droplet is discharged (of the droplet discharge head). ) So that the dishing shape (round shape) is not recessed. Therefore, silicon oxide is formed in advance on at least the side wall portion of the nozzle 31A. Then, for example, the substrate is ground to adjust the length of the nozzle 31, and when polishing is performed as the final adjustment, polishing is performed with a slurry for silicon polishing. Since the degree of polishing is different between silicon and silicon oxide, it is possible to prevent silicon oxide from excessively polishing the silicon around the discharge port and to prevent the formation of a dishing shape. In addition, since silicon remains in a continuous form around the silicon oxide where polishing is delayed, the edge portion (tip portion) of the nozzle 31 can be formed in a truncated cone shape (reverse dishing shape). As a result, it is possible to obtain a nozzle substrate 30 (droplet discharge head) that can make the discharge port portion protrude from the substrate surface, have good liquid drawing, and can stabilize discharge characteristics.

  3 to 6 are diagrams illustrating a method for manufacturing the nozzle substrate 30 according to the first embodiment. Next, based on FIGS. 3-6, the procedure of the preparation method of the nozzle substrate 30 in this invention is demonstrated. In practice, a plurality of nozzle substrates 30 of a droplet discharge head are simultaneously formed from a silicon wafer, but only a portion for forming a nozzle 31 is shown in FIGS. 3 to 6. Here, the following description will be made with specific numerical values, but these numerical values represent an example and are not limited to these values.

  First, when etching is performed on a silicon substrate 51 having a thickness of about 280 μm, a silicon oxide film 52 serving as a film (resist) for protecting the silicon substrate 51 is formed on the entire surface, for example, about 1 μm (FIG. 3A). . The film forming method is not particularly limited, but here, for example, a thermal oxidation method is used in which the silicon substrate 51 is exposed to an oxygen and water vapor atmosphere at a high temperature (about 1075 ° C.).

  Then, in order to selectively etch the silicon oxide film 52 and perform patterning, a photosensitizing agent that becomes the photoresist film 53 is applied using a photolithography method. Then, a portion of the photoresist film 53 that becomes the second nozzle 31B is removed by exposure and development, and pattern formation (patterning) is performed (FIG. 3B). Then, for example, a silicon oxide film in a portion to be the second nozzle 31B is immersed in a hydrofluoric acid aqueous solution, a buffered hydrofluoric acid aqueous solution (BHF: for example, a liquid in which a hydrofluoric acid aqueous solution and an ammonium fluoride aqueous solution are mixed at 1: 6) or the like. 52 is removed by half etching (FIG. 3C). The silicon oxide film 52 in the portion that becomes the second nozzle 31B is not removed by half etching, and silicon is not exposed. At this time, half etching is also performed on the back surface on the side where the portion to be the second nozzle 31B is formed. Then, the photoresist film 53 is removed by washing with sulfuric acid or the like (FIG. 3D).

  Then, a photoresist film 54 is formed again, and the photoresist film 54 in the portion that becomes the first nozzle 31A and the portion that becomes the orifice 32 is removed, and pattern formation (patterning) is performed (FIG. 3E). Similarly to the case where the silicon oxide film 52 in the portion serving as the second nozzle 31B is removed, the silicon oxide film 52 in the portion serving as the first nozzle 31A is removed by half etching (FIG. 3F). At this time, a portion of silicon that becomes the first nozzle 31A is exposed. Also, the silicon oxide film 52 is completely removed from the back surface to expose silicon. Then, the photoresist film 54 is removed by washing with sulfuric acid or the like (FIG. 4G).

Next, dry etching is performed to form, for example, a recess (hole) having a diameter of about 20 μm and a depth of about 25 μm in the first nozzle 31A (FIG. 4H). The type of dry etching or the like is not particularly limited. For example, dry etching by ICP (Inductively Coupled Plasma) discharge may be performed. In this case, the etching is alternately repeated in the depth direction with SF ₆ (sulfur hexafluoride) while protecting the side wall surface with, for example, fluorine-based C ₄ F ₈ (Kutafluorocyclobutane) as a gas used for etching. Then, dry etching is performed. Then, the silicon oxide film 52 in the portion that becomes the second nozzle 31B and the portion that becomes the orifice 32 left by the half etching is removed by photolithography or the like (FIG. 4I).

  Further, dry etching is performed to form a recess (hole) having a diameter of about 50 μm and a depth of 40 μm with respect to the second nozzle 31B. About the part of the 1st nozzle 31A, a recessed part will be formed to a 40-micrometer deep part. Further, the orifice 32 is simultaneously formed by dry etching (FIG. 4 (j)). Again, the type of dry etching is not particularly limited. When dry etching is completed, the silicon oxide film 52 formed as a protective film is removed. The removal of the silicon oxide film 52 is performed, for example, by wet etching the entire surface with the above-described hydrofluoric acid aqueous solution or the like.

  Then, a silicon oxide film 55 is formed on the entire surface (FIG. 4K). Here, for example, a 0.1 μm film is formed on the entire surface by using a dry thermal oxidation method in which the silicon substrate 51 is exposed to an oxygen atmosphere at about 1000 ° C. for 2 hours.

  Then, the etched surface 51A of the silicon substrate 51 and the support substrate 61 are bonded and fixed with, for example, a double-sided tape 62 (FIG. 5L). The double-sided tape 62 is not particularly limited. For example, the double-sided tape 62 may be a tape having a self-peeling layer whose adhesive strength (adhesive strength) is reduced by heat, ultraviolet rays, or the like. In the present embodiment, for example, a double-sided tape 62 provided on both sides with a UV curable adhesive layer 63 whose adhesive strength is weakened by ultraviolet irradiation is used. Here, if bubbles are included in the adhesive interface, the plate thickness may vary during polishing. Therefore, the UV curable adhesive layer 63 of the double-sided tape 62 bonded to the support substrate 61 and the support substrate 61 face each other. Bonding is performed in a vacuum so that bubbles are not left at the bonding interface so that clean bonding is performed.

  The silicon substrate 51 is ground by a back grinder (not shown) from the surface opposite to the surface bonded to the support substrate 61 with the double-sided tape 62 until the thickness becomes slightly larger than the desired plate thickness. Here, grinding is performed until the plate thickness is about 71 μm. Further, polishing is performed to a predetermined plate thickness (about 65 μm) by a polisher and a CMP (Chemical Mechanical Polishing) apparatus (FIG. 5 (m)). Here, polishing is performed using a slurry for silicon polishing without polishing by a dry polisher. This polishing step will be described later.

  On the droplet discharge surface 51B of the silicon substrate 51, an ink-resistant protective film and an oxide-based metal film serving as a base for the liquid repellent layer are formed. In this embodiment, a silicon oxide film 56 having a thickness of 0.1 μm is formed by sputtering (FIG. 5 (n)). Here, the silicon oxide film 56 (oxide-based metal film) is formed by sputtering, but the UV curing adhesive layer 63 is not deteriorated and the temperature (at which the adhesiveness with the silicon substrate 51 can be secured). The sputtering method is not limited as long as the film can be formed at a temperature of about 100 ° C. or less. Further, for example, a hafnium oxide film, tantalum oxide, titanium oxide, indium tin oxide, zirconium oxide, or the like can be used as the material of the oxide-based metal film.

  Further, a liquid repellent treatment is performed on the surface of the droplet discharge surface 51B on which the silicon oxide film 56 is formed. A liquid repellent material containing fluorine (F) atoms is deposited by vapor deposition, dipping, etc., to form a liquid repellent layer 57 (FIG. 5 (o)). By this liquid repellent treatment, the liquid repellent layer 57 is also formed on the inner wall of the nozzle 31 which is not necessarily formed.

  A protective film 64 is affixed to the droplet discharge surface 51B of the silicon substrate 51 (FIG. 5 (p)). Here, in the figures after FIG. 5 (p), the substrate is turned upside down. Then, ultraviolet light is irradiated from the support substrate 61 side (FIG. 6 (q)), the UV curable adhesive layer 63 of the double-sided tape 62 is cured, and the support substrate 61 and the silicon substrate 51 are separated (FIG. 6 (r)). )).

Then, the Ar plasma treatment or 0 ₂ plasma treatment to the surface 51A subjected to etching, extra-formed removed liquid-repellent layer 57 of the inner wall surface of the nozzle 31 (ashing). In this embodiment, Ar plasma treatment is performed (FIG. 6 (s)). Thereafter, when the nozzle substrate 30 is bonded to the cavity substrate 20, in order to increase the adhesive strength, the nozzle substrate 30 is immersed in a primer treatment solution for 1 hour, rinsed with pure water, baked at 80 ° C. for 1 hour, and dried. Here, for example, a silane coupling agent is used as the primer treatment liquid.

  The protective film 64 attached to the silicon substrate 51 is peeled off (FIG. 6 (t)). Then, by cutting (dicing) using a cutter or the like, the silicon substrate 51 is divided into each nozzle substrate 30 to form individual pieces (chips), and the nozzle substrate 30 is manufactured (FIG. 6 (u)).

  FIG. 7 is a diagram showing the shape of the nozzle edge (discharge port) portion of the nozzle 31 formed by polishing the droplet discharge surface 51B. Here, the polishing process by CMP shown in FIG. In the step of thinning the silicon substrate 51, polishing is usually performed using a dry polisher. In this case, as shown in FIG. 7A, on the droplet discharge surface 51B, the peripheral portion of the discharge port of the nozzle 31 has a dishing shape (concave shape), and a portion opened as the discharge port of the nozzle 31 is formed. It was a position (a recessed position) where 0.3 to 1.4 μm entered from the droplet discharge surface 51B.

  FIG. 8 is a view for showing the close contact between the protective film 64 and the silicon substrate 51. As described above, if the amount of penetration (hereinafter referred to as dishing amount) from the droplet discharge surface 51B of the discharge port is large (the dent is large) due to the dishing shape, the droplet discharge surface 51B and the protective film 64 in the peripheral portion of the discharge port The adhesive layer 64A is not in close contact. Therefore, in FIG. 6 (s), when performing the plasma processing step of removing the liquid repellent layer 57 on the inner wall surface of the nozzle 31, the protective film 64 cannot block the discharge port, and the droplet discharge in the portion around the discharge port is performed. The surface 51B cannot be effectively protected, and Ar wraps around and damages the liquid repellent layer 57 on the droplet discharge surface 51B. Therefore, the liquid repellent layer 57 around the discharge port is removed, and the liquid repellent effect cannot be exhibited.

  Therefore, in the present embodiment, only the polishing slurry for silicon is used in the polishing by CMP shown in FIG. At this time, a flexible polishing pad is selected to control the weight during polishing. Since the slurry is for polishing silicon, silicon oxide is slower in polishing than silicon. For this reason, the polishing of the silicon oxide film 55 formed on the inner wall surface of the nozzle 31 is delayed. Further, the silicon in the vicinity of the silicon oxide film 55 and in the vicinity of the discharge port, which is in the vicinity of the silicon oxide film 55, is also difficult to be polished. This not only prevents the peripheral portion of the discharge port on the droplet discharge surface 51B from being excessively polished, but also increases the height around the discharge port of the nozzle 31 (reverse dishing) as shown in FIG. Amount) A convex shape (conical truncated cone shape, mountain shape) of 0.1 to 1.6 μm is formed, and the discharge port serving as the edge portion of the nozzle 31 can be protruded from the droplet discharge surface 51B. Since the tip portion of the nozzle 31 has a minute convex shape, the liquid discharged from the discharge port is more easily drawn, and the discharge characteristics can be stabilized.

  Here, in the polishing step, the height of the convex shape to be formed can be made different by changing the type and weight of the polishing pad used as described above and making the polishing condition of the silicon oxide film 55 different. The type and weight of the polishing pad are not particularly limited, but in this embodiment, the polishing pad is adjusted so that the Wf pressure is 11.5 kPa, the weight is increased, and the polishing amount by CMP is 5 .8 μm. At this time, the polishing rate (rate) is set to 0.5 μm / min.

  Further, regarding the close contact with the protective film 64, as shown in FIG. 8B, the discharge port from which the adhesive layer 64A of the protective film 64 protrudes is closed, and the portion around the discharge port of the droplet discharge surface 51B and the protective film. Even when the 64 adhesive layers 64A are in close contact with each other and plasma treatment is performed, the liquid repellency of the liquid repellent layer 57 in the peripheral portion of the liquid discharge surface 51B is no longer impaired.

  FIG. 9 is a diagram illustrating a manufacturing process of the droplet discharge head. Based on FIG. 9, the manufacturing process of the liquid droplet ejection head including the production of another substrate will be described. Actually, a plurality of droplet discharge head members are simultaneously formed from a silicon wafer, but only a part thereof is shown in FIG.

  A groove 11 having a depth of 0.2 μm is formed in accordance with the shape pattern of the electrode portion 12 on one surface of a glass substrate of about 1 mm to be the electrode substrate 10. Then, using a method such as sputtering, ITO having a thickness of 0.1 μm is formed on the inner side (particularly the bottom wall) of the groove 11 to form the electrode 12. Further, the liquid supply port 13 is formed by a sandblasting method or a cutting process. Thereby, the glass substrate 10 is produced (FIG. 9A).

As for the substrate to be the cavity substrate 20, first, for example, one surface of the silicon substrate 71 having a low oxygen concentration with a (110) plane orientation is mirror-polished to a thickness of 220 μm. Next, the surface on which the boron dope layer 72 is formed on the silicon substrate 71 is set on a quartz boat so as to face a solid diffusion source mainly composed of B ₂ O ₃ . Further, a quartz boat is set in a vertical furnace, and the inside of the furnace is made into a nitrogen atmosphere. For example, the temperature is raised to 1050 ° C. and held for 7 hours to diffuse boron into the silicon substrate 71 to form a boron doped layer 72. . At this time, a boron compound is formed on the surface of the boron dope layer 72 (not shown), but it can be etched with a hydrofluoric acid aqueous solution by oxidizing for 1 hour 30 minutes in an oxygen and water vapor atmosphere at 600 ° C. It is chemically changed to B ₂ O ₃ + SiO ₂ and removed by wet etching with a hydrofluoric acid aqueous solution. Further, the insulating film 25 is formed on the surface on which the boron doped layer 72 is formed by plasma CVD (FIG. 9B). The insulating film 25 is formed by plasma CVD, for example, at a processing temperature of 360 ° C., a high frequency output of 250 W, a pressure of 66.7 Pa (0.5 Torr), a gas flow rate of TEOS flow rate 100 cm ³ / min (100 sccm), A 0.1 μm film is formed under the condition of an oxygen flow rate of 1000 cm ³ / min (1000 sccm).

  Next, after heating the silicon substrate 71 and the electrode substrate 10 to 360 ° C., a negative electrode is connected to the electrode substrate 10 and a positive electrode is connected to the silicon substrate 71, and an anodic bonding is performed by applying a voltage of 800V. Then, in the bonded substrate after anodic bonding, the surface of the silicon substrate 71 is ground until the silicon substrate 71 has a thickness of about 60 μm. Thereafter, in order to remove the work-affected layer, the silicon substrate 71 is wet-etched by about 10 μm with a potassium hydroxide solution having a concentration of 32 w%, for example. As a result, the thickness of the silicon substrate 71 is reduced to about 50 μm (FIG. 9C).

For example, a silicon oxide film 73 serving as an etching mask is formed on the wet etched surface by a plasma CVD method using TEOS. The film formation conditions for the silicon oxide film 73 include, for example, a processing temperature of 360 ° C., a high frequency output of 700 W, a pressure of 33.3 Pa (0.25 Torr), and a gas flow rate of TEOS flow rate 100 cm ³ / min (100 sccm). ), And a film thickness of 1.5 μm is formed under the condition of oxygen flow rate of 1000 cm ³ / min (1000 sccm). Film formation using TEOS can be performed at a relatively low temperature, and heating of the substrate can be suppressed as much as possible. Further, using the photolithography method, portions of the silicon oxide film 73 which become the discharge chamber 21, the reservoir 23, and the electrode outlet 26 are removed by etching (FIG. 9D). Here, for example, silicon is exposed in portions that become the discharge chamber 21 and the electrode outlet 26, and the silicon oxide film 73 is left in the reservoir 23 by half etching. This is because the portion that becomes the reservoir 23 is made rigid by leaving silicon.

  Next, the bonded substrate is immersed in a 35 wt% potassium hydroxide aqueous solution, and wet etching is performed until the thickness of the portion that becomes the discharge chamber 21 becomes about 10 μm. Further, the bonded substrate is immersed in a 3 wt% concentration potassium hydroxide aqueous solution, and etching is continued until it is determined that the etching stop is sufficiently effective in the boron doped layer 72. Thus, by performing wet etching using the two types of potassium hydroxide aqueous solutions having different concentrations, the surface roughness of the diaphragm 22 to be formed is suppressed, and the thickness accuracy is 0.80 ± 0.05 μm or less. can do. As a result, the discharge performance of the droplet discharge head can be stabilized (FIG. 9 (e)). When the wet etching is completed, the bonded substrate is immersed in, for example, a hydrofluoric acid aqueous solution, and the silicon oxide film 73 on the surface of the silicon substrate 71 is removed (FIG. 9F).

  The silicon (boron doped layer 72) in the portion that becomes the electrode outlet 26 of the silicon substrate 71 is removed and opened. The removal method is not particularly limited. For example, it can be broken by a pin or the like. Moreover, it can also open by performing dry etching. Thereafter, sealing is performed by pouring, for example, epoxy resin or depositing silicon oxide along the opening of the gap formed between the cavity substrate 20 and each recess 11 at the end of the electrode outlet 26. A stopper 27 is formed and sealed, and the gap is shielded from the outside air (FIG. 9G). Here, although not particularly illustrated, for example, a silicon oxide film for protecting the liquid may be formed on the upper surface of the cavity substrate 20 by plasma CVD using TEOS, for example.

  When the sealing is completed, for example, a mask having an opening at a portion to be the common electrode terminal 24 is attached to the surface of the bonding substrate on the silicon substrate 71 side. Then, for example, sputtering is performed using platinum (Pt) as a target to form the common electrode terminal 24. Then, the above-described nozzle substrate 30 produced in a separate process is bonded and bonded from the cavity substrate 20 side of the bonded substrate, for example, with an epoxy adhesive (FIG. 9H). Then, dicing is performed along the dicing line, and cutting into individual droplet discharge heads is completed.

  As described above, according to the first embodiment, the discharge port of the nozzle 31 is set to be smaller than the surface of the droplet discharge surface 51B by the polishing process performed to make the silicon substrate 51 serving as the nozzle substrate 30 have a predetermined thickness. Since the tip portion of the nozzle 31 has a convex shape, the liquid at the periphery of the discharge port of the nozzle 31 is better drawn and the discharge characteristics can be stabilized. In addition, since the protective film 64 for protecting the liquid repellent layer 57 on the droplet discharge surface 51B in the plasma treatment step can be adhered to the discharge port, the liquid repellent layer 57 on the droplet discharge surface 51B is formed in the plasma treatment step. The liquid repellency can be maintained without being damaged, and the ejection characteristics can be further stabilized. Since only the silicon polishing slurry is used, the polishing of the silicon oxide film 55 is delayed from the polishing of the silicon of the silicon substrate 51 to form the nozzle 31 having a discharge port portion (tip portion) having a convex shape. can do. At this time, a desired convex nozzle 31 can be formed by controlling the type and weight of the polishing pad.

Embodiment 2. FIG.
The droplet discharge head in the above-described embodiment is configured by laminating three substrates of the electrode substrate 10, the cavity substrate 20, and the nozzle substrate 30, but the present invention is not limited to this. For example, in order to increase the volume of the reservoir 23, the present invention can also be applied to a droplet discharge head having a configuration in which a recess serving as the reservoir 23 is formed on an independent substrate and four substrates are stacked.

  In the above-described embodiment, the liquid droplet discharge head that pressurizes the liquid by displacing the vibration plate 22 by the electrostatic force generated between the vibration plate 22 and the individual electrode 12 and discharges the liquid droplets from the nozzle 31 has been described. . The present invention is not limited to this. For example, the present invention can also be applied to a droplet discharge head using another pressurization method such as generating gas or using a piezoelectric element.

Embodiment 3 FIG.
FIG. 10 is an external view of a droplet discharge apparatus using the droplet discharge head manufactured in the above embodiment. FIG. 11 is a diagram illustrating an example of main constituent means of the droplet discharge device. 10 and 11 is intended for printing by a droplet discharge method (inkjet method). Further, it is a so-called serial type device. In FIG. 11, a drum 101 that supports a printing paper 100 that is a substrate to be printed and a droplet discharge head 102 that discharges ink onto the printing paper 100 and performs recording are mainly configured. Although not shown, there is an ink supply means for supplying ink to the droplet discharge head 102. The print paper 110 is held by being pressed against the drum 101 by a paper press roller 103 provided parallel to the axial direction of the drum 101. A feed screw 104 is provided parallel to the axial direction of the drum 101, and the droplet discharge head 102 is held. As the feed screw 104 rotates, the droplet discharge head 102 moves in the axial direction of the drum 101.

  On the other hand, the drum 101 is rotationally driven by a motor 106 via a belt 105 or the like. Further, the print control unit 107 drives the feed screw 104 and the motor 106 based on the print data and the control signal, and although not shown here, drives the oscillation drive circuit to vibrate the diaphragm 22, Printing is performed on the print paper 110 while controlling.

  Here, the liquid is ejected onto the print paper 110 as ink, but the liquid ejected from the droplet ejection head is not limited to ink. For example, in an application to be discharged onto a substrate to be a color filter, a liquid containing a pigment for a color filter, an application to be discharged to a display substrate such as an OLED, an application to be wired on a substrate, a liquid containing a compound to be a light emitting element In this case, for example, a liquid containing a conductive metal may be discharged from a droplet discharge head provided in each device. In addition, when the droplet discharge head is used as a dispenser and used for discharging onto a substrate that is a microarray of biomolecules, DNA (Deoxyribo Nucleic Acids: deoxyribonucleic acid), other nucleic acids (for example, Ribo Nucleic Acid: ribonucleic acid, Peptide (Nucleic Acids: peptide nucleic acids, etc.) A liquid containing a probe such as a protein may be discharged. In addition, it can also be used for discharging dyes such as cloth.

2 is an exploded view of a droplet discharge head according to Embodiment 1. FIG. It is sectional drawing of a droplet discharge head. FIG. 6 is a process diagram (part 1) illustrating the production of the nozzle substrate according to the first embodiment. FIG. 6 is a process diagram (part 2) illustrating the production of the nozzle substrate according to the first embodiment. FIG. 6 is a process diagram (part 3) illustrating the production of the nozzle substrate according to the first embodiment. FIG. 6 is a process diagram (part 4) illustrating the production of the nozzle substrate according to the first embodiment. 3 is a diagram illustrating the shape of a nozzle edge portion of a nozzle 31. FIG. It is a figure which shows the contact | adherence state of the protective film 64 and the silicon substrate 51. FIG. It is a figure which shows the manufacturing process of a droplet discharge head. It is an external view of a droplet discharge device using a droplet discharge head. It is a figure showing an example of the main structural means of a droplet discharge apparatus.

Explanation of symbols

  10 electrode substrate, 11 groove portion, 12 electrode portion, 12A individual electrode, 12B lead portion, 12C terminal portion, 13 liquid supply port, 20 cavity substrate, 21 discharge chamber, 22 diaphragm, 23 reservoir, 24 common electrode terminal, 25 insulation Membrane, 26 Electrode outlet, 27 Sealing material, 30 Nozzle substrate, 31 Nozzle, 31A First nozzle, 31A-1 Nozzle outlet, 31B Second nozzle, 31B-1 Nozzle supply port, 32 Orifice, 33 Diaphragm, 34 Recess, 41 Oscillation circuit, 42 wiring, 51 silicon substrate, 51A etched surface, 51B droplet discharge surface, 52, 55, 56 silicon oxide film, 53, 54 photoresist film, 57 liquid repellent layer, 61 support substrate 62 double-sided tape, 63 UV curable adhesive layer, 64 protective film, 64A adhesive layer, 1 silicon substrate, 72 boron-doped layer, 73 silicon oxide film, 100 a printer, 101 a drum, 102 droplet discharge head, 103 paper press roller, 104 a feed screw, 105 belt, 106 motor, 107 print control means 110 print paper.

Claims (12)

In a nozzle substrate made of silicon, in which a nozzle for ejecting liquid is formed through a flat plate,
The nozzle substrate has a discharge port protruding from an end surface of the substrate.   2. The nozzle substrate according to claim 1, wherein the nozzle is formed in a taper shape or a multi-stage shape in which a hole diameter decreases in a direction in which droplets are ejected.   3. The nozzle substrate according to claim 1, wherein a discharge port of the nozzle protrudes from the substrate end face by 0.1 to 1.6 μm. The nozzle substrate according to any one of claims 1 to 3,
A flow path substrate having a flow path for supplying a liquid to the nozzle of the nozzle substrate;
A droplet discharge head comprising: a pressurizing unit for pressurizing the liquid in the flow path substrate.   A droplet discharge apparatus, comprising the droplet discharge head according to claim 4. Performing anisotropic dry etching from one side of the silicon substrate to form a recess to be a nozzle;
Forming a silicon oxide film at least in the recess;
The silicon substrate is fixed with the surface on which the recess is formed facing the support substrate, the silicon substrate is ground and polished from the surface opposite to the surface on which the recess is formed, and a hole is formed through the recess. And a step of forming a nozzle having a truncated cone shape by projecting a portion serving as a discharge port of the nozzle from the end face of the substrate, and a method of manufacturing the nozzle substrate. Performing a water repellent treatment on the silicon substrate on which the nozzle is formed to form a water repellent layer;
Attaching a protective film for protecting the water-repellent layer on the surface on which the discharge ports are formed to the silicon substrate;
The method for manufacturing a nozzle substrate according to claim 6, further comprising a plasma treatment for removing the water repellent layer on the inner wall of the nozzle.   The method of manufacturing a nozzle substrate according to claim 6 or 7, wherein the recesses to be the nozzles are formed so as to have a plurality of steps in which the hole diameter decreases in the liquid discharge direction.   The method for manufacturing a nozzle substrate according to any one of claims 6 to 8, wherein the nozzle is formed by performing polishing by CMP using only the slurry for polishing silicon.   10. The method according to claim 6, wherein, when the polishing is performed, a height and a height at which a portion serving as the discharge port protrudes are adjusted by adjusting a type and / or a weight of the polishing pad. Nozzle substrate manufacturing method. A nozzle substrate manufactured by the method according to claim 6;
A liquid comprising: a step of bonding a flow path for supplying a liquid to the nozzle of the nozzle substrate and a substrate provided with a pressurizing means for pressurizing the liquid to a part of the flow path. A method for manufacturing a droplet discharge head.   A method for manufacturing a droplet discharge device, wherein the droplet discharge device is manufactured by applying the method for manufacturing a droplet discharge head according to claim 11.

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