JP2009012398A - Nozzle substrate manufacturing method - Google Patents

Abstract

There is provided a method for manufacturing a nozzle substrate in which a substrate thickness is not changed, a bottom diameter can be controlled, a desired inclined surface is provided, and a flow path characteristic is optimized.
A step of forming a first protective film on a surface of a silicon substrate, and a second protective film having a material different from that of the first protective film laminated on the first protective film are provided. Forming a second opening hole 43a in the second protective film 43, further forming a first opening hole 42a in the first protective film 42, and the first and second opening holes. A step of forming the vertical hole portion 110 by performing anisotropic dry etching from 42a, 43a, a step of etching the first protective film 42 to expand the diameter of the first opening hole 42a, and the first, second A step of performing isotropic dry etching from the opening holes 42a and 43a to form a tapered hole portion whose cross-sectional area gradually increases toward the first and second opening holes 42a and 43a. .
[Selection] Figure 7

Description

  The present invention relates to a method for manufacturing a nozzle substrate.

  As a droplet discharge head for discharging droplets, for example, an inkjet head mounted on an inkjet recording apparatus is known. Ink jet heads generally include a nozzle substrate in which a plurality of nozzle holes for ejecting ink droplets are formed, and ink such as a discharge chamber and a reservoir that are joined to the nozzle substrate and communicate with the nozzle holes. And a cavity substrate on which a flow path is formed. The drive unit applies pressure to the discharge chamber to discharge ink droplets from selected nozzle holes. As a driving means, there are a method using an electrostatic force, a piezoelectric method using a piezoelectric element, a bubble jet (registered trademark) method using a heating element, and the like.

  In recent years, ink jet heads have been required to have a structure having a plurality of nozzle rows for the purpose of increasing the printing speed and colorization. In addition, the nozzles have a higher density and the number of nozzles per row has increased. The number of actuators in an inkjet head is increasing more and more as the length increases. Against this background, there is a demand for a compact inkjet head having a high nozzle density, a long and numerous nozzle array, and excellent discharge characteristics, and various devices and proposals have been made.

  Some conventional inkjet heads have a nozzle substrate in which a tapered nozzle hole is processed by repeating isotropic dry etching and anisotropic dry etching from one side on a silicon substrate (for example, Patent Documents) 1).

  Furthermore, in a conventional inkjet head, a nozzle substrate in which an inclined nozzle hole portion that is not penetrated by wet etching is formed in a silicon substrate of (100) surface and a vertical nozzle hole portion is penetrated by dry etching from the opposite side is provided. Some have been provided (see, for example, Patent Document 2).

Japanese Patent Laying-Open No. 2006-45656 (page 15, FIG. 16) Japanese Patent Laid-Open No. 10-315461 (pages 4-5, FIG. 2)

  According to the technique described in Patent Document 1, since the undercut of the side wall of the nozzle hole proceeds by isotropic dry etching, it is difficult to control the bottom diameter of the nozzle hole.

  According to the technique described in Patent Document 2, the inclined surface depends on the surface direction of the silicon single crystal substrate, and there is a limit to increasing the nozzle density.

For this reason, it is possible to control the bottom diameter of the nozzle hole and to form the nozzle hole from one side of the substrate so that the inclined surface of the nozzle hole does not depend on the surface direction of the silicon single crystal substrate. It is done.
However, even in this case, there are problems that the thickness of the base material is changed at the time of forming the nozzle hole, the nozzle hole is squeezed, or a stepped portion remains in the nozzle hole.

  The present invention has been made in order to solve the above-described problems. The nozzle hole can be formed without changing the substrate thickness, and the bottom diameter of the nozzle hole can be controlled at this time. An object of the present invention is to provide a method of manufacturing a nozzle substrate having an inclined surface and having optimized flow path characteristics of the nozzle substrate.

  The method for manufacturing a nozzle substrate according to the present invention includes a step of forming a first protective film on a surface of a silicon base material, and a second layer formed on the first protective film and having a material different from that of the first protective film. A step of forming a protective film; a step of forming a second opening hole in the second protective film; and a step of forming the first opening hole in the first protective film; and a step from the first and second opening holes; Performing anisotropic dry etching to form a vertical hole, etching the first protective film to expand the first opening, and isotropic from the first and second openings And performing a dry etching to form a tapered hole having a cross-sectional area gradually increasing toward the first and second opening holes.

Since the surface of the silicon substrate is protected by the first protective film when forming the tapered hole portion of the nozzle hole, the thickness of the silicon substrate does not change during etching. Moreover, the taper-shaped hole part with a desired bottom part diameter and an inclined surface can be formed by controlling the diameter expansion amount of a 1st protective film.
Since the tapered hole formed in this way has a desired inclined surface without depending on the surface direction of the silicon single crystal substrate, the nozzle can be densified. Since the nozzle hole is tapered, there is an effect of preventing pressure loss due to the gradually reducing tube, and an optimum flow path resistance and rectifying action can be obtained. Further, since the vertical hole portion and the tapered hole portion are integrally formed, the meniscus of the droplet can be stably maintained.

  In the method for manufacturing a nozzle substrate according to the present invention, the first protective film is an oxide film, and the second protective film is a nitride film.

  Since the protective film is formed by stacking different types of films, the second protective film is formed when the oxide film as the first protective film is etched to expand the first opening hole to a desired diameter. The nitride film is not etched.

  In the method of manufacturing a nozzle substrate according to the present invention, the oxide film is etched using a buffered hydrofluoric acid aqueous solution.

  Since the protective film is composed of a stack of different types of films, when the oxide film as the first protective film is etched with a buffered hydrofluoric acid solution to expand the first opening hole to a desired diameter, The nitride film as the second protective film is not etched with the buffered hydrofluoric acid aqueous solution.

  In the method for manufacturing a nozzle substrate according to the present invention, the isotropic dry etching includes a first gas for promoting etching and a second gas for adjusting a side etching amount by forming a protective film on the side wall of the vertical hole. This is what is done.

  Etching is promoted by the first gas, and a protective film is formed on the side wall of the vertical hole portion of the nozzle by the second gas to control the side etching amount. A nozzle hole that gradually increases and expands can be formed.

In the method for manufacturing a nozzle substrate according to the present invention, the first gas is SF ₆ and the second gas is O ₂ .

Promote etched by the first gas is SF _6, since by forming a protective on the side wall of the vertical hole portion of the nozzle by a second gas is O ₂ film so as to control the side etching amount, the desired It is possible to form a nozzle hole having an inclined surface and the nozzle cross-sectional area gradually increasing and expanding.

Embodiment 1 FIG.
FIG. 1 is an exploded perspective view showing a section of an ink jet head (an example of a droplet discharge head) according to the first embodiment, and FIG. 2 is a longitudinal sectional view showing a main part in a state where FIG. 1 is assembled. FIG. 3 is an enlarged sectional view showing the vicinity of the nozzle hole of FIG.
As shown in FIGS. 1 and 2, the inkjet head 10 includes a nozzle substrate 1 in which a plurality of nozzle holes 11 are provided at a predetermined pitch, and a cavity in which an ink supply path is provided independently for each nozzle hole 11. The substrate 2 and the electrode substrate 3 on which the individual electrodes 31 are disposed are opposed to the diaphragm 22 of the cavity substrate 2.

  The nozzle substrate 1 is made of a silicon single crystal base material (also simply referred to as a silicon base material). The nozzle substrate 1 is provided with a tapered nozzle hole 11 for ejecting ink droplets, and has a desired inclined surface that is not constrained by the crystal orientation of silicon. As shown in FIG. 3, each nozzle hole 11 has one end opened on the surface 1 a on the front end side in the discharge direction, and the nozzle cross-sectional area from the opening toward the surface 1 b on the rear end side in the discharge direction. Gradually increases, and the other end is opened with the largest diameter on the rear end surface 1b. Then, on the surface 1b on the rear end side in the ejection direction, the bottom diameter of the nozzle hole 11 (the diameter of the opening of the nozzle hole 11 located on the surface 1b on the rear end side) is opened with a desired diameter d.

  The cavity substrate 2 is made of a silicon single crystal base material (also simply referred to as a silicon base material). The silicon substrate is subjected to anisotropic wet etching to form recesses 240 and 250 for forming the discharge chamber 24 and the reservoir 25 of the ink flow path, and a stepped portion 230 for forming the orifice 23, respectively. A plurality of recesses 240 are independently formed at positions corresponding to the nozzle holes 11. Therefore, when the nozzle substrate 1 and the cavity substrate 2 are joined, each recess 240 constitutes the discharge chamber 24, and each recess communicates with the nozzle hole 11 and also with the orifice 23 that is an ink supply port. The bottom wall of the discharge chamber 24 (recess 240) serves as the diaphragm 22.

The other concave portion 250 is for storing liquid ink, and constitutes a reservoir 25 that is a common ink chamber common to the ejection chambers 24. The reservoirs 25 communicate with all the discharge chambers 24 through the orifices 23, respectively. Further, a hole penetrating the electrode substrate 3 described later is provided at the bottom of the reservoir 25, and ink is supplied from an ink cartridge (not shown) through an ink supply hole 34 formed by this hole.
Further, an insulating film 26 made of a SiO ₂ film or the like is formed on the entire surface of the cavity substrate 2 or at least the surface facing the electrode substrate 3. This insulating film 26 prevents dielectric breakdown or short circuit from occurring when the inkjet head 10 is driven.

  The electrode substrate 3 is made from a glass substrate. As the glass substrate, it is preferable to use a borosilicate heat-resistant hard glass having a thermal expansion coefficient close to that of the silicon substrate of the cavity substrate 2. This is because when the electrode substrate 3 and the cavity substrate 2 are anodically bonded, the thermal expansion coefficients of both the substrates 3 and 2 are close, so the stress generated between the electrode substrate 3 and the cavity substrate 2 can be reduced. As a result, the electrode substrate 3 and the cavity substrate 2 can be firmly bonded without causing problems such as peeling.

  On the surface of the electrode substrate 3 facing the cavity substrate 2, a recess 32 is provided at a position facing each diaphragm 22 of the cavity substrate 2. In each recess 32, an individual electrode 31 made of ITO (Indium Tin Oxide) is generally formed. This gap (gap) G formed between the diaphragm 22 and the individual electrode 31 greatly affects the ejection characteristics of the inkjet head. In addition, although the metal of chromium etc. may be used for the material of the individual electrode 31, since ITO is transparent and it is easy to confirm whether it discharged or not, ITO is generally used.

  The individual electrode 31 has a lead part 31a and a terminal part 31b connected to a flexible wiring board (not shown). As shown in FIG. 2, these terminal portions 31b are exposed in an electrode extraction portion 29 in which the end portion of the cavity substrate 2 is opened for wiring.

  The nozzle substrate 1, the cavity substrate 2, and the electrode substrate 3 described above are generally manufactured individually, and are bonded together as shown in FIG. 2 to manufacture the main body of the inkjet head 10. That is, the cavity substrate 2 and the electrode substrate 3 are bonded by, for example, anodic bonding, and the nozzle substrate 1 is bonded to the upper surface of the cavity substrate 2 (the upper surface in FIG. 2) with an adhesive or the like. Furthermore, the open end of the gap G formed between the diaphragm 22 and the individual electrode 31 is sealed with a sealing material 27 made of a resin such as epoxy. Thereby, it is possible to prevent moisture, dust and the like from entering the gap G.

  As shown in FIG. 2, the drive control circuit 4 such as an IC driver is connected to the flexible wiring substrate (not shown) on the terminal portion 31 b of each individual electrode 31 and the common electrode 28 provided on the cavity substrate 2. Z)).

  In the inkjet head 10 configured as described above, when a pulse voltage is applied between the cavity substrate 2 and the individual electrode 31 by the drive control circuit 4, an electrostatic force is generated between the diaphragm 22 and the individual electrode 31. The diaphragm 22 is attracted to the individual electrode 31 side and bent due to the suction action, and the volume of the discharge chamber 24 is increased. As a result, the ink accumulated in the reservoir 25 flows into the discharge chamber 24 through the orifice 23. Next, when the application of voltage to the individual electrode 31 is stopped, the electrostatic attraction force disappears, the diaphragm 22 is restored, and the volume of the discharge chamber 24 contracts rapidly. As a result, the pressure in the discharge chamber 24 increases rapidly, and ink droplets are discharged from the nozzle holes 11 communicating with the discharge chamber 24.

Next, the manufacturing method of the inkjet head 10 is demonstrated using FIGS. 4 is a top view showing the nozzle substrate 1 according to the first embodiment of the present invention, and FIGS. 5 to 11 are cross-sectional views showing the manufacturing process of the nozzle substrate 1 (cross-sectional view taken along line AA in FIG. 4) It is. FIG. 12 and FIG. 13 are cross-sectional views showing the bonding process between the cavity substrate 2 and the electrode substrate 3. Here, after the silicon substrate (cavity substrate) 200 is bonded to the electrode substrate 3 mainly, 2 shows a method of manufacturing 2.
First, a method for manufacturing the nozzle substrate 1 will be described.
In addition, the numerical value described below shows an example, and is not limited to this.

(A) As shown to Fig.5 (a), the silicon base material (nozzle base material) 41 whose thickness is 280 micrometers, for example is prepared.

(B) The silicon substrate 41 is set in a thermal oxidizer, and is subjected to a thermal oxidation treatment under conditions of, for example, an oxidation temperature of 1075 ° C., an oxidation time of 4 hours, and a mixed atmosphere of oxygen and water vapor, as shown in FIG. Then, an oxide film 42 having a thickness of 1 μm, for example, is uniformly formed on the surfaces 41 a and 41 b of the silicon substrate 41.

(C) As shown in FIG. 5C, a nitride film 43 having a thickness of, for example, 1 μm is stacked on the oxide film 42 by plasma CVD.

(D) As shown in FIG. 6D, a resist 44 is coated on the nitride film 43, and a portion 44a corresponding to a portion that becomes the vertical hole portion 110 (see FIG. 7H) is patterned.

(E) As shown in FIG. 6E, the nitride film 43 is opened by the patterned portion 44a by etching with a phosphoric acid aqueous solution at 150 ° C., for example, and a second opening hole 43a is formed. The opening hole 43a may be opened by anisotropic dry etching with CF ₄ .

(F) As shown in FIG. 6 (f), the oxide film is etched by the second opening hole 43 a provided in the nitride film 43 by etching with a buffered hydrofluoric acid aqueous solution (hydrofluoric acid aqueous solution: ammonium fluoride aqueous solution = 1: 6). 42 is opened to form a first opening hole 42a having substantially the same diameter as the second opening hole 43a. The first opening hole 42a may be opened by anisotropic dry etching with CHF ₃ .

(G) As shown in FIG. 6G, the resist 44 is removed by washing with sulfuric acid or the like.

(H) As shown in FIG. 7 (h), the ICP dry etching apparatus is used to vertically (in the drawing, the vertical direction) through the second and first opening holes 43a and 42a of the nitride film 43 and the oxide film 42. Anisotropic dry etching is performed to form a vertical hole 110 having a depth of 70 μm, for example. In this case, for example, C ₄ F ₈ and SF ₆ are used as the etching gas, and these gases are used alternately. Here, C ₄ F ₈ protects the side surface of the hole so that etching does not proceed to the side surface of the hole to be formed, and SF ₆ promotes etching in the vertical direction.

(I) As shown in FIG. 7 (i), the oxide film 42 of the silicon substrate 41 is etched with a buffered hydrofluoric acid aqueous solution to widen the first opening hole 42a in the width direction (left-right direction in the figure). That is, an overhang is formed by the expansion of the oxide film 42.
The width d ₁ of the first opening hole 42a is such that the diameter of the bottom of the nozzle hole 11, that is, the silicon base material 41 of the silicon substrate 41 is formed when the vertical hole 110 is etched to form the tapered nozzle hole 11 as will be described later. This corresponds to the diameter d (see FIG. 3) of the opening of the nozzle hole 11 located on the bonding surface 41a side.

(J) As shown in FIG. 7J, using the oxide film 42 and the nitride film 43 provided with the first and second opening holes 42a and 43a as a mask, the silicon substrate 41 is formed by an ICP dry etching apparatus. The vertical hole 110 is dry etched under isotropic etching conditions. As the etching gas, for example, SF ₆ is used as the first gas, and O ₂ is used as the second gas. In this case, processing is performed in a state where gas is continuously flowed without switching.
The bottom diameter d (upper part in the drawing) of the nozzle hole 11 is regulated by the diameter d _{1 of} the first opening hole 42 a formed in the oxide film 42. Further, the inclined surface of the nozzle hole 11 is controlled by the processing time by etching and the depth of the vertical hole portion 110.
Therefore, the shape of the inclined surface of the vertical hole portion 110 gradually increases in the radial direction with the nozzle cross-sectional area gradually increasing toward the upper portion of the drawing as time passes. On the other hand, the diameter of the upper part (lower part in the figure) of the nozzle hole 11 is maintained as it is.
In the etching described above, the first gas SF ₆ for promoting the etching and the second gas O ₂ for adjusting the side etching amount by forming a protective film on the side wall of the nozzle are used as the second and first opening holes. It introduce | transduces into the vertical hole part 110 from 43a and 42a. By introducing O ₂ as the second gas, an oxide film is formed on the side wall of the nozzle, and the side etching amount can be controlled.

(K) When the ICP dry etching apparatus continues the dry etching to widen the inclined surface and a predetermined time elapses, the tapered nozzle hole 11 having a desired inclined surface is formed as shown in FIG. It is formed. In this case, the bottom diameter d of the formed nozzle hole 11 is the same as the diameter d ₁ of the opening hole 42 a of the oxide film 42.

(L) As shown in FIG. 8L, the nitride film 43 on the surface of the silicon substrate 41 is removed with a phosphoric acid aqueous solution at 150 ° C., for example, and the oxide film 42 is further removed with a buffered hydrofluoric acid aqueous solution.
Thus, a tapered nozzle hole 11 having a desired bottom diameter d and a desired inclined surface is formed.

(M) The silicon substrate 41 is set in a thermal oxidation apparatus, and is subjected to thermal oxidation treatment under conditions of, for example, an oxidation temperature of 1000 ° C. and an oxidation time of 2 hours in an oxygen atmosphere. As described above, an oxide film 46 having a thickness of, for example, 0.1 μm is uniformly formed on the surface of the silicon base 41 including the side and bottom surfaces of the processed nozzle hole 11.

(N) As shown in FIG. 9 (n) (from FIG. 9 (n) to FIG. 9 (q), a diagram obtained by reversing the top and bottom of FIG. 8 (m)) is made of a transparent material such as glass. A double-sided tape 60 is attached to the support substrate 50. Next, the surface of the self-peeling layer 61 of the double-sided tape 60 and the bonding surface 41a of the silicon base material 41 face each other, and the support substrate 50 and the silicon base material 41 are bonded together in a vacuum. In this way, no bubbles remain at the bonding interface, and the bonding is performed cleanly.

(O) Grinding is performed by a back grinder from the discharge surface 41b side of the silicon base material 41, and the silicon base material 41 is thinned until the tip of the nozzle hole 11 is opened as shown in FIG. Further, the tip of the nozzle hole 11 may be opened by polishing the discharge surface 41b with a polisher or a CMP apparatus. Or you may open the front-end | tip of the nozzle hole 11 by dry etching. For example, by dry etching using SF ₆ as an etching gas, the silicon substrate 41 is thinned to the tip of the nozzle hole 11, and the oxide film 46 at the tip 11c of the nozzle hole 11 exposed on the surface is replaced with CF ₄ or CHF ₃ or the like. May be removed by dry etching using an etching gas.

(P) As shown in FIG. 9 (p), an oxide film 47 is formed on the discharge surface 41b of the silicon substrate 41 by a sputtering apparatus so that the thickness becomes, for example, 0.1 μm. Here, the oxide film 47 may be formed at a temperature at which the double-sided tape 60 does not deteriorate (about 200 ° C.) or less, and is not limited to the sputtering method. However, in consideration of ink resistance and the like, it is necessary to form a dense film, and it is preferable to use an apparatus capable of forming a dense film at room temperature, such as an ECR sputtering apparatus.

(Q) As shown in FIG. 9 (q), the ink repellent process is performed on the ejection surface 41b of the silicon base material 41. An ink repellent material containing F atoms is deposited by vapor deposition or dipping to form an ink repellent film 48.

(R) As shown in FIG. 10 (r) (from FIG. 10 (r) to FIG. 10 (u), a view in which the top and bottom of FIG. 9 (q) are reversed is shown), a support tape is provided on the discharge surface 41b. A dicing tape 70 is attached.

(S) As shown in FIG. 10 (s), UV light is irradiated from the support substrate 50 side.

(T) As shown in FIG. 10 (t), the self-peeling layer 61 of the double-sided tape 60 is peeled from the bonding surface 41 a of the silicon substrate 41.

(U) as shown in FIG. 10 (u), by Ar sputtering or 0 ₂ plasma treatment, to remove the ink repellent layer 48 that is excessively formed on the inner wall of the nozzle hole 11 of the silicon substrate 41.

(V) As shown in FIG. 11 (v) (from FIG. 11 (v) to FIG. 11 (w) is a diagram in which the top and bottom of FIG. 10 (u) are reversed), as shown in FIG. The joining surface 41a located on the opposite side of the surface to which the 70 is attached is sucked and fixed by the suction jig 80 communicated with the vacuum pump, and the dicing tape 70 is peeled off in this state.

(W) As shown in FIG. 11 (w), the suction fixing of the suction jig 80 is released and the nozzle substrate 1 is recovered from the silicon base material 41. Since the nozzle substrate outer ring groove is carved in the silicon substrate 1, the nozzle substrate 1 is divided into individual pieces at the stage of picking up from the suction jig 80.

According to the first embodiment, when the nozzle hole 11 is formed by etching, the surface of the nozzle base material 41 is protected by the oxide film 42, so that the thickness of the nozzle base material 41 does not change. Further, the diameter d ₁ of the first opening hole 42a of the oxide film 42 by controlling to a desired size, it is possible to form the nozzle hole 11 having a desired bottom diameter d.
Since the nozzle hole 11 formed in this way is tapered and the inclined surface does not depend on the surface direction of the silicon single crystal substrate, there is an effect of preventing pressure loss due to the gradual reduction tube, and the optimum channel resistance and rectifying action are achieved. Obtainable. Further, since the vertical hole portion 110 and the tapered hole portion constituting the nozzle hole 11 are integrally formed, the ink meniscus can be stably maintained.

Next, a method for manufacturing the cavity substrate 2 and the electrode substrate 3 will be described.
Here, a method of manufacturing the cavity substrate 2 from the silicon substrate 200 after bonding the silicon substrate (cavity substrate) 200 to the electrode substrate 3 will be described with reference to FIGS.

(A) A recess 32 is formed by etching a glass substrate 300 made of borosilicate glass or the like with hydrofluoric acid using a gold / chromium etching mask on a glass substrate 300 having a thickness of, for example, about 1 mm. Note that the recess 32 has a groove shape slightly larger than the shape of the individual electrode 31, and a plurality of the recesses 32 are formed for each individual electrode 31.
Then, an individual electrode 31 made of ITO (Indium Tin Oxide) is formed inside the recess 32 by sputtering, for example.
Thereafter, a hole 34a to be the ink supply hole 34 is formed by a drill or the like, thereby producing the electrode substrate 3 from the glass substrate 300 as shown in FIG.

(B) After both surfaces of the silicon substrate 200 having a thickness of, for example, 525 μm are mirror-polished, as shown in FIG. 12B, the silicon substrate 200 is formed on one surface by plasma CVD (Chemical Vapor Deposition), for example, A silicon oxide film (insulating film) 26 made of TEOS (TetraEthylorthosilicate) having a thickness of 0.1 μm is formed. In addition, before forming the silicon base material 200, a boron dope layer for forming the thickness of the diaphragm 22 with high accuracy may be formed by using an etching stop technique. Etching stop is defined as a state in which bubbles generated from the etching surface are stopped, and in actual wet etching, it is determined that the etching is stopped when the generation of bubbles is stopped.

(C) The silicon substrate 200 and the electrode substrate 3 manufactured as shown in FIG. 12A are heated to, for example, 360 ° C., and the silicon substrate 200 is connected to the anode and the electrode substrate 3 is connected to the cathode. Then, a voltage of about 800 V is applied, and bonding is performed by anodic bonding as shown in FIG.

(D) After anodic bonding of the silicon substrate 200 and the electrode substrate 3, as shown in FIG. 12D, the bonded silicon substrate 200 is etched with an aqueous potassium hydroxide solution or the like, and the silicon substrate 200 is removed. For example, it is thinned to a thickness of 140 μm.

(E) A TEOS film 260 having a thickness of, for example, 1.5 μm is formed by plasma CVD on the entire upper surface of the silicon base material 200 (the surface opposite to the surface to which the electrode substrate 3 is bonded).
Then, the TEOS film 260 is patterned with a resist for forming a concave portion 240 that becomes the discharge chamber 24, a step portion 230 that becomes the orifice 23, and a concave portion 250 that becomes the reservoir 25, and the TEOS film 260 in these portions is removed by etching. To do.
Thereafter, by etching the silicon substrate 200 with an aqueous potassium hydroxide solution or the like, as shown in FIG. 13 (e), a recess 240 serving as the discharge chamber 24, a stepped portion 230 serving as the orifice 23, and a recess 250 serving as the reservoir 25. Form. At this time, the portion that becomes the electrode extraction portion 29 for wiring is also etched and thinned. In the wet etching step, for example, a 35% by weight potassium hydroxide aqueous solution can be used first, and then a 3% by weight potassium hydroxide aqueous solution can be used. Thereby, surface roughness of the diaphragm 22 can be suppressed.

(F) After the etching of the silicon substrate 200 is completed, etching is performed with a hydrofluoric acid aqueous solution, and the TEOS film 260 formed on the upper surface of the silicon substrate 200 is removed as shown in FIG.

(G) As shown in FIG. 13G, a TEOS film (insulating film) 26 is formed on the surface of the silicon substrate 200 on which the recesses 240 and the like serving as the discharge chambers 24 are formed by plasma CVD. Formed at 1 μm.

(H) By RIE (Reactive Ion Etching) or the like, as shown in FIG. Further, laser processing is performed on the hole portion that becomes the ink supply hole 34 of the electrode substrate 3, and the bottom portion of the concave portion 250 that becomes the reservoir 25 of the silicon base material 200 is penetrated to form the ink supply hole 34. Further, the open end of the gap G between the diaphragm 22 and the individual electrode 31 is filled with a sealing material 27 such as epoxy resin and sealed. Further, the common electrode 28 is formed on the end portion of the silicon substrate 200 by sputtering.

As described above, the cavity substrate 2 is manufactured from the silicon base material 200 bonded to the electrode substrate 3.
Finally, the nozzle substrate 1 manufactured as described above (FIGS. 5 to 11) is bonded to the cavity substrate 2 by bonding or the like, whereby the inkjet head 10 shown in FIG. 2 is completed.

  According to the method for manufacturing the inkjet head 10 according to the first embodiment, the cavity substrate 2 is produced from the silicon substrate 200 in a state of being bonded to the electrode substrate 3 produced in advance. 200 is supported, and even if the cavity base material 200 is thinned, it is not cracked or chipped, and handling becomes easy. Therefore, the yield is improved as compared with the case where the cavity substrate 2 is manufactured alone. In addition, since the nozzle substrate 1 is formed of silicon, there is no adhesion position shift due to a difference in thermal expansion coefficient from the cavity substrate generated in the SUS nozzle substrate.

Embodiment 2. FIG.
In the first embodiment, the nozzle hole 11 has a substantially trumpet shape, but in the second embodiment, a vertical portion is further introduced on the front end side in the discharge direction of the substantially trumpet-shaped nozzle hole 11.
That is, as shown in FIG. 14, the nozzle hole 11 has a substantially trumpet-shaped nozzle hole shown in the first embodiment (in the second embodiment, a portion corresponding to this portion is hereinafter referred to as a trumpet portion (second Further, a cylindrical vertical portion (first nozzle hole portion) 11a is provided on the front end side in the discharge direction of the nozzle hole portion 11b). The trumpet portion 11b and the vertical portion 11a constitute the nozzle hole 11 so that the central axes of the trumpet portion 11b and the vertical portion 11a are the same.

The vertical portion 11a of the nozzle hole 11 is further etched vertically by the anisotropic dry etching after the l step of the first embodiment (FIG. 8L). Formed. The etching at this time is anisotropic dry etching, which is performed by alternately using a gas composed of C ₄ F ₈ and SF ₆ . C ₄ F ₈ protects the side surface such that the etching on the side surface does not proceed, SF ₆ facilitates etching of vertical.
Subsequent steps are the same as those after the m step (FIG. 8 (m)) shown in the first embodiment.

  In the second embodiment, as shown in FIG. 14, since the vertical portion 11 a is introduced on the front end side in the ejection direction of the nozzle hole 11 shown in the first embodiment, the ink droplet ejection direction is set to the central axis of the nozzle hole 11. Therefore, the accuracy of the nozzle hole 11 can be further increased.

1 is an exploded perspective view of a droplet discharge head according to Embodiment 1 of the present invention. FIG. 2 is a longitudinal sectional view of a main part in a state where the droplet discharge head of FIG. 1 is assembled. The longitudinal cross-sectional view which expanded the nozzle hole part of FIG. The top view of the nozzle substrate of FIG. Sectional drawing of the manufacturing process which shows the manufacturing method of a nozzle substrate. Sectional drawing of the manufacturing process of the nozzle substrate following FIG. Sectional drawing of the manufacturing process of the nozzle substrate following FIG. Sectional drawing of the manufacturing process of the nozzle substrate following FIG. Sectional drawing of the manufacturing process of the nozzle substrate following FIG. Sectional drawing of the manufacturing process of the nozzle substrate following FIG. FIG. 11 is a cross-sectional view of the nozzle substrate manufacturing process following FIG. 10. Sectional drawing of the manufacturing process which shows the manufacturing method of a cavity substrate and an electrode substrate. Sectional drawing of the manufacturing process following FIG. FIG. 6 is a perspective view showing an ink jet recording apparatus according to Embodiment 2 of the present invention.

Explanation of symbols

  1 nozzle substrate, 2 cavity substrate, 3 electrode substrate, 4 drive control circuit, 10 ink jet head, 11 nozzle hole, 22 diaphragm, 23 orifice, 24 discharge chamber, 25 reservoir, 28 common electrode, 31 individual electrode, 32 recess, 34 Ink supply hole, 41 Silicon substrate, 42 Oxide film, 42a First opening hole, 43 Nitride film, 43a Second opening hole, 44 resist, 110 vertical hole part, 400 Inkjet recording apparatus.

Claims (5)

Forming a first protective film on the surface of the silicon substrate;
Forming a second protective film that is laminated on the first protective film and made of a material different from that of the first protective film;
Forming a second opening hole in the second protective film, and further forming a first opening hole in the first protective film;
Performing anisotropic dry etching from the first and second opening holes to form vertical holes; and
Etching the first protective film to expand the diameter of the first opening hole;
Performing isotropic dry etching from the first and second opening holes to form a tapered hole portion whose cross-sectional area gradually increases toward the first and second opening holes;
A method for manufacturing a nozzle substrate, comprising:   2. The method of manufacturing a nozzle substrate according to claim 1, wherein the first protective film is an oxide film, and the second protective film is a nitride film.   3. The method of manufacturing a nozzle substrate according to claim 2, wherein the etching of the oxide film is performed using a buffered hydrofluoric acid aqueous solution.   The isotropic dry etching is performed by using a first gas for promoting etching and a second gas for adjusting a side etching amount by forming a protective film on a side wall of the vertical hole. Item 4. A method for producing a nozzle substrate according to any one of Items 1 to 3. It said first gas is SF _6, a manufacturing method of a nozzle plate according to claim 4, wherein said second gas is O _2.

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