JP2007045110A - Manufacturing method for liquid droplet discharging head, and manufacturing method for liquid droplet discharging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a liquid droplet discharging head which can increase the width precision of a discharging chamber, and to provide a manufacturing method for a liquid droplet discharging device in a process for forming a cavity section for a discharging chamber or the like on a silicon board after anode-bonding the silicon board and an electrode glass board. <P>SOLUTION: After bonding the silicon board 200 to the electrode glass board 301 on which an individual electrode 31 has been formed in advance, the silicon board is formed into a sheet. Then, the patterning of a TEOS etching mask 204 is performed to form a recess section becoming the discharging chamber by etching in this manufacturing method for this liquid droplet discharging head. In the manufacturing method, the patterning of the etching mask is performed by dry etching, and the silicone etching is performed by drying etching first, and is performed by wet etching in the end. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a droplet discharge head that discharges a liquid material and a method for manufacturing a droplet discharge device. Here, the “liquid material” refers to a material having a viscosity that can be discharged from a nozzle, regardless of whether the material is aqueous or oily. It is sufficient if it has fluidity (viscosity) that can be discharged from the nozzle, and even if a solid substance is mixed, it may be a fluid as a whole.

  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 plate in which a plurality of nozzle holes for discharging ink droplets are formed, and an ink in a discharge chamber, a reservoir, or the like that is joined to the nozzle plate and communicates with the nozzle holes. And a cavity plate in which a flow path is formed, and an ink droplet is ejected from a selected nozzle hole by applying pressure to the ejection chamber by a driving unit. 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, an electrostatic drive type inkjet head has been required to be low in cost, high in density, and stable in ejection characteristics. As a process to realize this, after joining the silicon substrate for forming the cavity part of the ink flow path and the electrode glass substrate on which the electrode pattern is formed, the silicon substrate is thinned and then wet etching is performed on the silicon substrate. A process for forming a cavity portion serving as a discharge chamber, a reservoir, or the like by applying is proposed (see, for example, Patent Document 1).
There is also a method of forming a discharge chamber by performing two-stage etching using a high concentration potassium hydroxide aqueous solution and a low concentration potassium hydroxide aqueous solution on a silicon substrate having a boron-doped layer (for example, Patent Document 2). reference).

JP 2004-82572 A (page 6-7, FIG. 2, FIG. 5) Japanese Patent Laid-Open No. 9-234873 (page 4-5, FIG. 5)

In order to achieve high density, stable discharge characteristics, and low cost in an electrostatically driven inkjet head, the cavity plate has a dimensional accuracy in the discharge chamber, especially in the width direction (nozzle pitch direction). Must be ensured with high accuracy.
However, in each of the above prior arts, the etching mask of the silicon substrate is patterned by wet etching to form the discharge chamber, so that the etching mask cannot be cut vertically, and the amount of side etching is increased. Therefore, the width accuracy of the discharge chamber may be reduced and the gap of the interval wall may be lost.

  Accordingly, the present invention provides a droplet discharge head that can improve the width accuracy of a discharge chamber in a process of forming a cavity such as a discharge chamber on the silicon substrate after anodically bonding a silicon substrate and an electrode glass substrate. It is an object to provide a method and a manufacturing method of a droplet discharge device.

  In order to solve the above-described problems, a method for manufacturing a droplet discharge head according to the present invention includes bonding a silicon substrate to an electrode glass substrate on which individual electrodes are formed in advance, then thinning the silicon substrate, and then patterning an etching mask. Then, in the method of manufacturing a droplet discharge head in which the recess that becomes the discharge chamber is formed by etching, the etching mask is patterned by dry etching.

  According to the present invention, the silicon substrate after being bonded to the electrode glass substrate is thinned, and the etching mask formed on the silicon substrate is patterned by dry etching. Since it does not occur, the dimensional accuracy of the pattern can be improved. For this reason, since the concave portion that becomes the discharge chamber can be etched vertically, the width accuracy of the discharge chamber can be improved.

Further, in the method for manufacturing a droplet discharge head according to the present invention, the silicon etching of the recess that becomes the discharge chamber is performed first by dry etching and finally by wet etching.
By first performing silicon etching of the concave portion serving as the discharge chamber by dry etching, the side surface of the concave portion can be dug down vertically. Finally, by performing wet etching, the bottom surface of the recess, that is, the surface roughness of the diaphragm can be suppressed. Therefore, in combination with the improvement in the pattern dimension accuracy described above, it becomes possible to improve the width accuracy of the discharge chamber and reduce the surface roughness of the diaphragm, increase the density of the droplet discharge head, stabilize the discharge characteristics, and Cost reduction can be achieved.

In the method of manufacturing a droplet discharge head according to the present invention, dry etching is performed until the thickness of the bottom of the concave portion serving as the discharge chamber becomes a value close to the target value, and then the wet etching is switched to the target value. Wet etching is performed until
Thereby, the improvement effect of the width accuracy of a discharge chamber and the reduction effect of the surface roughness of a diaphragm can be improved further.

  Further, as the dry etching of the concave portion serving as the discharge chamber, anisotropic dry etching by ICP (Inductively Coupled Plasma) discharge is suitable.

Furthermore, in this case, it is preferable to use SF ₆ and CF ₄ or C ₄ F ₈ as the etching gas.
SF ₆ promotes the etching of the concave portion in the vertical direction, and CF ₄ or C ₄ F ₈ functions to protect the side surface so that the etching in the side surface direction of the concave portion does not proceed. Therefore, by alternately and repeatedly using these etching gases, the side surfaces of the recesses serving as discharge chambers can be etched vertically.

Moreover, it is preferable to use a low-concentration potassium hydroxide aqueous solution in the wet etching of the concave portion serving as the discharge chamber.
Thereby, the surface roughness of the diaphragm on the bottom surface of the recess can be reduced, and the thickness of the diaphragm can be accurately processed to a target value.

  The etching mask is preferably patterned by RIE (Reactive Ion Etching) dry etching.

Further, as the silicon substrate, it is suitable to use a silicon single crystal substrate having a (110) plane orientation in which a boron-doped layer having a required thickness is formed.
As a result, the side surface of the discharge chamber can be etched vertically, and the etching stop can be sufficiently effective on the surface of the boron doped layer, so that the thickness of the diaphragm can be controlled with high accuracy.

Further, in the method for manufacturing a droplet discharge head according to the present invention, a recess serving as a reservoir is further formed in the silicon substrate by wet etching, and the thickness of the bottom of the reservoir is made thicker than the thickness of the bottom of the discharge chamber. It is preferable to do.
Since the reservoir has a larger bottom area than the discharge chamber, the bottom may be cracked if the thickness of the bottom is the same. Therefore, by forming the reservoir at the bottom portion thicker than the discharge chamber bottom portion (that is, the diaphragm), it is possible to prevent cracking and prevent the etching solution from entering the gap between the electrodes.

In the method for manufacturing a droplet discharge head of the present invention, an equipotential contact that is short-circuited with all of the individual electrodes is formed on the electrode glass substrate, and the equipotential contact is anodic bonded to the silicon substrate. It is formed in contact with the silicon substrate.
Thereby, at the time of anodic bonding, since the silicon substrate and the electrode glass substrate are equipotential, no short circuit occurs between the two substrates.

In the method for manufacturing a droplet discharge head according to the present invention, the electrode glass substrate is provided with an air opening hole communicating with the recess where the individual electrode is formed and the recess where the equipotential contact is formed, The air opening hole is opened until anodic bonding of the electrode glass substrate and the silicon substrate, and is closed after anodic bonding.
Since the air opening hole is open until anodic bonding, the gas generated during anodic bonding can be discharged to the outside, so the gap between the electrodes does not become a positive pressure and the diaphragm is prevented from being damaged. be able to. On the other hand, since it is closed after anodic bonding, the chemical solution can be prevented from entering the gap between the electrodes.

A method for manufacturing a droplet discharge device according to the present invention is a method for manufacturing a droplet discharge device using any one of the above-described methods for manufacturing a droplet discharge head.
According to the present invention, a liquid droplet discharge head having stable discharge characteristics, high density, and low cost can be obtained. Therefore, a liquid droplet discharge device having the same effect can be provided.

  Hereinafter, embodiments of a droplet discharge head manufactured by the manufacturing method of the present invention will be described with reference to the drawings. Here, as an example of the droplet discharge head, a face discharge type electrostatic drive type inkjet head will be described with reference to FIGS. Note that the present invention is not limited to the structure and shape shown in the following drawings, and can be similarly applied to an edge discharge type liquid droplet discharge head.

  FIG. 1 is an exploded perspective view showing an exploded schematic configuration of the ink jet head according to the present embodiment, and a part thereof is shown in cross section. FIG. 2 is a cross-sectional view of the inkjet head showing a schematic configuration of the right half of FIG. FIG. 3 is a top view of the inkjet head of FIG. 1 and 2 are shown upside down from a state in which they are normally used.

  As shown in FIGS. 1 and 2, the inkjet head (an example of a droplet discharge head) 10 according to this embodiment includes a nozzle plate 1 in which a plurality of nozzle holes 11 are provided at a predetermined pitch, and each nozzle hole 11. In contrast, the cavity plate 2 provided with the ink supply path independently and the electrode substrate 3 provided with the individual electrodes 31 facing the vibration plate 22 of the cavity plate 2 are bonded together. The manufacturing method will be described in detail later.

  The nozzle plate 1 is made of, for example, a silicon single crystal substrate (hereinafter also simply referred to as a silicon substrate) having a thickness of 180 μm. In the nozzle plate 1, a recess 12 is formed in a region where a plurality of nozzle holes 11 are provided, and a nozzle hole 11 for ejecting ink droplets is opened on the bottom surface of the recess 12. That is, the flow path resistance of each nozzle hole 11 is adjusted by thinning the length of the nozzle portion (substrate thickness) by the recess 12. This ensures uniform ejection performance and prevents other objects such as recording paper from coming into direct contact with the ejection surface (bottom surface of the recess 12), so that the recording paper is soiled or the tip of the nozzle hole 11 is damaged. Can be prevented.

  The nozzle holes 11 for ejecting ink droplets are composed of, for example, two-stage cylindrical nozzle holes having different diameters, that is, an ejection port portion 11a having a smaller diameter and an introduction port portion 11b having a larger diameter. It is configured. The injection port portion 11a and the introduction port portion 11b are provided perpendicular to and coaxially with respect to the substrate surface. The injection port portion 11a has a tip opening on the surface of the nozzle plate 1, and the introduction port portion 11b is the nozzle plate 1. Are opened on the back surface (the surface on the bonding side to be bonded to the cavity plate 2).

  As described above, the nozzle hole 11 is configured in two stages from the ejection port portion 11a and the inlet port portion 11b having a larger diameter, thereby aligning the ink droplet ejection direction with the central axis direction of the nozzle hole 11. And stable ink ejection characteristics can be exhibited. That is, there is no variation in the flying direction of ink droplets, there is no scattering of ink droplets, and variations in the ejection amount of ink droplets can be suppressed. In addition, the nozzle density can be increased.

  Further, in FIG. 2 of the nozzle plate 1, an orifice (narrow groove) 13 that forms a part of the ink flow path is provided on the lower surface (the surface on the joint side with the cavity plate 2). Further, a diaphragm portion 14 that is thinned by a concave portion is provided at a position corresponding to a reservoir 23 of the cavity plate 2 described later. The diaphragm portion 14 is provided to suppress pressure fluctuation in the reservoir 23.

  The cavity plate 2 is made of, for example, a (110) plane-oriented silicon single crystal substrate having a thickness of about 50 μm (this substrate is also simply referred to as a silicon substrate hereinafter). This silicon substrate has a boron-doped layer, and by performing anisotropic dry etching and anisotropic wet etching on the silicon substrate, the recesses 24 and 25 for forming the discharge chamber 21 and the reservoir 23 of the ink flow path are high. Formed with precision. A plurality of recesses 24 are independently formed at positions corresponding to the nozzle holes 11. Therefore, as shown in FIG. 2, when the nozzle plate 1 and the cavity plate 2 are joined, each recess 24 constitutes a discharge chamber 21 and communicates with each nozzle hole 11 and the orifice 13 serving as an ink supply port. Both communicate with each other. And the diaphragm 22 with high thickness precision is comprised by the thickness of the boron dope layer which comprises the bottom wall of the discharge chamber 21 (recessed part 24).

  The other recess 25 is for storing liquid material ink, and constitutes a common reservoir (common ink chamber) 23 for each discharge chamber 21. The reservoirs 23 (recesses 25) communicate with all the discharge chambers 21 through the orifices 13, respectively. Further, a hole penetrating the electrode substrate 3 described later is provided in the bottom of the reservoir 23, and ink is supplied from an ink cartridge (not shown) through an ink supply port 35 of the hole.

  Further, as described above, the (110) orientation silicon single crystal substrate is used for the cavity plate 2 by performing anisotropic etching and anisotropic wet etching on the silicon substrate in two stages. This is because the side surfaces of the recesses and grooves can be etched perpendicularly to the upper or lower surface of the silicon substrate and with high dimensional accuracy, thereby increasing the density of the inkjet head, stabilizing the ejection characteristics, and reducing the cost. Can be achieved.

An insulating film 26 made of a TEOS (Tetraethylorthosilicate Tetraethoxysilane) film is formed by plasma CVD (Chemical Vapor Deposition) on the lower surface of the cavity plate 2, that is, the surface facing the electrode substrate 3 to a thickness of 0.1 μm. It is formed with. This insulating film 26 is provided for the purpose of preventing dielectric breakdown and short circuit when the ink jet head is driven.
On the upper surface of the cavity plate 2, that is, the surface facing the nozzle plate 1 (including the inner surfaces of the discharge chamber 21 and the reservoir 23), an SiO ₂ film (including a TEOS film) serving as the ink protection film 27 is formed by plasma CVD or sputtering. Has been. This ink protective film 27 is provided in order to prevent corrosion of the flow path by ink.

  The electrode substrate 3 is made from a glass substrate having a thickness of about 1 mm, for example. Among them, it is suitable to use a borosilicate heat-resistant hard glass having a thermal expansion coefficient close to that of the silicon substrate of the cavity plate 2. This is because when the electrode substrate 3 and the cavity plate 2 are anodically bonded, the thermal expansion coefficients of the two substrates are close to each other, so that the stress generated between the electrode substrate 3 and the cavity plate 2 can be reduced, and as a result, peeling, etc. This is because the electrode substrate 3 and the cavity plate 2 can be firmly bonded without causing the above problem.

The electrode substrate 3 is provided with a recess 32 at a position on the surface of the cavity plate 2 facing each diaphragm 22. The recess 32 is formed to a depth of about 0.2 μm by etching. In general, individual electrodes 31 made of ITO (Indium Tin Oxide) are formed on the bottom surface of each recess 32 by sputtering, for example, with a thickness of 0.1 μm. At this time, an ITO pattern to be the equipotential contact 33 is also formed at the same time.
Therefore, the gap (gap) formed between the diaphragm 22 and the individual electrode 31 is determined by the depth of the recess 32 and the thickness of the insulating film 26 covering the individual electrode 31 and the diaphragm 22. This gap (interelectrode gap) greatly affects the ejection characteristics of the inkjet head. Here, the material of the individual electrode 31 and the equipotential contact 33 is not limited to ITO, and a metal such as chrome may be used. However, as described later, the equipotential contact 33 can be formed simultaneously, and the ITO is transparent. Therefore, ITO is generally used because it is easy to confirm whether or not the discharge has occurred.

  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 FIGS. 1 to 3, these terminal portions 31 b are exposed in an electrode extraction portion 29 in which the end portion of the cavity plate 2 is opened for wiring.

  As described above, the nozzle plate 1, the cavity plate 2, and the electrode substrate 3 are bonded together as shown in FIG. Furthermore, the open end portion of the interelectrode gap formed between the diaphragm 22 and the individual electrode 31 is sealed with a sealing material 37 made of resin such as epoxy. Thereby, moisture and dust can be prevented from entering the gap between the electrodes, and the reliability of the inkjet head 10 can be kept high.

Finally, as shown in a simplified manner in FIGS. 2 and 3, a drive control circuit 4 such as an IC driver is connected to the terminal portion 31 b of each individual electrode 31 and the common electrode 28 provided on the cavity plate 2. They are connected via a wiring board (not shown).
Thus, the ink jet head 10 is completed.

Next, the operation of the inkjet head 10 configured as described above will be described.
The drive control circuit 4 is an oscillation circuit that controls the supply and stop of charges to the individual electrodes 31. This oscillation circuit oscillates at, for example, 24 kHz, and supplies electric charges by applying pulse potentials of, for example, 0 V and 30 V to the individual electrodes 31. When the oscillation circuit is driven and charges are supplied to the individual electrode 31 to be positively charged, the diaphragm 22 is negatively charged and an electrostatic force (Coulomb force) is generated between the individual electrode 31 and the diaphragm 22. Therefore, the diaphragm 22 is attracted to the individual electrode 31 by this electrostatic force and bends (displaces). As a result, the volume of the discharge chamber 21 increases. When the supply of electric charges to the individual electrode 31 is stopped, the diaphragm 22 returns to its original state due to its elastic force, and at this time, the volume of the discharge chamber 21 decreases rapidly. Part of the ink is ejected from the nozzle hole 11 as an ink droplet. Next, when the vibration plate 22 is similarly displaced, ink is supplied from the reservoir 23 to the discharge chamber 21 through the orifice 13.

As described above, the inkjet head 10 of the present embodiment has a cylindrical injection port portion 11a in which the nozzle holes 11 are perpendicular to the surface (discharge surface) of the nozzle plate 1, and is coaxial with the injection port portion 11a. Since the inlet port portion 11b is provided and has a larger diameter than the jet port portion 11a, the ink droplets can be discharged straight in the direction of the central axis of the nozzle hole 11 and have extremely stable discharge characteristics.
Furthermore, since the cross-sectional shape of the inlet port portion 11b can be formed in a circular shape, a quadrangular shape, or the like, the density of the inkjet head 10 can be increased.

  In addition, the cross-sectional shape of the injection port portion 11a and the introduction port portion 11b of the nozzle hole 11 is not particularly limited, and is formed in a square shape or a circular shape. However, a circular shape is preferable because it is advantageous in terms of discharge characteristics and workability.

Next, a method for manufacturing the inkjet head 10 will be described with reference to FIGS. The physical quantities such as specific numerical values shown below are merely examples, and are not limited thereto.
FIG. 4 is a top view of a part of the electrode glass substrate 301 as viewed from above, and represents the electrode glass substrate of a certain head chip (inkjet head). FIG. 5 is an enlarged cross-sectional view of the equipotential contact 33 portion of the electrode glass substrate 301. 6 and 7 are cross-sectional views of the manufacturing process showing the method for manufacturing the ink jet head 10. 6A to 6D show a cross section of the equipotential contact 33 portion of the electrode glass substrate 301, and FIG. 6E and after and FIG. 7 show cross sections of the individual electrode 31 portion of the electrode glass substrate 301. Show.

First, as shown in FIG. 4 and FIG. 6A, an electrode glass substrate 301 that is the basis of the electrode substrate 3 having the individual electrodes 31 and the equipotential contacts 33 is manufactured. In this step, for example, a borosilicate heat-resistant hard glass substrate having a thickness of about 1 mm is used as the glass substrate 300, and the glass substrate 300 is etched with hydrofluoric acid using, for example, a gold / chromium etching mask. Thus, a concave portion 32 having a depth of 0.2 μm is formed in accordance with the shape pattern of the electrode portion (referring to an electrode portion including the individual electrode 31, the lead portion 31a, and the terminal portion 31b). As shown in FIG. 4, the portion that becomes the equipotential contact 33 is left without being etched so as to form a contact portion on the surface of the glass substrate 300. Therefore, the equipotential contact 33 protrudes on the surface of the glass substrate 300 with a thickness of 0.1 μm. Here, the shape of the equipotential contact 33 is not limited as long as the electrode portion and the silicon substrate can be brought into contact with each other to be equipotential. Note that all the individual electrode recesses 32 and the equipotential contact recesses 34 are connected at one end and communicated with an air opening hole 38 penetrating the glass substrate 300.
Then, after the formation of the recesses 32 and 34, an ITO film serving as an electrode portion with a thickness of 0.1 μm is formed on the surface of the glass substrate 300 by a sputtering method, for example, and individual electrodes are formed on the bottom surface of the recess 32 by a photolithography method. 31 and an equipotential contact 33 is formed on the surface of the glass substrate 300 by extending from the recess 34. All the individual electrodes 31 and the equipotential contacts 33 are formed to be short-circuited by the connection portion 39.
Finally, the ink supply port 35 and the air opening hole 38 are formed from the surface side of the glass substrate 300 by cutting using, for example, a sandblast method or a drill.
Thus, the electrode glass substrate 301 is manufactured.

Next, as shown in FIG. 6B, one surface of a single crystal silicon substrate having a low oxygen concentration with a plane orientation of (110) is mirror-polished to produce a silicon substrate 200 having a thickness of 220 μm.
Thereafter, the surface on which the boron doped layer 201 to be the vibration plate 22 is formed on the silicon substrate 200 is set on a quartz boat so as to face a solid diffusion source mainly composed of B ₂ O ₃ . Then, the quartz boat is set in a vertical furnace, the inside of the furnace is put into a nitrogen atmosphere, the temperature is raised to 1050 ° C., the temperature is maintained for 7 hours, and boron is diffused into the silicon substrate 200 to obtain a thickness of 0 A boron-doped layer 201 having a thickness of 8 μm is formed. In the boron doping process, it is preferable that the silicon substrate 200 is charged at 800 ° C. and the silicon substrate is taken out at 800 ° C. Accordingly, it is possible to quickly pass through a region (600 ° C. to 800 ° C.) where the growth rate of oxygen defects is high, so that the generation of oxygen defects can be suppressed. Further, although a boron compound is formed on the surface of the boron doped layer 201 (not shown), 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 can be chemically changed to B ₂ O ₃ + SiO ₂ . B ₂ O ₃ + SiO ₂ is removed by etching with a hydrofluoric acid aqueous solution in a state where it is chemically changed to B ₂ O ₃ + SiO ₂ .
Then, a TEOS insulating film 26 having a thickness of 0.1 μm is formed on the surface on which the boron doped layer 201 is formed by plasma CVD (Chemical Vapor Deposition). The TEOS insulating film 26 is formed, for example, at a 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 of 100 cm ³ / min (100 sccm), and an oxygen flow rate of 1000 cm ³ / min (1000 sccm). )
Next, a resist is applied to the surface of the formed TEOS insulating film 26, resist patterning is performed to open the window portion 26a to which the equipotential contact 33 contacts at the time of anodic bonding, and etching is performed with a hydrofluoric acid aqueous solution to etch the TEOS insulating film 26. Is patterned. Then, the resist is peeled off.

Next, as shown in FIG. 6C, after heating the silicon substrate 200 and the electrode glass substrate 301 to 360 ° C., the negative electrode is connected to the electrode glass substrate 301 and the positive electrode is connected to the silicon substrate 200, and a voltage of 800 V is applied. Applied and anodic bonded. At this time, as shown in FIGS. 4 and 5, the equipotential contact 33 short-circuited to all the individual electrodes 31 comes into contact with the boron doped layer 201 of the silicon substrate 200 through the window portion 26 a of the TEOS insulating film 26. Therefore, it is possible to prevent a discharge short circuit between the silicon substrate 200 and the individual electrode 31 due to a strong electric field during anodic bonding.
In addition, during anodic bonding, there are cases where glass is electrochemically decomposed at the interface between the silicon substrate and the electrode glass substrate to generate oxygen. In some cases, gas adsorbed on the substrate surface is generated by heating. Since these gases are discharged to the outside from the atmosphere opening hole 38, the inside of the gap between the electrodes does not become a positive pressure. Accordingly, it is possible to prevent a situation in which the diaphragm is cracked when a recess serving as a discharge chamber is formed by etching as will be described later.

Next, as shown in FIG. 6D, after anodic bonding, the surface of the silicon substrate 200 is ground until the thickness of the silicon substrate 200 becomes about 60 μm. Thereafter, in order to remove the work-affected layer, the silicon substrate 200 is etched by about 10 μm with a potassium hydroxide solution having a concentration of 32 wt%. As a result, the thickness of the silicon substrate 200 is about 50 μm.
In this grinding step and work-affected layer removal step, the air opening hole 38 is closed using, for example, a single-sided protective jig or tape so that the etching solution does not enter the gap between the electrodes from the air opening hole 38. The inside of the gap between electrodes is protected. Since the ink supply port 35 is closed at the joint surface between the silicon substrate 200 and the glass substrate 300 at this stage, the etching liquid does not enter the interelectrode gap through the ink supply port 35.

Next, as shown in FIG. 6E, a TEOS etching mask 204 with a thickness of 0.5 μm is formed on the entire etching surface of the silicon substrate 200 by using plasma CVD. The TEOS etching mask 204 is formed, for example, at a temperature of 360 ° C., a high frequency output of 700 W, a pressure of 33.3 Pa (0.25 Torr), a gas flow rate of TEOS flow rate 100 cm ³ / min (100 sccm), and an oxygen flow rate of 1000 cm ³ / min ( 1000 sccm).

Next, as shown in FIG. 6 (f), for example, an epoxy adhesive is poured into the atmosphere opening hole 38 to seal the atmosphere opening hole 38. As a result, the gap between the electrodes is hermetically sealed, and liquid and gas do not enter from the air opening hole 38 in the subsequent processes.
Next, resist patterning is performed to etch the TEOS etching mask 204 in the portion 21a corresponding to the discharge chamber. Then, using a RIE (Reactive Ion Etching) plasma etching apparatus, etching is performed until the TEOS etching mask 204 disappears, and the TEOS etching mask 204 is patterned. The etching conditions are, for example, a high frequency output of 250 W, a pressure of 1.3 Pa (0.01 Torr), and a CHF ₃ gas flow rate of 5 cm ³ / min (5 sccm). After etching, the resist is peeled off.
Thus, by patterning the TEOS etching mask 204 by dry etching, the portion 21a corresponding to the discharge chamber can be opened vertically, and the pattern dimension accuracy can be improved.

Next, as shown in FIG. 6G, resist patterning is performed in order to etch the TEOS etching mask 204 of the portions 23a and 29a corresponding to the reservoir portion and the electrode extraction portion. Then, using a RIE plasma etching apparatus, the TEOS etching mask 204 is etched by 0.2 μm, and the TEOS etching mask 204 is patterned. The etching conditions are, for example, a high frequency output of 250 W, a pressure of 1.3 Pa (0.01 Torr), and a CHF ₃ gas flow rate of 5 cm ³ / min (5 sccm). As a result, the thickness of the TEOS etching mask 204 remaining in the reservoir portion and the electrode extraction portion becomes 0.3 μm. This remaining thickness needs to be changed depending on the desired depth of the reservoir portion. After etching, the resist is peeled off.

Next, as shown in FIG. 6 (h), using an ICP (Inductively Coupled Plasma) dry etching apparatus, the thickness of the bottom of the recess 24 serving as the discharge chamber 21 is a value close to a target value (for example, 0.80 μm). The silicon substrate 200 is subjected to anisotropic dry etching until the thickness becomes (for example, about 5 μm). The etching conditions are, for example, an etching process with an SF ₆ flow rate of 300 cm ³ / min (300 sccm), an etching time of 3 seconds, a chamber pressure of 8 Pa, a coil power of 2200 W, a platen power of 55 W, a platen temperature of 30 ° C., and a deposition process of CF ₄ flow rate. 200 cm ³ / min (200 sccm), etching time 2.5 seconds, chamber pressure 2.7 Pa, coil power 1800 W, platen temperature 30 ° C. This etching process and deposition process are combined into one cycle, and about 30 cycles are performed. Here, SF ₆ is used to promote the etching of the recess 24 in the vertical direction, and CF ₄ is used to protect the side surface of the recess 24 so that the etching does not proceed in the side direction of the recess 24. In addition to CF ₄ , C ₄ F ₈ can also be used.

Next, as shown in FIG. 7I, in order to remove the TEOS etching mask 204 in the reservoir portion and the electrode extraction portion, the substrate already bonded to the hydrofluoric acid aqueous solution (after the bonding of the silicon substrate 200 and the electrode glass substrate 301). Immerse and remove the substrate.
Next, as shown in FIG. 7J, the bonded substrate is immersed in a 3 wt% potassium hydroxide aqueous solution, and anisotropic wet etching is performed until the etching stop due to the etching rate reduction in the boron doped layer 201 is sufficiently effective. to continue. By performing two-stage etching that combines the anisotropic dry etching and the anisotropic wet etching, the dimensional accuracy of the width of the discharge chamber 21 is improved, and the surface roughness of the diaphragm 22 is suppressed. The thickness accuracy can be 0.80 ± 0.05 μm or less, and the ejection performance of the inkjet head can be stabilized. Further, the etching time is controlled so that the thickness of the reservoir 23 and the electrode extraction part 29 is about 20 μm.
This is because the reservoir part and electrode extraction part have a larger area than the diaphragm part, so that when the bottom part is thinned by silicon etching, a thin film with the same thickness as the diaphragm remains as before. This is because such a structure has very low rigidity and may be broken by mechanical vibrations or a force that pushes up a foreign substance sandwiched in the gap between the electrodes. Therefore, if a structure having a thickness of about 20 μm is provided as in the present embodiment, it will not break in the thinning process, and the chemical solution can be prevented from entering the gap between the electrodes.

Next, as shown in FIG. 7K, after the silicon etching is completed, the bonded substrate is immersed in a hydrofluoric acid aqueous solution, and the TEOS etching mask 204 on the silicon substrate surface is peeled off.
Next, as shown in FIG. 7 (l), in order to remove the silicon thin film remaining on the electrode extraction portion 29, a silicon mask is attached to the surface of the silicon substrate, RF power 200W, pressure 40Pa (0.3 Torr), RIE dry etching is performed for 1 hour under the condition of a CF ₄ flow rate of 30 cm ³ / min (30 sccm), and plasma is applied only to the electrode extraction portion to open. At this time, the gap between the electrodes is opened to the atmosphere.
The silicon mask is mounted by pin alignment in which pins are passed through the bonded substrate and the silicon mask.

Next, as shown in FIG. 7 (m), a silicon mask having an opening only in a portion (discharge chamber and reservoir portion) where the TEOS ink protective film 27 is to be formed is attached to the surface of the silicon substrate. Then, a TEOS ink protective film 27 is formed to a thickness of 0.1 μm on the upper surface of the silicon substrate by plasma CVD. The TEOS ink protective film 27 is formed, for example, at a 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 of 100 cm ³ / min (100 sccm), and an oxygen flow rate of 1000 cm ³ / min ( 1000 sccm). The TEOS ink protective film may be a SiO ₂ film formed by sputtering other than plasma CVD.
The silicon mask is mounted by pin alignment in which pins are passed through the bonded substrate and the silicon mask.
The ink protective film 27 has the effect of preventing the corrosion of the flow path due to the ink, and also has the effect of reducing the warpage of the diaphragm portion because the stress of the insulating film 26 and the stress of the ink protective film 27 are offset.
Further, a common electrode 28 made of a metal such as Al is formed on the edge of the surface of the silicon substrate by a sputtering method using a metal mask or the like.
Further, the ink supply port 35 is formed by performing laser processing from the hole portion serving as the ink supply port 35 of the electrode glass substrate 301 and penetrating the bottom of the reservoir portion of the silicon substrate 200.

Next, as shown in FIG. 7 (n), epoxy resin is poured along the open end of the interelectrode gap to seal the interelectrode gap. As a result, the gap between the electrodes is again sealed. Further, the grooves (concave portions 32, 34) communicating with the sealed atmosphere opening hole 38, the individual electrode 31, and the equipotential contact 33 are individually insulated and separated by the sealing material 37 (see FIGS. 3 and 4).
As described above, each part of the cavity plate 2 is manufactured. Then, as shown in FIG. 7 (o), the nozzle plate 1 prepared in advance is bonded to the upper surface of the cavity plate 2 with an epoxy adhesive.

  Finally, as shown in FIG. 7 (p) and FIG. 4, if the dicing is performed along the dicing line 50 and cut into individual heads, the main body of the ink jet head 10 shown in FIG. 2 is obtained. At this time, the individual electrode 31 and the equipotential contact 33 that are short-circuited at the time of anodic bonding are individually divided. Further, the sealed atmosphere opening hole 38 and the groove on the glass substrate communicating therewith are also cut and separated from the completed inkjet head 10.

FIG. 8 is an explanatory diagram comparing the etching mask patterning method for the silicon substrate 200 between the conventional method and the method of the present invention.
In the conventional method, after forming a resist pattern, a TEOS etching mask is etched using a hydrofluoric acid aqueous solution to perform patterning. In this case, since the etching is isotropic, the TEOS etching mask under the resist is also slightly etched and a pattern is formed. If silicon is etched in this state, side etching increases or pattern dimensional accuracy decreases.
On the other hand, in the method of the present invention, since the TEOS etching mask is patterned by dry etching using an RIE plasma etching apparatus, the TEOS etching mask can be patterned vertically. For this reason, pattern dimension accuracy can be improved. Incidentally, when compared with patterning accuracy, it was ± 0.1 μm in the method of the present invention compared with ± 0.6 μm of the conventional method.
As a result, the width accuracy of the discharge chamber is improved, the surface roughness of the diaphragm is reduced, and variations in the thickness of the diaphragm are reduced.

As described above, according to the method of manufacturing the ink jet head of the present embodiment, the method of forming each part such as the discharge chamber after bonding the silicon substrate and the electrode glass substrate facilitates handling. Further, it is possible to reduce the cracking of the substrate and to increase the diameter of the substrate. If the diameter can be increased, a large number of inkjet heads can be taken out from a single substrate, so that productivity can be improved.
In addition, since the dry etching method is used when patterning the etching mask in the discharge chamber, the etching mask is free from dripping and the width accuracy of the discharge chamber can be improved.
Since the discharge chamber is etched in two stages, dry etching and wet etching, the width accuracy of the discharge chamber is improved, the surface roughness of the diaphragm is reduced, and variations in the thickness of the diaphragm are reduced. Can do.
Furthermore, since the dry etching method is employed in the discharge chamber etching process, the state in which the substrate is immersed in the chemical solution is less than that in the conventional method, and defects in which the chemical solution enters the gap between the electrodes can be reduced.

  In the above embodiment, the method for manufacturing an ink jet head has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the idea of the present invention. For example, by changing the liquid material ejected from the nozzle holes, in addition to inkjet printers, the production of color filters for liquid crystal displays, the formation of light-emitting portions of organic EL display devices, the microarray of biomolecule solutions used for genetic testing, etc. It can be used as a droplet discharge device for various uses such as manufacture of

1 is an exploded perspective view showing a schematic configuration of an inkjet head according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the inkjet head showing a schematic configuration of the right half of FIG. 1. FIG. 3 is a top view of the inkjet head of FIG. 2. The top view which shows a part of electrode glass substrate. The expanded sectional view of the equipotential contact part of an electrode glass substrate. Sectional drawing of the manufacturing process which shows the manufacturing method of an inkjet head. Sectional drawing which shows the manufacturing process following FIG. The comparison explanatory drawing of the conventional method of this invention and the method of this invention of the patterning method of the etching mask with respect to a silicon substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle plate, 2 Cavity plate, 3 Electrode substrate, 4 Drive control circuit, 10 Inkjet head, 11 Nozzle hole, 12 Recessed part, 13 Orifice, 14 Diaphragm part, 21 Discharge chamber, 22 Vibration plate, 23 Reservoir, 24 Recessed part, 25 Concave part, 26 Insulating film, 27 Ink protective film, 28 Common electrode, 29 Electrode extraction part, 31 Individual electrode, 32 Concave part, 33 Equipotential contact, 34 Concave part, 35 Ink supply port, 37 Sealing material, 38 Air opening hole, 39 connection part, 200 silicon substrate, 201 boron doped layer, 204 TEOS etching mask, 300 glass substrate, 301 electrode glass substrate.

Claims (12)

In a method of manufacturing a droplet discharge head, a silicon substrate is bonded to an electrode glass substrate on which individual electrodes have been formed in advance, and then the silicon substrate is thinned, and then an etching mask is patterned to form a recess serving as a discharge chamber by etching. ,
A method of manufacturing a droplet discharge head, wherein the etching mask is patterned by dry etching.   2. The method of manufacturing a droplet discharge head according to claim 1, wherein the silicon etching of the concave portion serving as the discharge chamber is performed first by dry etching and finally by wet etching.   3. The dry etching is performed until the thickness of the bottom of the concave portion serving as the discharge chamber becomes a value close to a target value, and then the wet etching is performed until the target value is reached by switching to the wet etching. A method for manufacturing the liquid droplet ejection head as described.   4. The method of manufacturing a droplet discharge head according to claim 2, wherein the dry etching of the concave portion serving as the discharge chamber is anisotropic dry etching by ICP discharge. 5. The method of manufacturing a droplet discharge head according to claim 4, wherein the anisotropic dry etching uses SF ₆ and CF ₄ or C ₄ F ₈ as an etching gas.   4. The method for manufacturing a droplet discharge head according to claim 2, wherein a low concentration potassium hydroxide aqueous solution is used in wet etching of the concave portion serving as the discharge chamber.   7. The method of manufacturing a droplet discharge head according to claim 1, wherein the patterning of the etching mask is performed by RIE dry etching.   8. The manufacturing method of a droplet discharge head according to claim 1, wherein a silicon single crystal substrate having a (110) plane orientation in which a boron-doped layer having a required thickness is formed is used as the silicon substrate. Method.   9. The concave portion serving as a reservoir is further formed in the silicon substrate by wet etching, and the thickness of the bottom portion of the reservoir is formed to be thicker than the thickness of the bottom portion of the discharge chamber. A manufacturing method of a droplet discharge head described in 1.   The electrode glass substrate is formed with equipotential contacts that short-circuit with all of the individual electrodes, and the equipotential contacts are formed so as to contact the silicon substrate when anodic bonded to the silicon substrate. A method for manufacturing a droplet discharge head according to claim 1.   The electrode glass substrate is provided with an air opening hole that communicates with a recess in which the individual electrode is formed and a recess in which the equipotential contact is formed, and the air opening hole is formed between the electrode glass substrate and the silicon substrate. 11. The method of manufacturing a droplet discharge head according to claim 10, wherein the droplet discharge head is opened until anodic bonding and closed after anodic bonding. A method for manufacturing a droplet discharge device, comprising: manufacturing a droplet discharge device using the method for manufacturing a droplet discharge head according to claim 1.

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