JP2009232641A - Electrostatic actuator, method for manufacturing same, liquid drop discharge head, liquid cartridge, image forming apparatus, micro pump, and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an unevenness in property of an electrostatic actuator by introducing gas and liquid serving as a hydrophobic film to a cavity of the actuator without stagnation even when foreign materials adhere to clog a part through which an air introducing part communicates with a communicating part. <P>SOLUTION: In order to improve the durability of the cavity 13 between an oscillating plate 12 and a fixed electrode 14, the gas or the like is introduced to a communicating passage 15 from the air introducing hole communicating with the communicating passage 15 which communicates with the cavity 13. In a board side having the fixed electrode 14 of an air opening part 16, an air opening groove 45 is provided. Even when the foreign materials enter the air opening part 16 from an air opening hole 42 in a production process, the gas or the like can be introduced into the cavity 13 through the air opening groove 45 provided in the air opening part 16 to reduce the unevenness in the property of the electrostatic actuator and improve an accuracy. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrostatic actuator, a manufacturing method thereof, a droplet discharge head, a liquid cartridge, an image forming apparatus, a micropump, and an optical device, and particularly to improvement of mass productivity.

  A liquid droplet ejection head used in an image recording apparatus such as a printer, a facsimile apparatus, a copying apparatus, or a plotter or an ink jet recording apparatus used as an image forming apparatus includes a nozzle that ejects liquid droplets and a liquid chamber (discharge chamber) that communicates with the nozzle. And an actuator means for generating energy for pressurizing the ink in the liquid chamber, and pressure is applied to the recording liquid in the liquid chamber by the energy generated by the actuator means. Droplets are ejected from the nozzle.

  Droplet discharge heads that use piezoelectric actuators such as electromechanical transducers, those that use thermal actuators that use film boiling for electrothermal transducers, and electrostatic forces between the diaphragm and electrodes Some of them use electrostatic actuators. Among them, droplet discharge heads using electrostatic actuators are smaller than other types of droplet discharge heads in terms of size, speed, density, and power saving. Because of its superiority, development is actively underway.

  In a droplet discharge head using this electrostatic actuator, the size (gap length) accuracy of the gap (gap) between the diaphragm and the electrode greatly affects its characteristics. If the variation in the characteristics of the actuator is large, the printing accuracy and the reproducibility of the image quality are remarkably lowered. In order to reduce the voltage, the gap space must be about 0.1 to 0.5 μm, and very high dimensional accuracy is required.

  As a conventional inkjet head, for example, as described in Patent Document 1 and Patent Document 2, a substrate (cavity substrate) on which a pressurized liquid chamber and a vibration plate are formed, a concave portion serving as a gap (vibration chamber), and It is formed by bonding a substrate (glass substrate) on which segment electrodes are formed. However, in such a head that joins two substrates to form a gap between the diaphragm and the electrode, due to dimensional variations during processing in many steps such as recess formation, electrode formation, and bonding, As a result, it is difficult to obtain an actuator having high accuracy and high reliability.

  Therefore, for example, as described in Patent Document 3, a diaphragm facing the individual electrode is formed by sacrificial layer etching on the first substrate through a gap formed by the individual electrode and sacrificial layer etching, It is known to form a pressure chamber groove on the second substrate and bond the second substrate on the first substrate to form an ink jet head to suppress variation in gap height. .

In the electrostatic actuator, for the purpose of eliminating the differential pressure between the internal pressure of the air gap and the atmospheric pressure or improving the reliability of the actuator, a communication path that communicates each air gap is provided to introduce gas into the air gap. . For example, as disclosed in Patent Document 3, in order to form a hydrophobic film inside the gap between the diaphragm and the individual electrode for the purpose of improving the durability of the actuator, a communication path communicating with the actuator gap, An air opening part that connects the communication path to the outside is provided, and gas and liquid that becomes a hydrophobic film are introduced from the air opening part through the communication path into the actuator gap, and after forming the hydrophobic film on the inner surface of the gap, the atmosphere is opened. What sealed the part with the sealing material is known.
JP 2007-237417 A JP 2007-38583 A JP 2007-77864 A

  In the actuator substrate described in Patent Document 3, the actuator gap, the communication path, and the atmosphere opening portion are formed by a single sacrificial layer etch process, and a gas or liquid that becomes a hydrophobic film is released from the atmosphere opening portion into the actuator gap. In the case of introduction into the air opening, it is necessary to open an air opening hole in a portion corresponding to the diaphragm of the actuator in the air opening portion. When foreign matter adheres to the part that communicates with the atmosphere opening part and the communication part during the process of introducing the gas or liquid that forms the hydrophobic film by opening the atmosphere opening hole in this way, hydrophobicity is caused into the actuator gap. In some cases, the gas or liquid that forms the film cannot be introduced sufficiently or at all, and the desired actuator performance cannot be obtained.

  The present invention eliminates such a problem and forms a groove in the lower layer below the air gap of the atmosphere opening portion even if foreign matter adhering to the portion communicating with the atmosphere introduction portion and the communication portion adheres. , An electrostatic actuator that can introduce a gas and a liquid that form a hydrophobic film into the actuator gap without delay, a liquid droplet ejection head that includes the electrostatic actuator, a liquid cartridge that integrates the liquid droplet ejection head, and the liquid It is an object of the present invention to provide an image forming apparatus equipped with a droplet discharge head or a liquid cartridge, a micropump using the electrostatic actuator, and an optical device.

  An electrostatic actuator according to the present invention includes a deformable diaphragm serving as a movable electrode, and a fixed electrode disposed opposite to the diaphragm via a gap formed by sacrificial layer etching. In the electrostatic actuator that deforms with an electrostatic force, the electrostatic actuator includes an air release portion having a communication passage communicating with the gap and an air release hole communicating the communication passage with the outside, and the fixed electrode of the air release portion is included. An air release groove is provided on the substrate side.

  The atmosphere opening portion groove communicates with the communication path. In addition, it is desirable to have a plurality of the atmosphere opening groove.

  The manufacturing method of the electrostatic actuator according to the present invention includes a deformable diaphragm serving as a movable electrode, a fixed electrode disposed opposite to the diaphragm via a gap formed by sacrificial layer etching, and the gap. A communication passage that communicates with the atmosphere, an atmosphere opening portion that communicates the communication passage with the outside, and an atmosphere opening portion groove provided on the substrate side having the fixed electrode of the atmosphere opening portion, and the diaphragm is deformed by electrostatic force The manufacturing method of the electrostatic actuator to be performed is characterized in that the gap, the communication path, the atmosphere opening portion and the atmosphere opening portion groove are formed by the same sacrificial layer etching.

  The droplet discharge head according to the present invention includes a first substrate having the electrostatic actuator, a second substrate forming a liquid chamber for storing a liquid, and a third substrate having a nozzle hole. It is characterized by being configured.

  The liquid cartridge according to the present invention is characterized in that the droplet discharge head and a liquid tank for supplying a liquid to the droplet discharge head are integrated.

  The image forming apparatus of the present invention includes the droplet discharge head or the liquid cartridge, and records an image by discharging ink droplets from nozzle holes of the droplet discharge head.

  The micropump of the present invention includes the electrostatic actuator, and transports a liquid by deforming a diaphragm of the electrostatic actuator with an electrostatic force.

  The optical device according to the present invention includes the electrostatic actuator, the surface of the diaphragm of the electrostatic actuator is formed by a reflecting surface, and the diaphragm is deformed by an electrostatic force to scatter incident light. And

  In the electrostatic actuator of the present invention, in order to improve the durability of the gap between the diaphragm and the fixed electrode, gas or the like is introduced from the air introduction hole that leads to the communication path that leads to the gap. Even if foreign matter enters the atmosphere opening part from the atmosphere opening hole, gas etc. can be introduced into the gap through the atmosphere opening part groove provided in the atmosphere opening part, reducing the characteristic variation of the electrostatic actuator and forming it with high accuracy it can.

  By forming the air gap, the communication path, the air opening portion, and the air opening portion groove by the same sacrificial layer etching, the mass productivity and the yield can be improved, and the manufacturing cost of the electrostatic actuator can be reduced.

  In addition, the droplet discharge head provided with this electrostatic actuator can improve the reliability by reducing variations in droplet discharge.

  Furthermore, by integrating the droplet discharge head equipped with this electrostatic actuator and the liquid tank that supplies liquid to the droplet discharge head, mass productivity and yield can be improved, and manufacturing costs can be reduced. it can.

  An image forming apparatus that has this droplet discharge head or liquid cartridge and records an image by discharging ink droplets from the nozzle holes of the droplet discharge head stably discharges ink droplets. It is possible to stably form an image and reduce manufacturing defects to reduce costs.

  In addition, a micropump having a small size and low power consumption can be realized by deforming the diaphragm of the electrostatic actuator with an electrostatic force and transporting the liquid.

  Furthermore, a compact and low power consumption optical device can be realized by forming the surface of the diaphragm of the electrostatic actuator with a reflecting surface and deforming the diaphragm with electrostatic force to scatter incident light.

  1 is a perspective view of a droplet discharge head having an electrostatic actuator according to the present invention, FIG. 2 is an exploded perspective view of the droplet discharge head, and FIG. 3 is a cross section in the direction of the long side of the liquid chamber along the plane AA in FIG. FIG. 4 and FIG. 4 are cross-sectional views in the liquid chamber long side direction along the plane BB in FIG. As shown in the figure, the droplet discharge head 100 is of a side shooter type that discharges droplets from nozzle holes provided in the substrate surface, and is an actuator substrate 1 and a second substrate that are first substrates. A flow path substrate 2 and a nozzle substrate 3 as a third substrate are sequentially laminated, and these three substrates 1 to 3 are joined to communicate with a nozzle 4 for discharging droplets via a nozzle communication path. A liquid resistance section 7 and a common liquid chamber 8 for supplying liquid (ink) to the liquid chamber (discharge chamber) 5 and the liquid chamber 6 are formed. Each liquid chamber 6 is partitioned by a liquid chamber interval wall 9.

  As shown in FIG. 2, the actuator substrate 1 includes a diaphragm 12 that forms a diaphragm region (deformable region) 12 </ b> A that forms a part of the wall surface of the liquid chamber 6, and a diaphragm region 12 </ b> A of the diaphragm 12. The individual electrodes 14 that face each other through a gap (gap) 13 formed by sacrificial layer etching are provided, and the diaphragm 12 and the individual electrodes 14 constitute an electrostatic actuator corresponding to each liquid chamber 6. The actuator substrate 1 is formed with a common communication path (communication pipe) 15 in the direction in which the nozzles 4 are arranged so that the air gaps 13 communicate with each other and communicate with the outside of the actuator substrate 1 itself. The gap 13 is communicated with the passage 15 via the individual communication passage 15A, and the other end portion of the common communication passage 15 is communicated with an atmosphere opening portion 16 for opening the common communication passage 15 to the atmosphere. The air release portion 16 is sealed with a sealant at the stage where the actuator substrate 1 is formed.

  In the actuator substrate 1, as shown in FIG. 3, an etchable electrode forming layer 24 to be an individual electrode 14 is formed on a silicon substrate 21 via an insulating film 22, and the insulating film 25 is formed on the electrode forming layer 24. Further, a sacrificial layer 27 is formed on the insulating film 25 to form the air gap 13, the common communication path 15, the individual communication path 15 </ b> A, and the air release space of the air release portion 16. As shown in FIG. 4, a sacrificial layer removal hole 29 is formed in the insulating film 28, and the sacrificial layer 27 is removed from the sacrificial layer removal hole 29 to remove the sacrificial layer 27 and the common communication path 15. In addition, the individual communication passage 15 </ b> A and the open air gap of the open air portion 16 are formed, and the diaphragm member 30 is laminated on the insulating film 28. The insulating film 25 formed on the surface of the individual electrode 14 is for preventing an electrical short circuit with the diaphragm 12 and protecting the individual electrode 14 during etching of the sacrificial layer for forming the gap 13. . In addition, the insulating film 28 on the diaphragm 12 side also prevents an electrical short circuit with the individual electrode 14, and a part of the diaphragm member 30 formed on the insulating film 28 at the time of sacrificial layer etching for forming the gap 13. It is for protecting the layer. The actuator substrate 1 is provided with a supply port 18 for supplying ink from the outside to the common liquid chamber 8 of the flow path substrate 2.

  The flow path substrate 2 joined on the actuator substrate 1 is, for example, a groove portion communicating with a silicon substrate having a crystal orientation (110), a liquid chamber (discharge chamber) 5, and each liquid chamber 6 via a fluid resistance 7. Or the common liquid chamber 8 which consists of a recessed part is provided. The nozzle substrate 3 bonded onto the flow path substrate 2 uses, for example, nickel having a thickness of 50 μm, and the nozzle 4 can be formed by a known method such as dry or wet etching or laser processing.

In the droplet discharge head 100 configured as described above, a recording liquid is discharged from a control unit (not shown) based on image data in a state where each liquid chamber 6 is filled with a liquid, for example, a recording liquid (ink). A pulse voltage of 40 V is applied to the individual electrode 14 corresponding to the nozzle 4 by the oscillation circuit. By applying this voltage, a positive charge is charged on the surface of the individual electrode 14, and a suction action by an electrostatic force acts between the individual electrode 14 and the diaphragm 12 including the diaphragm electrode, so that the diaphragm 12 moves downward. Bend. As a result, the volume of the liquid chamber 6 is expanded, and the recording liquid corresponding to that volume flows from the common liquid chamber 10 into the liquid chamber 6 via the fluid resistance portion 7. Thereafter, by setting the pulse voltage to 0 V to the individual electrode 14 (stopping the application), the diaphragm 12 bent downward by the electrostatic force returns to its original position due to its own rigidity. As a result, the pressure in the liquid chamber 6 is rapidly increased, and a recording liquid droplet is ejected from the nozzle hole 4 communicating with the liquid chamber 6. Then, by repeating this operation and continuously ejecting the recording liquid from the nozzle 4, an image is formed on a recording medium (paper) disposed facing the droplet ejection head. Here, in the electrostatic actuator, the electrostatic force acting between the individual electrode 14 and the diaphragm 12 is given by the following equation. Here, F is the electrostatic force acting between the electrodes, ε is the dielectric constant, S is the area of the opposing surfaces of the electrodes, d is the distance between the electrodes, and V is the applied voltage.
F = (εS / 2d ² ) · V ²

  That is, it can be seen that the electrostatic force F is inversely proportional to the square of the inter-electrode distance d and directly proportional to the square of the applied voltage V. Therefore, in order to reduce the driving voltage of the electrostatic actuator or the droplet discharge head 100 equipped with the electrostatic actuator, the distance (gap height: gap length) between the individual electrode 14 and the diaphragm 12 is made small. It becomes important.

  Therefore, as described above, by forming the air gap 13 by sacrificial layer etching, it is possible to stably form a fine air gap accurately and without variation, so that static characteristics with less variation in operating characteristics between the actuators can be obtained. An electric actuator can be obtained, and by applying this electrostatic actuator to the droplet discharge head 100, variations in droplet discharge characteristics between the nozzles 4 are reduced, and a high-quality image is formed. Can do.

  Next, details of the actuator substrate 1 will be described with reference to FIGS. 5 is a plan view showing the actuator substrate 1 in a transparent state, FIG. 6 is a sectional view taken along line X1-X1 in FIG. 5, FIG. 7 is a sectional view taken along line X2-X2 in FIG. FIG. 9 is a sectional view taken along line X3-X3 in FIG. 8, and FIG. 10 is a sectional view taken along line Y3-Y3 in FIG.

  The diaphragm 12 of the actuator substrate 1 is composed of the insulating film 28 and the diaphragm member 30 as described above, and the diaphragm region 12A of the diaphragm member 30 is separated by the separation groove 31 as shown in FIG. Has been. As shown in FIG. 6, the diaphragm member 30 is formed by sequentially laminating a diaphragm electrode (upper electrode) 32, a film stiffness adjusting film (nitride film) 33, a deflection preventing film 34, and a resin film 35 on an insulating film 28. Formed. Further, as shown in FIG. 5, each diaphragm region 12A on the insulating film 22 formed on the surface of the silicon substrate 21 has a short side length a and a long side length b of, for example, a short side length of 60 μm and a long side length b. Is 1000 μm.

  The gaps 13 between these diaphragm regions 12A and the individual electrodes 14 are formed by sacrificial layer etching. In the sacrificial layer etching, a sacrificial layer 27 having the height of the gap 13 is formed on the insulating film 25, and then an insulating film 28, a diaphragm electrode 32, and a film stiffness adjusting film (nitride film) 33 are sequentially stacked. Then, a sacrificial layer removal hole 29 penetrating them is formed, and the sacrificial layer 27 in the gap 13 portion is removed through the sacrificial layer removal hole 29.

  In the sacrificial layer etching for removing the sacrificial layer 27, the common communication passage 15 and the individual communication passage 15 </ b> A and the air release space 41 of the air release portion 16 are formed together with the formation of the space 13. In this manner, the gap 13 between the diaphragm and the electrode, the common communication path 15 and the individual communication path 15A, and the air release space 41 of the air release portion 16 are simultaneously formed by removing the same sacrificial layer. Alternatively, the passages can be communicated with each other, the configuration is simple, the number of manufacturing steps is small, and the mass productivity and the yield are improved.

  Here, as shown in FIG. 5, the sacrificial layer removal holes 29 are arranged at equal intervals in the long side direction of the diaphragm region 12 </ b> A and at intervals equal to or shorter than the short side length a of the diaphragm region 12 </ b> A. It is formed at the same position on the opposite side of the plate region 12A. Since the sacrificial layer etching is isotropic, the sacrificial layer removal efficiency is higher when the sacrificial layer removal hole 29 is arranged in the center in the diaphragm region 12A. However, if the sacrificial layer removal hole 29 is present in the diaphragm region 12A. Since the vibration characteristics of the actuator may be affected, the sacrificial layer removal hole 29 is preferably disposed outside the diaphragm region 12A. Further, by arranging a plurality of sacrificial layer removal holes 29, the sacrificial layer 27 can be efficiently removed, and the gap 13 can be formed efficiently.

  Further, as shown in FIG. 8, the sacrificial layer removal hole 29 for forming the open air gap 41 of the open air portion 16 efficiently takes into account the sacrificial layer 27 in consideration of the area ratio with the diaphragm region 12A. The sacrificial layer removal hole 29 is disposed so as to be etched.

  After sacrificial layer etching, the sacrificial layer removal hole 29 is completely sealed with a film deflection preventing film 34. Thereafter, although not shown, a wiring for taking out to the external electrode and a supply port 18 for supplying the recording liquid to the common liquid chamber 8 are formed, and a resin film 35 in contact with the droplet is formed. Further, an air opening hole 42 communicating with the internal air opening air gap 41 is opened in the air opening portion 16, and the air opening of the air gap 13 through the air opening hole 42, the air air opening air gap 41, the common communication path 15 and the individual communication path 15 </ b> A or the air gap 13 is introduced with a hydrophobic film forming material such as hexamethyldisilazane (HMDS). At this time, in order to form the atmosphere opening hole 42 of the atmosphere opening portion 16, the vibration plate 12 in the area of the atmosphere opening portion 16 is removed by a laser method or physical. Alternatively, the air opening hole 42 of the air opening portion 16 can be formed by a litho-etching method capable of microfabrication, so that the area of the air opening portion 16 can be reduced as compared with the laser method and the physical method, and the generation of foreign matters can be suppressed. In addition, since the surface state is simple, there is almost no influence on the next step, which is more preferable. Then, an air opening hole sealing film is formed by spray coating, vapor deposition polymerization or the like. Alternatively, an inorganic material, such as a silicon oxide film, may be used as the air opening hole sealing film by the CVD method.

  Here, when a foreign matter larger than the atmosphere opening hole 42 adheres to the atmosphere opening portion 16, the foreign matter can be removed relatively easily by air blow or the like, but when a foreign matter smaller than the atmosphere opening hole 42 adheres, the atmosphere opening portion 16 The foreign material enters the step 16 and cannot be easily removed. Especially when this foreign material blocks the gap of the common communication path 15 communicating from the air opening gap 41, the hydrophobic film forming material to the gap 13 of the actuator in a later step Therefore, it is impossible to obtain desired operating characteristics. However, since the air release portion groove 45 is formed below the air release hole 42, even if foreign matter smaller than the air release hole 42 adheres to the air release portion 16, A hydrophobic film-forming material can be introduced into the gap 13. Here, the width of the air opening portion groove 45 is preferably narrow because it can accommodate small foreign substances, and the number of the air opening portion grooves 45 is preferably as large as possible. Thereby, an electrostatic actuator with no malfunction is obtained, and the manufacturing yield of the electrostatic actuator is improved.

  Next, the manufacturing process of the actuator substrate 1 will be described with reference to FIGS. 11 is a manufacturing process diagram showing a portion along line X1-X1 in FIG. 5, FIG. 12 is a manufacturing process diagram showing a part along line X2-X2 in FIG. 5, and FIG. 13 is along a line X3-X3 in FIG. FIG. 14 is a manufacturing process diagram showing a portion along the line Y3-Y3 in FIG.

  As shown in FIGS. 11, 12, 13, and 14A, for example, an insulating film (thermal oxide film) having a thickness of 1.5 μm is formed on the surface (here, both surfaces) of a silicon (Si) substrate 21 having a thickness of 400 μm. ) 22 is formed, and phosphorus-doped polysilicon (symbol 14A in the part of the air opening portion 16 is attached) as an electrode forming layer for forming the individual electrode 14 on the insulating film 22 has a thickness of 0.3 μm. A film is formed. Then, a separation groove 40 is formed in the polysilicon (electrode forming layer) by a litho-etching method, and is separated and patterned into the individual electrode 14 and the portion 51 constituting the partition wall. The portion 53 to be formed is removed. Thereafter, a CVD oxide film is deposited to a thickness of 0.1 μm, and an insulating film 25 is formed on the individual electrode 14 made of polysilicon and the portion 51 constituting the partition and in the isolation trench 40. Then, the insulating film 25 of the portion 54 that later forms the common communication passage 15, the portion that forms the individual communication passage 15 </ b> A, the portion 55 that forms the air opening gap 41, and the portion 56 that forms the air opening groove 45 is formed by lithoetching. Remove.

  Next, as shown in FIGS. 11, 12, 13, and 14 (b), non-doped polysilicon is formed as a sacrificial layer 27 on the insulating film 25 to a thickness of 0.2 μm, which is a gap, by CVD. To do. Then, polysilicon is separated and patterned into a portion 57 that becomes the gap 13, a portion 58 that constitutes the partition wall, a portion 59 that becomes the individual communication passage 15 </ b> A, and a portion 60 that becomes the common communication passage 15 by lithoetching, thereby forming the separation groove 61. At the same time, the portion corresponding to the portion 53 to be the supply port 18 is removed. At this time, as shown in FIG. 13 and FIG. 14B, the portion that becomes the atmosphere opening portion 16 is separated and patterned into a portion 70 that becomes the atmosphere opening air gap 41 and a portion 71 that constitutes the partition wall. 61 is formed. In this way, by using polysilicon as the material for forming the sacrificial layer, a general-purpose technique generally known as a sacrificial layer removal step can be used, and there is selectivity with other materials and freedom of the process. High degree, low cost, excellent mass productivity and stable actuator can be obtained.

  Thereafter, the sacrificial layer 27 is formed, and the atmosphere 57 of the atmosphere opening portion 16 is formed on the portion 57 serving as the gap 13, the portion 58 constituting the partition wall, the portions 59 and 60 serving as the individual communication path 15 </ b> A and the common communication path 15. A CVD oxide film is deposited on the portion 70 serving as the open air gap 41, the portion 59 serving as the common communication path, and the portion 71 constituting the partition wall to form the insulating film 28 with a thickness of 0.1 μm. At this time, the insulating film 28 is also formed in the isolation trench 61.

  Next, as shown in FIGS. 12, 13, and 14 (c), a phosphorus-doped polysilicon layer to be the diaphragm electrode layer 32 is formed on the insulating film 28 with a thickness of 0.1 μm, and this polysilicon layer is formed. The diaphragm electrode layer 32 and the part 61 constituting the partition wall are separated by the litho-etching method, and the part 53 to be the supply port 18 is removed to form an opening. At the same time, in order to prevent the diaphragm electrode layer 32 made of the same material as the sacrificial layer 27 from being etched during the sacrificial layer etching, an opening 62 having a larger opening diameter than the sacrificial layer removal hole 29 to be formed later is formed. . Further, in the portion that becomes the atmosphere opening portion 16, as shown in FIGS. 13 and 14, the polysilicon layer that becomes the diaphragm electrode layer 32 is separated and patterned by the litho-etching method, and later formed. An opening 62 larger than the layer removal hole 29 is formed. Then, a nitride film having a thickness of 0.15 μm is deposited on the diaphragm electrode layer 32 as the stiffness adjusting layer 33 of the diaphragm 12 by the LP-CVD method. The rigidity adjusting layer 33 made of the nitride film is also formed in the opening 62 to cover the end face side of the opening 62 of the diaphragm electrode layer 32.

  Thereafter, as shown in FIGS. 11, 12, 13, and 14D, a sacrificial layer removal hole 29 having an opening diameter of 2 μm is formed through the nitride film as the film stiffness adjusting layer 33 and the insulating film 28 by lithoetching. Further, the nitride film 33, the insulating film 27, and the insulating film 28 in the portion that becomes the supply port 18 are removed to form the processing hole 63 of the supply port 18. Then, for example, by performing sacrificial layer etching such as SF6 plasma processing or dry etching with XeF2 gas to completely remove the sacrificial layer 27 in the portion 57 that becomes the gap 13, the gap 13, the individual communication path 15A, and the common communication path 15A are shared. A passage 15 is formed. Although the sacrificial layer etching is performed by dry etching, a wet etching method using a TMAH solution or a KOH solution may be used.

  At this time, the sacrificial layer removal hole 29 having an opening diameter of 2 μm is formed also in the atmosphere opening portion 16 through the nitride film and the insulating film 28 as the stiffness adjusting layer 33 by the lithoetch method, as shown in FIG. 13 and FIG. To do. The sacrificial layer etching completely removes the sacrificial layer 27 and the lower electrode layer 14 </ b> A of the portion 55 that becomes the air opening gap 41, the portion 56 that becomes the air opening groove 45, and the portion 54 that becomes the common communication path 15. The air gap 41, the air release groove 45, and the common communication path 15 are formed.

  Next, as shown in FIGS. 11, 12, 13, and 14 (e), for the purpose of sealing the sacrificial layer removal hole 29, a film deflection preventing film 34 is formed by atmospheric pressure CVD. The film thickness at this time is a film thickness that can seal the sacrificial layer removal hole 29, for example, a thickness of 0.6 μm. By performing this step, the air gap 13 and the air opening air gap are sealed and completely blocked from the outside air.

  Thereafter, as shown in FIG. 11 and FIG. 12F, after removing the sealing film 34 in the portion serving as the supply port 18 by lithoetching, the silicon substrate 21 is formed by anisotropic etching, for example, ICP etcher. The supply port 18 is formed by etching so as to penetrate from the front surface to the back surface. Here, by forming the supply port 18 by anisotropic etching, it is possible to obtain a high effect in terms of processing shape controllability, fine workability, processing accuracy, and higher density. Thereafter, as shown in FIG. 11 and FIG. 12G, a resin film 35 as a wetted film is formed to a thickness of 1 μm on the entire surface of the actuator substrate by an intermediate deposition method with excellent coverage. Thereafter, only the electrode wiring take-out pad portion (not shown) is opened by the lithoetch method. Here, examples of the material used for the resin film 35 include a PBO film (polybenzoxazole), a polyimide film, and polyparaxylylene. However, the material has corrosion resistance against droplets and can be formed by vapor deposition polymerization. Other materials may be used.

  Next, as shown in FIG. 13 and FIG. 14F, the air opening hole 42 is opened by a lithoetch method. Thus, the air gap 13 communicates with the atmosphere via the individual communication passage 15 </ b> A, the common communication passage 15, the air release air gap 41, and the air release hole 42. In order to improve the reliability of the electrostatic actuator, for example, a water repellent material such as HMDS (hexamethyldisilazane) is passed through the air opening hole 42 through the air opening air gap 41, the common communication passage 15 and the individual communication passage 15A. 13 is introduced. Foreign matter may adhere to the air opening hole 42 during the process of introducing the hydrophobic material into the gap 13 after opening the air opening hole 42. If foreign matter larger than the air opening hole 42 adheres to the atmosphere opening portion 16, the foreign matter can be removed relatively easily by air blow or the like, but if a foreign matter smaller than the atmosphere opening hole 42 adheres, A foreign material enters the step and cannot be easily removed. In particular, when the foreign material blocks the gap of the common communication path 15 communicating with the air opening gap 41, a hydrophobic film forming material is introduced into the gap 13 of the electrostatic actuator. It is impossible to obtain desired operating characteristics. However, since the air release portion groove 45 is formed under the air release hole 42, even if a foreign substance smaller than the air release hole 42 adheres to the air release portion 16, it is hydrophobic through the air release portion groove 45. A film forming material can be introduced into the gap 13.

  Thereafter, as shown in FIG. 13 and FIG. 14G, the sealing material 36 is formed so that the region including the air release hole 42 is covered in order to prevent foreign matter, moisture, etc. from entering from the air release hole 42 to the actuator gap 13. Seal completely. The sealing material may be a silicon oxide film by atmospheric pressure CVD or a resin agent. Through the above steps, the actuator substrate 1 on which the electrostatic actuator according to the present invention is formed is completed. Then, by sequentially stacking the actuator substrate 1, the flow path substrate 2 and the nozzle substrate 3, the droplet discharge head 100 including the electrostatic actuator can be manufactured.

  Next, another electrostatic actuator used in the droplet discharge head 100 will be described with reference to FIGS. 15 is a plan view of another atmosphere opening portion 16 of the actuator substrate 1, FIG. 16 is a sectional view taken along line X4-X4 in FIG. 15, and FIG. 17 is a sectional view taken along line Y4-Y4 in FIG. 18 is an enlarged plan view around the sacrificial layer removal hole 29 in FIG. 15, and FIG. 19 is a cross-sectional view taken along the line Y5-Y5 in FIG.

  In the atmosphere opening portion 16 of the actuator substrate 1, the sacrificial layer removal hole 29 is disposed in a region 77 where the lower electrode layer is left in the region of the air release hole 42, and the diaphragm 12 is fixed around the sacrifice layer removal hole 29. A pillar 78 is arranged. By disposing the fixed column 78 for fixing the diaphragm 12 in this way, the air release gap 41 is formed even if the area of the air release portion 16 is larger than the short side length of the vibration region 12A (FIG. 5) of the actuator. It is possible to prevent the vibration plate 12 from being bent later, or in the worst case, to be broken, and to prevent the manufacturing yield from being lowered. Further, the number and arrangement of the sacrificial layer removal holes 29 in the atmosphere opening portion 16 can be determined in consideration of the balance between the area of the atmosphere opening portion 16 and the formation of the actuator gap, according to the area of the atmosphere opening portion 16. Therefore, the sacrificial layer of the air opening air gap 41 can be completely removed in the etching time for completely removing the sacrificial layer of the actuator air gap 13, and the insulating films 27 and 28 in the actuator air gap portion are over-etched and become thinner than desired, and the desired characteristics. It is possible to prevent inconveniences such as failure to obtain, and to further increase design flexibility while solving process issues, ensuring high accuracy and reliability, and improving manufacturing yield. Can do.

  Therefore, the present invention can be provided for an ink cartridge in which the droplet discharge head 100 is integrated or a droplet discharge recording apparatus equipped with the droplet discharge head 100. In addition, it is possible to manufacture the droplet discharge head 100 having high precision, high density, and high reliability, which is excellent in dimensional control having good productivity and production efficiency, which has been difficult with the prior art.

  An ink cartridge in which the droplet discharge head 100 is integrated will be described with reference to FIG. The ink cartridge 80 is obtained by integrating a droplet discharge head 100 having nozzles 81 and the like and an ink tank 82 that supplies ink to the droplet discharge head 100. As described above, when the ink tank 82 is the integrated droplet discharge head 100, the yield and reliability of the ink cartridge 80 can be improved by increasing the reliability of the actuator unit, and the cost of the ink cartridge 80 can be reduced. Can be achieved.

  Next, an example of an ink jet recording apparatus equipped with the droplet discharge head 100 will be described with reference to a perspective view of FIG. 21 and a side view showing a configuration of a mechanism portion of FIG. The ink jet recording apparatus 90 includes a carriage 98 that can move in the main scanning direction inside the apparatus main body, a droplet discharge head 100 mounted on the carriage 98, an ink cartridge 99 that supplies ink to the droplet discharge head 100, and the like. A paper feed cassette (or a paper feed tray) 93 on which a large number of sheets 92 can be stacked from the front side is detachably attached to the lower part of the apparatus main body. Further, it has a manual feed tray 94 that is opened to manually feed the paper 92, takes in the paper 92 fed from the paper feed cassette 93 or the manual feed tray 94, and records a required image by the printing mechanism 91. Thereafter, the paper is discharged onto a paper discharge tray 95 mounted on the rear side.

  The printing mechanism 91 holds a carriage 98 slidably in the main scanning direction by a main guide rod 96 and a sub guide rod 97 which are guide members horizontally mounted on left and right side plates (not shown). A droplet discharge head 100 that discharges ink droplets of each color (Y), cyan (C), magenta (M), and black (Bk) is arranged in a direction intersecting the main scanning direction with a plurality of ink discharge ports (nozzles). However, it is mounted with the ink droplet ejection direction facing downward. Further, each ink cartridge 99 for supplying ink of each color to the droplet discharge head 100 is replaceably mounted on the carriage 98.

  The ink cartridge 99 is provided with an air outlet communicating with the atmosphere at the upper side, and a supply port for supplying ink to the droplet discharge head 100 at the lower side, and has a porous body filled with ink inside. The ink supplied to the droplet discharge head 100 is maintained at a slight negative pressure by the capillary force of the material. Further, although the droplet discharge head 100 of each color is used as the droplet discharge head 100, one liquid chamber discharge head having nozzles for discharging ink droplets of each color may be used.

  Here, the carriage 98 is slidably fitted to the main guide rod 96 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 97 on the front side (upstream side in the paper conveyance direction). is doing. In order to move and scan the carriage 98 in the main scanning direction, a timing belt 104 is stretched between the driving pulley 102 and the driven pulley 103 that are rotationally driven by the main scanning motor 101, and the timing belt 104 is moved to the carriage 98. The carriage 98 is reciprocally driven by forward and reverse rotations of the main scanning motor 101.

  On the other hand, in order to convey the paper 92 set in the paper feed cassette 93 to the lower side of the droplet discharge head 100, the paper feed roller 105 and the friction pad 106 for separating and feeding the paper 92 from the paper feed cassette 93, and the paper 92 A guide member 107 that guides the sheet 92, a conveying roller 108 that reverses and conveys the fed paper 92, a conveying roller 109 that is pressed against the peripheral surface of the conveying roller 108, and a feeding angle of the sheet 92 from the conveying roller 108. And a tip roller 110 for defining. The transport roller 108 is rotationally driven through a gear train by a sub-scanning motor.

  In addition, a printing receiving member 111 that is a sheet guide member is provided to guide the sheet 92 sent out from the conveying roller 108 corresponding to the moving range of the carriage 98 in the main scanning direction on the lower side of the droplet discharge head 100. Yes. A conveyance roller 112 and a spur 113 that are rotationally driven to send the paper 92 in the paper discharge direction are provided on the downstream side of the printing receiving member 111 in the paper conveyance direction, and the paper 92 is further discharged to the paper discharge tray 95. A roller 114, a spur 115, and guide members 116 and 117 that form a paper discharge path are disposed.

  During recording by the inkjet recording apparatus 90, the droplet discharge head 100 is driven in accordance with the image signal while moving the carriage 98, thereby discharging ink onto the stopped sheet 92 to record one line. Thereafter, after the sheet 92 is conveyed by a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 92 reaches the recording area, the recording operation is terminated and the paper 92 is discharged.

  In addition, a recovery device 117 for recovering the ejection failure of the droplet ejection head 100 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 98. The recovery device 117 includes a cap unit, a suction unit, and a cleaning unit. During printing standby, the carriage 98 is moved to the recovery device 117 side, and the droplet discharge head 100 is capped by the capping unit to keep the discharge port portion in a wet state, thereby preventing discharge failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.

  In addition, when ejection failure occurs, the ejection port (nozzle) of the droplet ejection head 100 is sealed with a capping unit, and bubbles and the like are sucked out from the ejection port with the suction unit through the tube, and adhere to the surface of the ejection port. The discharged ink, dust, etc. are removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, since the ink jet recording apparatus 90 includes the liquid droplet ejection head 100 having the electrostatic actuator, there is no ink droplet ejection failure due to vibration plate drive failure, and stable ink droplet ejection characteristics. As a result, the image quality is improved. In addition, since a head that can be driven at a low voltage is mounted, the power consumption of the entire inkjet recording apparatus can be reduced.

  In the above description, the case where the droplet discharge head 100 is used in the inkjet recording apparatus 90 has been described. However, the droplet discharge head 100 may be applied to an apparatus that discharges droplets other than ink, for example, a liquid resist for patterning. good.

  Next, the case where the electrostatic actuator of the droplet discharge head 100 is applied to a micropump will be described with reference to the cross-sectional view of FIG. The micropump 200 is provided with a plurality of diaphragms 202 provided with electrodes 201, and has a structure in which a fluid flows in a flow path 203. Then, by sequentially driving the diaphragm 203 from the right side in the drawing, the fluid in the flow path 203 flows in the direction of the arrow 204, and the fluid can be transported. Although the micropump 200 is shown as having a plurality of diaphragms 202, the number of diaphragms 202 may be one, and a valve or the like may be provided to increase transport efficiency.

  The electrostatic actuator of the droplet discharge head 100 can also be applied to an optical device. For example, as shown in the cross-sectional view of FIG. 24, the optical device 210 is provided with a plurality of electrodes 211 and a diaphragm 212 facing each electrode 211. The diaphragm 212 also serves as a mirror. A dielectric multilayer film or a metal film is preferably formed on the surface of the vibration plate 212 in order to increase the reflectance. Light emitted from the light source 213 to the optical device 210 is irradiated to the diaphragm 212 through the lens 214. When the diaphragm 211 is not driven by the electrode 211, the light incident on the diaphragm 212 is reflected at the same angle as the incident angle and enters the projection lens 215. When the vibration plate 212 is driven by the electrode 211 in this state, the vibration plate 212 of that portion becomes a concave mirror, so that the reflected light becomes divergent light. In this way, a light modulation device can be realized.

  An optical modulation device to which the optical device 210 is applied will be described. As shown in the perspective view of FIG. 25, the light modulation device 220 arranges the optical device 210 in two dimensions. Then, light from the light source 213 enters the diaphragm 212 via the lens 214, and each diaphragm 212 is driven independently. At this time, the light incident on the part where the diaphragm 211 is not driven by the electrode 211 is incident on the projection lens 215, and the part where the diaphragm 212 is deformed by applying a voltage to the electrode 211 is concave. The incident light diverges and hardly enters the projection lens 215 as a mirror. An image can be displayed on the screen by projecting the light incident on the projection lens 215 onto a screen (not shown). 25 shows the light modulation device 220 in which the electrodes 211 are arranged in 4 × 4, this is not restrictive, and a large number of electrodes 211 may be arranged.

  Further, the electrostatic actuator of the droplet discharge head 100 can be applied to other optical devices and microactuators.

1 is a perspective view of a droplet discharge head having an electrostatic actuator according to the present invention. It is a disassembled perspective view of a droplet discharge head. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is a top view which shows an actuator board | substrate in a permeation | transmission state. It is X1-X1 sectional drawing of FIG. It is X2-X2 sectional drawing of FIG. It is a top view which shows the air release part of an actuator board | substrate. It is X3-X3 sectional drawing of FIG. It is Y3-Y3 sectional drawing of a figure. FIG. 6 is a manufacturing process diagram illustrating a portion along line X1-X1 in FIG. 5; FIG. 6 is a manufacturing process diagram illustrating a portion along line X2-X2 in FIG. 5; It is a manufacturing process figure which shows the part which follows the X3-X3 line | wire of FIG. It is a manufacturing process figure which shows the part which follows the Y3-Y3 line | wire of FIG. It is a top view of the other air release part of an actuator substrate. It is X4-X4 sectional drawing of FIG. It is Y4-Y4 sectional drawing of FIG. FIG. 16 is an enlarged plan view around a sacrificial layer removal hole in FIG. 15. It is Y5-Y5 sectional drawing of FIG. FIG. 3 is a perspective view of an ink cartridge in which a droplet discharge head is integrated. 1 is a perspective view of an ink jet recording apparatus equipped with a droplet discharge head. It is a side view which shows the structure of the mechanism part of an inkjet recording device. It is sectional drawing which shows the structure of the micropump using an electrostatic actuator. It is sectional drawing which shows the structure of the optical device which uses an electrostatic actuator. It is a perspective view which shows the optical device arrange | positioned two-dimensionally.

Explanation of symbols

100; droplet discharge head, 1; actuator substrate, 2; flow path substrate,
3; nozzle substrate, 4; nozzle, 5; liquid chamber (discharge chamber), 6; liquid chamber, 7;
8; common liquid chamber, 9; liquid chamber spacing, 12; diaphragm, 13; gap (gap),
14; Individual electrode, 15; Common communication path (communication pipe), 16;
21; Silicon substrate, 22; Insulating film, 24; Electrode forming layer, 25; Insulating film,
27; sacrificial layer, 28; insulating film, 29; sacrificial layer removal hole, 30; diaphragm member,
32; Diaphragm electrode (upper electrode), 33; Film stiffness adjusting film (nitride film), 34; Deflection preventing film,
35; resin film, 80; ink cartridge, 90; ink jet recording apparatus,
200; micropump, 210; optical device, 220; light modulation device.

Claims (10)

An electrostatic type comprising: a deformable diaphragm serving as a movable electrode; and a fixed electrode opposed to the diaphragm via a gap formed by sacrificial layer etching, wherein the diaphragm is deformed by an electrostatic force. In the actuator
A communication passage that communicates with the air gap, and an atmosphere opening portion that has an atmosphere opening hole that communicates the communication passage with the outside, and an atmosphere opening portion groove is provided on the substrate side of the atmosphere opening portion that has the fixed electrode. Features an electrostatic actuator.   The electrostatic actuator according to claim 1, wherein the atmosphere opening portion groove communicates with the communication path.   3. The electrostatic actuator according to claim 1, wherein the electrostatic actuator has a plurality of the atmosphere opening portion grooves. A deformable diaphragm serving as a movable electrode, a fixed electrode opposed to the diaphragm via a gap formed by sacrificial layer etching, a communication path communicating with the gap, and the communication path outside A method for producing an electrostatic actuator comprising an atmosphere opening portion communicated with the substrate and an atmosphere opening portion groove provided on the substrate side having the fixed electrode of the atmosphere opening portion, wherein the diaphragm is deformed by an electrostatic force.
The method for manufacturing an electrostatic actuator, wherein the gap, the communication path, the atmosphere opening portion, and the atmosphere opening portion groove are formed by the same sacrificial layer etching.   A first substrate having the electrostatic actuator according to any one of claims 1 to 3, a second substrate forming a liquid chamber for storing a liquid, and a third substrate having a nozzle hole are sequentially stacked. A droplet discharge head characterized by being configured as described above.   6. A liquid cartridge comprising the droplet discharge head according to claim 5 and a liquid tank for supplying a liquid to the droplet discharge head.   An image forming apparatus comprising the droplet discharge head according to claim 5, wherein an image is recorded by discharging an ink droplet from a nozzle hole of the droplet discharge head.   An image forming apparatus comprising the liquid cartridge according to claim 6, wherein an image is recorded by ejecting ink droplets from a nozzle hole of a droplet ejection head of the liquid cartridge.   A micropump comprising the electrostatic actuator according to claim 1 and transporting a liquid by deforming a diaphragm of the electrostatic actuator with an electrostatic force.   The electrostatic actuator according to claim 1, wherein the surface of the diaphragm of the electrostatic actuator is formed by a reflecting surface, and the diaphragm is deformed by an electrostatic force to scatter incident light. An optical device characterized in that

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