JP4075545B2 - Microfluidic drive device and manufacturing method thereof, electrostatic head device and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microfluidic driving device for driving a microfluid such as a minute amount of liquid or gas, and a manufacturing method thereof, and an electrostatic head device using the microfluidic driving device and a manufacturing method thereof.
[0002]
[Prior art]
2. Description of the Related Art Inkjet printer heads that eject fine volumes of ink are widely used as printers that meet the need to print photographic quality printed matter at high speed. In the future, in order to respond to the need to print higher image quality at high speed, it is required to arrange the nozzles at a higher density without increasing the power consumption and without reducing the discharge performance.
[0003]
Conventionally, as a method of driving a micro chemical solution used for an ink jet printer head, there are a resistance heating method and a diaphragm method for a micro fluid (a micro volume of ink) held in an ink holding space (so-called cavity). The resistance heating method is a method in which a fluid in a cavity is ejected from a nozzle by a gas (bubble) generated by resistance heating. The diaphragm method is a method in which fluid is ejected from a nozzle by pressure applying means (so-called diaphragm) using a piezo element or the like.
[0004]
[Problems to be solved by the invention]
By the way, the resistance heating method can be manufactured by a semiconductor process, so the cost is low and the resistance heating element can be manufactured minutely. Therefore, it is convenient to form nozzles with high density. Therefore, power consumption increases with the number of nozzles, and it is difficult to increase the discharge frequency because the resistance heating element needs to be cooled.
In addition, the diaphragm method using the piezo effect is divided into a laminated piezo type and a single plate piezo type, and the laminated piezo type attaches the piezo actuator to the diaphragm and then separates the elements by cutting, so the semiconductor process cannot be used. High cost and difficulty in increasing density.
The single-plate piezo type can be used almost for semiconductor processes, and the cost is lower than that of the laminated type, and the power consumption is reduced. However, warping occurs due to sintering of the piezo element, and the production of a large-sized head with increased noise is produced. There are difficulties.
On the other hand, the diaphragm method using electrostatic drive consumes very little power compared to the resistance heating and piezo method.
However, these diaphragm methods consume less power than resistance heating, but because the drive distance is small, it is necessary to expand the drive area to the millimeter (mm) level length to secure the drive volume. Densification is difficult.
In addition, a conventional electrostatic drive type ink jet head is manufactured by forming a diaphragm with a Si substrate thinly etched and bonding it to a substrate such as glass on which a lower electrode is formed. In this method, it is difficult to manage the film thickness and uniformity of the diaphragm. Etching the diaphragm from the Si substrate to reduce the thickness of the Si substrate eliminates most of the thickness of the Si substrate. In order to drive, it is necessary to secure a long short side of the diaphragm, and it is difficult to increase the density. In addition, it is necessary to smooth the bonding surface with high accuracy in order to bond the substrates together, and to secure a bonding area for bonding. Absent. Furthermore, there is a problem that handling of a substrate having a thickness of about 0.1 to 0.2 mm is not easy.
[0005]
Such a problem can also occur in a driving apparatus that handles, for example, a minute gas as a minute fluid.
[0006]
In view of the above points, the present invention makes it possible to manage the thickness of the diaphragm by making it possible to manufacture in the semiconductor manufacturing process, eliminates the need for bonding of the substrates, and enables the drive unit to have a high density. The present invention provides an electrostatic microfluidic drive device that achieves high fluid drive force and improved productivity, and a method of manufacturing the same.
The present invention provides an electrostatic head device to which the above microfluidic drive device is applied and a method for manufacturing the same.
[0007]
[Means for Solving the Problems]
  The microfluidic drive device according to the present invention isA microfluidic drive device configured by a thin film in which a substrate side electrode, a support column, a diaphragm side electrode and a diaphragm are sequentially formed on a substrate,Apply pressure change to fluidA plurality of said arranged in parallelA diaphragm,eachFor driving the diaphragmMultiple independent corresponding to each diaphragmDiaphragm side electrode andCommon to each diaphragmA substrate side electrode, and the support column for forming a space between the diaphragm side electrode and the substrate side electrode,The diaphragm-side electrode is formed on the lower surface of the diaphragm, and the spaces under adjacent diaphragms communicate with each other. The diaphragm sandwiches the first insulating film having a tensile stress and the first insulating film. And a second insulating film having a compressive stress provided on both the front and back surfaces.
[0008]
In the microfluidic drive device of the present invention, when a voltage is applied between the diaphragm side electrode and the substrate side electrode, an electrostatic adsorption force is generated, and the diaphragm integrated with the diaphragm side electrode is bent. When the voltage application between the substrate-side electrodes is released, the diaphragm is released from the electrostatic force and damped and vibrated by its own restoring force. The micro fluid can be driven by using the driving of the diaphragm. Since this microfluidic drive device can be manufactured by a semiconductor process, it is easy to reduce the thickness of the diaphragm and make the film thickness uniform, thereby enabling high density. Further, since the bonding of the substrates is not required, the bonding surface is also unnecessary, and the overlay accuracy of the exposure apparatus (stepper) is higher by one digit or more than the accuracy of the bonding, so that the driving unit having the vibration plate is high. Necessary and sufficient flow driving force can be obtained while further increasing the density, and power consumption is overwhelmingly less than other methods.
[0009]
  A method for manufacturing a microfluidic drive device according to the present invention includes:CommonForming a patterned sacrificial layer on the substrate on which the substrate-side electrode is formed; and on the sacrificial layerMultiple arranged in parallelWith the same material as the process of forming the diaphragm side electrode,pluralOn the diaphragm side electrodeMultiple arranged in parallelForming a diaphragm and a column supporting the diaphragm at a required position continuous with the diaphragm; forming an opening outside the area of the diaphragm; selectively removing the sacrificial layer through the opening; A step of forming a space between the electrode and the diaphragm side electrode, and a step of closing the opening,The support column is formed so that the sacrificial layers under the adjacent diaphragms are continuous with each other. The diaphragm is formed of an insulating film having a compressive stress, an insulating film having a tensile stress, and an insulating film having a compressive stress sequentially. It is characterized by being formed as a film.
[0010]
In the method for manufacturing a microfluidic drive device of the present invention, a substrate-side common electrode, a sacrificial layer, a diaphragm-side individual electrode, a diaphragm made of the same material and its support are sequentially formed on the substrate, and the sacrificial layer is formed through the opening of the diaphragm. By having a series of steps for sealing the diaphragm opening after selective removal, a microfluidic drive device having a high density and a high driving force can be easily manufactured with high accuracy.
[0011]
  The electrostatic head device according to the present invention applies a pressure change to a fluid.Multiple arranged in parallelA diaphragm, andeachFor driving the diaphragmMultiple independent corresponding to each diaphragmDiaphragm side electrode andCommon to each diaphragmA pressure chamber having a substrate-side electrode and a support for forming a space between the diaphragm-side electrode and the substrate-side electrode, and having a fluid supply and a fluid discharge portion formed on each diaphragm. Consisting ofThe substrate side electrode, the support column, the diaphragm side electrode, and the diaphragm are composed of thin films sequentially formed on the substrate, the diaphragm side electrode is formed on the lower surface of the diaphragm, and the space under each adjacent diaphragm is The diaphragm is formed by a first insulating film having a tensile stress and a second insulating film having a compressive stress provided on both the front and back surfaces with the first insulating film interposed therebetween. Characterized by
[0012]
In the electrostatic head device of the present invention, by providing the microfluidic drive device, it is possible to increase the density of the fluid ejection section, and to control the fluid ejection amount with high driving force and high accuracy. Is possible.
[0013]
  A method for manufacturing an electrostatic head device according to the present invention includes:CommonForming a patterned sacrificial layer on the substrate on which the substrate-side electrode is formed; and on the sacrificial layerMultiple diaphragm-side electrodes arranged in parallelBy the same material as the process of formingpluralOn the diaphragm side electrodeMultiple arranged in parallelForming a diaphragm and a column supporting the diaphragm at a required position continuous with the diaphragm; forming an opening outside the area of the diaphragm; selectively removing the sacrificial layer through the opening; A step of forming a space between the electrode and the diaphragm-side electrode, a step of closing the opening, and a step of forming a pressure chamber having a fluid supply portion and a fluid discharge portion on each diaphragm,The struts are formed so that the sacrificial layers under each of the adjacent diaphragms are continuous with each other, and the diaphragm sequentially includes an insulating film having compressive stress, an insulating film having tensile stress, and an insulating film having compressive stress. It is characterized by forming a film.
[0014]
In the manufacturing method of the electrostatic head device of the present invention, since the diaphragm is formed by the vapor deposition method, a very thin diaphragm having a thickness of 1 μm or less can be provided. Thereby, the short side length of the diaphragm can be shortened to 60 μm or less, and the density can be increased to 300 dbi or more.
In addition, the thickness of the sacrificial layer of about 200 mm can be easily managed, and low voltage driving of 30 V or less can be easily realized. In addition, since the thickness of the diaphragm and the sacrificial layer can be easily managed, it is possible to manufacture the electrostatic head device that can accurately control the fluid discharge amount.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0016]
1 to 4 show an embodiment of a microfluidic drive device according to the present invention and an electrostatic head to which the microfluidic drive device is applied.
The electrostatic head 1 according to the present embodiment includes a microfluidic drive device 2 in which a plurality of diaphragms 12 driven (vibrated) by electrostatic force are arranged in parallel at high density, and positions corresponding to the diaphragms. The pressure chamber (so-called cavity) 22 in which the fluid 21 is respectively stored, and a discharge unit for discharging the fluid 21 to the outside, in this example, a partition wall structure 24 formed with a nozzle (because liquid is used as the fluid) 23 is provided. A fluid supply unit 25.
[0017]
As shown in FIGS. 2 to 4, the microfluidic drive device 2 includes a common substrate side electrode 7 made of a conductive material thin film on a required substrate 4, and an insulating film 8 on the surface of the substrate side electrode 7. A plurality of diaphragms 12 integrally formed with diaphragm-side electrodes 11 that are independently driven across the space 9 so as to face the substrate-side electrodes 7 are arranged in parallel. A support column 13 is formed on the substrate 4 so as to be supported by a cantilever.
[0018]
The diaphragm 12 is formed in a strip shape in the illustrated example, and a plurality of support pillars 13 are formed on both sides of the diaphragm 12 at predetermined intervals (pitch between support pillars) along the longitudinal direction. In addition, the predetermined interval (pitch between struts) is preferably 2 μm or more and 10 μm or less, and most preferably 5 μm. Adjacent diaphragms 12 are formed continuously through support pillars 13, and the support pillars 13 are also formed integrally with the same material as the diaphragm 12. Accordingly, the space 9 between the diaphragm 12 and the substrate-side electrode 7 communicates between the plurality of diaphragms 12 arranged in parallel. The entire space 9 that communicates between the diaphragms 12 is formed to be a sealed space.
[0019]
In order to introduce a gas or a liquid for etching and removing a sacrificial layer in a manufacturing process described later between the struts 13 of each diaphragm 12 and between the struts 13 along the longitudinal direction of one diaphragm 12 in this example. The opening 14 is formed. After removing the sacrificial layer, the opening 14 is closed by the required member 15. The opening should be □ 2 μm or less, and the smaller the opening, the easier it is to close. In the case of dry etching, it was confirmed that sufficient sacrificial layer etching was possible even with □ 0.5 μm.
Further, in this example, when the thin diaphragm 12 is used, an auxiliary support column (so-called post) 19 is formed at the same time as the support column (so-called anchor) 13 just below the center of the diaphragm 12 in order to increase the repulsive force of the diaphragm itself. Is done.
[0020]
As the substrate 4, a required substrate such as a substrate in which an insulating film is formed on a semiconductor substrate such as silicon (Si) or gallium arsenide (GaAs) or an insulating substrate such as a glass substrate including a quartz substrate is used. it can. In this example, a substrate 4 in which an insulating film 6 made of a silicon oxide film or the like is formed on a silicon substrate 5 is used. The substrate side electrode 7 is formed of a polycrystalline silicon film doped with impurities, a metal (e.g., a deposited film of Pt, Ti, Al, Au, Cr, Ni, etc.), an ITO (Indium Tin Oxide) film or the like. It is formed of an impurity-doped polycrystalline silicon film. Each individual diaphragm-side electrode 11 is formed of a polycrystalline silicon film doped with impurities, a metal (e.g., a deposited film of Pt, Ti, Al, Au, Cr, Ni, etc.), an ITO (Indium Tin Oxide) film, or the like. In this example, it is formed of an impurity-doped polycrystalline silicon film.
[0021]
As shown in FIG. 5 (enlarged view), the diaphragm-side electrode 11 is joined to the diaphragm 12 via the insulating film 17 and is inserted into the bent lower surface recess 12a of the diaphragm 12. It is formed. The diaphragm 12 is preferably formed of an insulating film, and in particular, a silicon nitride film (SiN film) that generates tensile stress and has a high repulsive force as the diaphragm. A silicon oxide film 18 is formed on the upper surface of the SiN film 12 serving as a vibration plate. Reference numeral 16 denotes a silicon oxide film formed on the lower surface of the diaphragm side electrode 11 and the lower surface of the SiN film 12 of the diaphragm. In this example, the diaphragm is substantially composed of the SiN film 12 and the insulating films 17 and 18.
[0022]
With respect to the microfluidic drive device 2, the partition structure 24 having the pressure chamber 22 and the nozzle 23, and thus the fluid supply so that the partition wall 24 a of the fluid supply unit 25 is formed at a position corresponding to the column 13 of the diaphragm 12. Part 25 is arranged. Although not shown, the pressure chamber 22 communicates with a fluid supply path.
[0023]
Next, the operation of the electrostatic head device 1 will be described.
In the microfluidic drive device 2, when a required voltage is applied between the substrate side electrode 7 and the diaphragm side electrode 11, electrostatic attraction is generated and the diaphragm 12 having the diaphragm side electrode 11 is moved to the substrate side electrode 7 side. (See FIG. 6A). Conversely, when the voltage application between the substrate side electrode 7 and the diaphragm side electrode 11 is released, the diaphragm 12 is released from the electrostatic force and damped and vibrated by its own restoring force (see FIG. 6B). The fluid 21 in the pressure chamber 22 is discharged from the nozzle 23 to the outside and the fluid 21 is supplied into the pressure chamber 22 by the volume fluctuation of the pressure chamber 22 due to the vertical drive of the diaphragm 12.
When the diaphragm 12 bends toward the substrate side electrode 7, when the space 9 is a closed space, air between the diaphragm 12 and the substrate side electrode 7 is compressed, so that the deflection of the diaphragm 12 is inhibited. However, since it is a support structure with the support column 13 and the auxiliary support column 19, the compressed air can be released into the space 9 below the adjacent vibration plate 12, and the vibration plate 12 can be sufficiently bent. .
[0024]
According to the microfluidic drive device 2 according to the present embodiment, the microfluid can be accurately controlled and supplied by deflecting the diaphragm 12 by electrostatic force and using the restoring force as the driving force. become. When the auxiliary column 19 is provided directly under the middle portion of the diaphragm 12, the length between the columns of the diaphragm is apparent even if the diaphragm 12 is thin or the short side width of the diaphragm 12 is increased. Since the repulsive force of the diaphragm 12 can be increased, the required driving force can be obtained.
The diaphragm 12 is supported by a plurality of pillars 13 that are integrated with the diaphragm 12 and an opening 14 for introducing an etchant for etching the sacrificial layer 31 is provided in the vicinity of the pillar 13 so that the long side is about 1 to 3 mm. In the formation of the space 9 between the diaphragm 12 having a short side of 30 to 100 μm and the substrate side electrode 7, the sacrificial layer space 9 under the diaphragm can be etched to the short side, so that the etching can be performed in a short time. At the same time, it is possible to simultaneously and accurately form the space 9 under each adjacent diaphragm 12.
Therefore, it is possible to provide a microfluidic drive device that can secure a driving force with respect to fluid and enable high density.
[0025]
By forming the lower substrate side electrode 7 as a common electrode and the upper diaphragm side electrode 11 as a plurality of independent electrodes, the lower surface of the diaphragm 12, that is, 16 can be formed flat. When the lower substrate-side electrode 7 is individually provided, a step due to the thickness of the electrode appears as a step in the diaphragm 12, so that the tensile stress of the diaphragm 12 is relieved by the step and the tensile stress is reduced. Does not work effectively.
On the other hand, the diaphragm 12 made of SiN and the Si diaphragm-side electrode 11 are disposed in close contact with each other via an insulating film in the lower surface recess formed by the step portion of the diaphragm 12. Even if the diaphragm 12 has a stepped portion, the tension of the diaphragm 12 is not absorbed by the stepped portion.
When the upper and lower relations between the diaphragm 12 made of the SiN film and the Si diaphragm side electrode 11 are switched, that is, when the diaphragm 12 made of the SiN film is formed first, and the Si diaphragm side electrode 11 is formed thereon, Although the diaphragm can be made flat, the voltage applied between the electrodes is also distributed to the SiN film with a high relative dielectric constant, so the effective voltage that acts on the space between the lower surface of the diaphragm and the upper surface of the substrate-side electrode is lowered. The electrostatic attractive force is reduced and the displacement of the diaphragm is also reduced, which is disadvantageous when aiming at low power consumption driving.
[0026]
Since the diaphragm side electrode 11 is not formed in the support column 13 and therefore is formed slightly inside the portion where the support column 13 is formed, dielectric breakdown due to the voltage applied to the diaphragm side electrode 11 can be prevented. .
[0027]
When the fluid supplied to the pressure chamber is a liquid, if the portion in contact with the liquid is a conductor, bubbles may form in the liquid from the conductor surface or the conductor surface may corrode. In this embodiment, the diaphragm side electrode Since the diaphragm 12 is on 11 and the surface of the diaphragm 12 is covered with the insulating film 18, such a problem does not occur.
Further, when the fluid is a liquid, the liquid can be smoothly introduced into the pressure chamber 22 by forming the hydrophilic insulating film 18 on the surface of the diaphragm 12. In addition, when the fluid is a gas, the diaphragm 12 is not attacked by the gas by forming the insulating film 18 resistant to the gas on the surface of the diaphragm 12.
[0028]
According to the electrostatic head device 1 according to the present embodiment, by providing the microfluidic drive device 2 described above, the fluid ejection units, in this example, the nozzles 23 can be arranged with high density and can be microscopically with high driving force. An amount of fluid can be controlled and supplied with high accuracy. The electrostatic head device 1 according to the present embodiment includes, for example, an inkjet printer head for consumer use, a polymer such as organic EL, a low molecular organic material coating device, a printed circuit board wiring printing device, a solder bump printing device, and a three-dimensional device for industrial use. As a modeling device, μTAS (Micro Total Analysis Systems), a supply head that supplies chemical liquids and other liquids with a fine unit of pl (picoliters) or less with high precision, and further supplies gas with a fine amount with high precision control. It can be applied to a supply head or the like.
[0029]
The electrostatic head device 1 includes a plurality of high pressure chambers, medium pressure chambers, and low pressure chambers as the pressure chambers 22. The pressure chambers 22 are connected to each other, and a backflow prevention valve is disposed between the pressure chambers 22. In addition, a configuration in which a fluid is allowed to flow is also included.
The electrostatic head device 1 can basically be configured by providing a valve at the discharge port to the outside of the pressure chamber 22 when gas is used as the fluid.
The microfluidic drive device 2 can be applied to a driving source for cooling a CPU of a computer, for example.
[0030]
Next, an embodiment of a method for manufacturing the microfluidic drive device 2 and the electrostatic head device 1 described above will be described with reference to FIGS. In addition, the process drawing of FIGS. 11-17 shows the cross-sectional structure on CC line of FIG.
[0031]
First, as shown in FIG. 11A, a substrate 4 in which, for example, a silicon oxide film 6 of an insulating film is formed on a required substrate, in this example, a silicon substrate 5, and a common substrate is formed on the silicon oxide film 6 of this substrate 4. The side electrode 7 is formed. In this example, the substrate-side electrode 7 is formed as an electrode having a conductivity by forming an amorphous silicon film by a CVD (chemical vapor deposition) method, doping it with impurities such as phosphorus (P), and then heat-treating it. Thereby, the substrate-side electrode 7 of polycrystalline silicon is formed.
[0032]
Next, as shown in FIG. 11B, an insulating film 8 is formed on the surface of the substrate-side electrode 7. The insulating film 8 can be formed, for example, by high pressure reduced pressure CVD or thermal oxidation at about 1000 ° C. This insulating film 8 includes a protective film for the substrate-side electrode 7, a film that is resistant to an etching solution or etching gas for a sacrificial layer, which will be described later, and a discharge prevention and vibration plate when the diaphragm and the substrate-side electrode come close. This is used for prevention of short circuit when contacting the substrate side electrode 7. As the insulating film 8, for example, SF₆, XeF₂When using etching gas by₂For example, when an etching solution using hydrofluoric acid is used, a SiN film can be used.
[0033]
Next, as shown in FIG. 11C, a sacrificial layer 31 is formed on the entire surface of the insulating film 8. In this example, a polycrystalline silicon film is deposited as the sacrificial layer 31 by the CVD method.
Next, as shown in FIG. 12D, the sacrificial layer 31 is selectively etched away at a portion where a post (so-called anchor) for supporting a diaphragm to be formed later is to be formed and a portion corresponding to the auxiliary post (so-called post). Opening 32 is formed. The etching of the sacrificial layer 31 is preferably dry etching.
[0034]
Next, as illustrated in FIG. 12E, the insulating film 16 is formed on the surface of the sacrificial layer 31. The insulating film 16 is formed of a film having resistance to the etching solution or etching gas of the sacrificial layer 31, similarly to the insulating film 8. In this example, the sacrificial layer 31 made of a polycrystalline silicon film is formed as SF.₆Gas or XeF₂Since etching is performed using gas, a silicon oxide film (SiO 2) is used as the insulating film 16.₂Film) is formed by thermal oxidation or CVD. This insulating film 16 is used for protection of the diaphragm side electrode, prevention of discharge when the diaphragm and the substrate side electrode 7 approach each other, prevention of short circuit when the diaphragm contacts the substrate side electrode 7, and the like. .
[0035]
Next, as shown in FIG. 13F, each independent diaphragm side electrode 11 is formed on the sacrificial layer 31 having the insulating film 16. In this example, the diaphragm-side electrode 11 is formed as an electrode having conductivity by forming an amorphous silicon film by a CVD (chemical vapor deposition) method, doping it with impurities such as phosphorus (P), and then heat-treating it. . Thereby, the diaphragm-side electrode 11 of polycrystalline silicon is formed. In order to prevent dielectric breakdown due to the voltage applied to the diaphragm-side electrode 11, the diaphragm-side electrode 11 is not formed in the column, and therefore is formed slightly inside the column-forming portion. Further, by forming the diaphragm-side electrode 11 as described above, the diaphragm-side electrode 11 is inserted into the lower surface recess of the diaphragm in a later process.
[0036]
Next, as shown in FIG. 13G, the surface of the diaphragm side electrode 11 is thermally oxidized to form a silicon oxide film 8SiO.₂After the film 17 is formed, the diaphragm 12 and the continuous support pillars (anchors) 13 and auxiliary support pillars (posts) 19 are formed of the same insulating film over the entire surface of the sacrificial layer 31 and in the opening 32. Further, the diaphragm 12, the support column 13, and the auxiliary support column 19 are formed of a silicon nitride film (SiN film) by a low pressure CVD method in this example. Since a tensile stress is generated in the SiN film, the repulsive force of the diaphragm 12 is increased, which is convenient.
[0037]
  Next, as shown in FIG. 14H, a required insulating film 18 is formed on the surfaces of the diaphragm 12, the support column 13, and the auxiliary support column 19 made of a silicon nitride film. As the insulating film 18, for example, when ink, chemical liquid, or other liquid is used as a fluid, a hydrophilic insulating film 18 is formed on the liquid contact surface. When gas is used as the fluid, the insulating film 18 that is resistant to the gas is formed. When etching the sacrificial layer 31, SF is used.₆Gas or XeF₂When using a gas, it is preferable to form the insulating film 18 with an oxide film (eg, a silicon oxide film) that is resistant to the etching gas. The diaphragm 12 made of silicon nitride film isInsulating film 17In order to prevent warping of the diaphragm when a laminated structure of a silicon nitride film having a tensile stress and a silicon oxide film having a compressive stress is formed. It is valid. In the laminated structure of the silicon nitride film and the silicon oxide film, due to the synergistic effect of tensile and compressive stress, the diaphragm becomes large and concave, and the displacement of the diaphragm is insufficient. This warpage can be alleviated by covering both sides of the silicon nitride film with a silicon oxide film.
[0038]
Next, as shown in FIG. 14I, an opening 14 is formed in the vicinity of the support pillar 13 so as to penetrate the insulating film 17, the diaphragm 12, and the insulating film 16 and expose the sacrificial layer 31. The opening 14 serves as a hole when the sacrificial layer 31 is removed by etching, and can be formed by anisotropic dry etching such as RIE.
[0039]
Next, as shown in FIG. 15J, an etching solution or etching gas is introduced through the opening 14, and in this example, SF is used.₆Gas or XeF₂Gas is introduced to remove the sacrificial layer 31 by etching, and a space 9 is formed between the diaphragm 12 having the diaphragm side electrode 11 integrally and the substrate side electrode 7. In this case, a plurality of openings 14 are formed along the long side of the diaphragm 12, and etching proceeds in the direction along the short side of the diaphragm 12 through the openings, so that etching can be performed in a short time. When silicon such as polycrystalline silicon is used as the sacrificial layer 31, SF is used.₆Gas or XeF₂Etching can be performed by gas. As the sacrificial layer 31, a silicon oxide film (SiO₂When the film is used, it can be removed by etching with a hydrofluoric acid etching solution. When the sacrificial layer 31 is removed with an etching solution, a drying process is performed.
[0040]
Next, as shown in FIG. 15K, the opening 14 is sealed. Sealing can be performed by metal sputtering of Al or the like, but the space 9 serving as a vibration chamber is decompressed, so that the vibration plate 12 becomes concave and is located near the column 13 or the auxiliary column 19 of the vibration plate 12. Stress is always applied. Moreover, the movable range of the diaphragm 12 becomes narrow due to the concave shape. In consideration of this point, for example, a method of filling the opening 14 by reflow after forming a boron-phosphorus-silicate glass (BPSG) film can be employed. At this time, N₂By performing in a pressurized atmosphere, the pressure in the space 9 serving as the vibration chamber can be set to a desired value. Further, the opening 14 can be closed by utilizing the viscosity of a pressurizing chamber forming member which will be described later. In this way, the microfluidic drive device 2 is manufactured.
[0041]
Next, as shown in FIG. 16, for example, a photocurable resin material layer, for example, a photosensitive epoxy resin material layer 33, is formed on the microfluidic drive device 2, and is patterned by using a lithography technique. A pressure chamber (so-called chamber) 22 for storing the fluid and a fluid supply passage (not shown) communicating with the pressure chamber 22 are formed. That is, the pressure chamber 22 is formed on the diaphragm 12, and the partition wall 24a for forming the pressure chamber 22 is formed on both sides of the diaphragm 12 on which the support column 13 is formed.
[0042]
Next, as shown in FIG. 17, a sheet-like body (so-called nozzle sheet) 34 having the nozzles 23 is joined so as to close the upper portion of each pressure chamber 22. The nozzle sheet 34 can be formed of a required material such as a metal such as nickel or stainless steel, or a Si wafer, and the nozzle sheet 34 is bonded.
Thus, the target electrostatic head device 1 is obtained.
[0043]
By adjusting the viscosity of the photocurable resin, the opening 14 of the diaphragm 12 can be sealed with the photocurable resin without metal sputtering.
[0044]
According to the manufacturing method according to the above-described embodiment, the following effects can be obtained by forming the sacrificial layer 9 and the diaphragm 12 in a gas phase. The uniformity of the distance between the electrodes and the uniformity of the film thickness of the diaphragm 12 are increased, and the variation in the operating voltage between the diaphragms 12 is reduced. The flatness of the surface of the diaphragm 12 is increased. Control of the distance between the electrodes and the film thickness of the diaphragm 12 is facilitated, and the diaphragm 12 having a desired film thickness can be easily made depending on the film formation time and temperature. Since it can be easily produced by a general semiconductor process, it is excellent in mass productivity.
Since the opening 14 is formed in the vicinity of the support column 13 and the sacrifice 31 is removed by etching through the opening 14, the space 9 between the diaphragm 12 and the substrate-side electrode 7 can be formed with high accuracy. Since a plurality of openings 14 are formed along the longitudinal direction of the diaphragm 12, the sacrificial layer 31 is etched in the short side direction of the diaphragm 12, and the etching time can be shortened.
In the present embodiment, the electrostatic head device 1 including the microfluidic drive device 2 including the diaphragm 12, the fluid pressure chamber 22, and the partition wall structure 24 having the nozzles 23 is manufactured by surface micromachining without using bonding. It becomes possible to do. Since a standard semiconductor process can be used including the step of etching and removing the sacrificial layer 31 from the opening 14 provided in the vicinity of the support column 13, the cost of the microfluidic drive device 2 or the electrostatic head device 1 can be reduced.
[0045]
The electrostatic head device 1 can also be manufactured by bonding a separately formed nozzle 23, pressure chamber 22, and partition wall structure 24 having a fluid supply channel (not shown) on the microfluidic drive device 2. .
A plurality of openings 14 can be formed in the vicinity of one column 13 as shown in FIG.
The support column 13 and the auxiliary support column 19 are a part of the material (substantially formed of the SiN film 12 and the silicon oxide films 17 and 18 in the illustrated example) constituting the diaphragm 12 (a part including the SiN film). Alternatively, it can be formed entirely.
[0046]
7 to 9 show other embodiments of the microfluidic drive device. In the present embodiment, the diaphragm 12 has a sufficient repulsive force and functions sufficiently as a diaphragm without being deformed, and the auxiliary support column 19 is omitted. Since other configurations are the same as those in FIGS. 2 to 4 described above, the same reference numerals are given to corresponding portions, and redundant description is omitted. The operation and effects of the present embodiment are the same as those of the embodiment of FIGS.
[0047]
【The invention's effect】
According to the microfluidic drive device according to the present invention, the power consumption is low and the density of the vibrating portion having the diaphragm can be increased. When the space between the diaphragm and the substrate-side electrode is a closed space, air is compressed when the diaphragm is bent, so it tries to inhibit the deflection of the diaphragm. Since the space under the plate communicates with each other, the air compressed in the adjacent space is released to facilitate the driving of the diaphragm.
When a substrate-side electrode is used in common and a plurality of independent diaphragm-side electrodes are formed to face the substrate-side electrode, the diaphragm can be formed flat and a diaphragm with high tension can be generated. In particular, by adopting a configuration in which the diaphragm side electrode is in close contact with the lower surface recess utilizing the step of the diaphragm, the tension absorption of the diaphragm at the step can be suppressed and high tension can be imparted. Since high tension can be obtained, the thickness of the diaphragm can be reduced.
[0048]
Since the diaphragm side electrode is formed slightly inside the column forming portion, it is possible to prevent dielectric breakdown due to the voltage applied to the diaphragm side electrode.
[0049]
By providing an opening communicating with the space between the two adjacent diaphragm-side electrodes, it is possible to remove the sacrificial layer for forming the space and form a highly accurate space. Since there is an opening in the vicinity of the support column, it is possible to remove the sacrificial layer for forming the space, and it is possible to form a precise space, and this opening affects the substantial diaphragm in the vicinity of the support column. Never give.
When the auxiliary column is provided immediately below the middle portion of the diaphragm, deformation of the diaphragm can be prevented, the repulsive force of the diaphragm can be increased, and the film thickness of the diaphragm can be reduced. Since the column is made of a part or all of the material constituting the diaphragm, manufacturing is facilitated.
[0050]
The structure in which the main material forming the diaphragm is sandwiched between the two layers of the insulating film enables the reduction of the warp of the diaphragm that is remarkably generated in the configuration of the main material and the single insulating film.
[0051]
According to the method of manufacturing a microfluidic drive device according to the present invention, the above-described microfluidic drive device can be manufactured easily and accurately. Since the sacrificial layer is removed by etching from the opening formed in the vicinity of the support column, the sacrificial layer can be manufactured using a standard semiconductor process. Thereby, the manufacturing cost can be reduced.
[0052]
According to the electrostatic head device of the present invention, by providing the above-described microfluidic drive device, the fluid discharge force, for example, the nozzle for liquid and the exit port for gas are made high in density. This type of electrostatic head device can be provided.
According to the method for manufacturing an electrostatic head device according to the present invention, the electrostatic head device can be manufactured easily and accurately. In addition, for example, surface micromachining that does not use bonding enables manufacturing of an electrostatic head device such as an inkjet printer head having a diaphragm, a pressure chamber, a discharge portion (nozzle, discharge port), and the like.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of an electrostatic head according to the present invention.
FIG. 2 is a plan view showing an embodiment of a microfluidic drive device according to the present invention.
3 is a cross-sectional view taken along the line AA in FIG.
4 is a cross-sectional view taken along the line BB in FIG. 2. FIG.
FIG. 5 is an enlarged cross-sectional view of a diaphragm portion according to the present embodiment. The
6A and 6B are operation explanatory views of the diaphragm according to the present embodiment.
FIG. 7 is a plan view showing another embodiment of the microfluidic drive device according to the present invention.
8 is a cross-sectional view taken along the line DD of FIG.
9 is a cross-sectional view taken along the line EE of FIG.
FIG. 10 is a perspective view of the diaphragm showing the position on the cut surface when explaining the manufacturing process of the electrostatic head device according to the present invention.
FIGS. 11A to 11C are manufacturing process diagrams (part 1) illustrating an embodiment of a method of manufacturing an electrostatic head device according to the invention. FIGS.
FIGS. 12A to 12E are manufacturing process diagrams (part 2) illustrating the embodiment of the manufacturing method of the electrostatic head device according to the invention. FIGS.
FIGS. 13A to 13G are manufacturing process diagrams (part 3) illustrating the embodiment of the manufacturing method of the electrostatic head device according to the invention. FIGS.
FIGS. 14A to 14I are manufacturing process diagrams (part 4) illustrating an embodiment of a method of manufacturing an electrostatic head device according to the invention. FIGS.
FIGS. 15A to 15K are manufacturing process diagrams (part 5) showing one embodiment of a method for manufacturing an electrostatic head device according to the invention. FIGS.
FIG. 16 is a manufacturing process diagram (No. 6) showing the embodiment of the manufacturing method of the electrostatic head device according to the invention;
FIG. 17 is a manufacturing process diagram (No. 7) showing the embodiment of the manufacturing method of the electrostatic head device according to the invention;
FIG. 18 is a plan view of a main part showing another embodiment of an opening provided in the diaphragm according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Electrostatic head apparatus, 2 ... Microfluidic drive device, 4 ... Substrate, 5 ... Semiconductor substrate, 6 ... Insulating film, 7 ... Substrate side electrode, 8 ... Insulating film, 9 ... space, 11 ... diaphragm side electrode, 12 ... diaphragm, 13 ... support, 14 ... opening, 15 ... sealing member, 16, 17, 18 ... Insulating film, 19 ... Auxiliary support, 21 ... Fluid, 22 ... Pressure chamber, 23 ... Nozzle, 24 ... Partition structure, 24a ... Partition, 25 ... Fluid supply Part

Claims (16)

A microfluidic drive device configured by a thin film in which a substrate side electrode, a support column, a diaphragm side electrode and a diaphragm are sequentially formed on a substrate,
A plurality of the diaphragms arranged in parallel to apply a pressure change to the fluid;
A common substrate side electrode with respect to a plurality of independent diaphragm-side electrode and the vibration plate corresponding to each vibrating plate for driving the respective diaphragms,
The column for forming a space between the diaphragm side electrode and the substrate side electrode;
The diaphragm side electrode is formed on the lower surface of the diaphragm,
The spaces under each of the adjacent diaphragms communicate with each other,
The diaphragm is formed of a first insulating film having a tensile stress and a second insulating film having a compressive stress provided on both the front and back surfaces of the first insulating film. Micro fluid drive device. The microfluidic drive device according to claim 1, wherein the diaphragm side electrode is arranged in close contact with a lower surface recess of the diaphragm. The column is formed of a part or all of the material constituting the diaphragm,
Microfluidic driving apparatus according to claim 1 or 2 wherein said post is characterized by comprising integrally formed with the diaphragm. The microfluidic drive device according to claim 3, wherein the diaphragm-side electrode is formed slightly inside a portion where the support column is formed. Two adjacent diaphragm-side electrodes are formed across an opening communicating with the space,
The microfluidic drive device according to claim 1, wherein the opening is closed. The microfluidic drive device according to claim 1, wherein an opening communicating with the space is formed in the vicinity of the support column, and the opening is closed. The microfluidic drive device according to claim 1, wherein an auxiliary support is provided immediately below the diaphragm. Forming a patterned sacrificial layer on a substrate on which a common substrate-side electrode is formed;
Forming a plurality of diaphragm side electrodes arranged in parallel on the sacrificial layer;
A plurality of diaphragms arranged in parallel on the plurality of diaphragm-side electrodes, and a column that supports the diaphragm at a required position continuous with the diaphragm, using the same material;
Forming an opening outside the region of the diaphragm, selectively removing the sacrificial layer through the opening, and forming a space between the substrate side electrode and the diaphragm side electrode;
Closing the opening;
The support column is formed such that the sacrificial layers under the adjacent diaphragms are continuous with each other,
The method of manufacturing a microfluidic drive device, wherein the diaphragm is formed by sequentially forming an insulating film having a compressive stress, an insulating film having a tensile stress, and an insulating film having a compressive stress . The diaphragm-side electrode is formed in close contact with the lower surface recess of the diaphragm, and is formed slightly inside the support column forming portion.
The method of manufacturing a microfluidic drive device according to claim 8. The method for manufacturing a microfluidic drive device according to claim 8, wherein the sacrificial layer is removed by introducing an etching base or liquid from the opening. A plurality of diaphragms arranged in parallel to give a pressure change to the fluid;
A common substrate side electrode with respect to a plurality of independent diaphragm-side electrode and the vibration plate corresponding to each vibrating plate for driving the respective diaphragms,
A support column for forming a space between the diaphragm side electrode and the substrate side electrode, and a pressure chamber having a fluid supply portion and a fluid discharge portion is formed on each diaphragm. ,
The substrate-side electrode, the support column, the diaphragm-side electrode, and the diaphragm are configured by a thin film sequentially formed on the substrate,
The diaphragm side electrode is formed on the lower surface of the diaphragm,
The spaces under each of the adjacent diaphragms communicate with each other,
The diaphragm is formed of a first insulating film having a tensile stress and a second insulating film having a compressive stress provided on both the front and back surfaces of the first insulating film. Electrostatic head device. The diaphragm side electrode is arranged in close contact with the recess on the lower surface of the diaphragm.
The electrostatic head device according to claim 11. The column is formed of a part or all of the material constituting the diaphragm,
The support column is formed integrally with the diaphragm.
The electrostatic head device according to claim 11, wherein the electrostatic head device is an electrostatic head device. The diaphragm side electrode is formed slightly inside the portion where the support column is formed.
The electrostatic head device according to claim 13. Forming a patterned sacrificial layer on a substrate on which a common substrate-side electrode is formed;
Forming a plurality of diaphragm side electrodes arranged in parallel on the sacrificial layer;
A plurality of diaphragms arranged in parallel on the plurality of diaphragm-side electrodes, and a column that supports the diaphragm at a required position continuous with the diaphragm, using the same material;
Forming an opening outside the region of the diaphragm, selectively removing the sacrificial layer through the opening, and forming a space between the substrate side electrode and the diaphragm side electrode;
Closing the opening;
Forming a pressure chamber having a fluid supply portion and a fluid discharge portion on each diaphragm;
The support column is formed such that the sacrificial layers under the adjacent diaphragms are continuous with each other,
The method of manufacturing an electrostatic head device, wherein the diaphragm is formed by sequentially forming an insulating film having a compressive stress, an insulating film having a tensile stress, and an insulating film having a compressive stress . The diaphragm-side electrode is formed in close contact with the lower surface recess of the diaphragm, and is formed slightly inside the support column forming portion.
The method of manufacturing an electrostatic head device according to claim 15.

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