The present invention contains subject mater related to Japanese Patent Application JP2004-049131 filed in the Japanese Patent Office on Feb. 25, 2004, the entire contents of which being incorporated herein by reference.
1. Field of the Invention
The present invention relates to a fluid actuating apparatus, which can prevent a stress from concentrating on a portion between an electrode and a support post wherein the stress is caused due to deformation of a diaphragm when a voltage is applied to the electrode for vibrating the diaphragm, while securing repulsion force of the diaphragm, and a method for manufacturing the fluid actuating apparatus, and an electrostatically-actuated fluid discharge apparatus using the fluid actuating apparatus and a method for manufacturing the electrostatically-actuated fluid discharge apparatus.
2. Description of Related Art
In a printer which meets the demands of printing images having quality as high as photography at high speed and with high resolution, an ink-jet printer head for discharging an ink in a very small volume at a level of pl (picolitter) is widely used. For meeting the demands of printing higher-quality images at high speed and with high resolution, it is desired that nozzles are arranged with higher density in future without increasing the power consumption and without sacrificing the discharge performance.
Conventionally, the method for actuating a chemical agent in a very small volume employed in the ink-jet printer head includes, in respect of a fluid in a very small volume (ink in a very small volume) held in an ink holding space (so-called cavity), a resistance heating method and a diaphragm method. The resistance heating method is a method in which a fluid in a cavity is discharged through a nozzle by gas (bubbles) generated by resistance heating. The diaphragm method is a method in which a fluid is discharged through a nozzle by a pressure application means (so-called diaphragm) using a piezoelectric element or the like.
The resistance heating method can be prepared by a semiconductor process and hence the cost is low, and a resistance heating element having a very small size can be produced, and therefore nozzles with high density are advantageously formed, but the use of Joule heat generated by an electric current increases both the number of nozzles and the power consumption, and further the resistance heating element must be cooled, making it difficult to increase the discharge frequency.
On the other hand, the diaphragm method using a piezoelectric effect is classified into a laminate piezoelectric type and a single-layer piezoelectric type, and, in the laminate piezoelectric type, a piezoelectric actuator and a diaphragm are laminated together and then subjected to isolation by cutting, and therefore a semiconductor process cannot be used, and the process for fabrication is complicated, thus increasing the cost. In addition, the actuation distance is small, and hence there is a need to increase the actuation area to a length at a level of millimeter (mm) to secure the actuation capacity, thus making it difficult to increase the density. Further, there is a problem in that a change of the design is not easy.
The ink-jet head using a conventional electrostatic actuation method is prepared by forming a diaphragm from a Si substrate which is shaped to be thin by etching, and laminating together the diaphragm and a substrate of glass or the like having a lower electrode formed thereon. In this method, it is difficult to control the thickness of the diaphragm and its uniformity. In addition, the diaphragm is formed from a Si substrate by etching and hence almost all the thickness of the Si substrate is removed, and therefore the productivity is poor, and a diaphragm having a uniform thickness as small as several μm or less cannot be formed and therefore, for achieving actuation with a low voltage, the short side of the diaphragm is required to be longer, thus making it difficult to increase the density. Further, in lamination of the substrates, the joint surface is required to be smooth with high precision to secure a joint area for the lamination, and a lamination accuracy of ±several μm is needed, thus making it impossible to increase the density. Furthermore, there is a problem in that handling of a substrate having a thickness of about 0.1 to 0.2 mm is not easy.
For this reason, there is desired a fluid actuating apparatus using an electrostatic method, which is advantageous in that the diaphragm is formed by a semiconductor fabrication process and hence the thickness of the diaphragm can be easily controlled, no lamination of substrates is required, the density of the actuating portions can be increased, high fluid actuating force can be obtained, and the yield is high and a change of the design is easy, thus improving the productivity.
In the single-layer piezoelectric type, a semiconductor process can be almost always used, and the cost is low, as compared to that for the laminate type, and the power consumption can be lowered. However, warpage is caused during the sintering of the piezoelectric element, and it is difficult to prepare a large-size head having an increased number of nozzles. On the other hand, in the diaphragm method using electrostatic actuation, the power consumption is very low, as compared to that for the resistance heating method and the piezoelectric method, and high-speed actuation is possible (see, for example, patent documents 1 and 2).
[Patent document 1] Unexamined Japanese Patent Application Publication No. Hei 10-86362
[Patent document 2] Japanese Domestic Re-Publication of PCT International Patent Application No. WO99/34979
With respect to the diaphragm method using electrostatic actuation, the present inventors have proposed a fluid actuating apparatus which includes a diaphragm for providing a pressure change in fluid, a diaphragm-side electrode, formed for the diaphragm through an insulating film, for actuating the diaphragm, a substrate-side electrode formed so that it faces the diaphragm-side electrode through a space, and a support post, formed on the substrate-side electrode, for supporting the diaphragm-side electrode through the space.
In the electrostatically-actuated fluid discharge apparatus, the strength (repulsion force) of the diaphragm and the power consumption are important factors. For example, with respect to the diaphragm method using electrostatic actuation, the present inventors have proposed a fluid actuating apparatus which includes a diaphragm for providing a pressure change in fluid, a diaphragm-side electrode, formed for the diaphragm through an insulating film, for actuating the diaphragm, a substrate-side electrode formed so that it faces the diaphragm-side electrode through a space, and a support post, formed on the substrate-side electrode, for supporting the diaphragm-side electrode through the space. In this fluid actuating apparatus having a construction in which the diaphragm-side electrode separately formed has a rectangular form having such a size that the diaphragm-side electrode does not extend to the support post, when a voltage is applied, a stress due to deformation of the diaphragm concentrates on a portion between the electrode and the support post to weaken the diaphragm, leading to a problem in that there is a lack of the repulsion force.
According to an embodiment of the present invention, there is provided a fluid actuating apparatus which includes a diaphragm for providing a pressure change in fluid; a diaphragm-side electrode, formed for the diaphragm, for actuating the diaphragm; a substrate-side electrode formed so that it faces the diaphragm-side electrode; a space formed between the diaphragm-side electrode and the substrate-side electrode; and a support post, formed on the substrate-side electrode, for supporting the diaphragm-side electrode through the space, wherein the diaphragm-side electrode is formed so that it passes through the support post and extends to and covers part of the bottom of the support post.
According to another embodiment of the present invention, there is provided a fluid actuating apparatus which includes: a diaphragm for providing a pressure change in a fluid; a diaphragm-side electrode, formed for the diaphragm, for actuating the diaphragm; a substrate-side electrode formed so that it faces the diaphragm-side electrode; a space formed between the diaphragm-side electrode and the substrate-side electrode; and a support post, formed on the substrate-side electrode, for supporting the diaphragm-side electrode through the space, wherein the diaphragm-side electrode is formed so that it extends from the support post to another.
According to further another embodiment of the present invention, there is provided a method for manufacturing a fluid actuating apparatus, which method includes the steps of forming a substrate-side electrode on a substrate; forming a first insulating film on the substrate-side electrode; forming a sacrifice layer pattern for forming a space in a region above the first insulating film, excluding a support post-forming region; forming a second insulating film for covering the sacrifice layer pattern; forming a diaphragm-side electrode through the second insulating film on the upper surface of the sacrifice layer pattern, the sidewall of the sacrifice layer pattern, and part of the bottom of the support post-forming region; forming a third insulating film for covering the diaphragm-side electrode; forming, on the third insulating film, a diaphragm for providing a pressure change in fluid; and removing the sacrifice layer pattern to form a space in a region formed by removing the sacrifice layer pattern, and further forming, in the support post-forming region formed at the side portion of the space, a support post from the second insulating film, the diaphragm-side electrode, the third insulating film, and the diaphragm.
According to further another embodiment of the present invention, there is provided a method for manufacturing a fluid actuating apparatus, which method includes the steps of: forming a substrate-side electrode on a substrate; forming a first insulating film on the substrate-side electrode; forming a sacrifice layer pattern for forming a space in a region above the first insulating film, excluding a support post-forming region; forming a second insulating film for covering the sacrifice layer pattern; forming a diaphragm-side electrode through the second insulating film on the sacrifice layer pattern including a portion between the support post-forming regions; forming a third insulating film for covering the diaphragm-side electrode; forming, on the third insulating film, a diaphragm for providing a pressure change in fluid; and removing the sacrifice layer pattern to form a space in a region formed by removing the sacrifice layer pattern, and further forming, in the support post-forming region formed at the side portion of the space, a support post from the second insulating film, the third insulating film, and the diaphragm.
According to further another embodiment of the present invention, there is provided an electrostatically-actuated fluid discharge apparatus, which includes: a diaphragm for providing a pressure change in fluid; a diaphragm-side electrode, formed for the diaphragm, for actuating the diaphragm; a substrate-side electrode formed so that it faces the diaphragm-side electrode; a space formed between the diaphragm-side electrode and the substrate-side electrode; and a support post, formed on the substrate-side electrode, for supporting the diaphragm-side electrode through the space, wherein the diaphragm-side electrode is formed so that it passes through the support post and extends to and covers part of the bottom of the support post, wherein the diaphragm has formed thereon a pressure chamber having a fluid feed section and a fluid discharge section.
According to further another embodiment of the present invention, there is provided an electrostatically-actuated fluid discharge apparatus which includes: a diaphragm for providing a pressure change in fluid; a diaphragm-side electrode, formed for the diaphragm through an insulating film, for actuating the diaphragm; a substrate-side electrode formed so that it faces the diaphragm-side electrode; a space formed between the diaphragm-side electrode and the substrate-side electrode; and a support post, formed on the substrate-side electrode, for supporting the diaphragm-side electrode through the space, wherein the diaphragm-side electrode is formed so that it extends from the support post to another, wherein the diaphragm has formed thereon a pressure chamber having a fluid feed section and a fluid discharge section.
According to further another embodiment of the present invention, there is provided a method for manufacturing an electrostatically-actuated fluid discharge apparatus, which method includes the steps of: forming a substrate-side electrode on a substrate; forming a first insulating film on the substrate-side electrode; forming a sacrifice layer pattern for forming a space in a region above the first insulating film, excluding a support post-forming region; forming a second insulating film for covering the sacrifice layer pattern; forming a diaphragm-side electrode through the second insulating film on the upper surface of the sacrifice layer pattern, the sidewall of the sacrifice layer pattern, and part of the bottom of the support post-forming region; forming a third insulating film for covering the diaphragm-side electrode; forming, on the third insulating film, a diaphragm for providing a pressure change in fluid; removing the sacrifice layer pattern to form a space in a region formed by removing the sacrifice layer pattern, and further forming, in the support post-forming region formed at the side portion of the space, a support post from the second insulating film, the diaphragm-side electrode, the third insulating film, and the diaphragm; and forming, on the diaphragm through the third insulating film, a pressure chamber having a fluid feed section and a fluid discharge section.
According to further another embodiment of the present invention, there is provided a method for manufacturing an electrostatically-actuated fluid discharge apparatus, which method includes the steps of: forming a substrate-side electrode on a substrate; forming a first insulating film on the substrate-side electrode; forming a sacrifice layer pattern for forming a space in a region above the first insulating film, excluding a support post-forming region; forming a second insulating film for covering the sacrifice layer pattern; forming a diaphragm-side electrode through the second insulating film on the sacrifice layer pattern including a portion between the support post-forming regions; forming a third insulating film for covering the diaphragm-side electrode; forming, on the third insulating film, a diaphragm for providing a pressure change in fluid; removing the sacrifice layer pattern to form a space in a region formed by removing the sacrifice layer pattern, and further forming, in the support post-forming region formed at the side portion of the space, a support post from the second insulating film, the third insulating film, and the diaphragm; and forming, on the diaphragm through the third insulating film, a pressure chamber having a fluid feed section and a fluid discharge section.
In the fluid actuating apparatus according to an embodiment of the present invention, the diaphragm-side electrode is formed so that it passes through the support post and extends to and covers part of the bottom of the support post, or it extends from the support post to another, and therefore, as compared to the construction in which the diaphragm-side electrode is formed so that it covers the whole of the bottom of the support post, the amount of the charge, which does not contribute to deformation of the diaphragm and which is stored on the bottom of the support post, is small, thus suppressing a waste of the power consumption. In addition, in the construction in which the diaphragm-side electrode is formed so that it passes through the support post and extends to and covers part of the bottom of the support post, with respect to the strength of the diaphragm, there is an advantage in that the support post has a larger thickness by the thickness of the diaphragm-side electrode than that in the construction in which the diaphragm-side electrode is formed so that it does not extend to the support post, and thus the support post gets stronger.
The method for manufacturing a fluid actuating apparatus according to another embodiment of the present invention, includes the step for forming a diaphragm-side electrode through the second insulating film on the upper surface of the sacrifice layer pattern, the sidewall of the sacrifice layer pattern, and part of the bottom of the support post-forming region, and hence the diaphragm-side electrode is formed so that it passes through the support post and extends to and covers part of the bottom of the support post. Therefore, there can be produced a fluid actuating apparatus having a construction such that, as compared to the construction in which the diaphragm -side electrode is formed so that it covers the whole of the bottom of the support post, the amount of the charge, which does not contribute to deformation of the diaphragm and which is stored on the bottom of the support post, is small, thus suppressing a waste of the power consumption. In addition, with respect to the strength of the diaphragm, there is an advantage in that the fluid actuating apparatus can be produced so that the support post has a larger thickness by the thickness of the diaphragm-side electrode than that in the construction in which the diaphragm-side electrode is formed so that it does not extend to the support post, and thus the support post is stronger.
The method for manufacturing a fluid actuating apparatus according to an embodiment of the present invention includes the steps of forming a diaphragm-side electrode through the second insulating film on the sacrifice layer pattern including a portion between the support post-forming regions. Therefore, there can be produced a fluid actuating apparatus having a construction such that, as compared to the construction in which the diaphragm-side electrode is formed so that it covers the whole of the bottom of the support post, the amount of the charge, which does not contribute to deformation of the diaphragm and which is stored on the bottom of the support post, is small, thus suppressing a waste of the power consumption.
The electrostatically-actuated fluid discharge apparatus according to an embodiment of the present invention includes the fluid actuating apparatus according to an embodiment of the present invention, and therefore has not only the above-mentioned advantages obtained by the fluid actuating apparatus according to an embodiment of the present invention, but also an advantage in that there can be provided the electrostatically-actuated fluid discharge apparatus having high fluid actuating force and having an increased density of fluid discharge sections, e.g., nozzles for liquid, or discharge outlets for gas.
The method for manufacturing an electrostatically-actuated fluid discharge apparatus according to an embodiment of the present invention includes the method for manufacturing a fluid actuating apparatus according to an embodiment of the present invention, and therefore has not only the above-mentioned advantages obtained by the method for manufacturing a fluid actuating apparatus according to an embodiment of the present invention, but also an advantage in that the electrostatically-actuated fluid discharge apparatus can be produced easily with high precision. Further, there is an advantage in that the electrostatically-actuated fluid discharge apparatus, for example, an ink-jet printer head having a diaphragm, a pressure chamber, a discharge section (nozzle or discharge outlet), and the like can be produced by, e.g., surface micromachining without using lamination.
A task of reducing a waste of the power consumption to suppress the power consumption while achieving a diaphragm having satisfactory repulsion force for actuation of a fluid, and preventing the stress concentration on the diaphragm-side electrode and the support post is achieved by employing a structure in which the diaphragm-side electrode is formed so that it extends to and passes through the support post or a structure in which the diaphragm-side electrode is formed so that it extends from the support post to another without complicating the process for production.
The fluid actuating apparatus and the method for manufacturing a fluid actuating apparatus, and the electrostatically-actuated fluid discharge apparatus and the method for manufacturing an electrostatically-actuated fluid discharge apparatus according to the embodiments of the present invention can be generally applied to the uses in which liquid in a very small volume (volume with a unit of picolitter or smaller) is fed or discharged. For example, in the civil use, for example, an ink-jet printer head, and, in the commercial use, for example, a high molecular-weight or low molecular-weight organic material coating apparatus for organic EL or the like, a printing apparatus for printed wiring board, a printing apparatus for solder bump, a three-dimensional modeling apparatus, and a μTAS (micro total analysis system), the present invention can be applied to a feed head for feeding a chemical agent or another liquid with a unit as small as pl (picolitter) or less while controlling it with high accuracy and a feed head for feeding gas in a very small volume while controlling it with high accuracy. Further, the fluid actuating apparatus 10 can be applied to an actuator of, for example, a fluid pump for use in cooling a central processing unit (CPU) in a computer.
Further features of the invention, and the advantages offered thereby, are explained in detail hereinafter, in reference to specific embodiments of the invention illustrated in the accompanying drawings.
The fluid actuating apparatus according to the first embodiment of the present invention will be described with reference to
As shown in
On the second insulating film 14 is formed a diaphragm-side electrode 15 which is independently actuated with respect to the space 31 through the second insulating film 14. The diaphragm-side electrode 15 is rectangular (square or rectangular) as viewed from the top (as viewed from the top of the plan view of the layout) and, in the support post-forming region, the diaphragm-side electrode is formed along the sidewall of the comb teeth-like form support post 21 formed along the sidewall of the space, and may be formed so that it extends to and covers part of the bottom of the support post 21, but it is not preferred that the diaphragm-side electrode is formed so as to cover the whole of the bottom of the support post 21 since an increase of the electrostatic capacity is caused to increase the power consumption. Thus, the diaphragm-side electrode 15 is basically a rectangular electrode, and formed so that it extends into the comb teeth-like form support post formed along the side portion of the space 31. For preventing the occurrence of leakage between the adjacent diaphragm-side electrodes 15, the diaphragm-side electrodes 15 are formed independently of each other.
A third insulating film 16 for covering the diaphragm-side electrode 15 is formed on the second insulating film 14. Further, on the third insulating film 16, a plurality of diaphragms 17 for providing a pressure change in fluid, integrally having the diaphragm-side electrode 15 actuated independently, are arranged in a line, and the support post 21 is formed on the substrate 11, substantially on the first insulating film 13 in such a way that the support post supports the individual diaphragms 17 on both sides by a beam. Further, a fourth insulating film 18 is formed on the third insulating film 16 so as to cover the diaphragm 17. The third insulating film 16 is formed for the purpose of relaxing the stress applied to the diaphragm-side electrode 15 by the diaphragm 17, and, when the stress relaxation is not required, it can be omitted. As described above, in the support post-forming region which is formed so that it intrudes into the side portion of the space 31 and has a comb teeth-like form, the support post 21 is formed from the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
The diaphragm 17 formed in the example shown in the figures has a strip form, and a plurality of support posts 21 are formed along the side portion of the diaphragm 17 at predetermined intervals (pitch between the support posts). The predetermined interval (pitch between the support posts) is preferably 2 to 10 μm, most preferably 5 μm. The adjacent diaphragms 17 are formed continuously through the support post 21, and the support post 21 including the diaphragm 17 is formed. Therefore, the space 31 defined by the diaphragm 17 and the substrate-side electrode 12 forms a hollow portion between a plurality of diaphragms 17 arranged in a line. The space 31 forming a hollow portion between the diaphragms 17 is formed so that it is an enclosed space as a whole.
Near the support post 21 of each diaphragm 17, in the present Example, between the support posts 21 along the side portion of the single diaphragm 17, an opening section (not shown) for introducing gas or liquid used for removing a sacrifice layer by etching in the production process described below is formed. After removing the sacrifice layer by etching, the opening section is sealed up by a predetermined member.
As the substrate 11, a semiconductor substrate comprised of silicon (Si), gallium arsenide (GaAs), or the like, which has an insulating film (not shown) formed thereon, can be used. Therefore, as the substrate 11, an insulating substrate, such as a glass substrate including a quartz substrate, can be used. In this case, there is no need to form an insulating film on the surface of the substrate. In the present Example, as the substrate 11, a silicon substrate having an insulating film comprised of, e.g., a silicon oxide film formed on the surface is used.
The substrate-side electrode 12 is formed from an impurity-doped polycrystalline silicon film, metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used. An n+ diffused layer electrode can be formed by a method in which a substrate-side electrode pattern is formed by selective oxidation, and then implanted with B+, P+, and B+, and a channel stopper layer is formed on the p-Well, followed by arsenic (As) implantation. Similarly, a p+ diffused layer electrode can be formed on the n-Well. In the present Example, the substrate-side electrode 12 is formed from an impurity -doped polycrystalline silicon film.
The diaphragm-side electrode 15 can be formed from a material similar to the material for the substrate-side electrode 12 by a method similar to the method for forming the substrate-side electrode 12. Specifically, the diaphragm-side electrode 15 can be formed from an impurity-doped polycrystalline silicon film, metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used. In the present Example, the diaphragm-side electrode 15 is formed from an impurity-doped polycrystalline silicon film.
The diaphragm-side electrode 15 is connected to the diaphragm 17 through the third insulating film 16, and formed so that it is inserted into the lower surface concave portion formed by the bent diaphragm 17 and extends to the side of the sidewall of the space 31. The diaphragm 17 is formed from, for example, an insulating film, especially preferably a silicon nitride film (SiN film) which generates a tension stress and high repulsion force as a diaphragm. A fourth insulating film 18 is formed on the upper surface of the diaphragm 17, and the fourth insulating film 18 is formed from, e.g., a silicon oxide film. Each of the second insulating film 14 and the third insulating film 16 can be formed from, e.g., a silicon oxide film. Therefore, in the present Example, the diaphragm is comprised of substantially the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
The fluid actuating apparatus 1 having the above construction vibrates the diaphragm 17 by applying a voltage between the substrate-side electrode 12 and the diaphragm-side electrode 15 to change a fluid on the diaphragm 17 in pressure, allowing the fluid to move.
In the fluid actuating apparatus 1 of the present invention, the diaphragm-side electrode 15 is formed so that it passes through the support post 21 and extends to and covers part of the bottom of the support post 21, and therefore, as compared to the construction in which the diaphragm-side electrode 15 is formed so that it covers the whole of the bottom of the support post 21, the amount of the charge, which does not contribute to deformation of the diaphragm 17 and which is stored on the bottom of the support post 21, is small, thus suppressing a waste of the power consumption. In addition, with respect to the strength of the diaphragm 17, there is an advantage in that the support post 21 has a larger thickness by the thickness of the diaphragm-side electrode 15 than that in the construction in which the diaphragm-side electrode 15 is formed so that it does not extend to the support post 21, and thus the support post 21 is stronger. The charge density was measured when 30 V was applied to the electrode of the fluid actuating apparatus 1 having the above construction, and the deflection was measured when a distribution load of 61 kPa was applied. As a result, the charge density was 4.4 fF, and the deflection was 13 nm. On the other hand, in the conventional construction in which the diaphragm-side electrode is formed outside of the support post, the charge density was as small as 1.7 fF, but the deflection was as very large as 186 nm, and hence the diaphragm was too soft and the repulsion force was unsatisfactory. Further, in the construction in which the diaphragm-side electrode is formed so that it extends to and covers the whole of the bottom of the support post, the charge density was as very large as 5.1 fF to cause a waste of the power consumption, but the deflection was as small as 13 nm. Thus, in the fluid actuating apparatus 1 of the present invention, small deflection could be achieved without considerably increasing the charge density.
The method for producing a fluid actuating apparatus according to the first embodiment of the present invention will be described with reference to the views of
As shown in
The substrate-side electrode 12 is formed from an impurity-doped polycrystalline silicon film, but it can be also formed from an impurity-doped metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used. An n+ diffused layer electrode can be formed by a method in which a substrate-side electrode pattern is formed by selective oxidation, and then implanted with B+, P+, and B+, and a channel stopper layer is formed on the p-Well, followed by arsenic (As) implantation. Similarly, a p+ diffused layer electrode can be formed on the n-Well.
Next, as shown in
Then, as shown in
Then, as shown in
Next, as shown in
The diaphragm-side electrode 15 is formed from an impurity-doped polycrystalline silicon film, but it can be also formed from an impurity-doped metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used.
Next, as shown in
Then, as shown in
Next, as shown in
The diaphragm 17 comprised of a silicon nitride film has a construction such that it is disposed between the third insulating film 16 and the fourth insulating film 18, and this construction is effective in preventing warpage of the diaphragm when a stacked structure of the silicon nitride film having a tension stress and the silicon oxide film having a compression stress is formed. In the stacked structure of the silicon nitride film and the silicon oxide film, the diaphragm is markedly bent downwards due to the synergetic effect of the tension stress and the compression stress, lacking in the deflection of the diaphragm. By covering the both sides of the silicon nitride film with a silicon oxide film, the warpage can be relaxed. Therefore, in the present Example, the diaphragm is comprised of substantially the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
In the support post-forming region which is formed so that it intrudes into the side portion of the sacrifice layer pattern 43 and has a comb teeth-like form, the support post 21 is formed from the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
Next, as shown in
Then, as shown in
Next, as shown in
The method for producing the fluid actuating apparatus 1 of the present invention comprises the step for forming the diaphragm-side electrode 15 through the second insulating film 14 on the upper surface of the sacrifice layer pattern 43, the sidewall of the sacrifice layer pattern 43, and part of the bottom of the support post-forming region, and hence the diaphragm-side electrode 15 is formed so that it passes through the support post 21 and extends to and covers part of the bottom of the support post 21. Therefore, there can be produced a fluid actuating apparatus having a construction such that, as compared to the construction in which the diaphragm-side electrode is formed so that it covers the whole of the bottom of the support post 21, the amount of the charge, which does not contribute to deformation of the diaphragm 17 and which is stored on the bottom of the support post 21, is small, thus suppressing a waste of the power consumption. In addition, with respect to the strength of the diaphragm 17, there is an advantage in that the fluid actuating apparatus can be produced so that the support post 21 has a larger thickness by the thickness of the diaphragm-side electrode 15 than that in the construction in which the diaphragm -side electrode is formed so that it does not extend to the support post 21, and thus the support post 21 is stronger.
Next, the electrostatically-actuated fluid discharge apparatus according to the first embodiment of the present invention will be described with reference to the diagrammatic perspective view of
First, as shown in
As shown in
Next, the operation of the electrostatically-actuated fluid discharge apparatus 2is described with reference to
As shown in
Next, the method for producing an electrostatically-actuated fluid discharge apparatus according to the first embodiment of the present invention will be described with reference to the views of
A fluid actuating apparatus 1 is produced by the process described above with reference to
Then, as shown in
The opening section 44 in the diaphragm 17 described above with reference to
In the fluid actuating apparatus 1 in the present Example, the diaphragm 17 is deflected by electrostatic force and the restoring force is used as actuating force, and therefore a fluid in a very small volume can be fed while controlling it with high precision. By forming an auxiliary support post 23 immediately under the middle of the diaphragm 17, even when the diaphragm 17 is thin or the short side width of the diaphragm 17 is long, the length of the diaphragm 17 between the support posts 21 appears to be short, so that the repulsion force of the diaphragm 17 can be increased, thus obtaining required actuating force.
By virtue of the construction in which the diaphragm 17 is supported by a plurality of support posts 21 which are integrated with the diaphragm, and the opening section 44 for introducing an etchant used for etching of the sacrifice layer pattern 43 is formed near the support post 21, with respect to the formation of the space 31 between the diaphragm 17 having a long side of about 0.5 to 3 mm and a short side of about 15 to 100 μm and the substrate-side electrode 12, the space 31 to be formed by removing the sacrifice layer pattern 43 under the diaphragm 17 can be formed by performing etching in the direction of the short side, and hence, not only can the etching be done in a short time, but also the space 31 under the adjacent diaphragm 17 can be simultaneously formed with high precision. Therefore, there can be provided the fluid actuating apparatus 1 which can secure actuating force for the fluid and achieve high density.
When the substrate-side electrode 12 on the lower side is formed as a common electrode and the diaphragm-side electrode 15 on the upper side is formed in the form of a plurality of independent electrodes, the lower surface of the diaphragm 17 can be flattened. When the substrate-side electrode 12 on the lower side is in a separate form, the step due to the thickness of the electrode appears as a step of the diaphragm 17, and hence the tension stress of the diaphragm 17 is relaxed by the step, so that the tension stress does not effectively act. On the other hand, the diaphragm 17 comprised of a silicon nitride (SiN) film and the diaphragm-side electrode 15 comprised of polycrystalline silicon (Si) are disposed so that the diaphragm-side electrode 15 closely adheres to the side of the lower surface of the diaphragm 17 formed by the step portion through the third insulating film 16, and therefore, even when the diaphragm 17 has a step portion, the tension of the diaphragm 17 is not absorbed by the step portion.
When the positions of the diaphragm 17 comprised of a silicon nitride (SiN) film and the diaphragm-side electrode 15 comprised of polycrystalline silicon (Si) are switched, that is, when the diaphragm 17 comprised of a silicon nitride film is first formed and the diaphragm-side electrode 15 comprised of polycrystalline silicon is formed on the diaphragm, the diaphragm 17 can be flattened, but the voltage between the substrate-side electrode 12 and the diaphragm-side electrode 15 is also distributed to the SiN film having a higher specific permittivity, and therefore the effective voltage applied to the space 31 between the lower surface of the diaphragm 17 and the upper surface of the substrate-side electrode 12 is lowered and thus the electrostatic attraction force is lowered, so that the deflection of the diaphragm 17 is reduced, which is disadvantageous to the actuation with low power consumption.
When the fluid 61 fed to the pressure chamber 51 is liquid and the portion in contact with the liquid is comprised of a conductor, air bubbles may be formed in the liquid 61 at the conductor surface or the conductor surface may suffer corrosion, but, in the present Example, the diaphragm 17 is disposed on the diaphragm-side electrode 15 and the surface of the diaphragm 17 is covered with the fourth insulating film 18, and hence the above problem does not occur.
When the fluid 61 is liquid, by forming on the surface of the diaphragm 17 the fourth insulating film 18 from a hydrophilic film, flowing of the liquid 61 into the pressure chamber 51 can be facilitated. On the other hand, when the fluid 61 is gas, by forming on the surface of the diaphragm 17 the fourth insulating film 18 having a resistance to the gas, the diaphragm 17 is prevented from suffering corrosion due to the gas.
In the method for producing the fluid actuating apparatus 1 in the present Example, when the sacrifice layer 41 and the diaphragm 17 are formed by vapor deposition, the following effects can be obtained. The interval between the electrodes and the thickness of the diaphragm 17 are uniform, so that the dispersion of the actuation voltage between the diaphragms 17 is reduced. The flatness of the surface of the diaphragm 17 is improved. The control of the electrode interval and the thickness of the diaphragm 17 is easy, and hence the diaphragm 17 having a desired thickness can be easily formed by controlling the time or temperature for deposition. The sacrifice layer and diaphragm can be easily formed by a general semiconductor process, which is advantageous to mass production.
The opening section 44 is formed near the support post 21 and the sacrifice layer pattern 43 is removed by etching through the opening section 44, and therefore the space 31 between the diaphragm 17 and the substrate-side electrode 12 can be formed with high precision. A plurality of opening sections 44 are formed along the longitudinal direction of the diaphragm 17, and hence etching of the sacrifice layer pattern 43 proceeds in the direction of the short side of the diaphragm 17, thus making it possible to reduce the time for the etching.
In the electrostatically-actuated fluid discharge apparatus 2 in the present Example, by virtue of having the above-described fluid actuating apparatus 1, not only can the discharge sections 53 for the fluid 61, nozzles in the present Example be arranged with high density, but also the fluid 61 in a very small volume can be fed by high actuating force while controlling it with high accuracy.
The electrostatically-actuated fluid discharge apparatus 2 involves an apparatus having a construction such that the pressure chamber 51 is comprised of a plurality of high pressure chamber, intermediate pressure chamber, and low pressure chamber and the pressure chambers 51 are connected to one another, and a back-flow valve is disposed between the pressure chambers 51 and a pressure difference is utilized to permit the fluid to flow. One example is described with reference to
As shown in
In the electrostatically-actuated fluid discharge apparatus 2, as shown in
When gas is used as a fluid, the electrostatically-actuated fluid discharge apparatus 2 can be produced so that a not shown valve is basically provided at the discharge outlet of the pressure chamber 51.
In the present invention, the electrostatically-actuated fluid discharge apparatus 2 comprising the fluid actuating apparatus 1 including the diaphragm 17, and the partition structure 54 having the pressure chamber 51 and the discharge section (e.g., nozzle) 53 for a fluid can be produced by surface micromachining without using lamination. In the step for removing by etching the sacrifice layer pattern 43 through the opening section 44 formed near the support post 21 and other steps, a generally used semiconductor process can be utilized, thus lowering the cost for the fluid actuating apparatus 1 and the electrostatically-actuated fluid discharge apparatus 2.
The electrostatically-actuated fluid discharge apparatus 2 can also be produced by stacking on the fluid actuating apparatus 1 the separately formed partition structure 54 having the discharge section (e.g., nozzle) 53, the pressure chamber 51, and a fluid feed channel (not shown). Further, for example, as shown in
Next, the fluid actuating apparatus according to the second embodiment of the present invention will be described with reference to
As shown in
On the second insulating film 14 is formed a diaphragm-side electrode 15 which is independently actuated with respect to the space 31 through the second insulating film 14. The diaphragm-side electrode 15 is rectangular (square or rectangular) as viewed from the top (as viewed from the top of the plan view of the layout), and is formed so that it extends from a support post-forming region to another. That is, the diaphragm-side electrode 15 is formed between support post-forming regions so as to have a comb teeth-like form. Thus, the diaphragm-side electrode 15 is basically a rectangular electrode, and is formed so that it extends from a support post-forming region to another and has a comb teeth-like form. For preventing the occurrence of leakage between the adjacent diaphragm-side electrodes 15, the diaphragm-side electrodes 15 are formed independently of each other.
A third insulating film 16 for covering the diaphragm-side electrode 15 is formed on the second insulating film 14. Further, on the third insulating film 16, a plurality of diaphragms 17 for providing a pressure change in fluid, integrally having the diaphragm-side electrode 15 actuated independently, are arranged in a line, and the support post 21 is formed on the substrate 11, substantially on the first insulating film 13 in such a way that the support post supports the individual diaphragms 17 on both sides by a beam. Further, a fourth insulating film 18 is formed on the third insulating film 16 so as to cover the diaphragm 17. The third insulating film 16 is formed for the purpose of relaxing the stress applied to the diaphragm-side electrode 15 by the diaphragm 17, and, when the stress relaxation is not required, it can be omitted. As described above, in the support post-forming region which is formed so that it intrudes into the side portion of the space 31 and has a comb teeth-like form, the support post 21 is formed from the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
The diaphragm 17 formed in the example shown in the figures has a strip form, and a plurality of support posts 21 are formed along the side portion of the diaphragm 17 at predetermined intervals (pitch between the support posts). The predetermined interval (pitch between the support posts) is preferably 2 to 10 μm, most preferably 5 μm. The adjacent diaphragms 17 are formed continuously through the support post 21, and the support post 21 including the diaphragm 17 is formed. Therefore, the space 31 defined by the diaphragm 17 and the substrate-side electrode 12 forms a hollow portion between a plurality of diaphragms 17 arranged in a line. The space 31 forming a hollow portion between the diaphragms 17 is formed so that it is an enclosed space as a whole.
Near the support post 21 of each diaphragm 17, in the present Example, between the support posts 21 along the side portion of the single diaphragm 17, an opening section (not shown) for introducing gas or liquid used for removing a sacrifice layer by etching in the production process described below is formed. After removing the sacrifice layer by etching, the opening section is sealed up by a predetermined member.
As the substrate 11, a semiconductor substrate comprised of silicon (Si), gallium arsenide (GaAs), or the like, which has an insulating film (not shown) formed thereon, can be used. Therefore, as the substrate 11, an insulating substrate, such as a glass substrate including a quartz substrate, can be used. In this case, there is no need to form an insulating film on the surface of the substrate. In the present Example, as the substrate 11, a silicon substrate having an insulating film comprised of, e.g., a silicon oxide film formed on the surface is used.
The substrate-side electrode 12 is formed from an impurity-doped polycrystalline silicon film, metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used. An n+ diffused layer electrode can be formed by a method in which a substrate-side electrode pattern is formed by selective oxidation, and then implanted with B+, P+, and B+, and a channel stopper layer is formed on the p-Well, followed by arsenic (As) implantation. Similarly, a p+ diffused layer electrode can be formed on the n-Well. In the present Example, the substrate-side electrode 12 is formed from an impurity-doped polycrystalline silicon film.
The diaphragm-side electrode 15 can be formed from a material similar to the material for the substrate-side electrode 12 by a method similar to the method for forming the substrate-side electrode 12. Specifically, the diaphragm-side electrode 15 can be formed from an impurity-doped polycrystalline silicon film, metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used. In the present Example, the diaphragm-side electrode 15 is formed from an impurity-doped polycrystalline silicon film.
The diaphragm-side electrode 15 is connected to the diaphragm 17 through the third insulating film 16, and formed so that it is inserted into the lower surface concave portion formed by the bent diaphragm 17 and extends to the side of the sidewall of the space 31. The diaphragm 17 is formed from, for example, an insulating film, especially preferably a silicon nitride film (SiN film) which generates a tension stress and high repulsion force as a diaphragm. A fourth insulating film 18 is formed on the upper surface of the diaphragm 17, and the fourth insulating film 18 is formed from, e.g., a silicon oxide film. Each of the second insulating film 14 and the third insulating film 16 can be formed from, e.g., a silicon oxide film. Therefore, in the present Example, the diaphragm is comprised of substantially the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
The fluid actuating apparatus 3 having the above construction vibrates the diaphragm 17 by applying a voltage between the substrate-side electrode 12 and the diaphragm-side electrode 15 to change a fluid on the diaphragm 17 in pressure, allowing the fluid to move.
In the fluid actuating apparatus 3 of the present invention, the diaphragm-side electrode 15 is formed so that it passes through the support post 21 and extends to and covers part of the bottom of the support post 21, and therefore, as compared to the construction in which the diaphragm-side electrode 15 is formed so that it covers the whole of the bottom of the support post 21, the amount of the charge, which does not contribute to deformation of the diaphragm 17 and which is stored on the bottom of the support post 21, is small, thus suppressing a waste of the power consumption. In addition, there is an advantage in that the strength of the diaphragm 17 is larger than that in the construction in which the diaphragm-side electrode is formed so that it does not extend to the support post 21. Further, the charge density was measured when 30 V was applied to the electrode of the fluid actuating apparatus 3 having the above construction, and the deflection was measured when a distribution load of 61 kPa was applied. As a result, the charge density was 2.7 fF, and the deflection was 88 nm. On the other hand, in a conventional structure such that the diaphragm-side electrode was not formed in the support post, the charge density was as small as 1.7 fF, but the deflection was as very large as 186 nm, and hence the diaphragm was in contact with the surface beneath the diaphragm when the diaphragm was vibrated, so that the vibration did not smoothly proceed. Thus, in the fluid actuating apparatus 3 of the present invention, small deflection could be achieved without considerably increasing the charge density.
The method for producing a fluid actuating apparatus according to the second embodiment of the present invention will be described with reference to the views of FIGS. 21 to 31 showing the steps in the production process. The views of FIGS. 21 to 31 showing the steps in the production process mainly show cross-sectional structures at positions similar to the positions of the cross-section taken along the line A-A and the cross-section taken along the line B-B shown in the plan view of the layout of
As shown in
The substrate-side electrode 12 is formed from an impurity-doped polycrystalline silicon film, but it can be also formed from an impurity-doped metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used. An n+ diffused layer electrode can be formed by a method in which a substrate-side electrode pattern is formed by selective oxidation, and then implanted with B+, P+, and B+, and a channel stopper layer is formed on the p-Well, followed by arsenic (As) implantation. Similarly, a p+ diffused layer electrode can be formed on the n-Well.
Next, as shown in
Then, as shown in
Then, as shown in
Next, as shown in
The diaphragm-side electrode 15 is formed from an impurity-doped polycrystalline silicon film, but it can be also formed from an impurity-doped metal film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As a method for forming the film, various film formation methods, such as an evaporation method, a vapor deposition method, and a sputtering method, can be used.
Next, as shown in
Then, as shown in
Next, as shown in
The diaphragm 17 comprised of a silicon nitride film has a construction such that it is disposed between the third insulating film 16 and the fourth insulating film 18, and this construction is effective in preventing warpage of the diaphragm when a stacked structure of the silicon nitride film having a tension stress and the silicon oxide film having a compression stress is formed. In the stacked structure of the silicon nitride film and the silicon oxide film, the diaphragm is markedly bent downwards due to the synergetic effect of the tension stress and the compression stress, lacking in the deflection of the diaphragm. By covering the both sides of the silicon nitride film with a silicon oxide film, the warpage can be relaxed. Therefore, in the present Example, the diaphragm is comprised of substantially the second insulating film 14, the diaphragm-side electrode 15, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
In the support post-forming region which is formed so that it intrudes into the side portion of the sacrifice layer pattern 43 and has a comb teeth-like form, the support post 21 is formed from the second insulating film 14, the third insulating film 16, the diaphragm 17, and the fourth insulating film 18.
Next, as shown in
Then, as shown in
Next, as shown in
The method for producing the fluid actuating apparatus 3 of the present invention comprises the step for forming the diaphragm-side electrode 15 through the second insulating film 14 on the sacrifice layer pattern 43 including a portion between the support post-forming regions, and therefore, there can be produced a fluid actuating apparatus having a construction such that, as compared to the construction in which the diaphragm-side electrode is formed so that it covers the whole of the bottom of the support post 21, the amount of the charge, which does not contribute to deformation of the diaphragm 17 and which is stored on the bottom of the support post 21, is small, thus suppressing a waste of the power consumption. In addition, there is an advantage in that the strength of the diaphragm 17 is larger than that in the construction in which the diaphragm-side electrode is formed so that it does not extend to the support post 21.
Next, the electrostatically-actuated fluid discharge apparatus according to the second embodiment of the present invention will be described with reference to the diagrammatic perspective view of
First, as shown in
As shown in
The operation of the electrostatically-actuated fluid discharge apparatus 4 is similar to the above-described operation of the electrostatically-actuated fluid discharge apparatus 2.
Next, the method for producing an electrostatically-actuated fluid discharge apparatus according to the second embodiment of the present invention will be described with reference to the views of
A fluid actuating apparatus 3 is produced by the process described above with reference to FIGS. 21 to 31, and then, as shown in
Then, as shown in
The opening section 44 in the diaphragm 17 described above with reference to
In the fluid actuating apparatus 3 in the present Example, the diaphragm 17 is deflected by electrostatic force and the restoring force is used as actuating force, and therefore a fluid in a very small volume can be fed while controlling it with high precision. By forming an auxiliary support post 23 immediately under the middle of the diaphragm 17, even when the diaphragm 17 is thin or the short side width of the diaphragm 17 is long, the length of the diaphragm 17 between the support posts 21 appears to be short, so that the repulsion force of the diaphragm 17 can be increased, thus obtaining required actuating force.
By virtue of the construction in which the diaphragm 17 is supported by a plurality of support posts 21 which are integrated with the diaphragm, and the opening section 44 for introducing an etchant used for etching of the sacrifice layer pattern 43 is formed near the support post 21, with respect to the formation of the space 31 between the diaphragm 17 having a long side of about 0.5 to 3 mm and a short side of about 15 to 100 μm and the substrate-side electrode 12, the space 31 to be formed by removing the sacrifice layer pattern 43 under the diaphragm 17 can be formed by performing etching in the direction of the short side, and hence, not only can the etching be done in a short time, but also the space 31 under the adjacent diaphragm 17 can be simultaneously formed with high precision. Therefore, there can be provided the fluid actuating apparatus 3 which can secure actuating force for the fluid and achieve high density.
When the substrate-side electrode 12 on the lower side is formed as a common electrode and the diaphragm-side electrode 15 on the upper side is formed in the form of a plurality of independent electrodes, the lower surface of the diaphragm 17 can be flattened. When the substrate-side electrode 12 on the lower side is in a separate form, the step due to the thickness of the electrode appears as a step of the diaphragm 17, and hence the tension stress of the diaphragm 17 is relaxed by the step, so that the tension stress does not effectively act. On the other hand, the diaphragm 17 comprised of a silicon nitride (SiN) film and the diaphragm-side electrode 15 comprised of polycrystalline silicon (Si) are disposed so that the diaphragm-side electrode 15 closely adheres to the side of the lower surface of the diaphragm 17 formed by the step portion through the third insulating film 16, and therefore, even when the diaphragm 17 has a step portion, the tension of the diaphragm 17 is not absorbed by the step portion.
When the positions of the diaphragm 17 comprised of a silicon nitride (SiN) film and the diaphragm-side electrode 15 comprised of polycrystalline silicon (Si) are switched, that is, when the diaphragm 17 comprised of a silicon nitride film is first formed and the diaphragm-side electrode 15 comprised of polycrystalline silicon is formed on the diaphragm, the diaphragm 17 can be flattened, but the voltage between the substrate-side electrode 12 and the diaphragm-side electrode 15 is also distributed to the SiN film having a higher specific permittivity, and therefore the effective voltage applied to the space 31 between the lower surface of the diaphragm 17 and the upper surface of the substrate-side electrode 12 is lowered and thus the electrostatic attraction force is lowered, so that the deflection of the diaphragm 17 is reduced, which is disadvantageous to the actuation with low power consumption.
When the fluid 61 fed to the pressure chamber 51 is liquid and the portion in contact with the liquid is comprised of a conductor, air bubbles may be formed in the liquid 61 at the conductor surface or the conductor surface may suffer corrosion, but, in the present Example, the diaphragm 17 is disposed on the diaphragm-side electrode 15 and the surface of the diaphragm 17 is covered with the fourth insulating film 18, and hence the above problem does not occur.
When the fluid 61 is liquid, by forming on the surface of the diaphragm 17 the fourth insulating film 18 from a hydrophilic film, flowing of the liquid 61 into the pressure chamber 51 can be facilitated. On the other hand, when the fluid 61 is gas, by forming on the surface of the diaphragm 17 the fourth insulating film 18 having a resistance to the gas, the diaphragm 17 is prevented from suffering corrosion due to the gas.
In the method for producing the fluid actuating apparatus 3 in the present Example, when the sacrifice layer 41 and the diaphragm 17 are formed by vapor deposition, the following effects can be obtained. The interval between the electrodes and the thickness of the diaphragm 17 are uniform, so that the dispersion of the actuation voltage between the diaphragms 17 is reduced. The flatness of the surface of the diaphragm 17 is improved. The control of the electrode interval and the thickness of the diaphragm 17 is easy, and hence the diaphragm 17 having a desired thickness can be easily formed by controlling the time or temperature for deposition. The sacrifice layer and diaphragm can be easily formed by a general semiconductor process, which is advantageous to mass production.
The opening section 44 is formed near the support post 21 and the sacrifice layer pattern 43 is removed by etching through the opening section 44, and therefore the space 31 between the diaphragm 17 and the substrate-side electrode 12 can be formed with high precision. A plurality of opening sections 44 are formed along the longitudinal direction of the diaphragm 17, and hence etching of the sacrifice layer pattern 43 proceeds in the direction of the short side of the diaphragm 17, thus making it possible to reduce the time for the etching.
In the electrostatically-actuated fluid discharge apparatus 4 in the present Example, by virtue of having the above-described fluid actuating apparatus 3, not only can the discharge sections 53 for the fluid 61, nozzles in the present Example be arranged with high density, but also the fluid in a very small volume can be fed by high actuating force while controlling it with high accuracy.
The electrostatically-actuated fluid discharge apparatus 4 involves an apparatus having a construction such that the pressure chamber 51 is comprised of a plurality of high pressure chamber, intermediate pressure chamber, and low pressure chamber and the pressure chambers 51 are connected to one another, and a back-flow valve is disposed between the pressure chambers 51 and a pressure difference is utilized to permit the fluid to flow. As an example, there can be mentioned an apparatus having a construction similar to that of the electrostatically-actuated fluid discharge apparatus 1 described above with reference to
When gas is used as a fluid, the electrostatically-actuated fluid discharge apparatus 4 can be produced so that a not shown valve is basically provided at the discharge outlet of the pressure chamber 51.
In the present invention, the electrostatically-actuated fluid discharge apparatus 4 comprising the fluid actuating apparatus 3 including the diaphragm 17, and the partition structure 54 having the pressure chamber 51 and the discharge section (e.g., nozzle) 53 for a fluid can be produced by surface micromachining without using lamination. In the step for removing by etching the sacrifice layer pattern 43 through the opening section 44 formed near the support post 21 and other steps, a generally used semiconductor process can be utilized, thus lowering the cost for the fluid actuating apparatus 3 and the electrostatically-actuated fluid discharge apparatus 4.
The electrostatically-actuated fluid discharge apparatus 4 can also be produced by stacking on the fluid actuating apparatus 3 the separately formed partition structure 54 having the discharge section (e.g., nozzle) 53, the pressure chamber 51, and a fluid feed channel (not shown). Further, for example, as described above with reference to
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
Number | Date | Country | Kind |
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P2004-049131 | Feb 2004 | JP | national |