Micro-pump and micro-pump manufacturing method

Abstract: A micropump for bidirectional fluid flow consists of two active diaphragm valves and a diaphragm pumping chamber, driven by unimorph piezoelectric actuators. The manufacture of the micropump comprises the following steps: A 0.3 µm oxide film is formed on the the silicon substrate (1). Part of the oxide film is etched away by hydrogen fluoride (HF). On the remaining part of the film, a wet etching step with tetra methyl ammonium hydroxide (TMAH) is performed. After stripping the remainders of the oxide with HF a new oxide layer (1.2 µm) is applied. The diaphragms are etched with a potassium hydride (KH) solution, thereby determining the thickness of the diaphragm. Then a glass substrate (2) having laser-cut through-holes (ø 0.6 mm) is bonded to the silicon substrate. The packings of the valve diaphragms are clamped between glass and silicon substrates by anodic bonding. Finally the piezoelectric actuators are attached to valve and pumping diaphragms. The thickness of packing and/or diaphragm can be adjusted to determine the valve strength. Additional layers (9) preventing adhesion can be coated on the glass substrate surface, thereby realising packings with higher fluid tightness.

Description: BACKGROUND OF THE INVENTION The present invention relates to a structure and manufacturing method for a micro-pump and micro-valve in medical fields and analytic fields wherein essentially required are liquid feed of the slight amount of a liquid with accuracy and miniaturization of the apparatus itself. There is one described, for example, in JP-A-5-164052 as micro-pump being applied in the analytic field and the like. This invention is structured, within a casing 26 as shown in FIG. 2, by a fixed stacked-type piezoelectric actuator bonded at its end face with a liquid suction and discharge member 21, and two stacked-type piezoelectric actuators 22 bonded at their end faces with valves 23, so that a structure is provided that liquid feed is realized through a passage pipe port 24 and a pump chamber 25 by driving the three actuators. US-A-5,277,556 discloses a micro pump comprising a substrate portion and a ceiling plate portion, having a through-hole for passing fluid. The micro pump is further comprising an intermediate wafer of silicon or other material, bonded on the substrate portion. The ceiling plate portion is located above this silicon wafer. A diaphragm for acting to force fluid out and a valve diaphragm for opening and closing a valve are formed in the wafer. The diaphragms are designed in such a way to get easily deformed by a drive portion, for example a piezoelectric element. A packing is also formed on the intermediate silicon substrate for damming of fluid. The European Patent Application EP-A-0 587 912, discloses a similar micro pump with a ceiling plate portion, a substrate portion and an intermediate wafer having a pumping diaphragm for acting to force fluid out and a valve diaphragm for opening and closing a valve. A drive portion with a piezoelectric element and a packing formed on the intermediate silicon substrate for damming of fluid are also available. In both documents there is a micro pump disclosed, comprising a pumping diaphragm and valve diaphragms formed on an intermediate silicon substrate, which is located between a ceiling plate portion and a substrate portion. The manufacturing of a micro pump comprising three different bonded layers is a very complex, complicated and expensive technique. Further it is not possible to produce really thin micro pumps by this technique because of the geometric dimensions of the three wafers in a combination with the drive portion, e.g. a piezoelectric element. Also, in the case of a micro-pump described in JP-A-5-1669, it is characterized as shown in FIG. 3 in that metal or polysilicon thin film 32 is formed on a sacrificial layer of an oxide film over a silicon substrate 31, further a metal or polysilicon check valve is structured by removing the sacrificial layer through etching, and a pump is structured by a piezoelectric element 34 provided on a glass substrate 33. Meanwhile, in the case of a device described in JP-A-5-263763, a structure is made as shown in FIG. 4 by attaching two pump-driving bimorph type piezoelectric elements 42 on and under a pump chamber 41, and mounting flow control valves 45 formed by a valve body 43 and a bimorph type piezoelectric element 44 to a suction port and a discharge port, so that the pump-driving piezoelectric elements 42 and the fluid control valve piezoelectric elements 44 can be drive-controlled by a same controller 46. In a case where an active valve is manufactured by using a stacked-type piezoelectric element as shown in FIG. 2 as its actuator, there has been a problem that the reduction in thickness was impossible due to the thickness of the stacked type piezoelectric element itself. Also, in the micro-pump having the two check valves as shown in FIG. 3, there has been a problem that liquid feed is possible in only one direction due to its liquid feed realized by using the passive check valves. Further, where using as shown in FIG. 4 the valve by directly closing the passage with the piezoelectric element bimorph type actuators, there has possessed a problem that the actuators had to be protected because fluid contacts with the actuator. Therefore it is an object in the present invention to realize a micro-pump which is realized high in tightness, capable of being made thin and high in pressure resistance and discharge efficiency, by using a unimorph actuator to obtain sufficient displacement in a diaphragm of a substrate portion and using such a structure as clamping a packing such as silicone rubber between the substrate portion and the ceiling plate portion. Furthermore, it is another object in the present invention to realize a micro-pump which is realized high in tightness, capable of being made thin and feeding liquid bi-directional, and high in pressure resistance and discharge efficiency, by using a unimorph actuator to obtain sufficient displacement in a diaphragm of a substrate portion and using an integral structure with a substrate portion or ceiling plate portion and a packing. SUMMARY OF THE INVENTION In the present invention, high tightness is realized in the valve portion by employing such a structure as clamping a packing such as silicone rubber between a diaphragm on a substrate and a ceiling plate. Furthermore, a unimorph actuator is structured having a piezoelectric element attached to the diaphragm to realize such a structure of allowing fluid to flow between the packing and the diaphragm or between the packing and the ceiling plate, realizing active micro-valves. Also, these two micro-valves and a pumping portion with the piezoelectric element and the diaphragm are connected by a passage to drive each actuator to effect liquid feed. Thus, a micro-pump is realized that is in a thin-type and high in pressure resistance and discharge efficiency, and capable of bi-directional liquid feed. Furthermore, in the present invention, an integral structure with the substrate and the packing is realized by forming the packing in the diaphragm on the substrate, realizing high tightness with the celling plate bonded. Or otherwise, an integral structure with the ceiling plate and the packing is realized by forming the packing on the ceiling plate, realizing high tightness with the diaphragm on the bonded substrate. Further, a unimorph actuator is structured that is attached with the piezoelectric element for the diaphragm, realizing an active micro-valve. Also, in the similar manner a pumping portion is realized that acts to discharge liquid by the unimorph actuator having the piezoelectric element attached to the diaphragm. Also, these micro-valves and the pumping portions are connected through passages so that valve opening and closing and liquid discharge are effected by driving each actuator, thereby realizing a micro-pump that is a thin type, high in pressure resistance and discharge efficiency and capable of bi-directional liquid feed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view and FIG. 1B is a sectional view showing a structure of a micro-pump of the present invention; FIG. 2 is a sectional view showing a structure of a conventional micro-pump; FIG. 3 is a sectional view showing a structure of a conventional micro-pump; FIG. 4 is a sectional view showing a structure of a conventional micro-pump; FIG. 5 is a sectional view showing a micro-pump valve structure of the present invention; FIGS. 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H and 6I are sectional views showing a manufacture method for the micro-pump of the present invention; FIGs. 7A, 7B, 7C and 7D are sectional views and FIG. 7E is a plan view showing a structure and manufacture method for the micro-pump of the present invention; FIGs. 8A, 8B, 8C and 8D are sectional views and FIG. 8E is a plan view showing a structure and manufacture method for the micro-pump of the present invention; FIGs - 9A, 9B, 9C, 9D and 9E are sectional views and FIG. 9F is a plan view showing a structure and manufacture method for the micro-pump of the present invention; FIGs. 10A, 10B, 10C, 10D, 10E and 10F are sectional views and FIG. 10G is a plan view showing a structure and manufacture method for the micro-pump of the present invention; FIG. 11A is a plan view and FIGs. 11B, 11C, 11D and 11E are sectional views showing a valve structure of the micro-pump of the present invention; FIG. 12A is a plan view and FIGs. 12B, 12C, 12D and 12E are sectional views showing a valve structure of the micro-pump of the present invention; FIG. 13A is a plan view and FIG. 13B is a sectional view showing a micro-pump structure of the micro-pump of the present invention; FIG. 14 is a sectional view showing a valve structure of the micro-pump of the present invention; FIGs. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H, 15I and 15j are sectional views showing a structure and manufacture method for the micro-pump of the present invention; FIGs. 16A, 16B, 16C and 16D are sectional views showing a structure and manufacture method for the micro-pump of the present invention; FIGs. 17A, 17B, 17C and 17D are sectional views showing a structure and manufacture method for the micro-pump of the present invention; FIGs. 18A, 18B, 18C, 18D and 18E are sectional views showing a structure and manufactuce method for the micro-pump of the present invention; FIGs. 19A, 19B, 19C, 19D, L9E and 19F are sectional views showing a structure and manufacture method for the micro-pump of the present invention; FIGs. 20A, 20B, 20C and 20D are sectional views showing a structure and manufacture method for the micro-pump of the present invention; and FIGs. 21A, 21B, 21C, 21D and 21E are sectional views showing a structure and manufacture method for the micro-pump of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The micro-pump structure of the present invention is shown in FIGs. 1A and 1B. FIG. 1A is a plan view of a micro-pump, and FIG. 1B is a sectional view of the micro-pump. Two valve diaphragms 6 and one pumping diaphragm 7 are formed by etching the silicon substrate 1, and each diaphragm is attached with a piezoelectric element 3 thereby forming a unimorph actuator. The silicon substrate 1 is bonded with a glass substrate 2 having through-holes 5, and packings 4 are clamped between the valve diaphragm 6 and the glass substrate 2. By making the thickness of this packing higher than the etch depth of the diaphragm, a normally close state of the valve is realized due to the rigidity of the diaphragm and packing (FIG. 5). By downwardly deflecting the unimorph actuator in this state, a space is caused between the glass substrate and the packing or between the packing and the valve diaphragm. The flow of a fluid through this space realizes a valve open state. Also, liquid discharge is realized by upwardly deflecting the pumping diaphragm using the unimorph actuator. Liquid feed is realized by closing and opening such two micro-valves and driving the pumping diaphragms in a proper order. Embodiments of the present invention will be explained hereinbelow based on the drawings. [Embodiment 1] First, a 0.3-µm oxide film 8 is formed by thermal oxidation as in FIG. 6B on the silicon substrate 1 as in FIG. 6A. Subsequently, the surface is patterned with resist to remove away part of the oxide film 8 by wet etching with buffer hydrogen fluoride (FIG. 6C). Then, after completely stripping off the resist, the remained thermal oxide film is used as a mask to conduct wet etching on the silicon substrate 1 by TMAH as in FIG. 6D. Subsequently, the oxide film 8 is completely stripped away by a buffer hydrogen fluoride, as in FIG. 6E. The etched portions are to be made into each diaphragm and passage of a micro-pump. Then, a 1.2-µm oxide film 8 is formed all over the surface again through thermal oxidation as in FIG. 6F. using a two-sided aligner, resist patterning is made on the back surface such that the valve diaphragm and the pumping diaphragm become a same position at the surface. Using this resist as a mask, the film 8 is patterned by buffer hydrogen fluoride (FIG. 6G). After stripping the resist, the silicon substrate 1 is etched by a potassium hydride solution as shown in FIG. 6H. By adjusting the depth of this etching, each diaphragm can be arbitrarily determined in thickness. Finally, as in FIG. 6I the oxide film 8 is completely stripped away by buffer hydrogen fluoride, completing a substrate having diaphragms. Then, although a glass substrate 2 is bonded to the silicon substrate 1 as shown in FIGs. 7A, 7B, 7C, 7D and 7E, through-holes 5 are previously formed in a diameter of 0.6 [mm] through the glass substrate 2 by excimer laser, the position of which is coincident with the position of the valve diaphragm formed in the silicon substrate (FIG. 7A). Subsequently, anodic bonding is conducted in a state that packings previously formed in valve diaphragms are clamped between the glass substrate and the silicon substrate (FIG. 7B, FIG. 7C). If a heat resistive silicone rubber is used as the packing, it is possible to sufficiently withstand in anodic bonding at approximately 300 °C and 1000V. By bonding in a state of clamping the packings in this manner, it is possible to realize a structure that the through-holes 5 are directly closed by the packings 4. At this time, by claming packings with a thickness greater than the etch depth for the valve diaphragm 6, the valve can realize a normally close state due to the rigidity of the diaphragm and packing (FIG. 5).Due to this, by arbitrarily setting the thickness of the packing or diaphragm, the valve strength can be freely adjusted against external pressure. Finally, piezoelectric elements 3 are attached to the valve diaphragm 6 and the pumping diaphragm 7 thus structuring unimorph actuators (FIG. 7D). FIG. 7E is a plan view of a completed micro-pump. Subsequently, the way to open and close the valve is explained based on FIGs. 11A, 11B, 11C, 11D and 11E. FIG. 11A is a plan view of the micro-pump. FIG. 11B and FIG. 11C show a section A-A' in FIG. 11A, and FIG. 11D and FIG. 11E show a section B-B' in FIG. 11A. The two valves are kept normally in a closed state (FIG. 11B, FIG. 11D, wherein a space is caused between the glass substrate and the packing by downwardly deflecting the unimorph actuator (FIG. 11C, FIG. 11E) enabling the fluid to pass through the through-hole. In this case, the diaphragm at its central portion displaces the most by the unimorph actuator with less displacement at a peripheral portion. Due to this, by making same the width of the packing and the width of the valve diaphragm, there is no possibility that the packing move even if the valve becomes an open state. Also, fluid discharge can be made by upwardly deflecting the pumping diaphragm through the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diaphragm and the one pumping diaphragm. Also, because of using active valves, it is also possible to replace between the suction side and the discharge side by changing the order of driving each actuator. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because the structure has the packings clamped between the glass substrate and the valve diaphragms, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 2] First, valve diaphragms 6 and a pumping diaphragm 7 are formed in a silicon substrate through the similar process to FIGs. 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H and 6I in Embodiment 1 (FIG. 8A). Subsequently, the glass substrate is formed with through-holes 5 by excimer laser, wherein the through-holes 5 are structurally positioned distant from packings 4 (FIG. 8A). Due to this, the fluid entered through the through-hole 5 is dammed off by the packing 4 clamped by the valve diaphragm and the glass substrate. Subsequently, anodic bonding is performed in a state that packings with a same width as the valve diaphragm are clamped by the glass substrate and the silicon substrate (FIG. 8C). If a heat resistive silicone rubber is used for the packing, it can be sufficiently withstand in the anodic bonding at approximately 300 °C and 1000 V. FIG. 8E represents a plan view of a micro-pump, wherein such a structure is realized that the fluid passed through the through-hole is dammed off by using a packing having the same width as the diaphragm in this manner. At this time, by clamping packings with a thickness greater than the etch depth of the valve diaphragm, a normally closed state of the valve can be realized due to rigidity of the diaphragm and packings (FIG. 5). Due to this, by setting the thickness of the packing or valve diaphragm arbitrarily, the valve strength can be freely adjusted for external pressure. Finally, piezoelectric elements 3 are attached to the valve diaphragm 6 and the pumping diaphragm 7, constituting a unimorph actuator (FIG. 8D). Subsequently, the way to open and close the valve is explained based on FIGs. 12A, 12B, 12C, 12D and 12E. FIG. 12A is a plan view of a micro-pump. FIG. 12B and FIG. 12C show a section A-A' in FIG. 12A, and FIG. 12D and FIG. 12E show a section B-B' in FIG. 12A. The two valves are kept normally in a closed state (FIG. 12B, FIG. 12D), wherein a space is caused between the glass substrate and the packing and between the valve diaphragm and the packing by downwardly deflecting the unimorph actuator (FIG. 12C, FIG. 12D) enabling the fluid to pass through the through-hole. In this case, the diaphragm at its central portion displaces the most by the unimorph actuator with less displacement at a peripheral portion. Due to this, by making same the width of the packing and the width of the valve diaphragm, there is no possibility that the packing move even if the valve becomes an open state. Also, fluid discharge can be made by upwardly deflecting the pumping diaphragm through the unimorph actuator. Liquid feed of the micro-pump is realised by driving in a proper order the two valve diaphragm and the one pumping diaphragm. Also, because of using active valves, it is also possible to replace between the suction side and the discharge side by changing the order of driving each actuator. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because the structure has the packings clamped between the glass substrate and the valve diaphragms, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 3] First, valve diaphragms 6 and a pumping diaphragm 7 are formed in a silicon substrate through the similar process to FIGs. 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H and 6I in Embodiment 1. Subsequently, as shown in FIG. 9A adhesion preventive layers 9 are coated on the glass substrate 2 and the valve diaphragms 6. At this time, it is possible to prevent against adhesion with a silicone rubber or the like in curing by using adhesion preventive layers of fluorocarbon resin or the like. In this state the glass substrate 2 is formed by through-holes 5 through which fluid pass, using excimer laser. The through-holes 5 are formed at the same portions of the adhesion preventive layers 9 (FIG. 9B). Also, the position of the through-hole is also coincident with the valve diaphragm 6 in the silicon substrate. The glass substrate 2 and silicon substrate 1 thus formed are bonded by anodic bonding as in FIG. 9C. Subsequently, a low viscous silicone rubber before setting is filled inside the diaphragm through the through-hole 5 and thereafter allowed to set, thus realizing packings 4 with high tightness (FIG. 9D). Because the glass substrate 2 and the valve diaphragm 6 are previously coated with the adhesion preventive layers 9, the packing after setting will not adhere to each side. As a result, such a structure is realized that the packing is clamped by the glass substrate and the valve diaphragm. Finally, piezoelectric elements 3 are attached to the valve diaphragms 6 and the pumping diaphragm 7 thereby constituting a unimorph actuators (FIG. 9E). FIG. 9F is a plan view of a completed micro-pump. Subsequently, the way to open and close the valve is explained based on FIGs. 11A, 11B, 11C, 11D and 11E. FIG. 11A is a plan view of a micro-pump. FIG. 11B and FIG. 11C show a section A-A' in FIG. 11A, and FIG. 11D and FIG. 11E show a section B-B' in FIG. 11A. The two valves are kept normally in a closed state (FIG. 11B, FIG. 11D), wherein a space is caused between the glass substrate and the packing by downwardly deflecting the unimorph actuator (FIG. 11C, FIG. 11E) enabling the fluid to pass through the through-hole. In this case, the diaphragm at its central portion displaces the most by the unimorph actuator with less displacement at a peripheral portion. Due to this, by making same the width of the packing and the width of the valve diaphragm, there is no possibility that the packing move even if the valve becomes an open state. Also, fluid discharge can be made by upwardly deflecting the pumping diaphragm through the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diagrams and the one pumping diaphragm. Also, because of using active valves, it is also possible to replace between the suction side and the discharge side by changing the order of driving each actuator. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Further, because the packing is formed by filling the silicone rubber, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 4] First, valve diaphragms and a pumping diaphragm are formed in a silicon substrate through the similar process to FIGs. 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H and 6I in Embodiment 1. Subsequently, as shown in FIG. 10A adhesion preventive layers 9 are coated on the glass substrate 2 and the valve diaphragms 6. At this time, it is possible to prevent against adhesion with a silicone rubber or the like in curing by using adhesion preventive layers of fluorocarbon resin or the like. In this state the glass substrate 2 is formed by through-holes 5, using excimer laser. The through-holes includes two kinds of one through which fluid passes and the other for filling a packing inside the diaphragm. Among them, the one for filling is formed at a same portion as the adhesion preventive layer 9 (FIG. 10B). The glass substrate 2 and silicon substrate 1 thus formed are bonded by anodic bonding as in FIG. 10C. Subsequently, a low viscous silicone rubber before setting is filled inside the diaphragm through the through-hole 5 and allowed to set, thus realizing packings 4 with high tightness (FIG. 10D). Because the glass substrate and the valve diaphragm are previously coated with the adhesion preventive layers 9, the packing after setting will not adhere to each side. As a result, a structure in which the packing is interposed between the glass substrate and the valve diaphragm can be realized. Also, filling holes are closed by a sealant 10 so that the fluid passed through the valve will not leak to the outside (FIG. 10E). This realizes such a structure that the fluid goes in and out through the remaining two through-holes and the flow is dammed off by the packing. Finally, piezoelectric elements 3 are attached to the valve diaphragms 6 and the pumping diaphragm 7 thereby constituting a unimorph actuators (FIG. 10F). FIG. 10G is a plan view of a completed micro-pump. Subsequently, the way to open and close the valve is explained based on FIGs. 12A, 12B, 12C, 12D and 12E. FIG. 12A is a plan view of a micro-pump. FIG. 12B and FIG. 12C show a section A-A' in FIG. 12A, and FIG. 12D and FIG. 12E show a section B-B' in FIG. 12A. The two valves are kept normally in a closed state (FIG. 12B, FIG. 12D), wherein a space is caused between the glass substrate and the packing and between the valve diaphragm and the packing by downwardly deflecting the unimorph actuator (FIG. 12C, FIG. 12E) enabling the fluid to pass through the through-hole. In this case, the diaphragm at its central portion displaces the most by the unimorph actuator with less displacement at a peripheral portion. Due to this, by making same the width of the packing and the width of the valve diaphragm, there is no possibility that the packing move even if the valve becomes an open state. Also, fluid discharge can be made by upwardly deflecting the pumping diaphragm through the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diagrams and the one pumping diaphragm. Also, because of using active valves, it is also possible to replace between the suction side and the discharge side by changing the order of driving each actuator. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because the packings are formed by filling the silicone rubber, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. A further structure of a micro-pump in the present invention is shown in FIGs. 13A and 13B. FIG. 13A is a plan view of a micro-pump, and FIG. 13B is a sectional view of the micro-pump. Two valve diaphragms and one pumping diaphragm are formed by etching in the silicon substrate 51, and each diaphragm is attached with a piezoelectric element 53 thereby forming a unimorph actuator. The silicon substrate 51 is bonded with a glass substrate 52 having through-holes 55, so that the valve diaphragms are structurally closed by packings 54. Also, the packing is in an integral structure with the valve diaphragm or glass substrate. By making the thickness of this packing higher than the etch depth of the diaphragm, a normally close state of the valve is realized due to rigidity of the diaphragm and packing (FIG. 14). This embodiment of the invention is explained hereinbelow based on the drawings. [Embodiment 5] First, a 0.3-µm oxide film 58 is formed by thermal oxidation as in FIG. 15B on the silicon substrate 51 as in FIG. 15A. Subsequently, the surface is patterned with resist to remove away part of the oxide film 58 by wet etching with buffer hydrogen fluoride (FIG. 15C). Then, after completely stripping off the resist, the remained thermal oxide film is used as a mask to conduct wet etching on the silicon substrate 51 by TMAH as in FIG. 15D. Subsequently, the oxide film 58 is completely stripped away by a buffer hydrogen fluoride as in FIG. 15E. The etched portions are to be made into each diaphragm and passage of a micro-pump. Then, a 1.2-µm oxide film 58 is formed all over the surface again through thermal oxidation as in FIG. 15F. Using a two-sided aligner, resist patterning is made on the back surface such that the valve diaphragm and the pumping diaphragm becomes a same position as the surface. Using this resist as a mask, the oxide film 58 is patterned by buffer hydrogen fluoride (FIG. 15G). After stripping the resist completely from the surface, the silicon substrate 51 is etched by a potassium hydride solution as shown in FIG. 15H. By adjusting the depth of this etching, each diaphragm can be arbitrarily determined in thickness. Finally, as in FIG. 15I the oxide film 58 is completely stripped away by buffer hydrogen fluoride, completing a substrate having diaphragms. Subsequently, as shown in (FIG. 16A), packings of a silicon rubber or the like are formed and set for the valve diaphragms 56 of the silicon substrate 51. By doing this, an integral structure is realized that has the packings 54 and the silicon substrate 51 (FIG. 16B). Then, this silicon substrate 51 is bonded by a glass substrate 52, wherein the glass substrate 52 has through-holes 55 previously formed in a diameter of 600 [µm] by excimer laser at positions coincident with the packing formed in the valve diaphragm. Due to this, if anodic bonding is realized at 300 °C and 1000 V, a structure is realized that the through-holes 55 are directly closed by the packings 54 (FIG. 16C). At this time, by providing a structure that the packing 54 is higher than the etch depth of the valve diaphragm 56, the valve becomes normally close state due to the rigidity of the diaphragm and packing (FIG. 14). This strength can be arbitrarily set by the thickness of the packing or valve diaphragm, and the valve strength for the external pressure can be freely adjusted. Finally, piezoelectric elements are attached to the valve diaphragm 56 and the pumping diaphragm 57, thus structuring unimorph actuators (FIG. 16D). The two valves are kept normally in a closed state, wherein a space is caused between the glass substrate and the packing by downwardly deflecting the unimorph actuator enabling a valve open state. Also, fluid discharge can be made by upwardly deflecting the pumping diaphragm through the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diaphragms and the one pumping diaphragm. Also, because of using active valves, it is also possible to feed liquid in an arbitrary direction by changing the drive order to each actuator. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because the valve diaphragm is partly filled by the packing, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 6] First, valve diaphragms 56 and a pumping diaphragm 57 are formed in a silicon substrate through the similar process to FIGs. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H and 15I in Embodiment 5 (FIG. 17A). Packings 54 are formed for the valve diaphragms, realizing an integral structure with the packings 54 and the silicon substrate 51 (FIG. 17B). Subsequently, anodic bonding is performed with a glass substrate 52 having through-holes 55, wherein the through-holes 55 are positioned distant from the packings 54 to have a structure that the liquid entered through the through-hole 55 is dammed off by the packing 54 at a valve diaphragm portion (FIG. 17C). Finally, piezoelectric elements are attached to the valve diaphragm 56 and the pumping diaphragm 57, constituting a unimorph actuator (FIG. 17D). The two valves are kept normally in a closed state, wherein a space is caused between the glass substrate and the packing by downwardly deflecting the unimorph actuator realizing a valve open state. Also, fluid discharge can be made by upwardly deflecting the pumping diaphragm through the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diaphragms and the one pumping diaphragm. Also, because of using active valves, liquid feed in an arbitrary direction is possible by changing the drive order to each actuators. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because the valve diaphragm is partly filled by the packing to have such a structure as to dam off the liquid, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 7] First, valve diaphragms 56 and a pumping diaphragm 57 are formed in a silicon substrate through the similar process to FIGs. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H and 15I in Embodiment 5. Subsequently, as shown in FIG. 18A adhesion preventive layers 59 of fluorocarbon resin is coated onto a glass substrate 52 to be made into a ceiling plate section, at the same positions as the valve diaphragms. This is because to prevent silicone rubber as a packing to be made into a packing from adhering to the glass substrate upon setting. In this state, through-holes 55 for passing therethrough liquid are formed in the glass substrate 52 using excimer laser, wherein the through-hole 55 is formed at the same portion of the adhesion preventive layer 59 (FIG. 18B). Also, the position of the through-hole also coincident with the valve diaphragm 56 of the silicon substrate. The glass substrate 52 and the silicon substrate 51 are bonded through anodic bonding as in FIG. 18C. Subsequently, low viscous silicone rubber is filled within the diaphragm through the through-hole 55 and allowed to set, realizing a packing 54 with high tightness (FIG. 18D). Because the glass ceiling plate side is previously coated with the adhesion preventive layer 59 of fluorocarbon resin or the like, the packing is rendered in a state bonded only to the silicon substrate side thus realizing an integral structure with the silicon substrate and the packings. In this case, when the valve diaphragm 56 is deflected downward, a gap is caused between the glass substrate and the packing thereby realizing a valve open state. Finally, piezoelectric elements 53 are attached to the valve diaphragm 56 and the pumping diaphragm 57, constituting a unimorph actuator (FIG. 18E). The two valves have spaces caused between the glass substrate and the packings by downwardly deflecting the unimorph actuators, realizing a valve open state. Also, liquid discharge is possible by upwardly deflecting the pumping diaphragm 57 by the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diaphragms 56 and the one pumping diaphragm 57. Also, because of using active valves, liquid feed in an arbitrary direction is possible by changing the drive order to each actuators. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 8] First, valve diaphragms and a pumping diaphragm are formed in a silicon substrate through the similar process to FIGs. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H and 15I in Embodiment 5. Subsequently, as shown in FIG. 19A adhesion preventive layers 59 of fluorocarbon resin is coated onto a glass substrate 52 to be made into a ceiling plate section, at the same positions as the valve diaphragms 56. This is because to prevent silicone rubber as a packing to be made into a packing from adhering to the glass substrate upon setting. In this state, through-holes 55 are formed in the glass substrate 52 using excimer laser. The through-holes includes two kinds of one to pass through liquid and the other to fill a packing within the diaphragm. Among these, the one for filling is to be formed at the same portion as the adhesion preventive layer 59 (FIG. 19B). The glass substrate 52 and silicon substrate 51 thus formed are bonded by anodic bonding as in FIG. 19C. Subsequently, low viscous silicone rubber is filled within the diaphragm through the through-hole 55 and allowed to set, realizing a packing 54 with high tightness (FIG. 19D). Because the glass ceiling plate side is previously coated with the adhesion preventive layer 59 of fluorocarbon resin or the like, the packing is rendered in a state bonded only to the silicon substrate side thus realising an integral structure with the silicon substrate and the packings. Subsequently, the filling hole is closed by a sealant 60 not to cause fluid leak (FIG. 19E). By doing this, such a structure is realized that fluid goes in and out through the two through-holes and the flow is dammed off by the packing. In a case of the valve like this, a gap is caused between the glass substrate and the packing when the valve diaphragm 56 is deflected downward, realising a valve open state. Finally, piezoelectric elements 53 are attached to the valve diaphragm 56 and the pumping diaphragm 57, constituting a unimorph actuator (FIG. 19F). The two valves have spaces caused between the glass substrate and the packings by downwardly deflecting the unimorph actuators, realizing a valve open state. Also, liquid discharge is possible by upwardly deflecting the pumping diaphragm 57 by the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diaphragms 56 and the one pumping diaphragm 57. Also, because of using active valves, liquid feed in an arbitrary direction is possible by changing the drive order to each actuators. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because of such a structure that the valve diaphragm is partly filled to dam off fluid, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 9] First, valve diaphragms 56 and a pumping diaphragm 57 are formed in a silicon substrate through the similar process to FIGs. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H and 15I in Embodiment 5. Subsequently, as shown in FIG. 20A through-holes 55 are formed by excimer laser in a glass substrate 52 to be formed into a ceiling plate section. Packings 54 are formed onto this glass substrate 52, realizing an integral structure with the packings 54 and the glass substrate 52 (FIG. 20B). This packing 54 is positioned at the same position as the valve diaphragm 56 formed on the silicon substrate. Subsequently, anodic bond is performed for the glass substrate and the silicon substrate 51 (FIG. 20C), wherein the through-hole 55 is positioned at a position distant from the packing 54 to have a structure that the fluid entered through the through-hole is dammed off by the packing 54. In a case of the valve like this, a gap is caused between the glass substrate and the packing when the valve diaphragm 56 is deflected downward, realizing a valve open state. Also, by providing a stricture that the packing 54 is higher than the etch depth of the valve diaphragm 56, it is possible to realize a valve normally close state due to the rigidity of the diaphragm and packing. Finally, piezoelectric elements 53 are attached to the valve diaphragm 56 and the pumping diaphragm 57, constituting a unimorph actuator (FIG. 20D). The two valves have spaces caused between the silicone substrate and the packings by downwardly deflecting the unimorph actuators, realizing a valve open state. Also, liquid discharge is possible by upwardly deflecting the pumping diaphragm 57 by the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diagrams 56 and the one pumping diaphragm 57. Also, because of using active valves, liquid feed in an arbitrary direction is possible by changing the drive order to each actuators. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one if a very thin type. Because of using the active valves bi-directional liquid feed is possible. Also, because of such a structure that the valve diaphragm is partly filed to dam off fluid, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. [Embodiment 10] First, valve diaphragms and a pumping diaphragm are formed in a silicon substrate through the similar process to FIGs. 15A, 15B, 15C, 15D, 15E, 15F, 15G, 15H and 15I in Embodiment 5. Subsequently, as shown in FIG. 21A through-holes 55 are formed by excimer laser in a glass substrate 52. The through-holes includes two kinds of one for passing through fluid and the other to filling a packing within the diaphragm. Among them, the one for filling is formed at the same portion as the valve diaphragm 56 formed in the silicone substrate. Subsequently, adhesion preventive layers 59 of fluorocarbon resin are coated onto the valve diaphragm portions of the silicon substrate 51 (FIG. 21B). This is because to prevent silicone rubber to be made into a packing from adhering to the silicon substrate upon setting. In this state, the silicon substrate 51 and the glass substrate 52 are bonded by anodic bonding as shown in FIG. 21C. Subsequently, low viscous silicone rubber is filled within the diaphragm through the through-hole 55 and allowed to set, realizing a packing 54 with high tightness (FIG. 21D). Because the valve diaphragm 56 on the silicon substrate is previously coated with the adhesion preventive layer 59 of fluorocarbon resin or the like, the packing is rendered in a state bonded only to the glass substrate side thus realizing an integral structure with the glass substrate and the packings. Due to this, fluid goes in and out through the remained two through-holes to realize a structure that the flow is dammed off by the packing. In a case of the valve like this, a gap is caused between the valve diaphragm and the packing when the valve diaphragm 56 is deflected downward, realizing a valve open state. Also, because of an integral structure with the glass substrate and the packings, there is no possibility that the fluid leaks through the filling hole. There is no necessity to especially close the filling hole with a sealant. Finally, piezoelectric elements 53 are attached to the valve diaphragm 56 and the pumping diaphragm 57, constituting a unimorph actuator (FIG. 21E). The two valves have spaces caused between the silicone substrate and the packings by downwardly deflecting the unimorph actuators, realizing a valve open state. Also, liquid discharge is possible by upwardly deflecting the pumping diaphragm 57 by the unimorph actuator. Liquid feed of the micro-pump is realized by driving in a proper order the two valve diagrams 56 and the one pumping diaphragm 57. Also, because of using active valves, liquid feed in an arbitrary direction is possible by changing the drive order to each actuators. Because the micro-pump like this uses the unimorph actuators employing a piezoelectric element, it can be made in one of a very thin type. Because of using the active valves, bi-directional liquid feed is possible. Also, because of such a structure that the valve diaphragm is partly filled to dam off fluid, it is possible to realize a micro-pump with high pressure resistance and high liquid feed efficiency. The micro-pump of the present invention can be made very thin and easily made in small because of employing a unimorph structure with a silicon diaphragm and piezoelectric elements. Also, an effect is provided to give pressure resistance and high efficiency of discharge performance by applying a structure that the packings are clamped between the glass substrate and the silicon substrate to realize micro-valves with high tightness. Also, by applying an integral structure with the glass substrate and the packings or with the silicon substrate and the packings to realize micro-valves with high tightness, an effect is provided to give pressure resistance and high efficient discharge performance.

Claims: A micro-pump comprising: a ceiling plate portion (2) having a through-hole (5) for passing fluid; a substrate portion (1); a drive portion by a unimorph actuator with a diaphragm and a piezoelectric element (3); and a packing (4) for damming off fluid in a state of being clamped between the ceiling plate portion (2) and the substrate portion (1) characterized in the substrate portion (1) having a pumping diaphragm (7) for acting to forcing fluid out and a valve diaphragm (6) for opening and closing a valve. A micro-pump according to claim 1, characterized by having a structure of clamping the packing (4) between the ceiling plate portion (2) and the valve diaphragm (6), wherein the through-hole (5) of the ceiling plate portion (2) for passing fluid is directly closed by the packing (4). A micro-pump according to claim 1 or 2, characterized by having a structure of clamping the packing (4) between the ceiling plate portion (2) and the valve diaphragm (6), wherein the through-hole (5) of the ceiling plate portion (2) for passing fluid and the packing (4) are positioned at distant portion, the fluid passed through the through-hole (5) being dammed off by the packing (4). A micro-pump according to claim 1, characterized in that the packing (54) is of an integral structure of the valve diaphragm (56). A micro-pump according to claim 4, characterized by having such a structure that the through-hole (55) of the ceiling plate (52) for passing fluid and the packing (54) in the valve diaphragm (56) of the substrate portion (51) are in a same position, wherein the through-hole (55) is directly closed by the packing (54). A micro-pump according to one of the claims claim 4, characterized by having such a structure that the through-hole of the ceiling plate (52) for passing fluid and the packing (54) in the valve diaphragm (56) of the substrate portion (51) are in different positions, wherein the fluid passed through the through-hole (55) is dammed off by the packing (54). A micro-pump according to claim 1, characterized in that the packing (54) is an integral structure of the ceiling plate portion (52) A micro-pump according to claim 7, characterized by having such a structure that the through-hole (55) of the ceiling plate portion (52) for passing fluid and the packing (54) in the ceiling plate portion are positioned at different positions, wherein the fluid passed through the through-hole (55) is dammed off by a packing (54). A method for manufacturing a micro-pump as claimed in claim 1, comprising steps of: forming the through-hole (5) for passing fluid in the ceiling plate portion (2); forming the diaphragm in the substrate portion (1); bonding the ceiling plate portion (2) and the substrate portion (1) in a state of clamping the packing (4); and forming the drive portion by the unimorph actuator with the diaphragm and the piezoelectric element (3). A method according to claim 9, characterized in that the through-hole (5) in the ceiling plate portion (2) acts for both passing fluid and charging the packing (4); further comprising steps of forming adhesion preventive layers (9) on the ceiling plate portion (2) and the valve diaphragm (6);and filling and curing the packing (4) between the ceiling plate portion (2) and the valve diaphragm (6). A method according to claim 9, further comprising the step of: forming a filling hole for filling the packing (4) in the ceiling plate portion (2);and closing the filling hole by a sealant (10). A method according to one of the claims 9 to 11, comprising the step of: forming the packing (54) in the valve diaphragm (56) in the substrate portion (51); A method according to claim 12, comprising steps of: forming an adhesion preventive layer (59) on the ceiling plate portion (52); and filling and curing the packing (54) in the valve diaphragm (56). A method according to claim 13, wherein the through-hole (55) in the ceiling plate portion (52) acts for both passing fluid and charging the packing (54). A method according to claim 13, further comprising the step of forming a filling hole for filling the packing (4) in the ceiling plate portion (2). A method according to one of the claims 9 to 11, comprising the step of: forming the packing (54) in the ceiling plate portion (52). A method according to claim 16, further comprising steps of: forming adhesion preventive layers (59) on the valve diaphragm (56); filling and curing the packing (54) in the valve diaphragm (56); and forming the drive portion by the unimorph actuator with the diaphragm and the piezoelectric element (53).

Inventors: FURUTA KAZUYOSHI, SHINOHARA JUN, FURUTA, KAZUYOSHI, SHINOHARA, JUN, Furuta, Kazuyoshi c/o Seiko Instruments Inc., Shinohara, Jun c/o Seiko Instruments Inc.
Applicants: SEIKO INSTR INC, SEIKO INSTRUMENTS INC.
Application year: 1999
Main classification: F04B43
IPC codes: F04B43