JPH0466785A - Micropump and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a valve portion from being deformed by anisotropic etching so as to enhance the sealing property of the valve portion by forming diaphragms and vale films in such a manner as being concentrated on that side where a valve is formed, in the direction of the thickness of an Si wafer. CONSTITUTION:In manufacturing an Si base which constitutes the main body member of a micropump, an Si wafer of fare orientation (100) is polished at both sides and then washed to form a base 1 and oxide films (SiO2 film) 2 are formed over the whole surface of the base 1 through thermal oxidation. Next the oxide films 2 on both sides of the base 1 are subjected to registration patterning so that mask patterns 3d and 3c which correspond to a diaphragm and a valve film respectively are formed on one side face of the Si wafer. Then wet anisotropic etching of Si is carried out to form a diaphragm 6b and a valve film 6a. Then the oxide film 2 on the opposite side of the Si wafer is subjected to registration patterning to form a nonthrough hole 4 and also form a valve 5. Thereafter, energizing film 7 is formed on the valve 5 portion of the base and then the whole surface of the Si wafer is caused to undergo thermal oxidation to form an oxide film 2b over the whole surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for manufacturing a micropump, and in particular, its practical application in the medical and analytical fields as part of a precision fluid control device that applies micromachining technology. This paper relates to a method for manufacturing micropumps, which is highly anticipated.

[Conventional Techniques] Research on the micromachining technology described above is currently progressing as it will open up new advanced technical fields. Regarding the trend, please refer to Nikkei Electronics N.
(L480 (published August 21, 1989) p. 125
-155, which was widely disclosed to the general public in a special feature titled "Si Micromachining Technology."

Among these, regarding the micro pump, see the 13th article in the article.
An explanation including its structure is provided on pages 5 to 139. Since micropumps are capable of controlling minute and precise flow rates, their development is expected because they can be applied to medical and analytical chemistry applications.

A method for manufacturing a micromechanical device, which includes the above-mentioned micropump, is described in the second half of the above-mentioned document. That is, pages 146 to 149 of the article describe methods for processing Si (silicon) into complex three-dimensional structures (anisotropic etching, etc.) by making full use of semiconductor etching technology, and pages 150 to On page 152, there is a detailed explanation of substrate bonding techniques (such as the anodic bonding method for bonding glass and Si substrates) that create various shapes of substrates.

A Si pressure sensor is a micromechanical device that was developed early on and is now in the practical application stage, but the micropump, which is said to be the most advanced in subsequent research, is currently in the prototype stage and has yet to be put into practical use. The current situation is that there is no such thing.

Therefore, it can be said that the manufacturing method of the micropump is still in the exploration stage and there is no established method.

[Problems to be Solved by the Invention] In order to solve the above-mentioned problems, the present inventors previously proposed a patent that established a basic manufacturing method for a micropump. That is, this is because a method for manufacturing a micropump that exhibits an accurate discharge amount has been presented.

However, the diaphragm of the micropump is made of Si.
Because it is created in the center of the wafer in the thickness direction,
The amount of etching due to anisotropic etching of the valve part is large, and the shape of the valve part is easily deformed, which may reduce the sealing performance. Furthermore, the mask of the micropump must be designed in consideration of the deformation of the valve portion, which imposes restrictions on the design of the micropump, making it impossible to design a micropump with better sealing performance.

The present invention has been made to solve the above-mentioned problems, and by forming the diaphragm and the valve membrane unevenly on the side where the valve is formed in the thickness direction of the Si wafer, the anisotropy of the valve part is improved. It is an object of the present invention to provide a micropump having a structure that eliminates deformation due to etching and further improves the degree of freedom in design, and a method for manufacturing the same.

[Means for Solving the Problems] The micropump of the present invention has a structure in which a Si substrate on which a diaphragm, a flow path, a valve, and a valve membrane are formed by wet anisotropic etching is sandwiched between glass substrates. It is characterized by being unevenly formed on the side where valves are formed in the thickness direction of the Si wafer.

The manufacturing method is to form an etching mask corresponding to the diaphragm and valve membrane on one side of a (100)-oriented Si wafer, and perform wet anisotropic etching on the one side of the Si wafer to a predetermined depth. Then, an etching mask corresponding to a through hole is formed on the surface opposite to the one surface of the Si wafer, and a recess of a predetermined depth is formed on both surfaces of the Si wafer by wet anisotropic etching. Then, an etching mask corresponding to a valve is formed on the one side and the opposite side of the Si wafer, and a predetermined amount of wet anisotropic etching is performed on both sides of the Si wafer to form a desired shape. It is characterized by forming a diaphragm, a valve, a valve membrane, and a through hole.

[Example] FIG. 1 is a schematic sectional view showing an example of a method for manufacturing a Si substrate constituting a main body member of a micropump according to the present invention. The forming method and forming state of each process step will be explained in the same order as in FIG. 1(a) to FIG. 1(k).

First, in FIG. 1(a), Si with plane orientation (100)
After polishing both sides of the wafer, the wafer is cleaned to form a substrate 1 having a thickness of 280 μm. This substrate 1 is thermally oxidized as shown in FIG.
), a 1.0 μm oxide film (S102
Form a film) 2.

Next, as shown in FIG. 1(c), resist patterning is applied to the oxide film 2 on both sides, and the oxide film 2 in the patterned portion is removed by hydrofluoric acid etching. Mask patterns 3d and 3C corresponding to valve leaflets are formed.

Next, the first wet anisotropic etching of Si was performed,
Diaphragm 6b with a depth of 60 μm shown in Fig. 1(d)
, forming the valve membrane 6a. Etching was performed at 80°C using a 30% by weight aqueous solution of potassium hydroxide.

In this case, in order to accurately etch the Si wafer to a depth of 60 μI, the etching solution was kept warm in a water bath and stirred.

Next, resist patterning is performed on the oxide film 2 on the opposite side of the one side of the Si wafer, and the oxide film 2 in the patterned portion is removed by hydrofluoric acid etching, as shown in FIG. 1(e).
A mask pattern 3 corresponding to a through hole is formed as shown in FIG.

Then, a second anisotropic etching of Si is performed in the same manner as the -th anisotropic etching, and as shown in FIG.
A non-penetrating hole of μm is formed.

At this time, the diaphragm 6b and the valve membrane 6a on one side of the Si wafer each have a depth of 120 μm.

Furthermore, resist patterning was performed on the surface opposite to the one surface of the Si wafer, and the oxide film 2 in the patterned portion was removed by hydrofluoric acid etching, as shown in FIG. 1(g).
Mask patterns 3b and 3a corresponding to diaphragms and valves are formed as shown in FIG.

Then, another degree of anisotropic etching was performed, as shown in Figure 1 (h
), a diaphragm and a valve with a depth of 50 μm are formed on the surface opposite to the one surface of the Si wafer. At this time, the diaphragm 6b on one side of the Si wafer,
Each valve membrane 6a has a depth of 170 μm, and a through hole 4 is also formed.

In this way, when the diaphragm 6 is unevenly distributed in the thickness direction toward the side where the valve is formed, the anisotropic etching for forming the valve 5 is only about 50 μm, so there is no deformation or chipping of the valve 5. Improved sealing performance of the valve can be measured. Thereafter, the oxide film 2.2a is removed using a hydrofluoric acid solution to obtain the state shown in FIG. 1(i).

Next, as shown in FIG. 1(j), in order to form a biasing film 7 with a thickness of 1 μm on the valve 5 portion of the substrate in this state,
Perform mask sputtering. This is to prevent only the biasing membrane 7 of the valve 5 from being bonded to the glass in the anodic bonding step in subsequent assembly.

After this, the entire surface of the Si wafer is subjected to the aforementioned thermal oxidation, and the first
As shown in Figure (k), an oxide film 2b is applied to the entire surface with a thickness of 0.1
Form 3 μm. This entire surface thermal oxidation process is performed to make the liquid flow easier and to improve corrosion resistance when a chemical is used as the liquid. In this way, Figure 1 (k
), the formation of the Si substrate for the pump body is completed, with the biasing film 7 made of an oxide film remaining about 1 μm in the valve 5 portion.

2 and 3 are schematic cross-sectional views for explaining the method of assembling the micropump, FIG. 2 is a cross-sectional view, and FIG. 3 is a plan configuration diagram for explaining the cross-sectional location of FIG. 2. That is, FIG. 2 is a sectional view taken along the line A-A shown in FIG. 3. In addition, in FIG. 2, the Si substrate is shown with the thin oxide film 2b omitted.

As seen in the figure, the diaphragm 6, the valve 5 and the flow path 11
The Si substrate on which is formed is anodically bonded to a predetermined position using a lower glass plate 10 having an electrode surface (not shown) on the lower surface (
(Refer to the above-mentioned document) Then, the upper glass plate 9 having an electrode surface (not shown) on the upper surface is similarly bonded to form the flow path 11 and the pressure chamber 12 connected thereto. At this time, the upper glass plate 9
The lower glass plate 10 is made of borosilicate glass with a thickness of llllI21, and the lower glass plate 10 has holes that will become the liquid supply port 13 and the liquid discharge port 14, and the upper glass plate 9 has holes formed in the upper part of the diaphragm 6. Place the piezoelectric element plate 17 in the G position.
! A hole 18 is provided in advance. Note that in this case, the oxide film 2
Since b is thin at 0-13 μm, anodic bonding is possible, but
Since the biasing film 7 is an oxide film having a thickness of 1 μm, it is not anodic bonded.

Thereafter, a supply tube 15 is connected below the supply port 13, and a discharge tube 16 is connected below the discharge port 14.

Finally, a piezoelectric element plate (piezo) 17 is adhered to the upper part of the diaphragm 6, electrical wiring for driving the piezoelectric element (not shown), and piping (not shown) are provided for the supply port 15 and the discharge port 16, thereby completing the micropump.

Through the above steps, the shape of the micropump completed was as designed with little deformation, and the valve was also less deformed due to anisotropic etching.

Furthermore, when the piezoelectric element plate was actually driven by energizing it and liquid such as water was discharged from the micropump, the discharge amount was obtained almost as designed. This is because the amount of anisotropic etching on the side of the Si substrate where the flow paths, valves, and pressure chambers are located is small, so that the deformation of the flow paths, valves, pressure chambers, etc. due to etching is small and the results are close to the designed values.

Next, in the above state, the drive of the piezoelectric element plate was stopped, and a predetermined water pressure was applied from the supply port of the pump to check for water leakage (pump sealability). As a result, there was no water leakage at all. Furthermore, a predetermined water pressure was applied to the discharge port of the pump to check for water backflow, but there was no backflow at all. The hermeticity and backflow prevention properties of these micropumps are shown in Figure 1 (k
), the diaphragm 6 of the Si substrate was unevenly distributed on the side where the valve 5 was located, so the amount of anisotropic etching on the side where the valve 5 was located was reduced, and the resulting deformation or chipping of the valve 5 portion was almost eliminated.

Although one embodiment of the present invention using a piezoelectric element as the diaphragm driving means has been described above, the manufacturing method according to the present invention is not limited to the micropump having the structure of this embodiment, and the gist thereof will be explained below. It goes without saying that the invention can be applied to micropumps of other configurations and similar fluid control devices without departing from the scope.

[Effects of the Invention] As described above, according to the present invention, in particular, in the method for forming the Si substrate constituting the micropump body, the diaphragm and the valve membrane are formed unevenly on the side where the valve is formed. No deformation or chipping of diaphragms and valves due to anisotropic etching. Therefore, the structure is such that the discharge amount of the micropump is accurately regulated, and a micropump with excellent sealing performance and backflow prevention properties can be manufactured.

Furthermore, the degree of freedom in designing the micropump is increased, and there is also the effect that it is possible to design a more efficient micropump.

[Brief explanation of drawings]

FIG. 1 shows a Si micropump showing an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional process diagram illustrating a method for manufacturing a substrate. FIG. 2 is a sectional view illustrating a method of assembling a micropump formed by the manufacturing method of the present invention. FIG. 3 is a plan configuration diagram illustrating the cross-sectional area of FIG. 2. In the figure, 1 is a Si wafer, 2, 2a, 2b are oxide films, 3.3a, 3b, 3c, 3d are etching mask patterns, 4 is an unpierced hole, 4a is a through hole, 5 is a valve, 6,
6a is a diaphragm, 6b is a valve leaflet, 7 is a biasing membrane, 8 is S
i substrate, 9 is an upper glass plate, 10 is a lower glass plate, 11 is a flow path, 12 is a pressure chamber, 13 is a supply port, 14 is a discharge port, 15 is a supply tube, 16 is a discharge tube, 17 is a piezoelectric element plate It is. Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Kisanbe Meiki (and 1 other person) Figure 1 (a) Figure 1 (b) Figure 1 (c) Figure 1 (9) Figure 1 (h) Figure 1 (i) Figure 1 (d) Figure 1 (f) Figure 1 (j) Figure 1 (k)

Claims (2)

[Claims] (1) In a micropump having a structure in which a Si substrate on which a diaphragm, a flow path, a valve, and a valve membrane are formed by wet anisotropic etching is sandwiched between glass substrates, the valve is A micropump characterized in that it is formed unevenly on the side where it is formed. (2) (a) Forming an etching mask corresponding to the diaphragm and valve membrane on one side of the (100)-oriented Si wafer, (b) Wet anisotropy on the one side of the Si wafer. forming a recessed portion of a predetermined depth by etching; (c) forming an etching mask corresponding to a through hole on the one surface and the opposite surface of the Si wafer; (d) wet etching both surfaces of the Si wafer. forming a recessed portion of a predetermined depth by anisotropic etching; (e) forming an etching mask corresponding to a valve on a surface opposite to the one surface of the Si wafer; (f) both surfaces of the Si wafer; 2. The method of manufacturing a micropump according to claim 1, wherein the diaphragm, valve, valve membrane, and through hole of a desired shape are formed by performing wet anisotropic etching of a predetermined amount of the micropump.