JPH0777136A - Fluid injection nozzle and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent generation of crystal fault of a fluid injection nozzle formed in such constitution that an opening part is provided on a plurality of silicon plates, and also improve position accuracy of a space between opening parts. CONSTITUTION:A first orifice 43 and a second orifice 45 are provided on a first orifice plate part 41 and a second orifice plate part 42, SiO2 films 110, 210 are provided on surfaces opposing to respective orifice plate parts 41, 42, and the SiO2 films 110, 210 abut and being brought in contact with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid injection nozzle, and more particularly to an injection nozzle portion of an electromagnetic fuel injection valve for injecting fuel into an internal combustion engine of an automobile.

[0002]

2. Description of the Related Art As prior art, Japanese Patent Laid-Open No. 2-75757
As disclosed in the publication, there is a fuel injection valve provided with a plurality of silicon plates on the front side of the injection holes, the holes having holes for passing fuel. The fuel flow is controlled by using a silicon plate to form a spray pattern with precise fuel passage holes.

Further, as an injection nozzle of this kind, the applicant of the present invention has previously proposed in Japanese Patent Application No. 5-28106 that a rectangular nozzle is formed in the front side of the injection hole of the fuel injection valve and is tapered toward the downstream side. There is a technique in which two silicon plates provided with slits are overlapped with each other to atomize fuel spray.

[0004]

In the case of a fluid ejection nozzle constructed by stacking two silicon plates in this manner, the holes in each silicon crystal plate are used in a general semiconductor device manufacturing method or the like. Although it is formed by such etching, it is a very thin crystal plate with a thickness of several hundreds of μm. When superimposing them, if a minute foreign substance enters the interface of the superposition, crystal defects will occur centering on that part. Easily occurs, and the withstand voltage characteristic remarkably deteriorates. In addition, it is necessary to increase the adhesion between the plates at the time of mounting, and it is necessary to press the plates with a certain amount of pressure. At that time, there is a risk that the crystal may be defective and cleaved.

Further, since the holes formed in each silicon plate are formed in individual steps, the positional accuracy is deteriorated due to an assembly error when mounting on the injection valve, so that the spray atomization characteristics are significantly varied. There was a problem. Therefore, in order to solve such a problem, it is an object of the present invention to provide a fluid injection nozzle in which a plurality of silicon plates are joined and the holes in the upper and lower silicon plates are formed by etching, and a manufacturing method thereof. is there.

[0006]

In order to achieve the above-mentioned object, the present invention provides a plurality of silicon plates having openings formed by etching, and a plurality of the silicon plates on opposite surfaces thereof. With respect to the etching of the opening, a film having durability is provided, and the technical means of joining the plurality of silicon plates through the film is adopted. In addition, a film having durability against the etching of the silicon plate is formed on each of the facing surfaces of the plurality of silicon plates, the plurality of silicon plates are joined via the film, and each silicon plate is etched. When forming the openings, at least the openings etched from the surfaces to be joined may be formed after joining.

[0007]

According to the present invention, a plurality of silicon plates each having an opening formed by etching and a film having a durability against the etching of the openings are formed on the opposite surfaces of the silicon plate. Since the silicon plate is bonded through the film by means of, the particles of dust, etc. are prevented from entering and the plate is prevented from cracking, which would lower the bonding adhesion between the upper and lower silicon plates. However, it is possible to dramatically improve the yield when the plates are mass-produced. Also, after joining the upper and lower plates through a film such as an oxide film, at least for the openings that are etched from the surfaces to be joined, by forming the nozzle using the method of forming after joining, The position of the opening can be formed with high precision, and it is possible to significantly reduce the variation in spraying performance.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of the discharge portion of the fuel injection nozzle of the present invention applied to a fuel injection valve of a fuel supply device for a gasoline engine. The fuel injection valve 10 is
The valve body 11 is provided with a valve member 12 which is slidable in the axial direction. The valve member 12 is urged downward in the axial direction by an elastic member such as a compression spring (not shown), and is formed in a conical shape at the tip of the valve member. The seat portion 12a is seated on the valve seat 20 of the valve body 11. When the valve is opened, the valve member 12 moves axially upward to a predetermined position by an electromagnetic action of an electromagnetic coil or the like (not shown), and a gap is created between the seat portion 12a and the valve seat 20 to fill the outer periphery of the valve member. Fuel that had been passed through the gap,
It is ejected from the injection hole 21. When the valve is closed, the excitation of the electromagnetic coil is released, and the valve member 12 moves downward due to the urging force of the elastic member such as the compression spring described above, and the seat portion 12
a is seated on the valve seat 20, and the passage to the injection hole 21 is blocked,
Fuel injection stops.

A silicon nozzle 40 manufactured by the method described later is provided on the downstream side of the injection hole. The upper end surface 41a of the silicon nozzle 40 in the horizontal plane direction is fixed by the sleeve 30 so as to be in close contact with the end surface 11a of the valve body 11. The sleeve 30 is provided with a groove for defining the horizontal position of the silicon nozzle 40 and a through hole 31 through which the fuel atomized by the silicon nozzle 40 passes.

As shown in FIG. 2, the silicon nozzle 40 has a first orifice plate portion 41 and a second orifice plate portion 42, each of which has a rectangular cross-sectional shape penetrating in the plate thickness direction at the central portion thereof. Orifice 43
And a second orifice 45 that is orthogonal thereto is formed. Further, the first orifice 43 is formed in a tapered shape as it goes downward (downstream of the fuel flow) in the figure. First
The SiO ₂ film 110 is formed on the lower end surface of the orifice plate portion 41 of the above, and similarly, the SiO ₂ film 210 is formed on the upper end surface of the second orifice plate portion 42 excluding the opening portion of the second orifice 45. The two orifice plate portions are formed and are joined to each other through this SiO ₂ film.

The fuel injection characteristics of the orifice shapes provided in the first orifice plate portion 41 and the second orifice plate portion 42 will be described with reference to FIG. In FIG. 1, when the valve member 12 is lifted from the valve seat 20 of the valve body 11, fuel is injected from the injection hole 21. And the injection hole 2
The fuel injected from No. 1 passes through the through hole 44 at the intersection of the first orifice plate portion 41 and the second orifice 45 as shown in FIG. At this time, as for the fuel trying to pass through the first orifice 43, a part of the fuel is a SiO ₂ film provided on the upper surface of the second orifice plate portion 42 as indicated by solid arrows C and D in FIG. This SiO hits the upper surface 210a of 210
_{The direction of the two} membrane surfaces 210a is changed to the through hole 44 with the runway as the runway, and the spreading direction of the fuel spray is regulated by the inner wall surface forming the second orifice 45. As described above, in this embodiment, the fuels flowing through the first orifice 43 as the auxiliary runway collide with each other, and are made to flow slightly along the spray guide path formed by the second orifice 45 to form a dotted arrow E,
Spread in the F direction. Moreover, in this embodiment, the runway on the groove is formed along the first orifice 43 and the second orifice plate portion 4.
The upper surface 21 of the SiO ₂ film 210 provided on the upper surface of
And 0a.

According to this embodiment, the fuel injected from the injection hole 31 passes through the first orifice 43 and the second orifice 42 and is injected from the through hole 31. This injected fuel passes through the first orifice 43 that is tapered and then passes through the second orifice 45 that is further tapered, so that it is atomized and the injection angle is narrow in one direction. The spray shape has spray characteristics. Therefore, the fuel supplied from the intake port (not shown) to the combustion chamber of the internal combustion engine has a spray shape that facilitates combustion.

Next, the silicon nozzle 70 of the above embodiment is manufactured.
The manufacturing method will be described. FIG. 3 shows the manufacturing process.
In FIG. 3A, a plurality of silicon nozzles
First silicon wafer 1 having (100) plane orientation to be formed
End face 100a of 00 and second sill of (100) plane orientation
On the end surface 200a of the conwafer 200,
Thermal oxidation as used in conductor device manufacturing methods, atmospheric pressure C
1 μm thick SiO by VD method₂Membrane 110,
210 is formed. Furthermore, SiO₂The membrane 210 has a
Etching corresponding to the upper end opening of the second orifice 45
A pattern having a plurality of windows is formed. In that state,
SiO formed on the first silicon₂Lower end surface of the membrane 110
110a and SiO formed on the second silicon 200₂
The upper end surface 210a of the membrane 210 is abutted and
To join. The joining method is, for example, “Japanese J
individual of Applied Physics
vol. 29 No. 12 1990 "
The surface of the silicon wafer with HCl / H₂O₂Etc.
Purified with a cleaning solution, the SiO of both wafers ₂Contact the film surface
N with₂Heat treatment at 1100 ° C in atmosphere for 2 hours
Bonding is done by doing for a while. This series of work is semi-conductive
Suitable for use in a clean room used for body device manufacturing, etc.
It is right. By such processing, upper and lower silicon wafers
A sufficient bonding strength of 100, 200 is obtained.

Next, as shown in FIG. 3B, the first silicon wafer 100 is anisotropically etched to form slits corresponding to the first orifices 43.
A mask 120 is formed on the surface 100b of the first silicon wafer 100 using a silicon nitride film or a silicon oxide film. The material of this mask may be any material as long as it exhibits sufficient durability against anisotropic etching in the subsequent step. As a film forming method thereof, LPCVD or plasma CVD is used for a silicon nitride film, and an oxide film is formed by heat treatment, atmospheric pressure CVD, or spin coating is used for forming a silicon oxide film. Is done.

Next, a pattern corresponding to the first orifice 43 is formed on the mask 120 by a method used for manufacturing a semiconductor device or the like. This patterning is performed by using an infrared double-sided aligner and performing patterning while aligning with the pattern formed on the SiO ₂ film 210 of the _second silicon wafer 200. Alternatively, these first and second silicon wafers 10
A second silicon wafer 200 before bonding 0, 200
An etching pattern corresponding to the pattern applied to the upper end surface 200a of the second silicon wafer 200 is previously formed on the lower end surface 200b using a double-sided mask aligner,
After bonding, the lower end surface 2 of this second silicon wafer 200
The mask 120 on the upper end surface 100b of the first silicon wafer 100 may be patterned by a double-sided mask aligner corresponding to the pattern applied to the mask 220 of 00b.

FIG. 3C is an enlarged view of a portion of a bonded silicon wafer corresponding to one silicon nozzle. Anisotropic etching is performed to form the first orifice 43 in the first silicon wafer 100. The etching solution used at this time is NaOH aqueous solution, KOH aqueous solution, ethylenediamine + pyrocatechol + water (EP
W), hydrazine aqueous solution, tetramethylammonium hydroxide aqueous solution (TMAH), and the like. These are all alkaline anisotropic etching solutions. In the case of an alkaline anisotropic etching solution, (11
Since the 1) plane has an etching rate that is several hundredth of that of other crystal directions, if a silicon wafer is used, a taper is formed on the etched surface 43a, and an inverted pyramid-shaped etching hole, that is, an orifice as shown in FIG. 43 is formed. The formation of the etching holes does not necessarily need to have an inverted pyramid shape, and other acid-based isotropic etching solution may be used. However, a silicon nitride film or a silicon oxide film is sufficient as the mask material in the case of alkali etching, but in the case of an acid-based etching solution, the selectivity is considerably lower than that of the alkali etching solution. It must be formed thick. Only the case of using an alkaline etching solution will be described below. As shown in FIG. 3C, when the etching of the first silicon wafer 100 progresses and reaches the interface with the SiO ₂ film 110 formed on the lower end surface of the first silicon wafer 100, SiO ₂
The film 110 is exposed and the etching rate is significantly reduced.
At that time, the alkali etching is stopped, and then the exposed SiO ₂ film 110 is etched with hydrofluoric acid or the like to form the lower end surface side opening of the orifice 43. At this time, the masks 120 and 220 formed on the first and second silicon wafers 100 and 200 may also be etched. Therefore, it is necessary to make the thickness appropriate so as not to be removed.
Further, since the silicon nitride film is more resistant to hydrofluoric acid than the silicon oxide film, the silicon nitride film may be used when the thickness of the mask material is limited. Alternatively, the masks 120 and 220 may be protected with photoresist or the like and etched with hydrofluoric acid or the like.

Then, after cleaning once, alkali etching is performed again. The etching solution passes through the first orifice 43 formed in the first silicon wafer 100 and permeates into the upper surface 200a of the second silicon wafer 200 on which the SiO ₂ film 210 is not applied, and the etching proceeds. Etching is performed on the lower surface 20 of the second silicon wafer.
Since the etching rate decreases when reaching the interface with the mask 220 of 0b, the etching is stopped at that point and the mask 220 is removed. The above steps are simultaneously performed in a plurality of silicon nozzle portions on the silicon wafers 100 and 200, and finally, each silicon nozzle portion is cut to form the silicon nozzle 40 as shown in FIG. 3 (e). To be done.

As another method, in the step of FIG. 3C, the etching of the first silicon wafer 100 proceeds, and the SiO ₂ film 1 of the first silicon wafer 100 is formed.
There is a method of continuing the etching after reaching the interface with 10 and exposing the SiO ₂ film 110, and then rapidly decreasing the alkali etching rate. In this case, it takes time, but the SiO ₂ film 11 is removed by the alkaline etching solution.
0 is also etched, and the second silicon wafer 2 as it is
00 is etched to form as shown in FIG. In this case, the masks 120 and 220 need to use a silicon nitride film having a smaller etching rate than the SiO ₂ film 110. That is, by continuing the etching of the opening of the orifice applied to the first silicon wafer,
This is because it is necessary to prevent the masks 120 and 220 from being lost by etching.

As still another method, SiO ₂ formed on the lower end surface 100a of the first silicon wafer 100 in advance is used.
There is a method in which an opening corresponding to the lower opening of the first orifice 43 is patterned on the film 110, and the upper and lower patterns are aligned using infrared rays or the like to join them.
According to this method, the step of etching the SiO ₂ film 110 of the first silicon wafer 100 in FIG. 2C is unnecessary.

In addition, the first orifice 43 is previously formed in the first silicon wafer 100 by etching, and then the first orifice 43 is aligned and joined using infrared rays or the like, and the etching solution is applied from the first silicon wafer side. And the second orifice 45 of the second silicon wafer is formed by etching with the etching liquid that has passed through the first orifice 43, the same effect can be obtained.

In the above embodiments, both the first and second silicon wafers are (100) plane wafers, but those having other plane orientations such as (110) and (111) are used. Good. Further, the upper and lower wafers do not have to have the same plane orientation. However, when performing alkali etching, the etching rate changes depending on the plane orientation, so that an etching hole different from that when a (100) plane wafer is used is formed. When acid-based isotropic etching is used, there is no dependence on the crystal orientation, and therefore etching holes similar to those when using a (100) plane wafer are formed.

The film at the bonding interface may be silicon nitride as well as SiO ₂ . However, in the case of silicon nitride, when etching a silicon opening in a later step, the mask material is protected by a resist or the like, and dry etching such as CDE is performed to form the pattern opening of the first silicon wafer 100. There is a need. In the present embodiment, the method of manufacturing the nozzle in which two silicon plates are joined has been described, but the same method can be used even when more silicon plates are stacked. Needless to say. Alternatively, a metal thin film may be vapor-deposited on the surface of the formed silicon nozzle to reinforce it.

[Brief description of drawings]

FIG. 1 is a view of a discharge portion of a fuel injection valve equipped with a nozzle of the present invention.

FIG. 2 is a detailed view of the silicon nozzle of the present invention.

3 (a), (b), (c), (d) and (e) are:
FIG. 4 is a diagram showing a manufacturing process of the silicon nozzle in the present invention.

[Explanation of symbols]

40 Silicon Nozzle 41 First Orifice Plate Section 42 Second Orifice Plate Section 43 First Orifice 45 Second Orifice 110 SiO ₂ Film 210 SiO ₂ Film

Claims (2)

[Claims] 1. A plurality of silicon plates provided with an opening formed by etching, and a coating having durability against etching of the openings is provided on the facing surfaces of the plurality of silicon plates. A fluid ejection nozzle, wherein a silicon plate is bonded via the film. 2. A film having durability against etching of the silicon plates is formed on each of the facing surfaces of the plurality of silicon plates, and the plurality of silicon plates are joined via the film, and each of the silicon plates is bonded. A method for manufacturing a fluid ejection nozzle, wherein, when the opening is formed by etching, at least the opening to be etched from the surfaces to be joined is formed after joining.