JPH0829225A - Semiconductor flow rate detection device and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a semiconductor flow rate detection device wherein the mechanical strength of a thin plate having a heating element is enhanced so that it is hardly damaged in the dicing or assembling process and heat transfer from the rear face of the heating element is enhanced so that the sensitive response characteristics are improved. CONSTITUTION:A thin plate 22 is supported by four supporting beams 26 and a projection section 25 as a stopper for preventing the bending of the thin plate 22 is provided under the thin plate 22 at a short distance. Therefore, when the thin plate is pressed from the upper side, it bends a bit downward, then the rear face thereof is brought into contact with a tip portion of the projection section 25 so that the thin plate is supported from the rear face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor capable of improving the mechanical strength of a flow rate sensor for measuring the intake air amount of an engine, improving the heat transfer coefficient of the flow rate sensor, and improving the mounting accuracy. TECHNICAL FIELD The present invention relates to a flow rate detection device and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, in an electronically controlled fuel injection system for an automobile engine, it is important to accurately measure an intake air amount to the engine for air-fuel ratio control. As the air flow rate detection device, a vane type has hitherto been the mainstream, but recently, a thermal type flow rate detection device which has a small mass flow rate and is excellent in responsiveness has become widespread. Among them, a flow rate detecting device in which a detecting element is formed on a semiconductor substrate is actively studied by utilizing a semiconductor manufacturing process such as photolithography, diffusion and etching.

FIG. 24 is a sectional view showing the structure of a conventional semiconductor type flow rate detecting device. This is JP-A-58-72059.
In the semiconductor device detection chip disclosed in Japanese Patent Publication No. JP-A-2003-242, a part of the semiconductor substrate 1 is removed to form a recess 2 and a detection element 3 sandwiched by insulating layers 5 and 6 is formed on the recess 2. By holding the thin plate 4 included therein, almost all of the detection element 3 has a structure in which it is in a non-contact state with the semiconductor substrate 1. The detection element 3 includes an electrostatic element, a thermoelectric element,
A resistance element or the like is applied and can be used as a pressure sensor, a humidity sensor, a flow rate sensor, a gas sensor, or the like.

When the detecting element 3 is used as a flow rate sensor, a heating element is applied to the detecting element 3. The heating element is installed in the fluid passage to generate heat, and the flow rate is detected by utilizing the fact that the amount of heat transferred from the heating element to the fluid depends on the fluid flow rate. A permalloy element made of nickel and iron has been mainly used for this heating element.

FIG. 25 is a perspective view showing another example of a conventional semiconductor type flow rate detecting device. This is JP-A-57-1
This is the structure of the electric heater disclosed in Japanese Patent No. 78149. According to the drawing, this electric heater comprises a semiconductor substrate 11 having a through hole 10 and a selected material layer 12 formed so as to cross the through hole 10, and a cross-linked structure in which both surfaces of the selected material layer 12 are exposed. Is formed. The selected material layer 12 and the semiconductor substrate 11 are connected via the insulating layer 13. It is preferable that platinum is used for the selected material layer 12, and this platinum is used as a heating element of the flow rate sensor.

As a method of manufacturing this electric heater, first, the concave portion 14 is formed on the back surface of the semiconductor substrate 11, and then the semiconductor substrate 11 is formed.
The selected insulating layer 12 patterned into a predetermined shape is formed on the surface at a position corresponding to the concave portion 14 via the insulating layer 13. After that, the semiconductor substrate at the position where the concave portion 14 is formed is removed by etching treatment from the surface, and the selected material layer 12 is formed.
Form a cross-linked structure. The insulating layer 13 adhering to the back surface of the selected material layer 12 is thereafter removed by etching.

However, when the above-mentioned structure is used as a flow rate sensor, the thin plate 4 on which the heat generating element and the temperature detecting element are formed is as thin as 0.8 to 1.2 μm. However, there is a problem that it is easily broken and easily broken during dicing or during the assembly process. In addition, since it is difficult for the fluid to enter the recess 14 below the thin plate 4, heat transfer from the back surface of the heat generating element is limited, and the characteristics of the flow rate sensor deteriorate. Furthermore, the elemental metals such as platinum, iron and nickel used for the heating element are not being used in the existing semiconductor process line, and there is a problem that they are not suitable for future mass production. Further, there is a problem in that the characteristics of the flow rate detection chip vary due to variations in attachment when the semiconductor substrates are bonded.

[0008]

Since the conventional semiconductor type flow rate detecting device is constructed as described above, the thin plate having the heating element is particularly vulnerable to vertical impact and is easily broken during dicing or during the assembly process. There was a problem.
There is also a problem that heat transfer from the back surface of the heating element is limited, and the sensitivity and responsiveness of the semiconductor type flow rate detection device are reduced. Furthermore, platinum and iron used for heating elements,
There is also a problem that simple metals such as nickel are not suitable for future mass production. Further, there is a problem in that variations in sensitivity and responsiveness of the semiconductor type flow rate detection device occur due to variations in attachment when the semiconductor substrates are bonded.

Claims 1 and 14 have been made to solve the above problems, and improve the mechanical strength of a thin plate having a heating element so that it is unlikely to break during dicing or during the assembly process. An object of the present invention is to obtain a semiconductor type flow rate detection device that can be used.

It is an object of the present invention to provide a method for manufacturing a semiconductor type flow rate detecting device, which can improve the mechanical strength of a thin plate having a heating element and can be prevented from being easily broken during dicing or during an assembly process. And

It is an object of the present invention to obtain a semiconductor type flow rate detecting device capable of promoting heat transfer from the rear surface of the heating element and improving sensitivity and responsiveness.

It is an object of the inventions of claims 7 and 13 to obtain a semiconductor type flow rate detecting device capable of reducing heat conduction loss from the heating element to the semiconductor substrate and improving sensitivity and responsiveness. .

According to an eighth aspect of the present invention, it is possible to obtain a semiconductor type flow rate detecting device capable of precisely controlling the positional relationship of the heating elements in the fluid passage, reducing variations in the positions of the heating elements, and further realizing cost reduction. To aim.

The invention according to claims 9 to 10 is capable of precisely controlling the positional relationship of the heating elements in the fluid passage, reducing variations in the positions of the heating elements, and further realizing cost reduction. It aims at obtaining the manufacturing method of.

It is an object of the invention of claim 11 to obtain a semiconductor type flow rate detecting device capable of promoting heat transfer from a heating element to a fluid and improving sensitivity and responsiveness.

It is an object of the invention of claim 12 to obtain a method of manufacturing a semiconductor type flow rate detecting device capable of promoting heat transfer from a heating element to a fluid and improving sensitivity and responsiveness.

It is an object of the invention of claim 15 to obtain a semiconductor type flow rate detecting device capable of preventing variations in sensitivity and responsiveness due to variations in attachment when adhering semiconductor substrates.

It is an object of the invention of claim 16 to obtain a semiconductor type flow rate detecting device in which a single metal used as a heating element can be easily applied to an existing semiconductor process.

[0019]

According to another aspect of the present invention, there is provided a semiconductor type flow rate detecting device, wherein a convex portion is located at a bottom portion of a concave portion formed on a semiconductor substrate, and a tip is separated from a thin plate forming a conductive material layer. It is the one that I tried to do.

In the semiconductor type flow rate detecting device according to the second aspect of the present invention, at the process step of forming the recess, the tip is tapered toward the thin plate and is separated from the thin plate by the anisotropic etching technique. The convex portion is formed on the bottom of the concave portion.

In the semiconductor type flow rate detecting device according to the third aspect of the present invention, the through hole connects the recess of the semiconductor substrate and the back surface of the semiconductor substrate, and the low pressure holding means is the through hole on the back surface side of the semiconductor substrate. The pressure generated at the pressure is kept lower than the pressure generated at the opening on the front surface side of the semiconductor substrate.

In the semiconductor type flow rate detecting device according to a fourth aspect of the present invention, the streamline type support which is a low pressure holding means has a wide portion and a narrow portion, and the passage is formed in the streamline type support. One of the openings is connected to the opening on the back surface of the semiconductor substrate, and the other opening is located in a portion wider than the position of the semiconductor substrate.

In the semiconductor type flow rate detector according to the fifth aspect of the present invention, the support which is the low pressure holding means holds the semiconductor substrate so that the back surface thereof forms an acute angle with the flow direction of the fluid.

According to a sixth aspect of the present invention, there is provided a semiconductor type flow rate detecting device, wherein at least one step portion which is a low pressure holding means is provided on the back surface of the semiconductor substrate.

In the semiconductor type flow rate detecting device according to the invention of claim 7, the second recess surrounds the periphery of the recess formed in the semiconductor substrate.

According to another aspect of the semiconductor type flow rate detecting device of the present invention, a pair of thin plates supported by the semiconductor substrate by at least one supporting portion are located at both openings of a fluid passage that penetrates the semiconductor substrate. The conductive material layer is formed on at least one of the pair of thin plates.

According to a ninth aspect of the present invention, there is provided a semiconductor type flow rate detecting device, wherein one surface of a semiconductor substrate is provided with a first thin plate which has a conductive material layer and is supported by the semiconductor substrate by at least one supporting portion. The step of forming a second thin plate having a conductive material layer and supported on the semiconductor substrate by at least one supporting portion on the other surface of the semiconductor substrate; The semiconductor substrate located directly below the first thin plate and the second thin plate is removed, and a fluid passage that penetrates the semiconductor substrate is formed.

According to a tenth aspect of the present invention, there is provided a semiconductor type flow rate detecting device, wherein a first thin plate having a conductive material layer is supported on at least one supporting portion on a first semiconductor substrate, and the first thin plate is provided on one surface of the semiconductor substrate. A step of forming, a step of forming a through hole directly under the first thin plate by an anisotropic etching technique, and a step of supporting a second semiconductor substrate by at least one supporting portion and having a conductive material layer. Forming a thin plate on one surface of the semiconductor substrate, forming a through hole directly below the second thin plate by an anisotropic etching technique, and adjusting the through holes so that the through holes are aligned with each other. It is manufactured by a process of bonding the back surfaces of the substrates together.

In the semiconductor flow rate detecting device according to the invention of claim 11, a thin plate having a conductive material layer supported by the semiconductor substrate by at least one supporting portion has a central portion formed so as to penetrate the semiconductor substrate. It is arranged so as to be located at the narrowest part of the fluid passage which is the narrowest.

According to a twelfth aspect of the present invention, in a semiconductor type flow rate detecting device, a thin plate having a conductive material layer is supported on at least one supporting portion on a first semiconductor substrate, and a thin plate having a conductive material layer is provided on one surface of the first semiconductor substrate. A step of forming, a step of performing anisotropic etching from the other surface of the first semiconductor substrate to form a tapered through hole that spreads downwardly just below the thin plate, and one of the second semiconductor substrate Is anisotropically etched from the surface of the second semiconductor substrate to form a tapered through hole narrowing downward from one surface of the second semiconductor substrate, and the surface having a small opening area of the through hole is aligned with the above. It is manufactured by a step of bonding the first semiconductor substrate and the second semiconductor substrate.

In the semiconductor type flow rate detector according to the thirteenth aspect of the present invention, the second conductive material layer is located above the recess, and is formed near the base end of the supporting portion of the thin plate in which the conductive material layer is formed. It was done like this.

In the semiconductor type flow rate detecting device according to the fourteenth aspect of the present invention, the reinforcing beam is formed in the vicinity of the base end of the supporting portion so as to intersect with the supporting portion, and the supporting portion is reinforced.

According to a fifteenth aspect of the present invention, in the semiconductor type flow rate detecting device, a U-shaped support body fixed by a resin mold fixes both ends of the semiconductor substrate.

In the semiconductor type flow rate detecting device according to the sixteenth aspect of the present invention, the conductive material layer is made of a metal silicon compound such as WSi ₂ , TiSi ₂ or the like.

[0035]

According to the semiconductor type flow rate detecting device of the first aspect of the invention, the thin plate is provided by providing the convex portion located at the bottom of the concave portion formed in the semiconductor substrate and having the tip separated from the thin plate forming the conductive material layer. It has become possible to prevent the upper and lower bends of the.

In the semiconductor type flow rate detecting device according to the second aspect of the present invention, in the process step of forming the concave portion, the tip is tapered toward the thin plate by the anisotropic etching technique, and the tip is separated from the thin plate. By providing the step of forming the portion on the bottom of the recess, it is possible to prevent the thin plate from being bent up and down.

In the semiconductor type flow rate detecting device according to the third aspect of the present invention, a through hole that connects the concave portion of the semiconductor substrate and the back surface of the semiconductor substrate is provided, and the pressure generated in the opening portion of the through hole on the back surface side of the semiconductor substrate is provided. By providing the low pressure holding means for keeping the pressure lower than the pressure generated in the opening portion on the front surface side of the semiconductor substrate, the opening portion on the back surface side of the semiconductor substrate can be made in a state in which the pressure is lower than that on the front surface side of the semiconductor substrate. The fluid also flows into the concave portion on the side.

According to a fourth aspect of the present invention, there is provided a semiconductor type flow rate detecting device, which is provided with a streamlined support which is a low pressure holding means having a wide portion and a narrow portion, and is formed in the streamlined support body, and one opening is formed in the semiconductor. By connecting to the opening on the back surface of the substrate and providing a passage in which the other opening is located wider than the position of the semiconductor substrate,
The pressure on the opening on the rear surface side of the semiconductor substrate can be set to be lower than that on the front surface side of the semiconductor substrate, and the fluid also flows into the concave portion on the lower side of the thin plate.

According to another aspect of the semiconductor type flow rate detecting device of the present invention, the semiconductor substrate is provided with a support which is a low pressure holding means for holding the back surface of the semiconductor substrate at an acute angle with respect to the flow direction of the fluid. The opening on the back surface side of the substrate can be made to have a lower pressure than that on the front surface side of the semiconductor substrate, and the fluid also flows into the thin plate concave portion.

In the semiconductor type flow rate detecting device according to the invention of claim 6, at least one step portion which is a low pressure holding means is provided on the back surface of the semiconductor substrate so that the opening on the back surface of the semiconductor substrate is opened from the front surface side of the semiconductor substrate. Can also be in a low pressure state, and the fluid will also flow into the concave portion on the lower side of the thin plate.

According to a seventh aspect of the present invention, there is provided a semiconductor type flow rate detecting device which comprises a second portion surrounding a recess formed in a semiconductor substrate.
By providing the concave portion, it is possible to reduce the heat conduction loss from the heating element to the semiconductor substrate.

According to the eighth aspect of the present invention, there is provided a semiconductor type flow rate detecting device, which is located at both openings of a fluid passage that penetrates a semiconductor substrate and the fluid passage, and is supported by the semiconductor substrate by at least one support portion. By providing the pair of thin plates and the conductive material layer formed on at least one of the pair of thin plates, the position of the thin plates in the fluid passage and the relative position of the pair of thin plates can be precisely controlled.

According to a ninth aspect of the present invention, there is provided a semiconductor type flow rate detector having a conductive material layer on one surface of a semiconductor substrate.
Forming a first thin plate supported by the semiconductor substrate by at least one supporting portion, and having a conductive material layer on the other surface of the semiconductor substrate, supporting the semiconductor substrate by the at least one supporting portion By the step of forming the second thin plate to be formed and the anisotropic etching technique.
And the step of forming a fluid passage that penetrates the semiconductor substrate by removing the semiconductor substrate located immediately below the second thin plate and the second thin plate. The relative position of the thin plate can be controlled precisely.

According to a tenth aspect of the present invention, in a semiconductor type flow rate detecting device, a first thin plate supported by a first semiconductor substrate by at least one supporting portion and having a conductive material layer is provided on one side of the first semiconductor substrate. A surface, a step of forming a through hole directly below the first thin plate by an anisotropic etching technique, and a conductive material layer supported on the second semiconductor substrate by at least one supporting portion. Second
The step of forming the thin plate on one surface of the second semiconductor substrate and the step of forming a through hole directly below the second thin plate by the anisotropic etching technique so that the through holes are aligned with each other. By providing the step of attaching the back surfaces of the first and second semiconductor substrates to each other, the position of the thin plate in the fluid passage and the relative position of the two thin plates can be precisely controlled.

According to the eleventh aspect of the present invention, in a semiconductor type flow rate detecting device, a thin plate having a conductive material layer supported by a semiconductor substrate by at least one supporting portion has a central portion formed so as to penetrate the semiconductor substrate. By providing the heating element in the narrowest part of the fluid passage which is the narrowest, the heating element can be installed in the place where the flow velocity is the fastest in the fluid passage, and the heat transfer from the heating element can be promoted. .

According to a twelfth aspect of the present invention, in the semiconductor type flow rate detecting device, the thin plate supported by the first semiconductor substrate by at least one supporting portion and having a conductive material layer is the first plate.
Of the semiconductor substrate, and anisotropically etching the other surface of the first semiconductor substrate to form a tapered through hole that spreads downwardly just below the thin plate. A step of performing anisotropic etching from one surface of the second semiconductor substrate to form a tapered through hole narrowing downward from one surface of the second semiconductor substrate; and a small opening area of the through hole. By providing the step of bonding the back surfaces of the first semiconductor substrate and the second semiconductor substrate so that the surfaces thereof coincide with each other, the heating element is installed in the narrowest part of the fluid passage having the highest flow velocity. Therefore, heat transfer from the heating element can be promoted.

In the semiconductor type flow rate detector according to the thirteenth aspect of the present invention, the second conductive material layer is formed above the recess and is formed in the vicinity of the base end of the supporting portion of the thin plate in which the conductive material layer is formed. As a result, the heat conduction loss from the heating element to the semiconductor substrate is reduced.

According to the semiconductor type flow rate detecting device of the fourteenth aspect of the present invention, by providing the reinforcing beam near the base end of the supporting part so as to reinforce the supporting part, the reinforcing beam is provided.
It becomes possible to improve the mechanical strength of the thin plate.

According to the semiconductor type flow rate detecting device of the fifteenth aspect of the present invention, by providing the U-shaped support body fixed by the resin mold for fixing both ends of the semiconductor substrate,
Variations in attachment when bonding semiconductor substrates are reduced.

In the semiconductor type flow rate detecting device according to the sixteenth aspect of the present invention, an existing semiconductor process can be easily applied by using a metal silicon compound such as WSi ₂ or TiSi ₂ for the conductive material layer. Become.

[0051]

EXAMPLES Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 (a) is a plan view showing a semiconductor type flow rate detecting device according to an embodiment of the invention of claim 1, and FIG. 1 (b) is a state when FIG. 1 (a) is cut along AA. It is sectional drawing shown. In the figure, the same reference numerals as those used in the related art indicate the same or corresponding portions, and will be omitted. In the figure, 20 is a flow rate detecting chip (semiconductor type flow rate detecting device) in the first embodiment, 21 is a semiconductor substrate, 22 is a thin plate formed on the semiconductor substrate 21, and 23 is a thin plate 22 using an anisotropic etching technique. A concave portion formed directly below, 24 is formed in the thin plate 22, and a heating element (conductive material layer) for detecting the fluid flow rate by utilizing the fact that the amount of convective heat transfer to the fluid depends on the flow rate, 25 is directly below the thin plate 22. A convex portion formed on the bottom of the concave portion 23 located at, and a support beam (support portion) 26 for supporting the thin plate 22.

In order to reduce the heat conduction loss to the semiconductor substrate 21 and to reduce the heat capacity of the thin plate 22, the thin plate 22 is designed to have a very small thickness of 2-3 microns. Therefore, since the mechanical strength, particularly the force in the vertical direction, is weak and there is a risk of breakage, in this embodiment, the thin plate 22 is supported by the four support beams 26, and at the lower side of the thin plate 22. Thin plate 22 at a slight distance
Convex part 2 which has a role as a stopper to prevent bending of
5 is provided. Therefore, when the thin plate 22 receives a force from above, the thin plate 22 bends downward to some extent, but the back surface of the thin plate 22 contacts the tip of the convex portion 25, and the thin plate 22 is supported from the back surface. As a result, the thin plate 22 has four support beams 2
Since it is supported by 6 and one convex portion 25, the resistance against the force from above is increased and the thin plate 22 is prevented from being broken.

When the tip area of the convex portion is formed to be 1/10 or less of the cross-sectional area of the support beam 26 of the thin plate 22, the thin plate 22 and the convex portion 25 contact with each other via the convex portion 25 when the tip of the thin plate 22 contacts. The amount of heat conduction is extremely smaller than the amount of heat conduction through the support beam 26, and does not significantly affect the characteristics of the flow rate detection chip. In addition, the convex portion 25 of FIG.
Is formed on the lower side of the thin plate 22, but may be formed on the upper side or both sides of the thin plate 22. Also, in FIG.
Although only one protrusion 25 is shown, it is clear that a plurality of protrusions 25 may be present. In this case, a larger effect can be obtained.

Next, a method of manufacturing the flow rate detecting chip 20 in the first embodiment will be described. FIG. 2 is a cross-sectional view showing the manufacturing process of the flow rate detection chip 20 in the first embodiment. First, the dielectric layer 101 is formed after forming the insulating layer 100 on the (100) semiconductor substrate 21 (b). next,
The dielectric layer 101 is patterned into a predetermined shape, the insulating layer 100 is etched by using the patterned dielectric layer 101 as a mask, the exposed portion of the semiconductor substrate 21 is selectively oxidized, and then the entire surface is again etched. Oxidize. As a result, the thick insulating layer 100 can be formed only on the exposed portion of the semiconductor substrate 21 (c). This thick insulating layer 100 will later become the base of the thin plate 22. Then, the remaining dielectric layer 101 and the insulating layer 100 thereunder are removed to expose the semiconductor substrate 21 (d). This exposed portion becomes a later etching window. Next, the conductive material layer 10 is formed on the entire surface.
2 is formed and patterned (e), then the conductive material layer 10 is formed.
2 is covered with a passivation film to form the lead portion 103 (f). After that, the periphery of the thick insulating layer 100 is removed by an anisotropic etching solution to form the recess 23, and the thin plate 22 supported in the hollow is formed (g).

The semiconductor substrate 21 made of a silicon material is set to K.
When anisotropically etching with an alkaline solution such as OH, the etching rate (etching rate) differs depending on the crystal orientation of silicon, so it is possible to fabricate complex shapes with good reproducibility by combining the substrate surface direction and mask shape. Is. Therefore, in the manufacturing step (g), the lower portion of the thin plate 22 can be left with the pyramidal protrusion on the bottom surface of the recess 23 only by anisotropic etching from the lateral direction.

Specifically, for example, the size of the thin plate 22 is 6
In the case of 0 × 200 μm, it has been confirmed by an experiment that, when etching is performed at KOH 5 wt% and 70 ° C. for about 45 minutes, a convex portion that is hidden by the thin plate 22 remains under the thin plate 22. The etching time in this case depends on the size of the thin plate 22, but when the above etching solution is used, the diagonal etching rate of 2.3 μm / min is obtained. When different, the etching time can be calculated by considering the size. Also, if the etching solution is different,
Using the etching rate of the etching solution,
An appropriate etching time has to be calculated.

Example 2. FIG. 3 is a sectional view showing a semiconductor type flow rate detecting device according to an embodiment of the present invention. In the figure, 30 is a flow rate detecting chip in the second embodiment,
Reference numeral 31 is a semiconductor substrate, 32 is a thin plate formed on the semiconductor substrate 31, 33 is a recess formed directly below the thin plate 32 using an anisotropic etching technique, 34 is a heating element formed on the thin plate 22, and 35 is a recess. It is a through hole 35 that connects the bottom surface of 33 to the back surface of the semiconductor substrate 31. By keeping the pressure of the rear surface side opening 35a of the through hole 35 lower than the pressure of the front surface side opening 35b, the fluid flowing along the surface of the semiconductor substrate 31 as shown by an arrow A in the figure. Is pulled by the low pressure on the back surface side of the semiconductor substrate 31, enters the recess 33 from the left side in the drawing, and comes out to the right side in the drawing of the recess 33. As a result, heat transfer from the back surface of the thin plate 32 is promoted, the heat transfer characteristics of the entire flow rate detection chip 30 are improved, and the sensitivity and responsiveness of the flow rate detection chip 30 are improved.

Next, a method of keeping the back side opening 35a of the through hole 35 of the flow rate detecting chip 30 at a pressure lower than that of the front side opening 35b will be described. FIG. 4 shows claim 4.
3 is a cross-sectional view showing an example of the low pressure holding means in FIG. In the figure, 36 is a streamlined support (low pressure holding means), 37 is a hole (low pressure holding means) formed in a wide portion of the streamlined support 36, 38 is a rear side opening of the hole 37 and the through hole 35. 35a is a passage (low pressure holding means) that connects with 35a. The flow rate detecting chip 30 is embedded behind the streamlined support 36 so that the surface of the flowrate detection chip 30 and the surface of the streamlined support 36 are aligned with each other.
A passage 38 is provided inside the streamlined support 36, and one end thereof communicates with the rear surface side opening 35 a of the flow rate detection chip 30 and the other end communicates with the hole 37.

Therefore, when the streamlined support member 36 is positioned so that the wide portion of the streamlined support member 36 faces the flow direction of the fluid (arrow B), the flow velocity of the wide portion of the streamlined support member 36 is increased to the rear. Since it is faster than the flow velocity in the narrow part, the pressure is lower in the front than in the rear according to Bernoulli's theorem. Therefore, the pressure of the rear surface opening 35a of the through hole 35, which is connected to the front hole 37 of the streamlined support 36 via the passage 38, can be kept lower than the pressure of the front surface side opening 35b. The fluid easily enters the recess 33 of the flow rate detection chip 30.

A specific example of the case where the streamlined support 36 is installed in the intake air pipe of the engine will be described. Figure 5
FIG. 5A is a plan view showing a state in which the streamlined support is attached to the intake air pipe of the engine, and FIG. 5B is a front view showing a state in which the streamlined support is attached to the intake air pipe of the engine. is there. In the figure, 39 is an intake air pipe of the engine, and 40 is a mounting member provided in the intake air pipe 39 of the engine. Position the streamlined support 36 to which the flow rate detection chip 30 is attached to the attachment member 40 in the intake air pipe 39 of the engine so that the wide portion of the streamlined support 36 faces the air flow direction (arrow B). As a result, the flow velocity in the wide portion of the streamlined support 36 is higher than the flow velocity in the narrow portion behind the streamlined support member 36, so the pressure is lower in the front than in the rear. Therefore, the pressure of the rear surface side opening portion 35 a of the through hole 35 is equal to that of the front surface side opening portion 35.
Since the pressure can be kept lower than the pressure of b, the air easily enters the recess 33 of the flow rate detection chip 30.

Next, another method for keeping the back side opening 35a of the through hole 35 at a pressure lower than that of the front side opening 35b will be described. FIG. 6 is a sectional view showing an embodiment of the low pressure holding means in claim 5. In the above example, the flow rate detection chip 30 is incorporated into the streamlined support 36, so that the back surface side opening 35a is kept at a lower pressure than the front surface side opening 35b. However, in the present embodiment, as shown in FIG. 6, by arranging the back surface of the flow rate detection chip 30 at an acute angle α with respect to the fluid flow direction (arrow C), the back surface side of the flow rate detection chip 30 is arranged. Flow rate (arrow C1) becomes faster than the flow rate on the front surface side (arrow C1), and the pressure of the rear surface opening 35a of the through hole 35 is changed to the front surface side opening 35b.
Can be kept below the pressure of. Therefore, the fluid easily enters the recess 33 of the flow rate detection chip 30.

A specific example in which the back surface of the flow rate detecting chip 30 is held at an acute angle α with respect to the horizontal plane in the fluid flow direction will be described. FIG. 7A is an enlarged perspective view showing an example of a support body that holds the back surface of the flow rate detection chip at an acute angle with respect to the fluid flow direction, and FIG. 7B is a support body of FIG. 7A. FIG. 7C is a plan view showing a state in which is installed in the intake air pipe of the engine, and FIG. 7C is a front view showing a state in which the support of FIG. 7A is installed in the intake air pipe of the engine. In the figure, reference numeral 41 denotes a package (low pressure holding means) mounted in the intake air pipe of the engine, and the back surface of the flow rate detecting chip 30 is a horizontal plane in the air flow direction (arrow D) in the intake air pipe 39 of the engine. Is held at an acute angle α with respect to. Therefore, the through hole 35
Since the pressure of the rear surface side opening portion 35a can be kept lower than that of the front surface side opening portion 35b, the air easily enters the concave portion 20 of the flow rate detecting chip 30.

Further, a specific example in which the back surface of the flow rate detecting chip 30 is held at an acute angle α with respect to a surface perpendicular to the fluid flow direction will be described. 8A is an enlarged perspective view showing an example of a support body that holds the back surface of the flow rate detection chip at an acute angle with respect to the flow direction of the fluid, and FIG. 8B is a support body of FIG. 8A. FIG. 8 is a plan view showing a state in which is installed in the intake air pipe of the engine, and FIG. 8C is a front view showing a state in which the support of FIG. 8A is installed in the intake air pipe of the engine. In the figure, reference numeral 42 denotes a holder (low pressure holding means) mounted in the intake air pipe of the engine, and the back surface of the flow rate detection chip 30 is perpendicular to the flow direction (arrow E) of the air in the intake air pipe 39 of the engine. It is bent so that it forms an acute angle α with the surface. Therefore, the pressure of the rear surface side opening portion 35a of the through hole 35 can be kept lower than that of the front surface side opening portion 35b, so that air easily enters the concave portion 20 of the flow rate detection chip 30.

Example 3. FIG. 9 is a sectional view showing another embodiment of the low pressure holding means in claim 6. In the figure, 43 is a flow rate detecting chip in the third embodiment, 44
Is a semiconductor substrate, 45 is a thin plate having a conductive material layer, 46 is a recess formed directly under the thin plate 45, and 47 is a through hole that connects the bottom surface of the recess 46 and the back surface of the semiconductor substrate 44.
The low pressure holding means etches the back surface of the semiconductor substrate 31 shown in FIG. 3 to form the step portion 48. Therefore, the back surface of the semiconductor substrate 44 becomes closer to a curved line than the front surface, and the velocity of the fluid (F1) near the back surface of the semiconductor substrate 44 becomes faster than the velocity of the fluid (F2) near the front surface, so that the through hole 47 is formed. The pressure in the rear opening 47a can be kept lower than the pressure in the front opening 47b, and as a result, the fluid easily enters the recess 46. By the way, although the number of the step portions 48 is two in the present embodiment, it is better to increase the number of step portions 48 so that the back surface of the semiconductor substrate 44 has a smoother curve.

Example 4. FIG. 10A is a plan view showing a semiconductor type flow rate detecting device according to an embodiment of claim 7.
FIG. 10 (b) is a sectional view of the semiconductor type flow rate detector according to the embodiment of the invention of claim 7 taken along the line AA of FIG. 10 (a). In the figure, 50 is a flow rate detecting chip in the fourth embodiment, 51 is a semiconductor substrate, 52 is a thin plate having a conductive material layer, 53 is a recess formed directly below the thin plate 52, 54 is a support beam, and 55 is a recess 53. The second concave portion is formed so as to surround the periphery. In the fourth embodiment, the second recess 55 is provided so as to surround the periphery of the recess 53, and on the second recess 55, four support beams 54 are bridged in an extended form. ing. By forming the second recess 55, the amount of heat escaping to the semiconductor substrate 51 via the support beam 54 can be further reduced. Moreover, the mechanical strength is superior to the case where the length of the support beam 54 is simply increased.

Example 5. 11 and 12 are sectional views showing a semiconductor type flow rate detecting device according to an embodiment of the present invention. In the figure, 60 is a flow rate detecting chip in the fifth embodiment, 61 is a semiconductor substrate, and 62 is a semiconductor substrate 61.
Fluid passage formed so as to penetrate through the semiconductor substrate 61 and narrowest in the central portion of the semiconductor substrate 61, 63 forms a conductive material layer, and is a thin plate located in one opening 62a of the fluid passage 62, and 64 indicates a conductive material. The second thin plate does not form a layer and is located in the other opening 62b of the fluid passage 62. In this embodiment, the flow rate detection chip 60 is arranged in the fluid so that the flow of the fluid (arrow G) escapes from the opening portion 62b of the fluid passage 62 to the opening portion 62a, and the dust contained in the fluid is removed. By attaching to the second thin plate 64, it is possible to prevent dust and the like from attaching to the thin plate 63 and prevent deterioration of the characteristics. Further, since the fluid is contracted to the vicinity of the center of the fluid passage 62, the fluid also flows into the shaded portion of the second thin plate 64, and sufficient heat transfer characteristics with the thin plate 63 can be secured.

Further, in the above example, the second thin plate 64 is used as a dust adhesion preventing material, but a temperature-sensitive conductive material layer is formed in the second thin plate 64 to detect the fluid temperature. It may be used as a detection element. By using the second thin plate 64 as a fluid temperature detecting element, temperature compensation can be performed based on the fluid temperature detected by the second thin plate 64, so that it is necessary to separately provide a temperature detecting element for temperature compensation. Will be eliminated, leading to cost reduction. In this case, the second thin plate 64 does not have to be arranged at a position facing the thin plate 63, and as shown in FIG. 12, the second thin plate 64 may be arranged shifted to the end of the opening 62b.

Next, a method of manufacturing the flow rate detecting chip 60 according to the fifth embodiment will be described. FIG. 13 is a sectional view showing an embodiment of the invention of claim 9. First, on both surfaces of the polished semiconductor substrate 61 (a),
After forming the dielectric layer 105 (b), the first dielectric layer 10 is formed.
A conductive material layer 106 is formed on the layer 5 (c). As the first dielectric layer 105, SiO ₂ , SiN _x (Si ₃ N _{4) is used.}
, Etc.), Ta ₂ O ₅ or the like using a method such as a thermal oxidation furnace or CVD or sputtering, and the first dielectric layer 105 at this time may be formed under the condition that the film stress is as small as possible. desirable. Further, regarding the manufacturing method shown in FIG. 13 including the first dielectric layer 105, it is not necessary to form both surfaces at the same time, and one surface may be alternately formed. However, when the second thin plate 64 is used as a dust adhesion preventing material for the thin plate 63, the conductive material layer 106 may be formed only on the first dielectric layer 105 on one surface.

Next, the conductive material layer 106 is patterned into a predetermined shape by photolithography and dry etching technology such as IBE or RIE (d), and then the conductive material layer 10 is formed.
A lead portion 107 for connecting 6 and the circuit portion is formed by photolithography and etching (e). When this lead portion 107 is not formed on the same substrate as the circuit portion, it is further connected by bonding. Then, in order to protect the resistive element portion and the wiring portion, the second dielectric layer 1
After forming 08 on the entire surface (f), exposed portions 109 and 110 of the semiconductor substrate 60 having a predetermined shape and size are formed on the first dielectric layer 105 and the second dielectric layer 108 by photolithography and etching. Form (g). As the second dielectric layer 108, SiO ₂ , SiN _x (including Si ₃ N ₄ ), Ta ₂ O ₅ or the like is formed by a method such as CVD or sputtering. At this time, it is desirable that the second dielectric layer 108 is formed under the condition that the film stress is as small as possible like the first dielectric layer 105.

Further, the portion of the semiconductor substrate 61 which becomes the fluid passage 62 is removed by using the anisotropic etching technique to form the fluid passage 62 (h). In this case, the fluid passage 62
Is formed narrowest in the central portion of the semiconductor substrate 61. The reason is that when the semiconductor substrate 61 which is a silicon substrate is anisotropically etched with an alkaline solution such as KOH,
Since the etching rate (etching rate) varies depending on the crystal orientation of silicon, specifically, the etching rate in the depth direction of the substrate is several hundred times faster than the etching rate in the lateral direction, so that the etching progresses in the depth direction. However, since it is difficult to etch in the lateral direction, it is formed to be the narrowest in the central portion of the semiconductor substrate 61. Then, the semiconductor substrate 61 is cut into an appropriate chip size before or after anisotropic etching is performed to form the flow rate detection chip 60 having the cross-sectional views shown in FIGS. 11 and 12. be able to.

Further, another method of manufacturing the flow rate detecting chip 60 in the fifth embodiment will be described. FIG. 14 is a sectional view showing a method of manufacturing a semiconductor type flow rate detecting device according to an embodiment of the present invention. In this manufacturing method, the flow rate detecting chip 60a on the upper side and the flow rate detecting chip 60b on the lower side are manufactured separately, and then the two are bonded to manufacture one flow rate detecting chip 60. FIG.
The manufacturing steps (a) to (g) of FIG. 4 are the manufacturing steps (a) of FIG.
In (g) to (g), the only difference is whether the constituent members such as the first dielectric layer 105 and the second dielectric layer 108 are formed on both sides or one side, and therefore the description thereof is omitted. 14
In step (i), the upper flow rate detecting chip 60a and the lower flow rate detecting chip 60b are joined so that the through holes 65 overlap with each other and cut into an appropriate chip size, as shown in FIGS. A flow rate detecting chip having the cross-sectional view shown in FIG. 12 can be produced.

Example 6. FIG. 15 is a sectional view of a flow rate detecting chip according to an embodiment of the present invention. In the figure, 70 is a flow rate detecting chip in Example 6, 7
1 is the narrowest position of the fluid passage 62. In the fifth embodiment, the thin plate 63 having the conductive material layer is formed in one opening 62a of the fluid passage 62, and the second thin plate 64 is formed in the other opening 62b. By forming the thin plate 63 having the conductive material layer in the narrowest portion 71 of the fluid passage 62 having the highest flow velocity, the heat transfer characteristics can be improved.

Next, a method of manufacturing the flow rate detecting chip 70 in the sixth embodiment will be described. FIG. 16 shows claim 12.
FIG. 6 is a cross-sectional view showing the method for manufacturing the semiconductor type flow rate detecting device according to the embodiment of the invention. First, the (100) semiconductor substrate 6
2 are prepared (a), the insulating layer 100 and the dielectric layer 101 are formed on both surfaces of the first semiconductor substrate 61 (b), and the second semiconductor substrate has the insulating layer 100 and the dielectric layer only on its surface. Form layer 101 (b). Next, insulating layer 1 on both sides
00 and the dielectric layer 101 are formed on the substrate, the insulating layer 100 is patterned using the dielectric layer 101 as a mask to expose a part of the semiconductor substrate 61. And
The exposed portion of the semiconductor substrate 61 is oxidized to form an insulating layer 100 which will be the base of the thin plate 63 (c), and the semiconductor substrate 61 which will later become the fluid passage 62 will be exposed (d).

Further, after forming a conductive material layer 102 on the insulating layer 100 and patterning it, the conductive material layer 1 is formed.
02 is covered with a passivation film to form the lead portion 103 (e). Then, using the dielectric layer 101 on the back surface of the semiconductor substrate 61 as a mask, the insulating layer 100 is patterned to expose (111) the portion of the semiconductor substrate 61 which will be a window for forming the through hole 114. The area of the exposed portion 111 is determined so that the circumference of the bottom surface thereof coincides with the circumference of the exposed portion 112 on the front surface side of the semiconductor substrate 61 when this portion is anisotropically etched. And
Anisotropic etching is performed from the exposed back surface portion 111 to float the thin plate 63 (f).

The second semiconductor substrate 61 is also the dielectric layer 1
The insulating layer 100 is patterned by using 01 as a mask to expose a part 113 of the semiconductor substrate 61 (c).
The area of the exposed portion 113 is made equal to the area of the exposed portion 111. Anisotropic etching is performed from the exposed portion 113 to form a through hole 114 that penetrates to the back surface (d). Finally, the front surface of the first semiconductor substrate 61 and the back surface of the second semiconductor substrate 61 are joined so that the openings of the through holes 114 are aligned with each other to form the fluid passage 62. It is desirable to use anodic bonding for this bonding, but it is also possible to use an adhesive layer or an adhesive. In this way, the fluid passage 6
It is possible to fabricate a structure in which the thin plate 63 having a conductive material layer is arranged on the second narrowest portion 71.

Example 7. 17A is a plan view of a semiconductor type flow rate detecting device according to an embodiment of the present invention of claim 13, and FIG. 17B is a semiconductor type flow rate detecting device according to an embodiment of the present invention of claim 13. It is sectional drawing when it cut | disconnects by the BB line. In the figure, 75 is a flow rate detecting chip in the seventh embodiment, 76 is a semiconductor substrate, 78 is a thin plate having a conductive material layer, 79 is a recess formed immediately below the thin plate 78, and 80 is a second conductive material layer. . In this flow rate detecting chip 75, a recess 79 is formed in a semiconductor substrate 76 by anisotropic etching, and a thin plate 78 is cross-linked on the recess 79, and a conductive material layer 77 serving as a heating element is provided on the thin plate 78. ing.

A second conductive material layer 80 is formed on the semiconductor substrate 76 near the supporting portion of the thin plate 78. The second conductive material layer 80 also functions as a heating element and reduces the temperature difference between the thin plate 78 and the semiconductor substrate 76. By doing so, the amount of heat conduction from the thin plate 78 to the semiconductor substrate 76 can be reduced, and if the amount of heat conduction to the semiconductor substrate 76 is reduced, the responsiveness of the flow sensor is improved. The temperature of the second conductive material layer 80 may be always kept constant, or may be changed depending on the fluid temperature or the temperature of the conductive material layer 77.

Example 8. FIG. 18A is a plan view of a semiconductor type flow rate detecting device according to an embodiment of the present invention. FIG. 18B is a partially enlarged view showing an enlarged main part of the semiconductor type flow rate detecting device in FIG. The thin plate 78 shown in the seventh embodiment is designed to have a very small thickness of 2 to 3 microns in order to reduce the amount of heat conduction to the semiconductor substrate 76 and to reduce the heat capacity of the thin plate 78. For this reason, it is particularly weak against the force in the vertical direction, and there is a risk of breakage. Therefore, the flow rate detection chip 82 of the present embodiment
Then, the mechanical strength of the thin plate 83 is improved by providing the reinforcing beams 84 formed at the both ends of the thin plate 83 so as to intersect the thin plate 83 at a right angle.

When the amount of heat transferred to the semiconductor substrate via the reinforcing beam 84 becomes a problem, as shown in FIG. 18B, the total width of the supporting beam 86 of the thin plate 83 and the reinforcing beam 84 is the thin plate. If the width is equal to the width of the semiconductor substrate 83,
Although the amount of heat conduction to 5 does not change, the mechanical strength is improved by increasing the number of support beams.

FIG. 19 is a plan view of a semiconductor type flow rate detecting device according to another embodiment of the present invention of claim 14. In this embodiment, the thin plate 88 is bridged by four support beams 89, and a reinforcing beam 90 is formed so as to intersect the support beams 89 at an acute angle. Also in this case, if the widths of the supporting beam 89 and the reinforcing beam 90 are adjusted as in the above-described example,
Only the strength can be improved without changing the amount of heat conduction to the semiconductor substrate 91.

Next, an embodiment of a method of attaching the flow rate detecting chip will be described. 20 (a) is a front view showing a method of mounting the semiconductor type flow rate detecting device according to an embodiment of the invention of claim 15 and FIG. 20 (b) is a side view of the semiconductor type flow rate detecting device of FIG. 20 (a). It is a figure. Flow rate detection chip 9
3 is a package 95 in which a lead frame 94 is molded
The package 95 is attached to the die pad frame 9 in order to improve the mounting accuracy at the time of adhesion.
6 (a U-shaped support) is provided. The die pad frame 96 is U-shaped, and both ends of the flow rate detecting chip 93 are adhered to parallel parallel pieces 97 of the die pad frame 96. Further, a vertical piece 98 connecting the parallel pieces 97 is installed in the flow path so as to come to the downstream side of the flow rate detection chip 93. By using this die pad frame 96, the flow rate detection chip 93 can be fixed horizontally with high accuracy, and as a result, variation in attachment of the flow rate detection chip 93 can be reduced and variation in characteristics can be suppressed.

Next, the silicide material used for the conductive material layer will be described. FIG. 21 is a table showing the thermal conductivity and the temperature coefficient of resistance of a conductive material layer of a semiconductor type flow rate detector according to an embodiment of the invention of claim 16. MoSi ₂ , WSi ₂ , T which is a compound (silicide) of metal and silicon
i Si _2, TaSi ₂ is, Pt has been used as a conventional electrically conductive material layer, Fe, very small compared thermal conductivity to Ni, Using these suicide material as a heating element, the heat loss due to heat conduction It can be reduced, and the characteristics as a sensor can be improved. Further, the temperature coefficient of resistance is almost the same as that of a conventional single metal, and is a value that can be sufficiently used as a heating element of a flow sensor.

Another advantage of using the silicide material as the conductive material layer of the flow sensor is that the existing semiconductor process can be applied as it is. Current,
Mo, W, Ti, and
Silicon compounds of refractory metals such as Ta tend to be often used. This is because these silicon compounds have excellent interfacial stability with silicon. For example,
As a gate electrode wiring material of a MOS type LSI, a silicon compound of a refractory metal has already been often used. That is,
If a MOS process line is used, the conductive material layer of the flow sensor can be formed simply by changing the mask. Thus, MoSi ₂ , WSi ₂ , TiSi ₂ , T
The use of aSi ₂ for the conductive material layer is also advantageous in terms of mass productivity.

Next, the control circuit of the heating element made of the conductive material layer will be described. FIG. 22 is a circuit diagram showing the control circuit of the heating element. In the figure, the heating resistor 120, the precision resistor 121, the fluid temperature detecting element 122, and the plurality of bridge resistors 123 form a bridge circuit.
The resistance value of these bridge resistors 123 is
The temperature of 0 is set to be always higher than the temperature of the fluid temperature detecting element 122 by a constant temperature.

In this circuit, when the heating resistor 120 is cooled by the fluid and its temperature drops, an imbalance occurs in the bridge circuit. When a potential difference occurs between the input terminals of the differential amplifier 124, the differential amplifier 124 and the transistor 126
By the function of, the heating resistor 120 is supplied with more current, and the temperature of the heating resistor 120 rises. This increase in supply current continues until the bridge circuit reaches equilibrium, but the supply current to the heating resistor 120 is changed to the precision resistor 121.
Is output from the output terminal 125 as the voltage across both ends to detect the fluid flow rate. In this circuit, the heating resistor 120 plays the two roles of the heating element and the temperature detecting element of the heating element at the same time, and is therefore called a direct heating circuit.

FIG. 23 shows another example of the heating element control circuit. In this example, in addition to the heating resistor 120, this heating resistor 1
A heating element temperature detecting element 128 for detecting the temperature of 20 is provided. When the heating resistor 120 is cooled by the fluid and its temperature drops, the temperature of the heating element temperature detecting element 128 also drops, resulting in imbalance in the bridge circuit and a potential difference at the input terminals of the differential amplifier 124. Therefore, due to the functions of the differential amplifier 124 and the transistor 126, a larger amount of current is supplied to the heating resistor 120, the temperature of the heating resistor 120 rises, and the heating element temperature detection element 12
The temperature of 8 also rises.

The increase of the current supplied to the heating resistor 120 is continued until the bridge circuit reaches the equilibrium. The current supplied to the heating resistor 120 is output from the output terminal 125 as the voltage across the heating resistor 120 itself to detect the fluid flow rate. In this circuit, the heat generating element 120 and the heat generating element temperature detecting element 128 are separated from each other and arranged close to each other, and are therefore called an indirectly heated circuit.

[0088]

As described above, according to the first aspect of the invention, the convex portion is located at the bottom of the concave portion formed in the semiconductor substrate, and the tip is separated from the thin plate forming the conductive material layer. Therefore, there is an effect that the mechanical strength of the thin plate can be improved, and the thin plate can be less likely to be broken during dicing or during the assembly process.

According to the second aspect of the present invention, in the process step of forming the concave portion, the tip end is tapered toward the thin plate by the anisotropic etching technique, and the convex portion whose tip is separated from the thin plate is formed into the concave portion. Since it is configured to be formed at the bottom of the sheet, there is an effect that it is possible to improve the mechanical strength of the thin plate and prevent breakage during dicing or during the assembly process.

According to the third aspect of the present invention, the through hole connects the recess of the semiconductor substrate and the back surface of the semiconductor substrate, and the low pressure holding means applies a pressure generated in the opening of the through hole on the back surface side of the semiconductor substrate to the semiconductor. Since the pressure is lower than the pressure generated in the opening on the front surface side of the substrate, the heat transfer from the back surface of the heating element can be promoted, and the responsiveness is improved.

According to the invention of claim 4, the streamlined support which is a low pressure holding means has a wide portion and a narrow portion, the passage is formed in the streamlined support, and one opening is formed. Since it is configured so that it is connected to the opening on the back surface of the semiconductor substrate and the other opening is positioned wider than the position of the semiconductor substrate, it is possible to promote heat transfer from the back surface of the heating element and improve the responsiveness. It has the effect of improving.

According to the invention of claim 5, since the back surface of the semiconductor substrate is held by the support which is the low pressure holding means so that the back surface of the semiconductor substrate forms an acute angle with the flow direction of the fluid, Can promote the heat transfer of
This has the effect of improving responsiveness.

According to the sixth aspect of the invention, since at least one step portion which is the low pressure holding means is provided on the back surface of the semiconductor substrate, heat transfer from the back surface of the heating element can be promoted, This has the effect of improving responsiveness.

According to the invention of claim 7, since the second recess is configured to surround the periphery of the recess formed in the semiconductor substrate, heat transfer from the heating element to the substrate is suppressed, and the sensitivity of the sensor and Responsiveness is improved.

According to the invention of claim 8, a pair of thin plates supported by the semiconductor substrate by at least one support portion are located in both openings of the fluid passage that penetrates the semiconductor substrate, and a pair of conductive material layers are provided. Since it is configured to be formed on at least one of the thin plates, it is possible to suppress variations in individual sensors and reduce variations in characteristics. Further, if one of the thin plates is used as a dust adhesion preventing material or a fluid temperature detecting element, the effect of reducing the cost can be obtained.

According to the invention of claim 9, a step of forming a first thin plate having a conductive material layer on one surface of the semiconductor substrate and supported by the semiconductor substrate by at least one supporting portion, The step of forming a second thin plate having a conductive material layer on the other surface of the semiconductor substrate and supported by the semiconductor substrate by at least one support portion; Since the semiconductor substrate located immediately below the thin plate and the second thin plate is deleted and a fluid passage that penetrates the semiconductor substrate is formed, variations in individual sensors are suppressed and variations in characteristics are also reduced. It is possible to obtain the effect that the cost can be further reduced.

According to the invention of claim 10, at least 1
A step of forming a first thin plate having a conductive material layer on one surface of the semiconductor substrate, which is supported by the first semiconductor substrate by two supporting portions, and an anisotropic etching technique is provided immediately below the first thin plate. Forming a through hole in the second semiconductor substrate, and supporting the second semiconductor substrate by at least one supporting portion,
By a step of forming a second thin plate having a conductive material layer on one surface of the semiconductor substrate and an anisotropic etching technique,
Since the step of forming the through hole directly below the second thin plate and the step of attaching the back surfaces of the semiconductor substrates to each other so that the through holes are aligned with each other are suppressed, variations in individual sensors are suppressed, and characteristics are reduced. It is possible to obtain the effect that the variation of can be reduced and the cost can be reduced.

According to the invention of claim 11, at least 1
Since the thin plate having the conductive material layer supported on the semiconductor substrate by the two supporting portions is provided in the narrowest part of the fluid passage having the narrowest central part formed so as to penetrate the semiconductor substrate, the heating element is provided. The effect of being able to promote heat transfer from the substrate and improving sensitivity and responsiveness is obtained.

According to the invention of claim 12, at least 1
Forming a thin plate having a conductive material layer on one surface of the first semiconductor substrate, which is supported by the first supporting portion by one supporting portion, and anisotropy from the other surface of the first semiconductor substrate. Etching is performed to form a tapered through hole that spreads downwardly just below the thin plate, and anisotropic etching is performed from one surface of the second semiconductor substrate.
Forming a tapered through hole narrowing downward from one surface of the semiconductor substrate, and the first semiconductor substrate and the second semiconductor substrate so that the surfaces having small opening areas of the through hole coincide with each other. And the step of attaching the back surfaces to each other are provided, heat transfer from the heating element can be promoted, and the effect of improving sensitivity and responsiveness can be obtained.

According to the thirteenth aspect of the invention, the second conductive material layer is formed near the base end of the supporting portion of the thin plate which is located above the recess and has the conductive material layer formed therein. In addition, the amount of heat transferred to the semiconductor substrate can be reduced and the response can be improved.

According to the fourteenth aspect of the present invention, since the reinforcing beam is formed near the base end of the supporting portion so as to intersect with the supporting portion and configured to reinforce the supporting portion, the mechanical strength of the thin plate is increased. The effect is obtained.

According to the fifteenth aspect of the present invention, the U-shaped support body fixed by the resin mold fixes both ends of the semiconductor substrate. Therefore, variation in attachment at the time of adhering the semiconductor substrate can be reduced, and characteristics can be reduced. Has the effect of suppressing variations in

According to the sixteenth aspect of the invention, since the conductive material layer uses a silicon compound of a metal such as WSi ₂ , TiSi _2, etc., the existing semiconductor process can be applied and mass production is facilitated. is there.

[Brief description of drawings]

FIG. 1 (a) is a plan view showing a semiconductor type flow rate detecting device according to an embodiment of the present invention, and FIG. 1 (b) is FIG.
It is sectional drawing which shows the state when (a) is cut | disconnected by AA.

FIG. 2 is a cross-sectional view showing a manufacturing process of the flow rate detection chip 20 according to the first embodiment.

FIG. 3 is a sectional view showing a semiconductor type flow rate detecting device according to an embodiment of the invention of claim 3;

FIG. 4 is a cross-sectional view showing an embodiment of the low pressure holding means in claim 4.

FIG. 5A is a plan view showing a state in which the streamlined support is attached to the intake air pipe of the engine, and FIG.
[Fig. 4] is a front view showing a state in which the streamlined support is attached inside the intake air pipe of the engine.

FIG. 6 is a cross-sectional view showing an embodiment of the low pressure holding means in claim 5.

7A is an enlarged perspective view showing an example of a support body that holds the back surface of the flow rate detection chip at an acute angle with respect to the fluid flow direction, and FIG. 7B is a support body of FIG. 7A. Is a plan view showing the state when the is installed in the intake air pipe of the engine,
FIG. 7C is a front view showing a state in which the support of FIG. 7A is mounted in the intake air pipe of the engine.

8A is an enlarged perspective view showing an example of a support body that holds the back surface of the flow rate detection chip at an acute angle with respect to the fluid flow direction, and FIG. 8B is a support body of FIG. 8A. Is a plan view showing the state when the is installed in the intake air pipe of the engine,
FIG. 8C is a front view showing a state in which the support body of FIG. 8A is mounted in the intake air pipe of the engine.

FIG. 9 is a front view showing another embodiment of the low pressure holding means according to claim 6;

10A is a plan view showing a semiconductor type flow rate detecting device according to an embodiment of the invention of claim 7, and FIG. 10B is a plan view of the semiconductor type flow rate detecting device according to an embodiment of the invention of claim 7; It is sectional drawing when it cut | disconnects by the AA line of FIG.10 (a).

FIG. 11 is a sectional view showing a semiconductor type flow rate detecting device according to an embodiment of the invention of claim 8;

FIG. 12 is a sectional view showing a semiconductor type flow rate detecting device according to an embodiment of the present invention.

FIG. 13 is a cross-sectional view showing the method of manufacturing the semiconductor type flow rate detecting device according to the embodiment of the invention of claim 9;

FIG. 14 is a cross-sectional view showing the method of manufacturing the semiconductor type flow rate detector according to the embodiment of the invention of claim 10;

FIG. 15 is a sectional view of a flow rate detecting chip according to an embodiment of the present invention.

FIG. 16 is a cross-sectional view showing the method of manufacturing the semiconductor type flow rate detector according to the embodiment of the invention of claim 12;

17A is a plan view of a semiconductor type flow rate detecting device according to an embodiment of the present invention of claim 13; FIG. 17B is a plan view of the semiconductor type flow rate detecting device according to an example of the present invention of claim 13; It is sectional drawing when it cut | disconnects by the BB line.

18 (a) is a plan view of a semiconductor type flow rate detecting device according to an embodiment of the present invention of claim 14, and FIG. 18 (b) is an enlarged view of a main part of the semiconductor type flow rate detecting device in FIG. 18 (a). FIG.

FIG. 19 is a plan view of a semiconductor type flow rate detector according to another embodiment of the present invention.

20 (a) is a front view showing a method of mounting the semiconductor type flow rate detecting device according to an embodiment of the invention of claim 15, and FIG. 20 (b) is a side view of the semiconductor type flow rate detecting device of FIG. 20 (a). It is a figure.

FIG. 21 is a table showing the thermal conductivity and the temperature coefficient of resistance of a conductive material layer of a semiconductor type flow rate detector according to an embodiment of the invention of claim 16;

FIG. 22 is a circuit diagram showing an example of a heating element control circuit.

FIG. 23 is a circuit diagram showing another example of the control circuit of the heating element.

FIG. 24 is a sectional view showing an example of a conventional semiconductor type flow rate detecting device.

FIG. 25 is a perspective view showing another example of a conventional semiconductor type flow rate detecting device.

[Explanation of symbols]

21, 31, 44, 51, 61, 76, 85, 91 Semiconductor substrate, 22, 32, 45, 52, 63, 78, 83
Thin plate, 23, 33, 46, 53, 79 recess, 24,
34,77 heating element (conductive material layer), 25 convex portions, 2
6, 54, 86 support beam (support portion), 35, 47, 65
Through hole, 36 Streamlined support (low pressure holding means), 38
Passage (low pressure holding means), 41 package (low pressure holding means), 42 holder (low pressure holding means), 48
Step (low pressure holding means), 55 Second recess, 62
Fluid passage, 80 second conductive material layer, 84 reinforcing beam, 9
6 Die pad frame (U-shaped support).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsukasa Matsuura 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation

Claims (16)

[Claims] 1. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one supporting portion and having a conductive material layer formed therein. A semiconductor type flow rate detecting device, wherein a convex portion whose tip is separated from the thin plate is provided at a bottom portion of the concave portion. 2. A method for manufacturing a semiconductor type flow rate detecting device, comprising: a step of forming a thin plate having a conductive material layer on a semiconductor substrate; and a step of forming a recess directly below the thin plate,
At the process step of forming the concave portion, the tip becomes thinner toward the thin plate by the anisotropic etching technique,
A method of manufacturing a semiconductor type flow rate detecting device, characterized in that a convex portion whose tip is separated from the thin plate is formed on a bottom portion of the concave portion. 3. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one support part and having a conductive material layer formed therein. In the flow rate detection device, the pressure generated in the through hole connecting the concave portion of the semiconductor substrate and the back surface of the semiconductor substrate and the pressure generated in the opening portion of the through hole on the back surface side of the semiconductor substrate is set on the front surface side of the semiconductor substrate A semiconductor type flow rate detecting device comprising a low pressure holding means for keeping the pressure lower than the pressure generated in the section. 4. The low-pressure-holding means is formed in the streamline-type support body having a wide portion and a narrow-width portion, and one opening is formed on the rear surface of the semiconductor substrate. 4. The semiconductor type flow rate detection device according to claim 3, further comprising a passage which is connected to the other opening and is wider than the position of the semiconductor substrate. 5. The semiconductor type flow rate detection device according to claim 3, wherein the low pressure holding means is a support body that holds the back surface of the semiconductor substrate at an acute angle with respect to the flow direction of the fluid. apparatus. 6. The semiconductor type flow rate detection device according to claim 3, wherein the low pressure holding means is a step portion provided on the back surface of the semiconductor substrate. 7. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one supporting portion and having a conductive material layer formed therein. A semiconductor type flow rate detection device comprising a second recessed portion provided so as to surround the periphery of the recessed portion. 8. A pair of thin plates positioned at both openings of the fluid passage that penetrates the semiconductor substrate and the fluid passage, and supported by the semiconductor substrate by at least one support portion; 1. A semiconductor type flow rate detection device comprising a conductive material layer formed as one. 9. A first thin plate having a conductive material layer on one surface of a semiconductor substrate, the first thin plate being supported by the semiconductor substrate by at least one supporting portion, and at the other surface of the semiconductor substrate, A step of forming a second thin plate having a conductive material layer and supported by the at least one supporting portion on the semiconductor substrate; and an anisotropic etching technique to directly below the first thin plate and the second thin plate. 9. The method for manufacturing a semiconductor type flow rate detecting device according to claim 8, further comprising the step of removing the semiconductor substrate located in the step of forming a fluid passage. 10. First by at least one support
Forming a first thin plate having a conductive material layer on one surface of the first semiconductor substrate and supported by the semiconductor substrate, and a through hole is formed directly below the first thin plate by an anisotropic etching technique. Forming a second thin plate having a conductive material layer on one surface of the second semiconductor substrate, the second thin plate being supported by at least one supporting portion on the second semiconductor substrate. With the etching technique, the second
9. A step of forming a through hole directly below the thin plate of 1), and a step of bonding the back surfaces of the first and second semiconductor substrates to each other so that the through holes coincide with each other. A method for manufacturing the semiconductor type flow rate detecting device according to. 11. A fluid passage that penetrates a semiconductor substrate and is narrowest in the central portion of the semiconductor substrate, and is located in the narrowest portion of the fluid passage, and is supported by the semiconductor substrate by at least one support portion. And a conductive material layer formed inside the thin plate. 12. A thin plate having a conductive material layer, which is supported by the semiconductor substrate by at least one supporting portion, and which is a first plate.
A step of forming on one surface of the semiconductor substrate, and a step of performing anisotropic etching from the other surface of the first semiconductor substrate to form a tapered through hole that spreads downwardly just below the thin plate, A step of performing anisotropic etching from one surface of the second semiconductor substrate to form a tapered through hole narrowing downward from one surface of the second semiconductor substrate, and a surface having a small opening area of the through hole. The above first so that they match each other
12. The step of adhering the back surfaces of the semiconductor substrate and the second semiconductor substrate to each other is included.
A method for manufacturing the semiconductor type flow rate detecting device according to. 13. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one supporting portion and having a conductive material layer formed therein. A semiconductor type flow rate detection device, comprising a second conductive material layer near the base end of the support portion. 14. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one supporting portion and having a conductive material layer formed therein. The semiconductor type flow rate detection device according to claim 1, further comprising a reinforcing beam which is formed near the base end of the support part so as to intersect with the support part and which reinforces the support part. 15. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one supporting portion and having a conductive material layer formed therein. A semiconductor type flow rate detecting device, wherein both ends of the semiconductor substrate are fixed to a U-shaped support body fixed by a resin mold. 16. A semiconductor having a recess formed in a semiconductor substrate, and a thin plate located above the recess and supported by the semiconductor substrate by at least one supporting portion and having a conductive material layer formed therein. A semiconductor type flow rate detecting device, wherein a silicon compound of a metal such as WSi ₂ , TiSi ₂ is used as the conductive material layer.