JP2000111379A - Flow-rate detecting device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide flow-rate detecting device in which an insulating film, a thermosensitive resistor and a protective film are formed sequentially on a substrate, in which a continuity hole is formed in the protective film situated in the terminal region of the thermosensitive resistor, in which an electrode pad is installed in the continuity hole by using stress relaxation and in which the electrode pad and the thermosensitive resistor are connected by increasing their close contact property. SOLUTION: An insulating film 6 is formed on the surface of a substrate 5. An upstream-side resistor, a heater resistor 8 and a downstream-side resistor are arranged and installed in parallel on the insulating film 6. Continuity holes 27 are formed in positions which are situated in terminal regions 13 of the heater resistor 8 out of a protective film 26. A stress relaxation layer 33 is formed between the terminal regions 13 bonded through the continuity holes 27 and electrode pads 30. The terminal regions 13 are pressed to the side of the insulating film 6 so as to be fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate detecting device suitable for detecting an intake air amount of, for example, an automobile engine and a method of manufacturing the same, and more particularly to a flow rate detecting device formed by a semiconductor manufacturing technique such as etching. The present invention relates to a flow rate detection device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, in an automobile engine or the like, in order to calculate the amount of fuel to be injected into a fuel chamber of an engine body, a flow rate or a flow rate (hereinafter referred to as a flow rate) of intake air is measured by a flow rate detecting device provided in an intake pipe of the engine. , Flow rate), and the intake air amount of the engine is calculated based on the detection result.

[0003] Such a conventional flow rate detecting device comprises a substrate, an insulating film provided on the substrate, and a temperature-sensitive resistor provided on the insulating film (for example, And JP-A-62-44627.

In this case, in the prior art, a temperature-sensitive resistor made of a temperature-sensitive resistance material such as platinum is formed as a wiring pattern on a substrate formed of a silicon material or the like by etching. And the temperature-sensitive resistor is
It is connected to an externally provided detection circuit for detecting the resistance value.

Further, since the substrate is mounted in a state exposed in the intake pipe of the engine, the temperature-sensitive resistor on the substrate comes into contact with intake air flowing through the intake pipe toward the engine body. During the operation of the engine, an electric current is supplied from an external detection circuit to the temperature-sensitive resistor to cause the temperature-sensitive resistor to generate heat, and the temperature-sensitive resistor is generated according to the flow rate of the fluid flowing along the substrate. Cooled.

As a result, the resistance value of the temperature-sensitive resistor changes according to the flow rate of the intake air. Therefore, the detection circuit detects the change in the resistance value as a voltage signal, and the engine detects the change in the resistance value based on the detection result. Is calculated.

In general, in order to fix a temperature-sensitive resistor on a substrate, an insulating film made of a silicon oxide film or a silicon nitride film formed on the surface of the substrate; A protective film made of a silicon oxide film and a silicon nitride film is provided similarly to the insulating film, and the temperature-sensitive resistor is fixed on the substrate by sandwiching the temperature-sensitive resistor between the insulating film and the protective film. I was Furthermore, in order to increase the bonding strength between the insulating film and the temperature-sensitive resistor, and between the temperature-sensitive resistor and the protective film, the distance between the insulating film and the temperature-sensitive resistor and between the temperature-sensitive resistor and the protective film are increased. And an adhesion layer formed of a metal oxide.

In the flow rate detecting device according to the prior art described above, an insulating film, a temperature-sensitive resistor, and a protective film are formed in this order on the substrate surface by etching, CVD, RIE, etc. In order to set the temperature resistor to a predetermined resistance value and temperature coefficient, heat treatment was performed at about 800 to 1000 ° C. in an atmosphere of an inert gas (eg, argon), nitrogen gas, or the like.

Therefore, during this heat treatment step, the adhesion layers formed above and below the temperature-sensitive resistor dissolve into the temperature-sensitive resistor to form a compound, and the composition of the temperature-sensitive resistor changes. And the temperature coefficient may vary. However, in this case, since the temperature coefficient of the temperature sensitive resistor changes for each product, there is a problem that the yield is deteriorated, and the productivity and reliability are reduced.

On the other hand, in order to solve this problem, the temperature-sensitive resistor is sandwiched between the protective film and the insulating film without using the adhesion layer. There is also another conventional technique in which peeling is suppressed (for example, Japanese Patent Application Laid-Open No. 8-271308).

In another conventional technique, a terminal area is provided on the temperature-sensitive resistor in order to derive a signal detected by the temperature-sensitive resistor to the outside, and a protective film is provided on a portion corresponding to the terminal area. A conduction hole is formed, and an electrode pad is provided on the protective film, the electrode pad being connected to a terminal region of the temperature-sensitive resistor in a state where the conduction hole is closed.

[0012]

However, in the other prior art, the processing temperature and the coefficient of thermal expansion during the process of forming both members between the terminal region of the temperature-sensitive resistor and the electrode pad connected to the terminal region. Therefore, in the terminal region, a difference occurs in the film stress between the temperature-sensitive resistor and the electrode pad. For this reason, between the insulating film having low adhesiveness and the temperature-sensitive resistor, the temperature-sensitive resistor is easily lifted from the insulating film by acting to release the difference in the film stress. Due to the lifting, the temperature-sensitive resistor (terminal region) is easily peeled off from the insulating film, and there is a possibility that the electrode pad and the temperature-sensitive resistor may have a poor electrical contact. There is a problem that it reduces.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention reduces a difference in film stress between a temperature-sensitive resistor and an electrode pad generated in a terminal region by a stress relieving layer, It is an object of the present invention to provide a flow rate detection device capable of preventing a terminal region from floating from an insulating film and improving reliability and life of the entire device.

[0014]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a substrate, an insulating film formed on the surface of the substrate, and a thermosensitive layer provided on the insulating film are provided. In a flow rate detection device comprising a resistor and a protective film provided to cover the surfaces of the temperature-sensitive resistor and the insulating film, the temperature-sensitive resistor is externally connected to the protective film. A conductive hole for exposing a portion corresponding to the terminal region is provided, and an electrode pad connected to the terminal region of the temperature-sensitive resistor in a state where the conductive hole is closed is provided on the protective film. A stress relief layer is provided between the terminal region of the thermal resistor and a stress relaxation layer for reducing a difference in film stress between the temperature sensitive resistor and the electrode pad generated in the terminal region.

[0015] With this configuration, the stress relaxation layer formed between the terminal region of the temperature-sensitive resistor and the electrode pad has a difference in thermal expansion coefficient between the temperature-sensitive resistor and the electrode pad. And acts to alleviate the difference in film stress generated due to the different processing temperatures.

[0016] Thus, the terminal region can also prevent the temperature-sensitive resistor (terminal region) having a low adhesive force from rising from the insulating film in an attempt to release the film stress. The terminal region can be fixed to the insulating film, and the electrode pad can be connected to the terminal region with improved adhesion.

According to a second aspect of the present invention, the stress relaxation layer is made of a metal compound obtained by combining the metal material of the temperature-sensitive resistor and the metal material of the electrode pad.

With this configuration, when the stress relaxation layer is formed by using, for example, a sputtering method, the film stress of the stress relaxation layer can be adjusted. The difference in film stress generated between the resistor and the electrode pad can be sufficiently reduced by the stress relaxation layer, and the terminal region can be fixed to the insulating film.

According to a third aspect of the present invention, the insulating film and the protective film are formed of any one of a silicon nitride film, a silicon oxide film, and a multilayer film composed of silicon nitride and silicon oxide, and the temperature-sensitive resistor is formed of platinum. The electrode pad is formed of aluminum, and the stress relaxation layer is formed of a metal compound containing aluminum and platinum.

With this configuration, for example, when the insulating film and the protective film are formed of the same silicon nitride film, the thermal expansion coefficients of the insulating film and the protective film can be made substantially equal, and the insulating film and the protective film can be formed. Can be joined in a state where the adhesion is enhanced.

Further, the temperature-sensitive resistor is made of platinum, the electrode pad is made of aluminum, and the stress relaxation layer is made of a metal compound containing aluminum and platinum as a film stress between platinum and aluminum. The difference in the film stress to be released can be reduced by the stress relaxation layer having the film stress between platinum and aluminum, and the terminal region can be fixed to the insulating film.

According to the fourth aspect of the present invention, the temperature-sensitive resistor is provided on the substrate by the first temperature-sensitive resistor, the heater resistor, and the second resistor.
The first temperature-sensitive resistor is arranged in parallel on one side in the width direction and the second temperature-sensitive resistor is arranged in parallel on the other side in the width direction across the heater resistor. is there.

According to the fifth aspect of the present invention, the heater resistor is provided on the positive wiring region provided with a gap in the longitudinal direction of the substrate.
A negative-side wiring region, a heater region provided at a portion connecting one end of the positive-side wiring region and the negative-side wiring region in the longitudinal direction, and a length of the positive-side wiring region and the negative-side wiring region. A terminal area provided on the other end side in the direction,
The first and second temperature-sensitive resistors are provided with a positive wiring region and a negative wiring region provided with a gap in the length direction of the substrate, and a lengthwise direction between the positive wiring region and the negative wiring region. It is constituted by a detection region provided at a portion connecting one end side, and terminal regions provided at the other end side in the length direction of the positive side wiring region and the negative side wiring region.

As described above, by disposing the first temperature-sensitive resistor and the second temperature-sensitive resistor in parallel in the width direction with the heater resistor interposed therebetween, the fluid flows along the substrate in the width direction. When flowing from the side, the first temperature-sensitive resistor located on the upstream side is cooled, and the second temperature-sensitive resistor located on the downstream side is heated by receiving the heat of the heater resistor. Then, the flow direction and the flow rate (flow velocity) of the fluid can be detected from the change in the resistance value of the first and second temperature-sensitive resistors.

According to a sixth aspect of the present invention, an insulating film is formed on a surface of a substrate made of a silicon material, a temperature-sensitive resistor is formed on the insulating film, and the surface of the temperature-sensitive resistor and the insulating film are formed. A protective film is formed so as to cover the surface and the protective film, a conductive hole is formed in the protective film to expose a portion corresponding to a terminal region for connecting the temperature-sensitive resistor to the outside, and the conductive hole is formed on the protective film. An electrode pad is formed in a closed state, and a stress relaxation layer is formed by a metal compound generated at an interface between the electrode pad and the terminal region by applying heat while the electrode pad is in contact with the terminal region. It is in.

In this case, by applying heat while the electrode pad is in contact with the terminal region through the conduction hole, a metal compound generated at the interface between the electrode pad and the terminal region is formed. It becomes a stress relaxation layer having a film stress between the pad and the temperature-sensitive resistor. Then, the electrode pad and the terminal region can be connected to each other with the stress relaxation layer in a state where the adhesion is enhanced. Accordingly, even when the temperature-sensitive resistor (terminal region) corresponding to the conduction hole releases the film stress that tends to rise from the insulating film, the temperature-sensitive resistor has a film stress between the electrode pad and the temperature-sensitive resistor. The stress relaxation layer alleviates the difference in film stress, and can fix the terminal region to the insulating film.

According to a seventh aspect of the present invention, an insulating film is formed on a surface of a substrate made of a silicon material, a temperature-sensitive resistor is formed on the insulating film, and the surface of the temperature-sensitive resistor and the insulating film are formed. A protective film is formed so as to cover the surface and a conductive hole is formed in the protective film to expose a portion corresponding to a terminal region for connecting the temperature-sensitive resistor to the outside. A metal compound obtained by combining the metal material of the body and the metal material of the electrode pad is deposited to form a stress relaxation layer, and a terminal area is formed on the protective film via the stress relaxation layer with the conduction hole closed. In that an electrode pad for connection with the electrode is formed.

As described above, when the stress relieving layer is formed by vapor deposition, for example, when the sputtering method is used, the film stress of the stress relieving layer can be adjusted. A stress relieving layer having a film stress between the pad and the temperature-sensitive resistor optimally mitigates a difference in the film stress, and can fix the terminal region to the insulating film.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a flow rate detecting device according to the present invention will be described below in detail with reference to FIGS.

First, a first embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 denotes a cylinder serving as a flow path through which a fluid to be measured flows. The cylinder 1 is connected in the middle of an intake pipe (not shown) of the engine. During operation of the engine, intake air drawn into the combustion chamber of the engine body from the outside through the intake pipe flows in the cylinder 1 in the direction of arrow A.

Reference numeral 2 denotes a circuit casing provided on the outer surface of the cylindrical body 1. In the circuit casing 2, the flow rate of intake air flowing through the cylindrical body 1 is determined based on a detection signal output from a flow rate detecting device 4 described later. A detection circuit (not shown) for detection is housed.

Reference numeral 3 denotes a support provided on the cylinder 1 for supporting a flow rate detecting device 4 described later. The support 3 has a base end attached to the circuit casing 2 and a tip end protruding into the cylinder 1. At the same time, a substrate 5 to be described later is attached to the front end side. Further, the support 3 is provided with a wiring portion (not shown) for connecting the substrate 5 side and the detection circuit in the circuit casing 2 and the like.

Reference numeral 4 denotes a flow rate detecting device.
A substrate 5 described below, an insulating film 6 formed on the surface of the substrate 5, a heater resistor 8 provided on the insulating film 6,
The upstream resistor 14, the downstream resistor 20, and the resistor 8,
A protection film 26 is provided to cover the surfaces of the insulating films 14 and 20 and the surface of the insulating film 6.

Reference numeral 5 denotes a substrate serving as a base of the flow rate detecting device 4.
The substrate 5 is formed in a plate shape by a silicon plate.
An insulating film 6 is formed on the surface of the substrate 5.
Here, the insulating film 6 is formed on the surface of the substrate 5 made of a silicon plate by a method such as a thermal oxidation method or a CVD method using silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ O ₄ ).
It is formed with a thickness of about [μm].

Reference numeral 7 denotes a concave portion formed by performing an etching process or the like from the back side of the substrate 5. The concave portion 7 reaches the position of the insulating film 6 from the back side, and the bottom of the concave portion 7 is formed. The surface of the substrate 5 corresponding to the
Heater region 12, detection region 18 of upstream resistor 14,
The detection regions 24 of the downstream resistor 20 are provided respectively.

Numeral 8 denotes a heater resistor provided at an intermediate portion of the substrate 5 in the width direction. The heater resistor 8 has a thickness of about 0.5 μm made of a temperature-sensitive resistance material such as platinum. Is formed. As shown in FIG. 3, the heater resistor 8 includes a trapezoidal positive wiring region 9 provided on the substrate 5 and a gap 10 in the length direction of the positive wiring region 9 and the substrate 5.
A negative-side wiring region 11 having a trapezoidal shape, and a heater region 12 as a detection region provided at a portion connecting one end of the positive-side wiring region 9 and one end of the negative-side wiring region 11 in the longitudinal direction. And the terminal regions 13 provided on the other end side in the length direction of the positive wiring region 9 and the negative wiring region 11. Further, the positive side wiring region 9 and the negative side wiring region 11 are formed with a contact area larger than a contact area between the heater region 12 and the substrate 5.

Reference numeral 14 denotes an upstream resistor serving as a first temperature-sensitive resistor provided on one side in the width direction of the substrate 5. The upstream resistor 14 is made of the same platinum material as the heater resistor 8. The upstream-side resistor 14 is provided with a substantially trapezoidal positive wiring region 15 provided on the substrate 5 and a gap 16 in the length direction of the positive wiring region 15 and the substrate 5. A substantially trapezoidal negative wiring region 17;
A detection area 18 provided at a portion connecting one end in the length direction, and terminal areas 19 and 19 provided at the other end in the length direction of the wiring areas 15 and 17. It is configured. The wiring regions 15 and 17 are formed with a contact area larger than the contact area between the detection region 18 and the substrate 5.

Reference numeral 20 denotes a downstream resistor as a second temperature-sensitive resistor provided on the other side of the substrate 5 in the width direction. The downstream resistor 20 includes the heater resistor 8 and the upstream resistor. Body 14
The downstream resistor 20 is formed of the same platinum material as
Is a substantially trapezoidal positive-side wiring region 21 provided on the substrate 5.
And a gap 22 in the length direction of the substrate 5 and the positive side wiring region 21.
And a substantially trapezoidal negative-side wiring region 23 provided at one end of the wiring regions 21 and 23 in the longitudinal direction.
It comprises a detection region 24 in the shape of a letter, and terminal regions 25, 25 provided on the other end side in the length direction of the wiring regions 21, 23. The wiring regions 21 and 23 are formed with a contact area larger than the contact area between the detection region 24 and the substrate 5.

The electrical resistance of the positive wiring region 9 and the negative wiring region 11 of the heater resistor 8 having a large contact area with the substrate 5 is smaller than that of the heater region 12. The wiring regions 9 and 11 are configured as connecting members for connecting the heater region 12 and the outside.
Further, the wiring regions 15 and 17 of the upstream resistor 14 and the wiring regions 21 and 23 of the downstream resistor 20 are also the detection regions 18 and 23.
Since the electric resistance is smaller than that of the detection regions 18, 24,
It is configured as a connecting member for connecting the outside and the outside.

Reference numeral 26 denotes a protective film provided so as to cover the surfaces of the heater resistor 8 and the insulating film 6. The protective film 26 is made of silicon oxide (SiO.
₂ ), formed of silicon nitride (Si ₃ O ₄ ), and the protection film 26 protects the heater resistor 8. As described above, the resistors 8, 14, and 20 are fixed between the protective film 26 and the insulating film 6 in a state of increasing adhesion.

Reference numerals 27, 27 denote conduction holes on the heater resistor 8 side, and each of the conduction holes 27 is a terminal region 13,
The portion corresponding to 13 is exposed to the outside, and these conduction holes 27 are closed by electrode pads 30 described later.

Reference numerals 28, 28 denote conduction holes on the upstream resistor 14 side, and each of the conduction holes 28 is a terminal region 1 of the upstream resistor 14.
Portions corresponding to 9 and 19 are exposed to the outside, and these conduction holes 28 are closed by electrode pads 31 described later.

Reference numerals 29, 29 denote conduction holes on the downstream resistor 20 side, and each of the conduction holes 29 is a terminal region 2 of the downstream resistor 20.
The portions corresponding to portions 5 and 25 are exposed to the outside, and these conduction holes 28 are closed by electrode pads 32 described later.

Reference numerals 30, 30, 31, 31, 32, and 32 denote electrode pads provided on the protective film 26 so as to close the conduction holes 27, 28, and 29.
2 is made of, for example, aluminum, etc.
7, 28 and 29 are electrically connected to the terminal regions 13, 19 and 25, respectively.

Reference numerals 33, 33, 34, 34, 35, 35 denote electrode pads 30, 31, 32 and terminal regions 13, 19, 25.
The stress relaxing layers 33, 34, and 35 are formed of a metal compound of platinum and aluminum by a manufacturing process described later, and the stress relaxing layers 33, 34, and 35 are formed in FIG. 6, the electrode pads 30, 31, 32 and the terminal regions 13, 19, 25
And are connected in a state where the adhesion is enhanced. Further, the stress relaxation layers 33, 34, 35 are formed by the resistors 8, 14,.
This is to relieve the film stress of the resistors 8, 14, 20 generated in the 20 heater regions 12 and the detection regions 18, 24.

Are bonding wires (2
The bonding wire 36 detects the resistors 8, 14, 20 by connecting the electrode pads 30, 31, 32 to a detection circuit (none shown) using an external connector terminal. Connected to circuit.

The flow rate detecting device 4 according to the present embodiment has the above-described configuration. Next, the operation of detecting the flow rate of the intake air will be described.

Here, on the substrate 5, the upstream resistor 1
4, since the heater resistor 8 and the downstream resistor 20 are arranged in parallel, as shown in FIGS. 1 and 2, when the intake air flows along the substrate 5 in the direction indicated by the arrow A. The detection region 18 of the upstream resistor 14 located on the upstream side of the substrate 5 is cooled by the air, and the detection region 24 of the downstream resistor 20 located on the downstream side receives heat from the heater region 12. As a result, the upstream resistor 14 and the downstream resistor 20
A difference is generated in the detection signal output from the circuit, and this difference is output to a detection circuit in the circuit casing 2, and the detection circuit can calculate the flow direction and the flow velocity of the intake air.

Next, a method for manufacturing the flow rate detecting device 4 according to the present embodiment will be described with reference to FIGS. FIGS. 7 to 10 show enlarged cross-sections of the main parts similar to those in FIG. 6, and therefore, the portion of the heater resistor 8 will be described as a representative, and other upstream-side resistors 14,
The description of the downstream resistor 20 is omitted.

First, in substantially the same manner as in the prior art, a thermal oxidation method, CVD
An insulating film forming step of forming an insulating film 6 such as a silicon oxide film or a silicon nitride film by a method such as a method;
A temperature-sensitive resistor forming step of forming a heater resistor 8, an upstream resistor 14, and a downstream resistor 20 by a CVD method, a sputtering method, or the like. A protective film forming step of forming a protective film 26 such as a silicon oxide film or a silicon nitride film on the surface of the substrate by means such as a CVD method. At this time, the insulating film 6 and the protective film 2
6, the resistors 8, 14, 20 sandwiched between the films 6, 26 are also joined in a state of increasing the adhesion.

Next, in the heat treatment step shown in FIG.
Is subjected to a heat treatment at about 800 to 1000 ° C. in an atmosphere of an inert gas (for example, argon), nitrogen gas, or the like, to set the heater resistor 8 to a predetermined resistance value and a predetermined temperature coefficient.

In the conductive hole forming step shown in FIG. 8, a conductive hole 27 for exposing a portion of the protective film 26 corresponding to the terminal region 13 of the resistor 8 is formed by etching.

Further, in the electrode pad forming step shown in FIG. 9, aluminum is evaporated by a sputtering method or the like, and the electrode pad 30 is formed so as to close the conduction hole 27 and cover the protection film 26 in this portion. At this time, the heater resistor 8 made of platinum and the electrode pad 30 made of aluminum come into contact with each other through the conduction hole 27.

Next, in the stress relaxation layer forming step shown in FIG. 10, the substrate 5 is heated at about 300 to 600 ° C. in an atmosphere of an inert gas (for example, argon), nitrogen gas, or the like, so that a heater resistor is formed. A portion where the electrode 8 and the electrode pad 30 are in contact is dissolved to generate a metal compound, and the metal compound becomes the stress relaxation layer 33.

As described above, since the stress relaxation layer 33 is formed by dissolving platinum as the material of the heater resistor 8 and aluminum as the material of the electrode pad 30, the stress relaxation layer 33 is formed. The electrode pad 30 and the heater resistor 8 can be connected through the conduction hole 27 in a state where the adhesion is enhanced.

The thermal expansion coefficients of silicon forming the substrate 5, platinum forming the heater resistor 8, and aluminum forming the electrode pad 30 are usually 23.1 × 10 ^{−6 for} aluminum and platinum for platinum. 10.2 × 10
^-6 , silicon is 2.4 × 10 ^-6 and aluminum>
The order is platinum> silicon. Thus, in the stress relaxation layer forming step, the metal compound (stress relaxation layer 33) formed while being heated to about 300 to 600 ° C. does not generate stress at this temperature. However, the substrate 5
When the temperature is lowered to room temperature, the stress relaxing layer 33 is formed as a metal compound containing platinum and aluminum, so that a film stress between platinum and aluminum is generated in the stress relaxing layer 33. Then, the stress relaxation layer 33 connects the electrode pad 30 and the terminal region 13 with a film stress between platinum and aluminum.

Thus, in the flow detecting device 4 according to the present embodiment, the electrode pads 3 connected through the conductive holes 27
0 and the terminal region 13 of the heater resistor 8, a stress relaxation layer 33 is formed between the electrode pad 31 connected through the conduction hole 28 and the terminal region 19 of the upstream resistor 14. The layer 34 is formed, and the stress relaxation layer 35 is formed between the electrode pad 32 connected via the conduction hole 29 and the terminal region 25 of the downstream resistor 20. Thereby, the electrode pads 30, 3 are formed by the stress relaxation layers 33, 34, 35.
1 and 32 can be connected to the terminal regions 13, 19 and 25 in a state where the adhesion is enhanced.

Thus, even if the resistors 8, 14, and 20 rise in the terminal regions 13, 19, and 25 from the insulating film 6 by releasing the film stress in the terminal regions 13, 19, and 25, the stress is relaxed. Electrode pads 30, joined to terminal regions 13, 19, 25 by layers 33, 34, 35,
31 and 32 cover the terminal regions 13, 19 and 25 with the insulating film 6;
The terminal regions 13, 19, and 25 can be fixed by preventing them from floating from the insulating film 6.

Further, the stress relaxation layers 33, 34, 35
As shown in the stress relaxation layer forming step described above, 300 to 60
Since it is formed as a metal compound of platinum and aluminum by heat treatment at about 0 ° C., it has a film stress between platinum and aluminum. Thereby, the terminal regions 13, 1
Even if the release of the film stress that causes the resistors 8, 14, and 20 to float up from the insulating film 6 occurs at 9, 25, the stress relaxation layers 33, 34, and 35 remain at the film between the platinum and aluminum. The release of the film stress generated in the resistors 8, 14, and 20 can be reduced by the stress.

Further, in this stress relaxation layer forming step, a heat treatment for heating the substrate 5 is performed, so that the heater resistor 8 is heated.
Where the electrode 14 and the electrode pad 30 are in contact with each other.
Where the electrode 20 and the electrode pad 31 contact each other, the downstream resistor 20
The stress relaxation layer 3
3, 34, 35 can be easily formed.

As described above, the stress relaxation layers 33, 34, 35
By connecting the resistors 8, 14, 20 joined via the conduction holes 27, 28, 29 to the electrode pads 30, 31, 32 with improved adhesion, electrical contact failure can be eliminated. it can. Further, the electrode pads 30, 31,
32 prevents the resistors 8, 14, and 20 from peeling off the insulating film 6. As a result, the reliability and life of the flow detection device 4 can be improved.

On the other hand, the stress relaxation layers 33, 34, 35 are formed in the terminal regions 13, 1 having a large area among the resistors 8, 14, 20.
Since they are formed at positions 9 and 25, even if the temperature coefficient of this portion slightly changes due to the heat treatment, they can be ignored compared to the resistance values of the heater region 12, the detection regions 18 and 24, and the resistors 8, 14, and The stress relaxation layers 33, 34, and 35 can be formed without affecting the temperature coefficient of 20.

Next, a second embodiment according to the present invention will be described with reference to FIGS. 11 to 15. In this embodiment, the stress relaxation layer is formed by sputtering with the metal material of the temperature-sensitive resistor. This is because a metal compound obtained by combining the metal material of the electrode pad and the metal material of the electrode pad is formed by vapor deposition in the deep part of the conduction hole. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, the description thereof will be omitted, and the heater resistor will be described as a representative.

Reference numeral 41 denotes a flow rate detecting device applied to the present embodiment.
Almost similarly to the above, the substrate 5, the insulating film 6 formed on the surface of the substrate 5, the heater resistor 8, the upstream resistor 14, the downstream resistor 20 provided on the insulating film 6, The protection film 26 is provided to cover the surfaces of the resistors 8, 14, 20 and the insulating film 6 (only the positive wiring region 9 of the heater resistor 8 is shown in the drawing).

Reference numeral 42 denotes a stress relieving layer used in the flow rate detecting device 41. The stress relieving layer 42 is formed on a terminal region 13 corresponding to a deep portion of the conduction hole 27 by sputtering a metal compound obtained by combining aluminum and platinum. It is formed in.

Reference numeral 43 denotes an electrode pad provided on the protective film 26 so as to close the conduction hole 27. The electrode pad 43 is formed of, for example, aluminum or the like, and is connected to the stress relaxation layer 42 and the terminal region 13 through the conduction hole 27. It is electrically connected.

A bonding wire 44 connects the electrode pad 43 to an external detection circuit (not shown).

In the flow rate detecting device 41 configured as described above, the operation of detecting the flow rate of the intake air can be detected in the same manner as in the above-described first embodiment.

Next, the method of manufacturing the flow rate detecting device 41 is substantially the same as that of the first embodiment described above, but differs in the process of manufacturing the stress relaxation layer 42.

First, in the heat treatment step shown in FIG. 12, the substrate 5 is subjected to a heat treatment at about 800 to 1000 ° C. in an atmosphere of an inert gas (eg, argon), nitrogen gas, or the like, so that the heater resistor 8 is heated to a predetermined temperature. And the temperature coefficient.

In the conductive hole forming step shown in FIG.
A conduction hole 27 exposing a portion of the protective film 26 corresponding to the terminal region 13 of the resistor 8 is formed by etching.

In the step of forming a stress relaxation layer shown in FIG. 14, a metal compound obtained by combining aluminum and platinum is vapor-deposited on the terminal region 13 located in the deep portion of the conduction hole 27 by a sputtering method or the like. A layer 42 is formed. At this time, the film stress of the stress relieving layer 42 is adjusted by controlling the film thickness and film quality by a sputtering device.

Further, in the electrode pad forming step shown in FIG. 15, an electrode pad 43 is formed of aluminum so as to close the conduction hole 27 by a sputtering method or the like so as to cover the protection film 26 in this portion. At this time, the electrode pad 43 is connected to the terminal region 13 by using the stress relaxation layer 42 in a state where the adhesion is enhanced.

As described above, when the stress relaxation layer 42 is formed, the film stress of the stress relaxation layer 42 is adjusted by controlling the sputtering apparatus, so that the insulating film of the heater resistor 8 generated in the terminal region 13 is formed. 6, the release of the film stress that tends to rise from the film 6 can be eased. This allows
Poor electrical contact between the heater resistor 8 and the electrode pad 43 is prevented, and the reliability and life of the flow rate detection device 41 can be improved.

In each of the embodiments, the positive wiring regions 9, 15, 21 are disposed upstream with respect to the flow of the intake air, and the negative wiring regions 11, 17, 23 are disposed downstream. However, the present invention is not limited to this.
1, 17 and 23 are arranged on the upstream side, and the positive-side wiring regions 9 and 1 are arranged.
It is good also as composition which arranges 5, 21 on the downstream side.

Further, in the embodiment, the case where the flow rate detecting device is used for measuring the intake air amount of an automobile engine or the like has been described as an example. However, the present invention is not limited to this, and the flow rate or flow rate of an arbitrary gas is detected. It may be applied when doing.

Further, in each embodiment, the case where the insulating film 6 and the protective film 26 are formed of silicon oxide and silicon nitride has been described. However, the present invention is not limited to this, and the insulating film and the protective film may be formed of silicon nitride and silicon oxide. May be used instead of a multilayer film formed alternately in multiple layers.

[0078]

As described above in detail, according to the first aspect of the present invention, the film stress of the temperature sensitive resistor is reduced between the electrode pad connected through the conduction hole and the terminal region of the temperature sensitive resistor. Since the stress-relief layer is formed, the temperature-sensitive resistor (terminal region) located in the conductive hole relaxes the release of the film stress that tends to rise from the insulating film by the stress-relaxation layer, and the terminal region becomes the insulating film. Can be fixed. This prevents poor electrical contact between the temperature-sensitive resistor and the electrode pad, and enhances the reliability of the flow rate detection device.

According to the second aspect of the present invention, the stress relaxation layer is made of a metal compound obtained by combining the metal material of the temperature-sensitive resistor and the metal material of the electrode pad. In the method, the film stress of the stress relaxation layer can be adjusted, and even if the release of the film stress occurs in the terminal region, the stress relaxation having the film stress between the metal material of the temperature-sensitive resistor and the metal material of the electrode pad can be performed. The difference in film stress can be reduced by the layer, and the terminal region can be fixed to the insulating film.

According to the third aspect of the present invention, the insulating film and the protective film are formed of any one of a silicon nitride film, a silicon oxide film, and a multilayer film composed of silicon nitride and silicon oxide, and the temperature-sensitive resistor is formed of platinum. Since the electrode pad is formed of aluminum and the stress relaxation layer is formed of a metal compound containing aluminum and platinum, for example, when the insulating film and the protective film are formed of the same silicon nitride, the insulating film and the protective film Can have substantially the same coefficient of thermal expansion, and the insulating film and the protective film can be joined in a state of increasing adhesion. In addition, the temperature-sensitive resistor was formed of platinum, the electrode pad was formed of aluminum, and the stress relaxation layer was formed with a metal compound containing aluminum and platinum so as to have a film stress between aluminum and platinum. Even when the release of the film stress occurs, the difference in the film stress can be reduced by the stress relaxation layer having the film stress between aluminum and platinum, and the terminal region can be fixed to the insulating film.

According to the fourth aspect of the present invention, the temperature-sensitive resistor is provided on the first temperature-sensitive resistor, the heater resistor, and the second
The first temperature-sensitive resistor is arranged in parallel on one side in the width direction and the second temperature-sensitive resistor is arranged in parallel on the other side in the width direction with the heater resistor interposed therebetween.

According to the fifth aspect of the present invention, the heater resistor includes a positive wiring region and a negative wiring region provided with a gap in the longitudinal direction of the substrate; A heater region provided at a portion connecting one end in the length direction, and a terminal region provided at the other end in the length direction of the positive wiring region and the negative wiring region, respectively. The first and second temperature-sensitive resistors include a positive wiring region and a negative wiring region provided with a gap in the length direction of the substrate;
A detection region provided at a portion connecting one end in the length direction of the positive wiring region and the negative wiring region; and a detection region provided at the other end in the length direction of the positive wiring region and the negative wiring region. Since the first temperature sensitive resistor and the second temperature sensitive resistor are arranged in parallel in the width direction with the heater resistor interposed therebetween, the terminal region is provided along the substrate. When the fluid flows from one side in the width direction, the first temperature-sensitive resistor is cooled, and the second temperature-sensitive resistor is cooled.
Is heated by the heat of the heater resistor.
Then, from the change in the resistance value of the first and second temperature sensitive resistors,
The flow direction and flow rate (flow velocity) of the fluid can be detected.

According to the sixth aspect of the present invention, by applying heat while the electrode pad is in contact with the terminal region through the conduction hole, the stress relaxation layer is formed by the metal compound generated at the interface between the electrode pad and the terminal region. Since the electrode pad is formed, the electrode pad can be connected to the terminal region by the stress relieving layer in a state of increasing adhesion. Moreover, although no stress is generated in the stress relieving layer at a high temperature, a film stress between the temperature-sensitive resistor and the electrode pad is generated in the stress relieving layer when the temperature returns to normal temperature. Thereby, the difference in film stress between the temperature-sensitive resistor and the electrode pad generated in the terminal region can be reduced, and the terminal region can be fixed to the insulating film.

According to the seventh aspect of the present invention, since the stress relaxation layer is formed by depositing a metal compound in the deep portion of the conduction hole, the film thickness and the film quality are controlled by, for example, a sputtering method, and the stress relaxation layer is formed. Adjust the film stress. Thereby, the difference in the film stress between the temperature-sensitive resistor and the electrode pad generated in the terminal region is reduced by the stress relaxation layer having the film stress,
The terminal region can be fixed to the insulating film.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state in which a flow rate detection device used in a first embodiment is disposed in a cylinder.

FIG. 2 is a perspective view showing a flow detection device according to the first embodiment.

FIG. 3 is a plan view showing a heater resistor, an upstream resistor, and a downstream resistor formed on a substrate.

FIG. 4 is an enlarged cross-sectional view showing the flow rate detection device viewed from the direction of arrows IV-IV in FIG. 2;

5 is an enlarged cross-sectional view of the flow rate detection device as viewed from the direction indicated by arrows VV in FIG. 2;

FIG. 6 is an enlarged sectional view of a main part of FIG.

FIG. 7 is a cross-sectional view showing a heat treatment step of heating a substrate.

FIG. 8 is a sectional view showing a conduction hole forming step of forming a conduction hole in a protective film after a heat treatment step.

FIG. 9 is a cross-sectional view showing an electrode pad forming step of forming an electrode pad in the conductive hole formed in the protective film in the conductive hole forming step.

FIG. 10 is a sectional view showing a stress relaxation layer forming step of forming a stress relaxation layer by heating the substrate in a state where the electrode pads are formed in the electrode pad forming step.

FIG. 11 is an enlarged cross-sectional view illustrating a main part of a flow rate detection device according to a second embodiment;

FIG. 12 is a cross-sectional view showing a heat treatment step of heating a substrate.

FIG. 13 is a cross-sectional view showing a conduction hole forming step of forming a conduction hole in a protective film after a heat treatment step.

FIG. 14 is a cross-sectional view showing a stress relaxation layer forming step of forming a stress relaxation layer by a sputtering method in the conduction hole formed in the protective film in the conduction hole forming step.

FIG. 15 is a cross-sectional view showing an electrode pad forming step of forming an electrode pad on the stress relaxing layer formed in the stress relaxing layer forming step.

[Explanation of symbols]

 4, 41 Flow rate detector 5 Substrate 6 Insulating film 8 Heater resistor 9, 15, 21 Positive wiring area 10, 16, 22 Gap 11, 17, 23 Negative wiring area 12 Heater area (detection area) 13, 19, 25 Terminal area 14 Upstream resistor (first temperature-sensitive resistor) 18, 24 Detection area 20 Downstream resistor (second temperature-sensitive resistor) 26 Protective film 27, 28, 29 Conducting hole 30, 31, 32,43 Electrode pad 33,34,35,42 Stress relaxation layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Orimo, Inventor 1370, Onna, Atsugi-shi, Kanagawa Prefecture (72) Tsuyoshi Matsumoto 1370 Onna, Atsugi-shi, Kanagawa, Japan Term (reference) 2F035 AA02 EA08

Claims (7)

[Claims] 1. A substrate, an insulating film formed on a surface of the substrate, a temperature-sensitive resistor provided on the insulating film, and a surface provided over the surface of the temperature-sensitive resistor and the insulating film. In the flow rate detection device comprising a protective film provided, the protective film is provided with a conduction hole for exposing a portion corresponding to a terminal region for connecting the temperature-sensitive resistor to the outside, and on the protective film, Providing an electrode pad connected to the terminal region of the temperature-sensitive resistor in a state where the conduction hole is closed, between the electrode pad and the terminal region of the temperature-sensitive resistor,
A flow rate detecting device comprising a stress relaxation layer for reducing a difference in film stress between a temperature-sensitive resistor and an electrode pad generated in the terminal region. 2. The flow rate detecting device according to claim 1, wherein the stress relaxation layer is made of a metal compound obtained by combining a metal material of the temperature-sensitive resistor and a metal material of the electrode pad. 3. The insulating film and the protective film are formed of any one of a silicon nitride film, a silicon oxide film, and a multilayer film composed of silicon nitride and silicon oxide, and the temperature-sensitive resistor is formed of platinum. 3. The flow rate detecting device according to claim 1, wherein the pad is formed of aluminum, and the stress relaxation layer is formed of a metal compound containing aluminum and platinum. 4. The temperature-sensitive resistor includes a first temperature-sensitive resistor, a heater resistor, and a second temperature-sensitive resistor provided on a substrate, and is located on one side in the width direction with the heater resistor interposed therebetween. 4. The flow detecting device according to claim 1, wherein the first temperature-sensitive resistor is arranged in parallel with the second temperature-sensitive resistor on the other side in the width direction. 5. The heater resistor includes a positive wiring region and a negative wiring region provided with a gap in a length direction of the substrate, and a lengthwise direction between the positive wiring region and the negative wiring region. A heater region provided at a portion connecting one end side, and a terminal region provided at the other end side in the length direction of the positive side wiring region and the negative side wiring region;
The second temperature sensitive resistor includes a positive wiring region and a negative wiring region provided with a gap in the length direction of the substrate, and one end in the length direction of the positive wiring region and the negative wiring region. 5. The flow rate according to claim 4, comprising a detection region provided at a portion connecting the first wiring region and a terminal region provided at the other end in the length direction of the positive wiring region and the negative wiring region. 6. Detection device. 6. An insulating film is formed on a surface of a substrate made of a silicon material, a temperature-sensitive resistor is formed on the insulating film, and a surface of the temperature-sensitive resistor and a surface of the insulating film are covered. A protective film is formed, a conductive hole is formed in the protective film to expose a portion corresponding to a terminal region for connecting a temperature-sensitive resistor to the outside, and an electrode is formed on the protective film in a state where the conductive hole is closed. A flow rate detecting device comprising a pad, a stress relaxation layer formed by a metal compound generated at a boundary surface between the electrode pad and the terminal region by applying heat while the electrode pad is in contact with the terminal region. Production method. 7. An insulating film is formed on a surface of a substrate made of a silicon material, a temperature-sensitive resistor is formed on the insulating film, and the surface of the temperature-sensitive resistor and the surface of the insulating film are covered. A protective film is formed, and a conductive hole is formed on the protective film to expose a portion corresponding to a terminal region for connecting the temperature-sensitive resistor to the outside, and a metal material of the temperature-sensitive resistor is formed in a deep portion of the conductive hole. An electrode pad for forming a stress relieving layer by depositing a metal compound obtained by combining a metal material with the metal material of the electrode pad, and connecting to a terminal region via the stress relieving layer on the protective film in a state where the conductive hole is closed. A method for manufacturing a flow rate detection device comprising: