JP2003021547A - Thin film sensor and flow sensor and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain etching of a thin film structure part which is caused by foreign matters in external environment, in a flow sensor having a thin film structure part. SOLUTION: The flow sensor is equipped with the thin film structure part 2 formed on a cavity part 6 of a substrate 1, a heater 3 and a temperature detector 5 which are formed in the thin film structure part 2, and a lead part 7 wherein one end is electrically connected with the heater 3 and the temperature detector 5 and the other end is led out as far as a part position except the thin film structure part 2 of the substrate 1. While heating and driving the heater 3, the flow sensor measures the flow rate of fluid on the basis of temperature change of the temperature detector 5 which is caused by flow of the fluid. The one end side of the lead part 7 has a form in which the lengthwise direction becomes the normal direction of constant temperature lines of temperature distribution generated in the thin film structure part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film sensor in which a resistive film including at least a heating element is formed in a thin film structure provided on a substrate, and a flow for detecting the flow rate of a fluid as such a thin film sensor. The present invention relates to a sensor and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a thin film type sensor of this type, for example, a semiconductor substrate is used, and a heater (heating element) and a temperature measuring element having a film structure are provided in one opening of a cavity formed in the substrate. As a result, various flow sensors have been proposed which are designed to measure the flow rate of fluid flowing through the heater and the temperature measuring element.

FIG. 8 is a perspective view showing an example of a conventional flow sensor, and FIG. 9 is a view showing a sectional structure taken along line AA in FIG. As shown in FIG. 8, a cavity portion 6 is provided from the back surface side of the substrate 1 to form a thin film structure portion 2 which is an electrically insulating film made of a diaphragm.

A meandering heater 3 as a heating element is formed in the vicinity of the center on the surface side of the substrate 1 in the thin film structure portion 2. On both sides of the heater 3, a fluid indicated by an outlined arrow in FIG. The temperature measuring element 5 is formed on the upstream side of the flow of the. A fluid thermometer 4 for measuring the temperature of the fluid is formed on the substrate 1 on the upstream side of the temperature measuring element 5.

Further, the surface of the substrate 1 is electrically connected to the heater 3, the fluid thermometer 4, and the temperature measuring body 5, and the lead portion 7 for electrically connecting these respective portions 3 to 5 and the outside.
Are formed. The lead portion 7, one end of which is connected to the heater 3 and the temperature sensing element 5, is formed such that the other end thereof is pulled out from the thin film structure portion 2 to a portion of the substrate 1 other than the thin film structure portion 2.

Further, as shown in FIG. 9, the thin film structure 2 is
Si, which is a film material used in general IC processes
It is configured by laminating insulating films 11 to 14 such as N (silicon nitride film) or SiO ₂ (silicon oxide film). The heater 3, the fluid thermometer 4, the temperature measuring element 5, and the lead portion 7 formed by patterning a resistance film such as Pt are interposed between the insulating films 11 to 14.

In such a flow sensor, the heater 3 is heated and driven so that the temperature is higher by a constant temperature than the fluid temperature obtained from the fluid thermometer 4. Then, as the fluid flows, in the forward flow indicated by the white arrow in FIG.
Since the temperature of the temperature sensing element 5 is deprived of heat, the temperature decreases, and the temperature rises due to heat being carried in the reverse flow which is the opposite direction of the white arrow. Therefore, due to the temperature difference between the temperature sensing element 5 and the fluid thermometer 4, The flow rate and the flow direction of are detected. It should be noted that the temperature is measured (detected) from the resistance value variation of the metal wiring forming the fluid thermometer 4 and the temperature measuring element 5.

[0008]

However, according to the study by the present inventors, in the conventional flow sensor, the SiN
When the sensor is driven in a high temperature and high humidity environment after the insulating films 11 to 14 such as SiO ₂ and SiO ₂ are exposed to foreign substances such as salt water, acid and alkali existing in the external environment, they are etched from the outermost surface. It was found that there was a problem that holes were formed in the thin film structure portion 2 and the thin film structure portion 2 was damaged as a result.

This is because salts, acids, etc. adhere to the thin film structure portion 2 and then the thin film structure portion 2 is heated by the heater 3 in a high humidity environment. This is because it reacts with acid or the like) and is etched.

Further, according to the study by the present inventors, in the above-mentioned conventional flow sensor, as shown in FIG. 10, in the vicinity of one end of the lead portion 7 located on the thin film structure portion 2 (in FIG. 10,
It was found that foreign matter is likely to adhere to the area surrounded by the broken line circle). This is considered to be due to the following reasons.

In order to reduce foreign substances adhering to the vicinity of the heater (heating element) 3, the driving temperature of the heater 3 is set to be 2 times higher than the fluid temperature.
Generally, the temperature is about 00 ° C. higher. From this, the temperature of the resistive film in the thin film structure 2, that is, the portion (detection portion) where the heater 3 and the temperature sensing element 5 are located is higher than the temperature around the detection portion.

That is, as shown in FIG. 11, the temperature distribution generated in the thin film structure portion 2 when the heater 3 is driven has an isotherm L close to a concentric circle extending from the central portion to the peripheral portion of the heater 3, that is, the thin film structure portion 2. Will have.

As a result, in the central portion of the thin film structure 2 having a high temperature, foreign matter is blown off and is not easily etched.
On the other hand, as shown by the arrow in FIG. 11, the foreign matter is scattered along the normal direction of the isotherm L from the high temperature central portion to the low temperature peripheral portion, but the foreign matter is diffused in the low temperature peripheral portion. Since it is hard to fly, the foreign matter is likely to accumulate in the step around the lead portion 7 located in the peripheral portion of the thin film structure portion 2.

Further, such a problem is not limited to the flow sensor described above, but includes a thin film structure portion provided on the cavity of the substrate such as a gas sensor and a humidity sensor, and at least a heating element formed in the thin film structure portion. A thin-film sensor including a resistance film including the same and a lead portion that is electrically connected at one end to the resistance film and is drawn at the other end side to a portion of the substrate other than the thin-film structure portion is commonly used. It is thought to occur.

In view of the above problems, it is an object of the present invention to suppress etching of a thin film structure portion due to foreign matter in the external environment in a thin film sensor or a flow sensor.

[0016]

In order to achieve the above object, a substrate (1) having a cavity (6), a thin film structure portion (2) provided on the cavity of the substrate, and this thin film structure. A resistive film (3,
5) and a lead portion (7) which is formed by electrically connecting one end to the resistance film and pulling out the other end side to a portion of the substrate other than the thin film structure portion to heat and drive the heating element. On the other hand, in a thin-film sensor that measures the flow rate of the fluid based on the temperature change of the temperature sensing element due to the flow of the fluid, the longitudinal direction of the one end of the lead is equal to the temperature distribution generated in the thin-film structure. It is characterized in that it is shaped so as to be in the normal direction of the line.

According to this, the lead portion can have a shape extending in the normal direction of the above-mentioned isotherm, that is, in the direction in which the foreign matter moves. Therefore, like the effect of a streamlined object, even if a foreign matter hits the step of the lead portion, the foreign matter is likely to move to the outside of the thin film structure without accumulating.

That is, in the prior art, for example, as shown in FIG.
As shown in FIG. 11, since the lead portion does not have a shape extending in the normal direction of the isotherm, there are many portions where foreign matter collides with the stepped portion of the lead portion, and as a result, foreign matter tends to accumulate. On the other hand, in the present invention, the above-described action makes it difficult for foreign matter to accumulate near the lead portion,
It is possible to provide a thin film sensor capable of suppressing etching of the thin film structure portion due to foreign matter in the external environment.

Further, in the invention described in claim 2, the width of one end side of the lead portion (7) is the same as the width of the resistance film (3, 5) connected to the one end side. And
Thereby, in the step of the lead part on the thin film structure part,
The area where foreign matter collides can be further reduced, which is preferable.

Further, the invention according to claim 3 is characterized in that the lead portion (7) has a shape in which the width gradually increases from one end side to the other end side. As a result, the same effect as that of the invention of claim 2 is obtained.

In the invention according to claim 7, the substrate (1) having the cavity (6), the thin film structure (2) provided on the cavity of the substrate, and the thin film structure are provided in the thin film structure. The heating element (3) and the temperature measuring element (5) thus formed are formed such that one end is electrically connected to the heating element and the temperature measuring element and the other end side is pulled out to a portion of the substrate other than the thin film structure portion. And a lead portion (7) for heating the heating element to measure the flow rate of the fluid based on the temperature change of the temperature sensing element due to the flow of the fluid, at least on the heating element, It is characterized by being covered with a protective film (10) having etching resistance.

The portion of the thin film structure where the heating element is located is likely to reach the highest temperature, and when foreign matter adheres, the etching reaction is promoted by the high temperature and the etching easily proceeds.

In this respect, according to the present invention, since the etching resistant protective film is provided on the heating element, it is possible to prevent the etching of the thin film structure portion below the protective film. Therefore, according to the present invention, it is possible to provide a flow sensor capable of suppressing the etching of the thin film structure portion due to the foreign matter in the external environment.

Further, in the invention described in claim 4, in the thin film sensor according to any one of claims 1 to 3, at least the heating element (3) is covered with an etching resistant protective film (10). It is characterized by being covered by.
According to this, in addition to the effects of the inventions of claims 1 to 3, it is possible to provide a thin-film sensor capable of exhibiting the same effects as the invention of claim 7.

Further, as in the invention described in claim 6, in the thin film type sensor described in claims 1 to 5, the resistance film has the temperature measuring element (5) in addition to the heating element (5). Is something
It can be used as a flow sensor adapted to measure the flow rate of the fluid based on the temperature change of the temperature measuring element due to the flow of the fluid while heating and driving the heating element.

Further, as in the invention described in claims 5 and 8, as the protective film (10), an alumina or fluorine-based film can be adopted.

Further, in the invention according to claim 9, in the flow sensor according to claim 7 or 8, the protective film (1
0) is characterized in that the temperature measuring element (5) and the lead portion (7) are also covered.

In the flow sensor, the temperature measuring element and the lead portion are the portions through which the current flows, and like the arrangement area of the heating element,
This is a portion where the temperature becomes high and the etching reaction is easily promoted. In the present invention, by coating these with a protective film, it is possible to suppress etching of the thin film structure portion due to foreign matter in the external environment.

According to a tenth aspect of the invention, in the flow sensor according to the seventh to ninth aspects, the other end side of the lead portion (7) has a pad portion (for electrically connecting to the outside). 8) is provided, and the protective film (10) also covers this pad portion.

As the pad material, a dissimilar metal such as A
In the case of using a u / Cu pad or the like, or in a connection structure of an Au pad and an Al wire or the like, there is a possibility that the pad may be eluted and etched and damaged due to a local battery effect due to water exposure or the like. In this respect, according to the present invention, such a problem can be avoided by covering the pad portion with the protective film.

According to the invention of claim 11, in the flow sensor of claims 7 to 10, the protective film (1
0) is not provided in the peripheral portion of the thin film structure portion (2).

If a protective film is provided around the thin film structure,
The peripheral portion becomes thicker accordingly. Then, heat easily escapes from the thin film structure portion to the thick portion of the substrate, resulting in a problem such as an increase in power consumption of the heating element. In that respect, according to the present invention, such a problem can be avoided.

Further, in the invention described in claim 12, the thin film structure portion (2) is formed on the hollow portion of the substrate having the hollow portion (6), and the heating element (3) and the temperature measuring device are formed in the thin film structure portion. The body (5) is provided, and one end is electrically connected to the heat generating body and the temperature measuring body, and the other end side is formed with the lead portion (7) extended to a portion of the substrate other than the thin film structure portion. The method of manufacturing a flow sensor includes a step of forming a protective film (10) covering at least the heating element, and in this step, an alumina film is formed as an atomic layer growth method (ALE method) as the protective film. Characterize.

Further, in the invention according to the thirteenth aspect, in the step of forming the protective film (10) covering at least the heating element, a fluorine-based film is formed as a protective film by a plasma polymerization method. And

According to the manufacturing methods of the twelfth and thirteenth aspects, the flow sensor according to the seventh to eleventh aspects can be appropriately manufactured. Particularly, in the case of a fluorine-based film (plasma polymer film) formed by plasma polymerization, since it has water repellency, it becomes difficult for foreign matter to adhere.

The reference numerals in parentheses for each means described above are examples showing the correspondence with specific means described in the embodiments described later.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment)
In the flow sensor having the configuration shown in FIGS. 8 and 9, a configuration in which one end side of the lead portion 7 electrically connected to the heater (heating element) 3 and the temperature measuring element 5 is modified is shown in FIG. This is a difference from the conventional example. Therefore, the difference will be mainly described below.

FIG. 1 is a top view showing a main part of a flow sensor according to the first embodiment of the present invention. One end side of the lead portion 7 is integrally connected to the meandering heater 3 and the temperature sensing element 5, and the other end side of the lead portion 7 is drawn out on the substrate 1 so as to extend to the outside of the thin film structure portion 2. Has been.

Here, one end side of the lead portion 7 is shaped such that its longitudinal direction is the normal direction of the isotherm of the temperature distribution generated in the thin film structure portion 2 when the heater 3 is driven. The positional relationship between the isotherm L and the lead portion 7 in this example is shown in FIG. Similar to FIG. 11, the isothermal line L is also substantially concentric in the present example from the high temperature central portion toward the low temperature peripheral portion.

According to the present embodiment having such a lead portion shape, the lead portion 7 can be made to have a shape extending along the normal direction of the above-mentioned isotherm L, that is, the direction in which foreign matter moves. Therefore, like the effect of a streamlined object, even if a foreign matter hits the step of the lead portion 7, the foreign matter does not collect and easily moves to the outside of the thin film structure 2.

As a result, in the present embodiment, it is possible to prevent foreign matter from accumulating near the one end side of the lead portion 7, so that it is possible to suppress etching of the thin film structure portion 2 due to foreign matter in the external environment.

Next, a method of manufacturing the flow sensor according to this embodiment will be described with reference to FIG. 9 described above. A single crystal silicon substrate 1 is used as a semiconductor substrate, a silicon nitride film 11 is formed on one surface (front surface) side thereof by an LPCVD method or the like, and a silicon oxide film 12 is formed thereon by a CVD method or the like (lower insulating film 11). , 12 forming step).

By laminating the silicon oxide film 12 on the silicon nitride film 11 in this manner, the adhesion with the wiring material formed on the silicon oxide film 11 is improved,
Further, when the thin film structure portion 2 is formed, since the water resistant silicon nitride film 11 is arranged on the outer side, the moisture resistance of the thin film structure portion 2 can be improved.

Next, a Pt film as a resistor material is formed at 200 ° C.
Is deposited on the silicon oxide film 12 by a vacuum vapor deposition machine, and the Pt film is patterned into the wiring shape of the heater 3, the fluid thermometer 4, the temperature measuring element 5, and the lead portion 7 by the etching (wiring portion 3 to Forming steps 5 and 7). here,
As the resistor material, polysilicon, NiCr, Ta
It may be N, SiC, W or the like.

Next, the heater 3, the fluid thermometer 4, the temperature measuring element 5
The silicon oxide film 1 for insulation between the lead portion 7 and the lead portion 7.
3 is deposited, and a silicon nitride film 14 which is a surface protection film is formed thereon (step of forming upper insulating films 13 and 14). Thereafter, an opening is formed in the silicon nitride film 14 to form an electrode pad (pad portion) 8 made of aluminum or the like on the other end side of the lead portion 7, and the electrode pad 8 is formed in the opening portion.
(See FIG. 8) is formed (step of forming the electrode pad 8).

Next, a mask material (for example, a silicon oxide film or a silicon nitride film, not shown) is formed on the back surface of the silicon substrate 1 and is etched to form an opening. Then, the back surface side of the silicon substrate 1 is anisotropically etched until the silicon nitride film 11 is exposed to form the cavity portion 6 (step of forming the cavity portion 6).

The end point detection at this time can be easily stopped by using, for example, TMAH (4-methylammonium hydroxide) as the etching solution, because the etching rate of the silicon nitride film 11 is very low with respect to that of silicon.

After that, wire bonding or the like is performed on the electrode pad 8, and the sensor and the outside (control circuit or the like) are electrically connected to each other via the wire or the like formed thereby (pad connecting step). In this way, the flow sensor according to this embodiment can be manufactured.

The shape of the lead portion in the present embodiment may be the shape shown in the following FIGS. 3 and 4 other than the example shown in FIG. 1 (first example). In the second example shown in FIG. 3, the width of the lead portion 7 on one end side is the same as the width of the corresponding heater (heating element) 3 and temperature measuring element 5. Also, FIG.
In the third example shown in, the lead portion 7 has a shape in which the width gradually increases from one end side to the other end side.

By adopting the shapes shown in FIGS. 3 and 4, it is possible to further reduce the area where foreign matter collides with the step of the lead portion 7 on the thin film structure 2.
preferable.

(Second Embodiment) The present embodiment differs from the flow sensor shown in FIGS. 8 and 9 in that at least the heater (heating element) 3 is covered with a protective film having etching resistance. To do.

FIG. 5 is a top view of the flow sensor according to this embodiment, and FIG. 6 is a schematic cross-sectional view of the thin film structure portion 2 and its vicinity in this flow sensor. In the example shown in FIG. 5, A that is wire-bonded to the electrode pad 8
The entire area of the substrate 1 including the wires 9 such as u and Al is covered with a protective film 10 (shown by hatching in FIG. 5).

As shown in FIG. 6, the protective film 10 is formed on the silicon nitride film 14 which is the outermost surface of the thin film structure portion 2, and covers and protects the lower layer as the outermost surface layer of the sensor. ing. This protective film 10 is not etched by foreign substances such as salt water, acid or alkali existing in the external environment, and specifically, an alumina (Al ₂ O ₃ ) film or a fluorine-based film may be adopted. it can.

In the process of forming the protective film 10, the lower insulating films 11 and 12 are formed and the wiring portions 3 to 3 are formed as in the first embodiment.
After the steps of forming 5 and 7, forming the upper insulating films 13 and 14, forming the electrode pad 8, forming the cavity portion 6 and pad connection are performed.

When an alumina film is formed as the protective film 10, an atomic layer growth method (ALE method), a sputtering method, and a CVD method are used.
It is formed by the method. The ALE method is preferable because it is easy to form a film on a three-dimensional structure such as the electrode pad 8 and the wire 9 and can be made thin.

On the other hand, when a fluorine-based coating is formed as the protective film 10, it is formed by a plasma polymerization method or the like. Specifically, it is formed by a plasma polymerization apparatus using CF ₄ / C ₄ F ₈ gas. The fluorine-based coating film thus formed is a plasma polymer film and has water repellency, so that foreign matter is less likely to adhere thereto. Note that in the case of such a fluorine-based film, the film will deteriorate unless the maximum temperature of use of the sensor is set to 300 ° C. or less.

As described above, in the sensor shown in FIG. 5, since the entire surface of the substrate 1 including the heater 3 is provided with the protective film 10 having etching resistance, the protective film 10 is covered with foreign matter. However, it is possible to prevent the lower part of the protective film 10 from being etched.

In particular, the portion of the thin film structure portion 2 where the heater 3 is located is the highest temperature, and when foreign matter adheres, the high temperature promotes the etching reaction due to the foreign matter and facilitates the progress of etching. Further, the temperature measuring element 5, the lead portion 7, and the fluid thermometer 4 are also portions through which an electric current flows, and like the arrangement area of the heater 3,
This is a portion where the etching reaction by foreign matter is easily promoted due to the high temperature.

On the other hand, according to the sensor shown in FIG. 5, since the etching resistant protective film is provided on the high temperature portion where the etching reaction is easily promoted, the entire flow sensor including the thin film structure portion 2 is externally connected. Etching due to foreign substances in the environment can be suppressed.

Further, in the sensor shown in FIG. 5, the lead portion 7
The protective film 10 also covers the electrode pad (pad portion) 8 provided on the other end side for electrically connecting to the outside. As a material for the pad portion, a dissimilar metal such as Au / Cu
When using a pad or the like, Au pad 8 and Al wire 9
In the connection structure with the like, the pad portion 8 may be eluted and etched and damaged due to a local battery effect due to water exposure or the like.

In this respect, according to this example, by covering the electrode pad 8 with the protective film 10, it is possible to prevent the electrode pad 8 from being damaged by water.

As described above, the portion where the heater 3 is located in the thin film structure portion 2 is the highest temperature in the sensor and is the portion in which etching by the foreign matter is most likely to proceed. Therefore, in the present embodiment, It is sufficient that at least the heater 3 is covered with the protective film 10.

FIG. 7 shows a modification of the second embodiment in which the protective film 10 is partially provided instead of the entire sensor. In FIG. 7, the protective film 10 is not provided in the vicinity of the end portion of the thin film structure portion 2 and in the vicinity of the electrode pad 8 and the wire 9 as compared with the one shown in FIG. That is, in the thin film structure portion 2, the protective film 10 is provided only in the high temperature portion where the heater 3 and the temperature sensing element 5 raise the temperature.

As shown in FIG. 7, if the protective film 10 is provided on at least the heater (heating element) 3 in the thin film structure portion 2 and is not provided in the peripheral portion of the thin film structure portion 2,
Since the film thickness of the peripheral portion of the thin film structure portion 2 can be kept thin, heat escape from the thin film structure portion 2 to the thick portion of the substrate 1 can be suppressed. As a result, it is possible to avoid a problem such as an increase in power consumption of the heater 3.

Further, as shown in FIG. 6, the protective film 10 does not have to be provided on the outermost surface of the sensor as long as it covers at least the wiring portions 3 to 5, 7. For example, in FIG. 6, the protective film 10 is provided between the silicon oxide film 13 as the upper insulating film and the silicon nitride film 14 as the upper insulating film so as to cover the heater 3 and the temperature sensing element 5.
May be interposed.

In this case, the protective film forming step may be performed between the forming steps of the upper insulating films 13 and 14. In this case, at least etching of the lower insulating films 11 and 12 due to foreign matter is suppressed, so that the thin film structure 2 is not cut and damaged.

(Other Embodiments) The first embodiment and the second embodiment may be combined. In this case, the longitudinal direction on one end side of the lead portion 7 is along the normal direction of the isotherm of the temperature distribution generated in the thin film structure portion 2, and at least the heater 3 is protected against etching. Since the structure is covered with the film 10, the effect of the second embodiment is added to the effect of the first embodiment described above.

Although the present invention has been described above with respect to the flow sensor, the present invention is also applicable to a heating type thin film sensor, for example, a gas sensor or a humidity sensor having a resistive film including a heater in a thin film structure. is there.

In summary, according to the present invention, the thin film structure portion provided on the cavity of the substrate, the resistance film including at least the heating element formed in the thin film structure portion, one end of which is electrically connected to the resistance film, etc. The present invention is applicable to a thin-film sensor including an end portion and a lead portion formed by being drawn out to a portion of the substrate other than the thin-film structure portion.

[Brief description of drawings]

FIG. 1 is a top view showing a main part of a flow sensor according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship between an isotherm and a lead portion in the thin film structure portion shown in FIG.

FIG. 3 is a diagram showing a second example of the first embodiment.

FIG. 4 is a diagram showing a third example of the first embodiment.

FIG. 5 is a top view of a flow sensor according to a second embodiment of the present invention.

6 is a schematic cross-sectional view of a thin film structure portion and its vicinity in the flow sensor shown in FIG.

FIG. 7 is a top view of a flow sensor as a modified example of the second embodiment.

FIG. 8 is a perspective view showing an example of a conventional flow sensor.

9 is a diagram showing a cross-sectional configuration along the line AA in FIG.

FIG. 10 is a top view showing the vicinity of a thin film structure portion of a conventional flow sensor.

FIG. 11 is an explanatory diagram showing a positional relationship between an isotherm and a lead portion in a thin film structure portion of a conventional flow sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Silicon substrate (substrate), 2 ... Thin film structure part, 3 ... Heater (heating element), 5 ... Temperature measuring body, 6 ... Cavity part, 7 ... Lead part, 10 ... Protective film.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01N 27/12 G01F 1/68 104A 104C F term (reference) 2F035 EA08 2G046 AA01 AA09 BA01 BB02 BC07 BF05 DB05 DC14 EA02 EA07 EA09 EA11 EA12 FB02 FB06 FE03 FE10 FE25 FE31 FE38 FE41 FE46

Claims (13)

[Claims] 1. A substrate (1) having a cavity (6), and a thin film structure (2) provided on the cavity of the substrate.
A resistance film (3, 5) including at least a heating element formed in the thin film structure portion, one end electrically connected to the resistance film, and the other end side of the substrate other than the thin film structure portion In a thin-film sensor including a lead portion (7) formed by being drawn up to the end, the longitudinal direction of one end side of the lead portion is a normal direction of an isotherm of a temperature distribution generated in the thin-film structure portion. A thin-film sensor characterized by having a shape such that 2. The resistance film (3, 5) having a width on the one end side of the lead portion (7) connected to the one end side.
2. The thin film sensor according to claim 1, wherein the thin film sensor has the same width. 3. The thin-film sensor according to claim 1, wherein the lead portion (7) has a shape in which the width gradually increases from the one end side to the other end side. . 4. The heating element (3) is covered with a protective film (10) having etching resistance at least on the heating element (3).
Thin film type sensor described in. 5. The thin film sensor according to claim 4, wherein the protective film (10) is an alumina or fluorine-based film. 6. The resistance film has a temperature measuring element (5) in addition to the heating element (5), and the temperature change of the temperature measuring element due to the flow of fluid while heating the heating element. The thin film sensor according to any one of claims 1 to 5, wherein the thin film sensor is used as a flow sensor configured to measure the flow rate of the fluid based on the above. 7. A substrate (1) having a cavity (6) and a thin film structure (2) provided on the cavity of the substrate.
A heating element (3) and a temperature measuring element (5) formed in the thin film structure, one end electrically connected to the heating element and the temperature measuring element, and the other end side of the thin film of the substrate. And a lead portion (7) formed by being drawn to a portion other than the structure portion, and the flow rate of the fluid is measured based on a temperature change of the temperature sensing element due to the flow of the fluid while heating and driving the heating element. In the above flow sensor, at least the heating element is covered with a protective film (10) having etching resistance. 8. The flow sensor according to claim 7, wherein the protective film (10) is an alumina or fluorine-based film. 9. The flow sensor according to claim 7, wherein the protective film (10) also covers the temperature measuring element (3) and the lead portion (7). 10. The other end of the lead part (7) is provided with a pad part (8) for electrically connecting to the outside, and the protective film (10) also covers the pad part. The flow sensor according to any one of claims 7 to 9, characterized in that: 11. The flow sensor according to claim 7, wherein the protective film (10) is not provided in the peripheral portion of the thin film structure portion (2). 12. A thin film structure (2) is formed on the cavity of a substrate having a cavity (6), and a heating element (3) and a temperature measuring element (5) are provided in the thin film structure. Manufacture of a flow sensor in which one end is electrically connected to the heating element and the temperature measuring element, and the other end side forms a lead portion (7) drawn to a portion of the substrate other than the thin film structure portion. The method includes a step of forming a protective film (10) covering at least the heating element, and in this step, an alumina film is formed as the protective film by an atomic layer growth method (ALE method). Flow sensor manufacturing method. 13. A thin film structure (2) is formed on the cavity of a substrate having a cavity (6), and a heating element (3) and a temperature measuring element (5) are provided in the thin film structure. Manufacture of a flow sensor in which one end is electrically connected to the heating element and the temperature measuring element, and the other end side forms a lead portion (7) drawn to a portion of the substrate other than the thin film structure portion. The method comprises a step of forming a protective film (10) covering at least the heating element, and in this step, a fluorine-based film is formed as the protective film by a plasma polymerization method. Production method.