JP2000283813A - Heat sensitive flow sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measuring sensitivity by providing an air gap opened at a semiconductor substrate side oppositely to a heater on an insulating layer on a surface of the substrate and temperature sensors disposed at upstream side, downstream side of the heater. SOLUTION: A thin film insulating layer 3 is formed on a surface of a semiconductor substrate 2, and a heater 11, an upstream side temperature measuring resistor 12 and a downstream side temperature measuring resistor 13 are formed on the layer 3. Lower portions of the heater 11, the resistors 12, 13 are removed by etching from their surface sides to form air gaps 4a, 4b, 4c. Thus, crosslinked bridges 5a, 5b, 5c are formed at the lower portions of the heater 11 and the resistors 12, 13 on the substrate 1. Thus, the substrate 11 is retained between the heater 11 and the resistor 12 and between the heater 11 and the resistor 13 to suppress transfers of the heat of the heater to the resistors 12, 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive flow sensor for measuring a flow rate and a flow rate of a fluid such as a gas or a liquid, which is suitable for a gas meter or the like. The present invention relates to a heat-sensitive flow sensor having increased sensitivity by suppressing conduction to a part.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive flow sensor using a heater has been proposed to measure the flow rate and flow rate of a fluid such as a gas or a liquid. This flow sensor has a configuration in which a heater portion and two temperature sensor portions are formed on the surface of a bridge portion having a bridge structure formed on a semiconductor substrate, and the two temperature sensor portions are arranged on both sides of the heater portion. .

This flow sensor utilizes the fact that the temperature distribution of heat generated by passing an electric current through the heater changes according to the flow rate and flow velocity of the fluid, and the amount of change is provided on both sides of the heater. It is detected by a temperature sensor unit.

FIG. 7 is a plan view (a) showing an example of such a conventional heat-sensitive flow sensor and a schematic cross-sectional view (b) thereof taken along line EE.

In FIG. 1, a thermal flow sensor 1 is
The insulating layer 3 is formed as a thin film on the surface of the semiconductor substrate 2, and the central region of the semiconductor substrate 2 is removed by etching from the surface side to form the void portion 4.
The upper insulating layer 3 has a configuration in which the bridge portion 5 is formed in a cross-linked manner.

A heater 11 is formed on the surface of the bridge 5 by forming a heating element in a concave shape, and a fluid flow direction (left-right direction in the drawing) F is formed adjacent to the heater 11.
An upstream temperature measuring resistor 12 is formed on the upstream side, and a downstream temperature measuring resistor 13 is formed on the downstream side. Further, wire pads 11 formed on the semiconductor substrate 2 outside the bridge portion 5 are provided at both ends of the heating element constituting the heater portion 11.
a and 11b are connected.

[0007] The upstream resistance temperature detector 12 and the downstream resistance temperature detector 13 are formed, for example, by a platinum thin film resistor in a fluid flow direction F.
Are formed in a zigzag shape, and both ends thereof are formed on the semiconductor substrate 2 outside the bridge portion 5 by wire pads 12a and 12b and wire pads 13a and 13b, respectively.
It is connected to the.

In this configuration, the thermal flow sensor 1
Are arranged in a direction in which the longitudinal direction of the heater section 11 is orthogonal to the flow direction F of the fluid, and the wire pad 11 of the heater section 11
When a current flows between a and 11b, the heater unit 11 generates heat.

When there is no fluid flow, the temperature distribution of the heat generated from the heater section 11 is symmetrical on both sides, so that
Two resistance temperature detectors 12, 1 provided on both sides of the heater section 11.
3 have the same resistance value.

When the fluid flows, the upstream temperature measuring resistor 12
Is cooled by the flow of the fluid, and the downstream resistance temperature detector 13
Is heated by the heat of the heater unit 11. This causes a difference between the resistance value of the upstream temperature measuring resistor 12 and the resistance value of the downstream temperature measuring resistor 13. The difference between the resistance values is represented by wire pad 1
It is recognized as a difference in voltage value between 2a, 12b and wire pads 13a, 13b. This difference increases as the flow velocity of the fluid increases, so that the flow velocity of the fluid can be measured.

[0011]

By the way, in the thermal type flow sensor, the sensitivity is improved so that the resistance temperature detectors 12 and 13 are affected by heat only from the fluid and are not affected by other components. However, in the structure of the conventional thermal flow sensor described above, since the heat is conducted from the heater section 11 to the temperature measuring resistors 12 and 13 through the insulating layer 3 forming the bridge section 5, the sensitivity may be reduced. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and suppresses the conduction of heat from a heater section to a temperature sensor section through an insulating layer, thereby providing a highly sensitive thermosensitive type. The purpose is to obtain a flow sensor.

[0013]

According to a first aspect of the present invention, there is provided a thermal flow sensor, comprising: an insulating layer formed in a thin film on a surface of a semiconductor substrate; a heater disposed on the surface of the insulating layer; A first and a second temperature sensor disposed on the surface of the insulating layer on the upstream and downstream sides of the fluid with the heater as a center, and a semiconductor facing the heater and the first and the second temperature sensor And first to third voids formed in the semiconductor substrate so as to open to the front side of the substrate.

According to the present invention, the first to third voids are provided on the front surface side of the semiconductor substrate, and the gap between the heater and the first temperature sensor and between the heater and the second temperature sensor are provided. Since the semiconductor substrate is left in between, the heat generated in the heater portion and transmitted through the insulating layer is absorbed by the semiconductor substrate and has an effect of suppressing conduction to the first and second temperature sensor portions. .

According to a second aspect of the present invention, there is provided a heat-sensitive type flow sensor, comprising: an insulating layer formed in a thin film on a surface of a semiconductor substrate; a heater disposed on the surface of the insulating layer; A first and a second temperature sensor disposed on the surface of the insulating layer on the upstream and downstream sides of the fluid, and a semiconductor opposed to a region from the first temperature sensor to the second temperature sensor; A void portion formed in the semiconductor substrate so as to open to the front surface side of the substrate;
A first heat absorber disposed in the gap portion facing the region between the temperature sensor portions, and a second heat absorber disposed in the gap portion facing the region between the heater portion and the second temperature sensor portion. And a heat absorber.

According to the present invention, the lower portion of the region between the heater portion and the first temperature sensor portion and the lower portion of the region between the heater portion and the second temperature sensor portion are provided in the gap provided on the front surface side of the semiconductor substrate. Since heat absorbers having high thermal conductivity are installed, heat generated in the heater portion and transmitted through the insulating layer is absorbed by the heat absorber, and the first and second heat absorbers are absorbed.
Has the effect of suppressing conduction to the temperature sensor section.

According to a third aspect of the present invention, there is provided a heat-sensitive type flow sensor, comprising: an insulating layer formed in a thin film on a surface of a semiconductor substrate; a heater disposed on the surface of the insulating layer; A first and a second temperature sensor disposed on the surface of the insulating layer on the upstream and downstream sides of the fluid, and a semiconductor opposed to a region from the first temperature sensor to the second temperature sensor; A void portion formed in the semiconductor substrate so as to open to the front surface side of the substrate;
A plurality of columnar first heat absorbers installed in the gap portion facing the region between the temperature sensor portions, and a heater portion and a second portion.
And a plurality of columnar second heat absorbers installed in the gap portion facing the region between the temperature sensor portions.

According to the present invention, the lower portion of the region between the heater portion and the first temperature sensor portion and the lower portion of the region between the heater portion and the second temperature sensor portion are formed in the gap provided on the surface of the semiconductor substrate. In addition, since a plurality of columnar heat absorbers each having a high heat conductivity are installed, heat generated in the heater portion and transmitted through the insulating layer is absorbed by the heat absorber, and the first heat absorber is absorbed by the first heat absorber.
And an effect of suppressing conduction to the second temperature sensor unit.

According to a fourth aspect of the present invention, there is provided a heat-sensitive type flow sensor, comprising: an insulating layer formed in a thin film on a surface of a semiconductor substrate; a heater disposed on the surface of the insulating layer; A first and a second temperature sensor disposed on the surface of the insulating layer on the upstream and downstream sides of the fluid, and a semiconductor opposed to a region from the first temperature sensor to the second temperature sensor; A gap formed in the semiconductor substrate so as to open on the front surface side of the substrate, a first heat absorbing layer provided between the heater and the first temperature sensor on the surface of the insulating layer, A second heat absorbing layer provided between the heater part on the front surface and the second temperature sensor part.

According to the present invention, heat generated in the heater portion and transmitted through the insulating layer is transferred to the heater portion by the first and second heaters.
Is absorbed by the first and second heat absorbing layers disposed in the insulating layer between the first and second temperature sensor sections, and has an effect of suppressing conduction to the first and second temperature sensor sections.

According to a fifth aspect of the present invention, there is provided a thermo-sensitive flow sensor according to the fourth aspect of the present invention.
The heat absorbing layer is provided so as to extend over the semiconductor substrate.

According to the present invention, since the semiconductor substrate has a high thermal conductivity, heat generated in the heater portion and transmitted through the insulating layer is transmitted to the semiconductor substrate through the first and second heat absorbing layers, and the first and second heat absorbing layers are transferred. It has the effect of suppressing conduction to the second temperature sensor.

According to a sixth aspect of the present invention, in the thermal flow sensor according to the fourth or fifth aspect, the first and second heat absorbing layers are provided with an isothermal curve of a temperature distribution of heat from the heater. On the contrary, it is installed in a bow shape that warps inward.

According to the present invention, the shape of the first and second heat absorbers is formed in the shape of a bow that is curved inward, opposite to the isothermal curve of the temperature distribution of heat from the heater, so that it is insulated from the heater. Heat transmitted through the layer is uniformly absorbed in accordance with the temperature distribution, and has an effect of suppressing conduction to the first and second temperature sensor units.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. In the following description, the same components as those shown in FIG.

(Embodiment 1) FIG. 1 is a plan view (a) showing a first embodiment of a heat-sensitive flow sensor according to the present invention, and a schematic cross-sectional view (b) taken along line AA thereof.

The thermal flow sensor 1 according to the present embodiment
A thin film of an insulating layer 3 is formed on the surface of a semiconductor substrate 2, and a heater 11, an upstream temperature measuring resistor 12 as a first temperature sensor and a downstream temperature measuring device as a second temperature sensor are formed thereon. It has a configuration in which the thermal resistor 13 is formed.

Further, the lower portion of the heater portion 11 of the semiconductor substrate 2 is removed from the surface side by etching to form the first void portion 4a, and the lower portion of the upstream temperature measuring resistor 12 is removed from the surface side by etching. To form the second gap 4b, and remove the lower part of the downstream-side resistance thermometer 13 from the surface side by etching to thereby form the third gap 4b.
c is formed.

For this reason, the heater portion 11 includes a bridge portion 5 a in which a part of the insulating layer 3 is formed on the semiconductor substrate 2 in a cross-linked manner.
The upstream side resistance thermometer 12 is formed on the bridge portion 5 b in which a part of the insulating layer 3 is formed in a bridge on the semiconductor substrate 2.
The downstream temperature measuring resistor 13 is formed on a bridge portion 5c in which a part of the insulating layer 3 is formed in a bridge on the semiconductor substrate 2.
It has the configuration formed above.

As a method of manufacturing the heat-sensitive flow sensor 1, first, a thin insulating layer 3 made of, for example, silicon oxide SiO2 is formed on a surface of a semiconductor substrate 2 made of a silicon substrate having a high thermal conductivity. Then, afterwards, the semiconductor substrate 2
Is formed on the insulating layer 3.

Next, a heater 11, an upstream temperature measuring resistor 12 and a downstream temperature measuring resistor 13 are formed on the insulating layer 3. Then, the heater unit 11 and the upstream-side resistance temperature detector 12
And the silicon oxide S
A protective film made of iO2 is formed.

Next, a wire pad 11 is formed on the protective film.
A contact hole such as a and 11b and a pattern for etching the semiconductor substrate 2 are formed, and the semiconductor substrate 2 is etched to form voids 4a to 4c.

In this configuration, the wire pads 11a,
When a current is passed between the heater portions 11b to cause the heater portion 11 to generate heat, part of the heat generated from the heater portion 11 is transmitted to the upstream temperature measuring resistor 12 through the insulating layer 3 constituting the bridge portion 5a. However, since the semiconductor substrate 2 remaining between the gaps 4a and 4b is formed of a silicon substrate having a high thermal conductivity, the semiconductor substrate 2 functions as a heat sink, and the heat from the heater 11 is transferred to the upstream temperature measuring resistor. It prevents conduction to the body 12.

Similarly, a part of the heat generated from the heater portion 11 is conducted to the downstream temperature measuring resistor 13 side through the insulating layer 3 constituting the bridge portion 5a, but the gap portion 4a and the gap portion 4c are formed.
The semiconductor substrate 2 remaining between the two functions as a heat sink to prevent heat from the heater 11 from being conducted to the downstream temperature measuring resistor 13.

As described above, the semiconductor substrate 2 having a high thermal conductivity is left without being etched between the heater portion 11 and the upstream temperature measuring resistor 12 and between the heater portion 11 and the downstream temperature measuring resistor 13. Thereby, the heat generated in the heater section 11 is absorbed by the semiconductor substrate 2, and the conduction of the heat to the upstream-side resistance temperature detector 12 and the downstream-side resistance temperature detector 13 can be suppressed. A heat-sensitive flow sensor can be provided.

(Embodiment 2) FIG. 2 is a plan view (a) showing a heat-sensitive flow sensor according to Embodiment 2 of the present invention, and a schematic cross-sectional view taken along the line BB of FIG.

The thermal flow sensor 1 according to the present embodiment
Is placed on the insulating layer 3 formed on the surface of the semiconductor substrate 2 as a thin film.
It has a configuration in which a heater section 11, an upstream temperature measuring resistor 12, and a downstream temperature measuring resistor 13 are formed, and a portion below the upstream temperature measuring resistor 12 and below the downstream temperature measuring resistor 13 of the semiconductor substrate 2. Is removed from the surface side by etching to form a void portion 4, and a metal having a high thermal conductivity is provided as the first and second heat absorbers 6 a and 6 b in the void portion 4. It has a configuration.

The first heat absorber 6a is installed between the heater section 11 and the upstream resistance temperature detector 12, and the second heat absorber 6b
Is installed between the heater section 11 and the downstream-side resistance thermometer 13. Due to this configuration, the heater section 11 is formed on the bridge section 5a in which a part of the insulating layer 3 is formed in a bridge between the heat absorber 6a and the heat absorber 6b.
Is formed on a bridge portion 5b in which a part of the insulating layer 3 is formed in a bridge between the semiconductor substrate 2 and the heat absorber 6a. Bridge portion 5 formed in a cross-linking manner between substrate 2 and heat absorber 6b
c.

In this configuration, the wire pads 11a,
When a current is passed between the heater portions 11b to cause the heater portion 11 to generate heat, part of the heat generated from the heater portion 11 is transmitted to the upstream temperature measuring resistor 12 through the insulating layer 3 constituting the bridge portion 5a. However, the heat absorber 6a provided between the heater unit 11 and the upstream resistance temperature detector 12 functions as a heat sink, and the heat from the heater unit 11 is conducted to the upstream resistance temperature detector 12. prevent.

A part of the heat generated from the heater 11 is conducted to the downstream temperature measuring resistor 13 through the insulating layer 3 constituting the bridge portion 5a. The heat absorber 6b provided between them serves as a heat sink, preventing heat from the heater 11 from being conducted to the downstream temperature measuring resistor 13.

By providing the heat absorbers 6a and 6b having a high thermal conductivity in the space 4, the heat generated in the heater 11 is absorbed by the heat absorbers 6a and 6b, and the upstream side temperature measurement is performed. Conduction to the resistor 12 and the downstream temperature measuring resistor 13 can be suppressed, and a highly sensitive thermosensitive flow sensor can be provided.

(Embodiment 3) FIG. 3 is a plan view (a) showing a heat-sensitive flow sensor according to Embodiment 3 of the present invention, and a schematic cross-sectional view taken along line CC of FIG.

The thermal flow sensor 1 according to the present embodiment
Is placed on the insulating layer 3 formed on the surface of the semiconductor substrate 2 as a thin film.
The area from the heater 11, the upstream resistance thermometer 12, and the downstream resistance thermometer 13 to the upstream resistance thermometer 12 of the semiconductor substrate 2 to the downstream resistance thermometer 13 is defined by:
The space portion 4 is formed by removing the surface of the semiconductor substrate 2 by etching, but a portion of the semiconductor substrate 2 is left in the space portion 4 without being etched as the columnar groups 2a and 2b.

With this configuration, the heater section 11, the upstream temperature measuring resistor 12, and the downstream temperature measuring resistor 13 are formed on the bridge section 5 in which a part of the insulating layer 3 is formed in a cross-linked shape. . The column group 2a includes the heater 11 and the upstream-side resistance thermometer 1.
2 and a plurality of columnar bodies formed of the semiconductor substrate 2 left between the heaters 11 and the plurality of semiconductor substrates 2 left between the heater unit 11 and the downstream temperature measuring resistor 13. It consists of pillars.

In this configuration, the wire pads 11a,
When an electric current is passed between 11b and the heater unit 11 generates heat, a part of the heat generated from the heater unit 11 is transmitted to the upstream temperature measuring resistor 12 side through the insulating layer 3 constituting the bridge unit 5. However, the column group 2a provided between the heater 11 and the upstream resistance temperature detector 12 functions as a heat sink, absorbs heat from the heater 11 and conducts the heat to the upstream resistance temperature detector 12. It is prevented from being done.

A part of the heat generated from the heater portion 11 is conducted to the downstream temperature measuring resistor 13 through the insulating layer 3 constituting the bridge portion 5. The column group 2b installed between the two serves as a heat sink, preventing heat from the heater section 11 from being conducted to the downstream temperature measuring resistor 13.

By disposing a part of the semiconductor substrate 2 having a high thermal conductivity in the gap 4 as the column groups 2a and 2b, the heat generated by the heater 11 can be removed from the column groups 2a and 2b.
b, and can be prevented from being transmitted to the upstream-side resistance temperature detector 12 and the downstream-side resistance temperature detector 13, thereby providing a highly sensitive thermosensitive flow sensor.

The column groups 2a and 2b are not limited to the silicon substrate constituting the semiconductor substrate 2, but may be made of, for example, the metal having high thermal conductivity described in the second embodiment.
2b may be used.

(Embodiments 4 to 6) FIGS. 4A and 4B are a plan view and a schematic cross-sectional view taken along a line DD of a heat-sensitive flow sensor according to a fourth embodiment of the present invention. .

The thermal flow sensor 1 according to the present embodiment
Is placed on the insulating layer 3 formed on the surface of the semiconductor substrate 2 as a thin film.
A heater section 11, an upstream temperature measuring resistor 12, and a downstream temperature measuring resistor 13 are formed, and the upstream temperature measuring resistor 12 of the semiconductor substrate 2 is formed.
From the surface to the downstream-side resistance thermometer 13 by etching away from the surface side to form the gap portion 4, and the insulating layer 3 on the gap portion 4 is formed in a bridge-like shape as the bridge portion 5. have.

A heat absorbing layer 14a is formed between the heater section 11 on the bridge section 5 and the upstream temperature measuring resistor 12 by vapor deposition of a metal having a high heat capacity. A heat absorbing layer 14b is formed between the temperature measuring resistor 13 and a metal having a high heat capacity by vapor deposition.

In this configuration, the wire pads 11a,
When an electric current is passed between 11b and the heater unit 11 generates heat, a part of the heat generated from the heater unit 11 is transmitted to the upstream temperature measuring resistor 12 side through the insulating layer 3 constituting the bridge unit 5. However, the heat absorbing layer 14a provided between the heater 11 and the upstream resistance temperature detector 12 functions as a heat sink, and absorbs heat from the heater 11 and conducts the heat to the upstream resistance temperature detector 12. Is restrained.

A part of the heat generated from the heater portion 11 is conducted to the downstream temperature measuring resistor 13 through the insulating layer 3 constituting the bridge portion 5. The heat absorbing layer 14b provided between the two functions as a heat sink to prevent the heat from the heater 11 from being transmitted to the downstream temperature measuring resistor 13.

As described above, the heater section 11 on the bridge section 5
And vapor-depositing a heat-absorbing layer 14a having high thermal conductivity between the upstream resistance thermometer 12 and vapor-depositing a heat-absorbing layer 14b having high thermal conductivity between the heater 11 and the downstream resistance thermometer 13. The heat generated by the heater 11 is transferred to the heat absorbing layer 14.
a, 14b, and can be prevented from being transmitted to the upstream temperature measuring resistor 12 and the downstream temperature measuring resistor 13.

Further, as shown in FIG. 5, the heat absorbing layers 14a and 14b are extended and deposited on the semiconductor substrate 2 outside the bridge portion 5 as the fifth embodiment, so that a semiconductor constituted by a silicon substrate is formed. Since the substrate 2 has a high thermal conductivity, heat transmitted from the heater section 11 through the insulating layer 3 forming the bridge section 5 is transmitted to the semiconductor substrate 2 through the heat absorbing layers 14a and 14b, and measured upstream from the heater section 11. The heat flowing into the temperature resistor 12 and the downstream temperature sensor 13 can be further suppressed.

As shown in FIG. 6 according to the sixth embodiment, if the shape of the heat absorbing layers 14a and 14b is vapor-deposited in a bow shape which is curved inward, contrary to the isothermal curve of the temperature distribution from the heater section 11. In addition, the flow of heat into the upstream temperature measuring resistor 12 and the downstream temperature measuring resistor 13 can be suppressed in accordance with the temperature distribution from the heater section 11.

That is, since the isothermal curve of the temperature distribution from the heater section 11 has an elliptical shape, the temperature is high in the central portion of the heater portion 11 and low in the peripheral portion. Therefore, the heat absorbing layer 14
By forming the shapes of a and 14b in an arcuate shape warped inward so as to approach the center of the heater portion 11 having a high temperature,
It absorbs a lot of heat in the center and corrects the elliptical isothermal curve to a straight line.

Incidentally, also in this example, the heat absorbing layers 14a, 1
4b is extended over the semiconductor substrate 2 outside the bridge portion 5 as shown by a broken line, the heat generated in the heater portion 11 is transmitted to the semiconductor substrate 2 through the heat absorbing layers 14a and 14b, and the upstream temperature measuring resistor Body 12 and downstream resistance temperature detector 13
Can further be suppressed.

[0059]

According to the first aspect of the present invention, the first to third gaps are provided on the surface of the semiconductor substrate, and the gap is provided between the heater and the first temperature sensor, and between the heater and the second temperature sensor. By leaving the semiconductor substrate between the first and second temperature sensor portions, heat generated in the heater portion and transmitted through the insulating layer is absorbed by the semiconductor substrate and is transmitted to the first and second temperature sensor portions. This has an advantageous effect of suppressing the occurrence of the above.

According to the second aspect of the present invention, the lower portion between the heater portion and the first temperature sensor portion and the lower portion between the heater portion and the second temperature sensor portion are formed in the gap provided on the surface of the semiconductor substrate. By installing a heat absorber having a high thermal conductivity at the lower portion between the first and second heat absorbers, heat generated in the heater portion and transmitted through the insulating layer is absorbed by the heat absorber, and the first and second heat absorbers are absorbed. An advantageous effect that conduction to the temperature sensor section can be suppressed can be obtained.

According to the third aspect of the present invention, the lower portion between the heater portion and the first temperature sensor portion and the lower portion between the heater portion and the second temperature sensor portion are formed in the gap provided on the surface of the semiconductor substrate. By installing a plurality of columnar heat absorbers each having a high thermal conductivity in the lower part between the first and second heat absorbers, the heat generated in the heater portion and transmitted through the insulating layer is absorbed by the heat absorbers, and Further, the advantageous effect that conduction to the second temperature sensor unit can be suppressed can be obtained.

According to the fourth aspect of the present invention, the first and second heat absorbing layers are disposed on the insulating layer between the heater and the first and second temperature sensors, respectively. The heat transmitted through the insulating layer is applied to the first and second
This has the advantageous effect of suppressing absorption by the heat absorbing layer and conduction to the first and second temperature sensor portions.

[Brief description of the drawings]

FIG. 1A is a plan view showing a first embodiment of a thermal flow sensor according to the present invention, and FIG. 1B is a schematic sectional view taken along line AA.

FIGS. 2A and 2B are a plan view and a schematic cross-sectional view taken along line BB of a second embodiment of a thermal flow sensor according to the present invention. FIGS.

FIGS. 3A and 3B are a plan view and a schematic cross-sectional view taken along line CC of a heat-sensitive flow sensor according to a third embodiment of the present invention.

FIG. 4 is a plan view (a) showing a fourth embodiment of a thermal flow sensor according to the present invention, and a schematic cross-sectional view thereof along line DD (b).

FIG. 5 is a plan view showing a heat-sensitive flow sensor according to a fifth embodiment of the present invention.

FIG. 6 is a plan view showing a sixth embodiment of a thermal flow sensor according to the present invention.

FIG. 7A is a plan view showing a conventional heat-sensitive flow sensor.
FIG. 4B is a schematic cross-sectional view (b) of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal-sensitive flow sensor 2 Semiconductor substrate 2a, 2b Heat absorber 3 Insulating layer 4, 4a-4c Air gap 5, 5a-5c Bridge part 6a, 6b Heat absorber 11 Heater part 11a, 11b Wire pad 12 Upstream temperature measurement Resistor 12a, 12b Wire pad 13 Downstream temperature measuring resistor 13a, 13b Wire pad 14a, 14b Heat absorbing layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Masaaki Sasaki 10F, Hanazono Todocho, Ukyo-ku, Kyoto City, Kyoto Prefecture F-term (reference) 2F035 EA04 EA08

Claims (6)

[Claims] An insulating layer formed in a thin film on the surface of a semiconductor substrate; a heater disposed on the surface of the insulating layer; and an insulating layer on the upstream and downstream sides of the fluid centered on the heater. First and second temperature sensor portions disposed on the surface of the layer; and the semiconductor substrate facing the heater portion and the first and second temperature sensor portions so as to open to the front surface side of the semiconductor substrate. First to third voids formed in
A thermo-sensitive flow sensor comprising: 2. An insulating layer formed in a thin film on the surface of a semiconductor substrate; a heater disposed on the surface of the insulating layer; and the insulation on the upstream and downstream sides of the fluid centered on the heater. First and second temperature sensor portions disposed on the surface of the layer; and an opening on the front surface side of the semiconductor substrate facing a region from the first temperature sensor portion to the second temperature sensor portion. A gap formed in the semiconductor substrate, a first heat absorber disposed in the gap so as to face a region between the heater and the first temperature sensor, and the heater. And a second heat absorber disposed in the gap portion facing the region between the second temperature sensor portions,
A thermo-sensitive flow sensor comprising: 3. An insulating layer formed in a thin film on the surface of a semiconductor substrate, a heater disposed on the surface of the insulating layer, and the insulation on the upstream and downstream sides of the fluid with the heater as a center. First and second temperature sensor portions disposed on the surface of the layer; and an opening on the front surface side of the semiconductor substrate facing a region from the first temperature sensor portion to the second temperature sensor portion. A gap formed in the semiconductor substrate, and a plurality of columnar first heat absorbers installed in the gap facing the region between the heater and the first temperature sensor. A plurality of columnar second heat absorbers installed in the gap portion facing the region between the heater portion and the second temperature sensor portion. . 4. An insulating layer formed in a thin film on the surface of a semiconductor substrate, a heater disposed on the surface of the insulating layer, and the insulation on the upstream and downstream sides of the fluid centered on the heater. First and second temperature sensor portions disposed on the surface of the layer; and an opening on the front surface side of the semiconductor substrate facing a region from the first temperature sensor portion to the second temperature sensor portion. A void formed in the semiconductor substrate, a first heat absorbing layer disposed between the heater and the first temperature sensor on the surface of the insulating layer, A second heat absorbing layer disposed between the heater section and the second temperature sensor section. 5. The heat-sensitive flow sensor according to claim 4, wherein said first and second heat absorbing layers are provided to extend over said semiconductor substrate. -Sensors. 6. The heat-sensitive flow according to claim 4 or 5.
In the sensor, the first and second heat-absorbing layers are installed in a bow shape that is curved inward in an opposite direction to an isothermal curve of a temperature distribution of heat from the heater. .