阅读说明：本技术 一种风速传感器及其制备方法 (Wind speed sensor and preparation method thereof ) 是由 李以贵 袁泉 张成功 金敏慧 于 2020-05-29 设计创作，主要内容包括：本发明涉及一种风速传感器,包括位于密闭空间的测速单元,所述测速单元包括位于密闭空间内的T型加热器和测温传感器；所述T型加热器为T型结构,该T型结构的横部两端分别设有两个加热电阻；所述测温传感器围绕设于所述T型结构的外侧,并且在位于所述T型结构的中间竖部两侧的位置分别设有两个测温电阻；以T型结构的中间竖部为对称轴,所述两个加热电阻呈对称放置,两个测温电阻呈对称设置。与现有技术相比,本发明具有传感器体积小、灵敏度高、实用性强等优点。(The invention relates to an air speed sensor which comprises a speed measuring unit positioned in a closed space, wherein the speed measuring unit comprises a T-shaped heater and a temperature measuring sensor which are positioned in the closed space; the T-shaped heater is of a T-shaped structure, and two ends of the transverse part of the T-shaped structure are respectively provided with two heating resistors; the temperature measuring sensor is arranged on the outer side of the T-shaped structure in a surrounding manner, and two temperature measuring resistors are respectively arranged at the positions of two sides of the middle vertical part of the T-shaped structure; the middle vertical part of the T-shaped structure is taken as a symmetry axis, the two heating resistors are symmetrically arranged, and the two temperature measuring resistors are symmetrically arranged. Compared with the prior art, the invention has the advantages of small sensor volume, high sensitivity, strong practicability and the like.)

1. A wind speed sensor comprises a speed measuring unit positioned in a closed space, and is characterized in that the speed measuring unit comprises a T-shaped heater (1) and a temperature measuring sensor (2) which are positioned in the closed space; the T-shaped heater (1) is of a T-shaped structure, and two ends of the transverse part of the T-shaped structure are respectively provided with two heating resistors; the temperature measuring sensor (2) is arranged on the outer side of the T-shaped structure in a surrounding manner, and two temperature measuring resistors are respectively arranged at the positions of two sides of the middle vertical part of the T-shaped structure; the middle vertical part of the T-shaped structure is taken as a symmetry axis, the two heating resistors are symmetrically arranged, and the two temperature measuring resistors are symmetrically arranged.

2. A wind speed sensor according to claim 1, wherein the heating resistor is a thermite resistor.

3. A wind speed sensor according to claim 2, wherein the thickness of the thermite resistor is 2 to 20 μm.

4. A wind speed sensor according to claim 2, wherein the T-shaped heater (1) is made of an SOI substrate, and the thermite resistor is bonded to a surface silicon layer of the SOI substrate.

5. A wind speed sensor according to claim 1, wherein the temperature sensor (2) is made of an SOI substrate, and the temperature measuring resistor is a thermistor obtained by ion implantation of surface silicon of the SOI substrate; the thickness of the thermistor is 2-20 mu m.

6. The wind speed sensor according to claim 1, wherein the distance between the heating resistor and the temperature measuring resistor located on both sides of the symmetry axis along the extending direction of the transverse portion of the T-shaped structure is 10-20 μm.

7. A wind speed sensor according to claim 1, wherein the T-shaped heater (1) is of cantilever beam construction.

8. An anemometric sensor according to claim 1, comprising two X-direction tachometer units for measuring acceleration in the X-direction and two Y-direction tachometer units for measuring acceleration in the Y-direction, wherein the lateral portion of the T-shaped structure of each tachometer unit is parallel to the corresponding measuring direction of the anemometer unit.

9. A method for manufacturing a wind speed sensor according to any of claims 1 to 8, comprising the steps of:

(S-1) preparing an SOI substrate with a three-layer structure, and forming a silicon dioxide film on the surface silicon of the SOI substrate through a thermal oxidation process;

(S-2) removing the silicon dioxide film at the heating resistor and the temperature measuring resistor pattern by a sputtering process to expose the surface silicon of the SOI substrate;

(S-3) doping boron ions in the surface silicon of the temperature measuring resistor pattern by a diffusion method to form a temperature measuring resistor;

(S-4) etching electrode patterns on the surface silicon corresponding to the temperature measuring resistor and the heating resistor by a photoetching process;

(S-5) forming an aluminum layer on the silicon surface of the SOI substrate through magnetron sputtering, spin-coating photoresist, exposing, developing and etching to obtain a pattern of a heating resistor, a pattern of an upper electrode of a temperature measuring resistor and a lead pattern;

(S-6) etching the back surface to release a cantilever beam structure of the T-shaped heater (1) and the temperature measuring sensor (2) to obtain the speed measuring unit, and mounting the speed measuring element in a closed cavity formed by the silicon substrate and the top packaging cover to obtain the wind speed sensor.

10. The method for manufacturing a wind speed sensor according to claim 9, wherein in the manufacturing process, when the heating resistor and the temperature measuring resistor are processed, the heating resistor and the temperature measuring resistor on one side of the T-shaped structure are processed, and the heating resistor and the temperature measuring resistor on the other side of the T-shaped structure are processed.

Technical Field

The invention relates to the technical field of wind speed sensors, in particular to a wind speed sensor and a preparation method thereof.

Background

The fluid can not be separated in various fields of meteorology, environmental protection, aerospace, aviation, daily life and the like. The methods for measuring the fluid are various, and the measurement conditions are basically the same for the measurement of the gas, and it is particularly critical to select an appropriate measurement method. The traditional wind speed sensor has the defects of large volume, high possibility of being influenced by environmental temperature and pressure, poor stability and the like, and the application of the traditional wind speed sensor is limited to a great extent; and the sensitivity of the traditional sensor is not high, so that the measurement result error is high, and the effect in practical application is poor.

Chinese patent CN 107192849a discloses a design and a manufacturing method of a micro-mechanical acceleration sensor based on the heat convection principle. The invention relates to a heat convection type micro-mechanical acceleration sensor, wherein a hole is not formed on a silicon chip to form a cavity structure, but a glass cover plate and the silicon chip are bonded by BCB bonding glue to form a closed cavity, a polyimide film is manufactured on a first substrate to prevent heat dissipation, so that a hot gas mass can better play a role and reduce power consumption, and the polyimide film can also prevent a platinum electrode from electric leakage; however, the sensitivity of the acceleration sensor of the patent technology needs to be improved, and the acceleration sensor cannot be applied to measurement of wind speed at low wind speed.

Disclosure of Invention

The invention aims to overcome the defect of low sensitivity in the prior art, and provides a wind speed sensor and a preparation method thereof, which can improve the measurement accuracy in the application scene of measuring low wind speed.

The purpose of the invention can be realized by the following technical scheme:

a wind speed sensor comprises a speed measuring unit positioned in a closed space, wherein the speed measuring unit comprises a T-shaped heater and a temperature measuring sensor which are positioned in the closed space; the T-shaped heater is of a T-shaped structure, and two ends of the transverse part of the T-shaped structure are respectively provided with two heating resistors; the temperature measuring sensor is arranged on the outer side of the T-shaped structure in a surrounding manner, and two temperature measuring resistors are respectively arranged at the positions of two sides of the middle vertical part of the T-shaped structure; the middle vertical part of the T-shaped structure is taken as a symmetry axis, the two heating resistors are symmetrically arranged, and the two temperature measuring resistors are symmetrically arranged.

The invention applies an SOI substrate structure to the wind speed sensor, and the wind speed sensor prepared by adopting the silicon SOI substrate as the substrate has good speed measuring performance, is not easily influenced by the environmental temperature and pressure, and has good stability.

The invention designs a three-layer SOI substrate structure with a heating resistor and a temperature measuring resistor based on a wind speed measuring method of constant temperature difference of a heat conduction principle, which mainly comprises two heating resistors, two completely same sensing resistors and a closed cavity consisting of a silicon substrate and a top packaging cover, wherein the heating resistors are placed in the centers of two ends of the closed cavity and are connected by a cantilever beam; the two sensing resistors are symmetrically arranged on two sides of the cantilever beam perpendicular to the cantilever beam where the heating resistor is arranged and symmetrically distributed along the central axis of the T-shaped heater, namely the T-shaped heater is wrapped by the U-shaped temperature measuring sensor. When the heating resistors are electrified and start to work, air in the closed cavity is heated to form a hot air mass which can serve as a sensitive mass block, when the wind speed is 0, the hot air mass is at a constant position, the temperature field in the cavity is stable, the temperatures sensed by the two temperature measuring resistors are the same, the resistors are also the same in size, and no signal output can be detected through a detection circuit externally connected with the lead wire area; when wind speed in a sensitive direction is applied to the sensor, the position of the hot air mass relative to the plurality of thermal resistors is changed, the temperature sensed by the two sensing resistors is changed, and the resistance value of the two sensing resistors is changed. Therefore, a differential signal can be detected through an external detection circuit, and a direct current voltage signal, namely the detected wind speed signal, is finally output after processing. The required wind speed data can be obtained by reading the direct current voltage signal.

The heating resistor is a thermite resistor.

The thickness of the thermite resistor is 2-20 mu m, preferably 5 mu m.

The T-shaped heater is made of an SOI substrate, and the thermite resistor is attached to a surface silicon layer of the SOI substrate.

The temperature sensor is made of an SOI substrate, and the temperature measuring resistor is a thermistor obtained by ion implantation of surface silicon of the SOI substrate.

The thickness of the thermistor is 2-20 μm, preferably 5 μm.

And along the extension direction of the transverse part of the T-shaped structure, the distance between the heating resistor and the temperature measuring resistor which are positioned at two sides of the symmetry axis is 10-20 mu m.

The silicon has the characteristics of good characteristics, easy preparation, mature processing technology, crystal face anisotropy which is very useful for mechanical processing, capability of integrating an active circuit and the like, so the silicon is selected as a temperature measuring resistance material; the metal Al has the advantages of low melting point, good ductility, small errors of performance temperature and temperature coefficient, and the like, so the metal Al is selected as the heating resistance material. And the thickness of the SOI substrate is in the micrometer level, so that the SOI substrate has extremely high flexibility and ductility, and can be applied to various scenes.

The T-shaped heater is of a cantilever beam structure.

The wind speed sensor comprises two X-direction speed measuring units for measuring the acceleration in the X direction and two Y-direction speed measuring units for measuring the acceleration in the Y direction, wherein the T-shaped structure transverse part of each speed measuring unit is parallel to the measuring direction corresponding to the speed measuring unit.

The preparation method of the wind speed sensor comprises the following steps:

(S-1) preparing an SOI substrate with a three-layer structure, and forming a silicon dioxide film on the surface silicon of the SOI substrate through a thermal oxidation process;

(S-2) removing the silicon dioxide film at the heating resistor and the temperature measuring resistor pattern by a sputtering process to expose the surface silicon of the SOI substrate;

(S-3) doping boron ions in the surface silicon of the temperature measuring resistor pattern by a diffusion method to form a temperature measuring resistor;

(S-4) etching electrode patterns on the surface silicon corresponding to the temperature measuring resistor and the heating resistor by a photoetching process;

(S-5) forming an aluminum layer on the silicon surface of the SOI substrate through magnetron sputtering, spin-coating photoresist, exposing, developing and etching to obtain a pattern of a heating resistor, a pattern of an upper electrode of a temperature measuring resistor and a lead pattern;

(S-6) etching the back surface to release a cantilever beam structure of the T-shaped heater and the temperature measuring sensor to obtain the speed measuring unit, and mounting the speed measuring element in a closed cavity formed by the silicon substrate and the top packaging cover to obtain the wind speed sensor.

When the heating resistor and the temperature measuring resistor are processed, the heating resistor and the temperature measuring resistor which are positioned on one side of the T-shaped structure are processed firstly, and then the heating resistor and the temperature measuring resistor which are positioned on the other side of the T-shaped structure are processed.

Compared with the prior art, the invention has the following advantages:

(1) the sensor adopting the SOI substrate material has small volume, high precision and good ductility, can be well applied to various scenes, is simple to install and can be better applied to actual operation;

(2) the sensitivity and the frequency response of the sensor are improved and the power consumption is reduced by reasonably setting the structure of the resistor;

(3) the heating resistors are arranged on two sides, the temperature measuring resistors are positioned in the middle and are distributed at a short distance, and the temperature measuring resistors are positioned in the middle; the design reduces heat loss, heat conduction of the device, heat capacity of the device, heating power and stress.

(4) The temperature distribution of the invention is changed due to the change of the position of the heater, and the sensitivity of the invention is improved because the volume of the sensor is very small, and the distance between the heating resistor and the temperature measuring resistor is very close, so the response time is very short, and the invention is sensitive to the temperature change.

(5) The heating element of the invention can strictly ensure that the difference between the internal temperature of the speed measuring element and the external environment temperature is kept constant, thereby improving the sensitivity to the environment temperature and improving the measuring precision.

Drawings

FIG. 1 is a schematic structural diagram of a velocity measurement device according to the present invention;

FIG. 2 is a schematic structural view of the material of each layer of the SOI substrate according to the present invention;

FIG. 3 is a schematic view of a heating resistor according to the present invention;

FIG. 4 is a schematic structural diagram of a temperature measuring resistor according to the present invention;

FIG. 5 is a schematic view of the structure of the wind speed sensor of the present invention;

in the figure, 1 is a T-shaped heater, 2 is a temperature measuring sensor, 3 is a position of a heating resistor, 4 is a position of a temperature measuring resistor, 5 is a cantilever beam, 6 is (110) silicon, 7 is silicon dioxide based on (111) silicon, 8 is (112) silicon, 9 is a both-end electrode of the heating resistor, 10 is a both-end electrode of the temperature measuring resistor, 11 is a lead wire of the heating resistor, and 12 is a lead wire of the temperature measuring resistor.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.