阅读说明：本技术 二维温度平衡模式mems风速风向传感器及其制备方法 (Two-dimensional temperature balance mode MEMS wind speed and direction sensor and preparation method thereof ) 是由 易真翔 谢雨珏 秦明 黄庆安 于 2021-07-19 设计创作，主要内容包括：本发明公开了一种二维温度平衡模式MEMS风速风向传感器及其制备方法,传感器包括传感器芯片部分和测控电路,传感器芯片部分基于热电偶结构,测控电路系统采用温度平衡模式。芯片中的测温元件热电偶由两层热偶臂组成。基于分时复用的思想,持续采样x和y方向上的输出电压,利用控制电路调整4个加热元件上的功耗,使得x和y方向上、下游温差为零。最终,根据4个加热元件的功耗值即可获取风速和风向信息。相较于现有技术,该传感器结构提出了新的基于热电偶的二维风速风向传感结构与检测过程,此外,解决了垂直方向热偶臂交叉互连问题,在实现多层热电堆测温时有减少材料层数与优化制备工艺的优势。(The invention discloses a two-dimensional temperature balance mode MEMS wind speed and direction sensor and a preparation method thereof. The temperature measuring element thermocouple in the chip consists of two layers of thermocouple arms. Based on the idea of time division multiplexing, output voltages in the x and y directions are continuously sampled, and power consumption of 4 heating elements is adjusted by a control circuit, so that the temperature difference between the upstream and the downstream in the x and y directions is zero. Finally, the wind speed and direction information can be obtained according to the power consumption values of the 4 heating elements. Compared with the prior art, the sensor structure provides a novel two-dimensional wind speed and direction sensing structure and a detection process based on the thermocouple, in addition, the problem of cross interconnection of thermocouple arms in the vertical direction is solved, and the advantages of reducing the number of material layers and optimizing the preparation process are achieved when the temperature of the multilayer thermopile is measured.)

1. A two-dimensional temperature balance mode MEMS wind speed and direction sensor is characterized by comprising a sensor chip part and a measurement and control circuit, wherein the sensor chip part comprises a substrate (1), heating elements (2), temperature measuring elements and metal contact electrodes (6), and the four heating elements (2) are symmetrically distributed around the center of a chip and used for forming a symmetrical temperature distribution field on the surface of the chip; the temperature measuring element is composed of a first thermopile distributed along the N-S direction and a second thermopile distributed along the W-E direction which are mutually orthogonal, and the first thermopile and the second thermopile are respectively composed of a lower material A thermocouple arm (3) and an upper material B thermocouple arm (5); the first thermopile, the second thermopile and the four heating elements (2) are respectively connected with two metal contact electrodes (6); the measurement and control circuit comprises a signal amplification circuit and a heating power control circuit, the signal amplification circuit is used for amplifying output signals of the first thermopile and the second thermopile and then inputting the heating power control circuit, the heating power control circuit is used for carrying out power control on the heating element so as to realize zero output of the two thermopiles and achieve a temperature balance state.

2. The two-dimensional temperature balanced mode MEMS wind speed and direction sensor according to claim 1, characterized in that the heating power control circuit controls the switching on and off of one group of heating elements (2) distributed along the N-S direction and another group of heating elements (2) distributed along the W-E direction by time-division multiplexing circuits.

3. A method for manufacturing a two-dimensional temperature balanced mode MEMS wind speed and direction sensor, wherein the two-dimensional temperature balanced mode MEMS wind speed and direction sensor is as claimed in claim 1 or 2, the method comprising the steps of:

step 1: preparing an oxide layer on a substrate (1); then depositing, photoetching and etching polysilicon to form a heating element (2), a material A thermocouple arm (3) and a contact block;

step 2: depositing an insulating layer (4) on the basis of step 1; then depositing, photoetching and etching metal to form a material B thermocouple arm (5) and a contact block;

and step 3: depositing a metal on the basis of step 2; then stripping to form a metal contact electrode (6).

Technical Field

The invention discloses a two-dimensional temperature balance mode MEMS wind speed and direction sensor based on a thermocouple structure, and belongs to the technical field of measurement and testing.

Background

The method for effectively and timely acquiring the wind speed and wind direction information is very important in the life and production fields of traffic transportation, meteorological monitoring, wind power generation, agricultural production and the like. Based on different measurement principles, wind speed and direction sensors can be roughly classified into mechanical type, ultrasonic type and thermal type. The mechanical type is high in maintenance cost due to mechanical abrasion, the ultrasonic type is difficult to miniaturize due to the limitation of a measurement principle, the thermal sensor measures wind speed information by utilizing the temperature distribution change of the surface of a device caused by the fact that fluid flows through the surface of the device to generate thermal convection, and the problems can be avoided by combining with the MEMS technology, so that the thermal sensor has a huge application prospect.

In 1823, Seebeck, a German physicist, found the "Seebeck effect", which means that two different conductors form a loop, and when the temperatures of the two nodes are different, a voltage is generated in the loop. The relationship between the voltage difference of the loop and the temperature difference between two nodes can be expressed asWherein alpha is_A、α_BSeebeck coefficient of material A, B, T, T respectively₀The temperature difference between the two nodes can be measured by knowing the voltage difference of the measured loop. Compared with thermal resistance, the output of the thermocouple has no offset and drift, and no voltage is needed, so that the thermocouple has unique advantages in the field of temperature difference measurement.

Chinese patent 2017114707670 discloses a wind speed and direction sensor based on double-layer thermopile structure and a detection method, the sensor includes a heating resistor, an upper-layer thermopile group, a lower-layer thermopile group, the heating resistor is located in the center of a substrate, the lower-layer thermopile group includes first to fourth lower-layer thermopiles arranged around the heating resistor, the upper-layer thermopile group includes first to fourth upper-layer thermopiles, and upper and lower contact blocks are connected to each thermopile in the lower-layer thermopile group. However, the preparation of the double-layer thermopile requires growth and etching of four layers of material layers, and the preparation process is complex; in addition, in order to realize the measurement of two-dimensional wind speed and wind direction, the structure adopts 8 thermopiles, 16 contact blocks are connected with the thermopiles to output 8 groups of voltage signals, and the measuring and calculating process is complex.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the prior art, a two-dimensional temperature balance mode MEMS wind speed and direction sensor and a preparation method thereof are provided, and the problem of complex process of the wind speed and direction sensor based on a thermocouple structure temperature balance mode is solved.

The technical scheme is as follows: a two-dimensional temperature balance mode MEMS wind speed and direction sensor comprises a sensor chip part and a measurement and control circuit, wherein the sensor chip part comprises a substrate, heating elements, temperature measuring elements and metal contact electrodes, and the four heating elements are symmetrically distributed around the center of a chip and used for forming a symmetrical temperature distribution field on the surface of the chip; the temperature measuring element is formed by mutually orthogonalizing a first thermopile distributed along the N-S direction and a second thermopile distributed along the W-E direction, and the first thermopile and the second thermopile respectively consist of a lower-layer material A thermocouple arm and an upper-layer material B thermocouple arm; the first thermopile, the second thermopile and the four heating elements are respectively connected with two metal contact electrodes; the measurement and control circuit comprises a signal amplification circuit and a heating power control circuit, the signal amplification circuit is used for amplifying output signals of the first thermopile and the second thermopile and then inputting the heating power control circuit, the heating power control circuit is used for carrying out power control on the heating element so as to realize zero output of the two thermopiles and achieve a temperature balance state.

Further, the heating power control circuit controls the on and off of one group of heating elements distributed along the N-S direction and the other group of heating elements distributed along the W-E direction through a time division multiplexing circuit.

A preparation method of a two-dimensional temperature balance mode MEMS wind speed and direction sensor comprises the following steps:

step 1: preparing an oxide layer on a substrate; then depositing, photoetching and etching polysilicon to form a heating element, a material A thermocouple arm and a contact block;

step 2: depositing an insulating layer on the basis of the step 1; then depositing, photoetching and etching metal to form a material B thermocouple arm and a contact block;

and step 3: depositing a metal on the basis of step 2; and then stripping to form the metal contact electrode.

Has the advantages that: (1) the invention realizes the wind speed and direction sensor based on the thermocouple structure, and realizes two-dimensional wind field detection by adopting the thermocouple structure. When no wind exists, the heating element generates a symmetrically distributed temperature field on the surface of the sensor, no temperature gradient exists between the two measuring ends of the thermopile, the output voltage is zero, and the heating power control circuit does not work; when wind exists, due to the fact that an asymmetric heat exchange effect exists, temperature gradients occur upstream and downstream, the thermopile generates output voltage, the heating power control circuit increases power consumption of the upstream heating element, and the downstream heating element reduces power consumption so that the upstream and downstream temperature difference is zero. The wind speed can be obtained through the power difference between the upstream heating power and the downstream heating power, and the wind direction information can be obtained through the power difference between the two orthogonal directions. Compared with thermal resistance and other temperature sensing modes, the thermocouple has no offset and drift, does not need to be applied with voltage, and has unique advantages.

(2) According to the invention, through integration of the same material in the two-dimensional thermocouple, based on a time-sharing multiplexing idea, the voltage difference of two groups of thermopiles along the x direction and the y direction is obtained in a sufficiently small period through the switch control circuit, and compared with the disclosed device structure and detection method, in the aspect of the device structure, the same material for measuring the thermopiles along the x direction and the y direction is integrated into one layer, so that the thermopiles for measuring the two-dimensional wind speed can be positioned in the center of a chip, the heating resistors are arranged in rows on the periphery, the number of the thermopiles is reduced, and the preparation process is simplified; in the aspect of a detection principle, the wind speed and direction information is measured by outputting the heating resistance power in the compensation x and y directions, the original measurement mode of respectively outputting four groups of thermopile signals is replaced, the structure of a wind speed and direction sensor device is optimized, and the detection process is optimized.

(3) The two-dimensional temperature balance mode wind speed sensor provided by the invention only needs to measure two voltages in the x and y directions, and is superior to 8 voltages needing to be measured in a comparison file.

(4) The range of the two-dimensional temperature balance mode wind speed and direction sensor provided by the invention is superior to that of a comparison file.

Drawings

FIG. 1 is a schematic structural diagram of a MEMS wind speed and direction sensor chip part of the invention;

FIG. 2 is a cross-sectional view of FIG. 1 taken along the x-direction;

FIG. 3 is a cross-sectional view taken along the y-direction of FIG. 1;

FIG. 4 is a schematic structural diagram of a thermocouple arm made of a material A at the lower layer of a chip part of the MEMS wind speed and direction sensor of the invention;

FIG. 5 is a cross-sectional view taken along aa' of FIG. 3;

FIG. 6 is a cross-sectional view along bb' of FIG. 3;

FIG. 7 is a schematic diagram of the structure of a thermocouple arm made of material B arranged on the upper layer of the chip part of the MEMS anemorumbometer sensor of the present invention;

FIG. 8 is a cross-sectional view taken along cc' of FIG. 5;

fig. 9 is a cross-sectional view taken along dd' of fig. 5.

Detailed Description

The invention is further explained below with reference to the drawings.

A two-dimensional temperature balance mode MEMS wind speed and direction sensor comprises a sensor chip part and a measurement and control circuit. The sensor chip portion includes a substrate 1, a heating element 2, a temperature measuring element, and a metal contact electrode 6. Four heating elements 2 are symmetrically distributed on the substrate 1 around the center of the chip to form a symmetrical temperature distribution field at the chip surface. The temperature measuring element is composed of a first thermopile distributed along the N-S direction and a second thermopile distributed along the W-E direction, wherein the first thermopile and the second thermopile are mutually orthogonal, the first thermopile and the second thermopile are respectively composed of a lower-layer material A thermocouple arm 3 and an upper-layer material B thermocouple arm 5, and the two material layers are insulated by an insulating layer 4. Wherein, the lower material A thermocouple arm 3 is positioned on the upper surface of the substrate 1; the insulating layer 4 is provided with a through hole for communicating the upper layer material with the lower layer material to form a two-dimensional thermopile structure, and interlayer interconnection is formed at a contact position through heavy doping, wherein the contact position is as shown in fig. 2, fig. 3 and fig. 9. Two metal contact electrodes 6 are connected to the first and second thermopiles and the four heating elements 2, respectively.

The measurement and control circuit comprises a signal amplification circuit and a heating power control circuit, the signal amplification circuit is used for amplifying output signals of the first thermopile and the second thermopile and then inputting the amplified output signals into the heating power control circuit, and the heating power control circuit is used for carrying out power control on the heating element so as to realize that the output of the two thermopiles is zero and reach a temperature balance state. Specifically, the heating power control circuit controls the on and off of one group of heating elements 2 distributed along the N-S direction and the other group of heating elements 2 distributed along the W-E direction through a time division multiplexing circuit.

When the wind speed and direction sensor works, the principle of the direction x is consistent with that of the direction y, taking the direction x as an example, the heating element 2 consumes certain power to maintain the temperature of a chip, a temperature measuring thermopile formed by a thermocouple arm 3 of a material A and a thermocouple arm 5 of a material B along the direction x senses the temperature difference of the direction x, and the generated voltage is processed by a signal amplifying circuit and then is input into a heating power control circuit for feedback regulation. Under the windless condition, no temperature gradient exists in the x direction, the output voltage of the thermopile is zero, an adder-subtractor in the heating power control circuit does not work, the power consumed by the heating element is not subjected to feedback regulation, and the heating element is heated by the same initial power; under the windy condition, assuming that the wind direction is along the positive direction of x, more heat at the upstream is taken away due to heat convection, so that the temperature at the upstream is slightly lower than that at the downstream, a temperature gradient is generated, voltage is generated on the thermopile, the amplified voltage is input to the heating power control circuit to perform feedback operation, then the heating element is controlled, and the power P of the heating element at the upstream is controlled₁Increasing the power P of the downstream heating element₂And reducing, keeping the sum of the total heating power on the upstream heating element and the downstream heating element unchanged, so that the upstream temperature is increased, the downstream temperature is reduced until dynamic balance is achieved, the output of the thermopile in the x direction is zero, and the formula shows that the power consumption on the upstream heating element and the downstream heating element is in direct proportion to the square root of the wind speed at the moment, so that the wind speed information is obtained through calculation. Based on time division multiplexingThe on-off of the circuit is controlled by the adjusting switch, and the wind speed component in the y direction is switched to be measured in a sufficiently small period, so that the wind speed and wind direction information is obtained.

A preparation method of a two-dimensional temperature balance mode MEMS wind speed and direction sensor comprises the following steps:

step 1: preparing an oxide layer on a substrate 1; depositing, photoetching and etching polysilicon to form a heating element 2, a material A thermocouple arm 3 and a contact block;

step 2: depositing an insulating layer 4 on the basis of step 1; depositing, photoetching and etching metal to form a material B, namely a thermocouple arm 5 and a contact block;

and step 3: depositing a metal on the basis of step 2; the metal contact electrode 6 is formed by stripping.

The method is based on a temperature balance mode, realizes zero temperature difference in two vertical directions by adjusting the heating power consumption in 4 directions of the south, the east and the west, and finally judges the wind speed and the wind direction according to the 4 heating power consumptions.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.