KR100829165B1 - Mems appratus for measuring acceleration in three axes - Google Patents

Abstract

A 3-axis MEMS(Micro Electro Mechanical System) acceleration sensor is provided to measure an acceleration in a space without measuring an external pressure or a temperature by compensating for a variation in a fluid pressure. First to fourth heating points(71,72,73,74), first to fourth thermal-electric pairs(30,40,50,60), and a first cavity(22) are formed on a first substrate(20). The thermal-electric pair has a thermal-electric pair junction which is contacted with the heating point to measure temperatures of the respective heating points. A fifth heating point, a fifth thermal-electric pair, and a second cavity are formed on a second substrate(120). The fifth thermal-electric pair has a thermal-electric pair junction, which is contacted with the fifth heating point. The first and second heating points are arranged to be apart from each other along a first axis line. The third and fourth heating points are arranged to be apart from each other along a second axis line, which is normal to the first axis line. The fifth and first heating points are arranged to be apart from each other along a third axis line, which is normal to the first and second substrates. A first axis acceleration is measured by using a temperature difference between the first and second heating points. A second axis acceleration is measured by using a temperature difference between the third and fourth heating points. A third axis acceleration is measured by using a temperature difference between the fifth and first heating points.

Description

3-axis MEMS acceleration sensor {MEMS appratus for measuring acceleration in three axes}

1 is a perspective view of a three-axis MEMS acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a plan view of a first substrate of the triaxial MEMS acceleration sensor of FIG. 1. FIG.

3 is a plan view of a second substrate of the triaxial MEMS acceleration sensor of FIG.

4 is a cross-sectional view taken along the line IV-IV of the first substrate of FIG. 2;

5 is a cross-sectional view taken along line V-V of the second substrate of FIG.

6 is a circuit diagram of the current supply of the three-axis MEMS acceleration sensor of FIG.

7 is a circuit diagram for voltage measurement of the 3-axis MEMS acceleration sensor of FIG.

<Description of the symbols for the main parts of the drawings>

20: first substrate 21: the first substrate body

22: first joint 30: first thermocouple

40: second thermocouple 50: third thermocouple

60: fourth thermocouple 70: first heating element

71: first heating point 72: second heating point

73: third heating point 74: fourth heating point

100: 3-axis MEMS acceleration sensor 120: second substrate

121: second substrate body 122: second cavity

130: fifth thermocouple 140: sixth thermocouple

170a, 170b: second heating element 171: fifth heating point

172: 6th heating point A1: 1st axis

A2: second axis A3: third axis

The present invention relates to a three-axis micro electro-mechanical system (MEMS) acceleration sensor, and more particularly, by using a phenomenon in which the degree of cooling of a heating element due to a tropical flow of a fluid, ie, gas or liquid, depends on the direction and magnitude of acceleration. A three-axis MEMS acceleration sensor for measuring acceleration.

Currently, acceleration sensors are typically used for airbags and suspension devices of automobiles, position control devices for aviation and military vehicles, motion input devices and shock detection devices for electronic products such as computers and mobile phones.

Conventional acceleration sensors are generally classified into servo type, piezoelectric type, piezoresistive type, and capacitance type according to the operation method. In each of these acceleration sensors, a force (F = ma) is applied to a moving structure having a certain mass (m) to accelerate the moving structure to a constant acceleration (a), and the control changes according to the displacement of the moving structure in the state. Acceleration is obtained by measuring the signal, piezovoltage, piezoresistance, and capacitance. In addition, in the conventional acceleration sensor, in order to increase the accuracy of the acceleration measurement, a structure for measuring the displacement of the moving structure that changes with the acceleration as accurately as possible should be provided. There is a problem such as weakening the durability of the acceleration sensor.

On the other hand, the convective acceleration sensor using a tropical flow phenomenon of the fluid, U.S. Patent Nos. 2,440,189, 2,455,394, 5,581,034, 6,182,509 or Japanese Patent Laid-Open No. 7-260820, Japanese Patent Laid-Open No. 2000-193677, etc. Although it can be implemented through the invention of the present invention, such a conventional convective acceleration sensor has a problem that the sensitivity and response rate is lower than the acceleration sensor using the movement structure.

In addition, in the conventional convective acceleration sensor, a biaxial acceleration sensor capable of measuring only acceleration in two axial directions crossing each other on a plane is mainstream, and acceleration in three axial directions intersecting with each other in space. Even in the case of a convective multi-axis acceleration sensor that can measure, the structure can measure the acceleration only when at least three substrates are stacked, which increases the size of the product, complicates the manufacturing process, and lowers the production yield. There is a problem that the production cost increases.

The present invention has been made to solve the above problems, and has a structure consisting of two substrates arranged in parallel, it is possible to measure the acceleration in each of the three axial directions crossing each other in space, MEMS process or 3-axis MEMS acceleration sensor with improved structure to reduce product size and simplify production process by using semiconductor micromachining technology, which can increase product yield and reduce product cost The purpose is to provide.

In order to achieve the above object, the three-axis MEMS acceleration sensor of the present invention, the three-axis MEMS acceleration sensor for measuring the acceleration in each of the first, second, and three axis direction crossing each other in space using a tropical flow of the fluid The first heating point, the second heating point, the third heating point and the fourth heating point, which generate heat by the applied current, and the respective heating points are contacted to measure the temperature of the respective heating points. A first thermocouple, a second thermocouple, a third thermocouple, and a fourth thermocouple having a thermocouple junction, and a fluid capable of passing a fluid below the first, second, third, and fourth heating points. A first substrate having one cavity; A fifth thermocouple disposed in parallel with the first substrate and having a fifth heating point generating heat by an applied current, and having a thermocouple junction point in contact with the fifth heating point to measure a temperature of the fifth heating point; And a second substrate provided with a second cavity through which the fluid moves below the fifth heating point, wherein the first heating point and the second heating point are spaced apart from each other along the first axis direction. The third heating point and the fourth heating point are disposed to be spaced apart from each other along a second axis direction crossing the first axis direction, and the fifth heating point and the first heating point are disposed on the first substrate. And spaced apart from each other along a third axis direction crossing the second substrate, using the temperature difference between the first heating point and the second heating point, the acceleration in the first axis direction, and the third heating point. By using the temperature difference between the fourth heating point The acceleration in the third axis direction is measured by using the acceleration in the second axis direction and the temperature difference between the fifth heating point and the first heating point.

In the three-axis MEMS acceleration sensor according to the present invention, preferably, the angle formed by the first axis direction and the second axis direction is a right angle, the angle formed by the third axis direction and the first axis direction, and the The angle formed by the third axis direction and the second axis direction is a right angle.

In the 3-axis MEMS acceleration sensor according to the present invention, preferably, the first heating point, the second heating point, the third heating point and the fourth heating point are located at each vertex of the conductive thin film having a rectangular band shape. While electrically connected to each other, in order to apply current to the heating points, four electrodes are provided between neighboring heating points.

In the three-axis MEMS acceleration sensor according to the present invention, preferably, in order to correct the influence of the change in the pressure of the fluid on the temperature of each heating point, any one of the first, second, three axis direction The pressure of the fluid is measured using the sum of the temperatures of two heating points spaced apart from each other along the direction.

In the three-axis MEMS acceleration sensor according to the present invention, preferably, the second substrate, the sixth heating point is spaced apart from the fifth heating point along the first axis direction and generates heat by an applied current And a sixth thermocouple having a thermocouple junction point in contact with the sixth heating point to measure the temperature of the sixth heating point, and using the sum of the temperatures of the fifth heating point and the sixth heating point. Measure the pressure of the fluid.

Hereinafter, a preferred embodiment of a three-axis MEMS acceleration sensor according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a three-axis MEMS acceleration sensor according to an embodiment of the present invention, Figure 2 is a plan view of the first substrate of the three-axis MEMS acceleration sensor of Figure 1, Figure 3 is a three-axis MEMS acceleration sensor of Figure 1 4 is a cross-sectional view taken along the line IV-IV of the first substrate of FIG. 2, FIG. 5 is a cross-sectional view taken along the V-V line of the second substrate of FIG. 3, and FIG. FIG. 7 is a circuit diagram of current supply of the MEMS acceleration sensor, and FIG. 7 is a circuit diagram of voltage measurement of the 3-axis MEMS acceleration sensor of FIG. 1.

1 to 7, the three-axis MEMS acceleration sensor 100 according to the present embodiment, the first, second, third axis (A1) (A2) ( A first substrate 20 and a second substrate 120 are provided for measuring acceleration in the direction of A3).

The first substrate 20 is for measuring the acceleration in the direction of the first and second axes A1 and A2 crossing each other on a single plane, and includes the first substrate body 21 and the first heating element ( 70, the first heating point 71, the second heating point 72, the third heating point 73 and the fourth heating point 74, the first thermocouple 30, the second thermocouple 40 And a third thermocouple 50 and a fourth thermocouple 60.

The first substrate body 21 is formed of an intermediate plate material 21a made of a semiconductor material such as silicon, and a silicon compound thin film 21b (21c) made of silicon nitride or the like deposited on the upper and lower surfaces of the intermediate plate material 21a. consist of. The silicon composite thin film 21b deposited on the upper surface of the intermediate plate 21a may include the first heating element 70, the first thermocouple 30, the second thermocouple 40, the third thermocouple 50, and the first thermocouple 50. It serves as a structure for supporting the four thermocouple 60, the silicon compound thin film 21c deposited on the lower surface of the intermediate plate (21a) serves to protect the intermediate plate (21a). The first substrate body 21 is provided with a first cavity 22 for passing a fluid flowing by tropical flow, and the first cavity 22 is formed at the center of the first substrate body 21. It is formed to penetrate the first substrate body 21.

The silicon compound thin films 21b and 21c are deposited on the upper and lower surfaces of the intermediate plate 21a through chemical vapor deposition, and planar shapes are formed through photolithography and reactive ion etching. The first cavity 22 is formed by anisotropic etching using photolithography and tetramethyl-ammonium-hydroxide solution.

The first heating element 70 is provided on the first substrate body 21. The first heating element 70 is made of a conductive material, such as nickel, chromium, and generates heat by its own resistance when a current is supplied. In the present exemplary embodiment, the first heating element 70 is a conductive thin film having a rectangular band shape, and each vertex of the first heating element 70 having the rectangular band shape has a first heating point 71 and a second heating point 72. ), The third heating point 73 and the fourth heating point 74 is located. Four electrodes 75, 76, 77, and 78 are provided for supplying current to the first heating element 70, and the electrodes 75, 76, 77, and 78 are adjacent to each other. It is disposed between the points 71, 73, 73, 72, 72, 74 and 74, 71, respectively. One end of the electrodes 75, 76, 77, 78 is electrically connected to the first heating element 70 in contact with one side of the first heating element 70, and the electrodes 75, 76. The other end of the (77) (78) is connected to the current supply device 201 capable of supplying a current through the electrodes (75) (76) (77) (78). The electrodes 75, 76, 77, and 78 are formed of a thin film of a metallic material having a low resistance such as gold (Au) in order to minimize heat generation and electrical noise of the electrodes. The first heating element 70 and the electrodes 75, 76, 77, 78 are deposited by electron beam deposition or sputtering, and are wet using photolithography, a lift-off method, or an etching solution. Through etching, a planar shape is formed.

When the current is supplied from the current supply device 201, Joule heat is generated in the first heating element 70, so that the first, second, third, and third points corresponding to the vertices of the first heating element 70 are generated. The temperature of the four heating points 71, 72, 73 and 74 is higher than the ambient fluid temperature.

As shown in FIG. 6, current flows from the current supply device 201 to the first heating element 70 through the electrodes 75 and 76, and the current flows through the electrodes 77 and 78. Return to feeder 201. At this time, the magnitude of the current supplied from the current supply device 201 is set to i, the current of i / 4 flows to the first heating element 70 by Kirchhoff's law.

The first heating point 71 and the second heating point 72 are spaced apart from each other along the direction of the first axis A1 and used to measure the acceleration in the direction of the first axis A1. . In addition, the third heating point 73 and the fourth heating point 74 are disposed to be spaced apart from each other along the direction of the second axis A2, and to measure the acceleration in the direction of the second axis A2. Is used. The first axis A1 and the second axis A2 intersect each other to meet at one point without being coincident with each other on the plane formed by the first substrate 20. In the present embodiment, the angle formed between the direction of the first axis A1 and the direction of the second axis A2 is a right angle, and an imaginary connecting the first heating point 71 and the second heating point 72. The distances from the center point 23 where the line and the imaginary line connecting the third heating point 73 and the fourth heating point 74 meet each other are the same as each heating point 71, 72, 73, 74. . Accordingly, the first heating point 71, the second heating point 72, the third heating point 73, and the fourth heating point 74 are disposed in a point symmetrical form with respect to the center point 23. .

The first, second, third, and fourth thermocouples 30, 40, 50, and 60 measure temperatures of the first, second, third, and fourth heating points 71, 72, 73, and 74. For measurement, the first conductive lines 31, 41, 51, 61, the second conductive lines 32, 42, 52, 62, and the thermocouple junction points 33, 43 ( 53 and 63. The first conductive lines 31, 41, 51, 61, and the second conductive lines 32, 42, 52, 62 are each formed of a thin film of a metal material such as nickel and chromium. The first conductive lines 31, 41, 51, 61 and the second conductive lines 32, 42, 52, 62 are made of different metals, for example, the first conductive line. When the (31) (41) (51) (61) is made of nickel, the second conductive lines (32) (42) (52) (62) are made of metal other than nickel, such as chromium. The thermocouple junction points 33, 43, 53, and 63 are the first conductive lines 31, 41, 51, 61, and the second conductive lines 32, 42, 52, 62. The ends of the are formed electrically connected to each other. The thermocouple junctions 33, 43, 53, and 63 form the first, second, third, and fourth heating points 71, 72, 73, 74, and an insulator thin film 24 such as silicon oxide. Touch each other in between. Electrode pads 36, 37, 46, 47, 56, 57, 66, 67 at both ends of the first, second, third, and fourth thermocouples 30, 40, 50, 60, respectively. This is provided. An amplifier 211 is connected to the electrode pad 37 of the first thermocouple and the electrode pad 47 of the second thermocouple, and the voltage amplified by the amplifier 211 is a voltage measuring device (not shown). Is measured by. In addition, an amplifier 212 is connected to the electrode pad 56 of the third thermocouple and the electrode pad 66 of the fourth thermocouple, and the voltage amplified by the amplifier 212 is a voltage measuring device (not shown). Is measured by

The insulator thin film 24 is deposited through chemical vapor deposition, and has a planar shape through photolithography and reactive ion etching. The first conductive lines 31, 41, 51, 61, the second conductive lines 32, 42, 52, 62, and electrode pads 36, 37, 46, 47, 56, 57) 66 and 67 are deposited by electron beam deposition or sputtering, and are formed in planar form through photolithography, lift-off method or wet etching using an etching solution.

The second substrate 120 is disposed in parallel with the first substrate 20 to measure the acceleration in the direction of the third axis A3 that intersects the plane formed by the first substrate 20. The second substrate main body 121, the second heating element 170a and 170b, the fifth heating point 171 and the sixth heating point 172, the fifth thermocouple 130 and the sixth thermocouple ( 140). In the present embodiment, the second substrate 120 is disposed below the first substrate 20.

The second substrate main body 121 is composed of an intermediate plate material 121a of a semiconductor material such as silicon and a silicon compound thin film 121b such as silicon nitride deposited on the upper surface of the intermediate plate material 121a. The silicon compound thin film 121b serves as a structure for supporting the second heating elements 170a and 170b, the fifth thermocouple 130, and the sixth thermocouple 140. The second substrate body 121 is provided with a second cavity 122 in the center of the second substrate body 121 for allowing the fluid flowing by the tropical flow.

The silicon compound thin film 121b is deposited on the upper surface of the intermediate plate 121a through chemical vapor deposition, and a planar shape is formed through photolithography and reactive ion etching. The second cavity 122 is formed through an isotropic etching method using photolithography and non-fluorinated non-gas.

The second heating elements 170a and 170b are provided on the second substrate main body 121. Like the first heating element 70, the second heating elements 170a and 170b are also made of a conductive material such as nickel and chromium, thereby generating heat by self resistance. In the present exemplary embodiment, the second heating elements 170a and 170b are conductive thin films having an “a” shape, and a pair of second heating elements 170a and 170b face each other. Is placed. The fifth heating point 171 and the sixth heating point 172 are positioned at each vertex portion of the second heating elements 170a and 170b of the “a” shape. The fifth heating point 171 and the sixth heating point 172 are positioned below each of the first heating point 71 and the second heating point 72. Four electrodes 175, 176, 177, and 178 for supplying current to the second heating elements 170a and 170b are provided. One end of the electrodes 175, 176, 177, and 178 is in contact with the second heating elements 170a and 170b to be electrically connected to the second heating elements 170a and 170b and the electrode 175. The other end of 176, 177, 178 is connected to a current supply device 202 capable of supplying current through its electrodes 175, 176, 177, 178. The electrodes 175, 176, 177, and 178 are formed of a thin film of a metallic material having a low resistance such as gold (Au) to minimize heat generation and electrical noise of the electrodes. The second heating elements 170a, 170b and the electrodes 175, 176, 177, and 178 are deposited by electron beam deposition or sputtering, and wet etching using a photolithography, a lift-off method or an etching solution. Through the planar shape is formed.

As shown in FIG. 6, current flows from the current supply device 202 to the pair of second heating elements 170a and 170b through the electrodes 175 and 176, and the electrodes 177 and 178. The current returns to the current supply device 202 from the pair of second heating elements 170a and 170b. At this time, the magnitude of the current supplied from the current supply device 202 connected to the second substrate 120 is set to i / 2, and the pair of second heating elements 170a and 170b is in accordance with Kirchhoff's law. Like the first heating element 70, i / 4 current flows respectively. Equalizing the amount of current supplied to each of the heating elements 70, 170a, and 170b equals the amount of heat generated at each of the heating points 71, 72, 73, 74, 171, and 172. To make it work.

The fifth heating point 171 and the first heating point 71 are spaced apart from each other along the direction of the third axis A3 and used to measure the acceleration in the direction of the third axis A3. . The sixth heating point 172 and the fifth heating point 171 may be disposed to be spaced apart from each other along the direction of the first axis A1 or the direction of the second axis A2, but in this embodiment, It is arranged to be spaced apart from each other along the axis A1 direction. The third axis A3 intersects and meets the plane formed by the first substrate 20 and the plane formed by the second substrate 120 at one point. In the present embodiment, the angle formed by the direction of the third axis A3 and the direction of the first axis A1 is a right angle, and the angle formed by the direction of the third axis A3 and the direction of the second axis A2 is also perpendicular. to be.

The second and second substrates 120 are provided with fifth and sixth thermocouples 130 and 140 for measuring temperatures of the fifth and sixth heating points 171 and 172. The fifth and sixth thermocouples 130 and 140 may be formed of the same material and structure as the first, second, third and fourth thermocouples 30, 40, 50, and 60 provided on the first substrate 20. The thermocouple junction 133 of the fifth thermocouple may include the fifth heating point 171, and the thermocouple junction point 143 of the sixth thermocouple may include the sixth heating point 172 and an insulator thin film such as silicon oxide. 124 is in contact with each other. Electrode pads 136 and 137 and 146 and 147 are provided at both ends of the fifth and sixth thermocouples 130 and 140, respectively. An amplifier 213 is connected to the electrode pad 137 of the fifth thermocouple and the electrode pad 37 of the first thermocouple, and the voltage amplified by the amplifier 213 is transferred to a voltage measuring device (not shown). Is measured.

The insulator thin film 124 is deposited through chemical vapor deposition, and a planar shape is formed through photolithography and reactive ion etching. The first conductive lines 131, 141 and the second conductive lines 132, 142 and the electrode pads 136, 137, 146, 147 forming the fifth and sixth thermocouples 130, 140 are formed by electron beam deposition or sputtering. It is deposited by a method, and a planar shape is formed through photolithography, a lift-off method or wet etching using an etching solution.

In order to correct the effect of the change in the pressure of the fluid on the temperature of the first, second, third, fourth, fifth, sixth heating point 71, 72, 73, 74, 171, 172, The pressure of the fluid is measured using the sum of the temperatures of two heating points spaced apart from each other along one of the first, second and third axes A1, A2, and A3. That is, the sum of the temperatures of the first heating point 71 and the second heating point 72 disposed to be spaced apart from each other along the direction of the first axis A1 or spaced apart from each other along the direction of the second axis A2. The sum of the temperatures of the arranged third heating point 73 and the fourth heating point 74 or the fifth heating point 171 and the first heating point disposed to be spaced apart from each other along the direction of the third axis A3 ( The pressure of the fluid using either the sum of the temperatures of 71 or the sum of the temperatures of the fifth heating point 171 and the sixth heating point 172 spaced apart from each other along the direction of the first axis A1. In this embodiment, the pressure of the fluid is measured using the sum of the temperatures of the fifth heating point 171 and the sixth heating point 172. An amplifier 214 is provided on the electrode pad 137 of the fifth thermocouple 130 in contact with the fifth heating point 171 and the electrode pad 146 of the sixth thermocouple 140 in contact with the sixth heating point 172. ) Is connected, and the voltage amplified by the amplifier 214 is measured by the voltage measuring device.

Hereinafter, the operating principle of the three-axis MEMS acceleration sensor of the present embodiment configured as described above will be described schematically with reference to FIGS. 1 to 7. The principle of measuring the acceleration in the direction of the first axis among the first, second, and third axes perpendicular to the space will be described as an example.

When a current is applied from the current supply device 201 to the first heating element 70, Joule heat is generated around the first heating element 70 so that the temperature of the fluid around the first heating element 70 increases. do. The first heating element 70 may be partitioned into and out of the first heating element 70 by a rectangular band shape of the first heating element 70, and the inside of the first heating element 70 by the joule heat of the first heating element 70. The temperature of the fluid located at is higher than the temperature located outside the first heating element (70).

Therefore, when the acceleration acts in any one direction of the first axis A1 to the three-axis MEMS acceleration sensor 100, the first heating point 71 and the second heating point 72 is the The degree of cooling by the fluid flow in the direction of the first axis A1 is different. For example, when the acceleration acts on the three-axis MEMS acceleration sensor 100 in the direction "+ A1" which is one of the directions of the first axis A1, the first heating point 71 and Acceleration in the "-A1" direction, which is the other direction of the first axis A1, acts on the fluid around the second heating point 72. By the flow of the fluid in the "-A1" direction, the second heating point 72 is cooled by the fluid located inside the first heating element 70 having a temperature higher than the average temperature of the entire fluid, The first heating point 71 is cooled by a fluid located outside the first heating element 70 having a temperature lower than the average temperature of the entire fluid. Therefore, the temperature of the second heating point 72 is higher than the temperature of the first heating point 71. On the contrary, when the acceleration acts on the 3-axis MEMS acceleration sensor 100 in the "-A1" direction, the temperature of the first heating point 71 becomes higher than the temperature of the second heating point 72.

As such, the degree of cooling of the first heating point 71 and the second heating point 72 is different due to a tropical flow phenomenon of a fluid having a different temperature, and the temperature difference is the first heating point 71. ) Is output as a difference between the voltage output from the first thermocouple 30 in contact with the voltage and the voltage output from the second thermocouple 40 in contact with the second heating point 72. Since the first thermocouple 30 and the second thermocouple 40 are differentially connected, the voltage V1 amplified by the amplifier 211 becomes a value proportional to the acceleration in the direction of the first axis A1. By measuring the temperature difference between the first heating point 71 and the second heating point 72 as described above, the direction (positive and negative direction) and magnitude of the acceleration acting in the direction of the first axis A1 can be obtained. do.

In the same principle as above, the difference between the output voltages of the third thermocouple 50 and the fourth thermocouple 60 generated by the temperature difference between the third heating point 73 and the fourth heating point 74 is the amplifier 212. Is amplified, and the amplified voltage V2 becomes a value proportional to the acceleration in the direction of the second axis A2. The difference between the output voltages of the fifth thermocouple 130 and the first thermocouple 30 generated by the temperature difference between the fifth heating point 171 and the first heating point 71 is amplified by the amplifier 213. The amplified voltage V3 becomes a value proportional to the acceleration in the direction of the third axis A3.

On the other hand, as the pressure of the fluid to be changed is the degree of cooling of the heating point is different. In general, as the pressure of the fluid increases, the flow of tropical air is more likely to increase, and the degree of cooling of the heating point is increased. Therefore, hereinafter, the principle of accurately calculating the magnitude of the acceleration by measuring the temperature of the heating point when the pressure of the fluid changes will be described.

The fifth heating point 171 and the sixth heating point 172 receive cooling effects opposite to each other when the acceleration in the "+ A1" direction or the acceleration in the "-A1" direction acts. Therefore, the sum of the temperatures of the fifth heating point 171 and the sixth heating point 172 is always constant regardless of the direction of acceleration. However, the sum of the temperatures of the fifth heating point 171 and the sixth heating point 172 depends only on the pressure of the entire fluid. That is, when the pressure of the fluid is high, the sum of the temperatures of the fifth heating point 171 and the sixth heating point 172 becomes low, and when the pressure of the fluid is low, the fifth heating point 171 and The sum of the temperatures of the sixth heating point 172 becomes high. The electrode pad 137 of the fifth thermocouple and the electrode pad 146 of the sixth thermocouple are connected to the amplifier 214 in the form of a thermopile such that an output voltage thereof is added thereto. The amplified voltage Vp becomes a value proportional to the pressure. Therefore, the pressure of the fluid can be obtained from the sum of the temperatures of the fifth heating point 171 and the sixth heating point 172, and the pressure of the first heating point 71 and the second heating point 72 is obtained using the same. By correcting the change in the pressure of the fluid at the temperature difference, it is possible to accurately calculate the magnitude of the acceleration in the direction of the first axis A1 even when the pressure of the fluid changes.

In the acceleration sensor, the principle of measuring the temperature to obtain the acceleration and correcting the change in pressure is well known as disclosed in Korean Patent Laid-Open No. 2006-0049572, and so the detailed description thereof will be omitted.

Using the three-axis MEMS acceleration sensor according to the present embodiment configured as described above, it has an acceleration sensor having a structure in which two substrates are arranged in parallel with respect to each of the first, second and third axis directions crossing each other in space. Acceleration can be measured, which makes it possible to miniaturize acceleration sensor products by using MEMS process or semiconductor micromachining technology, and simplify the manufacturing process of acceleration sensor products. Therefore, it is possible to increase the production yield of the product and at the same time can reduce the production cost.

In addition, when using the three-axis MEMS acceleration sensor according to the present embodiment configured as described above, the function of measuring the pressure of the fluid irrespective of the acceleration is implemented in the three-axis MEMS acceleration sensor itself, so that the pressure change of the fluid By compensating the influence on the acceleration, it is possible to obtain the effect of more accurately measuring the acceleration in each of the first, second, and three axis directions crossing each other in space.

Although preferred embodiments and modifications have been described above, the three-axis MEMS acceleration sensor according to the present invention is not limited to the above-described examples, and within the scope not departing from the technical spirit of the present invention by modifications or combinations thereof. Various types of three-axis MEMS acceleration sensors can be embodied in the art.

The three-axis MEMS acceleration sensor according to the present invention has an acceleration sensor composed of two substrate structures arranged in parallel to measure acceleration in three axial directions crossing each other in space, thereby utilizing a MEMS process or semiconductor micromachining technology. The product can be manufactured in a small size, and the production cost can be reduced along with an increase in the production yield of the product.

In addition, the three-axis MEMS acceleration sensor according to the present invention has the effect of correcting the change in the fluid pressure in itself, it is possible to measure the acceleration in space more accurately without the need to measure the external pressure or temperature separately There is.

Claims (5)

In a three-axis MEMS acceleration sensor for measuring the acceleration in each of the first, second, and three axis directions intersecting each other in space using a tropical flow of fluid, The first heating point, the second heating point, the third heating point and the fourth heating point that generate heat by the applied current, and the thermocouple junctions which contact each of the heating points in order to measure the temperature of the respective heating points The branch has a first thermocouple, a second thermocouple, a third thermocouple and a fourth thermocouple, and a first cavity for allowing fluid to pass through the first, second, third, and fourth heating points. A first substrate provided; A fifth thermocouple disposed in parallel with the first substrate and having a fifth heating point generating heat by an applied current, and having a thermocouple junction point in contact with the fifth heating point to measure a temperature of the fifth heating point; And a second substrate provided with a second cavity through which the fluid moves below the fifth heating point. The first heating point and the second heating point are disposed to be spaced apart from each other along the first axis line direction, and the third heating point and the fourth heating point point in a second axis direction crossing the first axis line direction. The first heating point and the fifth heating point are spaced apart from each other along the third axis direction intersecting the first substrate and the second substrate, Acceleration in the direction of the first axis using the temperature difference between the first and second heating points, acceleration in the direction of the second axis using the temperature difference between the third and fourth heating points and the The acceleration in the third axis direction by measuring the temperature difference between the fifth heating point and the first heating point, the three-axis MEMS acceleration sensor. The method of claim 1, The angle formed between the first axis direction and the second axis direction is a right angle, And an angle formed by the third axis direction and the first axis direction and an angle formed by the third axis direction and the second axis direction are perpendicular to each other. The method of claim 1, The first heating point, the second heating point, the third heating point, and the fourth heating point are electrically connected to each other while being located at each vertex of the conductive thin film having a rectangular band shape. In order to apply current to the heating points, three-axis MEMS acceleration sensor, characterized in that the four electrodes are provided between the adjacent heating points. The method of claim 1, In order to correct the effect of the change in pressure of the fluid on the temperature of each heating point, 3. The 3-axis MEMS acceleration sensor of claim 1, wherein the pressure of the fluid is measured using a sum of temperatures of two heating points spaced apart from each other along one of the first, second, and three axis directions. The method of claim 4, wherein The sixth heating point in the second substrate is spaced apart from the fifth heating point along the first axis direction and generates heat by an applied current, and the sixth heating point for measuring the temperature of the sixth heating point. A sixth thermocouple having a thermocouple junction in contact with the heating point is provided, And measuring the pressure of the fluid using the sum of the temperatures of the fifth heating point and the sixth heating point.

Images