KR100461787B1 - Accelerometers using mems technology and method for manufacturing the same - Google Patents

Abstract

The present invention relates to an acceleration sensor using MEMS technology and a method of manufacturing the same.

The manufacturing method of the present invention comprises the steps of forming a first oxide film on both sides of the silicon wafer; Patterning the first oxide film; Bulk etching a bottom surface of the patterned silicon wafer; Forming a second oxide film on the bulk etched silicon wafer; Patterning the second oxide film; Stacking a base silicon wafer on a bottom surface of the silicon wafer; Forming a vibration sensor on the silicon wafer by DEEP RIE (Reactive Ion Etching) etching; Forming an optical fiber insertion groove on the silicon wafer by DEEP RIE (Reactive Ion Etching) etching; Fixing an input and an output optical fiber to the optical fiber insertion groove; Packaging a fixture on an upper surface of the silicon wafer on which the input and output optical fibers are fixed; It is characterized by including. Therefore, it is possible to make a small sensor by using MEMS (Micro Electro Mechanical System) process, and it is possible to efficiently diagnose and monitor a large number of machine tools at a long distance when constructing an unmanned automation system using optical fiber as a light transmission path. have.

Description

Accelerometer using MEMS technology and its manufacturing method {ACCELEROMETERS USING MEMS TECHNOLOGY AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to an acceleration sensor for detecting acceleration and a method of manufacturing the same, and more particularly, to an acceleration sensor using MEMS (Micro Electro Mechanical System) technology that enables efficient diagnosis and monitoring of a plurality of machine tools in an unmanned automated system. It relates to a manufacturing method.

Accelerometer is a kind of inertial sensor, and its application field is expanding according to the demand for improving performance of automobiles and home appliances and adding new functions in addition to special purpose markets such as research and military use.

Currently, the most widely used acceleration sensor is a piezoelectric acceleration sensor using a piezoelectric element, which uses a principle in which electric charges are generated on both sides when a force is applied to the piezoelectric element in a polar direction. This potential difference is proportional to the magnitude of the applied force, so that an accurate amount of vibration can be measured. The piezoelectric acceleration sensor has a good linearity in a wider frequency range than other vibration measuring transducers, and does not require a power supply.

1 is a schematic structural diagram of a conventional piezoelectric acceleration sensor.

The base 1 which forms a square plate shape, and the vibration sensor 3 inside the space part 2 of the base 1 are provided. The vibration sensor 3 has a ketilever beam 4 that acts as a spring on one side.

The vibration sensor 3 uses electric polarization against stress of piezoelectric material such as ZnO.

When the vibration sensor 3 moves up and down by acceleration, a relative displacement of the vibration sensor 3 occurs due to an inertial force, and the displacement is detected as an electrical signal.

However, all the piezoelectric materials of these piezoelectric acceleration sensors are sensitive to temperature, so changes in ambient temperature cause changes in the sensitivity of the accelerometers. Piezoelectric acceleration sensors have high impedance, so that ground loops and triboelectric noise in connecting cables , Electromagnetic noise, etc. In addition, the conventional acceleration sensor has a problem of complex process and linearity.

The present invention is to solve the conventional problems as described above, it is possible to overcome the effects of temperature and noise in the cable and remote measurement by the use of optical fiber, and miniaturized sensor using MEMS (Micro Electro Mechanical System) technology It is an object of the present invention to provide an acceleration sensor and a method of manufacturing the same using MEMS technology that can be produced at low cost.

In order to achieve the above object, the present invention provides a method of manufacturing an acceleration sensor using a MEMS (Micro Electro Mechanical System) technology; Forming a first oxide film on both sides of the silicon wafer; Patterning the first oxide film; Bulk etching a bottom surface of the patterned silicon wafer; Forming a second oxide film on the bulk etched silicon wafer; Patterning the second oxide film; Stacking a base silicon wafer on a bottom surface of the silicon wafer; Forming a vibration sensor on the silicon wafer by DEEP Reactive Ion Etching (DRIE) etching; Forming an optical fiber insertion groove in the silicon wafer by deep reactive ion etching etching; Fixing an input and an output optical fiber to the optical fiber insertion groove; Packaging a fixture on an upper surface of the silicon wafer on which the input and output optical fibers are fixed; It provides a method of manufacturing an acceleration sensor using a MEMS technology comprising.

In addition, the present invention in the acceleration sensor using the MEMS (Micro Electro Mechanical System) technology; A silicon wafer stacked on top of the base silicon wafer; A rectangular space portion in the center and an insertion groove formed in an orthogonal direction of the space portion at a center by a DEEP Reactive Ion Etching (DRIE) etching process on the silicon wafer; A vibration sensor installed inside the space portion of the silicon wafer, the vibration sensor having a plurality of silicon beams in a vertical direction on both symmetric side surfaces, and a shutter branched on one side; An input and an output optical fiber installed in the insertion groove to measure a change of the vibration sensor; A fixture installed on the silicon wafer to fix the input and output optical fibers and the vibration sensor; It provides an acceleration sensor, characterized in that made.

1 is a perspective view schematically showing a conventional acceleration sensor,

2 is a process chart of a method of manufacturing an acceleration sensor using MEMS technology according to the present invention,

3 is a perspective view of an acceleration sensor using a MEMS technology manufactured according to the present invention,

Figure 4 is a state diagram of the shutter causing a change in the amount of light in the acceleration sensor using the MEMS technology manufactured according to the present invention.

<Description of the code | symbol about the principal part of drawing>

10: silicon wafer 10 ': base silicon wafer

11, 12: 1st, 2nd oxide film 13: Photoresistor

14: Bulk Etching

15: DEEP Reactive Ion Etching (DRIE)

20: acceleration sensor 24: space part

26: insertion groove 30: vibration sensor

32: silicon beam 34: shutter

40: input fiber 42: output fiber

44: core 50: fixture

52: border surface 54: stator

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a process diagram of a method of manufacturing an acceleration sensor using the MEMS technology according to the present invention, Figure 3 is a perspective view of the acceleration sensor using the MEMS technology manufactured according to the present invention, Figure 4 is a MEMS technology manufactured according to the present invention In the acceleration sensor using the state of the shutter that causes a change in the amount of light. The manufacturing method of the acceleration sensor using the acceleration sensor and MEMS technology according to the present invention is shown in FIG.

The acceleration sensor 20 using a semiconductor process technology on a silicon substrate using a micro electro mechanical system (MEMS), that is, a micro electromechanical system, first forms a first oxide film 11 (Si ₂ O) on both sides of the silicon wafer 10. After applying the photoresist 13 on the first oxide film 11, a part of the first oxide film 11 is removed by an exposure and patterning process.

Bulk etching (14: bulk etching) is performed on the lower surface of the patterned silicon wafer 10 using a TetraMethyl-Ammonium Hydroxide (TMAH) solution.

A second oxide film 12 is formed on both sides of the bulk etched silicon wafer 10.

The photoresist 13 is again coated on the upper surface of the silicon wafer 10 on which the second oxide film 12 is formed and patterned.

The base silicon wafer 10 'having the oxide film 11' formed only on the bottom surface of the silicon wafer 10 is laminated.

The vibration sensor 30 is formed on the silicon wafer 10 positioned on the upper side by deep reactive ion etching (DRIE) etching.

Then, the optical fiber insertion groove 26 is formed in the silicon wafer 10 by deep reactive ion etching 15 etching.

The input and output optical fibers 40 and 42 are inserted into the insertion grooves 26.

The input and output optical fibers 40, 42 are fixed to the fixture 50, and then packaged.

Referring to FIG. 3 with respect to the accelerometer manufactured as described above, the accelerometer 20 is installed on the base silicon wafer 10 ′, the silicon wafer 10 stacked thereon, and the inside of the silicon wafer 10. It is composed of a large vibration sensor 30, the input and output optical fibers 40, 42, and the fixture 50.

Here, an insertion groove 26 is formed in a direction perpendicular to the space portion 24 so that the rectangular space portion 24 and the input / output optical fibers 40 and 42 can be inserted in the center of the silicon wafer 10. .

The vibration sensor 30 installed inside the space 24 has a symmetrical structure, and two pairs of silicon beams 32 are installed at both sides. The silicon beam 32 is installed in a vertical plane such as the thickness of the vibration sensor 30. A branched shutter 34 is formed on one side of the vibration sensor 30. The vibration sensor 30 is designed to have a resonance frequency of 15 kHz to include 5 kHz, which is the vibration range of the machine tool.

In addition, the optical fiber is composed of an input optical fiber 40 from which laser light is emitted, and an output optical fiber 42 having a photo detector (not shown) connected to the end and measuring a changed amount of light. The core 44 having a thickness of 9 µm was used so that the change in the amount of light was large even in the fine displacement of the shutter 34.

One end of the input and output optical fibers 40 and 42 is inserted into the insertion groove 26 of the silicon wafer 10 in the longitudinal direction so as to face each other with the shutter 34 interposed therebetween.

A fixture 50 is installed on the silicon wafer 10 to protect the input and output optical fibers 40 and 42 and the vibration sensor 30. The fixture 50 is manufactured by a micro stereolithography technique, has a slightly larger area than the space portion 24 of the silicon wafer 10, and has an edge 52 protruding downward, and the silicon wafer 10 Coupling with) is fixed by using a separate adhesive. In addition, a stator 54 for fixing the input and output optical fibers 40 and 42 is protruded to a portion formed by bending inwardly of the edge surface 52.

Operation of the acceleration sensor 20 designed to include a vibration range of 5kHz of the machine tool according to the present invention configured as described above is as follows.

Vibration generated in the machine tool, etc. to move the vibration sensor 30 is a microstructure. At this time, the silicon beam 32 of the spring function formed in a vertical shape moves horizontally to prevent the vibration sensor 30 from vibrating in the vertical direction.

The vibration sensor 30 vibrating horizontally generates a displacement of the shutter 34.

Referring to FIG. 4, the shutter 34 positioned between the input and output optical fibers 40 and 42 is aligned with the center of the core 44. When the shutter 34 is moved by the vibration above, the displacement of the shutter 34 is generated by δy. When no vibration is applied, the end of the shutter 34 is located at the centerline of the core 44 of the input optical fiber 40, so that the amount of laser light transmitted is reduced by 1/2 so that the photodetector of the output optical fiber 42 is measured. do.

As the vibration is applied from the outside, the displacement of the shutter 34 increases, so that the amount of light transmitted becomes smaller. Therefore, since the displacement of the shutter 34 according to the external acceleration magnitude can be known in theory, the magnitude of acceleration applied to the displacement of the shutter 34 can be known by measuring the change in the amount of light according to the displacement.

The input and output optical fibers 40 and 42 used therein do not generate electrical noise generated in the conventional cable, and the amount of light passing through the optical fiber is irrelevant to the influence of temperature or magnetic field, and thus can be detected even in a poor working environment. . In addition, since the amount of light transmitted to the optical fiber is very small, the transmission loss with distance is very small.

Although the present invention has been illustrated and described with respect to certain preferred embodiments, the present invention is not limited to the above-described embodiments, and a person skilled in the art to which the present invention pertains has the present invention set forth in the claims below. Various modifications may be made without departing from the spirit of the invention.

As described above, according to the present invention, the acceleration sensor and its manufacturing method using MEMS technology can be manufactured in a small size by using MEMS (Micro Electro Mechanical System) technology, and unmanned automation using optical fiber as a light transmission path. When building a system, it is possible to efficiently diagnose and monitor a large number of machine tools over a long distance.

Claims (6)

In the manufacturing method of the acceleration sensor using the MEMS (Micro Electro Mechanical System) technology; Forming a first oxide film on both sides of the silicon wafer; Patterning the first oxide film; Bulk etching a bottom surface of the patterned silicon wafer; Forming a second oxide film on the bulk etched silicon wafer; Patterning the second oxide film; Stacking a base silicon wafer on a bottom surface of the silicon wafer; Forming a vibration sensor on the silicon wafer by Deep Reactive Ion Etching (DRIE) etching; Forming an optical fiber insertion groove in the silicon wafer by deep reactive ion etching etching; Fixing an input and an output optical fiber to the optical fiber insertion groove; Packaging a fixture on an upper surface of the silicon wafer on which the input and output optical fibers are fixed; Method of manufacturing an acceleration sensor using a MEMS technology comprising a. An acceleration sensor using MEMS (Micro Electro Mechanical System) technology; A silicon wafer stacked on top of the base silicon wafer; A rectangular space portion in the center and an insertion groove formed in an orthogonal direction of the space portion at a center thereof by a deep reactive ion etching (DRIE) etching process on the silicon wafer; A vibration sensor installed inside the space portion of the silicon wafer, the vibration sensor having a plurality of silicon beams in a vertical direction on both symmetric side surfaces, and a shutter branched on one side; An input and an output optical fiber installed in the insertion groove to measure a change of the vibration sensor; A fixture installed on the silicon wafer to fix the input and output optical fibers and the vibration sensor; Accelerometer, characterized in that made. The method of claim 2; The silicon beam, the acceleration sensor, characterized in that the vertical thickness is formed to be the same as the thickness of the vibration sensor so that displacement in the other direction by the moment. The method of claim 2; The input and output optical fiber is an acceleration sensor, characterized in that formed in the core diameter of 9㎛. The method of claim 2; The fixture, the acceleration sensor, characterized in that the stator is formed on the edge for fixing the input and output optical fiber. The method of claim 2; Acceleration sensor characterized in that the resonance frequency of the vibration sensor designed to 15kHz.