KR20060052448A - Rotation sensing apparatus and method for manufacturing the same - Google Patents

Abstract

The present invention discloses a rotation sensing device and a method of manufacturing the same. The rotation sensing device includes at least one pair of vibrators and a sensing electrode. The pair of vibrators are disposed symmetrically on the substrate, each vibrator comprising an electrostatic vibrator, a support element, and an elastic element. The support element is connected to the substrate. The elastic element is connected with the electrostatic vibrator and is firmly connected to the support element such that the electrostatic vibrator floats from the substrate to a predetermined height. The sensing electrodes disposed on the substrate correspond to at least one pair of vibrators. The vibrator may vibrate horizontally by electrostatic force, and if rotation occurs, will vibrate perpendicularly to the substrate by Coriolis force. Rotation can be measured by detecting a change in capacitance between the electrostatic vibrator and the sensing electrode. On the other hand, the method of manufacturing the rotation sensing device adopts an optical mask for manufacturing the vibration structure, so as to avoid the asymmetrical structure caused by the misalignment caused by the multiple optical masks in the manufacturing.

Rotary sensing device, vibrator, sensing electrode, substrate, electrostatic vibrator, support element, elastic element, optical mask

Description

ROTATION SENSING APPARATUS AND METHOD FOR MANUFACTURING THE SAME}

1 is a schematic view showing a preferred embodiment of a rotation sensing device according to the present invention.

2 is a structural diagram of a vibrator of a preferred embodiment of a rotation sensing device according to the present invention.

3A-3H are flow diagrams illustrating a preferred embodiment of a method for manufacturing a rotation sensing device without an electrically conductive plate.

4A-4I are flowcharts showing a preferred embodiment of a method for manufacturing the rotation sensing device of the present invention.

Fig. 5A is a schematic diagram showing the operation of the preferred embodiment of the rotation sensing device according to the present invention.

5B is a Coriolis force distribution diagram of a pair of first vibrators in accordance with a preferred embodiment while rotating about the x-axis.

Figure 6 is a schematic diagram showing another preferred embodiment of the rotation sensing device according to the present invention.

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

2: rotation detection device

20: substrate

21a, 21b: first vibrator

22a, 22b: second vibrator

23: sensing electrode

211: electrostatic vibrating body

212 support element

213: Elastic Element

[Document 1] US Patent No. 4,381,672

[Document 2] United States Patent No. 5,445,025

[Document 3] United States Patent No. 6,201,341

The present invention relates to a rotation sensing device and a method of manufacturing the same. In particular, it relates to a rotation sensing device having a symmetrical vibration structure in which only one optical mask staff needs to be manufactured. The rotation sensing device having a stable center of mass is driven to generate driving vibrations. According to the principle of Coriolis force, the rotation sensing device can generate vibration perpendicular to the axis of rotation and the drive vibration when the rotation can be measured.

The gyroscope is an inertial sensing element that measures the rotational angular velocity mainly by the law of inertia. A typical gyroscope uses the laws of conservation of momentum and is applied to navigation in the military, aviation and navigation fields. However, typical gyroscopes are complex in structure, quickly worn and ruptured, short in life, expensive and heavy.

With the development of the consumer industry, the demand for light, low cost and long life gyroscopes is increasing in the fields of inertial navigation, automotive, robotics, medical engineering, consumer electronics and electronic entertainment. Due to recent advances in semiconductor technology, microelectromechanical system (MEMS) process technology combined with semiconductor technology, mechanical and electronic technology has been further developed. Thus, by MEMS technology, a light and inexpensive micro gyroscope can be manufactured.

In gyroscope sensors, vibration sensors for sensing rotation are the mainstream, and have been disclosed in a number of prior arts. For example, the technique disclosed in US Pat. No. 4,381,672 uses a single cantilever beam structure to sense rotation. However, the center of mass of the cantilever structure changes continuously due to the vibration of the cantilever beam, and noise occurs to disturb the measurement result. Accordingly, US Pat. Nos. 5,445,025 and 6,201,341 use symmetrical vibration structures to overcome the disadvantage of changing the center of mass. However, the structure disclosed in the above-mentioned two patents is difficult to miniaturize by the MEMS process technology, although the problem of changing the center of mass due to the asymmetrical structure can be solved.

In view of the above-mentioned problems, an improved rotation sensing device and its manufacturing method are required to solve the drawbacks of the prior art.

It is a main object of the present invention to provide a rotation sensing device and a method of manufacturing the same, which have a stable center of mass and are driven to generate driving vibrations. According to the principle of Coriolis force, in order to measure rotation when rotation occurs, the rotation sensing device generates vibration perpendicular to the axis of rotation and the drive vibration.

It is a second object of the present invention to provide a rotation sensing device and a method of manufacturing the same, which can be manufactured by MEMS process technology. The present invention utilizes a symmetrical structural combination to generate a resonance effect to reduce the power consumption of the element and to reduce the electrostatic drive voltage.

It is yet another object of the present invention to provide a rotation sensing device and a method of manufacturing the same, in which a structural design in which the center of mass of the device does not change when the device is driven is used to reduce noise disturbance.

It is a further object of the present invention to provide a rotation sensing device and a method for manufacturing the same, through which an object of a stable process, low cost and precise structure can be achieved, through an optical mask for manufacturing a symmetric sensing structure.

In order to achieve the above objects, the present invention provides a rotation sensing device comprising a pair of first vibrators disposed symmetrically on a substrate, and a sensing electrode disposed on the substrate and corresponding to the pair of first electrodes. do. The vibrator further includes an electrostatic vibrator, a support element, and an elastic element, the support element is connected to the substrate, the elastic element is connected with the electrostatic vibrator, and causes the electrostatic vibrator to float to a predetermined height from the substrate. It is firmly connected to the support element.

Preferably, the electrostatic vibrator further includes a plurality of masses disposed separately from each other on the electrostatic vibrator to increase the inertia of the electrostatic vibrator.

Preferably, the rotation sensing device further comprises an electrically conductive plate disposed between the substrate and the sensing electrode and connected with the electrostatic vibrating body.

Preferably, the electrostatic vibrating bodies of the pair of first vibrating bodies are connected to each other.

Preferably, the rotation sensing device further comprises a pair of second vibrators disposed orthogonally to the pair of first vibrators, the first and second vibrator pairs corresponding to the sensing electrodes. The electrostatic bodies of the first and second vibrator pairs are each electrically connected to each other. At least one side of the pair of first vibrators and its adjacent side of the pair of second vibrators have a comb-like electrode structure that is reciprocated with each other.

To achieve the above objects, the present invention provides a method of forming a first conductive layer on a substrate, forming an insulating layer on the first conductive layer, and removing a portion of the insulating layer to form a groove. Forming a sacrificial layer on the insulating layer, filling the groove, removing the sacrificial layer filled in the groove to form the contact hole, forming a second conductive layer on the sacrificial layer, and filling the contact hole. A method of manufacturing a rotation sensing device further comprising the steps of: etching a portion of the second conductive layer to form at least a pair of electrostatic vibrating structures, and removing the sacrificial layer.

Preferably, the method further comprises forming at least an inertial array layer on the pair of electrostatic vibrating structures.

Preferably, the method further comprises forming a third conductive layer disposed between the substrate and the first conductive layer and in communication with the electrostatic vibrating structure.

Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

1 is a schematic diagram showing a preferred embodiment of a rotation sensing device according to the present invention. The rotation sensing device 2 includes a pair of first vibrators 21a and 21b, a pair of second vibrators 22a and 22b, and a sensing electrode 23. The structure of the pair of first vibrators 21a and 21b is the same as that of one of the pair of second vibrators 22a and 22b. The pair of first vibrators 21a and 21b and the pair of second vibrators 22a and 22b are disposed symmetrically on the substrate and spaced apart from the substrate at an appropriate height (not shown). The pair of first vibrators 21a and 21b are orthogonal to the pair of second vibrators 22a and 22b.

Reference is made to Figure 2, which is a structural diagram of a vibrator of a preferred embodiment of a rotation sensing device according to the present invention. In the following, the vibrator 21a is taken as an example for explaining the detailed structure. The vibrator 21a includes an electrostatic vibrator 211, a support element 212, and an elastic element 213. The electrostatic vibrator 211 is an electrically conductive material. The support element 212 is disposed at the center of mass of the electrostatic vibrator 211 and is connected to the substrate 20. The elastic element 213 is connected to the electrostatic vibrator 211, and is firmly connected to the support element 212 to cause the electrostatic vibrator 211 to float to a predetermined height from the substrate 20. The purpose of the elastic element 213 is to allow the electrostatic vibrator 211 to vibrate back and forth along the first direction 6, and the electrostatic vibrator 211 moves in the second direction 9 while the vibrator 21a is activated. ) To prevent it from vibrating.

In order to limit the direction of vibration and to provide sufficient floating strength of the electrostatic vibrating body 211, in this embodiment, the elastic element 213 has a connecting bar 2130 and four rods 2131 to 2134. It is designed, but not limited to. The same side of the end of the four rods 2131 to 2134 is connected to the connection bar 2130, the two outer rods 2131 and 2132 are firmly connected to the electrostatic vibrating body 211, the two outer rods Two rods 2133 and 2134 between 2131 and 2132 are firmly connected to the support element 212. Due to the high aspect ratio of the four rods 2131-2134, it will be effective and easy to control the electrostatic elastomer 211 to vibrate along the first direction 6 and to provide greater floating strength. In this embodiment, the electrostatic vibrator 211 has a symmetrical centerline through the connecting position of the elastic element 213 and the support element 212.

The electrostatic vibrator 211 further includes a plurality of masses 214 disposed separately from each other on the electrostatic vibrator 211 to increase the inertia of the electrostatic vibrator 211. The mass 214 is made of a conductor material or a semiconductor material. In a preferred embodiment of the present invention, gold (Au) is used as the material of the plurality of masses 214. The feedback comb drive 215 is disposed on one side of the electrostatic vibrating body 211.

Referring again to FIG. 1, at least one side of the pair of first vibrators 21a and 21b and its adjacent pair of second vibrators 22a and 22b, in order to enhance the electrostatic force to increase the vibration effect. The side has a comb-like electrode structure 26 interchanged with each other. The sensing electrodes 23 are disposed on the substrate 20 at positions corresponding to the pair of first vibrators 21a and 21b and the pair of second vibrators 22a and 22b. The feedback electrode portion 24 used for the closed loop control while the electrostatic vibrators 211, 211 ′, 221, and 221 ′ vibrate includes a comb electrode structure 241, where the comb electrode structure 241 is It interlocks with feedback comb drives 215, 215 ', 225, 225'.

After the pair of first vibrators 21a and 21b and the pair of second vibrators 22a and 22b are activated, the rotation sensing device 2 is caused by vibration in a direction perpendicular to the substrate 20. Rather than the Coriolis force, it will generate vibrations caused by parasitic effects between the vibrators 21a, 21b, 22a, 22b and the substrate 20, where the parasitic effects are induced by the pseudo change between the lead and the substrate 20. . In order to prevent the sensing result from being affected by the parasitic effect, the electrostatic vibrators 211, 211 ′, 221, An electrically conductive plate connected to 221 ′ is disposed between the substrate 20 and the sensing electrode 23. In Fig. 2, the vibrator 21a is taken as an example for explaining the relationship between the electrostatic vibrator 211 and the electrically conductive plate 25, while the illustrated region of the electrically conductive plate 25 is a schematic for explanation. This is just an example, and will not be limited to the form of the electrically conductive plate shown in FIG.

The method of manufacturing a rotation sensing device will now be shown in FIGS. 3A-3H, which are flowcharts showing a preferred embodiment of a method for manufacturing a rotation sensing device without an electrically conductive plate. First, a first conductive layer 312 is formed on the substrate 311, which is shown in FIG. 3A. Next, an insulating layer 321 is attached on the first conductive layer 312, and a portion of the insulating layer 321 is removed to form the groove 331, which is shown in FIG. 3B. Subsequently, forming a sacrificial layer 341 on the insulating layer 321 and filling the groove 331 is shown in FIG. 3C. Thereafter, as shown in FIG. 3D, the sacrificial layer 341 filled in the groove 331 is removed to form the contact hole 351.

Thereafter, forming the first conductive layer 361 on the sacrificial layer 341 and filling the contact hole 351 is shown in FIG. 3E. Referring next to FIG. 3F, etching a portion of the second conductive layer 361 is shown to form at least a pair of electrostatic vibrating structures 371. Thereafter, forming at least an inertial array layer 381 on the pair of electrostatic vibrating structures 371 is shown in FIG. 3G. Finally, FIG. 3H illustrates removing the sacrificial layer 341 to form a rotation sensing device.

Hereinafter, another manufacturing flow of the rotation sensing device including the electrically conductive plate is shown in Figs. 4A to 4I. First, a third conductive layer 41 is formed on the substrate 40, and an insulating layer 42 is attached on the third conductive layer 41, which is shown in Fig. 4A. A first conductive layer 43 is then formed on the insulating layer 42, which is shown in FIG. 4B. Next, an insulating layer 44 is attached on the first conductive layer 43, and a portion of the insulating layer 44 is removed to form the grooves 441, which is shown in FIG. 4C. Thereafter, forming the sacrificial layer 45 on the insulating layer 44 and filling the groove 441 is shown in FIG. 4D. Thereafter, as shown in FIG. 4E, the sacrificial layer 45 filled in the groove 441 is removed to expose a portion of the third conductive layer 41 and form the contact hole 451.

4F then forms a second conductive layer 46 on the sacrificial layer 45 and fills the contact hole 451 to bring the second conductive layer 46 into contact with the third conductive layer 41. Shows the steps. 4G, a step of etching a portion of the second conductive layer 46 to form at least a pair of electrostatic vibrating structures 48 is shown. Thereafter, forming at least an inertial array layer 47 on the pair of electrostatic vibrating structures 48 is shown in FIG. 4H. Finally, FIG. 4I illustrates removing the sacrificial layer 46 to form a rotation sensing device.

3A-3H and 4A-4I, SiO ₂ is used as the material of the sacrificial layers 341 and 45, and Si ₃ N ₄ is used as the material of the insulating layers 321, 42 and 44. . The inertial array layers 381 and 47 are made of a conductor material or a semiconductor material, and in this embodiment, a conductor material of gold (Au) is selected.

After understanding the structure and manufacturing method of the present invention, the detailed operation of the present invention will be described. Fig. 5A is a schematic diagram showing the operation of the preferred embodiment of the rotation sensing device according to the present invention. The rotation sensing device 2 can measure rotation about two axes, which is Ω x on the x axis and Ω y on the y axis in this embodiment. When the pair of first vibrators 21a and 21b have positive charges and the pair of second vibrators 22a and 22b have negative charges, they occur between the vibrators 21a and 22a and between the vibrators 21b and 22b. There will be electrostatic attraction. In contrast, when the pair of first vibrators 21a and 21b have negative charges and the pair of second vibrators 22a and 22b have positive charges, between the vibrators 21a and 22a and between the vibrators 21b and 22b. There will be an electrostatic repulsion occurring between them.

By the above-mentioned principle of generating vibration, the drive circuit 27 so that electrostatic attraction and repulsive force can be generated between the pair of first vibrators 21a and 21b and the pair of second vibrators 22a and 22b. ) Is employed to provide an AC electric field to the pair of first vibrators 21a, 21b and a DC electric field to the pair of second vibrators 22a, 22b. Electrostatic attraction and repulsive force can be divided into X- and Y-axis components. Due to the high aspect ratio structure of the elastic element 213, the electrostatic vibrating bodies 211, 211 ', 221, 221' are limited to vibrate in a direction parallel to the substrate (not shown). In order to control the oscillation frequency to produce a good resonance effect, the present invention utilizes a closed loop control circuit 8 in connection with the feedback electrode portion 24. Therefore, control is achieved by feeding back the closed loop control circuit 8 in the vibration mode, which is sensed by the feedback electrode portion 24 of the electrostatic vibrators 211, 211 ′. Since the structures of the vibrators are identical to each other, the structures of the vibrators have the same vibration mode to generate a resonance effect that reduces the power to drive the electrostatic force. In addition, the center of mass of the electrostatic vibrator will not change during vibration so that noise disturbances can be reduced to make the demodulation process more stable.

이다. 도5b를 참조하면, x축의 회전이 발생하는 동안, 본 발명 의 회전 감지 장치의 한 쌍의 제1 진동기에 영향을 미치는 코리올리력을 도시하는 측면도이다. 진동이, 한 쌍의 제1 진동기(21a, 21b)와 한 쌍의 제2 진동기(22a, 22b) 사이의 정전기력에 의해 구동되는 조건에서, 한 쌍의 제1 진동기(21a, 21b)는, 회전 감지 장치가 x축의 회전의 각속도에 의해 영향을 받는 경우, 코리올리력에 의해 기판에 수직으로 요동될 것이다. 한 쌍의 제1 진동기(21a, 21b)의 요동이 한 쌍의 제1 진동기(21a, 21b)에서 감지 전극(23)으로의 수직 거리를 변화시켜, 한 쌍의 제1 진동기(21a, 21b)와 감지 전극(23) 사이의 커패시턴스가 변화될 것이다. 커패시턴스 변화량 ΔC1 및 ΔC2가 감지 전극(26)에 의해 검출될 수 있고, 회전의 크기가 전기 신호를 통해 반영될 것이다.The speed V is provided by vibration due to electrostatic force between the pair of first vibrators 21a and 21b and the pair of second vibrators 22a and 22b, and the Coriolis force is applied to the angular velocity Ω of the rotation at which the sensing device is to be measured. Will occur if affected by Coriolis

to be. 5B is a side view showing the Coriolis force affecting the pair of first vibrators of the rotation sensing device of the present invention while the rotation of the x-axis occurs. The pair of first vibrators 21a and 21b rotates under the condition that the vibration is driven by an electrostatic force between the pair of first vibrators 21a and 21b and the pair of second vibrators 22a and 22b. If the sensing device is affected by the angular velocity of rotation of the x-axis, it will oscillate perpendicular to the substrate by the Coriolis force. The fluctuations of the pair of first vibrators 21a and 21b change the vertical distance from the pair of first vibrators 21a and 21b to the sensing electrode 23, so that the pair of first vibrators 21a and 21b. And the capacitance between the sensing electrode 23 will change. The capacitance change amounts ΔC1 and ΔC2 can be detected by the sensing electrode 26, and the magnitude of the rotation will be reflected through the electrical signal.

Figure 6 is a schematic diagram showing another preferred embodiment of the rotation sensing device according to the present invention, which employs only one pair of vibrators, for example a pair of first vibrators. A pair of vibrators 21a and 21b can be used to measure rotation about one axis. In this example, the pair of stationary electrodes 1 (not shown) disposed on the substrate are interlocked with the comb-shaped electrode structures 216 of the vibrators 21a and 21b, so that the pair of first vibrators 21a, 21b) can be driven to generate vibrations. The vibrator 21a is electrically connected to the vibrator 21b, and the stationary electrodes 1 are connected to each other. Thus, the electrostatic attraction and repulsive force between the pair of first vibrators and the stationary electrode along the first direction 6 are such that an AC electric field is provided to the pair of first vibrators 21a, 21b, and the DC electric field is If provided to a pair of second vibrators 22a, 22b, it can be generated to detect rotation about an axis.

Although the preferred embodiments of the present invention have been described for purposes of disclosure, other embodiments, as well as variations to the disclosed embodiments of the present invention, may be made by those skilled in the art. Accordingly, the following claims are intended to cover all embodiments without departing from the spirit and scope of the invention.

According to the present invention, it is possible to provide a rotation sensing device and a manufacturing method thereof, in which a rotation sensing device having a stable center of mass is driven to generate driving vibrations. Furthermore, according to the present invention, it is possible to provide a rotation sensing device and a method for manufacturing the same, in which the device can be manufactured by MEMS process technology. Furthermore, according to the present invention, when the apparatus is driven so that the reduction of noise disturbance is achieved, it is possible to provide a rotation sensing apparatus and a manufacturing method thereof, in which a structural design in which the center of mass of the apparatus does not change is used. Furthermore, according to the present invention, through the optical mask for manufacturing the symmetrical sensing structure, it is possible to provide a rotation sensing device and a method of manufacturing the same, in which the purpose of a stable process, low cost and precise structure can be achieved.

Claims (8)

A pair disposed symmetrically on a substrate, each comprising an electrostatic vibrator, a support element connected to the substrate, and an elastic element rigidly connected to the support element such that the electrostatic vibrator floats a predetermined height away from the substrate. A first vibrator; And And a sensing electrode disposed on the substrate and corresponding to the pair of first vibrators. The rotation sensing apparatus according to claim 1, wherein the electrostatic vibrator further comprises a plurality of mass bodies disposed separately from each other on the electrostatic vibrator to increase the inertia of the electrostatic vibrator. The rotation sensing device of claim 1, further comprising an electrically conductive plate disposed between the substrate and the sensing electrode and connected to the electrostatic vibrating body. The method of claim 1, further comprising a pair of second vibrators disposed orthogonally to the pair of first vibrators on the substrate, wherein the first and second vibrator pairs correspond to the sensing electrodes. Rotation sensing device. 5. The rotational sensing device of claim 4, wherein at least one side of the pair of first vibrators and adjacent sides of the pair of second vibrators each have a comb-like electrode structure interlaced with each other. Forming a first conductive layer on the substrate; Forming an insulating layer on the first conductive layer; Removing a portion of the insulating layer to form a groove; Forming a sacrificial layer on the insulating layer to fill the grooves; Removing the sacrificial layer filled in the groove to form a contact hole; Forming a second conductive layer on the sacrificial layer to fill the contact hole; Etching a portion of the second conductive layer to form at least a pair of electrostatic vibrating structures; And Removing the sacrificial layer. 7. The method of claim 6, further comprising forming at least an inertial array layer on the pair of electrostatic vibrating structures. The method of claim 6, further comprising forming a third conductive layer disposed between the substrate and the first conductive layer and connected to the electrostatic vibrating structure.

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