Photoelectric induction acceleration sensor and manufacturing method thereof

Abstract

The present invention provides a photoelectric inertial sensor and a manufacturing method thereof. The photoelectric inertial sensor comprises a fixed base and an inertial body. The fixed base has a closed cavity. The inertial body is located in the cavity and has a gap with the cavity. The inertial body is connected to the fixed base through an elastic device. The inertial body can vibrate along the X-axis direction in the cavity. The first surface of the inertial body has an optical waveguide arranged along the Y-axis direction. The first inner surface of the fixed base opposite to the first surface of the inertial body has a plurality of photoelectric sensing units and a light guide device arranged along the X-axis direction. The outgoing light beam of the light guide device is incident on the optical waveguide of the inertial body along the Z-axis direction. The optical waveguide in the inertial body transmits the incident light beam along the Y-axis direction of the optical waveguide and emits it to the photoelectric sensing unit along the Z-axis direction. When the inertial body vibrates along the X-axis direction, at least a part of the light beam is incident on the optical waveguide, and the outgoing light beam of the optical waveguide is received by at least one photoelectric sensing unit.

Description

Technical Field

[0001] The present application relates to the field of acceleration sensors, and in particular to a photoelectric acceleration sensor and a manufacturing method thereof. Background Art

[0002] Accelerometer is a sensor widely used in various motorized equipment and even mobile terminals and electronic systems. It is used to sense the current motion acceleration of the carrier and infer the linear velocity and important motion data to effectively support the real-time control of the carrier's motion. Today, accelerometers, especially MEMS accelerometers based on silicon semiconductors, have many advantages such as miniaturization, low cost, and high reliability. The application market has expanded from the initial high-end traditional system applications such as aircraft and automobiles to various mobile terminals and portable electronic systems on a large scale.

[0003] MEMS motion sensors usually have at least one silicon inertial body in a cavity made on a single crystal silicon substrate. The silicon inertial body is suspended in the cavity by multiple unidirectional flexible springs and connected to the silicon substrate. The relative motion between the two is sensed by the electrical effect generated by the change in the distance between the two. For this reason, although in the process of relative operation, the inertial body and the substrate need to be coordinated to have a senseable electrical effect. Therefore, silicon-based MEMS motion sensors all use an inertial body composed of multiple micro-plates that are opposite to the micro-plates of the substrate to form a flat plate capacitor with a large enough area. As the two move relative to each other, the change in the distance between the plates causes the change in the flat plate capacitance. Therefore, the relative displacement and acceleration data between the inertial body and the substrate are inferred by sensing the change in capacitance.

[0004] It is important to note that, since relative motion is characterized by the change in capacitance between multiple parallel plates that move relative to each other, traditional MEMS acceleration is bound to have the following problems: relative displacement can only be limited to a very small range, neither too large nor too small, in order to keep the capacitance between the plates within a measurable range, usually 0.1 to 10um; the mass of the inertial body and the elastic coefficient of the elastic connector are relatively small, so the natural frequency is relatively high; the acceleration data is a secondary extrapolation, and the system error is relatively large. Summary of the invention

[0005] In order to solve the above-mentioned product performance problem, the present invention provides a photoelectric induction acceleration sensor and a manufacturing method thereof.

[0006] The present invention provides a photoelectric induction acceleration sensor and a manufacturing method thereof. The sensor takes a Cartesian vertical coordinate system as a reference and comprises a fixed base and an inertial body. The fixed base has a closed cavity. The inertial body is located in the cavity and has a gap with the cavity. The inertial body is connected to the fixed base through an elastic device. The inertial body can vibrate along the X-axis direction in the cavity. The first surface of the inertial body has an optical waveguide arranged along the Y-axis direction. The first inner surface of the fixed base opposite to the first surface of the inertial body has a plurality of photoelectric sensing units and a light guide arranged along the X-axis direction. The outgoing light beam of the light guide device is incident on the optical waveguide of the inertial body along the Z-axis direction. The optical waveguide in the inertial body transmits the incident light beam along the Y-axis direction of the optical waveguide and emits it to the photoelectric sensing unit along the Z-axis direction. When the inertial body vibrates along the X-axis direction, at least a part of the light beam is incident on the optical waveguide, and the outgoing light beam of the optical waveguide is received by at least one photoelectric sensing unit.

[0007] The photoelectric induction acceleration sensor of the present invention, due to the use of photoelectric induction technology, greatly reduces the lowest sensed acceleration, expands the sensing range, has the advantages of being direct, accurate and unlimited, and has strong resistance to electromagnetic interference and is not affected by factors such as algorithms. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0009] Figure 1 It is a three-dimensional schematic diagram of a first embodiment of a photoelectric inertial sensor of the present invention;

[0010] Figure 2 It is a cross-sectional schematic diagram along the line AA' of the first embodiment of the photoelectric inertial sensor of the present invention;

[0011] Figure 3 It is a cross-sectional schematic diagram along BB' of the first embodiment of the photoelectric inertial sensor of the present invention;

[0012] Figure 4 A schematic diagram of a process of manufacturing a photoelectric inertial sensor according to an embodiment of the present invention;

[0013] Figure 5a-5f A schematic cross-sectional view along line AA' of a process of preparing a photoelectric inertial sensor according to an embodiment of a method for manufacturing a photoelectric inertial sensor of the present invention;

[0014] Figure 6The cross-sectional view along the line BB' is a schematic diagram of a process of forming an optical waveguide during the process of preparing a photoelectric inertial sensor according to an embodiment of the method for manufacturing a photoelectric inertial sensor of the present invention. DETAILED DESCRIPTION

[0015] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0016] In the present invention, unless otherwise specified, the directional words used, such as "upper and lower", generally refer to the upper and lower parts of the device in normal use, and "inside and outside" refer to the outline of the device. In addition, the terms "first, second, third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first, second, third" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In the present invention, it is an electrical device, so connection and interconnection both refer to conductive interconnection. Since the accompanying drawings are descriptions of the same device, the same numbers in the drawings represent the same components.

[0017] The specific examples of the present invention are further described in detail below with reference to the accompanying drawings.

[0018] The embodiment of the present disclosure provides a photoelectric sensing inertial sensor, which uses a Cartesian vertical coordinate system as a reference, and includes a fixed base and an inertial body. The fixed base has a closed cavity, the inertial body is located in the cavity, and has a gap with the cavity. The inertial body is connected to the fixed base through an elastic device, and the inertial body can vibrate along the X-axis direction in the cavity; the first surface of the inertial body has an optical waveguide arranged along the Y-axis direction; the first inner surface of the fixed base opposite to the first surface of the inertial body has a plurality of photoelectric sensing units and a light guide device arranged along the X-axis direction, and the outgoing light beam of the light guide device is incident on the optical waveguide of the inertial body along the Z-axis direction; the optical waveguide in the inertial body transmits the incident light beam along the Y-axis direction of the optical waveguide, and emits it to the photoelectric sensing unit along the Z-axis direction; when the inertial body vibrates along the X-axis direction, at least a part of the light beam is incident on the optical waveguide, and the outgoing light beam of the optical waveguide is received by at least one photoelectric sensing unit.

[0019] Specifically, Figure 1 FIG. 1 shows a perspective schematic diagram of a photoelectric inertial sensor according to an embodiment of the present disclosure, Figure 2 FIG. 4 is a schematic cross-sectional view of a photoelectric inertial sensor along the line AA′ according to an embodiment of the present disclosure. Figure 1 and Figure 2, with the Cartesian vertical coordinate system as a reference, the photoelectric inertial sensor 10 includes a fixed base 100 and an inertial body 200, the fixed base 100 has a closed cavity 110, the inertial body 200 is located in the cavity 110, connected to the fixed base 100 through an elastic device 300, and can vibrate along the X-axis direction in the cavity 110; an optical waveguide 210 along the Y-axis direction is arranged on the first surface of the inertial body 200; the first inner surface of the fixed base 100 opposite to the first surface of the inertial body 200 has a plurality of photoelectric sensing units 120 and optical waveguides arranged along the X-axis direction. The light beam is emitted from the light guide device 130, and the outgoing light beam of the light guide device 130 is incident on the optical waveguide 210 in the inertial body 200 along the Z-axis direction; the optical waveguide 210 in the inertial body 200 transmits the incident light beam along the Y-axis direction, and emits it to the photoelectric sensing unit 120 along the Z-axis direction; when the fixed base 100 and the inertial body 200 move relative to each other, the inertial body 200 vibrates along the X-axis direction, then at least a part of the light beam is incident on the optical waveguide 210 from the light guide device 130, and the outgoing light beam of the optical waveguide 210 is received by at least one photoelectric sensing unit 120.

[0020] In the embodiment of the present disclosure, two elastic devices 300 are respectively provided on the two sides of the inertial body along the X-axis direction. In some other embodiments, there may be a plurality of elastic devices respectively on the two sides of the inertial body along the X-axis direction, for connecting the fixed base and the inertial body.

[0021] In some embodiments, the elastic device may be a zigzag or U-shaped device, which is elastic along the X direction. For example, in a specific embodiment, the photoelectric inertial sensor may include four U-shaped elastic devices, which are respectively arranged on opposite sides of the inertial body along the X-axis direction, that is, two elastic devices are arranged on the edge of each side of the inertial body on the two sides corresponding to each other along the X-axis direction, and the open ends of the U-shaped elastic devices are respectively connected to the inertial body and the fixed base. In some embodiments, the material of the optical waveguide may be a tubular cavity surrounded by silicon compounds or metals. In some other embodiments, the optical waveguide may be a transparent semiconductor material or an optical fiber.

[0022] Figure 3 FIG. 2 shows a schematic cross-sectional view of a photoelectric inertial sensor along the BB' line according to an embodiment of the present disclosure. Figure 3As shown, the photoelectric inertial sensor 10 further includes a first reflecting device 220 and a second reflecting device 230. The first reflecting device 220 is disposed between the light guide device 130 and the optical waveguide 210, and is used to reflect the outgoing light beam along the Z-axis direction in the light guide device 130 to the direction along the optical waveguide 210, so that the outgoing light beam of the light guide device 130 can be injected into the optical waveguide 210 and transmitted in the optical waveguide 210; the second reflecting device 230 is disposed between the photoelectric sensing unit 120 and the optical waveguide 210, and is used to reflect the outgoing light beam along the Y-axis direction in the optical waveguide 210 to the direction along the photoelectric sensing unit 120, so that the outgoing light beam in the optical waveguide 210 can be received by the photoelectric sensing unit 120.

[0023] Specifically, in this embodiment, the first reflection device 220 is disposed at one end of the optical waveguide 210 corresponding to the light guide device 130, and can be specifically a metal reflection film layer, and the reflection surface is at an angle of 45° with the first surface of the inertial body 200, so that the incident light beam along the Z-axis direction is deflected by 90° and then reflected to the Y-axis direction, entering from one end of the optical waveguide 210, and finally emitted from the other end of the optical waveguide 210. A second reflection device 230 is disposed at the other end of the optical waveguide 210, corresponding to the photoelectric sensing unit 120, and can be specifically a metal reflection film layer, and the reflection surface is at an angle of 45° with the first surface of the inertial body 200, so that the outgoing light beam along the Y-axis direction in the optical waveguide 210 is deflected by 90° and then reflected to the photoelectric sensing unit 120.

[0024] In some embodiments, the materials of the first reflecting device and the second reflecting device may be metal and / or dielectric.

[0025] In some embodiments, a plurality of the light guide devices and the photoelectric sensing units may be disposed on the fixed substrate. Figure 1 In the specific embodiment shown, the first inner surface of the fixed base 100 opposite to the first surface of the inertial body 200 has four photoelectric sensing units and four light guide devices arranged along the X-axis direction. In another embodiment, the light guide device can be set as a strip light guide device along the X-axis direction. When the inertial body vibrates along the X-axis relative to the fixed base, the strip light guide device can ensure that part of the light beam can be injected into the optical waveguide. In yet another embodiment, the light guide device may include an array of several light guide units arranged along the X-axis direction. When the inertial body vibrates along the X-axis direction, the light beam of at least one of the light guide units enters the optical waveguide. In different embodiments, the number and shape of the light guide device and the photoelectric sensing unit can be adjusted according to the specifications of different photoelectric sensing inertial sensors, which is not limited in the embodiments disclosed herein.

[0026] In some embodiments, the photoelectric sensing unit may include at least one photodiode and a transistor connected to the photodiode, wherein the transistor is used to switch or amplify the photoelectron signal generated by the photodiode.

[0027] In some embodiments, the cavity is filled with lubricating gas and / or lubricating liquid.

[0028] In some embodiments, the material of the fixed base and the inertial body may be a silicon compound, and the material of the light guide device may be a silicon compound or a metal.

[0029] The photoelectric inertial sensor provided in the embodiment of the present disclosure adopts photoelectric induction technology, which greatly reduces the minimum sensed acceleration, thereby expanding the sensing range; it has the advantages of being direct, accurate and unlimited, and at the same time has strong resistance to electromagnetic interference and is not affected by factors such as algorithms.

[0030] The present disclosure also provides a method for manufacturing a photoelectric inertial sensor. Figure 4 The schematic diagram of the process of manufacturing the photoelectric inertial sensor of the embodiment of the present disclosure is shown. Figure 5a-5f The schematic diagram of the cross-sectional structure along line A-A' of the process of forming a photoelectric inertial sensor according to the manufacturing method of the embodiment of the present disclosure is shown. Figure 4 as well as Figure 5a to Figure 5f , the manufacturing method of the photoelectric inertial sensor of the present invention is described in detail.

[0031] The manufacturing method of the photoelectric inertial sensor of the present invention specifically comprises the following steps:

[0032] S1: providing a first substrate.

[0033] S3: etching the first substrate to form a first groove.

[0034] S5: forming a first sacrificial layer in the first groove.

[0035] like Figure 5a In this embodiment, a first substrate 500 is first formed, and the first substrate 500 is a silicon substrate. Then, a first groove is etched on the first substrate 500, and a first sacrificial layer 510 is formed in the first groove; the material of the first sacrificial layer 510 can be a photoresist material.

[0036] In some other embodiments, the first substrate may be a semiconductor substrate made of other materials.

[0037] S7: etching the first sacrificial layer to form a second groove and a third groove connecting the first substrate and the second groove, the second groove corresponds to the inertial body, and the third groove corresponds to the elastic device.

[0038] S9: forming a first semiconductor layer in the second groove and the third groove, wherein the first semiconductor layer in the second groove is used to form an inertial body, and the first semiconductor layer in the third groove is used to form an elastic device.

[0039] Reference Figure 5b A second groove and a third groove are formed on the first sacrificial layer 510 by etching process, wherein the third groove connects the first substrate 500 and the second groove, wherein the third groove is a folded line groove along the X-axis direction. Figure 5b Only the cross-sectional schematic diagram of the third groove along BB' is shown. Next, a first semiconductor layer is formed in the second groove and the third groove, the first semiconductor layer in the second groove is used to form an inertial body, and the first semiconductor layer in the third groove is used to form an elastic device 520.

[0040] In the embodiment of the present disclosure, the elastic device 520 is a folded line structure. In some other embodiments, a U-shaped elastic device having elasticity along the X direction may also be provided.

[0041] In some embodiments, the material of the first semiconductor layer may be silicon nitride, silicon oxide, or the like.

[0042] S11: forming an optical waveguide along the Y-axis direction on the surface of the first semiconductor layer.

[0043] Specifically, Figure 6 The cross-sectional structure schematic diagram along the line BB' of forming an optical waveguide in the process of preparing a photoelectric inertial sensor according to the manufacturing method disclosed in the present invention is shown. Figure 5c and Figure 6 First, a first metal layer 531 is formed along the Y-axis direction on the surface of the first semiconductor layer in the second groove. Further, reflective layers 532 and 533 are formed at 45° angles with the first metal layer 531 at both ends of the first metal layer 531. After that, a transparent light-guiding medium 534 is deposited on the surface of the first metal layer 531 and the reflective layers 532 and 533, and then the light-guiding medium 534 is etched to form a groove, which is filled with metal, and a second metal layer 535 is formed on the surface of the transparent light-guiding medium 534, thereby forming an optical waveguide 530.

[0044] In the embodiment of the present disclosure, the first semiconductor layer and the optical waveguide 530 in the second groove together form an inertial body 540 .

[0045] In some embodiments, the reflective layer may be formed during the process of depositing the first metal layer by etching the first semiconductor layer in the second groove to form an oblique angle before forming the first metal layer.

[0046] In some embodiments, the materials of the first metal layer and the second metal layer may be copper, aluminum, etc. In other embodiments, optical fibers may be directly laid to form the optical waveguide.

[0047] S13: forming a second sacrificial layer, wherein the second sacrificial layer completely covers the inertial body, the elastic device and the first sacrificial layer.

[0048] S15: forming a second semiconductor layer on the surface of the second sacrificial layer.

[0049] Steps S13-S15 can refer to Figure 5d First, a second sacrificial layer 550 is formed on the surface of the inertial body 540 , the elastic device 520 and the first sacrificial layer 510 ; the material of the second sacrificial layer 550 may be a photoresist material. Then, a second semiconductor layer 560 is formed on the second sacrificial layer 550 , so that the second semiconductor layer 560 completely covers the second sacrificial layer 550 and the first substrate 500 .

[0050] S17: forming a photoelectric sensing unit and a photoconductive device in the second semiconductor layer.

[0051] Specifically, a plurality of photoelectric sensing units and light guide devices are formed in the second semiconductor layer 560 along the X-axis direction.

[0052] S19: etching the second semiconductor layer to form a through hole connected to the second sacrificial layer.

[0053] In the embodiments of the present disclosure, Figure 5e , etching is performed on the surface of the second semiconductor layer 560 to form a plurality of through holes 570 connected to the second sacrificial layer 560 .

[0054] S21: removing the first sacrificial layer and the second sacrificial layer to form a cavity and fill the through hole.

[0055] Reference Figure 5f The first sacrificial layer 510 and the second sacrificial layer 550 are etched through the through hole 570 to form a cavity 580. Thereafter, a capping layer 590 is formed on the second semiconductor layer 560 to fill the through hole 570.

[0056] In some embodiments, the cover layer may be formed by one or any combination of sheet bonding, bonding, physical vapor deposition, and chemical vapor deposition methods.

[0057] In some embodiments, before filling the through hole, the cavity 580 may be filled with lubricating gas, lubricating liquid, or a mixture of gas and liquid.

[0058] As described above, according to a method for manufacturing a photoelectric inertial sensor in an embodiment of the present disclosure, the formed photoelectric inertial sensor adopts photoelectric sensing technology, reduces the minimum sensed acceleration, expands the sensing range, has the advantages of being direct, precise and unlimited, and at the same time has strong resistance to electromagnetic interference and is not affected by factors such as algorithms.

[0059] The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural or equivalent process transformations made using the contents of the specification and drawings of the present application, such as the mutual combination of technical features between the embodiments, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for manufacturing a photoelectric inertial sensor, characterized in that: include: providing a first substrate; Etching the first substrate to form a first groove; forming a first sacrificial layer in the first groove; Etching the first sacrificial layer to form a second groove and a third groove connecting the first substrate and the second groove, the second groove corresponds to the inertial body, and the third groove corresponds to the elastic device; forming a first semiconductor layer in the second groove and the third groove, wherein the first semiconductor layer in the second groove is used to form an inertial body, and the first semiconductor layer in the third groove is used to form an elastic device; forming an optical waveguide along the Y-axis direction on the surface of the first semiconductor layer; forming a second sacrificial layer, wherein the second sacrificial layer completely covers the inertial body, the elastic device and the first sacrificial layer; forming a second semiconductor layer on a surface of the second sacrificial layer; forming a photoelectric sensing unit and a photoconductive device in the second semiconductor layer; Etching the second semiconductor layer to form a through hole communicating with the second sacrificial layer; The first sacrificial layer and the second sacrificial layer are removed to form a cavity to fill the through hole.

2. A photoelectric inertial sensor formed by the manufacturing method according to claim 1, characterized in that: Taking the Cartesian vertical coordinate system as a reference, the invention comprises a fixed base and an inertial body, wherein the fixed base has a closed cavity, the inertial body is located in the cavity and has a gap with the cavity, the inertial body is connected to the fixed base through an elastic device, and the inertial body can vibrate along the X-axis direction in the cavity; the first surface of the inertial body has an optical waveguide arranged along the Y-axis direction; the first inner surface of the fixed base opposite to the first surface of the inertial body has a plurality of photoelectric sensing units and a light guide device arranged along the X-axis direction, the outgoing light beam of the light guide device is incident on the optical waveguide of the inertial body along the Z-axis direction; the optical waveguide in the inertial body transmits the incident light beam along the Y-axis direction of the optical waveguide, and emits it to the photoelectric sensing unit along the Z-axis direction; when the inertial body vibrates along the X-axis direction, at least a part of the light beam is incident on the optical waveguide, and the outgoing light beam of the optical waveguide is received by at least one photoelectric sensing unit.

3. The photoelectric inertial sensor according to claim 2, characterized in that: It comprises at least two elastic devices arranged on two side surfaces of the inertial body along the X-axis direction.

4. The photoelectric inertial sensor according to claim 3, characterized in that: The elastic device is in a zigzag shape or a U-shape and has elasticity along the X direction.

5. The photoelectric inertial sensor according to claim 4, characterized in that: It comprises four elastic devices, two of which are arranged on the edge of each side of the inertial body along the X-axis direction, and the elastic device is U-shaped, with the open ends respectively connected to the inertial body and the fixed base.

6. The photoelectric inertial sensor according to claim 2, characterized in that: A first reflecting device is arranged between the light guiding device and the optical waveguide tube, and is used to reflect the incident light beam along the Z-axis direction to the direction along the optical waveguide tube.

7. The photoelectric inertial sensor according to claim 6, characterized in that: The reflection surface of the first reflection device and the first surface of the inertial body form an angle of 45°, and the material of the first reflection device is metal and / or dielectric.

8. The photoelectric inertial sensor according to claim 2, characterized in that: A second reflecting device is arranged between the photoelectric sensing unit and the optical waveguide, and is used to reflect the outgoing light beam of the optical waveguide to a direction along the photoelectric sensing unit.

9. The photoelectric inertial sensor according to claim 8, characterized in that: The reflection surface of the second reflection device and the first surface of the inertial body form an angle of 45°, and the material of the second reflection device is metal and / or dielectric.

10. The photoelectric inertial sensor according to claim 9, characterized in that: The photoelectric sensing unit includes at least one photodiode.

11. The photoelectric inertial sensor according to claim 10, characterized in that: The photoelectric sensing unit includes a transistor connected to the photodiode, which is used to switch or amplify the photoelectron signal generated by the photodiode.

12. The photoelectric inertial sensor according to claim 2, characterized in that: The light guide device comprises a plurality of light guide unit arrays arranged along the X-axis direction. When the inertial body vibrates along the X-axis direction, a light beam from at least one light guide unit enters the optical waveguide tube.

13. The photoelectric inertial sensor according to claim 2, characterized in that: The material of the optical waveguide is a tubular cavity surrounded by silicon compounds or metals.

14. The photoelectric inertial sensor according to claim 2, characterized in that: The optical waveguide is made of transparent semiconductor material or optical fiber.

15. The photoelectric inertial sensor according to claim 2, characterized in that: The cavity is filled with lubricating gas and / or lubricating liquid.

16. The photoelectric inertial sensor according to claim 2, characterized in that: The material of the fixed base and / or the inertial body is a silicon compound.

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