阅读说明：本技术 一种低横向灵敏度的法布里珀罗光学mems加速度传感器 (Fabry-Perot optical MEMS acceleration sensor with low lateral sensitivity ) 是由 韦学勇 赵明辉 蒋康力 蒋庄德 于 2019-12-02 设计创作，主要内容包括：一种低横向灵敏度的法布里珀罗光学MEMS加速度传感器,包括基座,基座的上面和传感器壳体连接形成腔室,腔室内的基座上连接半导体制冷片,半导体制冷片的上方连接有第二支架,第二支架的内部连接有激光二极管,半导体制冷片上表面与激光二极管粘接,第二支架的上方连接有敏感芯片,敏感芯片的上方连接有第一支架,第一支架的上方连接有光电检测芯片及其电路板；敏感芯片为MEMS法布里珀罗光学弹簧质量结构,由可动镜面、腔体、固定镜面形成法布里珀罗腔；本发明采用法布里珀罗干涉光学加速度检测方式,结合闭环温度控制系统,具有高分辨率和灵敏度；敏感芯片采用分体式弹簧质量结构,有效隔绝横向加速度,降低了传感器的横向灵敏度。(A Fabry-Perot optical MEMS acceleration sensor with low lateral sensitivity comprises a base, wherein the upper surface of the base is connected with a sensor shell to form a cavity, a semiconductor refrigerating sheet is connected onto the base in the cavity, a second support is connected above the semiconductor refrigerating sheet, a laser diode is connected inside the second support, the upper surface of the semiconductor refrigerating sheet is bonded with the laser diode, a sensitive chip is connected above the second support, a first support is connected above the sensitive chip, and a photoelectric detection chip and a circuit board thereof are connected above the first support; the sensitive chip is an MEMS Fabry-Perot optical spring mass structure, and a Fabry-Perot cavity is formed by a movable mirror surface, a cavity body and a fixed mirror surface; the invention adopts a Fabry-Perot interference optical acceleration detection mode, combines a closed-loop temperature control system, and has high resolution and sensitivity; the sensitive chip adopts a split spring mass structure, so that the transverse acceleration is effectively isolated, and the transverse sensitivity of the sensor is reduced.)

1. A Fabry-Perot optical MEMS acceleration sensor of low lateral sensitivity, comprising a base (7), characterized in that: the upper surface of a base (7) is connected with a sensor shell (1) to form a cavity, a semiconductor refrigerating sheet (5) is connected on the base (7) in the cavity, a second support (3) is connected above the semiconductor refrigerating sheet (5), a laser diode (8) is connected inside the second support (3), the upper surface of the semiconductor refrigerating sheet (5) is bonded with the laser diode (8), a sensitive chip (9) is connected above the second support (3), a first support (2) is connected above the sensitive chip (9), a circuit board (10) is connected above the first support (2), a photoelectric detection chip (11) is connected on the lower surface of the circuit board (10), the semiconductor refrigerating sheet (5), the sensitive chip (9), the circuit board (10) and a first pin group (4) are electrically connected, and the laser diode (8) and a second pin group (6) are electrically connected, the first pin group (4) and the second pin group (6) penetrate through the base (7) and extend out of the cavity.

2. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: the sensitive chip (9) is an MEMS Fabry-Perot optical spring mass structure, a Fabry-Perot cavity is formed by a movable mirror surface (9-1), a cavity body (9-2) and a fixed mirror surface (9-3), when single-frequency laser emitted by a laser diode (8) enters the sensitive chip (9), multiple reflection and transmission can occur in the cavity body, and interference light is finally output; when the sensor is subjected to the action of longitudinal acceleration, the movable mirror surface (9-1) vibrates up and down to cause the cavity length of the Fabry-Perot cavity, namely the distance between the movable mirror surface (9-1) and the fixed mirror surface (9-3) changes, so that the interference phase changes, and the magnitude of the acceleration is obtained by demodulating the variation of the phase; the upper and lower surfaces of the movable mirror surface (9-1) and the fixed mirror surface (9-3) are respectively processed with an infrared light antireflection film formed by silicon nitride and an infrared light antireflection film formed by silicon oxide and germanium, so that the sensitive chip 9 has high optical fineness; in addition, gold electrodes are processed on the upper surfaces of the movable mirror surface (9-1) and the fixed mirror surface (9-3) and used for adjusting the cavity length of the sensitive chip (9) and improving the sensitivity of the sensor.

3. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 2, characterized in that: the movable mirror (9-1) adopts a split spring mass structure and comprises a frame (9-1-1) and a transverse acceleration isolation mass block (9-1-2), the transverse acceleration isolation mass block comprises a spring (9-1-3) and a central mass block (9-1-4), a frame (9-1-1) is connected with the outer side of a transverse acceleration isolation mass block (9-1-2) through the spring (9-1-3), the inner side of the transverse acceleration isolation mass block (9-1-2) is connected with the central mass block (9-1-4) through the spring (9-1-3), and the transverse acceleration isolation mass block (9-1-2) is of a split block structure and is formed by four L-shaped mass blocks which are distributed in a central symmetry mode; the working direction of the movable mirror (9-1), namely the acceleration sensitive direction, is the Z-axis direction, when the movable mirror is subjected to the action of transverse acceleration, the transverse acceleration isolating mass block (9-1-2) is twisted, and the central mass block (9-1-4) is always kept in a horizontal state, so that the transverse sensitivity of the sensor is reduced.

4. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: the upper surface of the semiconductor refrigerating sheet (5) refrigerates and the lower surface releases heat during working; semiconductor refrigeration piece (5) are the cuboid structure, have a through-hole in its positive center for place laser diode (8), form temperature closed loop control system through thermistor and temperature control chip to laser diode (8) are cooled off owing to generating heat that work caused, make the wavelength output of laser diode (8) remain stable, and then reduce the detection noise of sensor, improve sensor measurement accuracy.

5. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: sensor casing (1), first support (2), second support (3) and base (7) jointly use, with semiconductor refrigeration piece (5), laser diode (8), sensitive chip (9) and photoelectric detection chip (11) fixed integration in an organic whole, improved the portable practicality of sensor.

6. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: the laser diode (8) is a Distributed Feedback (DFB) laser diode and is integrated with a convergent lens.

7. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: the lower surface of the second bracket (3) is provided with a groove with the same shape and specification as the laser diode (8).

8. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: the first pin group (4) comprises 8 wiring pins which respectively provide wiring points for the semiconductor refrigerating sheet (5), the sensitive chip (9) and the circuit board (10); the second pin group (6) comprises 4 wiring pins which are electrified wiring points of the laser diode (8).

9. A fabry perot optical MEMS acceleration sensor of low lateral sensitivity according to claim 1, characterized in that: the shell (1) and the base (7) are made of aluminum.

Technical Field

The invention relates to the technical field of Micro Electro Mechanical Systems (MEMS) sensors, in particular to a Fabry-Perot optical MEMS acceleration sensor with low lateral sensitivity.

Background

The MEMS acceleration sensor gradually replaces the traditional mechanical acceleration sensor due to the advantages of high precision, small volume, low power consumption, easy mass production and the like, and is widely applied to the fields of earthquake monitoring, national defense safety, resource exploration, industrial automation, electronic consumer goods and the like.

Fabry-perot cavity is an optical interference structure composed of two parallel mirrors with certain reflectivity, which is often used as the core photosensitive and adjusting part of devices such as spectrometer, optical filter and laser resonant cavity. With the development of the MEMS technology and the integrated optical technology, people integrate the fabry-perot cavity and the spring mass structure into a whole to manufacture an optical MEMS acceleration sensor. Because the optical interference detection mode is adopted, the acceleration sensor has the characteristics of high detection precision, high sensitivity and strong electromagnetic interference resistance. However, at present, there are few patents disclosing related to fabry-perot optical MEMS acceleration sensors in China, and the MEMS fabry-perot optical acceleration sensors reported in the related documents have the disadvantages of low resolution, poor portability and practicability, high lateral sensitivity, poor temperature stability, and the like.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the low-lateral-sensitivity Fabry-Perot optical MEMS acceleration sensor which has the advantages of high detection precision, low lateral sensitivity, good temperature stability, high portability and practicability and the like.

In order to achieve the purpose, the invention adopts the technical scheme that:

a Fabry-Perot optical MEMS acceleration sensor with low lateral sensitivity comprises a base 7, wherein the upper surface of the base 7 is connected with a sensor shell 1 to form a cavity, a semiconductor refrigerating sheet 5 is connected on the base 7 in the cavity, a second support 3 is connected above the semiconductor refrigerating sheet 5, a laser diode 8 is connected inside the second support 3, the upper surface of the semiconductor refrigerating sheet 5 is bonded with the laser diode 8, a sensitive chip 9 is connected above the second support 3, a first support 2 is connected above the sensitive chip 9, a circuit board 10 is connected above the first support 2, a photoelectric detection chip 11, the semiconductor refrigerating sheet 5 and the sensitive chip 9 are connected on the lower surface of the circuit board 10, the circuit board 10 is electrically connected with the first pin group 4, the laser diode 8 is electrically connected with the second pin group 6, and the first pin group 4 and the second pin group 6 penetrate through the base 7 and extend out of the cavity.

The sensitive chip 9 is an MEMS Fabry-Perot optical spring mass structure, a Fabry-Perot cavity is formed by the movable mirror 9-1, the cavity 9-2 and the fixed mirror 9-3, when single-frequency laser emitted by the laser diode 8 enters the sensitive chip 9, multiple reflection and transmission can occur in the cavity, and interference light is finally output; when the sensor is acted by longitudinal acceleration, the movable mirror 9-1 vibrates up and down to cause the cavity length of the Fabry-Perot cavity, namely the distance between the movable mirror 9-1 and the fixed mirror 9-3 changes, so that the interference phase changes, and the magnitude of the acceleration is obtained by demodulating the variation of the phase; the upper and lower surfaces of the movable mirror 9-1 and the fixed mirror 9-3 are respectively processed with an infrared light antireflection film composed of silicon nitride and an infrared light antireflection film composed of silicon oxide and germanium, so that the sensitive chip 9 has high optical fineness; in addition, gold electrodes are processed on the upper surfaces of the movable mirror 9-1 and the fixed mirror 9-3 and used for adjusting the cavity length of the sensitive chip 9 and improving the sensitivity of the body sensor.

The movable mirror 9-1 adopts a split spring mass structure and comprises a frame 9-1-1, a transverse acceleration isolation mass block 9-1-2, a spring 9-1-3 and a central mass block 9-1-4, wherein the frame 9-1-1 is connected with the outer side of the transverse acceleration isolation mass block 9-1-2 through the spring 9-1-3, the inner side of the transverse acceleration isolation mass block 9-1-2 is connected with the central mass block 9-1-4 through the spring 9-1-3, the transverse acceleration isolation mass block 9-1-2 is of a split block structure and is formed by four L-shaped mass block blocks which are distributed in central symmetry; the working direction of the movable mirror 9-1, namely the acceleration sensitive direction, is the Z-axis direction (vertical to the paper surface), when the movable mirror is acted by the transverse acceleration (parallel to the paper surface), the transverse acceleration isolates the mass block 9-1-2 from twisting, and the central mass block 9-1-4 is always kept in a horizontal state, so that the transverse sensitivity of the sensor is reduced.

The semiconductor refrigerating sheet 5 refrigerates the upper surface and releases heat on the lower surface when in work; the semiconductor refrigeration piece 5 is of a cuboid structure, a through hole is formed in the center of the semiconductor refrigeration piece and used for placing the laser diode 8, and a temperature closed-loop control system is formed through the thermistor and the temperature control chip, so that the laser diode 8 is cooled due to heating caused by work, the wavelength output of the laser diode 8 is kept stable, the detection noise of the sensor is reduced, and the measurement accuracy of the sensor is improved.

The sensor shell 1, the first support 2, the second support 3 and the base 7 are used jointly, the semiconductor refrigerating sheet 5, the laser diode 8, the sensitive chip 9 and the photoelectric detection chip 11 are fixedly integrated into a whole, and the portability and the practicability of the sensor are improved.

The laser diode 8 is a Distributed Feedback (DFB) laser diode and is integrated with a converging lens.

The lower surface of the second bracket 3 is provided with a groove with the same shape and specification as the laser diode 8.

The first pin group 4 comprises 8 wiring pins which respectively provide wiring points for the semiconductor refrigerating sheet 5, the sensitive chip 9 and the circuit board 10; the second pin group 6 comprises 4 wiring pins which are the power-on wiring points of the laser diode 8.

The shell 1 and the base 7 are made of aluminum.

The invention has the beneficial effects that: the invention adopts a Fabry-Perot interference optical detection mode and combines a split type spring mass structure, so that the invention has the advantages of high detection precision and low transverse sensitivity; meanwhile, a temperature closed-loop control system composed of semiconductor refrigerating chips is arranged in the temperature control system, and the temperature control system is packaged by combining an aluminum sensor, so that the temperature control system has the advantages of good temperature stability, portability and strong practicability.

Drawings

Fig. 1 is a cross-sectional view of the overall structure of the present invention.

Fig. 2 is a cross-sectional view of the sensor chip 9 of the present invention.

FIG. 3 is a schematic three-dimensional structure of movable mirror 9-1 according to the present invention.

Fig. 4 is a cross-sectional view of the combined clamp composed of the first frame 2, the second frame 3 and the semiconductor chilling plate 5.

Detailed Description

The present invention is described in further detail below with reference to the accompanying drawings.

Referring to fig. 1, the fabry-perot optical MEMS acceleration sensor with low lateral sensitivity includes a base 7, the upper surface of the base 7 is connected with a sensor housing 1 to form a cavity, the base 7 is a bottom layer structure of the fabry-perot optical MEMS acceleration sensor and plays roles of bearing the whole sensor and dissipating heat, and the sensor housing 1 plays a role of isolating internal parts of the sensor from an external environment and simultaneously plays a part of a role of dissipating heat; the upper surface of a base 7 in the cavity is bonded with a semiconductor refrigerating sheet 5 by using heat conducting glue, the upper surface of the semiconductor refrigerating sheet 5 refrigerates and the lower surface of the semiconductor refrigerating sheet 5 heats when in work, and the heat productivity of the lower surface of the semiconductor refrigerating sheet is transferred to the base 7 through the heat conducting glue and further dissipated to the outside; a second bracket 3 is connected above the semiconductor refrigerating sheet 5, and a laser diode 8 is connected inside the second bracket 3; the upper surface of the semiconductor refrigeration piece 5 is bonded with the laser diode 8 by utilizing heat-conducting glue, and is combined with the second bracket 3 for use, so that the laser diode 8 is positioned and fixed, and meanwhile, the semiconductor refrigeration piece 5 also plays a role in cooling the laser diode 8; a sensitive chip 9 is connected above the second support 3, a first support 2 is connected above the sensitive chip 9, a circuit board 10 is connected above the first support 2, a photoelectric detection chip 11 is connected on the lower surface of the circuit board 10, and the circuit board 10 and the photoelectric detection chip 11 jointly act to detect the interference light intensity; the upper surface of the first bracket 2 bears a photoelectric detection chip 11 and a circuit board 10, and the lower surface is pressed and fixed with a sensitive chip 9; the semiconductor refrigerating piece 5, the sensitive chip 9, the circuit board 10 and the first pin group 4 are electrically connected, the laser diode 8 and the second pin group 6 are electrically connected, and the first pin group 4 and the second pin group 6 penetrate through the base 7 and extend out of the cavity.

The material of sensor housing 1 is aluminium, and its effect is isolated with the external environment with the inside device of sensor, undertakes partly heat dissipation effect simultaneously.

The lower surface of the second bracket 3 is provided with a groove with the same shape and specification as the laser diode 8 so as to achieve the functions of positioning and fastening the laser diode 8.

The first pin group 4 comprises 8 wiring pins which respectively provide wiring points for the semiconductor refrigerating sheet 5, the sensitive chip 9 and the circuit board 10.

The semiconductor refrigerating sheet 5 refrigerates the upper surface and releases heat on the lower surface when in work. The semiconductor refrigeration piece is of a cuboid structure, a 5mm through hole is formed in the center of the semiconductor refrigeration piece and used for placing the laser diode 8, and a temperature closed-loop control system is formed through the thermistor and the temperature control chip, so that the laser diode 8 is cooled due to heating caused by work, the wavelength output of the laser diode 8 is kept stable, the detection noise of the sensor is reduced, and the measurement accuracy of the sensor is improved.

The second pin group 6 comprises 4 wiring pins which are the power-on wiring points of the laser diode 8.

The base 7 is an aluminum base.

The laser diode 8 is a Distributed Feedback (DFB) laser diode and is integrated with a converging lens; the laser diode 8 provides an interference light source for the sensor, while a phase carrier signal can be provided for a subsequent signal demodulation system by a laser tuning technique.

Referring to fig. 2, the sensitive chip 9 is an MEMS fabry-perot optical spring mass structure, a movable mirror 9-1, a cavity 9-2, and a fixed mirror 9-3 form a fabry-perot cavity, and when a single-frequency laser emitted from a laser diode 8 enters the sensitive chip 9, it is reflected and transmitted many times in the cavity, and finally outputs interference light; when the sensor is acted by longitudinal acceleration, the movable mirror 9-1 vibrates up and down to cause the cavity length of the Fabry-Perot cavity, namely the distance between the movable mirror 9-1 and the fixed mirror 9-3 changes, so that the interference phase changes, and the magnitude of the acceleration is obtained by demodulating the variation of the phase; the movable mirror surface 9-1 is of a split spring mass structure, and the upper surface and the lower surface of the movable mirror surface are respectively plated with an infrared light antireflection film of 190nm silicon nitride and an infrared light antireflection film consisting of 264nm silicon dioxide and 94nm germanium.

The sensitive chip 9 integrates an acceleration sensing inertial spring mass structure and a Fabry-Perot interference cavity into a whole by combining an MEMS technology and an integrated optical technology to form an optical MEMS structure; an infrared light antireflection film and an infrared light antireflection film are respectively deposited on the upper surface and the lower surface of the movable mirror surface 9-1 by a thin film deposition process, and an infrared light antireflection film are respectively deposited on the upper surface and the lower surface of the fixed mirror surface 9-3 by a thin film deposition process, so that the sensitive chip 9 has high optical fineness. In addition, gold electrodes are processed on the upper surfaces of the movable mirror 9-1 and the fixed mirror 9-3 for adjusting the cavity length of the sensitive chip 9, thereby improving the sensitivity of the body sensor.

Referring to fig. 3, the movable mirror 9-1 adopts a split spring mass structure, which comprises a frame 9-1-1, a transverse acceleration isolation mass block 9-1-2, a spring 9-1-3 and a central mass block 9-1-4, wherein the frame 9-1-1 is connected with the outer side of the transverse acceleration isolation mass block 9-1-2 through the spring 9-1-3, the inner side of the transverse acceleration isolation mass block 9-1-2 is connected with the central mass block 9-1-4 through the spring 9-1-3, the transverse acceleration isolation mass block 9-1-2 is a split block structure and is formed by four L-shaped mass blocks which are distributed in a central symmetry manner; the working direction of the movable mirror 9-1, namely the acceleration sensitive direction, is the Z-axis direction (vertical to the paper surface), and when the movable mirror is acted by the transverse acceleration (parallel to the paper surface), the transverse acceleration isolates the mass block 9-1-2 from twisting, so that the central mass block 9-1-4 is ensured to be always kept in a horizontal state, and the transverse sensitivity of the sensor is greatly reduced.

Referring to fig. 4, the first bracket 2, the second bracket 3 and the semiconductor refrigeration sheet 5 are used in combination to play a role in positioning and fastening the laser diode 8, the sensitive chip 9, the circuit board 10 and the photoelectric detection chip 11; first support 2 and second support 3 all adopt 3D printing technology processing to make.

Sensor housing 1, first support 2, second support 3 and base 7 jointly use, with semiconductor refrigeration piece 5, laser diode 8, sensitive chip 9 and photoelectric detection chip 11 fixed integration in an organic whole, greatly improved the portable practicality of sensor.

The circuit board 10 and the photoelectric detection chip 11 are bonded together through conductive silver paste and used for detecting interference signals.

The working principle of the invention is as follows: the invention discloses a Fabry-Perot optical MEMS acceleration sensor with low lateral sensitivity, which comprises core components of a laser diode 8, a sensitive chip 9, a photoelectric detection chip 11 and a semiconductor refrigeration piece 5, wherein the laser diode 8 provides a light source for Fabry-Perot interference, the sensitive chip 9 is an acceleration sensing component, the photoelectric detection chip 11 is an interference light intensity component for detecting information with acceleration modulation, and the semiconductor refrigeration piece 5 is a temperature control component. The sensitive chip 9 is a fabry-perot interference cavity formed by the movable mirror 9-1, the cavity 9-2 and the fixed mirror 9-3, when single-frequency laser emitted by the laser diode 8 enters the sensitive chip 9, the single-frequency laser is reflected and transmitted for many times in the cavity, and finally interference light is output and enters the photoelectric detection chip 11 for detection. When the sensor is subjected to the action of longitudinal acceleration, the inertial mass block of the sensor can vibrate up and down to cause the cavity length of the Fabry-Perot cavity, namely the distance between the movable mirror surface 9-1 and the fixed mirror surface 9-3 changes, so that the phase of interference light changes, and the magnitude of the acceleration can be obtained by demodulating the variation of the phase; the refrigerating surface of the semiconductor refrigerating chip 5 is attached below the laser diode 8, and a temperature closed-loop control system is formed through the corresponding temperature control chip and the thermistor, so that the temperature of the laser diode 8 is kept constant, and the laser emitted by the laser diode 8 is kept stable.