Silicon resonance pressure sensor with on-chip stress change detection structure
By introducing a reference resonator and a temperature-sensing resonator into the silicon resonant pressure sensor, stress changes and temperature drift are detected and compensated, solving the accuracy drift problem caused by residual stress and achieving long-term measurement accuracy stability and reliability.
Patent Information
- Application Number
- CN202511146005.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-15
- Publication Date
- 2025-11-18
AI Technical Summary
The residual stress introduced during the manufacturing process of existing silicon resonant pressure sensors is released over time, causing changes in the stress level of the sensitive structure, which in turn affects the sensor's accuracy and long-term measurement accuracy.
Design a silicon resonant pressure sensor with on-chip stress change detection structure. By setting a reference resonator to detect on-chip stress changes and combining it with a temperature-sensing resonator for temperature compensation, online self-correction is achieved.
This achieves long-term measurement accuracy maintenance of the sensor, reduces the number of recalibrations required, lowers usage costs, and improves the reliability and stability of the sensor.
Smart Images
Figure CN120970855A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of MEMS pressure sensors, in particular to a silicon resonant pressure sensor with on-chip stress variation detection structure. BACKGROUND
[0002] Silicon resonant pressure sensors have been widely used in various fields such as aerospace, industrial control, and meteorological measurement due to their high measurement accuracy, good long-term stability, and easy integration with IC. In the field of aerospace, accurate pressure measurement is crucial for flight control, attitude adjustment, and engine performance monitoring. In industrial control, pressure sensors can be used to monitor various pressure parameters in the production process to ensure stability and safety. In meteorological measurement, accurate pressure data can help improve weather forecasting accuracy.
[0003] However, silicon resonant pressure chips need to go through multiple bonding processes during manufacturing, and need to be pasted and soldered during packaging. These processes inevitably introduce stress into the chip. Although silicon resonant pressure sensors have relatively higher long-term stability due to their unique sensing mechanism, they still face the same challenges as other types of pressure sensors. The residual stress introduced during the manufacturing process will slowly release over time, and as the stress releases, the stress level of the sensitive structure will change, causing the sensor accuracy to drift. This accuracy drift can seriously affect the measurement accuracy of the sensor during long-term use, increasing the maintenance cost and use risk of the equipment. For example, in the field of aerospace, it may cause the control system of the aircraft to misjudge, affecting flight safety. SUMMARY
[0004] To address the above deficiencies of the prior art, the present application aims to solve the problem of existing silicon resonant pressure sensors that the stress level of the sensitive structure changes due to the release of residual stress introduced during the manufacturing process over time, which in turn causes the sensor accuracy to drift. A silicon resonant pressure sensor with on-chip stress variation detection structure is proposed, which detects the on-chip stress variation and performs online compensation and self-correction, ensuring that the sensor maintains long-term measurement accuracy, and significantly reduces the number of field calibration.
[0005] In order to achieve the above-mentioned purposes, the technical scheme adopted by the present application is to provide a silicon resonant pressure sensor with a structure for detecting stress changes on a chip, which comprises an SOI silicon substrate layer, the upper end surface of the SOI silicon substrate layer is provided with a pressure measuring resonator and a reference resonator, and a sensitive diaphragm is arranged below each of the pressure measuring resonator and the reference resonator; a separation layer is arranged on the lower end surface of the upper end surface of the SOI silicon substrate layer, an air passage is arranged in the separation layer, the top end of the air passage is located directly below the pressure measuring resonator and is in communication with the sensitive diaphragm below the pressure measuring resonator, and the bottom end of the air passage is in communication with the external pressure environment through the lower end surface of the separation layer. The reference resonator is used to measure the stress state changes on the chip.
[0006] The basic principle of the silicon resonant pressure sensor with a structure for detecting stress changes on a chip is that the SOI silicon substrate layer has good electrical and mechanical properties and can provide stable structural support for the sensor; the reference resonator is a key component for detecting stress changes, the reference resonator is isolated from the external pressure environment and is only sensitive to stress state changes, thereby realizing the function of detecting the stress state on the chip, sensitively sensing the changes in the stress on the chip, and reflecting the changes through frequency changes; the pressure information output by the pressure measuring resonator is transmitted to the back-end software or system, the back-end software or system performs online self-correction according to the changes in the stress on the chip sensed by the reference resonator, and finally accurate pressure data is obtained.
[0007] Further, the pressure measuring resonator and the reference resonator have the same structure, the sensitive diaphragms below the pressure measuring resonator and the reference resonator are uniform in size and thickness, and the pressure measuring resonator and the reference resonator are symmetrically arranged on the upper end surface of the SOI silicon substrate layer.
[0008] The beneficial effects of the above technical scheme are that the structural consistency of the pressure measuring resonator and the reference resonator ensures that the reference resonator can accurately represent the stress state changes of the pressure measuring resonator, because the two have the same structure and their response characteristics are similar under the same stress environment, so the frequency changes of the reference resonator can reflect the frequency change trend of the pressure measuring resonator due to stress changes. The above technical scheme is an important basis for the present application to realize accurate stress detection and compensation.
[0009] Further, the upper end surface of the SOI silicon substrate layer is further provided with a temperature measuring resonator, the temperature measuring resonator is located between the pressure measuring resonator and the reference resonator, no sensitive diaphragm is arranged below the temperature measuring resonator and the temperature measuring resonator is isolated from the external pressure environment.
[0010] The beneficial effects of the above technical solutions are that: there is no sensitive diaphragm below the temperature measuring resonator, and the temperature measuring resonator is not sensitive to pressure and stress changes and is mainly used as a temperature sensor. In a variable temperature environment, the outputs of the pressure measuring resonator and the reference resonator will drift, and the temperature measuring resonator can compensate for this temperature drift and decouple the temperature as an environmental factor. By detecting the change in the natural frequency of the reference resonator after temperature decoupling, the on-chip stress change can be accurately characterized, and the back-end software or system can be used for online compensation and self-correction. The temperature interference can be eliminated, and the accuracy of the measurement data is ensured.
[0011] Further, the pressure measuring resonator, the reference resonator, the sensitive diaphragm and the temperature measuring resonator are formed by MEMS processing technology.
[0012] Further, the calculation formula of the pressure output by the silicon resonant pressure sensor is:
[0013]
[0014]
[0015] wherein, P is the pressure value output by the pressure measuring resonator; P is the pressure offset affected by the stress; f is the output frequency of the pressure measuring resonator affected by temperature and pressure; f is the output frequency of the temperature measuring resonator affected by temperature; f is the output frequency of the reference resonator affected by temperature and pressure.
[0016] Further, the isolation layer is made of a material similar to the thermal expansion coefficient of silicon, and the air hole is made by laser drilling technology. After aligning the air hole with the pressure measuring resonator, the isolation layer and the SOI silicon substrate layer are connected together by using the bonding technology; the reference resonator is isolated from the external pressure environment and is only sensitive to the stress state change.
[0017] Compared with the existing silicon resonant pressure sensor box wall, the beneficial effects of the present application are: 1. The silicon resonant pressure sensor with an on-chip stress change detection structure of the present application comprises a group of reference resonators which are symmetrical and pressure-immune and have the same structural characteristics as the pressure measuring resonator, and a temperature measuring resonator is used to compensate the temperature of the pressure measuring resonator and the reference resonator. This innovative design enables the sensor to accurately detect the on-chip stress change and effectively separate the influence of temperature on the measurement.
[0018] 2、The silicon resonant pressure sensor with the on-chip stress change detection structure can use the frequency change amount of the reference resonator after temperature decoupling to compensate and self-correct the drift amount of the pressure measuring resonator affected by stress online.
[0019] 3、The silicon resonant pressure sensor with the on-chip stress change detection structure can break through the inherent time drift problem limit, and has the ability to maintain the measurement accuracy level for a long time. BRIEF DESCRIPTION OF DRAWINGS
[0020] Fig. 1 It is a top view structural schematic diagram of a silicon resonant pressure sensor with an on-chip stress change detection structure.
[0021] Fig. 2 It is a schematic diagram of a front view structural schematic diagram of a silicon resonant pressure sensor with an on-chip stress change detection structure.
[0022] Fig. 3 It is a quarter cross-sectional structural schematic diagram of a silicon resonant pressure sensor with an on-chip stress change detection structure.
[0023] 1, SOI silicon substrate layer; 2, pressure measuring resonator; 3, reference resonator; 4, sensitive diaphragm; 5, isolation layer; 6, air hole; 7, temperature measuring resonator. DETAILED DESCRIPTION
[0024] The specific embodiments of the present application are described below to facilitate the understanding of the present application by those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and for those skilled in the art, it is obvious that various changes are within the spirit and scope of the present application defined and determined by the appended claims, and all the inventions utilizing the concept of the present application are within the scope of protection.
[0025] REFERENCE Figs. 1-3As shown, a silicon resonant pressure sensor with a diaphragm on-chip stress variation detection structure includes an SOI silicon substrate layer 1, a pressure measurement resonator 2, a reference resonator 3, a sensitive diaphragm 4 and a temperature measurement resonator 7 are processed on the SOI silicon substrate layer 1 by MEMS processing technology. Among them, the pressure measurement resonator 2 and the reference resonator 3 are provided with a sensitive diaphragm 4 below. The SOI silicon substrate layer 1 has good electrical and mechanical properties, which can provide stable structural support for the sensor.
[0026] Specifically, the lower end surface of the upper end surface of the SOI silicon substrate layer 1 is provided with an isolation layer 5, and the isolation layer 5 is provided with an air hole 6, the top end of the air hole 6 is located directly below the pressure measurement resonator 2 and is in communication with the sensitive diaphragm 4 below the pressure measurement resonator 2, and the bottom end of the air hole 6 is connected with the lower end surface of the isolation layer 5 and is in communication with the external pressure environment. The isolation layer 5 is made of a material with a similar thermal expansion coefficient to silicon, and the air hole 6 is made by laser drilling technology. After aligning the air hole 6 with the pressure measurement resonator 2, the isolation layer 5 and the SOI silicon substrate layer are connected together by using the bonding technology; the reference resonator 3 is isolated from the external pressure environment and is only sensitive to stress state changes.
[0027] The working principle of the silicon resonant pressure sensor is as follows: the reference resonator 3 is a key component for detecting stress changes, the reference resonator 3 is isolated from the external pressure environment and is only sensitive to stress state changes, thereby realizing the on-chip stress state detection function, which can sensitively sense the change of the on-chip stress and reflect it through the frequency change; the temperature measurement resonator 7 has no sensitive diaphragm 4 below and is not sensitive to pressure and stress changes, and is mainly used as a temperature sensor. In a variable temperature environment, the outputs of the pressure measurement resonator 2 and the reference resonator 3 will drift, and the temperature measurement resonator 7 can compensate for this temperature drift and decouple the temperature as an environmental factor. By detecting the natural frequency change of the reference resonator 3 after temperature decoupling, the on-chip stress variation can be accurately characterized, which can be used for online compensation and self-correction by the backend software or system, and the temperature interference can be eliminated, so that accurate pressure data can be obtained, and the accuracy of the measurement data is guaranteed.
[0028] Further, the pressure measuring resonator 2 and the reference resonator 3 are structurally identical, the sensitive diaphragms 4 below the two are uniform in size and thickness, and the pressure measuring resonator 2 and the reference resonator 3 are symmetrically arranged on the upper end surface of the SOI silicon substrate layer 1. The temperature measuring resonator 7 is located between the pressure measuring resonator 2 and the reference resonator 3. The structural consistency of the pressure measuring resonator 2 and the reference resonator 3 ensures that the reference resonator 3 can accurately characterize the stress state change of the pressure measuring resonator 2, because the two have the same structure and similar response characteristics under the same stress environment, so the frequency change of the reference resonator 3 can reflect the frequency change trend of the pressure measuring resonator 2 due to stress change. The above technical solution is an important basis for the present application to realize accurate stress detection and compensation.
[0029] Further, the calculation formula of the pressure output by the silicon resonant pressure sensor is:
[0030]
[0031]
[0032] wherein, P is the pressure value output by the pressure measuring resonator 2; P is the pressure offset affected by stress; f is the output frequency of the pressure measuring resonator 2 after being affected by temperature and pressure; f is the output frequency of the temperature measuring resonator 7 after being affected by temperature; f is the output frequency of the reference resonator 3 after being affected by temperature and pressure.
[0033] In summary, the silicon resonant pressure sensor with an on-chip stress change detection structure of the present application can accurately detect the on-chip stress change and effectively separate the influence of temperature factors on measurement by arranging a group of reference resonators 3 which are structurally consistent with the pressure measuring resonator 2, symmetrically distributed and immune to pressure, and using a temperature measuring resonator 7 to perform temperature compensation on the pressure measuring resonator 2 and the reference resonator 3. This innovative design enables the sensor to accurately detect on-chip stress changes and effectively separate the influence of temperature factors on measurement. It also enables the pressure sensor to break through the inherent time drift problem and has the ability to maintain long-term measurement accuracy. Traditional sensors need to be calibrated regularly due to time drift, increasing the cost and difficulty of maintenance. The sensor of the present application significantly reduces the frequency of field calibration, reduces the use cost, improves the reliability and stability of the sensor, and has a wide application prospect in the fields of aerospace, industrial control and other fields with high requirements for pressure measurement accuracy and long-term stability.
Claims
1. A silicon resonant pressure sensor with on-chip stress variation detection structure, characterized by, The SOI silicon substrate layer is provided with a pressure measuring resonator and a reference resonator on the upper end surface, and each of the pressure measuring resonator and the reference resonator is provided with a sensitive diaphragm below; a separation layer is arranged on the lower end surface of the upper end surface of the SOI silicon substrate layer, and the separation layer is provided with an air hole, the top end of the air hole is located directly below the pressure measuring resonator and communicates with the sensitive diaphragm below the pressure measuring resonator, and the bottom end of the air hole is connected with the lower end surface of the separation layer and communicates with the external pressure environment.
2. The silicon resonant pressure sensor with on-chip stress variation detection structure according to claim 1, characterized in that, The pressure measuring resonator and the reference resonator are of the same structure, the sensitive diaphragms below the pressure measuring resonator and the reference resonator are of the same size and thickness, and the pressure measuring resonator and the reference resonator are symmetrically arranged on the upper end surface of the SOI silicon substrate layer.
3. The silicon resonant pressure sensor with on-chip stress variation detection structure according to claim 2, characterized in that, The upper end surface of the SOI silicon substrate layer is further provided with a temperature measuring resonator, the temperature measuring resonator is located between the pressure measuring resonator and the reference resonator, no sensitive diaphragm is arranged below the temperature measuring resonator and the temperature measuring resonator is isolated from the external pressure environment.
4. The silicon resonant pressure sensor with on-chip stress variation detection structure according to claim 3, characterized in that, The pressure measuring resonator, the reference resonator, the sensitive diaphragm and the temperature measuring resonator are formed by MEMS processing technology.
5. The silicon resonant pressure sensor with on-chip stress variation detection structure according to claim 3, wherein, The calculation formula of the pressure output by the silicon resonant pressure sensor is: wherein is the pressure value output by the pressure measurement resonator; is the pressure offset affected by the stress; is the output frequency of the pressure measurement resonator affected by the temperature and the pressure; is the output frequency of the temperature measurement resonator affected by the temperature; is the output frequency of the reference resonator affected by the temperature and the pressure.
6. The silicon resonant pressure sensor with on-chip stress variation detection structure according to claim 1, wherein, The separation layer is made of a material similar to the thermal expansion coefficient of silicon, the air hole is made by laser drilling technology, the air hole is aligned with the pressure measuring resonator, the separation layer and the SOI silicon substrate layer are connected together by using the bonding technology, the reference resonator is isolated from the external pressure environment and is only sensitive to the stress state change.