A MEMS silicon pressure sensor chip with PT resistance and a sensor

Abstract

The application discloses a MEMS silicon pressure sensor chip with a PT resistance and a sensor, and the chip comprises a pressure-sensitive diaphragm; wherein the pressure-sensitive diaphragm is etched on the front surface to be ring-shaped and uniformly arranged with 2N discontinuous concave regions; the adjacent gaps of the 2N discontinuous concave regions form N straight beams; the middle region surrounded by the 2N discontinuous concave regions forms a center circular island; N is a positive integer; four pressure-sensitive resistances are symmetrically arranged on the same straight beam; and the center circular island is integrated with a PT resistance. The application adopts the mode of integrating the PT resistance on the front surface structure of the chip, and the temperature response is real-time and rapid, and the result is real; the temperature compensation problem of the sensor under the condition of rapid temperature change can be solved, and the performance of the MEMS silicon pressure sensor is improved.

Description

Technical Field

[0001] This invention relates to the field of sensor chip technology, and in particular to a MEMS silicon pressure sensor chip and sensor with a PT resistor. Background Technology

[0002] MEMS silicon pressure sensors are silicon cup-shaped structures fabricated from single-crystal silicon using MEMS processing technology, as referenced. Figure 1 As shown, four semiconductor resistors of equal value are formed on the front side of the thin film through doping or ion implantation. The four varistors are connected by metal wires to form a Wheatstone bridge circuit.

[0003] When external pressure is applied, the stress in the piezoresistive region changes, causing a change in resistance and resulting in an unbalanced output voltage signal in the bridge circuit. However, due to the inherent properties of semiconductor materials, the sensor's output is affected by temperature changes, leading to temperature drift that severely impacts the sensor's measurement accuracy.

[0004] Traditional temperature compensation schemes include hardware and software compensation. Hardware compensation is often difficult to apply in applications requiring high accuracy, and it is also difficult to debug and lacks flexibility. Software compensation uses compensation algorithms and mathematical methods based on calibration data to correct for sensor zero-point drift, sensitivity drift, and nonlinearity. It requires an external temperature sensor connected to the sensor processing circuit to detect the chip's operating environment temperature. However, in environments with rapid temperature changes, traditional external temperature sensors exhibit significant lag in their temperature response, and their positional deviations prevent them from accurately reflecting the chip's true temperature. Summary of the Invention

[0005] In view of this, the purpose of this invention is to solve the temperature compensation problem of sensors under rapid temperature changes and improve the performance of MEMS silicon pressure sensors; and to provide a MEMS silicon pressure sensor chip and sensor with a PT resistor.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a MEMS silicon pressure sensor chip with a PT resistor; comprising: a pressure-sensitive diaphragm;

[0008] Among them, 2N discontinuous recesses are etched in a ring-shaped uniform arrangement on the front side of the pressure-sensitive diaphragm; the gaps between the adjacent 2N discontinuous recesses form N straight beams; the central area enclosed by the 2N discontinuous recesses forms a central circular island; N is a positive integer;

[0009] Four varistors are symmetrically arranged on the same straight beam;

[0010] The central circular island integrates a PT resistor.

[0011] Furthermore, the four varistors are divided into two groups, with the first group consisting of longitudinal resistors R1 and R3, and the second group consisting of transverse resistors R2 and R4; the resistors in the first group and the resistors in the second group are mirror images of each other.

[0012] Furthermore, the four varistors are arranged along the 110 crystal direction.

[0013] Furthermore, the varistor has a bent structure.

[0014] Furthermore, the varistor includes: two varistor strips and a heavily doped connecting strip; each end of the heavily doped connecting strip is respectively connected to one end of a varistor strip.

[0015] The other end of the varistor strip is connected to the metal lead via a heavily doped connecting block.

[0016] Furthermore, the PT resistor has an arc-shaped grid wire structure.

[0017] Furthermore, the straight beam is a stress concentration region, as determined by ANSYS finite element simulation.

[0018] Furthermore, when N is greater than 1, the metal leads of the PT resistor are arranged on the first straight beam, and the varistor is arranged on the second straight beam.

[0019] Furthermore, the first and second straight beams are perpendicular to each other.

[0020] Secondly, embodiments of the present invention also provide a sensor, including any of the MEMS silicon pressure sensor chips with PT resistors described in the first aspect above.

[0021] The advantages and effects of this invention are:

[0022] 1. In this invention, a recessed area is etched on the front side of the pressure-sensitive diaphragm; a straight beam is formed by the gaps between adjacent recessed areas; a central circular island is formed in the middle area enclosed by the recessed areas, creating a beam-island structure for the circular diaphragm. Positive and negative stress concentrations occur near the edges of the diaphragm and islands, respectively. By placing pressure-sensitive resistors at these stress concentration points, a sufficiently high output from the sensor chip is ensured. This reduces the chip size without affecting linearity, while utilizing the high stress concentration areas on the beam structure to improve the sensor's output sensitivity. The application of the beam-island structure achieves localized reinforcement of the diaphragm, significantly reducing its deflection and thus nonlinear errors; furthermore, the linear bending stress is concentrated on the narrow beam, ensuring high sensor sensitivity.

[0023] 2. This invention optimizes the design structure size while ensuring the symmetrical arrangement of the varistor. By combining the high stress concentration range on the chip beam, the number of varistor segments and their specific dimensions are designed to maximize the utilization of the stress concentration area, thereby maximizing the output of the sensor chip.

[0024] 3. This invention integrates a PT resistor on the front island structure of a beam-membrane island structure chip. When the chip is subjected to load, the diaphragm deforms, and the island structure increases the local stiffness of the diaphragm, resulting in less bending deformation of the PT resistor integrated on the front island. By optimizing the arrangement of the platinum resistance thermometer and using an arc-shaped grid structure, the longitudinal strain of the PT resistor can be effectively reduced when the diaphragm is under load, thus ensuring that the output of the PT resistor is less affected by the diaphragm deformation and can accurately detect temperature changes. Furthermore, since the PT resistor is integrated on the chip body, it can accurately reflect the real-time temperature of the sensor chip, ensuring the accuracy of subsequent temperature compensation input data. Attached Figure Description

[0025] Figure 1 A schematic diagram of a Wheatstone bridge in the prior art;

[0026] Figure 2 This is a schematic diagram of the MEMS silicon pressure sensor chip structure with a PT resistor according to the present invention.

[0027] Figure 3 This is a schematic diagram of the varistor structure of the present invention;

[0028] In the diagram: 1. Metal lead; 2. Varistor; 3. Recessed area; 4. Central circular island; 5. Straight beam; 6. PT resistor; 7. Stress concentration area; 8. Varistor diaphragm; 9. Heavily doped connecting strip; 10. Varistor strip; 11. Heavily doped connecting block. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1

[0031] Reference Figure 2 As shown, the present invention provides a MEMS silicon pressure sensor chip with a PT resistor, comprising: a pressure-sensitive diaphragm 8;

[0032] In this process, 2N discontinuous recesses 3 are etched in a ring-shaped, uniform arrangement on the front side of the pressure-sensitive diaphragm 8; the gaps between adjacent recesses 3 form N straight beams 5; the central area enclosed by the 2N discontinuous recesses 3 forms a central circular island 4; N is a positive integer. For example... Figure 2 In the middle, N=2, there are four discontinuous concave regions 3, and adjacent gaps form two straight beams 5.

[0033] In this embodiment, the etching method can be KOH or TMAH wet etching; the pressure-sensitive film is both the substrate of the pressure-sensitive resistor and the bearer of the applied stress, so it is the core part of the pressure sensing element; the pressure-sensitive film can be made of SOI silicon wafer, with an isolation layer and a stabilization layer deposited sequentially on the surface, and the isolation layer is made by thermal oxygen growth or chemical vapor deposition; this embodiment does not limit the scope of the invention.

[0034] Four varistors 2 are symmetrically arranged on the same straight beam 5; the varistors are P-type polycrystalline silicon nanofilm resistors, and a PT resistor 6 is integrated in the central circular island 4.

[0035] In this embodiment, the four pressure-sensitive resistors 2 are divided into two groups, where the first group consists of longitudinal resistors R1 and R3; the second group consists of transverse resistors R2 and R4; the resistances of the first group and the second group are mirror images of each other; when an external load is applied to the pressure-sensitive diaphragm, the resistance values ​​of resistors R1 and R3 increase, while the resistance values ​​of resistors R2 and R4 decrease.

[0036] In this embodiment, the region of the straight beam 5 near the edge of the pressure-sensitive diaphragm 8 has the largest positive longitudinal and transverse stress difference, while the region of the straight beam 5 near the central circular island 4 has a negative longitudinal and transverse stress difference, thus ensuring the high sensitivity of the pressure-sensitive chip. The metal leads 1 arrange the four pressure-sensitive resistors 2 into a fully open-loop Wheatstone bridge circuit structure, establishing an electrical connection with the sensor circuit to obtain relevant sensor test information.

[0037] In this embodiment, the four varistors are arranged along the 110 crystal direction. The spatial framework in which atoms are arranged in a regular pattern in a crystal is called a crystal lattice. Crystal direction refers to the directionality of a crystal, specifically including the three indices 110, 011, and 101. The crystal properties are different along different directions of the crystal lattice.

[0038] In this embodiment, the varistor 2 has a bent structure, which can avoid lateral effects at the bend of the varistor strip.

[0039] Reference Figure 3As shown, the varistor 2 includes two varistor strips 10 and a heavily doped connecting strip 9. Each end of the heavily doped connecting strip 9 is connected to one end of a varistor strip 10. The heavy doping method uses P-type heavy doping ion implantation, with the doping source being a boron compound. If N-type heavy doping ion implantation is used, the doping source is a phosphorus or arsenic compound. The other end of the varistor strip 10 is connected to a metal lead via a heavily doped connecting block 11.

[0040] like Figure 2 As shown, PT resistor 6 has an arc-shaped grid wire structure. This effectively avoids changes in the output resistance caused by strain due to deformation of the varistor diaphragm during varistor chip operation, thus ensuring the accuracy of PT resistor temperature testing.

[0041] In this embodiment, the straight beam is a stress concentration area, as determined by ANSYS finite element simulation. When external loads are applied to the pressure-sensitive diaphragm, the stress concentration area appears near the edge of the diaphragm. To maximize the utilization of this stress concentration area, ANSYS provides functions for dragging, extending, rotating, moving, and copying solid model elements when creating a solid model.

[0042] ANSYS programs can directly mesh complex models, avoiding the problems caused by mesh mismatches when users mesh each part separately and then assemble them. Adaptive meshing involves the user instructing the program to automatically generate finite element meshes after generating a solid model with boundary conditions, analyzing and estimating the mesh's discretization error, redefining the mesh size, and re-analyzing and estimating the mesh's discretization error until the error is lower than the user-defined value or the user-defined number of solutions is reached.

[0043] In this embodiment, when N is greater than 1, the metal lead 1 of the PT resistor is arranged on the first straight beam, and the varistor 2 is arranged on the second straight beam. The first and second straight beams are perpendicular to each other; that is, they can be axes of each other to satisfy symmetry. This symmetry can minimize the degree of performance interference caused by objective factors. For example, the heating of the resistors will have a similar effect on the temperature diffusion of the surrounding area due to the similar structure.

[0044] Example 2

[0045] Based on the same inventive concept, the present invention also provides a sensor, including the MEMS silicon pressure sensor chip with PT resistor of the above embodiment 1, a silicon substrate, a glass substrate and a bonding pad;

[0046] A silicon substrate is bonded to a glass substrate, and a vacuum chamber is formed on the silicon substrate; the glass substrate and the silicon substrate are anoly bonded, and the silicon substrate is made of SOI material;

[0047] The glass substrate and the silicon substrate are bonded by anodic bonding. When heated to a high temperature, the sodium ions in the glass become mobile. Driven by a high voltage electric field, the sodium ions leave the contact surface. Covalent bonds are formed between the Si in the glass substrate and the silicon substrate near the contact surface. Thus, a tight connection between the glass substrate and the silicon substrate is achieved. Furthermore, the chip is sealed on the glass substrate by bonding, which greatly enhances the vacuum degree and sealing strength of the vacuum chamber.

[0048] The metal leads of the PT resistor and varistor in the chip are connected to solder pads at the bends; the metal leads can be made of copper wire.

[0049] The sensor provided by this invention has a simple structure, high stability and versatility, and has broad application prospects.

[0050] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles disclosed herein.

Claims

1. A MEMS silicon pressure sensor chip with a PT resistance, characterized in that, The MEMS silicon pressure sensor chip with a PT resistor comprises: a pressure-sensitive diaphragm; wherein the pressure-sensitive diaphragm is etched on the front surface to form 2N discontinuous concave regions arranged in a ring shape; the adjacent gaps between the 2N discontinuous concave regions form N straight beams; the intermediate region surrounded by the 2N discontinuous concave regions forms a central circular island; N is a positive integer; the straight beam is a stress concentration area, the area close to the pressure-sensitive diaphragm of the straight beam has a positive longitudinal and transverse stress difference, and the area close to the central circular island of the straight beam has a negative longitudinal and transverse stress difference; four pressure-sensitive resistors are symmetrically arranged on the same straight beam; the pressure-sensitive resistor is a bending structure, and the direction is arranged along the 110 crystal direction; the pressure-sensitive resistor comprises two pressure-sensitive resistor strips and a heavily doped connecting strip; the two ends of the heavily doped connecting strip are respectively connected to one end of each pressure-sensitive resistor strip; the other end of the pressure-sensitive resistor strip is connected to a metal lead through a heavily doped connecting block; the central circular island is integrated with a PT resistor, and the PT resistor is a circular arc type grid wire structure.

2. The MEMS silicon pressure sensor chip with PT resistance according to claim 1, characterized in that, The four pressure-sensitive resistors are divided into two groups, wherein the first group is the longitudinal resistors R1 and R3, and the second group is the transverse resistors R2 and R4; the resistors of the first group are mirror-symmetric to the resistors of the second group.

3. The MEMS silicon pressure sensor chip with PT resistance according to claim 1, characterized in that, When N is greater than 1, the metal lead of the PT resistor is arranged on the first straight beam, and the pressure-sensitive resistor is arranged on the second straight beam.

4. The MEMS silicon pressure sensor chip with PT resistance according to claim 3, characterized in that, The first straight beam and the second straight beam are perpendicular to each other.

5. A sensor characterized by, The MEMS silicon pressure sensor chip with a PT resistor comprises any one of claims 1-4.

Images