An overload-resistant pressure sensor chip based on topology optimization design and a preparation method thereof

Abstract

An overload-resistant pressure sensor chip based on topological optimization design belongs to the technical field of pressure sensors. The overload-resistant pressure sensor chip comprises an n-type monocrystalline silicon element and a glass substrate bonded with the n-type monocrystalline silicon element through an anode, a cavity is formed in the back of the n-type monocrystalline silicon element, and the glass substrate is tightly attached to form a sealed cavity; a diaphragm pressure sensing structure composed of a thin film front structure layer and a thin film layer is arranged on the top wall surface of the sealed cavity, the thin film structure layer is formed by dry etching the front of the n-type monocrystalline silicon element, and the thin film layer is formed by dry etching the cavity after the back of the n-type monocrystalline silicon element. The overload capacity of the pressure sensor is improved by designing the sensitive diaphragm structure layer through topological optimization, the preparation process is simple, no additional overload mechanism is added, it is beneficial to mass production, and the sensitivity can meet the use requirements. The problems of insufficient overload resistance of the existing sensor, unidirectional overload, complex process, and being not conducive to mass production can be solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pressure sensors, and relates to an overload-resistant pressure sensor chip based on topological optimization design and a preparation method thereof. BACKGROUND

[0002] The main function of a piezoresistive pressure sensor is to convert an external pressure signal into an electrical signal for output based on the piezoresistive effect of a semiconductor and the principle of a Wheatstone bridge. The piezoresistive pressure sensor is widely used in the automotive industry, aerospace, biomedicine and other fields due to its good performance, high reliability and low cost. With the continuous development of science and technology, the performance requirements of the piezoresistive pressure sensor are increasingly improved. The overload capacity is another important indicator for measuring the performance of the piezoresistive pressure sensor in addition to the sensitivity and linearity. When the pressure sensor is used in harsh environments such as aerospace, petrochemical industry and ocean science, the sensor often bears an overload higher than its range pressure due to the volatility of the measurement medium. In order to improve the overload capacity of the pressure sensor, it is necessary to propose a stable and reliable overload-resistant pressure sensor chip and a preparation method.

[0003] Research shows that the structure, size and placement of the sensor chip and the piezoresistor have a great influence on the performance of the pressure sensor, so the structural design of the sensor chip has always been one of the key problems. Patent CN 206828029 U discloses a micro-electro-mechanical system pressure sensor chip with a beam membrane mechanism. The patent concentrates stress at the root of the beam by constructing a peninsula resonant beam and a square resonant beam, thereby significantly improving the sensitivity of the sensor. The sensitivity and overload capacity of the pressure sensor are related to the stress size of the piezoresistor region and the value of the maximum stress point, respectively. In order to balance the overload capacity and sensitivity requirements of the chip, the ideal maximum stress point should be located in the piezoresistor region. Although the sensitivity of the sensor in the above patent is greatly improved, the overload capacity is not effectively improved due to the limitation of the thin sensitive diaphragm, the absence of misplacement between the upper and lower cavities, and the presence of stress concentration in the corner area of the beam root. At present, most sensor structures are similar to the invention, which improves the stress in the piezoresistor region by designing different structures to improve the sensitivity of the sensor, but the maximum stress is still distributed in the middle of the edge of the thin film at the top of the silicon pressure sensor cavity. The above maximum stress distribution feature causes the stress value of the maximum stress point to increase rapidly when the external pressure increases, and when the maximum stress value reaches the fracture strength of silicon, the pressure sensor will be damaged and fail. Therefore, scholars try to improve the overload capacity of the pressure sensor through other measures.

[0004] The application patent CN 112345157 A discloses an anti-overload pressure sensor. The application is based on the corresponding fluid mechanics principle, and a pressure buffering structure is added in the pressure guide hole, and a flow channel with a suitable length is added on the pressure buffering structure to buffer the overload pressure, so as to realize the suppression of transient overload pressure and improve the overload capacity of the pressure sensor. The existence of the pressure buffering mechanism of the application increases the overall size of the pressure sensor, and can only detect one-way pressure and cannot realize bidirectional anti-overload. At the same time, limited by the length of the flow channel in the buffering structure, the application can only suppress transient overload pressure, and when the continuous overload pressure is borne, the buffering structure of the application will not work, and the sensor will still be damaged and fail.

[0005] The application patent CN 104215362 A discloses a piezoresistive high overload pressure sensor and a preparation method thereof. The application proposes a glass-silicon-glass three-layer bonding structure, and the upper and lower glass structures serve as limiters. When the overload pressure is borne, the strain film will deform and contact with the glass, thereby resisting the external pressure and improving the overload capacity of the pressure sensor. However, the three-layer structure has a complex process and is difficult to realize the lead wire, which is difficult to meet the needs of mass industrial production.

[0006] In summary, the existing methods for improving the overload capacity of the pressure sensor still have some shortcomings. On the one hand, the structural design method of the existing pressure sensor chip depends on the experience of the designer, and by constructing a stress concentration structure and increasing the stiffness of the island structure, the stress of the pressure-sensitive resistor area is improved while the linearity is balanced. Although the sensitivity and linearity of the sensor are greatly improved, the overload capacity is not effectively improved due to the thin sensitive diaphragm, the absence of misplacement between the upper and lower cavities, and the stress concentration in the corner area of the beam root. On the other hand, by constructing the pressure buffering structure and the membrane box device, the overload mechanism is improved to a certain extent, but it has the shortcomings of only resisting transient overload, the device being too large relative to the pressure sensor, and only realizing one-way anti-overload. In addition, some scholars also propose a glass-silicon-glass three-layer bonding structure stopper, but due to the complex process and extremely high dimensional accuracy, it is difficult to meet the needs of mass industrial production. Therefore, it is a technical problem to be solved by the application to provide a preparation process that is simple, does not additionally add an overload mechanism, and only improves the overload capacity of the pressure sensor by structural design of the sensor chip. The anti-overload pressure sensor chip proposed by the application is based on the topology optimization method to maximize the stiffness as the design target for subtractive manufacturing, and the maximum stress value will slowly increase in the iteration process. When the stress of the pressure-sensitive resistor area meets the sensitivity use requirement, the iteration stops, so the designed sensor chip can greatly improve the overload capacity of the sensor chip. SUMMARY

[0007] In order to improve the overload capacity, overcome the shortcomings of the prior art, the application aims to provide an overload-resistant pressure sensor chip based on topological optimization design and a preparation method thereof, which has a simple preparation process, does not need to additionally add an overload mechanism, and only needs to design the structure of the sensor chip to improve the overload capacity of the pressure sensor, and is easy to mass produce.

[0008] In order to achieve the above-mentioned purposes, the application adopts the following technical scheme:

[0009] An overload-resistant pressure sensor chip based on topological optimization design, which comprises an n-type single crystal silicon element 1 and a glass substrate 2 bonded to the n-type single crystal silicon element 1 by an anode, a cavity is formed in the back of the n-type single crystal silicon element 1, and the n-type single crystal silicon element 1 and the glass substrate 2 are tightly attached to form a sealed cavity; a diaphragm pressure sensing structure is arranged on the top wall of the sealed cavity, and the diaphragm pressure sensing structure comprises a thin film front structure layer and a thin film layer, the thin film front structure layer is formed by dry etching the front of the n-type single crystal silicon element 1, and the thin film layer is formed by dry etching the cavity in the back of the n-type single crystal silicon element 1.

[0010] The thin film front structure layer is composed of a square groove 13, a long beam 3, a ring center short cross beam reinforcing rib 4, and a center short cross beam 5; the square groove 13 is a square outer frame of the thin film front structure layer, and is connected to the roots of the four long beams 3; the long beam 3 is composed of a first long beam 3-1, a second long beam 3-2, a third long beam 3-3, and a fourth long beam 3-4, the four long beams are arranged in a "cross shape", and the roots of the four long beams are respectively provided with a first pressure sensitive resistor strip 7-1, a second pressure sensitive resistor strip 7-2, a third pressure sensitive resistor strip 7-3, and a fourth pressure sensitive resistor strip 7-4, and the pressure sensitive resistor strips 7 are used to convert external pressure signals into voltage signals; the ring center short cross beam reinforcing rib 4 is composed of a first reinforcing rib 4-1, a second reinforcing rib 4-2, a third reinforcing rib 4-3, and a fourth reinforcing rib 4-4, and is arranged between adjacent long beams 3, and the center short cross beam 5 is arranged in the middle of the square space surrounded by the four reinforcing ribs; the center of the center short cross beam 5 is provided with a chamfer; the first pressure sensitive resistor strip 7-1, the second pressure sensitive resistor strip 7-2, the third pressure sensitive resistor strip 7-3, and the fourth pressure sensitive resistor strip 7-4 are connected to form a Wheatstone bridge through metal leads 8 and pads 9.

[0011] The thin film layer is composed of a thin film 6, which is used to support the thin film front structure layer.

[0012] Further, the Wheatstone bridge is specifically: the first pressure sensitive resistor strip 7-1 is connected with the first pad 9-1 and the second pad 9-2 through the first metal lead 8-1 and the second metal lead 8-2 respectively; the second pressure sensitive resistor strip 7-2 is connected with the second pad 9-2 and the third pad 9-3 through the third metal lead 8-3 and the fourth metal lead 8-4 respectively; the third pressure sensitive resistor strip 7-3 is connected with the third pad 9-3 and the fourth pad 9-4 through the fifth metal lead 8-5 and the sixth metal lead 8-6 respectively; the fourth pressure sensitive resistor strip 7-4 is connected with the first pad 9-1 and the fourth pad 9-4 through the seventh metal lead 8-7 and the eighth metal lead 8-8 respectively; the four pads are located at the four top corners of the square groove 13.

[0013] Further, the square groove 13 of the thin film front structure layer has a length of 4mm-5mm.

[0014] Further, the long beam 3, the ring center short cross beam reinforcing rib 4 and the center short cross beam 5 of the thin film front structure layer have the same thickness, which is 100%-200% of the thickness of the thin film layer.

[0015] Further, the long beam 3, the ring center short cross beam reinforcing rib 4 and the center short cross beam 5 of the thin film front structure layer have the same width, which is 200μm.

[0016] Further, the long beam 3 of the thin film front structure layer is provided with a round corner at the root, the round corner has a radius of 100μm-200μm, and the pressure sensitive resistor strip 7 is arranged on the symmetry axis of the long beam 3.

[0017] A design method of an anti-overload pressure sensor chip structure layer based on topological optimization design, the design method comprising the following steps:

[0018] (1) According to the design requirements of the pressure sensor chip, the initial design structure parameters and the design area are selected, the initial design refers to selecting the n-type single crystal silicon element 1 front without long beam 3, ring center short cross beam reinforcing rib 4 and center short cross beam 5 as the basis, and the design area is a square groove 13 area with the same length as the square outer frame of the thin film front structure layer, and the length is also 4mm-5mm;

[0019] (2) Finite element meshing and material analysis are performed on the initial design domain to obtain the load condition and boundary condition of the pressure sensor during work, the design variable is the relative density of each element in the design domain, the constraint condition is that the volume constraint of the material usage ratio is less than or equal to 0.3 and the stress constraint that the global maximum stress is not more than 80Mpa, and the optimization target is to maximize the structural stiffness;

[0020] (3) Topology optimization is performed on the optimization target and design area described in step (2) under a 0.1Mpa pressure working condition to obtain an initial topology optimization configuration of the thin film front structure layer, the initial topology optimization configuration of the thin film front structure layer including a long beam 3 with a complete force transmission path, a ring center short cross beam reinforcing rib 4, a center short cross beam 5, and irregular island structures without a complete force transmission path;

[0021] (4) Unnecessary structural small features, i.e., irregular island structures without a complete force transmission path, are removed from the initial topology optimization configuration, and reconfiguration is performed according to process requirements and in accordance with the initial topology optimization result to obtain a thin film structure layer.

[0022] Further, the square cavity opened on the back of the thin film 6 has a depth of 100% to 200% of the film thickness.

[0023] Further, the square back cavity opened on the back of the thin film 6 has a side length of 100 to 300μm more than the square groove opened on the front, i.e., 4.1mm to 5.3mm.

[0024] Further, the glass substrate 2 has a through hole 12 in the middle, with a hole diameter of 0.5mm to 1mm, and the through hole 12 is used for passing external gas pressure to realize differential pressure measurement.

[0025] A preparation method of an anti-overload pressure sensor chip based on topology optimization design, comprising the following steps:

[0026] Step 1, light etching and ion implantation are performed on the front of the n-type single crystal silicon element 1 to perform boron ion light doping to form a first pressure sensitive resistor strip 7-1, a second pressure sensitive resistor strip 7-2, a third pressure sensitive resistor strip 7-3, and a fourth pressure sensitive resistor strip 7-4, and then annealing is performed;

[0027] Step 2, light etching and ion implantation are performed again on the front of the product obtained in step 1 to perform boron ion heavy doping to form an ohmic contact region 10, and then annealing is performed;

[0028] Step 3, a contact hole 11 is etched on the front of the product obtained in step 2 using dry etching technology;

[0029] Step 4, light etching is performed on the front of the product obtained in step 3 using a metal lead 8 mask, then magnetic sputtering and peeling are performed to form the metal lead 8 and the solder pad 9, and then high-temperature alloying treatment is performed, the metal lead 8 is parallel to the four sides of the square groove 13, and the four solder pads are located at the four corners of the square groove 13;

[0030] Step 5, the product obtained in step 4 is front photoetched, the front of the n-type monocrystalline silicon element 1 is etched using a dry etching technology, a square groove 13, a long beam 3, a ring center short cross beam reinforcing rib 4 and a center short cross beam 5 are obtained;

[0031] Step 6, the back of the n-type monocrystalline silicon element 1 obtained in step 4 is photoetched using a back cavity etching mask plate, and a cavity is formed by etching using a dry etching technology;

[0032] Step 7, the glass substrate 2 is laser drilled to form a through hole 12;

[0033] Step 8, the n-type monocrystalline silicon element 1 prepared in step 7 is anodically bonded with the glass substrate 2 treated in step 6, to obtain an anti-overload pressure sensor chip based on a topological optimization design.

[0034] Compared with the prior art, the anti-overload pressure sensor chip based on the topological optimization design has at least the following beneficial technical effects:

[0035] 1) The anti-overload pressure sensor chip based on the topological optimization design and the preparation method thereof provided by the application, the structure layer of the sensitive diaphragm is designed by topological optimization, and the maximum stiffness is used as a design target for subtractive manufacturing, so that the structure of the designed sensor chip greatly improves the overload capacity of the sensor chip.

[0036] 2) The anti-overload pressure sensor chip based on the topological optimization design and the preparation method thereof provided by the application, the circular corner arranged at the corner area of the structure layer beam plays a role in uniformly dispersing stress concentration, reduces the value of the maximum stress, and greatly improves the overload capacity of the sensor chip.

[0037] 3) The anti-overload pressure sensor chip based on the topological optimization design and the preparation method thereof provided by the application, the dislocation is formed by the square groove with a larger side length arranged on the back of the n-type monocrystalline silicon element than the square structure layer arranged on the front, the extreme value point of the stress at the back cavity is transferred, the value of the maximum stress is reduced, and the overload capacity of the sensor chip is further improved.

[0038] 4) The anti-overload pressure sensor chip based on the topological optimization design and the preparation method thereof provided by the application, the overload capacity of the pressure sensor is improved by the structural design of the sensor chip, the preparation process is simple, no additional overload mechanism is added, and it is conducive to mass production.

[0039] In summary, the technical scheme of the present application is aimed at the problems of insufficient anti-overload capacity of the existing sensor, unidirectional overload, complex process, and being not conducive to mass production, and the pressure sensor chip is designed through topology optimization. Therefore, the technical scheme of the present application solves the problems of insufficient anti-overload capacity of the existing sensor, unidirectional overload, complex process, and being not conducive to mass production, and the sensitivity can meet the use requirements. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a schematic view of the back of the present application;

[0041] Figure 2 is a perspective view of the back of the present application;

[0042] Figure 3 is Figure 2 is a sectional view of the A-A section of the present application;

[0043] Figure 4 is a schematic view of the manufacturing process of the present application.

[0044] In the figure: 1 n-type single crystal silicon element; 2 glass substrate; 3 long beam; 4 ring center short cross beam reinforcing rib; 5 center short cross beam; 6 thin film; 7 pressure sensitive resistor strip; 8 metal lead; 9 solder pad; 10 ohmic contact area; 11 contact hole; 12 through hole; 13 square groove;

[0045] 3-1 first long beam; 3-2 second long beam; 3-3 third long beam; 3-4 fourth long beam;

[0046] 4-1 first reinforcing rib; 4-2 second reinforcing rib; 4-3 third reinforcing rib; 4-4 fourth reinforcing rib;

[0047] 7-1 first pressure sensitive resistor strip; 7-2 second pressure sensitive resistor strip; 7-3 third pressure sensitive resistor strip; 7-4 fourth pressure sensitive resistor strip;

[0048] 8-1 first metal lead; 8-2 second metal lead; 8-3 third metal lead; 8-4 fourth metal lead; 8-5 fifth metal lead; 8-6 sixth metal lead; 8-7 seventh metal lead; 8-8 eighth metal lead;

[0049] 9-1 first solder pad; 9-2 second solder pad; 9-3 third solder pad; 9-4 fourth solder pad. DETAILED DESCRIPTION

[0050] The specific embodiments of the present application are described in detail below in combination with the technical scheme and the drawings.

[0051] In the description of the present application, it needs to be understood that the terms "front", "back", "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0052] In the description of the present application, it needs to be understood that the terms "first", "second" are only for description purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0053] The present application proposes a design method of an anti-overload pressure sensor chip structure layer based on topology optimization, which comprises the following steps:

[0054] A design method of an anti-overload pressure sensor chip structure layer based on topology optimization design, the design method comprises the following steps:

[0055] (1) According to the design requirements of the pressure sensor chip, the initial design structure parameters and the design area are selected, the initial design refers to selecting the n-type single crystal silicon element 1 front surface without long beam 3, ring center short cross beam reinforcing rib 4 and center short cross beam 5, and the design area is a square groove 13 area with the same length as the square outer frame of the thin film 6 front surface structure layer, and the length is also 4mm-5mm;

[0056] (2) Finite element meshing and material analysis are carried out on the initial design domain, the load condition and boundary condition of the pressure sensor during work are obtained, the design variable is the relative density of each element in the design domain, the constraint condition is that the volume constraint of the material usage ratio is less than or equal to 0.3 and the stress constraint that the global maximum stress is not more than 80Mpa, and the optimization target is to maximize the structural stiffness;

[0057] (3) Topology optimization is carried out on the optimization target and design area in step (2) under 0.1Mpa pressure working condition, and the initial topology optimization configuration of the thin film 6 front surface structure layer is obtained, which includes long beam 3, ring center short cross beam reinforcing rib 4, center short cross beam 5 with complete force transmission path and irregular island structure without complete force transmission path;

[0058] (4) removing unnecessary structural small features in the initial topological optimization configuration, which are irregular island structures without complete force transmission paths, and reconstructing according to process requirements and in accordance with the initial topological optimization results to obtain a thin film structure layer.

[0059] Referring to Figure 1 , an anti-overload pressure sensor chip based on topological optimization design, the sensor chip is divided into a structure layer and a thin film layer in structure.

[0060] Referring to Figure 1 , the structure layer comprises a square groove 13, a long beam 3, a ring center short cross beam reinforcing rib 4, a center short cross beam 5, the square groove 13 is a square outer frame of the front structure layer of the thin film 6, connected with the roots of the four long beams 3, the long beam 3 comprises a first long beam 3-1, a second long beam 3-2, a third long beam 3-3 and a fourth long beam 3-4, the ring center short cross beam reinforcing rib 4 comprises a first reinforcing rib 4-1, a second reinforcing rib 4-2, a third reinforcing rib 4-3 and a fourth reinforcing rib 4-4, the center short cross beam 5 is arranged along the center of the front of the thin film 6, the first reinforcing rib 4-1, the second reinforcing rib 4-2, the third reinforcing rib 4-3 and the fourth reinforcing rib 4-4 are respectively connected with the center short cross beam 5 along the right upper, right lower, left lower and left upper directions of the center of the front of the thin film 6, the first reinforcing rib 4-1 is respectively connected with the first long beam 3-1 and the second long beam 3-2, the second reinforcing rib 4-2 is respectively connected with the second long beam 3-2 and the third long beam 3-3, the third reinforcing rib 4-3 is respectively connected with the third long beam 3-3 and the fourth long beam 3-4, and the fourth reinforcing rib 4-4 is respectively connected with the fourth long beam 3-4 and the first long beam 3-1.

[0061] The roots of the long beams 3 are respectively provided with pressure sensitive resistance strips 7, the stress concentration area of the root of the first long beam 3-1 is provided with a first pressure sensitive resistance strip 7-1, the stress concentration area of the root of the second long beam 3-2 is provided with a second pressure sensitive resistance strip 7-2, the stress concentration area of the root of the third long beam 3-3 is provided with a third pressure sensitive resistance strip 7-3, and the stress concentration area of the root of the fourth long beam 3-4 is provided with a fourth pressure sensitive resistance strip 7-4. The effective length of all the pressure sensitive resistance strips 7 is along the crystal direction with the largest piezoresistive coefficient, the metal lead 8 connects the first pressure sensitive resistance strip 7-1 to the fourth pressure sensitive resistance strip 7-4 to form a Wheatstone bridge, and connects the Wheatstone bridge with four pads 9 arranged on the substrate to realize the input and output of the voltage signal, wherein the substrate is an n-type single crystal silicon element 1.

[0062] Referring to Figure 1The first metal lead 8-1 connects the left end of the first piezoresistor strip 7-1 with the first pad 9-1, and the second metal lead 8-2 connects the right end of the first piezoresistor strip 7-1 with the second pad 9-2; the third metal lead 8-3 connects the upper end of the second piezoresistor strip 7-2 with the second pad 9-2, and the fourth metal lead 8-4 connects the lower end of the second piezoresistor strip 7-2 with the third pad 9-3; the fifth metal lead 8-5 connects the right end of the third piezoresistor strip 7-3 with the third pad 9-3, and the sixth metal lead 8-6 connects the left end of the third piezoresistor strip 7-3 with the fourth pad 9-4; the seventh metal lead 8-7 connects the lower end of the fourth piezoresistor strip 7-4 with the fourth pad 9-4, and the eighth metal lead 8-8 connects the upper end of the fourth piezoresistor strip 7-4 with the first pad 9-1.

[0063] Referring to Figure 3 The back of the n-type monocrystalline silicon element 1 is combined with the glass substrate 2 by vacuum bonding. The back of the n-type monocrystalline silicon element is provided with a cavity, and the two are tightly combined to form a sealed cavity, and the differential pressure is measured through the through hole 12.

[0064] The working principle of the present application is as follows:

[0065] When the sensor chip is subjected to pressure, the thin film 6 begins to deform under the action of the differential pressure, the long beam 3 in the front structure layer of the thin film 6 causes stress concentration in the piezoresistor area, thereby ensuring the sensitivity, and the ring center short cross beam reinforcing rib 4 and the center short cross beam 5 jointly act to increase the rigidity of the pressure sensor and improve the overload capacity. At the same time, the cavity provided on the back of the n-type monocrystalline silicon element 1 has a side length slightly larger than that of the structure layer, and the two are misaligned to shift the stress extreme point at the bottom of the back cavity, so that the maximum stress point is shifted to the root of the long beam 3 of the structure layer, thereby improving the overload capacity of the pressure sensor.

[0066] The preparation method of the sensor chip of the present application is as follows:

[0067] Referring to Figure 4 The present application provides a preparation method of an anti-overload pressure sensor chip based on topological optimization design, comprising the following steps:

[0068] Step 1: performing photoetching and ion implantation for light boron ion doping on the front surface of the n-type monocrystalline silicon element 1 to form a first piezoresistor strip 7-1, a second piezoresistor strip 7-2, a third piezoresistor strip 7-3 and a fourth piezoresistor strip 7-4, respectively, and then performing annealing;

[0069] Step 2: performing photoetching and ion implantation for heavy boron ion doping on the front surface of the product obtained in step 1 to form an ohmic contact area 10, and then performing annealing;

[0070] Step 3, etching the contact hole 11 on the product obtained in step 2 by using dry etching technology;

[0071] Step 4, performing photolithography on the product obtained in step 3 by using the metal lead 8 mask, then performing magnetron sputtering and stripping to form the metal lead 8 and the pad 9, and then performing high-temperature alloying treatment, wherein the metal lead 8 is parallel to the four edges of the square groove 13, and the four pads are located at the four corners of the square groove 13;

[0072] Step 5, performing photolithography on the product obtained in step 4, and etching the front surface of the n-type monocrystalline silicon element 1 by using dry etching technology to obtain the square groove 13, the long beam 3, the ring center short cross beam reinforcing rib 4 and the center short cross beam 5;

[0073] Step 6, performing photolithography on the back surface of the n-type monocrystalline silicon element 1 obtained in step 4 by using a back cavity etching mask, and etching to form a cavity by using dry etching technology;

[0074] Step 7, performing laser drilling on the glass substrate 2 to form the through hole 12;

[0075] Step 8, anodically bonding the n-type monocrystalline silicon element 1 prepared in step 7 with the glass substrate 2 treated in step 6 to obtain an anti-overload pressure sensor chip based on topological optimization design.

[0076] Table 1 below is a simulation performance comparison between the pressure resistance pressure sensor structure of the present application and a flat membrane structure sensor of the same range and sensitivity, wherein the pressure is 100 kPa, the resistance is arranged at the center of the four edges of the square membrane of each sensor structure, the Von Mises is the average stress value at the resistance arrangement, and the Von Mises (Max) is the global maximum stress value of the pressure sensor chip. It can be seen that the pressure sensor of the present application has higher overload capacity under the condition of ensuring a certain sensitivity.

[0077]

[0078] The above only describes one embodiment of the present application, which is not all or the only embodiment. Any equivalent transformation of the technical scheme of the present application adopted by a person of ordinary skill in the art by reading the present application is covered by the claims of the present application.

Claims

1. A design method of an anti-overload pressure sensor chip based on topological optimization design, characterized in that, The design method comprises the following steps: (1) According to the design requirements of the pressure sensor chip, the initial design structure parameters and the design area are selected, the initial design refers to selecting the n-type monocrystalline silicon element (1) front surface without long beam (3), ring center short cross beam reinforcing rib (4) and center short cross beam (5), and the design area is a square groove (13) area with the same length as the square outer frame of the thin film front structure layer, and the length is 4-5 mm; (2) The finite element grid division and material analysis are carried out on the initial design domain, the load condition and the boundary condition of the pressure sensor during work are obtained, the design variable is the relative density of each element in the design domain, the constraint condition is that the volume constraint of the material usage body ratio is less than or equal to 0.3 and the stress constraint that the global maximum stress is not more than 80 MPa, and the optimization target is to maximize the structural stiffness; (3) The optimization target and the design area in step (2) are subjected to topology optimization under the condition of 0.1 MPa pressure, and the initial topology optimization configuration of the thin film front structure layer is obtained, the initial topology optimization configuration of the thin film front structure layer comprises long beam (3), ring center short cross beam reinforcing rib (4), center short cross beam (5) and irregular island structure without complete force transmission path; (4) The irregular island structure without complete force transmission path in the initial topology optimization configuration is removed, the thin film front structure layer is obtained according to the process requirements and according to the initial topology optimization result.

2. An anti-overload pressure sensor chip based on topology optimization design, characterized in that, The anti-overload pressure sensor chip obtained by the design method of claim 1 comprises an n-type monocrystalline silicon element (1) and a glass substrate (2) bonded with the n-type monocrystalline silicon element (1) by anode, a cavity is formed in the back of the n-type monocrystalline silicon element (1), and the n-type monocrystalline silicon element (1) and the glass substrate (2) are tightly bonded to form a sealed cavity; the top wall surface of the sealed cavity is provided with a diaphragm pressure sensing structure, the diaphragm pressure sensing structure comprises a thin film front structure layer and a thin film layer, the thin film front structure layer is formed by dry etching the front surface of the n-type monocrystalline silicon element (1), and the thin film layer is formed by dry etching the cavity on the back of the n-type monocrystalline silicon element (1); The thin film front structure layer is composed of square grooves (13), long beams (3), ring center short cross beam reinforcing ribs (4) and center short cross beams (5); the square groove (13) is a square outer frame of the thin film front structure layer, and is connected with roots of the four long beams (3); the long beam (3) is composed of a first long beam (3-1), a second long beam (3-2), a third long beam (3-3) and a fourth long beam (3-4), the four long beams are arranged in a cross shape, and first, second, third and fourth pressure sensitive resistor strips (7-1), (7-2), (7-3) and (7-4) are arranged at roots of the four long beams respectively, and the pressure sensitive resistor strips (7) are used for converting external pressure signals into voltage signals; the ring center short cross beam reinforcing rib (4) is composed of first, second, third and fourth reinforcing ribs (4-1), (4-2), (4-3) and (4-4), and is arranged between adjacent long beams (3), and the center short cross beam (5) is arranged in the middle of a square space surrounded by the four reinforcing ribs; the center short cross beam (5) is provided with a chamfer in the middle; the first, second, third and fourth pressure sensitive resistor strips (7-1), (7-2), (7-3) and (7-4) are connected to form a Wheatstone bridge through metal leads (8) and pads (9); The thin film layer is composed of a thin film (6), and is used for supporting the thin film front structure layer.

3. The design method of the overload-resistant pressure sensor chip based on the topological optimization design according to claim 2, characterized in that: The square cavity opened on the back of the thin film (6) has a depth of 100% to 200% of the film thickness; The square back cavity opened on the back of the thin film (6) has a side length of 100 to 300 μm more than the square groove opened on the front, and is 4.1 mm to 5.3 mm.

4. The overload-resistant pressure sensor chip based on the topological optimization design according to claim 2, characterized in that: The Wheatstone bridge is specifically: the first pressure sensitive resistor strip (7-1) is connected with the first pad (9-1) and the second pad (9-2) through the first metal lead (8-1) and the second metal lead (8-2) respectively; the second pressure sensitive resistor strip (7-2) is connected with the second pad (9-2) and the third pad (9-3) through the third metal lead (8-3) and the fourth metal lead (8-4) respectively; the third pressure sensitive resistor strip (7-3) is connected with the third pad (9-3) and the fourth pad (9-4) through the fifth metal lead (8-5) and the sixth metal lead (8-6) respectively; and the fourth pressure sensitive resistor strip (7-4) is connected with the first pad (9-1) and the fourth pad (9-4) through the seventh metal lead (8-7) and the eighth metal lead (8-8) respectively; and the four pads are located at four corners of the square groove (13).

5. The overload-resistant pressure sensor chip based on the topological optimization design according to claim 2, characterized in that: The square groove (13) of the thin film front structure layer has a side length of 4mm-5mm; The long beam (3), the ring center short cross beam reinforcing rib (4) and the center short cross beam (5) of the thin film front structure layer have the same thickness, which is 100%-200% of the thickness of the thin film layer; The long beam (3), the ring center short cross beam reinforcing rib (4) and the center short cross beam (5) of the thin film front structure layer have the same width, which is 200μm; The long beam (3) of the thin film front structure layer is provided with a round corner at the root, and the pressure sensitive resistor strip (7) is arranged on the symmetry axis of the long beam (3); The glass substrate (2) is provided with a through hole (12) in the middle, and the hole diameter is 0.5mm-1mm; the through hole (12) is used for passing in external gas pressure to realize differential pressure measurement.

6. A method of manufacturing an anti-overload pressure sensor chip based on topological optimization design according to any one of claims 2-5, characterized in that, The method comprises the following steps: Step 1, light etching, ion implantation and light doping of boron ions are performed on the front surface of the n-type single crystal silicon element (1) to form a first pressure sensitive resistor strip (7-1), a second pressure sensitive resistor strip (7-2), a third pressure sensitive resistor strip (7-3) and a fourth pressure sensitive resistor strip (7-4); Step 2, the front surface of the product obtained in step 1 is subjected to light etching, ion implantation and heavy doping of boron ions again to form an ohmic contact area (10); Step 3, a contact hole (11) is etched on the front surface of the product obtained in step 2 by using dry etching technology; Step 4, light etching is performed on the front surface of the product obtained in step 3 by using a metal lead (8) mask, then magnetic sputtering and stripping are performed to form a metal lead (8) and a pad (9), and high-temperature alloying treatment is performed; the metal lead (8) is parallel to the four edges of the square groove (13), and the four pads are located at the four corners of the square groove (13); Step 5, light etching is performed on the front surface of the product obtained in step 4, and dry etching technology is used to etch the front surface of the n-type single crystal silicon element (1) to obtain a square groove (13), a long beam (3), a ring center short cross beam reinforcing rib (4) and a center short cross beam (5); Step 6, the back surface of the n-type single crystal silicon element (1) obtained in step 4 is subjected to light etching by using a back cavity etching mask, and a cavity is formed by using dry etching technology; Step 7, a through hole (12) is formed in the glass substrate (2) by laser drilling; Step 8, the n-type single crystal silicon element (1) prepared in step 7 is anodically bonded to the glass substrate (2) treated in step 6 to obtain an anti-overload pressure sensor chip based on topological optimization design.

7. The method of claim 6, wherein the method further comprises: forming a plurality of holes in the top surface of the sensor chip; and forming a plurality of holes in the bottom surface of the sensor chip. After the four pressure sensitive resistor strips are formed in step 1, annealing treatment is performed to further uniform the impurity doping concentration of the pressure sensitive resistor strips.

8. The method of claim 6, wherein the anti-overload pressure sensor chip is prepared by the following steps: After the ohmic contact area (10) is formed in step 2, annealing treatment is performed to further uniform the impurity doping concentration of the ohmic contact area (14). ​

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