Pressure sensor and manufacturing method thereof

Abstract

The invention provides a pressure sensor and a manufacturing method thereof, and relates to the technical field of sensing. The pressure sensor provided by the invention comprises a substrate which is provided with a first surface, the first surface is provided with a plurality of blind holes, the plurality of blind holes are arranged in an array, and the first surface is the upper surface or the lower surface of the substrate; the piezoresistive element is arranged on the first surface, and the piezoresistive element is used for converting a pressure signal stressed by the piezoresistive element into an electric signal; the electrode is connected to the piezoresistive element, and the electrode is used for being connected with an external circuit so as to transmit the electric signal. The pressure sensor provided by the invention can have high sensitivity and high linearity in a pressure measuring range.

Description

Technical Field

[0001] The present application relates to the field of sensing technology, and in particular to a pressure sensor and a manufacturing method thereof. Background Art

[0002] Micro-Electro-Mechanical Systems (MEMS) pressure sensors are mainly divided into capacitive and resistive types. Capacitive sensors have been gradually replaced by silicon piezoresistive sensors due to their complex process and high cost. Among them, piezoresistive sensors have the characteristics of small size, high reliability, low cost and suitability for mass production.

[0003] The resistor chip of the MEMS pressure sensor is based on the piezoresistive effect of the semiconductor material silicon. The semiconductor silicon is diffused onto the substrate to form a Wheatstone bridge. When the varistor is subjected to mechanical stress, the pressure is converted into a voltage output through the Wheatstone bridge.

[0004] In the low pressure range (below 10kPa), MEMS piezoresistive pressure sensors need to have high sensitivity and good linearity to meet the pressure measurement requirements. Sensitivity refers to the sensor's response to pressure changes, while linearity involves the linear relationship between the sensor output and the actual pressure. The key factors affecting the sensitivity and nonlinearity of pressure sensors include the pressure sensitive membrane structure design, structure size and force deformation. Therefore, it is urgent to improve the sensitivity and linearity of pressure sensors through the structural design of the pressure sensitive membrane. Summary of the invention

[0005] The present application provides a pressure sensor and a manufacturing method thereof. The pressure sensor includes a substrate having a plurality of blind hole structures arranged in an array, and can have high sensitivity and high linearity within a pressure range.

[0006] In order to achieve the above objectives, this application provides the following technical solutions:

[0007] A first aspect of the present application provides a pressure sensor, comprising: a substrate having a first surface, the first surface being provided with a plurality of blind holes, the plurality of blind holes being arranged in an array, the first surface being an upper surface or a lower surface of the substrate;

[0008] A piezoresistive element, disposed on the first surface, and configured to convert a pressure signal of the piezoresistive element into an electrical signal;

[0009] An electrode is connected to the piezoresistive element, and the electrode is used to connect to an external circuit to transmit the electrical signal.

[0010] In a possible implementation manner, the percentage of the contour area of ​​the blind hole, which is an orthographic projection of the plane where the first surface of the substrate is located, to the surface area of ​​the first surface is 5%-80%.

[0011] In a possible implementation manner, the outline shape of the blind hole as projected on the plane where the first surface is located is circular, rectangular or elliptical.

[0012] In a possible implementation manner, the blind hole has a depth of 1-10 μm.

[0013] In a possible implementation, the plurality of blind holes are distributed on the first surface of the substrate in multiple rows and columns, and the number of columns of the plurality of blind holes is greater than or equal to the number of rows; or the number of columns of the plurality of blind holes is less than the number of rows.

[0014] In a possible implementation manner, along a row direction of the plurality of blind holes, distances between adjacent blind holes are equal; and / or along a column direction of the plurality of blind holes, distances between adjacent blind holes are equal.

[0015] In a possible implementation manner, the plurality of blind holes are arranged in two rows and four columns, or the plurality of blind holes are arranged in three rows and three columns.

[0016] In a possible implementation, the substrate is a silicon substrate or an SOI substrate, wherein the SOI substrate includes a bottom silicon layer, a silicon dioxide buried oxide layer, and a top silicon layer which are stacked in sequence.

[0017] The pressure sensor provided in the first aspect of the present application includes at least the following beneficial effects:

[0018] Under the condition that the thickness and area of ​​the substrate film remain unchanged, a blind hole is set on the substrate to change the stress distribution around the piezoresistive element. Under the same external load, the stress on the piezoresistive element can be increased, thereby improving the sensitivity. At the same time, the existence of the blind hole does not completely and significantly reduce the film stiffness, but still controls it within the range of small deformation to ensure the nonlinearity of the sensor. This solves the problem that the two solutions to increase the sensitivity, namely reducing the film thickness or increasing the film area, will increase the deformation within a fixed range, thereby increasing the nonlinearity.

[0019] A second aspect of the present application provides a method for manufacturing a pressure sensor, which is used to manufacture the pressure sensor provided by any of the above technical solutions, and the manufacturing method comprises the following steps:

[0020] providing a substrate;

[0021] Photolithography and light doping are performed on the first surface of the substrate to form a light diffusion resistance region;

[0022] Disposing an oxide layer on the first surface, wherein the oxide layer covers the light diffusion resistance region;

[0023] Photolithography, window opening and etching are performed on the oxide layer to form a window to expose a portion of the light diffusion resistor region;

[0024] Photolithography and heavy doping are performed on the lightly diffused resistance region to form a heavily extended resistance region, wherein the heavily extended resistance region and the lightly diffused resistance region constitute the piezoresistive element;

[0025] Depositing a metal layer on the oxide layer, and etching the metal layer to form an electrode region, wherein the electrode region is electrically connected to the re-expanded resistance region;

[0026] Opening windows and etching on the oxide layer to form through holes, so as to form exposed areas on the substrate;

[0027] The plurality of blind holes are formed on the exposed area by photolithography and etching.

[0028] In a possible implementation, the substrate has at least two opening areas, both of which are provided with the multiple blind holes, and in the two opening areas, the percentage of the contour area of ​​the blind holes projected on the plane where the first surface of the substrate is located to the surface area of ​​the first surface is different.

[0029] The manufacturing method of the pressure sensor provided in the second aspect of the present application has all the beneficial effects of the pressure sensor provided in the first aspect of the present application, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A schematic diagram of the overall structure of the pressure sensor provided in the embodiment of the present application;

[0032] Figure 2 A top view of a substrate provided with a blind hole (the bottom projection is a rectangle) of a pressure sensor provided in an embodiment of the present application;

[0033] Figure 3 A top view of a substrate provided with a blind hole (the bottom surface projection is circular) of a pressure sensor provided in an embodiment of the present application;

[0034] Figure 4 A cross-sectional view of a substrate of a pressure sensor provided in an embodiment of the present application (blind holes are provided on the top surface);

[0035] Figure 5 A cross-sectional view of a substrate of a pressure sensor provided in an embodiment of the present application (blind holes are provided on the bottom surface);

[0036] Figure 6 A manufacturing process flow chart of a pressure sensor provided in an embodiment of the present application using silicon as a substrate;

[0037] Figure 7 A manufacturing process flow chart of a pressure sensor provided in an embodiment of the present application using SOI as a substrate;

[0038] Figure 8 for Figure 6 Input pressure-output voltage test curve of the pressure sensor obtained by the manufacturing process.

[0039] Description of reference numerals:

[0040] 100, substrate; 110, blind hole; 120, etched cavity; 130, pad; 200, passivation layer; 300, piezoresistive element; 400, electrode; 500, glass; 510, opening.

[0041] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] As described in the background technology, Micro-Electro-Mechanical Systems (MEMS) pressure sensors are mainly divided into capacitive and resistive types. Capacitive sensors have been gradually replaced by silicon piezoresistive sensors due to their complex process and high cost. Among them, piezoresistive sensors have the characteristics of small size, high reliability, low cost and suitability for mass production. The resistor chip of the MEMS pressure sensor is based on the piezoresistive effect of semiconductor material silicon. Semiconductor silicon is diffused onto the substrate to form a Wheatstone bridge. When the varistor is subjected to mechanical stress, the pressure is converted into a voltage output through the Wheatstone bridge.

[0043] In the low pressure range (below 10kPa), MEMS piezoresistive pressure sensors need to have high sensitivity and good linearity to meet the pressure measurement requirements. Sensitivity refers to the sensor's response to pressure changes, while linearity involves the linear relationship between the sensor output and the actual pressure. The key factors affecting the sensitivity and nonlinearity of pressure sensors include the pressure sensitive membrane structure design, structure size and force deformation. Therefore, it is urgent to improve the sensitivity and linearity of pressure sensors through the structural design of the pressure sensitive membrane.

[0044] In response to the above technical problems, the embodiments of the present application provide a pressure sensor and a method for manufacturing the same. When the thickness and area of ​​the substrate film remain unchanged, a blind hole is set on the substrate to change the stress distribution around the piezoresistive element. Under the same external load, the stress on the piezoresistive element can be increased, thereby improving the sensitivity. At the same time, the existence of the blind hole does not completely and significantly reduce the film stiffness, but still controls it within the range of small deformation, thereby ensuring the nonlinearity of the sensor. This solves the problem that the two solutions to improve the sensitivity, namely, reducing the film thickness or increasing the film area, both increase the deformation within a fixed range, thereby increasing the nonlinearity.

[0045] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of this application.

[0046] Combination Figures 1 to 8 The pressure sensor provided in the embodiment of the present application includes: a substrate 100, having a first surface, the first surface is provided with a plurality of blind holes 110, the plurality of blind holes 110 are arranged in an array, and the first surface can be the upper surface or the lower surface of the substrate 100; a piezoresistive element 300, which is arranged on the first surface, and the piezoresistive element 300 is used to convert the pressure signal of the piezoresistive element itself into an electrical signal; an electrode 400, which is connected to the piezoresistive element 300, and the electrode 400 is used to connect to an external circuit to transmit an electrical signal.

[0047] In this way, when the thickness and area of ​​the substrate film remain unchanged, a blind hole is set on the substrate to change the stress distribution around the piezoresistive element. Under the same external load, the stress on the piezoresistive element can be increased, thereby improving the sensitivity. At the same time, the existence of the blind hole does not completely and significantly reduce the film stiffness, but still controls it within the range of small deformation to ensure the nonlinearity of the sensor. This solves the problem that the two solutions to increase the sensitivity, namely reducing the film thickness or increasing the film area, will increase the deformation within a fixed range, thereby increasing the nonlinearity.

[0048] In more examples, the pressure sensor may further include an oxide layer 200, which acts as a passivation layer and is disposed on the first surface to provide protection for the surface of the sensor device. A through hole is provided on the oxide layer 200, and the through hole is correspondingly connected to the blind hole 110. The piezoresistive element 300 is located between the substrate 100 and the oxide layer 200.

[0049] In some embodiments, the percentage of the contour area of ​​the blind hole 110 projected on the plane where the first surface of the substrate 100 is located is 5%-80% of the surface area of ​​the first surface. For example, the percentage of the contour area of ​​the blind hole 110 projected on the plane where the first surface of the substrate 100 is located is 5%, or the percentage of the contour area of ​​the blind hole 110 projected on the plane where the first surface of the substrate 100 is located is 80%, or the percentage of the contour area of ​​the blind hole 110 projected on the plane where the first surface of the substrate 100 is 42%.

[0050] In this case, the setting range of the blind holes 110 on the substrate 100 is controlled within a reasonable proportion, which is beneficial for the sensor to maintain both high sensitivity and linearity. It is not difficult to understand that when the setting ratio of the blind holes 110 is lower than 5%, the rigidity of the substrate 100 is higher, but the sensitivity improvement effect is smaller, and when the setting ratio of the blind holes 110 is higher than 80%, the area of ​​the holes accounts for too large a proportion, and the rigidity of the pressure sensing membrane structure formed after the substrate 100 is opened is significantly reduced, making it easier to deform under pressure, which is easy to cause insufficient structural strength, affecting the durability and reliability of the sensor.

[0051] In some embodiments, the outline shape of the blind hole 110 projected on the plane where the first surface is located is circular, rectangular or elliptical. Exemplarily, the outline shape of the blind hole 110 projected on the plane where the first surface is located is circular, and the stress distribution around the circular hole is relatively uniform, which can reduce stress concentration and thus reduce the probability of cracking of the substrate 100. Moreover, circular holes are relatively easy to manufacture in micromachining, and circular structures are not prone to sharp corner defects during lithography and etching. In another example, the outline shape of the blind hole 110 projected on the plane where the first surface is located is elliptical, and the stress distribution of the elliptical hole on the substrate 100 is between circular and rectangular. The stress distribution and sensitivity direction can be adjusted by setting the ratio of the major axis and the minor axis, that is, the elliptical hole can enhance the sensitivity in a specific direction by adjusting the direction of the major axis, which is beneficial to the force directionality detection of the sensor.

[0052] Furthermore, when the outline shape of the blind hole 110 in the orthographic projection on the plane where the first surface is located is a rectangle, it is set to be a rounded rectangle to prevent stress concentration after the substrate 100 is opened.

[0053] In some embodiments, the blind hole 110 has a hole depth of 1-10 μm. For example, the blind hole 110 has a hole depth of 1 μm, or the blind hole 110 has a hole depth of 10 μm, or the blind hole 110 has a hole depth of 5 μm. If the blind hole 110 has a depth of less than 1 μm, the effect on improving the deformation ability of the sensor is too small. If the blind hole 110 has a depth of more than 10 μm, it is close to the thickness of the substrate 100 itself, which is inconvenient to process.

[0054] In some embodiments, the plurality of blind holes 110 are distributed in multiple rows and columns on the first surface of the substrate 100, and the number of columns of the plurality of blind holes 110 is greater than or equal to the number of rows. For example, two rows and three columns of the blind holes 110 are distributed on the first surface of the substrate 100; or, the number of columns of the plurality of blind holes 110 is less than the number of rows, for example, four rows and two columns of the blind holes 110 are distributed on the first surface of the substrate 100.

[0055] In some embodiments, the distances between adjacent blind holes 110 are equal along the row direction of the blind holes 110; or, the distances between adjacent blind holes 110 are equal along the column direction of the blind holes 110, or, the distances between adjacent blind holes 110 are equal along the row direction and the column direction of the blind holes 110. In this way, by precisely controlling the distances between the blind holes 110, it is possible to ensure a more uniform stress distribution in the entire sensing area. This uniform stress distribution helps reduce nonlinear errors, thereby improving the linearity of the sensor.

[0056] In some embodiments, the plurality of blind holes 110 are arranged in two rows and four columns, or the plurality of blind holes 110 are arranged in three rows and three columns.

[0057] In some embodiments, the substrate 100 is a silicon substrate 100 or an SOI substrate 100, wherein the SOI substrate 100 includes a bottom silicon layer, a silicon dioxide buried oxide layer, and a top silicon layer stacked in sequence. It can be understood that the bottom silicon layer is a silicon layer that provides mechanical support, and the top silicon layer is an active layer used for device manufacturing, which is usually thinner, with a thickness of tens to hundreds of nanometers.

[0058] It is not difficult to understand that the traditional C-shaped diaphragm, that is, the substrate 100 is thinned, if high sensitivity needs to be met, it is mainly achieved by increasing the deformation of the pressure membrane, but at the same time, the increase in the membrane deformation is likely to cause the pressure sensor to produce a large deformation nonlinear output. On the basis of the existing structure, the embodiment of the present application sets a blind hole 110 structure on the substrate 100 to provide a new pressure membrane structure, which can take into account the high sensitivity and nonlinearity of the pressure sensor within the measuring range.

[0059] In a second aspect, an embodiment of the present application provides a method for manufacturing a pressure sensor, which is used to manufacture the pressure sensor provided by any embodiment of the first aspect, and the manufacturing method comprises the following steps:

[0060] A substrate is provided, which may be a silicon substrate or an SOI substrate.

[0061] Photolithography and light doping are performed on the first surface of the substrate to form a light diffusion resistance area, wherein the photolithography step includes photoresist coating, exposure and development, and the light doping includes ion implantation, diffusion and photoresist removal. It can be understood that the ion implantation process is to perform ion implantation in the area defined by the photolithography, which is achieved by accelerating charged ions (such as boron or phosphorus) into the substrate surface.

[0062] It can be understood that light doping means that the concentration of implanted ions is low to form lightly doped areas, and the diffusion process is a heat treatment at high temperature to diffuse the implanted ions in the substrate to form uniformly doped areas. The resistance characteristics of these areas are controlled by the doping concentration and diffusion depth.

[0063] After the diffusion is completed, the remaining photoresist is removed using a chemical solvent, leaving behind the doped pattern.

[0064] An oxide layer is provided on the first surface, and the oxide layer covers the lightly doped diffusion resistor region, that is, after the lightly doped diffusion resistor region is formed, an oxide layer is deposited thereon, for example, the oxide layer is silicon dioxide (SiO2), and can be formed by methods such as thermal oxidation or chemical vapor deposition (CVD). Thus, the oxide layer can act as an electrical insulator to prevent current from flowing in undesired areas, and the oxide layer can protect the lightly doped diffusion resistor region below from being affected by chemicals or physical damage in subsequent processing steps. At the same time, in subsequent photolithography and etching processes, the oxide layer can act as a mask material to help define the shape and position of the microstructure.

[0065] Photolithography and window etching are performed on the oxide layer to form a window to expose part of the light diffusion resistance area. Photolithography and heavy doping are performed on the light diffusion resistance area to form a heavy expansion resistance area. The heavy expansion resistance area and the light diffusion resistance area constitute a piezoresistive element. Specifically, after the photolithography step, wet or dry etching technology is used to remove the exposed oxide layer to form a window. Heavy doping is to introduce more dopants (such as boron or phosphorus) into the light diffusion resistance area through ion implantation or diffusion process to increase the doping concentration. These heavily doped areas are the heavy expansion resistance areas. In this way, these heavy expansion resistance areas and the light diffusion resistance areas together constitute a piezoresistive element. The resistance of the piezoresistive element will change with the change of external pressure, thereby realizing pressure sensing.

[0066] A metal layer is deposited on the oxide layer, and the metal layer is etched to form an electrode region, and the electrode region is electrically connected to the re-expanded resistance region, wherein a layer of metal is deposited on the oxide layer, usually using physical vapor deposition (PVD) or chemical vapor deposition (CVD) technology. Exemplarily, the deposited metal is aluminum, and the material has good electrical conductivity, so that the formed electrode region is used to be electrically connected to the re-expanded resistance region. The electrode provides an electrical connection path between the external circuit and the piezoresistive element, so that the resistance change can be measured and converted into an electrical signal.

[0067] A through hole is formed by opening a window on the oxide layer and etching to form an exposed area on the substrate; and a plurality of blind holes are formed by photolithography and etching on the exposed area.

[0068] In some embodiments, the substrate has at least two opening areas, and both opening areas are provided with multiple blind holes. In the two opening areas, the percentage of the contour area of ​​the blind holes projected on the plane where the first surface of the substrate is located to the surface area of ​​the first surface is different. Exemplarily, there are four sector-shaped areas on the circular substrate. Along the clockwise direction, the percentage of the contour area of ​​the blind holes in the opening areas of the four sector-shaped areas projected on the plane where the first surface of the substrate is located to the surface area of ​​the first surface is 30%, 45%, 55% and 70% respectively. In this way, the embodiment of the present application can set different proportions of blind hole opening areas according to different stress state partitions of different wafers. Compared with the beam mold and beam island structure setting scheme, the design flexibility for improving the stress state of the sensor and the consistency of sensitivity is higher.

[0069] Furthermore, the substrate and the glass are bonded to form a silicon-glass bonding structure, and the glass is provided with openings. In this way, the bonded glass layer provides additional mechanical support for the silicon substrate, thereby enhancing the strength and rigidity of the entire structure. Moreover, the bonding of the glass with openings and silicon allows a cavity to be etched on one side of the glass to act as a reference pressure chamber that provides a stable reference pressure.

[0070] It should be noted that the pressure sensor provided in the first aspect of the embodiment of the present application and the pressure sensor obtained by the manufacturing method in the second aspect can be applied to gauge pressure or absolute pressure sensors.

[0071] refer to Figure 8 , which is a comparative test curve diagram of the pressure sensor made with silicon as substrate in the embodiment of the present application and the original sensor without blind holes. It is not difficult to see from the figure that under the same pressure signal, the pressure sensor in the embodiment of the present application has a higher voltage output, a higher pressure sensitivity, and maintains better linearity.

[0072] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0073] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0074] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0075] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0076] The various embodiments or implementation methods in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0077] It should be noted that the embodiments represented by "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing specific features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments that are explicitly or not explicitly described.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pressure sensor, characterized in that: include: A substrate having a first surface, wherein the first surface is provided with a plurality of blind holes, the plurality of blind holes are arranged in an array, and the first surface is an upper surface or a lower surface of the substrate; A piezoresistive element, disposed on the first surface, and configured to convert a pressure signal of the piezoresistive element into an electrical signal; An electrode is connected to the piezoresistive element, and the electrode is used to connect to an external circuit to transmit the electrical signal.

2. The pressure sensor according to claim 1, characterized in that: The percentage of the contour area of ​​the blind hole, which is orthographically projected on the plane where the first surface of the substrate is located, to the surface area of ​​the first surface is 5%-80%.

3. The pressure sensor according to claim 2, characterized in that: The outline shape of the blind hole in the orthographic projection on the plane where the first surface is located is circular, rectangular or elliptical.

4. The pressure sensor according to any one of claims 1 to 3, characterized in that: The blind hole has a hole depth of 1-10 μm.

5. The pressure sensor according to any one of claims 1 to 3, characterized in that: The plurality of blind holes are distributed on the first surface of the substrate in a plurality of rows and columns, and the number of columns of the plurality of blind holes is greater than or equal to the number of rows; or the number of columns of the plurality of blind holes is less than the number of rows.

6. The pressure sensor according to claim 5, characterized in that: Along the row direction of the plurality of blind holes, the distances between adjacent blind holes are equal; and / or, along the column direction of the plurality of blind holes, the distances between adjacent blind holes are equal.

7. The pressure sensor according to claim 5, characterized in that: The plurality of blind holes are arranged in two rows and four columns, or the plurality of blind holes are arranged in three rows and three columns.

8. The pressure sensor according to any one of claims 1 to 3, characterized in that: The substrate is a silicon substrate or an SOI substrate, wherein the SOI substrate comprises a bottom silicon layer, a silicon dioxide buried oxide layer and a top silicon layer which are stacked in sequence.

9. A method for manufacturing a pressure sensor, characterized in that: For manufacturing the pressure sensor according to any one of claims 1 to 8, the manufacturing method comprises the following steps: providing a substrate; Photolithography and light doping are performed on the first surface of the substrate to form a light diffusion resistance region; Disposing an oxide layer on the first surface, wherein the oxide layer covers the light diffusion resistance region; Photolithography, window opening and etching are performed on the oxide layer to form a window to expose a portion of the light diffusion resistor region; Photolithography and heavy doping are performed on the lightly diffused resistance region to form a heavily extended resistance region, wherein the heavily extended resistance region and the lightly diffused resistance region constitute the piezoresistive element; Depositing a metal layer on the oxide layer, and etching the metal layer to form an electrode region, wherein the electrode region is electrically connected to the re-expanded resistance region; Opening windows and etching on the oxide layer to form through holes, so as to form exposed areas on the substrate; The plurality of blind holes are formed on the exposed area by photolithography and etching.

10. The manufacturing method according to claim 9, characterized in that: The substrate has at least two opening areas, each of which is provided with the plurality of blind holes. In the two opening areas, the percentage of the contour area of ​​the blind holes projected on the plane where the first surface of the substrate is located to the surface area of ​​the first surface is different.

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