Method for reducing manufacturing cost of pressure sensor and pressure sensor

Abstract

The invention provides a method for reducing the manufacturing cost of a pressure sensor and the pressure sensor, and the method comprises the steps: providing a first substrate which comprises a bottom silicon layer, a buried oxide layer and a top silicon layer, forming a first doped region and a second doped region in a preset region of the top silicon layer from one side of the top surface of the top silicon layer; after the first doped region and the second doped region are formed, a cavity groove exposed by the bottom surface of the bottom silicon layer is formed in the bottom silicon layer from one side of the bottom surface of the bottom silicon layer, and the buried oxide layer is exposed out of the groove bottom of the cavity groove; according to the invention, ion implantation is carried out by taking the photoetching mask layer forming the cavity groove as a mask, so that the well region is formed in the preset region of the top silicon layer, a photomask is saved, and the preparation cost of the pressure sensor is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor device preparation, and in particular to a method for reducing the manufacturing cost of a pressure sensor and a pressure sensor. Background Art

[0002] The preparation of MEMS (micro-electro-mechanical system) pressure sensors usually involves multiple complex process steps, including photolithography, etching, thin film deposition, packaging, etc., which require the use of multiple masks.

[0003] However, in the current manufacturing process of MEMS pressure sensors, the complex preparation process and high production cost have seriously restricted their market promotion and application. Summary of the invention

[0004] The embodiment of the present invention provides a method for preparing a pressure sensor, which effectively utilizes the structure of the device itself, saves a photomask and thus reduces the preparation cost of the pressure sensor.

[0005] In order to solve the above technical problems, the technical solution of the present invention provides a method for reducing the manufacturing cost of a pressure sensor, comprising:

[0006] Providing a first substrate, comprising a bottom silicon layer, a buried oxide layer and a top silicon layer stacked in sequence;

[0007] From one side of the top surface of the top silicon layer, a first doping region and a second doping region are formed in a preset area of ​​the top silicon layer;

[0008] A patterned mask layer is formed on the bottom surface of the bottom silicon layer, wherein the mask layer includes a cavity groove window pattern and a blocking area, wherein the cavity groove window pattern corresponds to the preset area in a vertical direction, and a size of the cavity groove window pattern is larger than a size of the preset area;

[0009] Using the patterned mask layer as a mask, etching the bottom silicon in the cavity groove window pattern, with the etching endpoint staying on the surface of the buried oxide layer;

[0010] Using the patterned mask layer as a mask, ion implantation is performed from the bottom side of the bottom silicon layer to a preset well region position of the top silicon layer to form a well region, wherein the preset well region position corresponds to the cavity groove up and down;

[0011] A second substrate is provided, and the second substrate is bonded to the bottom surface of the bottom silicon layer of the first substrate to form a pressure sensor.

[0012] Optionally, the parameters of the N-type ion implantation include: the implantation material includes at least phosphorus, the implantation dose is 4e 15 ions / cm 2 ~6e15 ions / cm 2 The injection energy is between 110KeV and 130KeV, and the injection angle of the ions is between 6° and 8° away from the vertical direction.

[0013] Optionally, before forming the first doping region and the second doping region, the method further includes:

[0014] forming an oxide layer on a surface of the top silicon layer;

[0015] A first cutting mark is formed on the surface of the oxide layer, and the cutting road area is located outside the main body of the pressure sensor.

[0016] Optionally, before forming the cavity groove on the bottom surface of the bottom silicon layer, the method further includes:

[0017] Thinning the bottom surface of the bottom silicon layer and reducing the thickness of the first substrate to a first preset thickness;

[0018] The bottom surface of the thinned bottom silicon layer is subjected to chemical mechanical polishing.

[0019] Optionally, the first preset thickness is within 500 μm.

[0020] Optionally, the second substrate includes a first surface and a second surface that are opposite to each other, the first surface of the second substrate is bonded to the bottom surface of the bottom silicon layer, and further includes:

[0021] Thinning the second surface of the second substrate, and thinning the thickness of the bonded wafer to a second preset thickness;

[0022] The second surface of the thinned second substrate is subjected to chemical mechanical polishing.

[0023] Optionally, the second preset thickness is within 700 μm.

[0024] Optionally, forming a first doped region in a preset area in the top silicon layer specifically includes:

[0025] A P+ doped region on the surface of the oxide layer;

[0026] Evenly coating the photoresist on the surface of the oxide layer;

[0027] Expose, develop and bake the photoresist using a first photomask, wherein the first photomask includes a P+ doped region window pattern region and a blocking region;

[0028] A first ion implantation is performed to form a P+ doped region.

[0029] Optionally, forming a second doping region in a preset area in the top silicon layer specifically includes:

[0030] The photoresist is exposed, developed and baked by using a second photomask, wherein the second photomask includes a P-doped region window pattern region and a blocking region;

[0031] Performing a second ion implantation to form a P-doped region;

[0032] removing the photoresist;

[0033] Thermal annealing is performed on the surface of the second oxide to activate impurity atoms and repair lattice damage.

[0034] The technical solution of the present invention further provides a pressure sensor, including a pressure sensor prepared by the method for reducing the manufacturing cost of a pressure sensor, the pressure sensor comprising:

[0035] A first substrate, the first substrate comprising a bottom silicon layer, a buried oxide layer and a top silicon layer stacked in sequence;

[0036] a first doping region and a second doping region, wherein the first doping region and the second doping region are both located in the top silicon layer region;

[0037] a well region, wherein the well region surrounds the first doped region and the second doped region and completely fills the preset area;

[0038] A cavity groove is located in the bottom silicon layer, the cavity groove and the preset area are vertically opposite to each other and the buried oxide layer is exposed;

[0039] A second substrate is bonded to the bottom surface of the bottom silicon layer to form a cavity structure of the pressure sensor.

[0040] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0041] The method for reducing the manufacturing cost of the pressure sensor provided by the technical solution of the present invention performs N-type ion implantation on the top silicon layer by reusing the mask layer for forming the cavity groove. Therefore, in the process of preparing the N-type well region, a photomask is saved, thereby reducing the preparation cost of the pressure sensor. At the same time, the buried oxide layer in the cavity groove acts as a barrier layer. When ion implantation is performed, the injected ions will be hindered by the buried oxide layer, and the position scattering of the injected ions entering the lattice will increase, preventing the injection from being directly aligned with the lattice gap position, and the injection depth of the ions can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of a cross-sectional structure of a pressure sensor;

[0043] Figures 2 to 11It is a schematic cross-sectional structure diagram of each step of a method for reducing the manufacturing cost of a pressure sensor in one embodiment of the present invention. DETAILED DESCRIPTION

[0044] As described in the background art, in the current manufacturing process of MEMS pressure sensors, MEMS pressure sensors have problems of complex processes and high production costs.

[0045] Figure 1 A schematic diagram of the cross-sectional structure of a pressure sensor.

[0046] Please refer to Figure 1 , Figure 1 The preparation process of the pressure sensor shown generally includes the following:

[0047] Providing a SOl substrate 210;

[0048] An oxide layer 220 is formed on the surface of the top silicon layer 213 in the SOI substrate 210, and a cutting mark 230 penetrating the oxide layer 220 and the top silicon layer 213 is formed at an edge position of the oxide layer surface;

[0049] Performing N-type ion implantation on the surface of the oxide layer 220 through an N-type ion implantation mask to form a well region 240 in the top silicon layer 213;

[0050] After forming the N-type well region 240, P+ ion implantation and P- ion implantation are performed on the surface of the oxide layer 220 through a P+ ion implantation mask and a P- ion implantation mask, respectively, to form a P+ doping region 250 and a P- doping region 260 in the top silicon layer 213, respectively;

[0051] A cavity groove 2111 is formed on the bottom surface of the bottom silicon layer 211 in the SOI substrate 210 to expose the buried oxide layer 212 in the SOI substrate 210;

[0052] A second substrate 270 is provided, and the second substrate 270 is bonded to the bottom surface of the bottom silicon layer 211 to form a cavity structure of the MEMS pressure sensor.

[0053] The problem with the above-mentioned pressure sensor manufacturing process embodiment is that in the process of cavity etching, well area ion implantation, doping area doping and the like, exposure and development are required to form corresponding graphic areas respectively, thereby increasing the manufacturing cost of the pressure sensor.

[0054] In order to solve the above technical problems, an embodiment of the present invention provides a method for reducing the manufacturing cost of a pressure sensor, the method comprising:

[0055] Providing a first substrate, comprising a bottom silicon layer, a buried oxide layer and a top silicon layer stacked in sequence;

[0056] From one side of the top surface of the top silicon layer, a first doping region and a second doping region are formed in a preset area of ​​the top silicon layer;

[0057] A patterned mask layer is formed on the bottom surface of the bottom silicon layer, wherein the patterned mask layer includes a cavity groove window pattern and a blocking area, wherein the cavity groove window pattern corresponds to the preset area in a vertical direction, and a size of the cavity groove window pattern is larger than a size of the preset area;

[0058] Using the patterned mask layer as a mask, etching the bottom silicon in the cavity groove window pattern, with the etching endpoint staying on the surface of the buried oxide layer;

[0059] Using the patterned mask layer as a mask, ion implantation is performed from the bottom side of the bottom silicon layer to a preset well region position of the top silicon layer to form a well region, wherein the preset well region position corresponds to the cavity groove up and down;

[0060] A second substrate is provided, and the second substrate is bonded to the bottom surface of the bottom silicon layer of the first substrate to form a pressure sensor.

[0061] Since the cavity groove window pattern in the mask layer is vertically opposite to the preset area, the embodiment of the present application can still reuse the mask layer as a mask after the etching of the cavity groove is completed through the photolithography mask layer, and ion implantation is performed on the exposed buried oxide layer and the top silicon layer under the buried oxide layer to form a well region in the preset area of ​​the top silicon layer, thereby saving a photomask in the process of forming the well region, thereby reducing the preparation cost of the pressure sensor. At the same time, the buried oxide layer in the cavity groove acts as a barrier layer. When ion implantation is performed, the injected ions will be hindered by the buried oxide layer, and the position scattering of the injected ions entering the lattice will increase, preventing the injection from being directly aligned with the lattice gap position, thereby controlling the injection depth of the ions.

[0062] In order to make the above-mentioned purposes, features and beneficial effects of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the scope of protection of the present invention. The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0063] Figures 2 to 10 It is a schematic cross-sectional structure diagram of each step of a method for reducing the manufacturing cost of a pressure sensor in one embodiment of the present invention.

[0064] Please refer to Figure 2 , providing a first substrate.

[0065] The first substrate is specifically an SOI wafer, and the SOI wafer includes: a bottom silicon layer 100, a buried oxide layer 101 and a top silicon layer 102 stacked in sequence, and a surface a1 of the top silicon layer 102 and a bottom surface a2 of the bottom silicon layer 100 are opposite to each other.

[0066] Please refer to Figure 3 , an oxide layer 103 is formed on the surface a1 of the top silicon layer 102 .

[0067] A first cutting mark 104 is formed on the surface of the oxide layer 103 , and the first cutting mark 104 penetrates the oxide layer 103 and the top silicon layer 102 .

[0068] Specifically, the first cutting mark 104 is located at the cutting path of the first substrate, that is, outside the main body of the pressure sensor. Since the pressure sensor prepared on the wafer is packaged and cut through the cutting path, making the first cutting mark 104 will not cause damage to the pressure sensor, and thus will not affect the performance of the pressure sensor.

[0069] The method for forming the first cutting mark 104 includes: spin coating a photoresist layer on the first surface of the oxide layer 103; exposing and developing the photoresist layer using a mask with a cutting mark pattern to form a patterned first mask layer, wherein the first mask layer includes an Nth cutting mark window pattern and a blocking area, and the first cutting mark window pattern is located at the cutting path; using the first mask layer as a mask, etching the oxide layer 103 and the top silicon layer 102 in sequence until the first surface of the buried oxide layer 101 is exposed to form the first cutting mark 104; after forming the first cutting mark 104, removing the first mask layer.

[0070] It should be appreciated that the above is an example in which the material of the first mask layer is photoresist. In practical applications, the first mask layer may also be made of other materials and may also be formed in other ways, and the present invention is not limited thereto.

[0071] Please refer to Figure 4 A first doping region 105 and a second doping region 106 are respectively formed in a predetermined area i1 of the surface a1 of the top silicon layer 102 .

[0072] The method for forming the first doping region 105 comprises the following steps:

[0073] A photoresist layer is spin-coated on the first surface of the oxide layer 103 .

[0074] The photoresist layer is exposed and developed using a first photomask to pattern the photoresist layer and form a patterned second mask layer; the patterned second mask layer includes a first doping window pattern and a blocking area. The first doping window pattern is located in the preset area i1, and the preset area i1 is a device area of ​​the pressure sensor.

[0075] Using the patterned second mask layer as a mask, P+ ion implantation is performed on the oxide layer 103 and the top silicon layer 102 in the first doping window pattern to form the first doping region 105 in the top silicon layer 102. Figure 4 The second doping region is a high-concentration P-type doping region, and the implanted ions of the P+ ion implantation are trivalent impurity elements, specifically boron and gallium. The specific process of the second doping region is a common technical means in the art and will not be described in detail here.

[0076] The method for forming the second doping region 106 comprises the following steps:

[0077] After the first doping region 105 is prepared, the photoresist layer is exposed and developed using a second photomask to pattern the photoresist layer and form a patterned third mask layer; the patterned third mask layer includes a second doping window pattern and a blocking region. The second doping window pattern is also located in the preset region i1.

[0078] Using the patterned third mask layer as a mask, P- ion implantation is performed on the oxide layer 103 and the top silicon layer 102 in the second doping window pattern to form the second doping region 106 in the top silicon layer 102. Figure 4 The second doping region is a low-concentration P-type doping region, and the implanted ions of the P-ion implantation are trivalent impurity elements, specifically boron and gallium. The specific process of the second doping region is a common technical means in the art and will not be described in detail here.

[0079] The surface of the oxide layer 103 is ashed to remove the remaining third mask layer after pickling.

[0080] A thermal annealing process is performed on the surface of the oxide layer 103 to activate the impurity atoms and repair the lattice damage, wherein the temperature of the thermal annealing is between 900°C and 1000°C.

[0081] It should be noted that the surface of the oxide layer 103 may be thermally annealed after forming the first doping region 105 and the second doping region 106. Thermal annealing may also be performed separately during the process of forming the first doping region 105 and the second doping region 106. Of course, the specific process may be selected according to the needs and is not limited here.

[0082] Please refer to Figure 5 , the bottom silicon layer 100 is thinned from the bottom surface a2 of the bottom silicon layer 100 to reduce the thickness of the first substrate.

[0083] Thinning the bottom silicon layer 100 includes the following steps:

[0084] The bottom surface a2 of the bottom silicon layer 100 is dry-etched to reduce the thickness of the first substrate to a first preset thickness. The bottom surface a2 of the bottom silicon layer 100 after thinning is chemically mechanically polished.

[0085] Specifically, the gas used for the dry etching is carbon tetrafluoride, the etching temperature is room temperature, and the pressure of the carbon tetrafluoride is 170-190 mTorr. Of course, the specific dry etching conditions can be adjusted according to actual conditions, and they are not used as factors to limit the scope of protection of the present invention. Specifically, the first preset thickness is about 500 μm. Of course, those skilled in the art should be aware that there are many ways to thin the bottom silicon layer 100, and the present invention is not limited to this.

[0086] Please continue to refer to Figure 6 After thinning the bottom silicon layer 100, a patterned mask layer 111 is formed on the bottom surface of the bottom silicon layer, and the patterned mask layer 111 includes a cavity groove window pattern 112 and a blocking area. The cavity groove window pattern 112 corresponds to the preset area i1 up and down, and the size of the cavity groove window pattern 112 is larger than the size of the preset area i1.

[0087] The preparation method for forming the mask layer 111 is the same as the preparation method for the first mask layer to the third mask layer, which will not be described in detail herein.

[0088] Please refer to Figure 7 , using the patterned mask layer 111 as a mask, the bottom silicon 100 in the cavity groove window pattern 112 is etched to form a cavity groove 107 , and the etching end point stops at the surface of the buried oxide layer 101 .

[0089] Please refer to Figure 8 , continue to use the patterned photolithography mask layer as a mask, and perform ion implantation from the bottom side of the bottom silicon layer to the preset well region position i2 of the top silicon layer to form a well region 108, wherein the preset well region position i2 corresponds to the cavity groove 107 up and down.

[0090] Specifically, since the cavity groove 107 corresponds to the preset area i1 in upper and lower parts and the size of the cavity groove window pattern 112 is larger than the size of the preset area i1, and since the preset well region position i2 corresponds to the cavity groove 107 in upper and lower parts and the size of the preset well region position i2 is larger than the size of the preset position i1, the first doped region and the second doped region are located in the well region, thereby achieving alignment of the device area of ​​the pressure sensor and ensuring the normal electrical performance of the pressure sensor.

[0091] Please refer to Fig. 9 After forming the well region 108, the mask layer 111 is removed, and thermal annealing is performed on the well region 108. The removal of the photolithography mask layer 111 and the thermal annealing of the well region 108 can refer to the third mask layer, which will not be described in detail.

[0092] The ions implanted into the well region may be P-type ions or N-type ions; the first doping region and the second doping region 10 may include P-type doping regions or N-type doping regions.

[0093] As an example, the first doping region is a high-concentration P-type doping region, the second doping region is a low-concentration P-type doping region, and the ions implanted in the well region are N-type ions.

[0094] Taking the implanted ions as N-type ions as an example, the parameters of the N-type ion implantation include: the implanted material includes at least phosphorus ions, the implanted dose is 4e 15 ions / cm 2 ~6e 15 ions / cm 2 The implantation energy is between 110KeV and 130KeV, and the implantation angle of the ions is between 6° and 8° from the vertical direction. Of course, the material, concentration, energy and implantation angle of the N-type ion implantation can be adjusted according to actual needs and are not limited here.

[0095] Since the mask layer 111 used when forming the cavity groove 107 is used as a mask for N-type ion implantation, a photomask is saved in the process of forming the well region 108, thereby reducing the manufacturing cost of the device. At the same time, the buried oxide layer 101 in the cavity groove 107 serves as a barrier layer. When ion implantation is performed, the implanted ions will be hindered by the buried oxide layer, and the position scattering of the implanted ions entering the lattice will increase, preventing the implantation from being directly aligned with the lattice gap position, and thus controlling the implantation depth of the ions.

[0096] Please refer to Fig.10 , providing a second substrate 109 , the second substrate 109 including a first surface b1 and a second surface b2 opposite to each other, and bonding the first surface b1 of the second substrate 109 and the bottom surface a2 of the bottom silicon layer 100 to form a cavity structure 110 .

[0097] Please refer to Fig.11 After forming the cavity structure 110, the second surface b2 of the second substrate 109 is thinned, and the thickness of the bonded wafer is thinned to a second preset thickness to form a pressure sensor.

[0098] Thinning the second surface b2 of the second substrate 109 includes the following steps:

[0099] The second surface b2 of the second substrate 109 is dry-etched to reduce the thickness of the bonded wafer to a second preset thickness. The specific etching gas and the pressure of the etching gas for dry-etching the second surface b2 of the second substrate 109 are referred to the above-mentioned dry-etching of the second surface of the bottom silicon layer, which will not be described in detail here. Specifically, the second preset thickness is about 700 μm.

[0100] Of course, those skilled in the art should be aware that there are many ways to thin the second substrate, and the present invention is not limited thereto.

[0101] In summary, the method for reducing the manufacturing cost of the pressure sensor provided by the embodiment of the present invention performs ion implantation on the top silicon layer by reusing the photolithography mask layer that forms the cavity groove. Therefore, in the process of preparing the N-well region, one photomask is saved, thereby reducing the preparation cost of the pressure sensor. At the same time, the buried oxide layer in the cavity groove serves as a barrier layer. When ion implantation is performed, the injected ions will be hindered by the buried oxide layer, and the position scattering of the injected ions entering the lattice will increase, preventing the injection from being directly aligned with the lattice gap position, and the injection depth of the ions can be controlled.

[0102] Please continue to refer to Figure 8 The embodiment of the present invention further provides a pressure sensor, the pressure sensor comprising a pressure sensor prepared by the above method for reducing the manufacturing cost of the pressure sensor, the pressure sensor comprising:

[0103] A first substrate, the first substrate comprising a bottom silicon layer 100, a buried oxide layer 101 and a top silicon layer 102 stacked in sequence;

[0104] A first doping region 105 and a second doping region 106, wherein the first doping region 105 and the second doping region 106 are both located in a preset region i1 of the top silicon layer 102;

[0105] A well region 108, wherein the well region 108 surrounds the first doping region 105 and the second doping region 106 and fills the preset area i1;

[0106] A cavity structure 110 is located in the bottom silicon layer 100, the cavity structure 110 and the preset area i1 are vertically opposite to each other and the buried oxide layer 101 is exposed;

[0107] The second substrate 109 is bonded to the bottom surface b2 of the bottom silicon layer 100 to form a cavity structure of the pressure sensor.

[0108] Among them, the pressure sensor structure provided by the present invention does not require an additional mask for the formation of the well region. The well region corresponds to the cavity up and down and is aligned with the first doping region and the second doping region, which improves the alignment accuracy between the cavity and the device region, saves a mask in the process of forming the well region, and thus reduces the preparation cost of the pressure sensor.

[0109] The materials, formation process, working principle, specific implementation method and beneficial effects involved in the pressure sensor structure in the embodiment of the present invention can all be found in the preparation method of the pressure sensor in the embodiment of the present invention, and will not be described in detail here.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 invention.

Claims

1. A method for preparing a pressure sensor, characterized in that: include: Providing a first substrate, comprising a bottom silicon layer, a buried oxide layer and a top silicon layer stacked in sequence; From one side of the top surface of the top silicon layer, a first doping region and a second doping region are formed in a preset area of ​​the top silicon layer; A patterned mask layer is formed on the bottom surface of the bottom silicon layer, wherein the patterned mask layer includes a cavity groove window pattern and a blocking area, wherein the cavity groove window pattern corresponds to the preset area in a vertical direction, and a size of the cavity groove window pattern is larger than a size of the preset area; Using the patterned mask layer as a mask, etching the bottom silicon in the cavity groove window pattern, with the etching endpoint staying on the surface of the buried oxide layer; Using the patterned mask layer as a mask, ion implantation is performed from the bottom side of the bottom silicon layer to a preset well region position of the top silicon layer to form a well region, wherein the preset well region position corresponds to the cavity groove up and down; A second substrate is provided, and the second substrate is bonded to the bottom surface of the bottom silicon layer of the first substrate to form a pressure sensor.

2. The method for preparing a pressure sensor according to claim 1, characterized in that: The ion implantation is N-type ion implantation, and the parameters include: the implantation material is phosphorus, the implantation dose is 4e 15 ioNs / cm 2 ~6e 15 ioNs / cm 2 The injection energy is between 110KeV and 130KeV, and the injection angle of the ions is between 6° and 8° away from the vertical direction.

3. The method for reducing the manufacturing cost of a pressure sensor according to claim 1, characterized in that: Also includes: forming an oxide layer on a surface of the top silicon layer; A first cutting mark is formed at a surface edge of the oxide layer, and the cutting mark is located outside the main body of the pressure sensor.

4. The method for preparing a pressure sensor according to claim 3, characterized in that: Before forming the cavity groove on the bottom surface of the bottom silicon layer, the method further comprises: Thinning the bottom surface of the bottom silicon layer and reducing the thickness of the first substrate to a first preset thickness; The bottom surface of the thinned bottom silicon layer is subjected to chemical mechanical polishing.

5. The method for preparing a pressure sensor according to claim 4, characterized in that: The first preset thickness is within 500 μm.

6. The method for preparing a pressure sensor according to claim 4, characterized in that: The second substrate includes a first surface and a second surface that are opposite to each other, the first surface of the second substrate is bonded to the bottom surface of the bottom silicon layer of the first substrate, and further includes: Thinning the second surface of the second substrate, and thinning the thickness of the bonded wafer to a second preset thickness; The second surface of the thinned second substrate is subjected to chemical mechanical polishing.

7. The method for preparing a pressure sensor according to claim 6, characterized in that: The second preset thickness is within 700 μm.

8. The method for reducing the manufacturing cost of a pressure sensor according to claim 3, characterized in that: Forming a first doped region in the top silicon layer specifically includes: Evenly coating the photoresist on the surface of the oxide layer; Expose, develop and bake the photoresist using a first photomask, wherein the first photomask includes a P+ doped region window pattern region and a blocking region; P+ ion implantation is performed to form a P+ doped region.

9. The method for preparing a pressure sensor according to claim 8, characterized in that: Forming a second doped region in a preset area within the top silicon layer specifically includes: The photoresist is exposed, developed and baked by using a second photomask, wherein the second photomask includes a P-doped region window pattern region and a blocking region; Performing P-ion implantation to form a P-doped region; removing the photoresist; Thermal annealing is performed to activate the impurity atoms and repair lattice damage.

10. A pressure sensor, characterized in that: A pressure sensor prepared by the method for reducing the manufacturing cost of a pressure sensor according to any one of claims 1 to 9, the pressure sensor comprising: A first substrate, the first substrate comprising a bottom silicon layer, a buried oxide layer and a top silicon layer stacked in sequence; a first doping region and a second doping region, wherein the first doping region and the second doping region are both located in the top silicon layer region; a well region, wherein the well region surrounds the first doped region and the second doped region and completely fills the preset area; A cavity groove is located in the bottom silicon layer, the cavity groove and the preset area are vertically opposite to each other and the buried oxide layer is exposed; A second substrate is bonded to the bottom surface of the bottom silicon layer to form a cavity structure of the pressure sensor.

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