Pressure sensor and method for manufacturing the same

Abstract

The present invention relates to a pressure sensor and a manufacturing method thereof. The pressure sensor comprises a substrate structure and a top structure. The top structure comprises a first silicon layer, a first insulating layer arranged on the back of the first silicon layer, a piezoresistive layer arranged on the back of the first insulating layer, a top first lower insulating layer arranged on the front of the first silicon layer, a thick semiconductor material layer formed on the front of the top first lower insulating layer, and a top second lower insulating layer covering the thick semiconductor material layer; the first silicon layer is used as a pressure sensitive film; the thick semiconductor material layer is used as an island structure; the piezoresistive layer comprises at least one piezoresistor; the upper surface of the substrate structure is recessed downward to form a bonding groove, and the thick semiconductor material layer is bonded in the bonding groove and forms a gap with the bonding groove. The pressure sensor forms a thick semiconductor material layer used as an island structure on the front of the first silicon layer, so as to achieve the purpose of effectively controlling the thickness consistency and plane size consistency of the pressure sensitive film.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, and in particular to a pressure sensor and a manufacturing method thereof. Background Art

[0002] With the rise of industries such as the Internet of Things, MEMS (Micro Electro Mechanical Systems) sensors have great application prospects due to their small size, low power consumption, light weight and fast response, etc. MEMS pressure sensors, in particular, have great applications in automotive electronics, consumer products and industrial control.

[0003] Traditional MEMS pressure sensors are mostly based on traditional single-layer SOI wafers that use backside wet etching to etch the sensitive film and back island structure. The thickness of the sensitive film is determined by the wet etching rate and etching time. However, wet etching of silicon is usually operated by heating (85°C) KOH solution or TMAH solution. During the heating process, due to the evaporation of water and the reaction of the etching solution with silicon, the concentration of KOH or TMAH solution will change as the reaction time continues, so it is difficult to accurately control the etching depth. At the same time, due to the anisotropy of silicon, when KOH or TMAH is used to wet-etch the silicon substrate from the back, the opening pattern will inevitably produce a trapezoidal pattern with a small top and a large bottom cross-section. This makes the plane size of the product itself much larger than the actual required plane size of the pressure sensitive film, and the product is difficult to miniaturize.

[0004] In order to avoid the problem of enlarged size caused by the anisotropic wet etching of silicon mentioned above, the prior art adopts dry etching technology of silicon based on traditional single-layer SOI wafers. In theory, deep reactive ion etching of silicon can make the side of the etching pattern close to 90°, which can reduce the planar size of the chip opening and avoid the problem of too large back-etching opening. However, in the actual process, it is difficult to ensure the consistency of the etching angle by deep reactive ion etching of silicon. For 8-inch wafers, the industry can generally only guarantee an etching accuracy of 82°-92°. Considering the problems of lateral etching, the alignment and etching compensation of the top piezoresistive structure and the back island by deep reactive ion etching of silicon is very complicated. In theory, only when the piezoresistive structure is aligned with the boundary (stress concentration point) of the back island can the performance of the pressure sensor (such as sensitivity, nonlinearity and pressure overload resistance, etc.) be guaranteed. Once there is a deviation, the performance change of the pressure sensor will deviate greatly from the design value. In addition, since the traditional single-layer SOI wafer is used, the etching depth is still determined by the etching rate and etching time, and the etching depth consistency is low.

[0005] In response to the above problems, the prior art also uses a double-layer SOI wafer (DSOI) for back etching to realize pressure sensor manufacturing. When deep reactive ion etching is performed on the back side, the etching can stop at the silicon oxide by itself by utilizing the high selectivity of silicon and silicon oxide, which can solve the problem of etching depth consistency relatively well. However, the charged ions etched will be enriched at the silicon oxide. As the over-etching time increases, a significant lateral etching effect (notching effect, also called floating effect) will be generated at the bottom of the etching, thereby affecting the plane size of the sensitive film of the pressure sensor, affecting the position alignment of the top piezoresistor and the back island, etc. In addition, due to the use of back etching, the lateral size deviation problem caused by the angle deviation of the side of deep reactive ion etching cannot be solved (etching 500um, even if the angle deviation is 1°, it will produce a lateral deviation of 500um×tan1°=9um). Summary of the invention

[0006] Based on this, the present invention provides a pressure sensor and a method for manufacturing the same, forming a thick semiconductor material layer serving as an island structure on the front side of a first silicon layer, so as to effectively control the thickness consistency and planar size consistency of the pressure sensitive film.

[0007] A pressure sensor comprises a substrate structure and a top structure, wherein the top structure comprises a first silicon layer, a first insulating layer arranged on the back of the first silicon layer, a piezoresistive layer arranged on the back of the first insulating layer, a top first lower insulating layer arranged on the front of the first silicon layer, a thick semiconductor material layer formed on the front of the top first lower insulating layer, and a top second lower insulating layer covering the thick semiconductor material layer; the first silicon layer is used as a pressure sensitive film; the thick semiconductor material layer is used as an island structure; the piezoresistive layer comprises at least one piezoresistor;

[0008] The upper surface of the substrate structure is recessed downward to form a bonding groove, and the thick semiconductor material layer is bonded in the bonding groove and forms a gap with the bonding groove.

[0009] The above-mentioned pressure sensor has a thick semiconductor material layer used as an island structure formed on the front side of the first silicon layer. The thick semiconductor material layer is bonded to the bonding groove of the substrate structure and forms a gap with the bonding groove. This can effectively control the thickness consistency and planar size consistency of the pressure sensitive film (i.e., the first silicon layer), and can also utilize the front pressure sensing technology of the pressure sensitive film to avoid the occurrence of air leakage or the phenomenon that the sealing material is pushed away by high pressure. At the same time, it can reduce the nonlinearity of the pressure sensitive film and increase the range of measurable pressure.

[0010] In one embodiment, the top structure further includes a top insulating layer disposed on the back of the first insulating layer and covering the piezoresistive layer, and a conductive contact hole for exposing the piezoresistive layer is disposed on the top insulating layer, and the conductive contact hole is used to partially expose the piezoresistive layer from the top insulating layer;

[0011] The pressure sensor also includes a metal block which is correspondingly arranged at the conductive contact hole and is electrically connected to the piezoresistive layer.

[0012] In one of the embodiments, each of the piezoresistor is correspondingly provided with at least one of the conductive contact holes, and each of the conductive contact holes is correspondingly provided with at least one of the metal blocks.

[0013] In one embodiment, the piezoresistors are provided in plurality, and the piezoresistive layer further comprises a conductive connection line for connecting the plurality of the piezoresistors;

[0014] Each of the piezoresistors or each of the conductive connecting lines is correspondingly provided with at least one of the conductive contact holes, and each of the conductive contact holes is correspondingly provided with at least one of the metal blocks.

[0015] In one of the embodiments, an air inlet penetrating the substrate structure is formed on the substrate structure, and the air inlet is communicated with the bottom of the bonding groove.

[0016] The present invention also provides a method for manufacturing a pressure sensor, which comprises the following steps: S1, selecting a first silicon wafer, and growing a front insulating layer and a back insulating layer on the front and back of the first silicon wafer, respectively; the first silicon wafer is a wafer having a silicon structure on a double insulating layer (DSOI), the first silicon wafer comprises a first silicon layer, a first insulating layer, a second silicon layer, a second insulating layer and a third silicon layer which are sequentially stacked and covered, and a surface of the first silicon layer facing away from the third silicon layer is the front of the first silicon layer;

[0017] S2, forming a thick semiconductor material layer serving as an island structure on the front side of the first silicon layer;

[0018] S3, removing the front insulating layer grown in S1, and regenerating a top first lower insulating layer on the front of the first silicon wafer, and regenerating a top second lower insulating layer covering the thick semiconductor material layer on the front of the first silicon wafer, to obtain a top initial structure;

[0019] S4, forming a substrate structure, wherein a bonding groove is formed on the substrate structure;

[0020] S5, inverting the top preliminary structure, and bonding the thick semiconductor material layer in the bonding groove, so that a gap is formed between the thick semiconductor material layer and the bonding groove;

[0021] S6, removing redundant layer structures, including: removing the back insulating layer, the third silicon layer and the second insulating layer of the top primary structure;

[0022] S7, doping the second silicon layer, and patterning the doped second silicon layer to form a piezoresistive layer, wherein the piezoresistive layer is formed with at least one piezoresistor;

[0023] S8. Obtain a pressure sensor.

[0024] In one embodiment, in S7, after forming the piezoresistive layer, the step further includes:

[0025] Patterning the top insulating layer to form a conductive contact hole; wherein the conductive contact hole is used to expose a portion of the piezoresistive layer from the top insulating layer;

[0026] A metal block electrically connected to the piezoresistive layer is formed at the conductive contact hole.

[0027] In one of the embodiments, each of the piezoresistors is correspondingly formed with at least one of the conductive contact holes, and each of the conductive contact holes is correspondingly formed with at least one of the metal blocks.

[0028] In one of the embodiments, in S7, the piezoresistive layer is further formed with conductive connecting lines for connecting a plurality of the piezoresistors;

[0029] At least one conductive contact hole is formed correspondingly to each piezoresistor or each conductive connection line, and at least one metal block is formed correspondingly to each conductive contact hole.

[0030] In one embodiment, after S7, the method further includes:

[0031] An air inlet penetrating the substrate structure is formed on the substrate structure, and the air inlet is communicated with the bottom of the bonding groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic longitudinal cross-sectional view of a pressure sensor according to an embodiment of the present invention;

[0033] Figures 2 to 13 for Figure 1 The process flow diagram of the pressure sensor is shown. DETAILED DESCRIPTION

[0034] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0035] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0037] like Figure 1 As shown, it is a pressure sensor made based on a wafer with a double-layer "silicon on insulating layer" structure (Double-SOI, DSOI) according to an embodiment of the present invention, and the pressure sensor includes: a substrate 1 structure and a top structure 2, the top structure 2 includes a first silicon layer 21, a first insulating layer 22 arranged on the back of the first silicon layer 21, a piezoresistive layer 231 arranged on the back of the first insulating layer 22, a top first lower insulating layer 24 arranged on the front of the first silicon layer 21, a thick semiconductor material layer 25 formed on the front of the top first lower insulating layer 24, and a top second lower insulating layer 26 covering the thick semiconductor material layer 25; the first silicon layer 21 is used as a pressure sensitive film; the thick semiconductor material layer 25 is used as an island structure; the piezoresistive layer 231 includes at least one piezoresistor 2311.

[0038] The upper surface of the substrate structure 1 is recessed downward to form a bonding groove 10 , and the thick semiconductor material layer 25 is bonded in the bonding groove 10 and forms a gap with the bonding groove.

[0039] In the pressure sensor 1, a thick semiconductor material layer 25 serving as an island structure is formed on the front side of the first silicon layer 21. The thick semiconductor material layer 25 is bonded to the bonding groove 10 of the substrate structure 1 and forms a gap with the bonding groove 10. This can effectively control the thickness consistency and planar size consistency of the pressure sensitive film (i.e., the first silicon layer 21), and can also utilize the front side pressure sensing technology of the pressure sensitive film to avoid the sealing material from leaking or being pushed away by high pressure. At the same time, it can reduce the nonlinearity of the pressure sensitive film and increase the range of measurable pressure.

[0040] The pressure sensor of the embodiment of the present invention adopts a DSOI wafer, and the first silicon layer 21 of the DSOI wafer is used as a pressure sensitive film, and its thickness consistency is good. The lateral size of the pressure sensitive film is determined by the size of the bonding groove 10 of the substrate structure 1. Compared with the back-opening method in the prior art, its lateral size is easy to control. In addition, by utilizing the characteristics of the SOI wafer, the piezoresistive structure has no PN junction and can work at high temperatures (generally greater than 150 degrees).

[0041] In one embodiment, Figure 1 As shown, the doping type of the first silicon layer 21 can be freely selected according to actual needs, so that the pressure sensor can improve the stability of the sensor output under high temperature (generally greater than 150 degrees) conditions, reduce the failure rate of the pressure sensor, and enable the pressure sensor to work in an environment higher than 150 degrees. In a specific embodiment, the first silicon layer 21 is N-type doped.

[0042] In one embodiment, Figure 1 As shown, the first insulating layer 22 is a silicon oxide layer.

[0043] In one embodiment, Figure 1 As shown, the conductive semiconductor material layer 25 is made of polysilicon material to achieve electrical conduction of the internal circuit of the pressure sensor.

[0044] In one embodiment, Figure 1 As shown, the top structure 2 also includes a top upper insulating layer 27 disposed on the back of the first insulating layer 22 and covering the piezoresistive layer 231, and a conductive contact hole 271 corresponding to the piezoresistive layer 231 is disposed on the top upper insulating layer 27, and the conductive contact hole 271 is used to expose part of the piezoresistive layer 231 from the top upper insulating layer 27. The conductive contact hole 271 is provided to energize the pressure sensor. It should be noted that the number of the conductive contact holes 271 can be one or more.

[0045] In one embodiment, Figure 1 As shown, the pressure sensor further includes a metal block 3 disposed at the conductive contact hole 271 and electrically connected to the piezoresistive layer 231 , so as to facilitate the power supply of the pressure sensor.

[0046] In a specific embodiment, if Figure 1 As shown, each of the piezoresistors 2311 is correspondingly provided with at least one of the conductive contact holes 271 , and each of the conductive contact holes 271 is correspondingly provided with at least one of the metal blocks 3 .

[0047] like Figure 1In the illustrated embodiment, two piezoresistors 2311 are provided, each of which corresponds to one conductive contact hole 271, and each of which corresponds to one metal block 3. The two piezoresistors 2311 are first electrically isolated by the top insulating layer 27, and then electrically connected complementary by the upper metal block 3. At this time, the metal block 3 not only serves as a connecting line to electrically connect the two piezoresistors 2311, but also provides the function of a wire pad for subsequent wire-bonding.

[0048] In an embodiment not shown in the figure, if there are still multiple piezoresistors, the piezoresistive layer will also include a conductive connection line for connecting the multiple piezoresistors, and each piezoresistors is correspondingly provided with at least one conductive contact hole, and each conductive contact hole is correspondingly provided with at least one metal block. At this time, the piezoresistors are connected to each other through conductive connection lines, and the subsequent metal blocks only function as wire-bonding pads.

[0049] In another embodiment not shown in the figure, if there are still multiple piezoresistors, the piezoresistive layer will also include conductive connecting wires for connecting the multiple piezoresistors, and each of the conductive connecting wires is correspondingly provided with at least one conductive contact hole, and each of the conductive contact holes is correspondingly provided with at least one metal block. At this time, the piezoresistors are connected to each other through conductive connecting wires, but at the same time, there are metal blocks on the conductive connecting wires, which can further reduce the resistance of the conductive connecting wires. Finally, the metal blocks will also provide the function of wire-bonding pads.

[0050] In one embodiment, Figure 1 As shown, the substrate structure 1 includes a middle silicon material layer 11 and an upper substrate insulating layer 12 formed on the upper surface of the middle silicon material layer 11 .

[0051] In one embodiment, Figure 1 As shown, for a pressure sensor that requires gauge pressure or differential pressure, an air inlet 100 that passes through the substrate structure 1 can be formed on the substrate structure 1, and the air inlet 100 is connected to the bottom of the bonding slot 10 to meet the structural requirements of a pressure sensor that requires gauge pressure or differential pressure.

[0052] like Figures 2 to 13 As shown, it is a method for manufacturing a pressure sensor according to an embodiment of the present invention, which comprises the steps of:

[0053] S1, select Figure 2 The first silicon wafer a is shown, and a front insulating layer 201 and a back insulating layer 202 are grown on the front and back of the first silicon wafer a respectively (as shown in FIG. Figure 3 ).like Figure 2 As shown, the first silicon wafer a is a wafer with a double-layer "silicon on insulating layer" structure (Double-SOI, DSOI), and the first silicon wafer a includes a first silicon layer 21, a first insulating layer 22, a second silicon layer 23, a second insulating layer 28 and a third silicon layer 29 stacked in sequence, and the surface of the first silicon layer 21 facing away from the third silicon layer 29 is the front side of the first silicon layer 21, that is, the front side of the first silicon wafer a.

[0054] Preferably, the first silicon layer 21, the second silicon layer 23 and the third silicon layer 29 are doped with the same type, so that the pressure sensor can improve the stability of the sensor output under high temperature (generally greater than 150 degrees) conditions, reduce the probability of failure of the pressure sensor, and enable the pressure sensor to work in an environment higher than 150°C. Furthermore, the doping concentration and crystal orientation of the first silicon layer 21, the second silicon layer 23 and the third silicon layer 29 can be freely selected according to actual needs. In this embodiment, the first silicon layer 21, the second silicon layer 23 and the third silicon layer 29 all adopt (100) crystal orientation and N-type doping.

[0055] Furthermore, the first insulating layer 22 and the second insulating layer 28 are both silicon oxide layers.

[0056] S2, forming a thick semiconductor material layer 25 (such as Figure 4 ).

[0057] Specifically, in step S2, the thick semiconductor material layer 25 is formed by:

[0058] First, thick semiconductor materials (such as Figure 3 ), such as epitaxially grown polysilicon material. The thickness of the thick semiconductor material can be processed according to the design requirements of the pressure sensor.

[0059] Then, the thick semiconductor material on the back side of the first silicon wafer a is etched away, and the thick semiconductor material on the front side of the first silicon wafer a is patterned to form a thick semiconductor material layer 25 serving as an island structure.

[0060] S3, remove the front insulating layer 201 grown in S1, and regenerate the top first lower insulating layer 24 on the front of the first silicon wafer a, and regenerate the top second lower insulating layer 26 (such as the top second lower insulating layer 26) covering the thick semiconductor material layer 25 on the front of the first silicon wafer a. Figure 5 ), and obtain the top layer initial structure. Preferably, the top layer first lower insulating layer 24 and the top layer second lower insulating layer 26 are both made of silicon oxide material.

[0061] The top layer first lower insulating layer 24 is partially connected to the top layer second lower insulating layer 26 to form a whole top layer lower insulating layer.

[0062] S4, forming a substrate structure 1, wherein a bonding groove 10 is formed on the substrate structure 1.

[0063] Specifically, in step S4, the substrate structure 1 is formed by:

[0064] First, a second silicon wafer b is selected and used as the middle silicon material layer 11 , and a substrate insulating layer 101 is formed on the upper surface and the lower surface of the second silicon wafer 11 .

[0065] Then, the second silicon wafer b and the substrate insulating layer 101 formed on the upper surface of the second silicon wafer b are patterned to form the bonding groove 10 (eg Figure 6 ).

[0066] Afterwards, the substrate insulating layer 101 on the upper surface of the second silicon wafer b is removed, and a substrate upper insulating layer 12 (such as Figure 7 ), and obtain the substrate structure 1.

[0067] S5, such as Figure 8 As shown, the top preliminary structure is inverted, and the thick semiconductor material layer 25 is bonded in the bonding groove 10 , and a gap is formed between the thick semiconductor material layer 25 and the bonding groove 10 .

[0068] S6. Remove unnecessary layers of structure.

[0069] Specifically, in step S6, removing the redundant layer structure includes:

[0070] The back insulating layer 202, the third silicon layer 29 and the second insulating layer 28 of the top structure are removed; the substrate insulating layer 101 formed on the lower surface of the second silicon wafer b is removed (such as Fig. 9 ).

[0071] S7, doping the second silicon layer 23 (such as Fig.10 ), and patterning the doped second silicon layer 23 to form a piezoresistive layer 231, wherein the piezoresistive layer 231 is formed with at least one piezoresistor 2311, and a top structure 2 (such as Fig.11 ).

[0072] The doping elements, concentration and doping process of the second silicon layer 23 can be selected as needed. A typical method is to perform boron ion implantation and adopt high temperature annealing to uniformly dope the second silicon layer 22 to a doping concentration greater than 1E20cm-3 .

[0073] In one embodiment, in S7, after forming the piezoresistive layer 231, the following steps are included:

[0074] First, a top insulating layer 27 covering the piezoresistive layer 231 is deposited on the back of the first insulating layer 22. The piezoresistive layer 231 is protected by depositing the top insulating layer 27 on the back of the first insulating layer 22. Preferably, the top insulating layer 27 is made of plasma enhanced chemical vapor deposition (PECVD) silicon oxide.

[0075] Then, the top insulating layer 27 is patterned to form a conductive contact hole 271 ; wherein the conductive contact hole 271 is used to expose a portion of the piezoresistive layer 231 from the top insulating layer 27 so as to energize the pressure sensor.

[0076] After the conductive contact hole 271 is formed, a metal block 3 electrically connected to the piezoresistive layer 231 may be formed at the conductive contact hole 271. Preferably, the metal block 3 may be formed by depositing a high temperature resistant conductive metal Pad and patterning it.

[0077] Preferably, each of the piezoresistors 2311 is correspondingly formed with at least one of the conductive contact holes 271 , and each of the conductive contact holes 271 is correspondingly formed with at least one of the metal blocks 3 .

[0078] In other embodiments not shown in the figure, if the piezoresistors are provided in plurality, then in S7, the piezoresistive layer may further be formed with conductive connection lines for connecting the plurality of piezoresistors. Each piezoresistor or each conductive connection line is correspondingly formed with at least one conductive contact hole, and each conductive contact hole is correspondingly formed with at least one metal block.

[0079] If the conductive contact hole is formed corresponding to the piezoresistance, the metal block only functions as a wire-bonding pad. If the conductive contact hole is formed corresponding to the conductive connection line, the resistance of the conductive connection line can be further reduced, and at the same time, the metal block will also provide the function of a wire-bonding pad.

[0080] S8. Obtain a pressure sensor.

[0081] It should be noted that, in the actual production process, the completion of the above steps S1-S8 is used to obtain an absolute pressure type pressure sensor.

[0082] In the actual production process, if a gauge pressure or differential pressure type pressure sensor is required, it is only necessary to add the following steps after S7:

[0083] An air inlet 100 penetrating the substrate structure 1 is formed on the substrate structure 1 , and the air inlet 100 is communicated with the bottom of the bonding groove 10 .

[0084] Specifically, the air inlet 100 formed to penetrate the substrate structure 1 includes:

[0085] First, a first through hole 110 is etched on the middle silicon material layer 11 using deep reactive ions of silicon, and the etching is stopped at the bottom surface of the insulating layer 12 on the substrate (such as Fig.12 ).

[0086] Then, the position on the insulating layer 12 on the substrate corresponding to the first through hole 110 is removed to form a second through hole 120. The first through hole 110 is connected to the second through hole 120 to obtain the air inlet 100 (such as Fig.13 ).

[0087] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A pressure sensor, characterized in that: The invention comprises a substrate structure and a top structure, wherein the top structure comprises a first silicon layer, a first insulating layer arranged on the back of the first silicon layer, a piezoresistive layer arranged on the back of the first insulating layer, a top first lower insulating layer arranged on the front of the first silicon layer, a thick semiconductor material layer formed on the front of the top first lower insulating layer, and a top second lower insulating layer covering the thick semiconductor material layer; The first silicon layer is used as a pressure sensitive membrane; The thick semiconductor material layer is used as an island structure; the piezoresistive layer includes at least one piezoresistor; The substrate structure also includes a middle silicon material layer and an upper substrate insulating layer formed on the upper surface of the middle silicon material layer; The upper surface of the substrate structure is recessed downward to form a bonding groove, and the thick semiconductor material layer is bonded in the bonding groove and forms a gap with the bonding groove.

2. The pressure sensor according to claim 1, characterized in that: The top structure further comprises a top upper insulating layer disposed on the back of the first insulating layer and covering the piezoresistive layer, wherein the top upper insulating layer is provided with a conductive contact hole corresponding to the piezoresistive layer, and the conductive contact hole is used to expose a portion of the piezoresistive layer from the top upper insulating layer; The pressure sensor further includes a metal block which is arranged corresponding to the conductive contact hole and is electrically connected to the piezoresistance.

3. The pressure sensor according to claim 2, characterized in that: Each of the piezoresistors is correspondingly provided with at least one of the conductive contact holes, and each of the conductive contact holes is correspondingly provided with at least one of the metal blocks.

4. The pressure sensor according to claim 2, characterized in that: The piezoresistors are provided in plurality, and the piezoresistors layer further comprises conductive connecting wires for connecting the plurality of piezoresistors; Each of the piezoresistors or each of the conductive connecting lines is correspondingly provided with at least one of the conductive contact holes, and each of the conductive contact holes is correspondingly provided with at least one of the metal blocks.

5. The pressure sensor according to claim 1, characterized in that: An air inlet penetrating through the substrate structure is formed on the substrate structure, and the air inlet is communicated with the bottom of the bonding groove.

6. A method for manufacturing a pressure sensor, characterized in that: Includes steps: S1. Select a first silicon wafer, and grow a front insulating layer and a back insulating layer on the front and back of the first silicon wafer, respectively; the first silicon wafer is a wafer with a silicon structure on a double insulating layer (DSOI), the first silicon wafer includes a first silicon layer, a first insulating layer, a second silicon layer, a second insulating layer and a third silicon layer stacked in sequence, and a surface of the first silicon layer facing away from the third silicon layer is the front of the first silicon layer; S2, forming a thick semiconductor material layer serving as an island structure on the front side of the first silicon layer; S3, removing the front insulating layer grown in S1, and regenerating a top first lower insulating layer on the front of the first silicon wafer, and regenerating a top second lower insulating layer covering the thick semiconductor material layer on the front of the first silicon wafer, to obtain a top initial structure; S4, forming a substrate structure, wherein a bonding groove is formed on the substrate structure; S5, inverting the top preliminary structure, and bonding the thick semiconductor material layer in the bonding groove, so that a gap is formed between the thick semiconductor material layer and the bonding groove; S6, removing redundant layer structures, including: removing the back insulating layer, the third silicon layer and the second insulating layer of the top primary structure; S7, doping the second silicon layer, and patterning the doped second silicon layer to form a piezoresistive layer, wherein the piezoresistive layer is formed with at least one piezoresistor; S8. Obtain a pressure sensor.

7. The method for manufacturing a pressure sensor according to claim 6, characterized in that: In the S7, after the piezoresistive layer is formed, the step further includes: Depositing a top insulating layer covering the piezoresistive layer on the back side of the first insulating layer; Patterning the top insulating layer to form a conductive contact hole; wherein the conductive contact hole is used to expose a portion of the piezoresistive layer from the top insulating layer; A metal block electrically connected to the piezoresistive layer is formed at the conductive contact hole.

8. The method for manufacturing a pressure sensor according to claim 7, characterized in that: At least one conductive contact hole is formed corresponding to each of the piezoresistors, and at least one metal block is formed corresponding to each of the conductive contact holes.

9. The method for manufacturing a pressure sensor according to claim 7, characterized in that: The piezoresistance is provided in plurality; In the step S7, the piezoresistive layer is further formed with conductive connecting lines for connecting a plurality of the piezoresistors; At least one conductive contact hole is formed correspondingly to each piezoresistor or each conductive connection line, and at least one metal block is formed correspondingly to each conductive contact hole.

10. The method for manufacturing a pressure sensor according to claim 7, characterized in that: After S7, the following further includes: An air inlet penetrating the substrate structure is formed on the substrate structure, and the air inlet is communicated with the bottom of the bonding groove.

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