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, a top structure and a sensitive film layer 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 and a top first lower insulating layer arranged on the front of the first silicon layer; a deposition hole and a beam hole penetrating the top first lower insulating layer, the first silicon layer and the first insulating layer are formed on the top structure, and a hole wall insulating layer is formed on the hole wall of the deposition hole; the upper surface of the substrate structure is recessed downward to form a bonding groove, the top structure is inverted on the substrate structure, the front of the top first lower insulating layer faces the substrate structure, and the deposition hole is connected with the bonding groove; the sensitive film layer structure is formed on the inner wall of the hole wall insulating layer and extends downward to cover the inner wall of the bonding groove and the lower surface of the top structure. The pressure sensor forms a beam-film stress concentration structure to achieve the purpose of measuring micro pressure.

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. In particular, MEMS pressure sensors have great applications in automotive electronics, consumer products and industrial control. At present, MEMS pressure sensors are mostly made of ordinary double-sided polished wafers or single-layer SOI wafers.

[0003] For pressure sensors made of ordinary double-sided polished wafers, although the "beam-membrane-island" stress concentration structure can be formed at the same time, its piezoresistor can only use a PN junction type to achieve mutual electrical isolation, which limits the operating temperature range and cannot meet the measurement requirements at an ambient temperature greater than 150°C. In addition, in the prior art, the thickness of the beam, membrane and island structure of the pressure sensor made of ordinary double-sided polished wafers is determined by the etching depth, which depends on the etching rate and etching time, and it is difficult to ensure the consistency of batch processed devices.

[0004] For pressure sensors made of single-layer SOI wafers, in order to meet the requirements of high-temperature measurement, the top silicon of the SOI wafer is used as a piezoresistor, and physical isolation is used to achieve high-temperature measurement. However, although this method meets the requirements of high-temperature testing, it cannot process the beam structure and can only use the "membrane-island" single stress concentration structure. Compared with the "beam-membrane-island" double stress concentration structure, the sensitivity of the device is reduced. Summary of the invention

[0005] Based on this, the present invention provides a pressure sensor and a manufacturing method thereof, forming a beam-membrane stress concentration structure to achieve the purpose of measuring tiny pressures.

[0006] A pressure sensor, comprising a substrate structure, a top structure and a sensitive film layer 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, and a top first lower insulating layer arranged on the front of the first silicon layer; a deposition hole and a beam hole penetrating the top first lower insulating layer, the first silicon layer and the first insulating layer are formed on the top structure, and a hole wall insulating layer is formed on the hole wall of the deposition hole;

[0007] The upper surface of the substrate structure is recessed downward to form a bonding groove, the top structure is inverted on the substrate structure, the front side of the top first lower insulating layer faces the substrate structure, and the deposition hole is connected to the bonding groove;

[0008] The sensitive film layer structure is formed on the inner wall of the hole wall insulating layer and extends downward to cover the inner wall of the bonding groove and the lower surface of the top structure.

[0009] The above-mentioned pressure sensor uses the first silicon layer as the "beam" layer in the beam-membrane stress concentration structure, and utilizes the sensitive film layer structure formed on the inner wall of the hole wall insulating layer and extending downward to cover the inner wall of the bonding groove and the lower surface of the top structure to make the "membrane" layer in the beam-membrane stress concentration structure. The pressure sensor can process a thin pressure-sensitive film to measure tiny pressures, and at the same time make good use of the characteristics of the wafer, so that the piezoresistive structure (piezoresistive layer) has no PN junction and can work at high temperatures (greater than 150°C).

[0010] In one embodiment, the sensitive film layer structure includes a pressure-sensitive film and a sensitive film insulating layer. The pressure-sensitive film is formed on the inner wall of the hole wall insulating layer and extends downward to cover the inner wall of the bonding groove and the lower surface of the top structure. The sensitive film insulating layer is formed on the pressure-sensitive film and covers the pressure-sensitive film.

[0011] In one of the embodiments, the top structure also includes a thick semiconductor material layer formed on the front side of the top first lower insulating layer and a top second lower insulating layer covering the thick semiconductor material layer, and the thick semiconductor material layer is used as an island structure; the thick semiconductor material layer is bonded in the bonding groove and forms a gap with the bonding groove.

[0012] In one of the embodiments, the top structure further includes an insulating protection layer deposited on the upper surface of the first insulating layer and covering the piezoresistive layer, and at least one conductive contact hole corresponding to the piezoresistive layer is formed on the insulating protection layer;

[0013] The pressure sensor further includes a metal block correspondingly arranged at the conductive contact hole and electrically connected to the piezoresistive layer, and each conductive contact hole is correspondingly provided with at least one metal block.

[0014] In one of the embodiments, an air inlet penetrating the substrate structure and the sensitive film layer structure is formed on the pressure sensor, and the air inlet is communicated with the inner cavity of the bonding groove.

[0015] The present invention also provides a method for manufacturing a pressure sensor, which comprises the steps of:

[0016] S1. Select a first silicon wafer, and grow a top layer and a first lower insulating layer on the front side of the first silicon wafer to obtain a top layer initial structure; the first silicon wafer is a wafer having a silicon structure on a double insulating layer (Double-SOI, DSOI), and 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 which are sequentially stacked and covered, and a surface of the first silicon layer facing away from the third silicon layer is a front side of the first silicon layer;

[0017] S2, forming a substrate structure, wherein a bonding groove and an insulating layer on the substrate are formed on the substrate structure;

[0018] S3, invertingly bonding the top primary structure to the substrate structure, so that the front side of the top first lower insulating layer faces the substrate structure;

[0019] S4, removing redundant layer structures, including: removing the back insulating layer, the third silicon layer and the second insulating layer of the top primary structure;

[0020] S5, patterning the top first lower insulating layer, the first silicon layer, the first insulating layer and the second silicon layer to form a deposition hole penetrating the top first lower insulating layer, the first silicon layer, the first insulating layer and the second silicon layer, and depositing a hole wall insulating layer on the hole wall of the deposition hole;

[0021] S6, depositing to form a sensitive film layer structure, wherein the sensitive film layer structure extends downward from the inner wall of the hole wall insulating layer and covers the inner wall of the bonding groove and the lower surface of the top structure;

[0022] S7, doping the second silicon layer, and patterning the doped second silicon layer to form a piezoresistive layer;

[0023] S8, etching the top layer, the first lower insulating layer, the first silicon layer and the first insulating layer to form a beam hole;

[0024] S9. Obtain a pressure sensor.

[0025] In one embodiment, in S6, the step of depositing to form a sensitive film layer structure includes:

[0026] Depositing a sensitive film material, so that the sensitive film material is deposited on the inner wall of the hole wall insulating layer, the inner wall of the bonding groove, the lower surface of the top structure and the upper surface of the top structure;

[0027] growing an insulating material covering the pressure sensitive film on the pressure sensitive film;

[0028] The sensitive film material and the insulating material on the second silicon layer are removed to obtain a pressure sensitive film composed of the remaining sensitive film material and a sensitive film insulating layer composed of the remaining insulating material, thereby obtaining the sensitive film layer structure.

[0029] In one embodiment, the S1 further includes:

[0030] forming a thick semiconductor material layer serving as an island structure on the front side of the first silicon wafer;

[0031] A top second lower insulating layer covering the thick semiconductor material layer is generated on the front side of the first silicon wafer.

[0032] In one embodiment, after S8 and before S9, the method further includes:

[0033] Depositing an insulating protective layer covering the piezoresistive layer on the upper surface of the first insulating layer;

[0034] Patterning the insulating protection layer to form a conductive contact hole corresponding to the piezoresistive layer;

[0035] A metal block electrically conducting the piezoresistive layer is formed at the conductive contact hole.

[0036] In one embodiment, after S8 and before S9, the method further includes:

[0037] An air inlet penetrating the substrate structure and the sensitive film layer structure is formed on the pressure sensor, and the air inlet is communicated with the inner cavity of the bonding groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic longitudinal cross-sectional view of a pressure sensor according to a first embodiment of the present invention;

[0039] Figures 2 to 17 for Figure 1 The process flow diagram of the pressure sensor shown;

[0040] Fig.18 is a longitudinal cross-sectional schematic diagram of a pressure sensor according to a second embodiment of the present invention;

[0041] Fig.19 FIG. 4 is a schematic longitudinal cross-sectional view of a pressure sensor according to Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Embodiment 1

[0046] 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 structure 1, a top structure 2 and a sensitive film layer structure 3, 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; a deposition hole 201 and a beam hole 202 penetrating the top first lower insulating layer 24, the first silicon layer 21 and the first insulating layer 22 are formed on the top structure 2, and a hole wall insulating layer 27 is formed on the hole wall of the deposition hole 201.

[0047] The upper surface of the substrate structure 1 is recessed downward to form a bonding groove 10 , the top structure 2 is inverted on the substrate structure 1 , the front side of the top first lower insulating layer 24 faces the substrate structure 1 , and the deposition hole 201 is connected to the bonding groove 10 .

[0048] The sensitive film layer structure 3 is formed on the inner wall of the hole wall insulating layer 27 and extends downward to cover the inner wall of the bonding groove 10 and the lower surface of the top structure 2. It can be understood that the sensitive film layer structure 3 covers the lower surface of the top structure 2 specifically means that the sensitive film layer structure 3 covers the thick semiconductor material layer 25, and if the lower surface of the top first lower insulating layer 24 corresponding to the bonding groove 10 is partially exposed to the exposed portion of the thick semiconductor material layer 25 and the top second lower insulating layer 26, the sensitive film layer structure 3 will also cover the exposed portion.

[0049] The pressure sensor uses the first silicon layer 21 as the "beam" layer in the beam-membrane-island stress concentration structure, uses the sensitive film layer structure 3 formed on the inner wall of the hole wall insulation layer 27 and extending downward and covering the inner wall of the bonding groove 10 and the lower surface of the top structure 2 as the "membrane" layer in the beam-membrane-island stress concentration structure, and uses the thick semiconductor material layer 25 formed on the front of the top first lower insulation layer 24 as the "island" layer in the beam-membrane-island stress concentration structure. The pressure sensor can process a thin pressure sensitive film to measure tiny pressures, and at the same time, it makes good use of the characteristics of the wafer, so that the piezoresistive structure (piezoresistive layer 231) has no PN junction and can withstand high temperature (greater than 150°C) operation.

[0050] 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.

[0051] In one embodiment, Figure 1 As shown, the first insulating layer 22 is a silicon oxide layer.

[0052] In one embodiment, Figure 1 As shown, the thick semiconductor material layer 25 is made of polysilicon material to achieve electrical conduction of the internal circuit of the pressure sensor.

[0053] In one embodiment, Figure 1 As shown, the sensitive film layer structure 3 includes a pressure sensitive film 31 and a sensitive film insulating layer 32. The pressure sensitive film 31 is formed on the inner wall of the hole wall insulating layer 27 and extends downward to cover the inner wall of the bonding groove 10 and the lower surface of the top structure 2. The sensitive film insulating layer 32 is formed on the pressure sensitive film 31 and covers the pressure sensitive film 31.

[0054] In one embodiment, Figure 1 As shown, the top structure 2 also includes an insulating protection layer 28 deposited on the upper surface of the first insulating layer 22 and covering the piezoresistive layer 231, and at least one conductive contact hole 281 corresponding to the piezoresistive layer 231 is formed on the insulating protection layer 28 for powering the pressure sensor.

[0055] The pressure sensor further includes a metal block 4 correspondingly disposed at the conductive contact hole 281 and electrically connected to the piezoresistive layer 231 . Each conductive contact hole 281 is correspondingly provided with at least one metal block 4 to facilitate the power supply of the pressure sensor.

[0056] 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 .

[0057] like Figures 2 to 14 As shown, it is a method for manufacturing a pressure sensor according to an embodiment of the present invention, which comprises the steps of:

[0058] S1, select Figure 2 The first silicon wafer a shown in the figure is formed, and a top first lower insulating layer 24, a thick semiconductor material layer 25 and a top second lower insulating layer 26 are grown on the front side of the first silicon wafer a to obtain a top initial structure. 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 29 and a third silicon layer 210 stacked in sequence, and the surface of the first silicon layer 21 facing away from the third silicon layer 210 is the front side of the first silicon layer 21, that is, the front side of the first silicon wafer a.

[0059] Preferably, the first silicon layer 21, the second silicon layer 23 and the third silicon layer 210 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 failure rate 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 210 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 210 all adopt (100) crystal orientation and N-type doping.

[0060] Furthermore, the first insulating layer 23 and the second insulating layer 26 are both silicon oxide layers.

[0061] In one embodiment, in S1, growing a top first lower insulating layer 24, a thick semiconductor material layer 25, and a top second lower insulating layer 26 covering the thick semiconductor material layer 25 on the front side of the first silicon wafer a includes:

[0062] First, a front insulating layer 203 and a back insulating layer 204 are grown on the front and back of the first silicon wafer a, respectively, and 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.

[0063] Afterwards, 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 used as an island structure;

[0064] Finally, the front insulating layer 203 grown in S1 is removed, and a top first lower insulating layer 24 is regenerated on the front of the first silicon wafer a, and a top second lower insulating layer 26 (such as 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.

[0065] Preferably, the top layer first lower insulating layer 24 is partially connected to the top layer second lower insulating layer 26 to form the entire top layer lower insulating layer.

[0066] S2, forming a substrate structure 1, on which a bonding groove 10 and an insulating layer on the substrate are formed.

[0067] Specifically, in step S2, the substrate structure 1 is formed by:

[0068] 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 .

[0069] 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 ).

[0070] 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 ), to obtain the substrate structure 1.

[0071] S3, such as Figure 8 As shown, the top-layer initial structure is invertedly bonded to the substrate structure 1, so that the front side of the top-layer first lower insulating layer 24 faces the substrate structure 1, and the thick semiconductor material layer 25 is bonded in the bonding groove 10, forming a gap between the thick semiconductor material layer 25 and the bonding groove 10.

[0072] S4. Remove unnecessary layers of structure.

[0073] Specifically, in step S4, removing the redundant layer structure includes:

[0074] The back insulating layer 204, the third silicon layer 210 and the second insulating layer 29 of the top structure are removed, and the substrate insulating layer 101 formed on the lower surface of the second silicon wafer b is removed (eg Fig. 9 ).

[0075] After completing step S4 of removing the redundant layer structure, the following steps may be performed:

[0076] A first auxiliary insulating layer 205 is formed on the upper surface of the second silicon layer 23, and a second auxiliary insulating layer 102 is formed on the lower surface of the substrate structure 1. It should be noted that in other embodiments not shown in the figure, the first auxiliary insulating layer and the second auxiliary insulating layer may not be additionally provided according to actual conditions. It can be understood that if the first auxiliary insulating layer and the second auxiliary insulating layer are not provided, there is no need to remove them in the subsequent manufacturing process.

[0077] S5, patterning the top first lower insulating layer 24, the first silicon layer 21, the first insulating layer 22, the second silicon layer 23 and the first auxiliary insulating layer 205 to form a deposition hole 201 (such as Fig.10 ), and deposit a hole wall insulating layer 27 (such as Fig.11 ).

[0078] S6. Deposit to form a sensitive film layer structure 3, wherein the sensitive film layer structure extends downward from the inner wall of the hole wall insulating layer 27 and covers the inner wall of the bonding groove 10 and the lower surface of the top structure 2; wherein, the sensitive film layer structure 3 covering the lower surface of the top structure 2 specifically refers to: the sensitive film layer structure 3 covers the thick semiconductor material layer 25, if the lower surface of the top first lower insulating layer 24 corresponding to the position of the bonding groove 10 is partially exposed to the exposed portion of the thick semiconductor material layer 25 and the top second lower insulating layer 26, the sensitive film layer structure 3 will also cover the exposed portion.

[0079] In one embodiment, in S6, the step of depositing to form the sensitive film layer structure 3 includes:

[0080] First, a pressure sensitive film 31 is formed by deposition, and the pressure sensitive film 31 extends downward from the inner wall of the hole wall insulating layer 27 and covers the inner wall of the bonding groove 10 and the lower surface of the top structure 2. Preferably, the pressure sensitive film 31 can be formed by polysilicon deposition.

[0081] Then, a sensitive film insulating layer 32 covering the pressure sensitive film 31 is grown on the pressure sensitive film 31 to obtain the sensitive film layer structure 3. Preferably, the sensitive film insulating layer 32 can be formed by growing silicon oxide.

[0082] In a specific embodiment, in S6, the depositing to form the sensitive film layer structure 3 may include:

[0083] First, a sensitive film material is deposited on the inner wall of the hole wall insulating layer 27, the inner wall of the bonding groove 10, the lower surface of the top structure 2, the upper surface of the top structure 2 and the lower surface of the substrate structure 1, so that the sensitive film material covers the inner wall of the hole wall insulating layer 27, the inner wall of the bonding groove 10, the lower surface of the top structure 2, the upper surface of the top structure 2 and the lower surface of the substrate structure 1 (such as Fig.12 ).

[0084] Then, an insulating material (such as a dielectric) covering the pressure sensitive film 31 is grown on the pressure sensitive film 31. Fig.13 ).

[0085] Finally, the first auxiliary insulating layer 205, the sensitive film material and the insulating material on the second silicon layer 23 are removed, and the second auxiliary insulating layer 102, the sensitive film material and the insulating material under the substrate structure 1 are removed, so as to obtain the pressure sensitive film 31 composed of the remaining sensitive film material and the sensitive film insulating layer 32 composed of the remaining insulating material (such as Fig.14 ), and obtain the sensitive film layer structure 3.

[0086] S7, doping the second silicon layer 23 (such as Fig.15 ), and patterning the doped second silicon layer 23 to form a piezoresistive layer (such as Fig.16 ).

[0087] 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 .

[0088] It should be noted that while patterning the doped second silicon layer 23 , part of the sensitive film material of the pressure sensitive film 31 and part of the insulating material of the sensitive film insulating layer 32 on the first insulating layer 22 may also be removed.

[0089] S8 , etching the top first lower insulating layer 24 , the first silicon layer 21 and the first insulating layer 22 to form a beam hole 202 .

[0090] By forming the beam hole 202 , the first silicon layer 21 can be used as a “beam” layer in the beam-membrane-island stress concentration structure.

[0091] In the above S8, after forming the beam hole, the following steps may also be performed:

[0092] First, an insulating protection layer 28 covering the piezoresistive layer 231 is deposited on the upper surface of the first insulating layer 22. Preferably, the insulating protection layer 28 can be formed by depositing silicon nitride material.

[0093] The insulating protection layer 28 is then patterned to form a conductive contact hole 281 corresponding to the piezoresistive layer 231 ; wherein the conductive contact hole 281 is used to partially expose the piezoresistive layer 231 from the insulating protection layer 28 .

[0094] Finally, a metal block 4 electrically connected to the piezoresistive layer 231 is formed at the conductive contact hole 281. Preferably, the metal block 4 can be formed by depositing a high temperature resistant conductive metal Pad and patterning it.

[0095] S9. Obtain a pressure sensor.

[0096] It should be noted that, in an actual production process, the manufacturing method of the pressure sensor of the first embodiment above can be used to obtain an absolute pressure type pressure sensor.

[0097] Embodiment 2

[0098] like Fig.17The figure shows a schematic diagram of the structure of the pressure sensor provided in the second embodiment. The difference between the second embodiment and the first embodiment is that the second embodiment can obtain a gauge pressure or differential pressure type pressure sensor.

[0099] Specifically, in the second embodiment, in order to obtain a gauge pressure or differential pressure type pressure sensor, an air inlet 100 is formed on the pressure sensor, which passes through the substrate structure 1 and the sensitive membrane layer structure 3, and the air inlet 100 is connected to the inner cavity of the bonding slot 10 to meet the structural requirements of a gauge pressure or differential pressure type pressure sensor.

[0100] Furthermore, the manufacturing method of the pressure sensor provided in the second embodiment is different from that in the first embodiment in that after S8 and before S9 in the first embodiment, a step is added:

[0101] An air inlet 100 is formed on the pressure sensor, penetrating the substrate structure 1 and the sensitive film layer structure 3, and the air inlet 100 is connected to the inner cavity of the bonding slot 10 (eg, Fig.13 ).

[0102] Specifically, the process of forming the air inlet 100 is as follows:

[0103] First, silicon deep reactive ions are used to etch a first through hole on the middle silicon material layer 11, and the etching is stopped at the bottom surface of the insulating layer 12 on the substrate using the self-stopping principle to ensure etching consistency and prevent the island structure from being damaged due to over-etching.

[0104] Then, the insulating layer 12 on the substrate, the pressure sensitive film 31 and the position on the sensitive film insulating layer 32 corresponding to the first through hole are removed to form a second through hole. The first through hole is connected to the second through hole to obtain the air inlet 100 .

[0105] Embodiment 3

[0106] like Fig.18 The diagram is a schematic diagram of the structure of the pressure sensor provided in the third embodiment. The third embodiment can be applied to gauge pressure or differential pressure type pressure sensors. The third embodiment is different from the second embodiment mentioned above in that the pressure sensor provided in the third embodiment does not have a thick semiconductor material layer and a top second lower insulating layer covering the thick semiconductor material layer.

[0107] Specifically, the top structure 2 of the pressure sensor includes a first silicon layer 21 , a first insulating layer 22 disposed on the back of the first silicon layer 21 , a piezoresistive layer 231 disposed on the back of the first insulating layer 22 , and a top first lower insulating layer 24 disposed on the front of the first silicon layer 21 .

[0108] It can be understood that in the third embodiment, the sensitive film layer structure 3 covering the lower surface of the top structure 2 specifically means that the sensitive film layer structure 3 covers the lower surface of the top first lower insulating layer 24 corresponding to the bonding groove 10 .

[0109] The pressure sensor of the third embodiment adopts the first silicon layer 21 as the "beam" layer in the beam-membrane stress concentration structure, and utilizes the sensitive film layer structure 3 formed on the inner wall of the hole wall insulating layer 27 and extending downward to cover the inner wall of the bonding groove 10 and the lower surface of the top structure 2 to make the "membrane" layer in the beam-membrane stress concentration structure. The pressure sensor can process a thin pressure-sensitive film to measure tiny pressures, and at the same time make good use of the characteristics of the wafer, so that the piezoresistive structure (piezoresistive layer) has no PN junction and can work at high temperatures (greater than 150°C).

[0110] Furthermore, the method for manufacturing the pressure sensor provided in the third embodiment is different from that in the second embodiment in that the process of forming the thick semiconductor material layer 25 and the top second lower insulating layer 26 in step S1 is eliminated.

[0111] Specifically, step S1 in the third embodiment is only:

[0112] Select as Figure 2 The first silicon wafer a is shown, and a top first lower insulating layer 24 is grown on the front side of the first silicon wafer a to obtain a top initial structure.

[0113] 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.

[0114] 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, a top structure and a sensitive film layer 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 and a top first lower insulating layer arranged on the front of the first silicon layer; a deposition hole and a beam hole penetrating the top first lower insulating layer, the first silicon layer and the first insulating layer are formed on the top structure, and a hole wall insulating layer is formed on the hole wall of the deposition hole; The upper surface of the substrate structure is recessed downward to form a bonding groove, the top structure is inverted on the substrate structure, the front side of the top first lower insulating layer faces the substrate structure, and the deposition hole is connected to the bonding groove; The sensitive film layer structure is formed on the inner wall of the hole wall insulating layer and extends downward to cover the inner wall of the bonding groove and the lower surface of the top structure.

2. The pressure sensor according to claim 1, characterized in that: The sensitive film layer structure includes a pressure sensitive film and a sensitive film insulating layer. The pressure sensitive film is formed on the inner wall of the hole wall insulating layer and extends downward to cover the inner wall of the bonding groove and the lower surface of the top structure. The sensitive film insulating layer is formed on the pressure sensitive film and covers the pressure sensitive film.

3. The pressure sensor according to claim 2, characterized in that: The top structure also includes a thick semiconductor material layer formed on the front side of the top first lower insulating layer and a top second lower insulating layer covering the thick semiconductor material layer, wherein the thick semiconductor material layer is used as an island structure; the thick semiconductor material layer is bonded in the bonding groove and forms a gap with the bonding groove.

4. The pressure sensor according to claim 1, characterized in that: The top structure further comprises an insulating protection layer deposited on the upper surface of the first insulating layer and covering the piezoresistive layer, wherein at least one conductive contact hole corresponding to the piezoresistive layer is formed on the insulating protection layer; The pressure sensor further includes a metal block correspondingly arranged at the conductive contact hole and electrically connected to the piezoresistive layer, and each conductive contact hole is correspondingly provided with at least one metal block.

5. The pressure sensor according to claim 1, characterized in that: An air inlet penetrating through the substrate structure and the sensitive film layer structure is formed on the pressure sensor, and the air inlet is communicated with the inner cavity 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 top layer and a first lower insulating layer on the front side of the first silicon wafer to obtain a top layer initial structure; the first silicon wafer is a wafer having a silicon structure on a double insulating layer (Double-SOI, DSOI), and 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 which are sequentially stacked and covered, and a surface of the first silicon layer facing away from the third silicon layer is a front side of the first silicon layer; S2, forming a substrate structure, wherein a bonding groove and an insulating layer on the substrate are formed on the substrate structure; S3, invertingly bonding the top primary structure to the substrate structure, so that the front side of the top first lower insulating layer faces the substrate structure; S4, removing redundant layer structures, including: removing the back insulating layer, the third silicon layer and the second insulating layer of the top primary structure; S5, patterning the top first lower insulating layer, the first silicon layer, the first insulating layer and the second silicon layer to form a deposition hole penetrating the top first lower insulating layer, the first silicon layer, the first insulating layer and the second silicon layer, and depositing a hole wall insulating layer on the hole wall of the deposition hole; S6, depositing to form a sensitive film layer structure, wherein the sensitive film layer structure extends downward from the inner wall of the hole wall insulating layer and covers the inner wall of the bonding groove and the lower surface of the top structure; S7, doping the second silicon layer, and patterning the doped second silicon layer to form a piezoresistive layer; S8, etching the top layer, the first lower insulating layer, the first silicon layer and the first insulating layer to form a beam hole; S9. Obtain a pressure sensor.

7. The method for manufacturing a pressure sensor according to claim 6, characterized in that: In S6, the deposition to form a sensitive film layer structure includes: Depositing a sensitive film material, so that the sensitive film material is deposited on the inner wall of the hole wall insulating layer, the inner wall of the bonding groove, the lower surface of the top structure and the upper surface of the top structure; growing an insulating material covering the pressure sensitive film on the pressure sensitive film; The sensitive film material and the insulating material on the second silicon layer are removed to obtain a pressure sensitive film composed of the remaining sensitive film material and a sensitive film insulating layer composed of the remaining insulating material, thereby obtaining the sensitive film layer structure.

8. The method for manufacturing a pressure sensor according to claim 6, wherein: The S1 further includes: forming a thick semiconductor material layer serving as an island structure on the front side of the first silicon wafer; A top second lower insulating layer covering the thick semiconductor material layer is generated on the front side of the first silicon wafer.

9. The method for manufacturing a pressure sensor according to claim 6, characterized in that: After S8 and before S9, it also includes: Depositing an insulating protective layer covering the piezoresistive layer on the upper surface of the first insulating layer; Patterning the insulating protection layer to form a conductive contact hole corresponding to the piezoresistive layer; A metal block electrically conducting the piezoresistive layer is formed at the conductive contact hole.

10. The method for manufacturing a pressure sensor according to claim 6, characterized in that: After S8 and before S9, it also includes: An air inlet penetrating the substrate structure and the sensitive film layer structure is formed on the pressure sensor, and the air inlet is communicated with the inner cavity of the bonding groove.

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