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. In the top structure, a first silicon layer is used as a pressure sensitive film; a second silicon layer is used as a piezoresistive layer; a thick semiconductor material layer used as an island structure is formed on the front of the first silicon layer; a top lower insulating layer covering the first silicon layer and the thick semiconductor material layer is also formed on the front of the first silicon layer; the upper surface of the substrate structure is recessed downward to form a bonding groove, the thick semiconductor material layer is bonded in the bonding groove and forms a gap with the bonding groove; a first electrical connection channel used for self-detection is formed between the first silicon layer and the substrate structure; a second electrical connection channel used as a piezoresistive structure is formed between the second silicon layer and the substrate structure; the first electrical connection channel is insulated from the second electrical connection channel, and the second electrical connection channel is insulated from the first silicon layer. The pressure sensor forms a capacitive structure between the island structure and the substrate structure to achieve the purpose of online self-calibration of the pressure sensor.

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] At present, MEMS pressure sensors mostly use PN junctions to achieve electrical isolation between force-sensitive piezoresistive elements. Under normal temperature conditions, PN junctions can effectively prevent the generation of leakage current, but under high temperature conditions (generally greater than 150 degrees Celsius), the leakage current of the PN junction increases significantly, affecting the stability of the sensor output and even causing the sensor to fail. Therefore, MEMS pressure sensors using PN junctions can only work in environments below 150°C.

[0004] In addition, existing MEMS pressure sensors mostly use the back-side pressure sensing mode of the pressure-sensitive membrane, which increases the nonlinearity of the pressure-sensitive membrane. However, when the measured pressure is too large, the sealing material of the front-mounted chip will leak or even be pushed away by the high pressure. This limits the pressure range that the MEMS pressure sensor can measure, and the existing technology cannot avoid the nonlinear increase effect of pressure measurement.

[0005] In addition, existing piezoresistive pressure sensors are generally detected through additional detection devices and cannot perform online self-detection. Summary of the invention

[0006] Based on this, the present invention provides a pressure sensor and a method for manufacturing the same. A capacitor structure is formed between the island structure and the substrate structure to achieve the purpose of online self-calibration of the pressure sensor.

[0007] A pressure sensor, comprising a substrate structure and a top structure, wherein the top structure comprises a first silicon layer, a second silicon layer arranged on the back of the first silicon layer, and a first insulating layer arranged between the first silicon layer and the second silicon layer; the first silicon layer is used as a pressure sensitive film; the second silicon layer is used as a piezoresistive layer; a thick semiconductor material layer electrically connected to the first silicon layer is formed on the front side of the first silicon layer, and the thick semiconductor material layer is used as an island structure; a top lower insulating layer covering the first silicon layer and the thick semiconductor material layer is also formed on the front side of the first silicon layer;

[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 pressure sensor is formed with a first electrical connection hole and a second electrical connection hole; the first electrical connection hole is filled with a conductive semiconductor material so that a first electrical connection channel for self-detection is formed between the first silicon layer and the substrate structure; the second electrical connection hole is filled with a conductive semiconductor material so that a second electrical connection channel for a piezoresistive structure is formed between the second silicon layer and the substrate structure;

[0010] The first electrical connection channel is insulated from the second electrical connection channel, and the second electrical connection channel is insulated from the first silicon layer.

[0011] In the above-mentioned pressure sensor, a thick semiconductor material layer used as an island structure is formed on the front side of the first silicon layer and is connected to 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. A first electrical connection channel is formed between the first silicon layer and the substrate structure, so that a capacitor structure is formed between the island structure and the substrate structure. When a voltage value is applied between the capacitors, the electrostatic force can pull the island structure toward the substrate structure, thereby causing the pressure sensitive film (i.e., the first silicon layer) to deform. This effect is used to perform online self-calibration of the pressure sensor. In addition, the thick semiconductor material layer used as the island structure is formed on the front side of the first silicon layer. The front pressure sensing technology of the pressure sensitive film (i.e., the first silicon layer) can be used to avoid the occurrence of leakage of the sealing material or the phenomenon of being pushed away by high pressure. At the same time, the nonlinearity of the pressure sensitive film can be reduced, and the range of measurable pressure can be increased.

[0012] In one of the embodiments, the substrate structure includes a middle silicon material layer and an insulating layer on the substrate formed on the upper surface of the middle silicon material layer, and the lower surface of the middle silicon material layer is doped to form a doped layer.

[0013] In one embodiment, a first substrate region, a second substrate region and a third substrate region which are insulated from each other are formed on the substrate structure, the first silicon layer is connected to the first substrate region through the first electrical connection hole, the second silicon layer is connected to the second substrate region through the second electrical connection hole, and the bonding groove is formed in the third substrate region;

[0014] The pressure sensor further includes a first insulating protective layer deposited on the upper surface of the top structure and a second insulating protective layer deposited on the lower surface of the substrate structure;

[0015] A first conductive contact hole corresponding to the first substrate region, a second conductive contact hole corresponding to the second substrate region, and a third conductive contact hole corresponding to the third substrate region are formed on the second insulating protection layer.

[0016] In one embodiment, at least one is provided in the first substrate region, at least one is provided in the second substrate region, and at least one is provided in the third substrate region;

[0017] There is at least one first conductive contact hole, there is at least one second conductive contact hole, and there is at least one third conductive contact hole.

[0018] The present invention also provides a method for manufacturing a pressure sensor, which comprises the steps of:

[0019] 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, and pattern the front insulating layer to form a notch; the first silicon wafer is a wafer with a double-layer "silicon on insulating layer" structure (Double-SOI, 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;

[0020] S2, forming a thick semiconductor material layer serving as an island structure at the notch;

[0021] S3, removing the front insulating layer grown in S1, and regenerating a top lower insulating layer covering the first silicon layer and the thick semiconductor material layer on the front side of the first silicon wafer to obtain a top initial structure;

[0022] S4, forming a substrate structure, wherein a bonding groove is formed on the substrate structure;

[0023] 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;

[0024] S6, removing redundant layer structures, including: removing the back insulating layer, the third silicon layer and the second insulating layer of the top initial structure to obtain a top structure;

[0025] S7, forming a first electrical connection hole penetrating the substrate structure and the insulating layer under the top layer and a second electrical connection hole penetrating the top layer structure on the pressure sensor;

[0026] S8. Forming a first electrical connection channel and a second electrical connection channel that are insulated from each other: after forming the first electrical connection hole, filling the first electrical connection hole with a conductive semiconductor material to form a first electrical connection channel between the first silicon layer and the substrate structure; after forming the second electrical connection hole, filling the second electrical connection hole with a conductive semiconductor material to form a second electrical connection channel between the second silicon layer and the substrate structure; the second electrical connection channel is insulated from the first silicon layer.

[0027] In one embodiment, in S4, forming a substrate structure includes:

[0028] Selecting a second silicon wafer and using the second silicon wafer as the middle silicon material layer, and forming a substrate insulating layer on the upper surface and the lower surface of the second silicon wafer respectively;

[0029] Patterning the second silicon wafer and the substrate insulating layer formed on the upper surface of the second silicon wafer to form the bonding groove;

[0030] Removing the substrate insulating layer on the upper surface of the second silicon wafer, and regenerating a substrate insulating layer on the upper surface of the second silicon wafer to obtain the substrate structure;

[0031] In the step S6, the step of removing the redundant layer structure further comprises: removing a substrate insulating layer formed on the lower surface of the second silicon wafer.

[0032] In one embodiment, after S6 and before S7, the steps include:

[0033] doping the second silicon layer to form a piezoresistive layer, and growing a top insulating layer on the upper surface of the piezoresistive layer;

[0034] The lower surface of the second silicon wafer is doped to form a doped layer, and a sub-substrate insulating layer is grown on the lower surface of the doped layer.

[0035] In one embodiment, in S7, while forming the second electrical connection hole, the substrate structure is etched to form at least one first electrical isolation trench and at least one second electrical isolation trench penetrating the middle silicon material layer, and inner walls of the first electrical isolation trench and the second electrical isolation trench are respectively grown with trench insulation layers;

[0036] The first electrical isolation trench surrounds a first substrate region on the middle silicon material layer that is conductive with the first silicon layer, the second electrical isolation trench surrounds a second substrate region on the middle silicon material layer that is conductive with the second silicon layer, and the region on the middle silicon material layer excluding the first substrate region and the second substrate region forms a third substrate region.

[0037] In one embodiment, after S8, the method further includes:

[0038] S9, removing a portion of the top insulating layer and the bottom insulating layer of the substrate, and patterning the second silicon layer to form a piezoresistive structure;

[0039] S10, depositing a first insulating protective layer on the upper surface of the top structure, and depositing a second insulating protective layer on the lower surface of the substrate structure;

[0040] S11, patterning the second insulating protection layer to form a first conductive contact hole corresponding to the first substrate region, a second conductive contact hole corresponding to the second substrate region, and a third conductive contact hole corresponding to the third substrate region;

[0041] S12. Form a first metal block electrically connected to the first substrate region at the first conductive contact hole, form a second metal block electrically connected to the second substrate region at the second conductive contact hole, and form a third metal block electrically connected to the third substrate region at the third conductive contact hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic longitudinal cross-sectional view of a pressure sensor according to an embodiment of the present invention;

[0043] Figures 2 to 15 for Figure 1 The process flow diagram of the pressure sensor is shown. DETAILED DESCRIPTION

[0044] 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.

[0045] 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.

[0046] 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.

[0047] like Figure 1As 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 and a top structure 2, wherein the top structure 2 includes a first silicon layer 21, a second silicon layer 22 arranged on the back of the first silicon layer 21, and a first insulating layer 23 arranged between the first silicon layer 21 and the second silicon layer 22. The first silicon layer 231 is used as a pressure sensitive film. The second silicon layer 22 is used as a piezoresistive layer. A thick semiconductor material layer 24 electrically connected to the first silicon layer 21 is formed on the front side of the first silicon layer 21, and the thick semiconductor material layer is used as an island structure; a top lower insulating layer 25 covering the first silicon layer 21 and the thick semiconductor material layer 24 is also formed on the front side of the first silicon layer 21.

[0048] The upper surface of the substrate structure 1 is recessed downward to form a bonding groove 10 , and the thick semiconductor material layer 24 is bonded in the bonding groove 10 and forms a gap with the bonding groove 10 .

[0049] The pressure sensor is formed with a first electrical connection hole 3 and a second electrical connection hole 4; the first electrical connection hole 3 is filled with a conductive semiconductor material so that a first electrical connection channel (such as a first electrical connection channel 4) for self-detection is formed between the first silicon layer 21 and the substrate structure 1. Figure 1 The second electrical connection hole 4 is filled with a conductive semiconductor material to form a second electrical connection channel (such as a piezoresistive structure) between the second silicon layer 22 and the substrate structure 1. Fig.14 (shown by the dashed line).

[0050] The first electrical connection channel is insulated from the second electrical connection channel, and the second electrical connection channel is insulated from the first silicon layer 21 .

[0051] In the pressure sensor 1, a thick semiconductor material layer 24 used as an island structure is formed on the front of the first silicon layer 21, and the thick semiconductor material layer 24 is bonded to the bonding groove 10 of the substrate structure 1 and forms a gap with the bonding groove 10, and a first electrical connection channel is formed between the first silicon layer 21 and the substrate structure 1, so that a capacitor structure is formed between the island structure and the substrate structure 1. When a voltage value is applied between the capacitors, the electrostatic force can pull the island structure toward the substrate structure 1, thereby causing the pressure sensitive film (i.e., the first silicon layer 21) to deform. By using this effect, the online self-calibration of the pressure sensor is performed. In addition, the thick semiconductor material layer 24 used as the island structure is formed on the front of the first silicon layer 21. By using the front pressure sensing technology of the pressure sensitive film (i.e., the first silicon layer 21), the sealing material can be prevented from leaking or being pushed away by high pressure, and the nonlinearity of the pressure sensitive film can be reduced, thereby increasing the range of measurable pressure. 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 the 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-side opening method in the prior art, the lateral size of the pressure sensitive film is easier to control.

[0052] In one embodiment, Figure 1 As shown, the doping type of the first silicon layer 21 and the second silicon layer 22 is consistent, 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 and the second silicon layer 22 are both P-type doped.

[0053] In a preferred embodiment, the second silicon layer 22 may be doped by implanting boron ions, and the doping concentration of the second silicon layer 22 is greater than 1E20 cm -3 .

[0054] In one embodiment, Figure 1 As shown, the first insulating layer 23 is a silicon oxide layer.

[0055] In one embodiment, Figure 1 As shown, the thick semiconductor material layer 24 is in-situ doped, and the doping type of the thick semiconductor material layer 24 is consistent with the doping type of the first silicon layer 21 so that the thick semiconductor material layer 24 and the first silicon layer 21 are electrically connected.

[0056] In one embodiment, Figure 1As shown, the conductive semiconductor material is an in-situ doped polysilicon material to achieve electrical conduction between the first silicon layer 21 and the substrate structure 1 , and to achieve electrical conduction between the second silicon layer 22 and the substrate structure 1 .

[0057] In one embodiment, Figure 1 As shown, the substrate structure 1 includes a middle silicon material layer 11 and a substrate insulating layer 12 formed on the upper surface of the middle silicon material layer 11, and the lower surface of the middle silicon material layer 11 is doped to form a doping layer 13. Preferably, the doping layer 13 is doped by injecting boron ions, and the doping concentration of the doping layer 13 is greater than 1E20cm -3 .

[0058] In one embodiment, Figure 1 As shown, a mutually insulated first substrate region 111, a second substrate region 112 and a third substrate region 113 are formed on the middle silicon material layer 11, the first silicon layer 21 is connected to the first substrate region 111 through the first electrical connection hole 3, the second silicon layer 22 is connected to the second substrate region 112 through the second electrical connection hole 4, and the bonding groove 10 is formed in the third substrate region 113. It should be noted that the "first", "second" and "third" of the first substrate region 111, the second substrate region 112 and the third substrate region 113 are only functional limitations of the structure and do not represent the number of each region. Specifically, at least one of the first substrate region 111 is provided, at least one of the second substrate region 112 is provided, and at least one of the third substrate region 113 is provided.

[0059] Furthermore, in order to achieve mutual insulation between the first substrate region 111, the second substrate region 112 and the third substrate region 113, as shown in FIG. Figure 1 As shown, at least one first electrical isolation trench 14 and at least one second electrical isolation trench 15 penetrating the middle silicon material layer 11 are formed on the substrate structure 1, and trench insulating layers are grown on the inner walls of the first electrical isolation trench 14 and the second electrical isolation trench 15. It should be noted that the "first" and "second" of the first electrical isolation trench 14 and the second electrical isolation trench 15 are only functional limitations of the structure and do not represent the number of each electrical isolation trench.

[0060] The first electrical isolation groove 14 encloses a first substrate region 111 on the substrate structure 1 that is conductive with the first silicon layer 21, and the second electrical isolation groove 15 encloses a second substrate region 112 on the substrate structure 1 that is conductive with the second silicon layer 22. The area on the substrate structure 1 other than the first substrate region 111 and the second substrate region 112 forms a third substrate region 113, thereby achieving mutual insulation among the first substrate region 111, the second substrate region 112 and the third substrate region 113, and further achieving insulation between the first electrical connection channel and the second electrical connection channel.

[0061] In one embodiment, Figure 1 As shown, the pressure sensor further includes a first insulating protection layer 5 deposited on the upper surface of the top structure 1 and a second insulating protection layer 6 deposited on the lower surface of the substrate structure 1 .

[0062] The second insulating protection layer 6 is provided with a first conductive contact hole 61 corresponding to the first substrate region 111, a second conductive contact hole 62 corresponding to the second substrate region 112, and a third conductive contact hole 63 corresponding to the third substrate region 113. The first conductive contact hole 61, the second conductive contact hole 62, and the third conductive contact hole 63 are provided to energize the pressure sensor. It should be noted that the "first", "second", and "third" of the first conductive contact hole 61, the second conductive contact hole 62, and the third substrate region 113 are only structural functional limitations and do not represent the number of each conductive contact hole. Specifically, at least one first conductive contact hole 61 is provided, at least one second conductive contact hole 62 is provided, and at least one third conductive contact hole 63 is provided.

[0063] Furthermore, each of the first substrate regions 111 may be provided with one or more of the first conductive contact holes 61, each of the second substrate regions 112 may be provided with one or more of the second conductive contact holes 62, and each of the third substrate regions 113 may be provided with one or more of the third conductive contact holes 63.

[0064] In one embodiment, Figure 1 As shown, the pressure sensor also includes a first metal block 7 arranged at the first conductive contact hole 61 and electrically connected to the first substrate area 111, a second metal block 8 arranged at the second conductive contact hole 62 and electrically connected to the second substrate area 112, and a third metal block 9 arranged at the third conductive contact hole 63 and electrically connected to the third substrate area 113, so as to facilitate the power supply of the pressure sensor.

[0065] like Figures 2 to 14As shown, it is a method for manufacturing a pressure sensor according to an embodiment of the present invention, which comprises the steps of:

[0066] S1, select Figure 2 The first silicon wafer a shown in FIG. 1 is provided, 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, and the front insulating layer 201 is patterned to form a notch 2011 (such as 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 23, a second silicon layer 22, a second insulating layer 26 and a third silicon layer 27 stacked in sequence, and the surface of the first silicon layer 21 facing away from the third silicon layer 27 is the front side of the first silicon layer 21, that is, the front side of the first silicon wafer a.

[0067] Preferably, the first silicon layer 21, the second silicon layer 22 and the third silicon layer 27 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 22 and the third silicon layer 27 can be freely selected according to actual needs. In this embodiment, the first silicon layer 21, the second silicon layer 22 and the third silicon layer 27 all adopt (100) crystal orientation and P-type doping.

[0068] Furthermore, the first insulating layer 23 and the second insulating layer 26 are both silicon oxide layers.

[0069] S2, forming a thick semiconductor material layer 24 (such as Figure 4 ).

[0070] Specifically, in step S2, the thick semiconductor material layer 24 is formed by:

[0071] First, thick semiconductor materials, such as epitaxially grown polysilicon materials, are grown on the front and back sides of the first silicon wafer a, respectively. The thick semiconductor material is doped in situ so that its doping type is consistent with the doping type of the first silicon layer 21 (for example, in this embodiment, both are P-type doping). In this way, the thick semiconductor material on the front side of the first silicon wafer a can be electrically connected to the first silicon layer 21. The thickness of the thick semiconductor material can be processed according to the design requirements of the pressure sensor.

[0072] 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 24 serving as an island structure.

[0073] S3, removing the front insulating layer 201 grown in S1, and regenerating a top lower insulating layer 25 (such as Figure 5 ), and obtain the top layer initial structure. Preferably, the top layer lower insulating layer 25 is formed by using silicon oxide material.

[0074] S4, forming a substrate structure 1, wherein a bonding groove 10 is formed on the substrate structure 1.

[0075] Specifically, in step S4, the substrate structure 1 is formed by:

[0076] 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 .

[0077] 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 ).

[0078] 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.

[0079] S5, such as Figure 8 As shown, the top preliminary structure is inverted, and the thick semiconductor material layer 24 is bonded in the bonding groove 10 , and a gap is formed between the thick semiconductor material layer 24 and the bonding groove 10 .

[0080] S6. Remove unnecessary layers of structure.

[0081] Specifically, in step S6, removing the redundant layer structure includes:

[0082] The back insulating layer 202, the third silicon layer 27 and the second insulating layer 26 of the top structure are removed to obtain a top structure 2; the substrate insulating layer 101 formed on the lower surface of the second silicon wafer b is removed (eg Fig. 9 ).

[0083] After completing step S6 of removing the redundant layer structure, the following steps may be performed:

[0084] like Fig.10 As shown, the second silicon layer 22 is doped to form a piezoresistive layer, and a top insulating layer 203 is grown on the upper surface of the piezoresistive layer. The doping elements, concentration and doping process of the second silicon layer 22 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 .

[0085] The lower surface of the second silicon wafer b is doped to form a doping layer 13 , and a lower substrate insulating layer 102 is grown on the lower surface of the doping layer 13 .

[0086] S7, such as Figures 11 to 13 As shown, a first electrical connection hole 3 and a second electrical connection hole 4 are formed on the pressure sensor.

[0087] Specifically, in S7, the first electrical connection hole 3 (such as Fig.11 ) is as follows:

[0088] The first electrical connection hole 3 penetrating the substrate structure 1 and the top lower insulating layer 25 is formed on the pressure sensor by using the through silicon via technology.

[0089] The electrical signal from the front of the pressure sensor is introduced to the back of the pressure sensor by using the through silicon via technology, so that the front of the pressure sensor can be surface mounted. At the same time, the front pressure sensing technology of the pressure sensitive film (i.e., the first silicon layer 21) can be used, which reduces the nonlinearity of the pressure sensor and increases the range of pressure that the pressure sensor can measure.

[0090] In the step S7, the second electrical connection hole 4 (such as Fig.12 and Fig.13 ) is as follows:

[0091] First, an electrical connection through hole 204 penetrating the top structure 2 is formed on the pressure sensor by using silicon deep reactive ion etching technology.

[0092] Then, a connection hole insulating layer (such as silicon oxide) is grown on the inner wall of the electrical connection hole 204, and the connection hole insulating layer surrounds a filling hole 205 (such as Fig.12 ).

[0093] Afterwards, the position on the insulating layer 12 on the substrate corresponding to the filling hole 205 is etched to form the second electrical connection hole 4 (such as Fig.13 ).

[0094] In one embodiment, if Fig.12 and Fig.13 As shown, while completing the formation of the second electrical connection hole in S7, the substrate structure 1 is etched to form a first electrical isolation trench 14 and a second electrical isolation trench 15 that penetrate the middle silicon material layer 11, and trench insulation layers are grown on the inner walls of the first electrical isolation trench 14 and the second electrical isolation trench 15 respectively.

[0095] The first electrical isolation groove 14 encloses a first substrate region 111 on the middle silicon material layer 11 that is conductive to the first silicon layer 21, and the second electrical isolation groove 15 encloses a second substrate region 112 on the middle silicon material layer 11 that is conductive to the second silicon layer 22. The area on the middle silicon material layer 11 other than the first substrate region 111 and the second substrate region 112 forms a third substrate region 113.

[0096] S8, forming a mutually insulated first electrical connection channel and a second electrical connection channel: after forming the first electrical connection hole 3, filling the first electrical connection hole 3 with a conductive semiconductor material so that a first electrical connection channel (such as Figure 1 ); After forming the second electrical connection hole 4, a conductive semiconductor material is filled into the second electrical connection hole 4 to form a second electrical connection channel (such as Fig.14 ); the second electrical connection channel is insulated from the first silicon layer 21. The first electrical connection channel is used for self-detection of the pressure sensor, and the second electrical connection channel is used as a piezoresistive structure.

[0097] Preferably, the conductive semiconductor material filled into the first electrical connection hole 3 and the second electrical connection hole 4 is an in-situ doped polysilicon material.

[0098] Furthermore, the top insulating layer 203 may be patterned so that a through hole 2031 (eg, Fig.13 ), and then fill the through hole 2031 and the second electrical connection hole 4 with a conductive semiconductor material to form a second electrical connection channel (such as Fig.14 ).

[0099] In one embodiment, the alignment accuracy of the relative positions of the piezoresistive structure and the island structure is determined only by the bonding accuracy, which can effectively eliminate the influence of lateral etching in the back etching process.

[0100] S9, removing part of the top insulating layer 203 and the bottom insulating layer 102 of the substrate, and patterning the second silicon layer 22 to form a piezoresistive structure (such as Fig.15 ).

[0101] S10, depositing a first insulating protective layer 5 on the upper surface of the top structure 2, and depositing a second insulating protective layer 6 on the lower surface of the substrate structure 1. Preferably, the second insulating protective layer 6 can be formed by depositing silicon nitride material.

[0102] S11 , patterning the second insulating protection layer 6 to form a first conductive contact hole 61 corresponding to the first substrate region 111 , a second conductive contact hole 62 corresponding to the second substrate region 112 , and a third conductive contact hole 63 corresponding to the third substrate region 113 .

[0103] S12, forming a first metal block 7 electrically connected to the first substrate region 111 at the first conductive contact hole 61, forming a second metal block 8 electrically connected to the second substrate region 112 at the second conductive contact hole 62, and forming a third metal block 9 electrically connected to the third substrate region 113 at the third conductive contact hole 63. Preferably, the first metal block 7, the second metal block 8 and the third metal block 9 can be formed by depositing a high temperature resistant conductive metal Pad and patterning it.

[0104] 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.

[0105] 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 second silicon layer arranged on the back of the first silicon layer, and a first insulating layer arranged between the first silicon layer and the second silicon layer; The first silicon layer is used as a pressure sensitive membrane; The second silicon layer is used as a piezoresistive layer; A thick semiconductor material layer electrically connected to the first silicon layer is formed on the front side of the first silicon layer, and the thick semiconductor material layer is used as an island structure; a top lower insulating layer covering the first silicon layer and the thick semiconductor material layer is also formed on the front side of the first silicon 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; The pressure sensor is formed with a first electrical connection hole and a second electrical connection hole; the first electrical connection hole is filled with a conductive semiconductor material so as to form a first electrical connection channel for self-detection between the first silicon layer and the substrate structure; The second electrical connection hole is filled with a conductive semiconductor material so as to form a second electrical connection channel serving as a piezoresistive structure between the second silicon layer and the substrate structure; The first electrical connection channel is insulated from the second electrical connection channel, and the second electrical connection channel is insulated from the first silicon layer; The substrate structure comprises a middle silicon material layer and an insulating layer on the substrate formed on the upper surface of the middle silicon material layer, and the lower surface of the middle silicon material layer is doped to form a doping layer; The substrate structure comprises a first substrate region, a second substrate region and a third substrate region which are insulated from each other, the first silicon layer is connected to the first substrate region through the first electrical connection hole, the second silicon layer is connected to the second substrate region through the second electrical connection hole, and the bonding groove is formed in the third substrate region; The pressure sensor further includes a first insulating protective layer deposited on the upper surface of the top structure and a second insulating protective layer deposited on the lower surface of the substrate structure; A first conductive contact hole corresponding to the first substrate region, a second conductive contact hole corresponding to the second substrate region, and a third conductive contact hole corresponding to the third substrate region are formed on the second insulating protection layer.

2. The pressure sensor according to claim 1, characterized in that: The first substrate region is provided with at least one, the second substrate region is provided with at least one, and the third substrate region is provided with at least one; There is at least one first conductive contact hole, there is at least one second conductive contact hole, and there is at least one third conductive contact hole.

3. A method for manufacturing a pressure sensor according to claim 1, 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, and pattern the front insulating layer to form a notch; the first silicon wafer is a wafer with a double-layer "silicon on insulating layer" structure, 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 the front of the first silicon layer; S2, forming a thick semiconductor material layer serving as an island structure at the notch; S3, removing the front insulating layer grown in S1, and regenerating a top lower insulating layer covering the first silicon layer and the thick semiconductor material layer on the front side 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 initial structure to obtain a top structure; S7, forming a first electrical connection hole penetrating the substrate structure and the insulating layer under the top layer and a second electrical connection hole penetrating the top layer structure on the pressure sensor; S8. Forming a first electrical connection channel and a second electrical connection channel that are insulated from each other: after forming the first electrical connection hole, filling the first electrical connection hole with a conductive semiconductor material to form a first electrical connection channel between the first silicon layer and the substrate structure; after forming the second electrical connection hole, filling the second electrical connection hole with a conductive semiconductor material to form a second electrical connection channel between the second silicon layer and the substrate structure; the second electrical connection channel is insulated from the first silicon layer.

4. The method for manufacturing a pressure sensor according to claim 3, characterized in that: In the step S4, forming a substrate structure includes: Selecting a second silicon wafer and using the second silicon wafer as the middle silicon material layer, and forming a substrate insulating layer on the upper surface and the lower surface of the second silicon wafer respectively; Patterning the second silicon wafer and the substrate insulating layer formed on the upper surface of the second silicon wafer to form the bonding groove; Removing the substrate insulating layer on the upper surface of the second silicon wafer, and regenerating the substrate upper insulating layer on the upper surface of the second silicon wafer to obtain the substrate structure; In the step S6, the step of removing the redundant layer structure further comprises: removing a substrate insulating layer formed on the lower surface of the second silicon wafer.

5. The method for manufacturing a pressure sensor according to claim 4, characterized in that: After S6 and before S7, including: doping the second silicon layer to form a piezoresistive layer, and growing a top insulating layer on the upper surface of the piezoresistive layer; The lower surface of the second silicon wafer is doped to form a doped layer, and a sub-substrate insulating layer is grown on the lower surface of the doped layer.

6. The method for manufacturing a pressure sensor according to claim 5, characterized in that: In S7, while forming the second electrical connection hole, the substrate structure is etched to form at least one first electrical isolation trench and at least one second electrical isolation trench penetrating the middle silicon material layer, and inner walls of the first electrical isolation trench and the second electrical isolation trench are respectively grown with trench insulation layers; The first electrical isolation trench surrounds a first substrate region on the middle silicon material layer that is conductive with the first silicon layer, the second electrical isolation trench surrounds a second substrate region on the middle silicon material layer that is conductive with the second silicon layer, and the region on the middle silicon material layer excluding the first substrate region and the second substrate region forms a third substrate region.

7. The method for manufacturing a pressure sensor according to claim 6, characterized in that: After S8, the following steps are also included: S9, removing a portion of the top insulating layer and the bottom insulating layer of the substrate, and patterning the second silicon layer to form a piezoresistive structure; S10, depositing a first insulating protective layer on the upper surface of the top structure, and depositing a second insulating protective layer on the lower surface of the substrate structure; S11, patterning the second insulating protection layer to form a first conductive contact hole corresponding to the first substrate region, a second conductive contact hole corresponding to the second substrate region, and a third conductive contact hole corresponding to the third substrate region; S12. Form a first metal block electrically connected to the first substrate region at the first conductive contact hole, form a second metal block electrically connected to the second substrate region at the second conductive contact hole, and form a third metal block electrically connected to the third substrate region at the third conductive contact hole.

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