MEMS pressure sensor and pressure detection device

Abstract

The utility model discloses an MEMS pressure sensor and a pressure detection device. The MEMS pressure sensor includes a sensor sheet and a substrate. The sensor sheet comprises a pressure sensing structure, a detection circuit connected with the pressure sensing structure and a first interconnection point connected with the detection circuit; the substrate is provided with a signal processing circuit and a second interconnection point connected with the signal processing circuit. The sensor sheet and the substrate are oppositely arranged, and the first interconnection point and the second interconnection point are electrically connected in the direction perpendicular to the sensor sheet. The first interconnection point and the second interconnection point are electrically connected in the direction perpendicular to the sensor sheet, so that an original signal transmission channel between the detection circuit and the signal processing circuit is short, interference of external environment noise in the original signal transmission process is small, the anti-interference performance is improved, signals are not prone to attenuation, and the device performance is improved.

Description

Technical Field

[0001] The present application relates to the technical field of integrated circuits, and in particular to a MEMS pressure sensor and a pressure detection device. Background Art

[0002] MEMS pressure sensor is a micro device with pressure detection capability made by MEMS process, which is mainly divided into three categories: piezoresistive, capacitive and resonant, and is used in consumer electronics, industrial production and other fields. Among them, piezoresistive MEMS pressure sensor has the advantages of small size, light weight, simple structure, low cost and high measurement accuracy, so it has been widely used.

[0003] The working principle of the piezoresistive MEMS pressure sensor is to prepare a piezoresistor on a strain film (also called a pressure sensitive film). The strain film deforms under the action of external pressure and generates stress. The resistance of the piezoresistor changes due to the stress. Finally, the resistance change is converted into a voltage output through a detection circuit, and the voltage output value reflects the size of the external pressure.

[0004] In actual use, it is found that the original signal of the above-mentioned MEMS pressure sensor (not limited to the piezoresistive MEMS pressure sensor) is easily disturbed by the external environment during the transmission process. Utility Model Content

[0005] The purpose of this application is to disclose a MEMS pressure sensor and a pressure detection device.

[0006] The present application discloses a MEMS pressure sensor. The MEMS pressure sensor comprises a sensor sheet and a substrate. The sensor sheet comprises a pressure sensing structure, a detection circuit connected to the pressure sensing structure, and a first interconnection point connected to the detection circuit; the substrate is provided with a signal processing circuit and a second interconnection point connected to the signal processing circuit; the sensor sheet and the substrate are arranged opposite to each other, and the first interconnection point and the second interconnection point are electrically connected in a direction perpendicular to the sensor sheet.

[0007] In some embodiments, the sum of the height of the first interconnection point and the height of the second interconnection point is h, and h≤40 um.

[0008] In some embodiments, the sensor sheet includes a SOI buried oxide layer; the detection circuit and the first interconnection point are formed on the surface of the SOI buried oxide layer; the substrate includes a ROIC sheet, an insulating layer is arranged on the surface of the ROIC sheet, and the second interconnection point is arranged on the insulating layer; the SOI buried oxide layer covers the insulating layer on the ROIC sheet.

[0009] In some embodiments, the detection circuit is a Wheatstone bridge, and the first interconnection point is correspondingly arranged at the intersection of each two adjacent bridge arms.

[0010] In some embodiments, the sensor sheet is arranged opposite to the substrate to form a closed cavity, the detection circuit includes a first wiring connected to the first interconnection point; the signal processing circuit includes a second wiring connected to the second interconnection point, and the first interconnection point, the first wiring, the second interconnection point and the second wiring are all located in the cavity;

[0011] Alternatively, the sensor sheet and the substrate are arranged relative to each other to form a cavity with a through hole, the cavity is connected to the outside through the through hole, the detection circuit includes a first routing line connected to the first interconnection point; the signal processing circuit includes a second routing line connected to the second interconnection point, and the first interconnection point, the first routing line, the second interconnection point and the second routing line are all located in the cavity.

[0012] In some embodiments, the substrate includes a ROIC sheet, and the interior of the ROIC sheet includes the signal processing circuit; the signal processing circuit at least amplifies the original signal generated by the pressure sensing structure.

[0013] In some embodiments, the sensor sheet includes a first solder in a ring shape, and the first interconnection point is located within the area surrounded by the first solder; the substrate includes a second solder in a ring shape, and the second interconnection point is located within the area surrounded by the second solder, and the position of the second solder corresponds to the position of the first solder; the sensor sheet and the substrate are bonded through the first solder and the second solder.

[0014] In some embodiments, a height difference between the first interconnection point and the first solder is ±3 um; and / or a height difference between the second interconnection point and the second solder is ±3 um.

[0015] In some embodiments, the sensor sheet includes an SOI substrate layer and an SOI buried oxide layer on which the detection circuit is disposed; the SOI substrate layer is etched to form a cavity to form a pressure sensitive membrane of the pressure sensing structure; the cavity penetrates the SOI substrate layer to the buried oxide layer, or the depth of the cavity is less than the thickness of the SOI substrate layer.

[0016] In some embodiments, a projection of the cavity on a plane parallel to the SOI substrate layer is a square or a circle.

[0017] In some embodiments, the first interconnection point is located outside the membrane edge of the pressure sensitive membrane, and the distance from the corresponding membrane edge of the pressure sensitive membrane is 10 um to 50 um.

[0018] In a second aspect, the present application discloses a pressure detection device, which includes any one of the aforementioned MEMS pressure sensors.

[0019] For the above-mentioned MEMS pressure sensor and pressure detection device, since the first interconnection point and the second interconnection point are electrically connected in a direction perpendicular to the sensor sheet, the transmission channel of the original signal between the detection circuit and the signal processing circuit is short, so that the original signal is less interfered by external environmental noise during transmission, the anti-interference performance can be improved, and the signal is not easy to attenuate, thereby improving the performance of the device. Due to the improved anti-interference ability, the signal is less interfered by external environmental noise during the secondary transmission process (the ROIC output signal is then output to the circuit board functional unit through the signal transmission channel composed of WB wire bonding, tube shell pins, circuit board routing, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is an exploded view of a MEMS pressure sensor according to an embodiment of the present application;

[0021] Figure 2 is a schematic diagram of bonding a sensor sheet to a substrate to form a cavity;

[0022] Figure 3 is a schematic diagram of the sensor sheet;

[0023] Figure 4 yes Figure 3 A front view of the sensor sheet shown;

[0024] Figure 5 is a schematic diagram of the substrate;

[0025] Figure 6 is a schematic diagram of a signal processing circuit, a second interconnection point, and a pad;

[0026] Figure 7 is another schematic diagram of the sensor sheet and substrate bonding to form a cavity;

[0027] Figure 8 is a schematic diagram of the ROIC sheet formed with an insulating layer;

[0028] Fig. 9 is a schematic diagram of forming a pad, a second interconnection point, and a second solder;

[0029] Fig.10 is a schematic diagram of the sensor SOI chip;

[0030] Fig.11 It is a schematic diagram of forming a detection circuit on the sensor SOI chip;

[0031] Fig.12is a schematic diagram of forming a first interconnection point and a first solder on a sensor SOI wafer;

[0032] Fig.13 It is a schematic diagram of bonding the sensor sheet to the substrate;

[0033] Fig.14 is another schematic diagram of bonding the sensor sheet to the substrate. DETAILED DESCRIPTION

[0034] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0035] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. The words "first", "second" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantitative limit, but indicate that there is at least one. "Multiple" or "several" means two or more. Unless otherwise specified, words such as "front", "rear", "lower" and / or "upper" are only for the convenience of explanation and are not limited to one position or one spatial orientation. Words such as "include" or "comprise" mean that the elements or objects appearing in front of "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, and can include electrical connections, whether direct or indirect. The singular forms "a", "said" and "the" used in this specification and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] In order to solve the problem that the original signal of MEMS pressure sensor is easily interfered by the external environment during transmission, the inventor of this application found through research that in the existing pressure sensor, the signal is transmitted by routing on the surface of the pressure sensor and then along the side of the pressure sensor. In this way, the transmission channel of the original signal is longer. The longer transmission channel makes the original signal more susceptible to interference and attenuation. Based on this, the inventor of this application has developed a MEMS pressure sensor. The structure of the pressure sensor is described below in conjunction with the accompanying drawings.

[0037] See also Figure 1 Combined with Figure 2 and Figure 7 The embodiment of the present application discloses a MEMS pressure sensor. The MEMS pressure sensor includes a sensor sheet 100 and a substrate 200. Figure 3 and Figure 4 , the sensor sheet 100 includes a pressure sensing structure, a detection circuit connected to the pressure sensing structure, and a first interconnection point 4 connected to the detection circuit. The pressure sensing structure and the detection circuit are not limited to the structures described below. The pressure sensing structure is used to generate an original signal, and in the embodiment of the present application, includes a pressure sensitive membrane 21. The detection circuit is a Wheatstone bridge in this embodiment. In this embodiment, the MEMS pressure sensor is a piezoresistive MEMS pressure sensor. When the pressure sensitive membrane 21 is pressed, the pressure sensitive membrane 21 is deformed to generate an original signal. The original signal is detected by the Wheatstone bridge. Technicians can understand that for a capacitive pressure sensor or a resonant pressure sensor, the pressure sensing structure is the corresponding structure for the capacitive pressure sensor or the resonant pressure sensor to generate an original signal, such as a corresponding sensitive membrane, etc. Correspondingly, the detection circuit is not necessarily a Wheatstone bridge, as long as it can detect the original signal. The detection circuit includes a first trace 3. For the piezoresistive pressure sensor shown in the figure, the first wiring includes the connection between the piezoresistors 2. For the capacitive pressure sensor or the resonant pressure sensor, the first wiring 3 is the line for the detection circuit to output the signal to the signal processing circuit. The first interconnection point 4 is connected to the detection circuit, that is, the first interconnection point 4 is connected to the first wiring 3.

[0038] See also Figure 1 , Figure 5 and Figure 6, the substrate 200 includes a signal processing circuit 7 and a second interconnection point 10 connected to the signal processing circuit 7. How to construct the signal processing circuit 7 is not limited. In one embodiment of the present application, the signal processing circuit 7 is constructed as follows: the substrate 200 includes an ROIC sheet 6. The ROIC sheet 6 includes the signal processing circuit 7 inside, and the signal processing circuit 7 includes a signal processing element 70 and a corresponding second wiring. The second wiring includes a signal input wiring 71 between the signal processing circuit 7 and the detection circuit, a signal output wiring 72, a driving wiring 73 connecting the detection circuit, and a grounding wiring 74 that grounds the detection circuit and the signal processing circuit 7). For a more intuitive, Figure 1 The dashed lines indicate that the signal processing circuit (signal processing element 70 and the second routing) is located inside the ROIC sheet 6. The signal processing circuit 7 (signal processing element 70 and the second routing) can be arranged inside the ROIC sheet 6 in any manner, for example, the inside of the silicon sheet (not the surface of the silicon sheet) is made into the signal processing element 70 and the second routing by an integrated circuit process, so that the silicon sheet, the signal processing element 70 and the interconnecting routing constitute the ROIC sheet 6.

[0039] Based on the above structure, the second interconnection point 10 is connected to the signal processing circuit 7, that is, Figure 6 As shown, the second interconnection point 10 is correspondingly connected to a signal input line 71, a signal output line 72, a drive line 73 connected to a detection circuit, and a ground line 74. Of course, the structure of the second line is not limited to the above structure.

[0040] See also Figure 2 and Figure 7 Combined with Figure 1 The sensor sheet 100 and the substrate 200 are arranged opposite to each other, and the first interconnection point 4 is electrically connected to the second interconnection point 10 in a direction perpendicular to the sensor sheet 100. After the connection, the signal processing circuit 7 is connected to the detection circuit to transmit the driving signal to the detection circuit and the original signal detected by the detection circuit is transmitted to the signal processing circuit 7. The signal processing circuit 7 obtains the processing result. The processing result is transmitted to the outside through the signal output wiring 72. How to process is determined according to the function and is not limited to the amplification described in this application.

[0041] As described above, since the first interconnection point 4 and the second interconnection point 10 are electrically connected in a direction perpendicular to the sensor sheet 100, the transmission channel of the original signal between the detection circuit and the signal processing circuit is short, so that the original signal is less interfered by external environmental noise during transmission, the anti-interference performance can be improved, and the signal is not easy to attenuate, thereby improving the performance of the device. For example, at least the transmission channel can be shortened without routing from the surface of the sensor to the side. Due to the improved anti-interference ability, the signal is less interfered by external environmental noise during the secondary transmission process (the ROIC output signal is then output to the circuit board functional unit through the signal transmission channel composed of WB wiring, tube shell pins, circuit board routing, etc.), and the signal is not easy to attenuate.

[0042] See also Figure 2 and Figure 7 The sum of the height of the first interconnection point and the height of the second interconnection point is h, and h≤40um (micrometer).

[0043] As set above, the h≤40um also ensures that the signal transmission channel between the detection circuit and the signal processing circuit 7 is short. Therefore, the original signal is less interfered by the external environmental noise during transmission, the anti-interference performance is improved, the signal is not easily attenuated, and the device performance is improved.

[0044] In some embodiments, in combination Figure 1 The sensor sheet 100 includes a SOI buried oxide layer 11; the detection circuit and the first interconnection point 4 are formed on the surface of the SOI buried oxide layer 11; an insulating layer 8 is provided on the surface of the ROIC sheet 6, and the insulating layer 8 is provided with the second interconnection point 10. The SOI buried oxide layer 11 covers the insulating layer 8 on the ROIC sheet 6. How to cover is not limited to the following bonding method.

[0045] As described above, the SOI buried oxide layer 11 covers the insulating layer 8, and there is no other layer between the SOI buried oxide layer 11 and the insulating layer 8, which further minimizes the distance between the two in the direction perpendicular to the sensor sheet 100. As a result, the first interconnection point 4 and the second interconnection point 10 are shorter after being electrically connected, and the signal transmission channel between the detection circuit and the signal processing circuit is shorter. The original signal is less interfered by external environmental noise during transmission, which improves the anti-interference performance, and the signal is not easily attenuated, thereby improving the device performance. In addition, the detection circuit and the first interconnection point 4 are formed on the SOI buried oxide layer 11, an insulating layer is formed on the ROIC sheet 6, and the second interconnection point 10 is formed on the insulating layer. The first interconnection point 4 is connected to the second interconnection point 10 to realize the connection between the detection circuit and the signal processing circuit 7, and there is no need to prepare TSV, and the preparation process is also simple.

[0046] See also Figure 3 and Figure 4 Combined with Figure 1 The detection circuit is a Wheatstone bridge, and the first interconnection point 4 is correspondingly arranged at the intersection of each two adjacent bridge arms. Figure 3 , Figure 4 and Figure 1 In the figure, the Wheatstone bridge is in a square shape with four vertices, and each vertex is correspondingly provided with an interconnection point 4. Of course, the corresponding arrangement may be that the projection of the intersection point and the first interconnection point in the direction perpendicular to the sensor sheet 100 coincides, or the first interconnection point 4 is at a certain distance from the intersection point, but this distance is relatively small.

[0047] As described above, since the first interconnection point 4 is provided at the intersection of each two adjacent bridge arms, the wiring between the first interconnection point 4 and the detection circuit is shorter. Combined with the first interconnection point 4 and the second interconnection point 10 being connected in a direction perpendicular to the sensor sheet 100, the signal transmission channel between the detection circuit and the signal processing circuit 7 is shorter, and the original signal is less interfered by external environmental noise during transmission, thereby improving the anti-interference performance, and the signal is not easily attenuated, thereby improving the device performance.

[0048] See also Figure 2 Combined with Figure 1 , the sensor sheet 100 is arranged opposite to the substrate 200 to form a closed cavity 61. The first interconnection point 4, the first routing line 3, the second interconnection point 10 and the second routing line (signal input routing line 71, part of the signal output routing line 72, driving routing line 73 and ground routing line 74) are located in the cavity 61. Because the signal output routing line 72 needs to output the signal, there must be a section outside the cavity 61. Therefore, the aforementioned second routing line is located in the cavity 61, including the situation that part of the signal output routing line 72 is located in the cavity 61 and the other part of the signal output routing line is located in the cavity 61. In this embodiment, the electrical connection between the first interconnection point 4 and the second interconnection point 10 in the direction perpendicular to the sensor sheet 100 can be considered to be electrically connected in the depth direction of the cavity 61. In a further embodiment, the cavity 61 is a vacuum cavity, and the isolation effect of the vacuum cavity 61 is better, and thus, the signal is less interfered by environmental noise during transmission, and the signal is not easily attenuated.

[0049] As described above, since the first interconnection point 4, the first routing line 3, the second interconnection point 10 and the second routing line are located in the cavity 61, the transmission channel of the original signal is located in the cavity 61 formed by bonding and is isolated from the external environment. Therefore, the original signal is less disturbed by external environmental noise during transmission, the anti-interference ability of the signal is improved, and the signal is not easily attenuated. Due to the stronger anti-interference ability, the ROIC output signal is less disturbed by external environmental noise during the secondary transmission process (the ROIC output signal is then output to the circuit board functional unit through the signal transmission channel composed of WB wire bonding, tube shell pins, circuit board routing, etc.).

[0050] See also Figure 2 , Figure 2 The cavity 61 shown is a closed cavity and is an absolute pressure structure. Figure 7 See the gauge pressure configuration shown. Figure 7 As shown, a through hole 62 penetrating the ROIC sheet 6 is provided on the ROIC sheet 6. Thus, the cavity 61 is connected to the outside through the through hole 62. There is no requirement for the size of the through hole 62, which is generally 0 to 100 um. Of course, a major difference between the gauge pressure structure and the absolute pressure structure is the presence or absence of the through hole 62. Therefore, in the gauge pressure structure, the cavity 61 can also be formed by solder bonding as described later.

[0051] Compared with the absolute pressure structure, the cavity 61 of the gauge pressure structure still has an isolation effect (for example, it is difficult for external signals to enter the cavity 61 from the through hole 62), so it can still improve the anti-interference ability of the original signal, and the signal is not easy to attenuate. In addition, in the gauge pressure structure, the signal processing can still be completed inside the ROIC sheet 6, so the amplified signal is still transmitted to the outside, and the interference of external environmental noise on the signal during signal transmission can also be reduced, the anti-interference ability of the signal is improved, and the signal is not easy to attenuate.

[0052] See also Figure 6 and Figure 1 Combined with Figure 2 and Figure 7As mentioned above, the signal processing circuit 7 is arranged in the ROIC sheet 6, that is, the signal processing element 70 of the signal processing circuit 7 is located inside the ROIC sheet 6, so that the signal processing (at least including amplification in the embodiment of the present application, and also including differential for the piezoresistive pressure sensor) is completed inside the ROIC sheet 6, and the amplified signal is transmitted to the outside. As a result, the amplified signal has a stronger anti-interference ability, and is less interfered by external environmental noise during the secondary transmission process (the ROIC output signal is then output to the circuit board functional unit through the signal transmission channel composed of WB bonding, tube shell pins, circuit board routing, etc.), so the sensor performance can be improved. In addition, in the above design, part of the circuit functions (such as the differential amplification function of the signal processing element 70) are integrated into the micro-integrated circuit, thereby reducing the overall device volume and facilitating integration.

[0053] The following three conditions are met: 1) the first interconnection point 4 and the second interconnection point 10 are electrically connected in a direction perpendicular to the sensor sheet 100; 2) the first interconnection point 4, the first routing line 3, the second interconnection point 10 and the second routing line are located in the cavity 61 (including the aforementioned closed cavity 61 and the cavity 61 with the through hole 62); 3) when the interior of the ROIC sheet 6 includes the signal processing circuit 7, the original signal transmission channel is short and the transmission channel is located in the cavity 61 and isolated from the external environment, and the signal is processed (such as differential amplification) inside the ROIC sheet 6 and then output, therefore, the interference of external environmental noise on the signal during signal transmission can be reduced, the anti-interference ability of the signal is improved, and the signal is not easy to attenuate.

[0054] In the above-mentioned various corresponding embodiments, since the signal processing element 70 and the second routing (signal input routing 71, signal output routing 72, drive routing 73 and ground routing 74) of the signal processing circuit 7 are formed inside the ROIC sheet 6, and then the insulating layer 8 is provided, and the insulating layer 8 is opened to form the second interconnection point 10 in the opening area, there is no need to prepare TSV, and the preparation process is also simple. Furthermore, there is no MEMS structure on the ROIC sheet 6, and there is no need to perform a MEMS bulk silicon etching patterning process on the ROIC sheet 6, so the circuit can have a large area, so that more structures can be set, and the device performance can also be improved, for example, avoiding the mutual influence between the MEMS structure and the circuit, and for example, avoiding noise crosstalk.

[0055] See also Figure 1 A getter 13 is made on the upper surface of the ROIC sheet 6. The position of the getter 13 corresponds to the pressure sensitive film 21. The distance between the outer edge of the getter 13 and the second interconnection point 10 is greater than 50 um, which can ensure a safe distance and reliability.

[0056] The following describes the bonding method of the sensor sheet 100 and the substrate 200 in the present application:

[0057] See also Figure 3 and Figure 4 The sensor sheet 100 includes a sensor SOI sheet 1. The sensor SOI sheet 1 is provided with a first solder 51 in a ring shape (the first solder 51 surrounds the sensor SOI sheet 1 and is in a ring shape). Figure 3 As shown, the first interconnection point 4 is located in the area surrounded by the first solder. Figure 5 and Figure 1 The substrate 200 includes a second solder in an annular shape. In this embodiment, the substrate 200 includes a ROIC sheet 6, and the ROIC sheet 6 is provided with a second solder 52 in an annular shape. The first solder 51 and the second solder 52 may be eutectic solders, but are not limited thereto. Figure 5 As shown, the second solder 52 surrounds the ROIC sheet 6 and is in a ring shape. The second interconnection point 10 is located in the area surrounded by the second solder 52. Figure 2 , the position of the second solder 52 corresponds to the position of the first solder 51. One purpose of the corresponding is that the first solder 51 and the second solder 52 can be bonded, and this condition is satisfied. Figure 2 The position described in the figure corresponds to that the second solder 52 is located directly below the first solder 51. The ring shape is not limited. In this embodiment, the ring shape is a square. Figure 2 Combined with Figure 1 The sensor sheet 100 (sensor SOI sheet 1) and the substrate 200 (ROIC sheet 6) are bonded by the first solder 51 and the second solder 52 to form the cavity 61. Figure 7 As shown, for the gauge pressure structure, the cavity 61 can also be formed by bonding the first solder 51 and the second solder 52 as described above.

[0058] As described above, by bonding the first solder 51 and the second solder 52, the solder itself is used to enclose the cavity 61, and the cavity 61 does not need to be formed by etching or other methods. The process is simple and the cavity 61 is stable. In addition, the first interconnection point 4 is located in the area enclosed by the first solder 51, and the second interconnection point 10 is located in the area enclosed by the second solder 52, which is also conducive to the short signal transmission channel between the detection circuit and the signal processing circuit 7, the original signal is less interfered by the external environmental noise during the transmission process, the anti-interference performance is improved, the signal is not easy to attenuate, and the device performance is improved. In addition, it is conducive to the first interconnection point 4 and the second interconnection point 10 being located in the cavity 61 and isolated, the original signal is less interfered by the external environmental noise during the transmission process, and the signal is not easy to attenuate.

[0059] In the above manner, the sensor SOI sheet 1 is provided with a pressure sensing structure and a detection circuit, etc., and these structures face the ROIC sheet 6. The sensor SOI sheet 1 can be called a flip-chip integrated structure.

[0060] See also Figure 3 and Figure 4 , some other features of the first solder 51 are described as follows:

[0061] 1) The distance between the outer edge of the first solder 51 and the outer edge of the integrated circuit device is greater than 50 um;

[0062] 2) The distance between the inner edge of the first solder 51 and the first interconnection point 4 is greater than 50 um;

[0063] 3) The width of the first solder 51 is greater than 600 um, and the thickness of the first solder 51 is 10 to 60 um;

[0064] 4) The first solder 51 is formed on the surface of the SOI buried oxide layer 11 , located at the outer edge of the device and has no electrical connection with the first interconnection point 4 .

[0065] When at least one of the above characteristics is satisfied, when the distance between the outer edge of the first solder 51 and the outer edge of the integrated circuit device is greater than 50um, and / or the distance between the inner edge of the first solder 51 and the first interconnection point 4 is greater than 50um, a safe distance can be provided to ensure reliability. For example, if the distance is too small, the reliability will be affected due to solder overflow. When the first solder 51 meets the width and / or thickness, the size of the cavity 61 can be ensured, and bonding is facilitated, etc.

[0066] See also Figure 5 and Figure 1 , some other features of the second solder 52 are described as follows: the distance between the outer edge of the second solder 52 and the outer edge of the integrated circuit device is greater than 50um, the distance between the inner edge of the second solder 52 and the second interconnection point 10 is greater than 50um, the width of the second solder 52 is greater than 600um, and the thickness of the second solder 52 is 10-60um. When at least one of the above features is satisfied, when the distance between the outer edge of the second solder 52 and the outer edge of the integrated circuit device is greater than 50um, and / or the distance between the inner edge of the second solder 52 and the second interconnection point 10 is greater than 50um, a safe distance can be provided to ensure reliability. For example, if the distance is too small, the reliability will be affected due to solder overflow. When the first solder 51 meets the width and / or thickness, the size of the cavity 61 can be ensured, which is convenient for bonding, etc.

[0067] See also Figure 3 and Figure 4 Combined with Figure 1 and Figure 2The detection circuit includes a first interconnection point 4 connected to a first wiring 3, from Figure 1 The first interconnection point 4 can also be seen through the dotted line. In the embodiment of the present application, there are four first interconnection points 4, and the connection line of the four first interconnection points 4 forms a square. The height difference between the first interconnection point 4 and the first solder 51 is ±3um, which can also be understood as the height of the two is basically the same.

[0068] As set above, since the height difference between the first interconnection point 4 and the first solder 51 is ±3 um, the bonding strength and the interconnection reliability between the first interconnection point 4 and the second interconnection point 10 can be ensured.

[0069] See also Figure 2 and Figure 7 The height difference between the second interconnection point 10 and the second solder 52 is ±3 um, which can also be understood as the heights of the two being basically the same.

[0070] As configured above, since the height difference between the second interconnection point 10 and the second solder 52 is ±3 um, the bonding strength and the interconnection reliability between the second interconnection point 10 and the first interconnection point 4 can be ensured.

[0071] For the first interconnection point 4 and the second interconnection point 10 in the above-mentioned various embodiments, the first interconnection point 4 and the second interconnection point 10 may also include at least one of the following features:

[0072] 1) The first interconnection point 4 and the second interconnection point 10 are square, rectangular, circular, elliptical or other structures, and accordingly, the side length or diameter of the first interconnection point 4 is 50um to 100um;

[0073] 2) The material of the first interconnection point 4 and the second interconnection point 10 may be Au, AuSn, AgSn, CuSn, SnAgCu, etc.

[0074] When the first interconnection point 4 and the second interconnection point 10 meet one of the above characteristics, the conductivity is good and the original signal transmission is good.

[0075] In the above embodiment, the structures of the first interconnection point 4 and the second interconnection point 10 are not limited.

[0076] In the above embodiment, the first interconnection point 4 and the second interconnection point 10 are interconnected to realize that the original signal generated by the pressure sensing structure can be transmitted to the signal processing circuit 7. Figure 6 and Figure 4 A transmission method is described as follows: Figure 6 and Figure 4 The orientation in is used as a reference, and the connection relationship is as follows:

[0077] Upper left corner: pad 9, drive trace 73, second interconnection point 10 and first interconnection point 4 are connected;

[0078] Upper right corner: the second interconnection point 10 is connected to the first interconnection point 4, and the second interconnection point 10 is connected to the input end of the signal processing element 70 through the signal input wiring 71, and the output of the signal processing element 70 is connected to the pad 9 in the upper right corner through the output signal wiring 72;

[0079] Lower right corner: the second interconnection point 10 is connected to the first interconnection point 4, two signal processing components 70 are connected to the second interconnection point 10, and are connected to the pad 9 through the ground trace 74 in the lower right corner to the ground;

[0080] Lower left corner: the second interconnection point 10 is connected to the first interconnection point 4, and the second interconnection point 10 is connected to the input end of another signal processing element 70 through a signal input line 71, and the output of the signal processing element 70 is connected to the pad 9 in the lower left corner through an output signal line 72.

[0081] Based on the above connection relationship: the external driving signal is connected to the Wheatstone bridge (a kind of detection circuit) composed of the varistor 2 and the first wiring 3 through the pad 9 in the upper left corner → the second interconnection point 10 in the upper left corner → the first interconnection point 4 in the upper left corner to drive the sensor to work; after the pressure sensitive film 21 is pressed, the signal of the corresponding varistor 2 is transmitted to the outside through the first wiring 3 → the first interconnection point 4 in the upper right corner and the second interconnection point 10 in the upper right corner (the first interconnection point 4 in the lower left corner and the second interconnection point 10 in the lower left corner) → the signal input wiring 71 → the corresponding signal processing element 70 → the output signal wiring 72 and the corresponding pad 9 and the WB line. Specifically, the processing result of one signal processing element 70 is transmitted to the outside through the signal output wiring 72, the pad 9 in the upper right corner and the WB line, and the processing result of another signal processing element 70 is transmitted to the outside through the signal output wiring 72, the pad 9 in the lower left corner and the WB line.

[0082] Other features of the pad 9 are described as follows:

[0083] 1) The material of the pad 9 can be a low resistivity material such as Al, Ti / Al, Au, Cr / Au, etc. to form a good circuit path.

[0084] 2) The pad 9 is located at the periphery of the second solder 52 .

[0085] 3) The pad 9 can be in the shape of a square, rectangle, circle, oval, etc. The side length or straight dimension of the pad 9 is 50-150 um.

[0086] The above various embodiments mainly involve the transmission between the original signal detected by the detection circuit and the signal processing circuit 7. Therefore, the above various embodiments are applicable to piezoresistive pressure sensors, capacitive pressure sensors and resonant pressure sensors. As follows, some structures of the pressure sensing structure and the detection circuit when describing the piezoresistive pressure sensor.

[0087] See also Figure 1 , Figure 3 and Figure 4 , the pressure sensing structure includes a pressure sensitive film 21. The detection circuit is a Wheatstone bridge composed of a piezoresistor 2 and a first wiring 3 (of course, it can also be other structures as long as it can detect the original signal). For intuitiveness, Figure 1 The detection circuit (varistor 2 and pressure sensitive film 21) is also indicated by dotted lines. The varistor 2 can be a doped silicon varistor, a metal film varistor, etc. The sensor sheet 100 includes a sensor SOI sheet 1. The sensor SOI sheet 1 includes an SOI buried oxide layer 11 and an SOI substrate layer 12. The detection circuit (varistor 2 and the first wiring 3) and the first interconnection point 4 are formed on the surface of the SOI buried oxide layer 11. The first interconnection point 4 is connected to the first wiring 3 and the signal processing circuit (for example, connected to the signal processing circuit 7 through the second interconnection point 10), so that the first wiring 3 connects the first interconnection point 4 and the varistor 2 horizontally (that is, not in the thickness direction of the SOI buried oxide layer, but in the vertical direction).

[0088] As described above, since the varistor 2, the first wiring 3 and the first interconnection point 4 are formed on the surface of the SOI buried oxide layer 11, the first wiring 3 is not connected to the first interconnection point 4 in the thickness direction of the SOI buried oxide layer 11, and TSV does not need to be prepared, and the process is simple.

[0089] Some other features of the Wheatstone bridge are described as follows:

[0090] 1) The four varistors 2 are respectively located at the center position (which may be the center position or the center position ±50 um) of the membrane edge 211 of the pressure sensitive membrane 21;

[0091] 2) The distances between the four varistors 2 and the corresponding diaphragm edges 211 are kept consistent and the distance d is a value between 0 and 20 um.

[0092] 3) The width and total length of the four varistors 2 are the same, and the folding number can be 1 to 10;

[0093] 4) The Wheatstone bridge is square, and the structures of the varistors 2 at opposite positions are the same, for example, Figure 4The structures of the varistors 2 at the upper and lower relative positions are the same; the structures of the varistors 2 at the left and right relative positions are the same.

[0094] The Wheatstone bridge that meets one of the above characteristics can maximize the stress, high sensitivity, better linearity, and ultimately, better measured original signal.

[0095] Some features of the first routing line 3 are described as follows:

[0096] 1) The length of the first wiring 3 is less than 50 um, and the width of the first wiring 3 is less than 15 um, so as to reduce the total volume of the first wiring 3 on the surface of the SOI buried oxide layer 11;

[0097] 2) The first wiring 3 may be made of a low resistivity material such as Al, Ti / Al, Au, Cr / Au, etc., to form a good circuit path.

[0098] See also Figure 1 Combined with Figure 3 and Figure 4 The pressure sensing structure includes a pressure sensitive film 21, and the sensor SOI sheet 1 includes an SOI substrate layer 12; the SOI substrate layer 12 is etched to form a cavity to form the pressure sensitive film; the cavity penetrates the SOI substrate layer 12, for example, penetrates the SOI substrate layer 12 to the SOI buried oxide layer 11, or, during etching, does not penetrate the SOI substrate layer 12, so that the depth of the cavity is less than the thickness of the SOI substrate layer 12. Figure 1 , Figure 3 and Figure 4 It is shown that the projection of the cavity on a plane parallel to the SOI substrate layer 12 is a square. Of course, in some embodiments, the projection may also be a circle.

[0099] As configured above, when the projection is a square or a circle, this shape can make the stress of the pressure sensitive film large and the sensitivity high.

[0100] In the above embodiment, see Figure 4 Combined with Figure 3 The first interconnection point 4 is located outside the membrane edge 211 of the pressure sensitive membrane 21, and the distance e between the first interconnection point 4 and the corresponding membrane edge of the pressure sensitive membrane 21 is 10um to 50um.

[0101] As described above, since the first interconnection point 4 is located outside the membrane edge 211 of the pressure sensitive membrane 21, and the distance e from the membrane edge corresponding to the pressure sensitive membrane 21 is 10um to 50um, the hysteresis of the signal can be reduced and the performance index of the pressure sensor can be improved. Of course, because the first interconnection point 4 is close to the detection circuit, combined with the electrical connection between the first interconnection point 4 and the second interconnection point 10 in a direction perpendicular to the sensor sheet 100, the signal transmission channel between the detection circuit and the signal processing circuit 7 can be shortened, the anti-interference ability is improved, and the signal is not easy to attenuate.

[0102] In a second aspect, the embodiments of the present application further disclose a pressure detection device. The pressure detection device includes any of the aforementioned MEMS pressure sensors. The pressure detection device can be used to detect the pressure of oil pipelines, tire pressure, etc. The MEMS pressure sensor can adopt any structure and other components to form the pressure detection device, which will not be described in detail.

[0103] In a third aspect, an embodiment of the present application discloses a method for manufacturing a MEMS pressure sensor, the method comprising the following steps:

[0104] See also Figure 8 , S1: forming a substrate 200, including: forming a signal processing circuit 7 inside a silicon wafer to form a ROIC wafer 6, Figure 8 In the figure, only the dashed line is used to represent the signal processing circuit 7 inside the silicon chip. A second interconnection point 10 connected to the signal processing circuit 7 is formed on the ROIC chip.

[0105] See also Fig.10 and Fig.11 S2: forming a sensor sheet 100, including: forming a pressure sensing structure, a detection circuit connected to the pressure sensing structure, and a first interconnection point 4 connected to the detection circuit on the sensor SOI sheet 1. The order of the steps of forming the sensor sheet 100 and forming the substrate 200 is not limited.

[0106] S3: The sensor sheet and the substrate are arranged relative to each other, and the first interconnection point and the second interconnection point are electrically connected in a direction perpendicular to the sensor sheet. There is no limitation on how to arrange them relative to each other, for example, the relative arrangement is achieved by bonding as mentioned above.

[0107] The manufacturing method is simple to form the MEMS pressure sensor. In the manufactured MEMS pressure sensor, the first interconnection point 4 and the second interconnection point 10 are electrically connected in a direction perpendicular to the sensor sheet 100, so that the transmission channel of the original signal between the detection circuit and the signal processing circuit is short, so that the original signal is less interfered by the external environmental noise during transmission, the anti-interference performance can be improved, the signal is not easy to attenuate, and the device performance is improved. In addition, the signal processing circuit 7 is formed inside the ROIC sheet 6, so that the signal processing is completed inside the ROIC sheet 6, and the amplified signal is transmitted to the outside world. The signal transmission is isolated from the outside world and the amplified signal is transmitted to the outside world. In the secondary transmission process (the ROIC output signal is then output to the circuit board function unit through the signal transmission channel composed of WB wire bonding, tube shell pins, circuit board routing, etc.), it is less interfered by the external environmental noise and the signal is not easy to attenuate. In addition, in the above design, part of the circuit functions (such as the differential amplification function of the signal processing element 70) are integrated into the micro integrated circuit, thereby reducing the overall device volume and facilitating integration.

[0108] See also Fig.10 and Fig.11 The sensor SOI sheet 1 includes an SOI buried oxide layer 11 and an SOI substrate layer 12. Forming the sensor sheet includes: forming the piezoresistor 2, the first wiring 3 and the first interconnection point 4 on the surface of the SOI buried oxide layer 11; the detection circuit includes the piezoresistor 2 and the first wiring 3. Etching the SOI substrate layer 12 to form the pressure sensitive film 21.

[0109] As described above, in this method, because the piezoresistor 2 and the first wiring 3 are formed on the SOI buried oxide layer 11 of the sensor SOI sheet 1, the piezoresistor 2 and the first wiring 3 constitute a detection circuit, and the pressure sensitive film 21 is formed on the SOI substrate layer 12, so that the first wiring 3 is not connected to the first interconnection point 4 in the thickness direction of the SOI buried oxide layer 11, and TSV does not need to be prepared, and the process is simple. Moreover, in the above method, the detection circuit and the first interconnection point 4 are formed on the SOI buried oxide layer 11, and the pressure sensitive film 21 is formed on the SOI substrate layer 12, and the sensor sheet 100 is easy to manufacture.

[0110] In some embodiments, see Fig. 9 Combined with Figure 8 The formation of the substrate includes: forming an insulating layer 8 on the surface of the ROIC sheet 6, opening holes in the insulating layer 8 and setting pads 9 and second interconnection points 10 in the corresponding holes; the pads 9 are connected to the signal processing circuit 7.

[0111] As described above, it is only necessary to form the pad 9, the second interconnection point 10, the first interconnection point 4 and the detection circuit on the corresponding surface, so that the manufacturing process is simple. For example, the connection between the first interconnection point 4 and the first wiring 3 does not require the production of TSV and the process is simple. In addition, there is no MEMS structure on the ROIC sheet 6, and there is no need to perform a MEMS bulk silicon etching patterning process on the ROIC sheet 6. Therefore, the circuit can have a large area, so that more structures can be set, and the device performance can be improved, for example, avoiding the mutual influence between the MEMS structure and the circuit, and for example, avoiding noise crosstalk.

[0112] In some embodiments, the manufacturing method includes: forming a closed cavity between the sensor sheet and the substrate; the detection circuit includes a first routing line connected to the first interconnection point; the signal processing circuit includes a second routing line connected to the second interconnection point, and the first interconnection point, the first routing line, the second interconnection point and the second routing line are all located in the cavity.

[0113] In the above manufacturing method, the first interconnection point, the first routing line, the second interconnection point and the second routing line are all located in the cavity and isolated from the external environment. Therefore, the interference of external environmental noise on the signal during signal transmission can be reduced, the anti-interference ability of the signal is improved, and the signal is not easily attenuated.

[0114] See also Fig. 9 and Fig.12 , the closed cavity comprises:

[0115] A first solder 51 in the shape of a ring is formed on the sensor SOI sheet 1 (specifically on the SOI buried oxide layer 11). The first solder 51 is, for example, a eutectic solder. The first interconnection point 4 is located in the area surrounded by the first solder; a second solder 52 in the shape of a ring is formed on the ROIC sheet 6. The second solder 52 can be a eutectic solder. The second interconnection point 10 is located in the area surrounded by the second solder 52.

[0116] See also Fig.13 The first solder 51 and the second solder 52 are bonded to form a closed cavity 61. Because the cavity 61 is closed, this structure is called an absolute pressure structure.

[0117] As described above, the cavity 61 is formed by a bonding process, which also makes the manufacturing method of the MEMS pressure sensor simple. In addition, the cavity 61 is surrounded by the solder itself, and the cavity 61 does not need to be formed by etching or the like. The process is simple, the cavity 61 is stable, and the electrical connection between the first interconnection point 4 and the second interconnection point 10 is achieved in a simple manner.

[0118] See also Fig.14The present application also discloses a method for manufacturing a MEMS pressure sensor having a gauge pressure structure. The manufacturing method comprises:

[0119] The manufacturing method includes: the sensor sheet and the substrate are arranged relative to each other to form a cavity 61 with a through hole 62, and the cavity 61 is connected to the outside through the through hole 62; the detection circuit includes a first routing line 3 connected to the first interconnection point 4; the signal processing circuit 7 includes a second routing line connected to the second interconnection point 10, and the first interconnection point 4, the first routing line 3, the second interconnection point 10 and the second routing line are all located in the cavity 61.

[0120] In the above manufacturing method, the first interconnection point, the first routing line, the second interconnection point and the second routing line are all located in the cavity and isolated from the external environment. Therefore, the interference of external environmental noise on the signal during signal transmission can be reduced, the anti-interference ability of the signal is improved, and the signal is not easily attenuated.

[0121] The cavity 61 having the through hole 62 is formed by the following steps: forming an insulating layer 8 on the surface of the ROIC sheet 6, and forming a through hole 62 penetrating the ROIC sheet 6 and the insulating layer 8; the through hole 62 can be formed in any step.

[0122] A first solder 51 in the shape of a ring is formed on the sensor SOI sheet 1. As mentioned above, the first solder 51 may be a eutectic solder. The first interconnection point 4 is located in the area surrounded by the first solder 51; a second solder 52 in the shape of a ring is formed on the ROIC sheet 6. As mentioned above, the second solder 52 may be a eutectic solder. The second interconnection point 10 is located in the area surrounded by the second solder 52, and the position of the second solder 52 corresponds to the position of the first solder;

[0123] The first solder 51 and the second solder 52 are bonded to form the cavity 61 , and the cavity 61 is connected to the outside through the through hole 62 ; accordingly, the detection circuit includes a first wiring 3 , a first interconnection point 4 , a second interconnection point 10 and a second wiring located in the cavity 61 .

[0124] Compared with the above-mentioned method for forming an absolute pressure structure, this manufacturing method only has an additional step of forming a through hole 62. Therefore, other beneficial effects are the same as those of the insulating structure and will not be described in detail.

[0125] The above description is only a preferred implementation mode of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A MEMS pressure sensor, characterized in that: The MEMS pressure sensor comprises a sensor sheet and a substrate, wherein; The sensor sheet includes a pressure sensing structure, a detection circuit connected to the pressure sensing structure, and a first interconnection point connected to the detection circuit; The substrate is provided with a signal processing circuit and a second interconnection point connected to the signal processing circuit; The sensor sheet and the substrate are arranged opposite to each other, and the first interconnection point and the second interconnection point are electrically connected in a direction perpendicular to the sensor sheet.

2. The MEMS pressure sensor according to claim 1, characterized in that: The sum of the height of the first interconnection point and the height of the second interconnection point is h, and h≤40 um.

3. The MEMS pressure sensor according to claim 1 or 2, characterized in that: The sensor sheet includes a SOI buried oxide layer; the detection circuit and the first interconnection point are formed on the surface of the SOI buried oxide layer; the substrate includes a ROIC sheet, an insulating layer is arranged on the surface of the ROIC sheet, and the second interconnection point is arranged on the insulating layer; The SOI buried oxide layer covers the insulating layer on the ROIC sheet.

4. The MEMS pressure sensor according to claim 1, characterized in that: The detection circuit is a Wheatstone bridge, and the first interconnection point is correspondingly arranged at the intersection of each two adjacent bridge arms.

5. The MEMS pressure sensor according to claim 1, characterized in that: The sensor sheet is arranged opposite to the substrate to form a closed cavity, the detection circuit includes a first wiring connected to the first interconnection point; the signal processing circuit includes a second wiring connected to the second interconnection point, and the first interconnection point, the first wiring, the second interconnection point and the second wiring are all located in the cavity; Alternatively, the sensor sheet and the substrate are arranged relative to each other to form a cavity with a through hole, the cavity is connected to the outside through the through hole, the detection circuit includes a first routing line connected to the first interconnection point; the signal processing circuit includes a second routing line connected to the second interconnection point, and the first interconnection point, the first routing line, the second interconnection point and the second routing line are all located in the cavity.

6. The MEMS pressure sensor according to claim 1, characterized in that: The substrate includes a ROIC sheet, and the interior of the ROIC sheet includes the signal processing circuit; the signal processing circuit at least amplifies the original signal generated by the pressure sensing structure.

7. The MEMS pressure sensor according to claim 1, characterized in that: The sensor sheet includes a first solder in an annular shape, and the first interconnection point is located in an area surrounded by the first solder; the substrate includes a second solder in an annular shape, and the second interconnection point is located in an area surrounded by the second solder, and the position of the second solder corresponds to the position of the first solder; The sensor sheet and the substrate are bonded by the first solder and the second solder.

8. The MEMS pressure sensor according to claim 7, characterized in that: The height difference between the first interconnection point and the first solder is ±3 um; And / or, a height difference between the second interconnection point and the second solder is ±3 um.

9. The MEMS pressure sensor according to claim 1, characterized in that: The sensor sheet includes an SOI substrate layer and an SOI buried oxide layer on which the detection circuit is arranged; the SOI substrate layer is etched to form a cavity to form a pressure sensitive film of the pressure sensing structure; The cavity passes through the SOI substrate layer to the buried oxide layer, or the depth of the cavity is less than the thickness of the SOI substrate layer.

10. The MEMS pressure sensor according to claim 9, characterized in that: The projection of the cavity on a plane parallel to the SOI substrate layer is a square or a circle.

11. The MEMS pressure sensor according to claim 9, characterized in that: The first interconnection point is located outside the membrane edge of the pressure sensitive membrane, and the distance from the corresponding membrane edge of the pressure sensitive membrane is 10 um to 50 um.

12. A pressure detection device, characterized in that: The pressure detection device comprises the MEMS pressure sensor according to any one of claims 1 to 11.

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