Pressure sensor, pressure sensor chip and method for manufacturing the same

Abstract

The application discloses a pressure sensor, a pressure sensor chip and a manufacturing method thereof. The pressure sensor chip comprises a substrate, and the substrate comprises a first surface and a second surface opposite to each other. A pressure sensing functional area is arranged on one side of the substrate close to the first surface, and the pressure sensing functional area comprises a plurality of pressure sensitive resistors, a plurality of conductive plates and a vacancy. The vacancy is located between the pressure sensitive resistors and between the conductive plates, and two ends of the pressure sensitive resistor are electrically connected with the conductive plate. The pressure sensing functional area of the application is not easily affected by a high-temperature environment in a manufacturing process, and the problem that the pressure sensing functional area fails due to high temperature is solved.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical technology, and in particular to a pressure sensor, a pressure sensor chip, and a method for manufacturing the same. Background Technology

[0002] A pressure sensor is a device that converts pressure signals into electrical signals. A pressure sensor generally consists of three parts: a pressure-sensitive chip, a processing circuit, and a package. The pressure-sensitive chip is the core component that directly senses the pressure signal. Based on their operating principle, pressure-sensitive chips can be classified into four main types: piezoresistive, capacitive, resonant, and piezoelectric. Among these, piezoresistive pressure-sensitive chips offer advantages such as high stability, low manufacturing cost, and compatibility with CMOS technology. Compared to the other three types, piezoresistive pressure-sensitive chips have a more significant overall advantage.

[0003] Currently, pressure sensor chips suffer from low yield rates during the manufacturing process. Summary of the Invention

[0004] The purpose of this application is to provide a pressure sensor with high manufacturing yield, a pressure sensor chip, and a method for manufacturing the same.

[0005] This application discloses a pressure sensor chip, which includes:

[0006] A substrate, the substrate comprising opposing first and second surfaces;

[0007] A pressure-sensing functional area is provided on one side of the substrate near the first surface. The pressure-sensing functional area includes a plurality of varistors, a plurality of conductive plates, and a gap. The gap is located between the varistors and between the conductive plates, and the two ends of the varistors are electrically connected to the conductive plates.

[0008] Optionally, a pressure chamber is provided on the second side of the substrate, and the pressure sensor chip includes an encapsulation structure located on the second side; the encapsulation structure seals the pressure chamber.

[0009] Optionally, the average ion concentration of the pressure-sensitive functional area is greater than or equal to 1*e^15 / cm^2 and less than or equal to 3*e^15 / cm^2.

[0010] Optionally, a pressure cavity is provided on the second surface of the substrate. The pressure cavity is frustum-shaped, with the top or bottom of the frustum located on the side close to the varistor.

[0011] Optionally, the varistor and the conductive plate are provided with an upper sealing cover on the side away from the substrate, and the upper sealing cover includes a first sealing cavity corresponding to the varistor.

[0012] Optionally, the maximum distance between two of the plurality of varistors is less than the width of the pressure cavity on the side closest to the varistor, and the width of the pressure cavity on the side closest to the varistor is less than the width of the first sealing cavity.

[0013] Optionally, the depth of the pressure-sensitive functional area is greater than or equal to 0.4 micrometers and less than or equal to 1.5 micrometers, and the edge of the pressure-sensitive functional area gradually contracts inward from the first surface to the direction away from the first surface, with a contraction angle greater than or equal to 35° and less than or equal to 55°.

[0014] Optionally, the substrate includes an isolation layer, and the pressure-sensitive functional area is formed on the side of the isolation layer near the first surface.

[0015] Optionally, the sheet resistance of the pressure-sensing functional area of ​​the pressure sensor chip is greater than or equal to 45Ω / square and less than or equal to 55Ω / square, the junction depth of the pressure-sensing functional area of ​​the pressure sensor chip is greater than or equal to 0.4 micrometers and less than or equal to 1.5 micrometers, and the average concentration of the pressure-sensing functional area of ​​the pressure sensor chip is greater than or equal to 1*e^15 / cm^3 and less than or equal to 3*e^15 / cm^3.

[0016] This application also discloses a method for manufacturing a pressure sensor chip, which includes:

[0017] Prepare a substrate, the substrate comprising a first surface and a second surface opposite to each other;

[0018] A mask is coated on the first surface of the substrate;

[0019] Pattern the mask on the first surface and form a barrier layer on the first surface;

[0020] An implantation layer is formed on the first surface by an ion implantation process;

[0021] The blocking layer is removed and the injection layer is etched to form a pressure-sensitive functional area, which includes a plurality of piezoresistors, a conductive plate and a void.

[0022] A pressure cavity is formed on the second surface by etching;

[0023] Manufacturing electrodes and packaging structures.

[0024] This application also discloses a pressure sensor, which includes the pressure sensor chip described above.

[0025] Compared with related technologies, the pressure-sensing functional area of ​​this application is less affected by the high-temperature environment during the manufacturing process, thus solving the problem of pressure-sensing functional area failure due to high temperature.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this specification. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this specification and, together with the description, serve to explain the principles of this specification.

[0028] Figure 1-11 This is a process diagram illustrating a method for manufacturing a pressure sensor chip according to an embodiment of this application.

[0029] Figure 12 This is a partial schematic diagram of a pressure sensor chip provided in an embodiment of this application.

[0030] Figure 13 This is a partial schematic diagram of a pressure sensor chip provided in an embodiment of this application.

[0031] Figure 14 This is a cross-sectional schematic diagram of a pressure sensor chip provided in an embodiment of this application.

[0032] Figure 15 This is a cross-sectional schematic diagram of a pressure sensor chip provided in an embodiment of this application.

[0033] Figure 16 This is a cross-sectional schematic diagram of a pressure sensor chip provided in an embodiment of this application.

[0034] Figure 17 This is a cross-sectional schematic diagram of a pressure sensor chip provided in an embodiment of this application. Detailed Implementation

[0035] The technical solutions in the embodiments (or "implementations") of this application will be clearly and completely described herein with reference to the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.

[0036] If the embodiments of this application contain terms relating to directional indications or positional relationships (such as up, down, left, right, front, back, inside, outside, top, bottom, center, vertical, horizontal, longitudinal, transverse, length, width, counterclockwise, clockwise, axial, radial, circumferential, etc.), such terms are only used to explain the relative positional relationships and movements between components in a specific posture (as shown in the attached figures); if the specific posture changes, the directional indications or positional relationships will also change accordingly. Furthermore, the terms "first" and "second" used in the embodiments of this application are only for descriptive convenience and should not be construed as indicating or implying relative importance.

[0037] like Figures 1 to 12 As shown, this application provides a pressure sensor chip, which includes:

[0038] The substrate 10 includes a first surface and a second surface facing each other.

[0039] A pressure-sensing functional area 41 is provided on one side of the substrate 10 near the first surface. The pressure-sensing functional area 41 includes a plurality of varistors 50, a plurality of conductive plates 60, and a gap 42. The gap 42 is located between the varistors 50 and between the conductive plates 60. The two ends of the varistors 50 are electrically connected to the conductive plates 60.

[0040] The pressure-sensing functional area of ​​this application is not easily affected by the high-temperature environment during the manufacturing process, thus solving the problem of pressure-sensing functional area failure due to high temperature.

[0041] The following will provide a detailed description of various embodiments of this application that conform to the above-described inventive concept.

[0042] like Figure 1 As shown, the method for manufacturing a sensor chip provided in this application includes preparing a substrate 10. The substrate 10 includes a first side and a second side facing each other. In this embodiment, the first side is the upper side of the substrate 10, and the second side is the lower side of the substrate 10. The substrate 10 can be a silicon substrate. After the substrate 10 is prepared, a mask 20 is coated on the first and second sides of the substrate 10. In some optional embodiments, the mask 20 may be coated only on the first side of the substrate 10. Optionally, the mask 20 may include two layers: a silicon oxide layer and a silicon nitride layer, wherein the silicon oxide layer is located on the side of the silicon nitride layer closest to the substrate 10. The mask 20 can be coated by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition). Optionally, the coating temperature of the mask 20 is greater than or equal to 900°C and less than or equal to 1200°C. In this embodiment, the coating temperature of the mask 20 is approximately 1000°C. The humidity of the mask 20 is greater than or equal to... Less than or equal to In this way, the mask 20 can both fulfill its function and prevent the substrate 10 from tearing.

[0043] like Figure 2 and Figure 3 as well as Figure 10As shown, after the mask 20 is coated, it is first patterned on the first surface of the substrate 10 using a patterning process. The patterning process includes removing a portion of the mask 20 from the middle region of the first surface of the substrate 10. In this embodiment, the top surface of the substrate 10 is approximately square, and the patterning process includes removing a portion of the mask 20 from the middle region of the first surface of the substrate 10 to form a square void area. The distance D between the edge of this square void area and the edge of the substrate 10 is approximately 1 micrometer. After the mask 20 is patterned, a barrier layer 30 is formed on the first surface of the substrate 10. In this embodiment, the barrier layer 30 is formed by filling the square void area formed by the patterning of the mask 20. The barrier layer 30 can be made of silicon oxide.

[0044] like Figure 4 as well as Figure 13 As shown, after forming the barrier layer 30, an implantation layer 40 is formed on the first surface of the substrate 10 by ion implantation. The implanted ions can be boron or phosphorus, etc. Optionally, the average ion implantation energy can be greater than or equal to 14 keV and less than or equal to 35 keV, and the average ion concentration can be greater than or equal to 1*e^15 / cm^2 and less than or equal to 3*e^15 / cm^2. In the embodiment of this application, the average ion implantation energy is 30 keV and the average ion concentration is 2.1*e^15 / cm^2. Thus, an implantation layer 40 with a sheet resistance greater than or equal to 45 Ω / square and less than or equal to 55 Ω / square, a junction depth b1 greater than or equal to 0.4 μm and less than or equal to 1.5 μm, and an average concentration greater than or equal to 1*e^15 / cm^3 and less than or equal to 3*e^15 / cm^3 can be obtained. Optionally, the edge of the implantation layer 40 gradually tapers inward from the first surface to the direction away from the first surface, and the taper angle a1 is greater than or equal to 35° and less than or equal to 55°. Since the junction depth b1 is greater than or equal to 0.4 micrometers and less than or equal to 1.5 micrometers, and the contraction angle a1 is greater than or equal to 35° and less than or equal to 55°, the width c1 of the invalid region at the edge of the injection layer 40 is about 0.3 micrometers to 2 micrometers. This parameter improves the electrical connection between the conductive plate 60 and the electrode 80, and enhances the working performance of the pressure sensor chip.

[0045] Finally, an annealing process is performed to activate the ions implanted into the substrate 10.

[0046] like Figure 5 as well as Figure 6 As shown, after the implantation layer 40 is formed, the barrier layer 30 is removed, exposing the implantation layer 40 to the upper surface of the substrate 10. The implantation layer 40 is then etched to form the pressure-sensitive functional region 41. The pressure-sensitive functional region 41 includes several piezoresistors 50, a conductive plate 60, and a void portion 42. Please also refer to... Figure 12In this embodiment, there are four varistors 50 and four conductive plates 60. The four conductive plates 60 are located at the four corners of the square empty area patterned by the mask 20. Adjacent conductive plates 60 are connected by a varistor 50, with the remaining portion being an empty section 42, thus forming a Wheatstone bridge. Each varistor 50 consists of several varistor strips connected end-to-end. Except for the connecting portions, each varistor strip has an empty section 42. The connected varistor strips form a serpentine structure, with each strip forming an angle greater than or equal to 89° and less than or equal to 91° with respect to the substrate 10.

[0047] like Figure 7 As shown, after etching the varistor 50 and the conductive plate 60, an electrode 80 is fabricated on the side of the conductive plate 60 away from the substrate 10. Each conductive plate 60 has one electrode 80. The electrode 80 can be cylindrical, cuboid, or frustum-shaped, etc. The material of the electrode 80 can be copper, aluminum, or an alloy, etc.

[0048] like Figure 8 and Figure 9 As shown, after the electrode 80 is fabricated, a pressure cavity 70 is formed on the second surface of the substrate 10 by etching. In this embodiment, a mask 20 is provided on the second surface of the substrate 10. The mask 20 located on the second surface of the substrate 10 can be etched first to pattern the mask 20, and a portion of the mask 20 in the middle region of the second surface of the substrate 10 is removed to form a square void area. Then, this portion of the area is wet-etched to form the pressure cavity 70. Afterward, the masks 20 located on the first and second surfaces of the substrate 10 are removed.

[0049] like Figure 10 As shown, after forming the pressure chamber 70, an upper sealing cover 110 is manufactured on the first surface of the substrate 10. In this embodiment, the upper sealing cover 110 is located above the substrate 10 and covers the conductive plate 60 and the varistor 50. The upper sealing cover 110 exposes the electrode 80 in the vertical direction. Specifically, the upper sealing cover 110 can be made of glass. The edge of the upper sealing cover 110 is aligned with the edge of the substrate 10. The upper sealing cover 110 has a through hole at the position of the electrode 80 to connect the electrode 80 and the top of the upper sealing cover 110. The upper sealing cover 110 includes a first sealing cavity 111 corresponding to the varistor 50. The first sealing cavity 111 is located on the side of the upper sealing cover 110 close to the varistor 50. The first sealing cavity 111 can be a cuboid cavity. The varistor 50 is located in the first sealing cavity 111, and at least a portion of the conductive plate 60 is located in the first sealing cavity 111.

[0050] like Figure 11As shown, after the upper sealing cap 110 is formed, conductive material is filled into the through hole connecting the electrode 80 and the top of the upper sealing cap 110, as well as the area surrounding the top of the through hole, to form a lead 90. The conductive material can be copper, aluminum, or a conductive alloy, etc. The conductive material can be filled using techniques such as PVD or electroplating.

[0051] like Figure 14 As shown, in an optional embodiment, a lower sealing cap 120 can be bonded to the second surface of the substrate 10 to seal the pressure chamber 70. Specifically, the edge of the lower sealing cap 120 can be aligned with the edge of the substrate 10, and the side of the lower sealing cap 120 near the substrate 10 corresponds in shape and fits snugly to the side of the substrate 10 near the lower sealing cap 120. The portion of the lower sealing cap 120 near the pressure chamber 70 can be provided with a cavity structure protruding away from the substrate 10 to increase the volume of the pressure chamber 70. After the pressure chamber 70 is sealed, it is less affected by noise, which can effectively improve the performance of the product.

[0052] like Figure 15 As shown, in an optional embodiment, during the manufacturing process, both the first and second surfaces of the substrate 10 are provided with masks 20. Figures 8 to 9 During the process, when removing the mask 20, only the mask 20 located on the second surface of the substrate 10 can be removed, while the mask 20 located on the first surface of the substrate 10 can be left unremoved. In this way, one step can be reduced, saving production time.

[0053] like Figure 16 As shown, in an optional embodiment, during the manufacturing process, when coating the mask 20, the mask 20 can be coated only on the first surface of the substrate 10 and not on the second surface of the substrate 10. After the electrode 80 is fabricated, a pressure cavity 70 can be formed on the second surface of the substrate 10 by dry etching. Thus, during the production process, the mask 20 does not need to be coated on the second surface of the substrate 10, and the mask 20 patterning and etching steps can be saved during etching, thus saving production time.

[0054] Whether formed by wet or dry etching, the pressure cavity 70 can be cylindrical, cuboid, or frustum-shaped. When the pressure cavity 70 is frustum-shaped, such as... Figure 15 as well as Figure 16 As shown, the top or bottom of the frustum is located on the side close to the varistor 50.

[0055] like Figure 10 As shown, in an optional embodiment, the maximum distance between two varistor 50 is less than the width of the pressure cavity 70 near the varistor 50, and the width of the pressure cavity 70 near the varistor 50 is less than the width of the first sealing cavity 111. Specifically, as... Figure 10As shown, in this embodiment, the farthest distance between two opposing varistors 50 among the four varistors 50 is A. The width of the pressure cavity 70 on the side closest to the varistor 50 is B. The width of the first sealing cavity 111 is C, where C > B > A. C > B ensures that the effective pressure-sensitive diaphragm layer of the pressure sensor is sealed within the first sealing cavity 111. B > A ensures that the varistor 50 is within the effective pressure-sensitive diaphragm layer range of the pressure sensor.

[0056] like Figure 17 As shown, in an optional embodiment, the substrate 10 includes an isolation layer 11, and an injection layer 40 is formed on the side of the isolation layer 11 near the first surface. For example, in this embodiment, the width of the injection layer 40 is set to 1 micrometer, and the isolation layer 11 is provided at a depth of 1 micrometer from the first surface of the substrate 10 towards the second surface. Thus, combined with Figure 4 When the implanted layer 40 is formed on the first surface of the substrate 10 by ion implantation, the thickness of the implanted layer 40 can be effectively controlled because there is a barrier layer 30 on one side of the implanted layer 40 close to the first surface and an isolation layer 11 on the other side, thus ensuring the quality of the product.

[0057] In one optional embodiment, the sheet resistance of the injection layer of the pressure sensor chip is greater than or equal to 45 Ω / square and less than or equal to 55 Ω / square, the junction depth of the injection layer of the pressure sensor chip is greater than or equal to 0.4 micrometers and less than or equal to 1.5 micrometers, and the average concentration of the injection layer of the pressure sensor chip is greater than or equal to 1*e^15 / cm^3 and less than or equal to 3*e^15 / cm^3. Specifically, in the embodiment of this application, the sheet resistance of the injection layer of the pressure sensor chip is 50 Ω / square, the junction depth of the injection layer of the pressure sensor chip is 1 micrometer, and the average concentration of the injection layer of the pressure sensor chip is 2.1*e^15 / cm^3.

[0058] like Figures 1 to 12 As shown, this application also provides a method for manufacturing a pressure sensor chip, which includes:

[0059] Prepare a substrate 10, which includes a first surface and a second surface facing each other.

[0060] A mask 20 is coated on the first surface of the substrate 10.

[0061] The mask 20 on the first surface is patterned and a barrier layer 30 is formed on the first surface.

[0062] An implantation layer 40 is formed on the first surface by an ion implantation process.

[0063] The barrier layer 30 is removed and the injection layer 40 is etched to form a pressure-sensitive functional area 41, which includes a plurality of piezoresistors 50, a conductive plate 60 and a void portion 42.

[0064] A pressure chamber 70 is formed on the second surface by etching.

[0065] Manufacturing electrode 80 and packaging structure.

[0066] This application also discloses a pressure sensor, which includes the pressure sensor chip described above.

[0067] It should be noted that the technical solutions or features described in the above embodiments can be combined or supplemented with each other without conflict. The scope of protection of this application is not limited to the precise structures described in the above embodiments and shown in the accompanying drawings; all modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A pressure sensor chip, characterized in that, include: A substrate, the substrate comprising opposing first and second surfaces; A pressure-sensing functional area is provided on one side of the substrate near the first surface. The pressure-sensing functional area includes a plurality of varistors, a plurality of conductive plates, and a gap. The gap is located between the varistors and between the conductive plates, and the two ends of the varistors are electrically connected to the conductive plates.

2. The pressure sensor chip according to claim 1, characterized in that, A pressure chamber is provided on the second side of the substrate, and the pressure sensor chip includes an encapsulation structure located on the second side; the encapsulation structure seals the pressure chamber.

3. The pressure sensor chip according to claim 1, characterized in that, The average ion concentration in the pressure-sensitive functional area is greater than or equal to 1*e^15 / cm^2 and less than or equal to 3*e^15 / cm^2.

4. The pressure sensor chip according to claim 1, characterized in that, A pressure cavity is provided on the second surface of the substrate. The pressure cavity is frustum-shaped, with the top or bottom of the frustum located on the side close to the varistor.

5. The pressure sensor chip according to claim 4, characterized in that, The varistor and the conductive plate are provided with an upper sealing cover on the side away from the substrate, and the upper sealing cover includes a first sealing cavity corresponding to the varistor.

6. The pressure sensor chip according to claim 5, characterized in that, The maximum distance between two of the plurality of varistors is less than the width of the pressure cavity on the side closest to the varistor, and the width of the pressure cavity on the side closest to the varistor is less than the width of the first sealing cavity.

7. The pressure sensor chip according to claim 1, characterized in that, The depth of the pressure-sensitive functional area is greater than or equal to 0.4 micrometers and less than or equal to 1.5 micrometers. The edge of the pressure-sensitive functional area gradually contracts inward from the first surface to the direction away from the first surface, with a contraction angle greater than or equal to 35° and less than or equal to 55°.

8. The pressure sensor chip according to claim 1, characterized in that, The substrate includes an isolation layer, and the pressure-sensitive functional area is formed on the side of the isolation layer near the first surface.

9. The pressure sensor chip according to claim 1, characterized in that, The sheet resistance of the pressure-sensing functional area of ​​the pressure sensor chip is greater than or equal to 45Ω / square and less than or equal to 55Ω / square; the junction depth of the pressure-sensing functional area of ​​the pressure sensor chip is greater than or equal to 0.4 micrometers and less than or equal to 1.5 micrometers; and the average concentration of the pressure-sensing functional area of ​​the pressure sensor chip is greater than or equal to 1*e^15 / cm^3 and less than or equal to 3*e^15 / cm^3.

10. A method for manufacturing a pressure sensor chip, characterized in that, include: Prepare a substrate, the substrate comprising a first surface and a second surface opposite to each other; A mask is coated on the first surface of the substrate; Pattern the mask on the first surface and form a barrier layer on the first surface; An implantation layer is formed on the first surface using an ion implantation process; The blocking layer is removed and the injection layer is etched to form a pressure-sensitive functional area, which includes a plurality of piezoresistors, a conductive plate and a void. A pressure cavity is formed on the second surface by etching; Manufacturing electrodes and packaging structures.

11. A pressure sensor, characterized in that, The pressure sensor includes the pressure sensor chip as described in any one of claims 1-9.

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