Membrane-based pressure sensor
By using a reverse coating process to form a MEMS piezoresistive pressure sensor, the problems of high processing difficulty and high cost of traditional silicon-based MEMS piezoresistive pressure sensors are solved, enabling simpler and lower-cost pressure sensor manufacturing and improving the stability and accuracy of electrical signal transmission.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- INTELLIMICRO MEDICAL CO LTD
- Filing Date
- 2025-09-02
- Publication Date
- 2026-08-04
AI Technical Summary
Traditional silicon-based MEMS piezoresistive pressure sensor chips are difficult to fabricate, ion implantation equipment is expensive and diffusion processes are difficult to control, and the alignment accuracy between the front piezoresistor and the back silicon cup is difficult to guarantee.
A MEMS piezoresistive pressure sensor is formed using a reverse coating process, comprising an insulating layer, a metal layer, a piezoresistive resistor, a piezoresistive film, and a support layer. A metal circuit is formed by forming a through hole in the insulating layer and filling it with the metal layer. The piezoresistive resistor contacts the metal circuit and covers the metal layer and the piezoresistive film. Finally, a cavity is set on the support layer and the sacrificial layer is removed to achieve separation.
The process is simplified, avoiding ion implantation and diffusion processes, reducing costs, and improving structural strength and the stability of electrical signal transmission.
Smart Images
Figure CN224590699U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor technology, and in particular to a MEMS piezoresistive pressure sensor. Background Technology
[0002] Silicon-based MEMS piezoresistive pressure sensors are widely used in automotive electronics, medical equipment, environmental monitoring, aerospace and other fields. They obtain pressure information by measuring the change in resistance of the piezoresistor when the silicon-based diaphragm is deformed under pressure.
[0003] Traditional silicon-based MEMS piezoresistive pressure sensor chips are mainly fabricated using two processes: The first involves forming a piezoresistor through ion implantation or diffusion on the front side, and then creating a silicon cup through deep silicon etching on the back side to fabricate the pressure-sensitive film. The second involves first fabricating the silicon cup through deep silicon etching, then creating the pressure-sensitive film through wafer bonding and thinning on the front side, and finally fabricating the piezoresistor through ion implantation or diffusion on the pressure-sensitive film. Both methods of fabricating silicon-based MEMS piezoresistive pressure sensor chips have the following drawbacks: First, both methods require ion implantation or diffusion to form the piezoresistor, but ion implantation equipment is expensive, and the uniformity of the diffusion process is difficult to control. Second, both methods involve alignment between the front piezoresistor and the back silicon cup, which is difficult to guarantee in terms of alignment accuracy and results in high processing difficulty. Utility Model Content
[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a MEMS piezoresistive pressure sensor that can be formed by reverse coating, which not only simplifies the processing but also avoids processes such as ion implantation and diffusion, resulting in lower costs.
[0005] A MEMS piezoresistive pressure sensor according to an embodiment of the present invention includes an insulating layer, a metal layer, a piezoresistive resistor, a piezoresistive film, and a support layer. The insulating layer has a through-hole extending along its thickness direction. The metal layer is disposed on the insulating layer and fills the through-hole. The metal layer has a metal circuit. The piezoresistive resistor is disposed on the insulating layer and contacts the metal circuit. The piezoresistive film is disposed on the insulating layer and covers the metal layer and the piezoresistive resistor. The support layer is disposed on the side of the piezoresistive film opposite to the insulating layer. The support layer has a cavity. The size of the through-hole is larger than the size of the piezoresistive resistor along the width direction and / or length direction of the insulating layer.
[0006] The MEMS piezoresistive pressure sensor according to the embodiments of this utility model has at least the following beneficial effects:
[0007] In fabricating a pressure sensor, a sacrificial layer can be formed on a substrate, followed by an insulating layer. Through-holes are formed in the insulating layer, and a metal layer filling the through-holes is then formed on the insulating layer. Metal circuitry is formed in the metal layer, and a piezoresistive resistor is formed on the insulating layer to contact the metal circuitry. A piezoresistive thin film covering the metal layer and the piezoresistive resistor is then formed on the insulating layer. A support layer is then formed on the side of the piezoresistive thin film facing away from the insulating layer, and a cavity is formed on the support layer. Finally, the sacrificial layer is removed using methods such as wet etching, separating the insulating layer from the substrate. Compared to traditional silicon-based MEMS piezoresistive pressure sensor chips, the MEMS piezoresistive pressure sensor of this embodiment can be fabricated using a reverse deposition method, which is not only simpler to process but also avoids processes such as ion implantation and diffusion, resulting in lower costs.
[0008] According to some embodiments of this utility model, the cross-sectional area of the through hole is 1000 μm. 2 Up to 1,000,000 μm 2 .
[0009] According to some embodiments of the present invention, the thickness of the insulating layer is 0.1 μm to 0.5 μm; and / or, the thickness of the varistor is 0.1 μm to 5 μm.
[0010] According to some embodiments of the present invention, the thickness of the pressure-sensitive film is 1 μm to 20 μm; and / or, the thickness of the support layer is 100 μm to 500 μm.
[0011] According to some embodiments of the present invention, the varistor is attached to the sidewall of the metal layer, the varistor has an extension portion, and the extension portion is attached to the surface of the metal layer opposite to the insulating layer.
[0012] According to some embodiments of the present invention, the cavity penetrates the support layer along the thickness direction.
[0013] According to some embodiments of the present invention, the projection along the thickness direction shows that at least a portion of the piezoresistor coincides with the cavity.
[0014] According to some embodiments of the present invention, the support layer is made of an oxide layer, a nitrided layer, or a metal.
[0015] According to some embodiments of the present invention, the insulating layer is an oxide layer, a nitrided layer, or a composite stack of an oxide layer and a nitrided layer.
[0016] According to some embodiments of this utility model, the pressure-sensitive film is made of an electrically insulating material.
[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and some advantages will become apparent from the description or may be learned by practice of the invention. Attached Figure Description
[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:
[0019] Figure 1 This is a schematic diagram of the structure of a MEMS piezoresistive pressure sensor according to an embodiment of the present invention;
[0020] Figure 2 This is a schematic diagram showing the process of manufacturing a pressure sensor without removing the substrate and sacrificial layer.
[0021] Icon labels:
[0022] Insulating layer 100; Through hole 101;
[0023] Metal layer 200;
[0024] Varistor 300; Extension 301;
[0025] Pressure-sensitive film 400;
[0026] Support layer 500; cavity 501;
[0027] Substrate 600;
[0028] Sacrifice layer 700. Detailed Implementation
[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.
[0030] The following is for reference. Figure 1 and Figure 2 This invention describes a MEMS piezoresistive pressure sensor according to an embodiment of the present invention.
[0031] refer to Figure 1 and Figure 2 As shown, the MEMS piezoresistive pressure sensor according to an embodiment of the present invention includes an insulating layer 100, a metal layer 200, a piezoresistive resistor 300, a piezoresistive film 400, and a support layer 500.
[0032] The insulating layer 100 has a through hole 101 extending through the thickness direction of the insulating layer 100. Specifically, a mask layer can be formed on the surface of the insulating layer 100, and the mask layer can be patterned using a photolithography process to form an opening for etching the through hole 101 in the mask layer. Then, the insulating layer 100 is etched through the opening of the mask layer to form the through hole 101 extending through the insulating layer 100 along the thickness direction of the insulating layer 100.
[0033] A metal layer 200 is disposed on the insulating layer 100 and fills the via 101, forming a metal circuit. For example, the metal layer 200 can be formed on the insulating layer 100 using PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) processes, filling the via 101. Simultaneously, the metal layer 200 is patterned using photolithography and etching processes to form a metal circuit on the metal layer 200. The metal circuit includes portions located on the insulating layer 100 and within the via 101, and the portions located on the insulating layer 100 and within the via 101 are connected together.
[0034] A varistor 300 is disposed on the insulating layer 100 and in contact with the metal circuit. For example, a resistive layer can be formed on the insulating layer 100 using PVD or CVD processes. A mask layer is formed on the surface of the resistive layer, and the mask layer is patterned using a photolithography process to form openings in the mask layer. Then, the resistive layer is etched through the openings in the mask layer to form the varistor 300. A portion of the varistor 300 may cover the metal layer 200, and a portion may cover the insulating layer 100, meaning that at least a portion of the varistor 300 is in contact with the metal circuit.
[0035] A pressure-sensitive film 400 is disposed on the insulating layer 100 and covers the metal layer 200 and the varistor 300. For example, the pressure-sensitive film 400 can be formed by epitaxy, PVD, or CVD processes, and the pressure-sensitive film 400 covers the insulating layer 100, the metal circuit, and the varistor 300. The pressure-sensitive film 400 can be made of materials with different elastic moduli depending on the application scenario and measurement range.
[0036] A support layer 500 is disposed on the side of the pressure-sensitive film 400 opposite to the insulating layer 100, and a cavity 501 is formed in the support layer 500. For example, the support layer 500 can be formed on the side of the pressure-sensitive film 400 opposite to the insulating layer 100 using PVD or CVD processes. Then, the cavity 501 is formed, for example, using photolithography and etching processes. The cavity 501 can penetrate the support layer 500 along its thickness direction, or it can not penetrate the support layer 500.
[0037] In this design, the size of the through-hole 101 is larger than the size of the varistor 300 along the width and / or length direction of the insulating layer 100. This larger size of the through-hole 101 results in a larger metal layer 200 filling the through-hole 101, leading to higher structural strength, less susceptibility to breakage, longer service life, easier connection to external circuits, and more stable and reliable power and signal transmission.
[0038] In this application, when fabricating a pressure sensor, a sacrificial layer 700 can be formed on a substrate 600, followed by an insulating layer 100 formed on the sacrificial layer 700. The insulating layer 100 has through holes 101 formed thereon. Then, a metal layer 200 filling the through holes 101 is formed on the insulating layer 100. Metal lines are formed on the metal layer 200, and a varistor 300 contacting the metal lines is formed on the insulating layer 100. Then, a varistor film 400 covering the metal layer 200 and the varistor 300 is formed on the insulating layer 100. Then, a support layer 500 is formed on the side of the varistor film 400 away from the insulating layer 100, and a cavity 501 is provided on the support layer 500. Finally, the sacrificial layer 700 is removed by wet etching or other methods, so that the insulating layer 100 is separated from the substrate 600.
[0039] Compared to traditional silicon-based MEMS piezoresistive pressure sensor chips, the MEMS piezoresistive pressure sensor according to the present invention can be formed by reverse coating, which is not only simpler to process, but also avoids processes such as ion implantation and diffusion, resulting in lower cost.
[0040] It should be noted that the thickness direction mentioned in this utility model refers to the thickness direction of the insulating layer 100.
[0041] In some embodiments of this utility model, the cross-sectional area of the through hole 101 is 1000 μm. 2 Up to 1,000,000 μm 2 For example, the cross-sectional area of through-hole 101 can be 1000 μm. 2 10000μm 2 100000μm 2 1,000,000 μm 2 Or other suitable sizes. In this way, not only can the size of the metal layer 200 filling the through hole 101 be avoided from being too small, which would affect the transmission of electrical power and signals, but the through hole 101 can also be avoided from being too large, which would affect the filling of the metal layer 200 and cause waste of the metal layer 200.
[0042] In some embodiments of this invention, the thickness of the insulating layer 100 is from 0.1 μm to 0.5 μm. For example, the thickness of the insulating layer 100 can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, or other suitable dimensions. This not only avoids the insulating layer 100 being too thin, which would affect the insulation effect, but also avoids the insulating layer 100 being too thick, which would lead to material waste and an excessively thick pressure sensor.
[0043] In some embodiments of this invention, the thickness of the varistor 300 is from 0.1 μm to 5 μm. For example, the thickness of the varistor 300 can be 0.1 μm, 1 μm, 2 μm, 4 μm, 5 μm, or other suitable dimensions. This avoids the varistor 300 being too thin or too thick, which would affect its varistor characteristics.
[0044] In some embodiments of this invention, the thickness of the pressure-sensitive film 400 is between 1 μm and 20 μm. For example, the thickness of the pressure-sensitive film 400 can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, or other suitable dimensions. This not only avoids the pressure-sensitive film 400 being too thin and affecting its electrical insulation effect, but also avoids the pressure-sensitive film 400 being too thick and affecting the pressure-sensitive resistor 300's sensitivity to pressure changes, as well as preventing the pressure sensor from becoming too thick.
[0045] In some embodiments of this invention, the thickness of the support layer 500 is between 100 μm and 500 μm. For example, the thickness of the support layer 500 can be 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, or other suitable dimensions. This not only avoids the support layer 500 being too thin, which would affect the molding effect and working performance of the cavity 501, but also avoids the support layer 500 being too thick, which would result in material waste and an excessively thick pressure sensor.
[0046] refer to Figure 1 and Figure 2 As shown, in some embodiments of this invention, the varistor 300 is attached to the sidewall of the metal layer 200, and the varistor 300 has an extension 301 that is attached to the surface of the metal layer 200 away from the insulating layer 100. In this embodiment, in addition to being attached to the sidewall of the metal layer 200, the varistor 300 also has an extension 301 that is attached to the surface of the metal layer 200 away from the insulating layer 100. This makes the contact between the varistor 300 and the metal lines of the metal layer 200 more comprehensive and tighter, resulting in better power transmission and signal transmission.
[0047] refer to Figure 1 and Figure 2As shown, in some embodiments of this utility model, the cavity 501 penetrates the support layer 500 along the thickness direction. For example, the cavity 501 may be located in the middle of the support layer 500.
[0048] In this embodiment, the cavity 501 penetrates the support layer 500 along the thickness direction, and thus the cavity 501 directly contacts the pressure-sensitive film 400. In this way, the structure formed by the cavity 501 can directly act on the pressure-sensitive film 400, thereby making the influence on the pressure-sensitive resistor 300 more direct and obvious, and thus making the pressure detection of the MEMS piezoresistive pressure sensor of this application more accurate.
[0049] refer to Figure 1 and Figure 2 As shown, in some embodiments of this utility model, the projection along the thickness direction shows that at least a portion of the varistor 300 coincides with the cavity 501.
[0050] In this embodiment, the structure formed by the cavity 501 has a more direct and obvious influence on the piezoresistive resistor 300, thereby making the pressure detection of the MEMS piezoresistive pressure sensor of this application more accurate.
[0051] In some embodiments of this invention, the insulating layer 100 may be an oxide layer, a nitride layer, or a composite layer of oxide and nitride. In one embodiment, the insulating layer 100 may be, for example, SiO2, SiNx, or other materials with good insulation, corrosion resistance, and wear resistance.
[0052] In some embodiments of this invention, the support layer 500 is made of an oxide layer, a nitride layer, or a metal. In one embodiment, the support layer 500 may be made of SiO2, SiNx, or a metal material with high hardness.
[0053] In some embodiments of this invention, the metal layer 200 can be made of materials with good electrical conductivity, such as copper, aluminum, gold, silver, or alloys. The metal layer 200 not only serves as a conductive channel but also as a bridge between the varistor 300 and the external circuit, ensuring effective transmission of electrical signals.
[0054] In some embodiments of this invention, the material of the varistor 300 can be, but is not limited to, metal oxides such as zinc oxide and barium oxide, or polymers and coatings with pressure-sensitive properties. The varistor 300 is a relatively common resistor structure, and its structure and working principle will not be described in detail here.
[0055] In some embodiments of this invention, the pressure-sensitive film 400 is made of an electrically insulating material. This prevents leakage. It should be noted that the pressure-sensitive film 400 can also be made of a high-resistivity material.
[0056] The manufacturing process of the MEMS piezoresistive pressure sensor described in this application is briefly explained below.
[0057] A sacrificial layer 700 is fabricated on the substrate 600 by means of spin coating or deposition. The sacrificial layer 700 can be selected from, but is not limited to, a thermosetting adhesive with good leveling properties and solubility in a specific solution, a metal or oxide that can be wet-etched, etc.
[0058] An insulating layer 100 is formed on the surface of the sacrificial layer 700 away from the substrate 600, and a through-hole 101 is formed on the insulating layer 100;
[0059] A metal layer 200 is formed on the surface of the insulating layer 100 away from the sacrificial layer 700. The metal layer 200 fills the via 101 and forms a metal circuit.
[0060] A varistor 300 is formed on the surface of the insulating layer 100 away from the sacrificial layer 700, and the varistor 300 contacts the metal circuit.
[0061] A pressure-sensitive film 400 is formed on the surface of the insulating layer 100 away from the sacrificial layer 700, and the pressure-sensitive film 400 covers the pressure-sensitive resistor 300 and the metal layer 200;
[0062] A support layer 500 is formed on the surface of the pressure-sensitive film 400 away from the sacrificial layer 700, and a cavity 501 is formed on the support layer 500;
[0063] Remove the sacrificial layer 700 to release the substrate 600.
[0064] In summary, the MEMS piezoresistive pressure sensor according to this embodiment of the invention, formed by reverse coating, is not only simple to manufacture and low in cost, but also possesses excellent pressure detection performance and stability. This pressure sensor can be widely used in aerospace, medical devices, automotive electronics, and other fields, providing reliable technical support for various pressure measurement needs.
[0065] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.
Claims
1. A MEMS piezoresistive pressure sensor, characterized in that, include: An insulating layer having through holes extending along the thickness direction of the insulating layer; A metal layer is disposed on the insulating layer and fills the through-hole, and the metal layer forms a metal circuit; A varistor is disposed on the insulating layer and in contact with the metal circuit; A pressure-sensitive film is disposed on the insulating layer and covers the metal layer and the pressure-sensitive resistor; A support layer is disposed on the side of the pressure-sensitive film opposite to the insulating layer, and the support layer has a cavity. Wherein, along the width and / or length direction of the insulating layer, the size of the through hole is larger than the size of the varistor.
2. The MEMS piezoresistive pressure sensor according to claim 1, characterized in that, The cross-sectional area of the through hole is 1000 μm. 2 Up to 1,000,000 μm 2 .
3. The MEMS piezoresistive pressure sensor according to claim 1, characterized in that, The thickness of the insulating layer is from 0.1 μm to 0.5 μm; and / or, The thickness of the varistor is from 0.1 μm to 5 μm.
4. The MEMS piezoresistive pressure sensor according to claim 1, characterized in that, The thickness of the pressure-sensitive film is from 1 μm to 20 μm; and / or, The thickness of the support layer is between 100 μm and 500 μm.
5. The MEMS piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, The varistor is attached to the sidewall of the metal layer, and the varistor has an extension portion that is attached to the surface of the metal layer opposite to the insulating layer.
6. The MEMS piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, The cavity penetrates the support layer along the thickness direction.
7. The MEMS piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, The projection along the thickness direction shows that at least a portion of the piezoresistor coincides with the cavity.
8. The MEMS piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, The support layer is made of an oxide layer, a nitrided layer, or a metal.
9. The MEMS piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, The insulating layer is an oxide layer, a nitrided layer, or a composite stack of an oxide layer and a nitrided layer.
10. The MEMS piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, The pressure-sensitive film is made of an electrically insulating material.