MEMS device and preparation method thereof

Abstract

The invention relates to the technical field of semiconductors, and discloses an MEMS device and a preparation method thereof, and the MEMS device comprises a substrate structure layer and a movable structure layer which are stacked from bottom to top; the substrate structure layer comprises a substrate layer and an interconnection layer above the substrate layer; the movable structure layer comprises a moving part and a cantilever beam at the side part of the moving part; the movable structure layer comprises a silicon carbide layer and a diamond-like carbon film layer which are stacked from bottom to top; wherein the silicon carbide layer is relatively close to the substrate structure layer. According to the invention, the anti-vibration inertia stress capability of the moving part and the cantilever beam can be improved, the mechanical stability, the manufacturing yield and the use reliability of the device can be improved, meanwhile, the heat diffusion can be accelerated, and the influence of temperature rise on the working stability can be reduced, thereby improving the working stability and precision of the device.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a MEMS device and its fabrication method. Background Technology

[0002] In the manufacturing and use of MEMS devices, especially accelerometers, fracture failure of moving parts and cantilever beams is one of the common failure modes. This is because the material of conventional moving parts and cantilever beams is silicon, which has low hardness. This results in poor resistance to vibration and inertial stress in the moving structural layer, as well as poor mechanical stability of the device, thus reducing the manufacturing yield and reliability of MEMS devices. Meanwhile, temperature drift is another common problem affecting the operational stability of MEMS devices. Due to the low thermal conductivity of silicon, heat dissipation is not timely during device operation, leading to slow heat diffusion in the moving structural layer, causing localized temperature rises, which in turn reduces operational stability and device accuracy.

[0003] Therefore, a solution is needed that can enhance the energy of the moving parts and cantilever beam to resist vibration inertial stress, thereby improving the mechanical stability and reliability of the device, while reducing the impact of temperature drift on the device's operational stability. Summary of the Invention

[0004] This invention provides a MEMS device and its fabrication method to solve the problems in related technologies, such as the low hardness of the movable structural layer leading to the fracture failure of moving parts and cantilever beams, and the low thermal conductivity of the movable structural layer leading to low device stability and accuracy.

[0005] In a first aspect, the present invention provides a MEMS device, comprising: The base structure layer and the movable structure layer are stacked from bottom to top; The substrate structure layer includes the substrate layer and the interconnect layer above it; The movable structural layer includes moving parts and cantilever beams on its sides; The movable structural layer comprises a silicon carbide layer and a diamond-like carbon film layer stacked from bottom to top; wherein the silicon carbide layer is relatively close to the substrate structural layer.

[0006] The MEMS device provided by this invention designs the movable structural layer, which includes moving parts and a cantilever beam, as a composite structure layer of silicon carbide and diamond-like carbon film. Firstly, since the hardness of silicon carbide and diamond-like carbon film is much greater than that of silicon, this structure can significantly improve the resistance to vibration inertial stress of the moving parts and cantilever beam, enhancing the mechanical stability of the device and simultaneously improving manufacturing yield and reliability. Secondly, because silicon carbide and diamond-like carbon film have high thermal conductivity, they can accelerate heat dissipation, reducing the impact of temperature rise on operational stability, thereby improving the operational stability and accuracy of the device. Thirdly, the diamond-like carbon film deposited on the upper surface of the silicon carbide material helps improve the etching morphology at the silicon carbide surface; therefore, a composite material of silicon carbide and diamond-like carbon film is chosen. Fourthly, during the etching of the silicon carbide layer, the carbon film can act as a mask, helping to shield photoresist pinhole defects and improve process yield; therefore, the diamond-like carbon film layer is placed above the silicon carbide layer.

[0007] In one alternative implementation, the substrate layer is made of silicon; The thickness of the diamond-like carbon film is 30nm~100nm; The thickness of the silicon carbide layer is 10µm~50µm.

[0008] The MEMS device provided by this invention has a silicon carbide layer with a thickness of 10µm to 50µm, which can ensure that moving parts and cantilever beams have high resistance to vibration inertial stress, thereby further improving the mechanical stability, manufacturing yield and reliability of the device; the diamond-like carbon film layer has a thickness of 30nm to 100nm, which can effectively accelerate heat dissipation and further reduce the impact of temperature rise on working stability.

[0009] In one alternative implementation, the MEMS device is an accelerometer; the movable structure layer also includes a mass block located on the side of the cantilever beam; one end of the cantilever beam is connected to the mass block, and the other end is connected to the moving part; A first groove is provided on the upper surface of the base structure layer; The moving part and the cantilever beam are located above the corresponding position of the first groove; the moving part and the cantilever beam are adapted to move within the first groove.

[0010] In one alternative embodiment, the MEMS device further includes: a packaging wafer located above the substrate structure layer, including a top cover and sidewall covers; the packaging wafer also surrounds the movable structure layer and forms a vacuum cavity; A second groove is provided on the upper surface of the base structure layer; the side wall cover is located in the second groove; the lower part of the side wall cover is connected to the bottom of the second groove through a metal bonding layer.

[0011] In one alternative embodiment, the interconnect layer includes a conductive interconnect structure and a dielectric layer; the dielectric layer is located on the upper surface of the substrate layer; the conductive interconnect structure is located inside the dielectric layer. The dielectric layer is made of silicon dioxide; the conductive interconnect structure is made of a conductive metal. A bonding layer is also provided on the lower surface of the silicon carbide layer; The silicon carbide layer and the substrate structure layer are bonded together through a bonding layer and a dielectric layer; The bonding layer is made of silicon dioxide; the thickness of the bonding layer is 20nm~500nm.

[0012] The MEMS device provided by this invention has a silicon carbide layer and a substrate structure layer bonded together by a bonding layer and a dielectric layer, which can improve the bonding between the silicon carbide layer and the substrate structure layer, thereby improving the reliability of the device.

[0013] Secondly, the present invention provides a method for fabricating a MEMS device, comprising: A substrate structure layer is formed; the substrate structure layer includes the substrate layer and the interconnect layer above it; A movable structural layer is formed on the upper surface of the substrate structural layer; the movable structural layer includes a moving component and a cantilever beam on its side; the movable structural layer includes a silicon carbide layer and a diamond-like carbon film layer stacked from bottom to top; the silicon carbide layer is relatively close to the substrate structural layer.

[0014] In one alternative implementation, the step of forming the substrate structure layer includes: Provide the first silicon wafer; Ion implantation is performed on the surface of the first silicon wafer, and a dielectric layer is deposited thereon. Photolithography and metal deposition processes are performed on the surface of the first silicon wafer to form a conductive interconnect structure inside the dielectric layer. The remaining first silicon wafer serves as the base layer, and the dielectric layer and the conductive interconnect structure inside it constitute the interconnect layer. Following the step of forming the movable structural layer, the following steps are also included: Provides a packaging wafer, which includes a top cover and sidewall covers; The packaging wafer is bonded to the top of the substrate structure layer. The packaging wafer and the substrate structure layer form a vacuum cavity, and the movable structure layer is located in the vacuum cavity.

[0015] In one alternative implementation, the step of forming the movable structural layer includes: A silicon carbide layer is formed on the upper surface of the substrate structure layer; A diamond-like carbon film layer is formed on the side surface of the silicon carbide layer facing away from the substrate structure layer by using plasma-assisted chemical vapor deposition or sputtering process. Photolithography and etching are performed on the stacked silicon carbide and diamond-like carbon film layers to form a movable structure layer; the movable structure layer includes moving parts and cantilever beams on its sides.

[0016] In one alternative embodiment, the step of forming a silicon carbide layer on the upper surface of the substrate structure layer includes: Provide initial silicon carbide wafers; A bonding layer is formed on the surface of the initial silicon carbide wafer; The bonding layer is bonded to the upper surface of the substrate structure layer on the side facing away from the initial silicon carbide wafer. The initial silicon carbide wafer is thinned to obtain a silicon carbide layer.

[0017] The method for fabricating MEMS devices provided by this invention first forms a bonding layer on the surface of an initial silicon carbide wafer, bonds it to the upper surface of a substrate structure layer, and then thins the initial silicon carbide wafer to form a stacked bonding layer and silicon carbide layer on the upper surface of the substrate structure layer. On the one hand, only one wafer bonding is required, which simplifies the process flow, and the bonding layer can improve the adhesion between the silicon carbide layer and the substrate structure layer. On the other hand, forming the silicon carbide layer by thinning the initial silicon carbide wafer allows for better control of the surface roughness and uniformity of the silicon carbide layer, thereby improving the uniformity of the subsequently formed diamond-like carbon film layer and the adhesion between the diamond-like carbon film layer and the silicon carbide layer, thus enhancing the mechanical stability and reliability of the movable structure layer.

[0018] In one alternative embodiment, the step of forming a silicon carbide layer on the upper surface of the substrate structure layer includes: Provide a second silicon wafer; deposit a silicon carbide layer on the surface of the second silicon wafer; A bonding layer is formed on the side of the silicon carbide layer facing away from the second silicon wafer; The bonding layer is bonded to the upper surface of the substrate structure layer on the side opposite to the silicon carbide layer, and the second silicon wafer is removed.

[0019] The method for fabricating MEMS devices provided by this invention involves first forming a silicon carbide layer and a bonding layer on the surface of a second silicon wafer, bonding them to the upper surface of a substrate structure layer, and then removing the second silicon wafer, thereby forming a stacked bonding layer and silicon carbide layer on the upper surface of the substrate structure layer. On the one hand, forming the silicon carbide layer on the surface of the second silicon wafer first allows for precise control of the deposition thickness of the silicon carbide layer, thereby precisely controlling the thickness of the movable structure layer and improving the fabrication yield. On the other hand, using the bonding layer to achieve the bonding between the silicon carbide layer and the substrate structure layer can improve the bonding between the silicon carbide layer and the substrate structure layer. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of a MEMS device according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 3 This is a schematic flowchart of a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a first silicon wafer provided in a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the substrate layer formed in a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of forming a silicon carbide layer in a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a diamond-like carbon film layer formed in a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure forming a movable structural layer in a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the bonding and packaging wafer structure in a method for fabricating a MEMS device according to an embodiment of the present invention; Figure 10A This is a schematic diagram of the initial silicon carbide wafer provided in Example 1; Figure 10B This is a schematic diagram of the structure in Example 1 where a bonding layer is formed on the surface of an initial silicon carbide wafer; Figure 10C This is a schematic diagram of the structure in Example 1 where the initial silicon carbide wafer is bonded to the upper surface of the substrate structure layer; Figure 10D This is a schematic diagram of the structure in Example 1 that forms a silicon carbide layer; Figure 11A This is a schematic diagram of the structure in Example 2 where a silicon carbide layer is deposited on the surface of the second silicon wafer; Figure 11B This is a schematic diagram of the structure forming the bonding layer in Example 2; Figure 11C This is a schematic diagram of the structure in Example 2 where the silicon carbide layer is bonded to the upper surface of the substrate structure layer; Figure 11D This is a schematic diagram of the structure in Example 2 where the second silicon wafer has been removed.

[0022] Figure label: 10. Substrate structure layer; 11. Substrate layer; 12. Interconnect layer; 121. Dielectric layer; 122. Conductive interconnect structure; 20. Movable structure layer; 201. Moving part; 202. Cantilever beam; 203. Mass block; 21. Silicon carbide layer; 22. Diamond-like carbon film layer; 23. Bonding layer; 30. Encapsulation wafer; 31. Metal bonding layer; 110. First silicon wafer; 210. Initial silicon carbide wafer; 60. Second silicon wafer; 41. First groove; 42. Second groove; 50. Electrode structure. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention and not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] In the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present invention. Various structural schematic diagrams according to embodiments of the present invention are shown in the accompanying drawings. These drawings are not to scale, and some details are enlarged for clarity, and some details may be omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed. In the context of the present invention, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "on" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0025] In the manufacturing and use of MEMS devices, especially accelerometers, fracture failure of moving parts and cantilever beams is one of the common failure modes. This is because the material of conventional moving parts and cantilever beams is silicon, which has low hardness. This results in poor resistance to vibration and inertial stress in the moving structural layer, as well as poor mechanical stability of the device, thus reducing the manufacturing yield and reliability of MEMS devices. Meanwhile, temperature drift is another common problem affecting the operational stability of MEMS devices. Due to the low thermal conductivity of silicon, heat dissipation is not timely during device operation, leading to slow heat diffusion in the moving structural layer, causing localized temperature rises, which in turn reduces operational stability and device accuracy.

[0026] Therefore, a solution is needed that can enhance the energy of the moving parts and cantilever beam to resist vibration inertial stress, thereby improving the mechanical stability and reliability of the device, while reducing the impact of temperature drift on the device's operational stability.

[0027] like Figure 1 As shown, this embodiment provides a MEMS device, including: The base structure layer 10 and the movable structure layer 20 are stacked from bottom to top; The substrate structure layer 10 includes a substrate layer 11 and an interconnect layer 12 above it; The movable structural layer 20 includes a moving component 201 and a cantilever beam 202 on its side; The movable structural layer 20 includes a silicon carbide layer 21 and a diamond-like carbon film layer 22 stacked from bottom to top; wherein the silicon carbide layer 21 is relatively close to the substrate structural layer 10.

[0028] In specific implementation, the moving parts 201 and cantilever beam 202 in the movable structural layer 20 are both composite film layers including silicon carbide layer 21 and diamond-like carbon film layer 22.

[0029] The movable structural layer 20 includes a silicon carbide layer 21 and a diamond-like carbon film layer 22 stacked from bottom to top. On the one hand, depositing the diamond-like carbon film on the upper surface of the silicon carbide material helps to improve the etching morphology at the silicon carbide surface; on the other hand, in the process of etching to form the movable structural layer, the diamond-like carbon film can play a certain masking role on the silicon carbide layer during the etching of the composite film layer, which helps to avoid the formation of photoresist pinhole defects in the silicon carbide layer and improve the process yield.

[0030] The MEMS device provided in this embodiment designs the movable structural layer, which includes moving parts and a cantilever beam, as a composite structure layer of silicon carbide and diamond-like carbon film. Firstly, since the hardness of silicon carbide and diamond-like carbon film is much greater than that of silicon, this structure can significantly improve the resistance to vibration inertial stress of the moving parts and cantilever beam, enhancing the mechanical stability of the device and improving its manufacturing yield and reliability. Secondly, because silicon carbide and diamond-like carbon film have high thermal conductivity, they can accelerate heat dissipation, reducing the impact of temperature rise on operational stability, thereby improving the device's operational stability and accuracy. Thirdly, the diamond-like carbon film deposited on the upper surface of the silicon carbide material helps improve the etching morphology at the silicon carbide surface; therefore, a composite material of silicon carbide and diamond-like carbon film is chosen. Fourthly, during the etching of the silicon carbide layer, the carbon film can act as a mask, helping to shield photoresist pinhole defects and improve process yield; therefore, the diamond-like carbon film layer is placed above the silicon carbide layer.

[0031] Furthermore, the silicon carbide layer and the diamond-like carbon film layer have high bonding strength, which can form an integral composite structure layer, further improving the mechanical stability and reliability of the movable structure layer.

[0032] In some alternative embodiments, the thickness of the silicon carbide layer 21 is greater than the thickness of the diamond-like carbon film layer 22.

[0033] In practice, since the hardness of silicon carbide layer 21 is greater than that of diamond-like carbon film layer 22, silicon carbide layer 21 is used as the main structural layer of movable structural layer 20. That is, the thickness of silicon carbide layer 21 is greater than that of diamond-like carbon film layer 22, which can provide higher hardness and resistance to vibration inertial stress, thereby improving the mechanical stability of moving part 201 and cantilever beam 202.

[0034] The thermal conductivity of the diamond-like carbon film layer 22 is higher than that of the silicon carbide layer 21. Therefore, placing the diamond-like carbon film layer 22 on the upper surface of the movable structure layer 20 mainly improves heat dissipation performance and can effectively reduce the impact of temperature rise on the operating stability of the device. At the same time, when etching the silicon carbide layer, the diamond-like carbon film layer can play a masking role, which is beneficial to shielding photoresist pinhole defects and improving process yield.

[0035] In some alternative implementations, the material of the substrate 11 comprises silicon.

[0036] In some alternative embodiments, the thickness of the diamond-like carbon film 22 is 30 nm to 100 nm; The thickness of the silicon carbide layer 21 is 10µm~50µm.

[0037] The MEMS device provided in this embodiment has a silicon carbide layer with a thickness of 10µm to 50µm, which can ensure that the moving parts and cantilever beams have a high resistance to vibration inertial stress, thereby further improving the mechanical stability, manufacturing yield and reliability of the device; the diamond-like carbon film layer has a thickness of 30nm to 100nm, which can effectively accelerate heat dissipation and further reduce the impact of temperature rise on working stability.

[0038] In some alternative implementations, the MEMS device is an accelerometer; the movable structure layer 20 also includes a mass block 203 located on the side of the cantilever beam 202; one end of the cantilever beam 202 is connected to the mass block 203, and the other end is connected to the moving part 201; A first groove 41 is provided on the upper surface of the base structure layer 10; The moving part 201 and the cantilever beam 202 are located above the corresponding positions of the first groove 41; the moving part 201 and the cantilever beam 202 are adapted to move within the first groove 41.

[0039] In some alternative embodiments, the interconnect layer 12 includes a conductive interconnect structure 122 and a dielectric layer 121; the dielectric layer 121 is located on the upper surface of the substrate layer 11; the conductive interconnect structure 122 is located inside the dielectric layer 121. The dielectric layer 121 is made of silicon dioxide; the conductive interconnect structure 122 is made of a conductive metal.

[0040] In specific implementation, the dielectric layer 121 is made of silicon dioxide, and its thickness is set according to actual needs; this embodiment does not limit this. The conductive interconnect structure 122 is made of a conductive metal, such as titanium, titanium nitride, tungsten, aluminum copper, or a combination of titanium, tantalum, tungsten, aluminum copper, or other metals.

[0041] In some alternative embodiments, a bonding layer 23 is further disposed on the lower surface of the silicon carbide layer 21; The silicon carbide layer 21 and the substrate structure layer 10 are bonded together by the bonding layer 23 and the dielectric layer 121; The bonding layer 23 is made of silicon dioxide; the thickness of the bonding layer 23 is 20nm~500nm.

[0042] The MEMS device provided in this embodiment connects the silicon carbide layer and the substrate structure layer through a bonding layer and a dielectric layer, which can improve the bonding between the silicon carbide layer and the substrate structure layer, thereby improving the reliability of the device.

[0043] In some alternative implementations, the MEMS device further includes: a packaged wafer 30 located above the substrate structure layer 10, including an upper cover plate and sidewall covers plate; the packaged wafer 30 also surrounds the movable structure layer 20 and forms a vacuum cavity; A second groove 42 is provided on the upper surface of the base structure layer 10; a side wall cover plate is located in the second groove 42; the lower part of the side wall cover plate is connected to the bottom of the second groove 42 through a metal bonding layer 31.

[0044] In some alternative embodiments, the second groove 42 penetrates a portion of the dielectric layer 121 and exposes a portion of the conductive interconnect structure 122; the conductive interconnect structure 122 is made of a conductive metal. A metal bonding layer 31 is provided below the side wall cover plate; the metal bonding layer 31 and the conductive interconnect structure 122 are connected together by metal bonding.

[0045] In some alternative embodiments, the conductive interconnect structure 122 is made of titanium, titanium nitride, tungsten, aluminum copper, or a combination of titanium, tantalum, tungsten, aluminum copper, or other metals; the metal bonding layer 31 is made of germanium, aluminum copper, or a combination of germanium, gold, or other metals.

[0046] In some alternative implementations, the MEMS device further includes an electrode structure 50 located above the interconnect layer 12 and electrically connected to a portion of the conductive interconnect structure 122.

[0047] In some alternative implementations, the electrode structure 50 extends through the movable structure layer 20 and is connected to the underlying interconnect layer 12.

[0048] like Figure 2 As shown, this embodiment provides a method for fabricating a MEMS device, which includes, but is not limited to, steps S101 to S102.

[0049] Step S101: Forming a substrate structure layer 10; the substrate structure layer 10 includes a substrate layer 11 and an interconnect layer 12 above it, such as... Figure 5 As shown.

[0050] Step S102: A movable structural layer 20 is formed on the upper surface of the substrate structural layer 10; the movable structural layer 20 includes a moving component 201 and a cantilever beam 202 on its side; the movable structural layer 20 includes a silicon carbide layer 21 and a diamond-like carbon film layer 22 stacked from bottom to top; the silicon carbide layer 21 is relatively close to the substrate structural layer 10, such as... Figure 9 As shown.

[0051] In some alternative embodiments, the step of forming the substrate structure layer 10 includes: Provide the first silicon wafer 110, such as Figure 4 As shown; Ion implantation is performed on the surface of the first silicon wafer 110, and a dielectric layer 121 is deposited to form it, such as... Figure 5 As shown; Photolithography and metal deposition processes are performed on the upper surface of the first silicon wafer 110 to form a conductive interconnect structure 122 inside the dielectric layer 121. The remaining second silicon wafer 60 serves as the base layer 11. The dielectric layer 121 and the conductive interconnect structure 122 within it constitute the interconnect layer 12. Figure 5 As shown.

[0052] In some alternative implementations, after the step of forming the movable structural layer 20, the method further includes: A packaged wafer 30 is provided, the packaged wafer 30 including a top cover and a side wall cover; The packaging wafer 30 is bonded to the top of the substrate structure layer 10. The packaging wafer 30 and the substrate structure layer 10 constitute a vacuum cavity, and the movable structure layer 20 is located in the vacuum cavity. Figure 9 As shown.

[0053] In some alternative implementations, the step of forming the movable structural layer 20 includes: A silicon carbide layer 21 is formed on the upper surface of the substrate structure layer 10, such as Figure 6 As shown; A diamond-like carbon film 22 is formed on the side of the silicon carbide layer 21 facing away from the substrate structure layer 10 using plasma-assisted chemical vapor deposition or sputtering processes. Figure 7 As shown; Photolithography and etching are performed on the stacked silicon carbide layer 21 and diamond-like carbon film layer 22 to form a movable structure layer 20; the movable structure layer 20 includes a moving component 201 and a cantilever beam 202 on its side, such as... Figure 8 As shown.

[0054] In practice, the stacked silicon carbide layer 21 and diamond-like carbon film layer 22 are simultaneously photolithographically etched. Each part forming the movable structure layer 20 includes a composite film layer of silicon carbide layer 21 and diamond-like carbon film layer 22.

[0055] In some alternative embodiments, the step of forming a silicon carbide layer 21 on the upper surface of the substrate structure layer 10 includes: forming a stacked bonding layer 23 and a silicon carbide layer 21 on the upper surface of the substrate structure layer 10, such as... Figure 6 As shown; After the step of forming the diamond-like carbon film layer 22: the stacked bonding layer 23, silicon carbide layer 21 and diamond-like carbon film layer 22 are photolithographically and etched to form a movable structure layer 20; the movable structure layer 20 includes a moving part 201 and a cantilever beam 202 on its side.

[0056] In some alternative embodiments, the step of forming a silicon carbide layer 21 on the upper surface of the substrate structure layer 10 includes: Provide initial silicon carbide wafer 210, such as Figure 10A As shown; A bonding layer 23 is formed on the surface of the initial silicon carbide wafer 210, such as Figure 10B As shown; The bonding layer 23 is bonded to the upper surface of the substrate structure layer 10 on the side facing away from the initial silicon carbide wafer 210, such as... Figure 10C As shown; Thinning the initial silicon carbide wafer 210 yields a silicon carbide layer 21, as follows: Figure 10D As shown.

[0057] In practice, a chemical mechanical polishing process is used to thin the initial silicon carbide wafer 210, and the remaining initial silicon carbide wafer 210 becomes a silicon carbide layer 21, thereby forming a stacked bonding layer 23 and a silicon carbide layer 21 on the upper surface of the substrate structure layer 10.

[0058] The MEMS device fabrication method provided in this embodiment first forms a bonding layer on the surface of an initial silicon carbide wafer, bonds it to the upper surface of a substrate structure layer, and then thins the initial silicon carbide wafer to form a stacked bonding layer and silicon carbide layer on the upper surface of the substrate structure layer. On the one hand, only one wafer bonding is required, which simplifies the process flow, and the bonding layer can improve the adhesion between the silicon carbide layer and the substrate structure layer. On the other hand, forming the silicon carbide layer by thinning the initial silicon carbide wafer can better control the surface roughness and uniformity of the silicon carbide layer, thereby improving the uniformity of the subsequently formed diamond-like carbon film layer and the adhesion between the diamond-like carbon film layer and the silicon carbide layer, thus improving the mechanical stability and reliability of the movable structure layer.

[0059] In some alternative embodiments, the step of forming a silicon carbide layer 21 on the upper surface of the substrate structure layer 10 includes: A second silicon wafer 60 is provided; a silicon carbide layer 21 is deposited on the surface of the second silicon wafer 60, such as... Figure 11A As shown; A bonding layer 23 is formed on the surface of the silicon carbide layer 21 on the side facing away from the second silicon wafer 60, such as... Figure 11B As shown; The bonding layer 23 is bonded to the upper surface of the substrate structure layer 10 on the side opposite to the silicon carbide layer 21, such as... Figure 11C As shown, the second silicon wafer 60 is removed, as... Figure 11D As shown.

[0060] In practice, the second silicon wafer 60 is removed by etching or thinning and polishing, thereby forming a stacked bonding layer 23 and a silicon carbide layer 21 on the upper surface of the substrate structure layer 10.

[0061] The MEMS device fabrication method provided in this embodiment first forms a silicon carbide layer and a bonding layer on the surface of a second silicon wafer, bonds them to the upper surface of a substrate structure layer, and then removes the second silicon wafer, thereby forming a stacked bonding layer and silicon carbide layer on the upper surface of the substrate structure layer. On the one hand, forming a silicon carbide layer on the surface of the second silicon wafer first allows for precise control of the deposition thickness of the silicon carbide layer, thereby precisely controlling the thickness of the movable structure layer and improving the fabrication yield. On the other hand, using the bonding layer to achieve the bonding between the silicon carbide layer and the substrate structure layer can improve the bonding between the silicon carbide layer and the substrate structure layer.

[0062] In some alternative embodiments, after the step of forming the movable structural layer 20, the movable structural layer 20 is further further subjected to lubricant filling and surface treatment.

[0063] In some alternative embodiments, the step of forming the substrate structure layer 10 further includes: A first groove 41 is formed on the upper surface of the substrate structure layer 10; In the subsequent step of forming the movable structural layer 20, the moving part 201 and the cantilever beam 202 are located above the corresponding positions of the first groove 41; the moving part 201 and the cantilever beam 202 are adapted to move within the first groove 41.

[0064] In some alternative embodiments, the step of forming the substrate structure layer 10 further includes: A second groove 42 is formed on the upper surface of the base structure layer 10; In the subsequent step of bonding the packaged wafer 30 to the substrate structure layer 10, the sidewall cover is located in the second groove 42.

[0065] In some alternative embodiments, the second groove 42 penetrates a portion of the dielectric layer 121 and exposes a portion of the conductive interconnect structure 122; the conductive interconnect structure 122 is made of a conductive metal. The step of bonding the packaged wafer 30 to the substrate structure layer 10 further includes: forming a metal bonding layer 31 under the sidewall cover plate; The metal bonding layer 31 below the side wall cover plate is connected to the conductive interconnect structure 122 at the bottom of the second groove 42 by metal bonding.

[0066] like Figure 3 As shown, the present invention also provides a specific flowchart of a method for fabricating a MEMS device, including but not limited to steps S201 to S209.

[0067] Step S201, provide a first silicon wafer 110, such as Figure 4 As shown.

[0068] In step S202, ion implantation is performed on the surface of the first silicon wafer 110, and a dielectric layer 121 is deposited to form it. Figure 5 As shown.

[0069] In a specific implementation, the material of the dielectric layer 121 is silicon dioxide; the thickness of the dielectric layer 121 is set according to actual needs, and this embodiment does not limit it.

[0070] In step S203, photolithography and metal deposition processes are performed on the upper surface of the first silicon wafer 110 to form a conductive interconnect structure 122 inside the dielectric layer 121. The remaining second silicon wafer 60 serves as the base layer 11. The dielectric layer 121 and the conductive interconnect structure 122 inside it constitute the interconnect layer 12. The base layer 11 and the interconnect layer 12 above it constitute the base structure layer 10, as shown below. Figure 5 As shown.

[0071] In a specific implementation, the conductive interconnect structure 122 is made of a conductive metal, such as titanium, titanium nitride, tungsten, aluminum copper, or a combination of titanium, tantalum, tungsten, aluminum copper, or other metals. Part of the conductive interconnect structure 122 connects to the bottom first silicon wafer 110; the partial conductive interconnect structure 122 is used to connect the subsequent electrode structure 50 and the metal bonding layer 31.

[0072] In some examples, during the step of forming the conductive interconnect structure 122, a first groove 41 and a second groove 42 are also formed on the upper surface of the substrate structure layer 10.

[0073] Step S204: A layered bonding layer 23 and a silicon carbide layer 21 are formed on the upper surface of the substrate structure layer 10, such as... Figure 6 As shown.

[0074] In step S205, a diamond-like carbon film layer 22 is formed on the side of the silicon carbide layer 21 facing away from the substrate structure layer 10 using plasma-assisted chemical vapor deposition or sputtering. Figure 7 As shown.

[0075] Step S206 involves photolithography and etching of the stacked bonding layer 23, silicon carbide layer 21, and diamond-like carbon film layer 22 to form a movable structure layer 20; the movable structure layer 20 includes a moving component 201 and a cantilever beam 202 on its side, such as... Figure 8 As shown.

[0076] In practice, the stacked bonding layer 23, silicon carbide layer 21 and diamond-like carbon film layer 22 are simultaneously photolithographically etched; each part forming the movable structure layer 20 includes a composite film layer of bonding layer 23, silicon carbide layer 21 and diamond-like carbon film layer 22.

[0077] In some examples, the moving parts 201 and cantilever beam 202 in the movable structural layer 20 are located above the corresponding positions of the first groove 41; the moving parts 201 and cantilever beam 202 are adapted to move within the first groove 41.

[0078] Step S207: Lubricating oil is filled and surface treatment is performed on the movable structural layer 20.

[0079] Step S208: Provide a packaging wafer 30, which includes an upper cover and a side wall cover.

[0080] Step S209: The packaging wafer 30 is bonded to the top of the substrate structure layer 10. The packaging wafer 30 and the substrate structure layer 10 constitute a vacuum cavity, and the movable structure layer 20 is located in the vacuum cavity. Figure 9 As shown.

[0081] In practice, the side wall cover is located within the second groove 42.

[0082] In some examples, a metal bonding layer 31 is first formed under the sidewall cover, and then the metal bonding layer 31 under the sidewall cover is connected to the conductive interconnect structure 122 at the bottom of the second groove 42 by metal bonding.

[0083] In some alternative implementations, step S204 may involve forming a stacked bonding layer 23 and a silicon carbide layer 21 on the upper surface of the substrate structure layer 10 in various ways.

[0084] In Example 1, step S204 includes: S11, Provide initial silicon carbide wafer 210, such as Figure 10A As shown; S12. A bonding layer 23 is formed on the surface of the initial silicon carbide wafer 210, such as... Figure 10B As shown; S13. Bond the bonding layer 23 to the upper surface of the substrate structure layer 10 on the side facing away from the initial silicon carbide wafer 210, such as... Figure 10C As shown; S14. The initial silicon carbide wafer 210 is thinned using a chemical mechanical polishing process, leaving a silicon carbide layer 21 on the remaining initial silicon carbide wafer 210. This forms a stacked bonding layer 23 and silicon carbide layer 21 on the upper surface of the substrate structure layer 10. Figure 10D As shown.

[0085] In Example 2, step S204 includes: S21, Provide a second silicon wafer 60; Deposit a silicon carbide layer 21 on the surface of the second silicon wafer 60, such as Figure 11A As shown; S22. A bonding layer 23 is formed on the surface of the silicon carbide layer 21 on the side facing away from the second silicon wafer 60, such as... Figure 11B As shown; S23, Bond the side of bonding layer 23 away from silicon carbide layer 21 to the upper surface of substrate structure layer 10; as shown Figure 11C As shown; S24. The second silicon wafer 60 is removed by etching or thinning and polishing, thereby forming a stacked bonding layer 23 and a silicon carbide layer 21 on the upper surface of the substrate structure layer 10, such as... Figure 11D As shown.

[0086] In the description of this specification, the references to terms such as "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0087] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0088] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the appended claims.

Claims

1. A MEMS device, characterized by, Comprise: a substrate structure layer and a movable structure layer stacked from bottom to top; the substrate structure layer comprises a substrate layer and an interconnection layer above the substrate layer; the movable structure layer comprises a moving component and a cantilever beam at the side of the moving component; the movable structure layer comprises a silicon carbide layer and a diamond-like carbon film layer stacked from bottom to top; wherein the silicon carbide layer is relatively close to the substrate structure layer.

2. The MEMS device according to claim 1, wherein: the material of the substrate layer comprises silicon; the thickness of the diamond-like carbon film layer is 30nm-100nm; the thickness of the silicon carbide layer is 10µm-50µm.

3. The MEMS device according to claim 1, wherein: the MEMS device is an accelerometer; the movable structure layer further comprises a mass block at the side of the cantilever beam; one end of the cantilever beam is connected to the mass block, and the other end is connected to the moving component; a first groove is arranged on the upper surface of the substrate structure layer; the moving component and the cantilever beam are above the corresponding positions of the first groove; the moving component and the cantilever beam are adapted to move in the first groove.

4. The MEMS device according to claim 1, wherein: the interconnection layer comprises a conductive interconnection structure and a dielectric layer; the dielectric layer is on the upper surface of the substrate layer; the conductive interconnection structure is inside the dielectric layer; the material of the dielectric layer is silicon dioxide; the material of the conductive interconnection structure is conductive metal; a bonding layer is further arranged on the lower surface of the silicon carbide layer; the silicon carbide layer and the substrate structure layer are bonded and connected through the bonding layer and the dielectric layer; the material of the bonding layer is silicon dioxide; the thickness of the bonding layer is 20nm-500nm.

5. The MEMS device according to claim 1, wherein: the MEMS device further comprises a packaging wafer above the substrate structure layer, comprising an upper cover plate and a sidewall cover plate; the packaging wafer further surrounds the movable structure layer and forms a vacuum cavity; a second groove is arranged on the upper surface of the substrate structure layer; the sidewall cover plate is inside the second groove; the sidewall cover plate is connected to the bottom of the second groove through a metal bonding layer below.

6. A preparation method of a MEMS device, comprising: forming a substrate structure layer; the substrate structure layer comprises a substrate layer and an interconnection layer above the substrate layer; forming a movable structure layer on the upper surface of the substrate structure layer; the movable structure layer comprises a moving component and a cantilever beam at the side of the moving component; the movable structure layer comprises a silicon carbide layer and a diamond-like carbon film layer stacked from bottom to top; the silicon carbide layer is relatively close to the substrate structure layer.

7. The preparation method of the MEMS device according to claim 6, wherein: the step of forming a substrate structure layer comprises: providing a first silicon wafer; performing ion implantation on the surface of the first silicon wafer and depositing to form a dielectric layer; performing photolithography etching and metal deposition process on the upper surface of the first silicon wafer to form a conductive interconnection structure inside the dielectric layer; the remaining first silicon wafer is a substrate layer; the dielectric layer and the conductive interconnection structure inside the dielectric layer constitute an interconnection layer. The step of forming the movable structure layer further comprises: providing a packaging wafer comprising an upper cover plate and a sidewall cover plate; bonding the packaging wafer to the upper side of the base structure layer, the packaging wafer and the base structure layer forming a vacuum cavity, the movable structure layer being located in the vacuum cavity.

8. The method of claim 6, wherein the step of forming the movable structure layer comprises: forming a silicon carbide layer on the upper surface of the base structure layer; forming a diamond-like carbon film layer on the side surface of the silicon carbide layer opposite to the base structure layer by a plasma-assisted chemical vapor deposition process or a sputtering process; performing photolithography and etching on the laminated silicon carbide layer and diamond-like carbon film layer to form the movable structure layer, the movable structure layer comprising a moving component and a cantilever beam on the side of the moving component.

9. The method of claim 8, wherein the step of forming the silicon carbide layer on the upper surface of the base structure layer comprises: providing an initial silicon carbide wafer; forming a bonding layer on the surface of the initial silicon carbide wafer; bonding the bonding layer to the upper surface of the base structure layer on the side opposite to the initial silicon carbide wafer; thinning the initial silicon carbide wafer to obtain the silicon carbide layer.

10. The method of claim 8, wherein the step of forming the silicon carbide layer on the upper surface of the base structure layer comprises: providing a second silicon wafer and depositing a silicon carbide layer on the surface of the second silicon wafer; forming a bonding layer on the side surface of the silicon carbide layer opposite to the second silicon wafer; bonding the bonding layer to the upper surface of the base structure layer on the side opposite to the silicon carbide layer, and removing the second silicon wafer. ​ ​ ​

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