MEMS device and manufacturing method thereof

Abstract

The invention provides an MEMS device and a manufacturing method thereof, and the MEMS device comprises a first wafer which is provided with a control circuit; the second wafer is used for forming a functional layer of the MEMS device, and the second wafer and the first wafer are bonded to form a first cavity; and the air suction structure is arranged on the first wafer and located in the first cavity, and the air suction structure comprises at least one groove. The air suction structure comprises at least one groove, and the specific surface area of the air suction structure in unit volume can be increased, so that the air suction effect is remarkably improved, and the problem that in the prior art, the air suction effect of a getter is poor is solved.

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] MEMS devices require a high-vacuum operating environment. For example, gyroscopes in inertial sensors can only meet the performance requirements for vibration frequency, sensitivity, and noise under a high-vacuum environment. However, in actual manufacturing processes, some material or residue release inevitably occurs, which leads to a decrease in the vacuum level.

[0003] To improve the vacuum level, getters with getting properties are introduced. However, existing getters have poor getting performance and cannot meet the high vacuum requirements of devices. Summary of the Invention

[0004] The problem solved by this invention is the poor getter performance of existing MEMS devices.

[0005] To address the above problems, the present invention provides a MEMS device, the MEMS device comprising: The first wafer has a control circuit. The second wafer is used to form the functional layer of the MEMS device, and the second wafer is bonded to the first wafer to form a first cavity; A suction structure is disposed on the first wafer and located within the first cavity, the suction structure including at least one groove.

[0006] Optionally, the groove can be strip-shaped or annular.

[0007] Technical benefits: The strip-shaped grooves can fit into linearly arranged cavities, allowing for even distribution to fully utilize space and guiding gas flow along its length, thus improving contact efficiency. The annular grooves form a closed gas-capturing ring, reducing gas escape.

[0008] Optionally, the cross-sectional shape of the groove is one or a combination of semi-circular, polygonal, V-shaped or U-shaped.

[0009] Technical advantages: The smooth inner wall of the semi-circular cross-section reduces gas flow resistance and facilitates gas adsorption. The polygonal shape, through the combination of multiple edges and planes, increases the local specific surface area and improves the density of adsorption points per unit volume; the V-shape, with its sharp bottom, forms a gas convergence zone, enhancing the ability to capture diffused gases; the U-shape has surface integrity, facilitating uniform gas contact.

[0010] Optionally, adjacent grooves may be adjacent to each other or spaced apart.

[0011] Technical benefits: The adjacent arrangement of grooves maximizes the density of groove distribution per unit area, significantly increasing the overall specific surface area through the dense surface structure and enhancing the adsorption capacity for gases. Meanwhile, the spaced design provides ample channels for gas flow, avoiding gas diffusion obstruction caused by excessively dense grooves, ensuring that gas can efficiently reach the surface of each groove and improving adsorption efficiency.

[0012] Optionally, the orthographic projection of the gas-absorbing structure on the first wafer is circular, and the at least one groove is distributed at intervals around the center of the circle.

[0013] Optionally, the MEMS device further includes a capping wafer, the capping wafer having a second cavity, the capping wafer being bonded to the side of the second wafer away from the first wafer to seal the second cavity, the projections of the second cavity and the first cavity on the surface of the second wafer partially or completely overlapping.

[0014] This application also provides a method for fabricating a MEMS device, the method comprising: A first wafer is provided, the first wafer being provided with control circuitry; A gas-absorbing structure is provided on one side of the first wafer, the gas-absorbing structure including at least one groove; A second wafer is provided, the second wafer being used to form the functional layer of the MEMS device; The second wafer is bonded to one side of the first wafer to form a first cavity, and the gas-absorbing structure is located within the first cavity.

[0015] Optionally, the step of providing a gas-suction structure on one side of the first wafer includes: A patterned photoresist is formed on one side of the first wafer; A getter material is deposited on the photoresist and the first wafer, and the photoresist and the getter material on the photoresist are stripped to obtain a pre-getter structure; A patterned photoresist is formed on one side of the first wafer and the pre-absorption structure; A getter material is deposited on the photoresist and the pre-getter structure, and the photoresist and the getter material on the photoresist are stripped off to obtain the getter structure.

[0016] Optionally, the step of providing a gas-suction structure on one side of the first wafer includes: A getter material is deposited on one side of the first wafer; A patterned photoresist is formed on one side of the getter material; The getter material is etched to form a pre-getter structure; Patterned photoresist is formed on the pre-absorption structure and the photoresist; The pre-absorption structure is etched, and the photoresist is removed to form the absorptive structure.

[0017] Optionally, the manufacturing method further includes: A capped wafer is provided, wherein the capped wafer is provided with a second cavity; The capping wafer is bonded to the side of the second wafer away from the first wafer to seal the second cavity; The projections of the second cavity and the first cavity onto the surface of the second wafer partially or completely overlap.

[0018] The MEMS device provided in this application includes a first wafer, a second wafer, and a getter structure. The second wafer is bonded to the first wafer to form a first cavity. The getter structure is disposed on the first wafer and located within the first cavity, and the getter structure includes at least one groove. By including at least one groove in the getter structure, the specific surface area of ​​the getter structure per unit volume can be increased, thereby significantly improving the getter effect and solving the problem of poor getter effect in the prior art. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the MEMS device provided in the embodiments of this application; Figure 2 for Figure 1 The diagram shows a schematic of the first type of air intake structure in the MEMS device. Figure 3 for Figure 1 The diagram shows a second type of air-absorbing structure in the MEMS device. Figure 4 A schematic flowchart illustrating the fabrication method of the MEMS device provided in the embodiments of this application; Figure 5 for Figure 4 The diagram shows a first process flow diagram with an air intake structure in the manufacturing method shown. Figure 6 for Figure 5 The process flow diagram corresponding to the manufacturing method shown; Figure 7 for Figure 4 The diagram shows a second process flow diagram with an air intake structure in the manufacturing method shown. Figure 8 for Figure 7 The process flow diagram corresponding to the manufacturing method shown.

[0020] Explanation of reference numerals in the attached figures: 1. MEMS device; 11. First wafer; 12. Second wafer; 13. Gas-absorbing structure; 14. First cavity; 15. Capping wafer; 16. Second cavity; 131. Groove; 201. Photoresist; 202. Gas-getting material; 203. Pre-gas-getting structure. Detailed Implementation

[0021] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0022] To improve vacuum levels, introducing and applying getters in MEMS devices is an important and common method. Commonly used getters include titanium-based and zirconia-based getters, which lack getter function or only provide minimal gettering at lower temperatures. However, upon activation at temperatures above a certain level, they rapidly absorb gas and significantly reduce vacuum levels, thus meeting the high vacuum requirements of the devices. To enhance the getter's effectiveness, materials with strong getter properties are typically selected. Furthermore, the thickness and porosity of the getter need to be controlled; theoretically, more porous materials offer better getter performance. Theoretically, a larger specific surface area per unit volume results in better getter performance.

[0023] However, in practical applications, the volume available for placing the getter is limited. Therefore, maximizing the specific surface area within a limited volume becomes the key to solving the problem of poor getter performance.

[0024] To address the aforementioned technical problems, this application provides a MEMS device. Please refer to [link / reference]. Figure 1 , Figure 1 This is a schematic diagram of the structure of a MEMS device provided in an embodiment of this application. The MEMS device 1 includes a first wafer 11, a second wafer 12, and a getter structure 13. The first wafer 11 has a control circuit; the second wafer 12 is used to form the functional layer of the MEMS device 1, and the second wafer 12 is bonded to the first wafer 11 to form a first cavity 14; the getter structure 13 is disposed on the first wafer 11 and located in the first cavity 14, and the getter structure 13 includes at least one groove 131. By providing the getter structure 13 with at least one groove 131, the specific surface area of ​​the getter structure 13 per unit volume can be increased, thereby significantly improving the getter effect and solving the problem of poor getter effect in the prior art.

[0025] In some embodiments, the groove 131 is either strip-shaped or annular. The strip-shaped groove 131 can adapt to linearly arranged cavities, can be evenly distributed to fully utilize space, and can guide gas flow along its length, improving contact efficiency. The annular groove 131 can form a closed gas trapping ring, reducing gas escape. Both shapes are technologically mature and easy to manufacture, reducing production difficulty and cost, while improving suction performance and avoiding structural stability issues that might arise from complex shapes.

[0026] It is understandable that the shape of each groove 131 can be set according to actual needs. It can be a strip or a ring, or a combination of a part strip and a part ring. No specific restrictions are imposed here.

[0027] In some embodiments, the cross-sectional shape of the groove 131 is one or a combination of semicircular, polygonal, V-shaped, or U-shaped. It is understood that a semicircular cross-section has a smooth inner wall, reducing gas flow resistance and facilitating gas adsorption. A polygon, through the combination of multiple edges and planes, can increase the local specific surface area and improve the adsorption point density per unit volume; a V-shape, with its sharp bottom, forms a gas convergence zone, enhancing the ability to capture diffused gases. A U-shape has surface integrity, facilitating uniform gas contact. Furthermore, the combined form can flexibly integrate the advantages of different shapes. For example, when semicircular and V-shaped are combined, smooth flow characteristics are maintained while enhancing the local adsorption effect. This allows for more precise control over adapting to complex cavity structures, optimizing gas adsorption paths, and balancing processing difficulty with increased specific surface area, further enhancing the overall efficiency of the suction structure 13.

[0028] In some embodiments, adjacent grooves 131 are either adjacent to each other or spaced apart. It is understood that an adjacent arrangement maximizes the distribution density of grooves 131 per unit area, significantly increasing the overall specific surface area through a dense surface structure and enhancing the gas adsorption capacity. A spaced design provides ample channels for gas flow, avoiding gas diffusion obstruction caused by excessively dense grooves 131, ensuring that gas can efficiently reach the surface of each groove 131, thus improving adsorption efficiency. Both layout options can be flexibly selected based on the gas flow characteristics within the cavity, space size, and air intake priority, achieving precise control of the air intake effect while ensuring structural stability, further broadening the applicability of the air intake structure 13.

[0029] It should be noted that the MEMS device 1 can be configured with multiple air intake structures 13 according to the actual situation. The shape, cross-sectional shape and arrangement of adjacent grooves 131 of each air intake structure 13 can be completely the same, partially the same or different from each other. The specific configuration can be set according to the actual situation, and no specific restrictions are imposed here.

[0030] Please continue reading. Figure 2 , Figure 2 for Figure 1 The diagram shows a first structural schematic of the gas-absorbing structure in a MEMS device. In some embodiments, the orthographic projection of the gas-absorbing structure 13 onto the first wafer 11 is circular, with at least one groove 131 spaced apart around the center of the circle. The depth of each groove 131 may be the same or different, and can be set according to actual conditions, without specific limitations here.

[0031] Please continue reading. Figure 3 , Figure 3 for Figure 1 The diagram shows a second structural schematic of the gas-absorbing structure in the MEMS device. In some embodiments, the orthographic projection shape of the gas-absorbing structure 13 on the first wafer 11 is quadrilateral, and a plurality of grooves 131 on the gas-absorbing structure 13 are arrayed. The depth, shape, and cross-section of each groove 131 may be the same or different, and can be set according to the actual situation, without specific limitations here.

[0032] In some embodiments, the surface of the suction structure 13 is honeycomb-shaped. The honeycomb structure significantly increases the specific surface area; specifically, the numerous dense pores greatly increase the contact area with the gas, thereby improving adsorption efficiency. Simultaneously, the uniform pore distribution of this structure allows for smoother gas flow, reducing flow resistance and ensuring full contact between the gas and the adsorption surface. Furthermore, the honeycomb structure possesses excellent structural stability, guaranteeing sufficient porosity per unit volume while being resistant to damage from external forces or temperature changes. This balances suction performance with the mechanical properties of the device, effectively optimizing the overall performance of the suction structure 13.

[0033] See again Figure 1 The MEMS device 1 also includes a capping wafer 15, which has a second cavity 16. The capping wafer 15 is bonded to the side of the second wafer 12 away from the first wafer 11 to seal the second cavity 16. The projections of the second cavity 16 and the first cavity 14 on the surface of the second wafer 12 partially or completely overlap.

[0034] Please continue reading. Figure 4 , Figure 4 This is a schematic flowchart illustrating the fabrication method of a MEMS device provided in this application embodiment. This application embodiment also provides a method for fabricating a MEMS device 1, which is used to fabricate the aforementioned MEMS device 1. The specific flow of this fabrication method is as follows: 110. A first wafer is provided, the first wafer being provided with control circuitry.

[0035] The material of the first wafer 11 includes semiconductor materials such as silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors. It can also be a double-side polished wafer (DSP), or a ceramic substrate such as alumina, quartz, or glass substrate.

[0036] 120. A gas-suction structure is provided on one side of the first wafer, the gas-suction structure including at least one groove.

[0037] The gas-absorbing structure 13 can be formed on one side of the first wafer 11 according to the lift-off process or etching process. For an example, please refer to [link to relevant documentation]. Figure 5 and Figure 6 , Figure 5 for Figure 4 The diagram shows the first process flow diagram of the manufacturing method that includes an air intake structure. Figure 6 for Figure 5 The process flow diagram corresponding to the manufacturing method shown is as follows: The specific process for setting up the suction structure 13 is as follows: 121. A patterned photoresist is formed on one side of the first wafer.

[0038] Patterned photoresist 201 can be fabricated on one side of the first wafer 11 by spin-coating photoresist 201, exposure, and development.

[0039] 122. Deposit getter material on photoresist and the first wafer, and strip the photoresist and the getter material on the photoresist to obtain a pre-getter structure.

[0040] For example, a getter material 202 is deposited to simultaneously cover the surface of the photoresist 201 and the first wafer 11 region not covered by the photoresist 201. Subsequently, the photoresist 201 and the getter material 202 attached to its surface are removed by a stripping process, while the getter material 202 in the area not covered by the photoresist 201 is retained, and the structure formed therefrom is the pre-getter structure 203.

[0041] The selective retention of the gas-seeking material 202 is achieved through the masking effect of the photoresist 201. This not only provides a basic shape for subsequent secondary processing, but also allows for the preliminary planning of the distribution range and basic outline of the pre-gas-seeking structure 203 through the design of the photoresist 201 pattern. This lays the foundation for the precise forming of the final gas-seeking structure, while effectively reducing material waste and improving process efficiency.

[0042] 123. A patterned photoresist is formed on one side of the first wafer and the pre-absorption structure.

[0043] Patterned photoresist 201 can be fabricated on one side of the first wafer 11 and the pre-absorption structure 203 by spin coating photoresist 201, exposure, and development.

[0044] 124. Deposit getter material on photoresist and pre-getter structure, and strip the photoresist and getter material on the photoresist to obtain getter structure.

[0045] For example, getter material 202 is deposited again on the surface of pre-getter structure 203 and photoresist 201, at which time getter material 202 covers the exposed area of ​​pre-getter structure 203 and the surface of photoresist 201. Then, the photoresist 201 and the getter material 202 on its surface are peeled off, and the newly deposited getter material 202 in the area of ​​pre-getter structure 203 not covered by photoresist 201 is integrated with the original pre-getter structure 203 to form getter structure 13.

[0046] By employing a two-step patterning photoresist design, the deposition area of ​​the getter material 202 can be controlled by adjusting the pattern of the photoresist 201, allowing the final getter structure 13 to exhibit complex three-dimensional shapes as needed. Furthermore, the step-by-step stripping process precisely preserves the getter material 202 in the target area, reducing material waste in unnecessary areas. Simultaneously, the secondary deposition can specifically enhance the material thickness or density in key adsorption areas, thereby forming the corresponding groove pattern 131. This design maximizes the effective getter area within a limited volume, optimizing the balance between getter performance and material cost.

[0047] Please continue reading. Figure 7 and Figure 8 , Figure 7 for Figure 4 The diagram shows the first process flow diagram of the manufacturing method that includes an air intake structure. Figure 8 for Figure 7 The process flow diagram corresponding to the manufacturing method shown is as follows: The specific process for setting up the suction structure 13 is as follows: 125. Deposit getter material on one side of the first wafer.

[0048] The getter material 202 is uniformly coated on the surface of the first wafer 11 by processes such as sputtering, evaporation or chemical vapor deposition.

[0049] 126. A patterned photoresist is formed on one side of the gas-absorbing material.

[0050] Patterned photoresist 201 is created on one side of the gas-absorbing material 202 by spin-coating photoresist 201, exposure, and development.

[0051] 127. Etch the getter material to form a pre-getter structure.

[0052] For example, photoresist 201 serves as a mask to protect the gas-absorbing material 202 of its covered area, while the unmasked portion is selectively removed by dry etching or wet etching, leaving a pre-gas-absorbing structure 203.

[0053] 128. A patterned photoresist is formed on the pre-absorption structure and the photoresist.

[0054] A new patterned photoresist 201 is created on the pre-absorption structure 13 and the residual photoresist 201 by spin coating the photoresist 201, exposure, and development.

[0055] 129. Etch the pre-absorption structure and remove the photoresist to form the absorptive structure.

[0056] By first depositing the getter material 202 and then etching it stepwise with two patterned photoresist 201 layers to form the getter structure 13, the groove 131 structure was precisely fabricated, significantly increasing the specific surface area per unit volume. Simultaneously, the stepwise etching process allows for flexible control of the etching depth and range in different areas through differentiated design of the photoresist 201 pattern. This ensures the structural integrity of key adsorption areas while avoiding material redundancy in non-target areas, reducing etching waste. Furthermore, the etching process enables precise removal of the getter material 202, ensuring a high degree of consistency between the final structure and the design dimensions. This improves getter efficiency while also considering process stability and material utilization.

[0057] It is understood that the specific ways in which the gas-absorbing structure 13 is set on one side of the first wafer 11 are not limited to the two methods mentioned above. The above process methods are only illustrative examples and not limitations on specific implementation methods.

[0058] 130. Provide a second wafer for forming the functional layer of a MEMS device.

[0059] The second wafer 12 has a functional layer on its surface or inside. The functional layer is configured according to the function of the MEMS device 1, and no specific restrictions are made here.

[0060] 140. The second wafer is bonded to one side of the first wafer to form a first cavity, and the gas-absorbing structure is located in the first cavity.

[0061] The first wafer 11 and the second wafer 12 can be bonded together by a bonding layer, or by Si-Si direct bonding.

[0062] The bonding layer can be germanium, which can be used to electrically connect the functional layer and the control circuit.

[0063] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A MEMS device, characterized in that, The MEMS device includes: The first wafer has a control circuit. The second wafer is used to form the functional layer of the MEMS device, and the second wafer is bonded to the first wafer to form a first cavity; A suction structure is disposed on the first wafer and located within the first cavity, the suction structure including at least one groove.

2. The MEMS device according to claim 1, characterized in that, The groove is either strip-shaped or ring-shaped.

3. The MEMS device according to claim 1, characterized in that, The cross-sectional shape of the groove is one or a combination of semi-circular, polygonal, V-shaped or U-shaped.

4. The MEMS device according to claim 1, characterized in that, The adjacent grooves are either adjacent to each other or spaced apart.

5. The MEMS device according to claim 1, characterized in that, The orthographic projection of the gas-absorbing structure onto the first wafer is circular, and the at least one groove is distributed at intervals around the center of the circle.

6. The MEMS device according to any one of claims 1 to 5, characterized in that, The MEMS device further includes a capping wafer, which has a second cavity. The capping wafer is bonded to the side of the second wafer away from the first wafer to seal the second cavity. The projections of the second cavity and the first cavity on the surface of the second wafer partially or completely overlap.

7. A method for fabricating a MEMS device, characterized in that, The manufacturing method includes: A first wafer is provided, the first wafer being provided with control circuitry; A gas-absorbing structure is provided on one side of the first wafer, the gas-absorbing structure including at least one groove; A second wafer is provided, the second wafer being used to form the functional layer of the MEMS device; The second wafer is bonded to one side of the first wafer to form a first cavity, and the gas-absorbing structure is located within the first cavity.

8. The manufacturing method according to claim 7, characterized in that, The provision of a gas-absorbing structure on one side of the first wafer includes: A patterned photoresist is formed on one side of the first wafer; A getter material is deposited on the photoresist and the first wafer, and the photoresist and the getter material on the photoresist are stripped to obtain a pre-getter structure; A patterned photoresist is formed on one side of the first wafer and the pre-absorption structure; A getter material is deposited on the photoresist and the pre-getter structure, and the photoresist and the getter material on the photoresist are stripped off to obtain the getter structure.

9. The manufacturing method according to claim 7, characterized in that, The provision of a gas-absorbing structure on one side of the first wafer includes: A getter material is deposited on one side of the first wafer; A patterned photoresist is formed on one side of the getter material; The getter material is etched to form a pre-getter structure; Patterned photoresist is formed on the pre-absorption structure and the photoresist; The pre-absorption structure is etched, and the photoresist is removed to form the absorptive structure.

10. The manufacturing method according to any one of claims 7 to 9, characterized in that, The manufacturing method further includes: A capped wafer is provided, wherein the capped wafer is provided with a second cavity; The capping wafer is bonded to the side of the second wafer away from the first wafer to seal the second cavity; The projections of the second cavity and the first cavity onto the surface of the second wafer partially or completely overlap.

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