Method for bonding microstructured elements and microstructured assembly
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2024-12-04
- Publication Date
- 2026-07-10
AI Technical Summary
Existing technologies struggle to achieve precise spacing control and reduce misalignment during wafer bonding of microstructured components, while simultaneously establishing electrically insulating contacts between structures on different wafers.
A novel bonding method is employed, which involves setting specific bonding surfaces and coatings on the substrate surface of microstructured components. By combining direct bonding and thermocompression bonding, precise spacing alignment and connection are achieved. Combined with laser energy to control temperature, electrically insulating and conductive connections are formed.
It achieves precise spacing and electrically insulated contact of microstructure components, reduces substrate damage, and improves mechanical strength and connection reliability.
Smart Images
Figure CN122374249A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for bonding microstructured elements according to claim 1. Furthermore, this invention relates to a microstructured assembly having microstructured elements. Background Technology
[0002] In the fabrication of microelectromechanical components (MEMS devices), wafer bonding is a known method in which multiple wafers are mechanically connected at a defined spacing, where it is usually necessary to simultaneously establish electrically insulating contacts between structures on different wafers.
[0003] There are different known methods for wafer bonding, which are selected based on requirements and materials. One of the most common methods is anodic bonding, in which a silicon wafer is joined to a glass wafer using heat and voltage. This process enables the achievement of strong chemical bonds.
[0004] Another common method is direct bonding. In this case, the wafer surfaces are bonded at the molecular level through temperature and pressure. This method requires extremely clean and flat surfaces but provides high mechanical strength. Hybrid direct bonding extends direct bonding by simultaneously bonding conductive and insulating layers to each other.
[0005] Eutectic bonding uses an alloy that is introduced between wafers and melted at a specific temperature to form a bond.
[0006] In addition, there is thermocompression bonding, which allows materials, typically metals such as gold or copper, to be joined together by using heat and pressure. Summary of the Invention
[0007] According to the present invention, a bonding method having the features described in claim 1 is proposed. Therefore, microstructure elements can be connected to each other with more precise spacing and the smallest possible misalignment. Furthermore, electrically insulated contacts can be established between structures on two microstructure elements.
[0008] The first microstructure element and / or the second microstructure element may have a substrate. The substrate may have at least silicon or be made of silicon. The substrate may have at least one coating, particularly preferably a passivation layer made of silicon dioxide, on its surface.
[0009] The first microstructure element and / or the second microstructure element may be a micro-optical structure element, a microelectronic structure element, a micromechanical structure element, or a microelectromechanical structure element. The microstructure element may be a semiconductor element.
[0010] The first bonding surface and / or the third bonding surface may be formed by the substrate surface of the substrate and / or the coating surface of the coating.
[0011] The second and / or fourth bonding surfaces can be the surface of a material applied to the substrate or coating, or the surface of another coating material applied to the substrate or coating. The second and / or fourth bonding surfaces can have at least one diffusion barrier relative to the substrate. Therefore, damage to the substrate during the second bonding step can be reduced.
[0012] The first bonding surface, the second bonding surface, the third bonding surface, and / or the fourth bonding surface may be at least partially composed of silicon dioxide, silicon, aluminum, germanium, gold, silicon carbide, aluminum oxide, and / or copper.
[0013] The first bonding pair and / or the second bonding pair may be electrically insulating or conductive. If the first bonding pair is conductive, the second bonding pair may be electrically insulating, and vice versa.
[0014] Through the first bonding step, the first microstructure element and the second microstructure element can be fixed to each other via a first bonding pair. The first bonding step may include direct bonding. Thus, the first microstructure element and the second microstructure element can be mechanically fixed and connected to each other. Direct bonding can be performed between the silicon dioxide surface and the silicon surface. Therefore, electrical insulation between the first microstructure element and the second microstructure element can also be maintained after the first bonding step. In the first bonding step, the first bonding surface and the third bonding surface can come into contact with each other.
[0015] The second bonding step may include, in particular, thermocompression bonding between the two aluminum surfaces, eutectic bonding between the aluminum and germanium surfaces, or fusion bonding between the two aluminum surfaces. Therefore, a conductive connection can be established via the second bonding pair.
[0016] In a preferred embodiment of the invention, it is advantageous that alignment includes mechanical contact between the first and third bonding surfaces until axial mating. Furthermore, the alignment may include alignment toward at least one direction of a plane having the axial direction as its normal. When the first and third bonding surfaces are in mechanical contact, the second and fourth bonding surfaces may also be in mechanical contact with each other.
[0017] In an advantageous embodiment of the invention, during axial mating, the second and fourth bonding surfaces come into contact with each other earlier in time than the mechanical contact between the first and third bonding surfaces. At the point when the second and fourth bonding surfaces mechanically contact each other, the first and third bonding surfaces are still, in particular, spaced apart from each other.
[0018] A preferred configuration of the invention is advantageous in which the second and fourth bonding surfaces do not contact each other after alignment and immediately before the first bonding step, while the first and third bonding surfaces do contact each other. The second and fourth bonding surfaces may be spaced apart from each other after the first bonding step and before the second bonding step.
[0019] Not only the first and third bonding surfaces, but also the second and fourth bonding surfaces can come into contact with each other after alignment and directly before the first bonding step.
[0020] In a preferred embodiment of the invention, it is advantageous that the second bonding surface is axially elastically received on the first microstructure element and / or the fourth bonding surface is axially elastically received on the second microstructure element. The second and / or fourth bonding surfaces can be received on the substrate by at least one spring element. The spring element may include a diaphragm and / or a bent beam. The axial spacing between the third and fourth bonding surfaces may differ from the axial spacing before the first bonding step, after the first bonding step and before the second bonding step.
[0021] In a particular configuration of the invention, it is advantageous that the first and second bonding surfaces are axially offset from each other on the first microstructure element and / or the third and fourth bonding surfaces are axially offset from each other on the second microstructure element. The first and second bonding surfaces, or the third and fourth bonding surfaces, may also be axially arranged on a common plane. However, if the first and second bonding surfaces are axially arranged on a common plane, then the second and fourth bonding surfaces are axially offset from each other, and vice versa.
[0022] A preferred configuration of the invention is advantageous in which the second bonding surface is axially retracted relative to the first bonding surface and / or the fourth bonding surface is axially protruding relative to the third bonding surface. Preferably, the second bonding surface is axially protruding relative to the first bonding surface, and the fourth bonding surface is axially protruding relative to the third bonding surface. More preferably, the second bonding surface is axially protruding relative to the first bonding surface, and the fourth bonding surface is axially retracted relative to the third bonding surface.
[0023] In a preferred embodiment of the invention, it is advantageous that the second temperature is higher than the first temperature. The first temperature can be lower than 220°C, especially in the room temperature range.
[0024] The second temperature can be higher than the melting temperature, solidus temperature, and / or liquidus temperature of the material forming the second bonding surface and / or the fourth bonding surface. The second temperature can be greater than 350°C, preferably greater than 650°C.
[0025] The second temperature can be spatially restricted and applied to the region or surrounding area of the second bonding surface and / or the fourth bonding surface. The microstructure element can have the second temperature only locally during the second bonding step. The thermal energy used to apply the second temperature can be introduced by laser energy.
[0026] In a particular embodiment of the invention, it is advantageous that the first microstructure element is structured on a surface facing the second microstructure element and / or the second microstructure element is structured on a surface facing the first microstructure element. The first and / or second microstructure elements may have at least one notch, conductor rail, and / or functional layer, such as a passivation region. The notch may form a cavity between the first and second microstructure elements after bonding.
[0027] According to the present invention, a microstructure component having the features described in claim 10 is also provided. This microstructure component can be associated with microelectromechanical sensors and / or actuators. This microstructure component can be associated with a loudspeaker.
[0028] Other advantages and advantageous configurations of the invention will become apparent from the description and drawings. Attached Figure Description
[0029] The invention will now be described in detail with reference to the accompanying drawings. The drawings show in detail: Figure 1 In a particular embodiment of the present invention, a method for bonding two microstructure elements is provided.
[0030] Figure 2 : Figure 1 Other steps of the method.
[0031] Figure 3 In another particular embodiment of the invention, a method for bonding two microstructure elements is provided.
[0032] Figure 4 In another particular embodiment of the invention, a method for bonding two microstructure elements is provided.
[0033] Figure 5 : Figure 4 Other steps of the method.
[0034] Figure 6 In another particular embodiment of the invention, a method for bonding two microstructure elements is provided.
[0035] Figure 7 : Figure 6 Other steps of the method.
[0036] Figure 8 : A microstructure component in another particular embodiment of the invention. Detailed Implementation
[0037] Figure 1 A particular embodiment of the invention illustrates a method for bonding two microstructure elements. Figure 1 Figure a) shows a top view of the first microstructure element 10. Figure 1 c) shows a top view of the second microstructure element 12, and Figure 1 b) shows a cross-section of the first microstructure element 10 and a cross-section of the second microstructure element 12.
[0038] A method for bonding a first microstructure element 10 and a second microstructure element 12 includes providing a first microstructure element 10 having at least one first bonding surface 18 and a second bonding surface 20, and a second microstructure element 12 structurally separated from the first microstructure element 10 having at least one third bonding surface 22 and a fourth bonding surface 24. The first microstructure element and the second microstructure elements 10 and 12 are arranged opposite to each other in an axial direction 26.
[0039] The first microstructure element 10 includes a substrate 28, preferably made of silicon, on which a passivation layer 30 made of silicon dioxide is applied. A first bonding surface 18 is formed on the surface of the passivation layer 30. A material 32, preferably aluminum, is partially coated on the passivation layer 30. A second bonding surface 20 is formed on the surface of the material 32. The first bonding surface and the second bonding surfaces 18, 20 are arranged axially offset from each other on the first microstructure element 10. The second bonding surface 20 is axially spaced from the first bonding surface 18 by an axial distance d1 and is configured to protrude axially toward the direction of the second microstructure element 12.
[0040] The second microstructure element 12 also includes a substrate 28, preferably made of silicon, wherein a third bonding surface 22 is formed on the substrate surface. The substrate surface facing the first microstructure element 10 is structured and has at least one notch 34. Furthermore, a material 36, particularly germanium, is locally coated on the substrate surface. A fourth bonding surface 24 is formed on the surface of the material 36. The third and fourth bonding surfaces 22, 24 are arranged axially offset from each other on the second microstructure element 12. The fourth bonding surface 24 is arranged axially spaced relative to the third bonding surface 22 by an axial distance d2.
[0041] The fourth bonding surface 24 is preferably completely surrounded by a notch 38 that extends so deeply into the substrate 28 that the remaining substrate thickness 40 in the region of the notch 38 is set such that the substrate portion 42 on which the fourth bonding surface 24 is disposed can be offset in the axial direction 26 under force. Therefore, the fourth bonding surface 24 is axially and elastically received on the second microstructure element 12 by a membrane 44 on the substrate 28.
[0042] like Figure 1 As shown in b), the first and second microstructure elements 10, 12 are aligned 46 with each other to bond a first bonding pair 48 formed by a first bonding surface 18 and a third bonding surface 22 opposite in the axial direction 26 to a second bonding pair 50 formed by a second bonding surface 20 and a fourth bonding surface 24 opposite in the axial direction 26. The alignment 46 specifically includes, on the one hand, alignment 46 toward at least one direction 52 of a plane 53 having the axial direction 26 as its normal, and on the other hand, axial closing 54 until mechanical contact is made between the first and third bonding surfaces 18, 22. During axial closing 54, as shown in the dashed line of the first microstructure element 10 here, the second bonding surfaces and fourth bonding surfaces 20, 24 of the second bonding pair 50 come into contact with each other temporally earlier than the mechanical contact between the first bonding surfaces and third bonding surfaces 18, 22 of the first bonding pair 48. At the point when mechanical contact is made between the second bonding surface and the fourth bonding surface 20, 24, the first bonding surface and the third bonding surface 18, 22 are still separated from each other.
[0043] Figure 2 Show Figure 1 Other steps of the method. Figure 2 Figure a) shows the first and second microstructure elements 10 and 12 after alignment and in the first bonding step. Here, the first and second bonding surfaces 18 and 20, as well as the third and fourth bonding surfaces 22 and 24, are axially spaced from each other. The fourth bonding surface 24 is axially offset away from the first microstructure element 10 by force and elastic reception via the diaphragm 44, and has an axial distance d2' relative to the third bonding surface 22 during and after the first bonding step, which is different from the first bonding surface 10. Figure 1 The axial spacing between the third and fourth bonding surfaces 22, 24 prior to the first bonding step, as shown in b).
[0044] A first bonding step 60 is performed using the first and second microstructure elements 10 and 12, which are thus aligned, to bond the first bonding pair 48, i.e., the first bonding surface and the third bonding surfaces 18 and 22, at a first temperature. Here, the connection can be made by direct bonding.
[0045] exist Figure 2Figure b) shows a second bonding step 62 that follows immediately in time, through which the second bonding surface and the fourth bonding surfaces 20, 24 are bonded to each other at a second temperature. Here, the second bonding step 62 can be performed by eutectic bonding between the aluminum and germanium surfaces. After the second bonding step 62, the second bonding surfaces and the fourth bonding surfaces 20, 24, as well as the first microstructure element and the second microstructure element 10, 12, are also interconnected as microstructure assembly 64, in particular, they are interconnected substantially by material locking and are no longer merely in contact or pressed together.
[0046] Figure 3 In another particular embodiment of the invention, a method for bonding two microstructure elements is shown. The first and second microstructure elements 10 and 12, and the method thereof... Figure 1 The same in Figure 1 The description is incorporated herein, but with the following distinction. The fourth bonding surface 24 is the material surface of material 36 on the substrate surface of the substrate 28 of the second microstructure element 12. Material 36 is, in particular, aluminum.
[0047] A notch 66 is provided in the region of material 36 below material 36 in the axial direction, through which the fourth bonding surface 24 is axially and elastically received on the second microstructure element 12 via a diaphragm 44 in the substrate 28.
[0048] Figure 4 In another particular embodiment of the invention, a method for bonding two microstructure elements is shown. The first and second microstructure elements 10 and 12, and the method thereof... Figure 1 The same in Figure 1 The description is incorporated herein, but with the following distinctions. The fourth bonding surface 24 is arranged axially retracted relative to the third bonding surface 22 by an axial spacing d2. The fourth bonding surface 24 is the surface of the material 36, particularly aluminum. The material 36 is received in a recess 68 in the substrate 28.
[0049] Figure 5 Show Figure 4 Other steps of the method. These method steps are related to... Figure 2 The same in Figure 2 The explanation is introduced here, but the following differences exist. For example... Figure 5 As shown in a), after alignment and in the first bonding step 60, the second bonding surfaces and the fourth bonding surfaces 20, 24 of the second bonding pair 50 do not contact each other and have an axial distance d3 between them, while the first bonding surfaces and the third bonding surfaces 18, 22 of the second bonding pair 48 are in contact.
[0050] exist Figure 5b) shows a second bonding step 62 that immediately follows in time, through which the second bonding surface and the fourth bonding surfaces 20, 24 are connected to each other at a second temperature and bonded to each other thereon.
[0051] Figure 6 In another particular embodiment of the invention, a method for bonding two microstructure elements is shown. The first and second microstructure elements 10 and 12, and the method thereof... Figure 1 The same in Figure 1 The description is incorporated herein, but with the following differences. The fourth bonding surface 24 is axially retracted relative to the third bonding surface 22 by an axial spacing d2.
[0052] On the surface 72 opposite to the first microstructure element 10, the second microstructure element 12 has a protrusion 74 in the region unfolded by the fourth bonding surface 24. The protrusion 74 may have been implemented before the first bonding step, or alternatively, may be placed after the first bonding step and before the second bonding step. The protrusion 74 serves to move the fourth bonding surface 24 axially toward the first microstructure element 10 after the first bonding step by applying planar pressure to the surface 72 via the protrusion 74 until it comes into mechanical contact with the second bonding surface 20.
[0053] Figure 7 Show Figure 6 Other steps of the method. These method steps are related to... Figure 2 The same in Figure 2 The explanation is introduced here, but the following differences exist. For example... Figure 7 As shown in a), after alignment and in the first bonding step 60, the second bonding surface and the fourth bonding surface 20, 24 do not contact each other and have a gap d3 between them, while the first bonding surface and the third bonding surface 18, 22 contact each other.
[0054] exist Figure 7 b) shows a second bonding step 62 that immediately follows in time, by which the second bonding surfaces and the fourth bonding surfaces 20, 24 of the second bonding pair 50 are bonded to each other at a second temperature and thus bonded to each other.
[0055] Figure 8 A microstructure component is shown in another particular embodiment of the invention. Microstructure component 64 and... Figure 2Similar to a), but with the following differences. Microstructure component 64 is shown after the alignment of the first and second microstructure elements 10, 12 and during the first bonding step 60. The second bonding surface 20 is axially spaced from the first bonding surface 18 by an axial distance d1. Here, the second bonding surface is retracted. The fourth bonding surface 24 is axially spaced from the third bonding surface 22 by an axial distance d2 and is retracted relative to the third bonding surface. The axial distance present due to the mechanical contact between the first and third bonding surfaces 18, 22 is zero, and differs from the axial distance d3 between the second and fourth bonding surfaces 20, 24.
Claims
1. A method for bonding (14) microstructure elements, comprising the following steps: Provides (16) a first microstructure element (10) having at least one first bonding surface and a second bonding surface (18, 20) and a second microstructure element (12) having at least one third bonding surface and a fourth bonding surface (22, 24) that are structurally separated from the first microstructure element (10). The first microstructure element and the second microstructure element (10, 12) are aligned with each other (46) for subsequently bonding a first bonding pair (48) formed by the first bonding surface (18) and the third bonding surface (22) opposite in the axial direction (26) to a second bonding pair (50) formed by the second bonding surface (22) and the fourth bonding surface (24) opposite in the axial direction (26). Next, a first bonding step (60) is performed, in which the first bonding surface and the third bonding surface (18, 22) are bonded together at a first temperature. A second bonding step (62) is then performed, in which the second bonding surface and the fourth bonding surface (20, 24) are bonded to each other at a second temperature. in, The first bonding surface and the second bonding surface (18, 20) are axially spaced apart from each other by an axial distance (d1), the third and the fourth bonding surfaces (22, 24) are axially spaced apart by an axial distance (d2), and / or the second bonding surface and the fourth bonding surface (20, 24) are axially spaced apart from each other by an axial distance (d3) after the first bonding step (60) and before the second bonding step (62).
2. The bonding method (14) according to claim 1, characterized in that, The alignment (46) includes mechanical contact between the first bonding surface and the third bonding surface (18, 22) until axial closing (54).
3. The bonding method (14) according to claim 2, characterized in that, During the axial closing (54), the second bonding surface and the fourth bonding surface (20, 24) come into contact with each other earlier in time than the mechanical contact between the first bonding surface and the third bonding surface (18, 22).
4. The bonding method (14) according to any one of the preceding claims, characterized in that, After the alignment (46) and directly before the first bonding step (60), the second bonding surface and the fourth bonding surface (20, 24) are not in contact with each other, while the first bonding surface and the third bonding surface (18, 22) are in contact with each other.
5. The bonding method (14) according to any one of the preceding claims, characterized in that, The second bonding surface (20) is elastically received on the first microstructure element (10) in the axial direction and / or the fourth bonding surface (24) is elastically received on the second microstructure element (12) in the axial direction.
6. The bonding method (14) according to any one of the preceding claims, characterized in that, The first bonding surface and the second bonding surface (18, 20) are arranged axially offset from each other on the first microstructure element (10) and / or the third bonding surface and the fourth bonding surface (22, 24) are arranged axially offset from each other on the second microstructure element (12).
7. The bonding method (14) according to claim 6, characterized in that, The second bonding surface (20) is arranged in an axially retracted or axially protruding manner relative to the first bonding surface (18) and / or the fourth bonding surface (24) is arranged relative to the third bonding surface (22).
8. The bonding method (14) according to any one of the preceding claims, characterized in that, The second temperature is higher than the first temperature.
9. The bonding method (14) according to any one of the preceding claims, characterized in that, The first microstructure element (10) is structured on the surface (72) facing the second microstructure element (12) and / or the second microstructure element (12) is structured on the surface (72) facing the first microstructure element (10).
10. Microstructure component (64), having: A first microstructure element (10) having at least one first bonding surface and a second bonding surface (18, 20). A second microstructure element (12) having at least one third bonding surface and a fourth bonding surface (22, 24), wherein, The first bonding surface (18) and the third bonding surface (22) opposite each other in the axial direction form a first bonding pair (48), and the second bonding surface (20) and the fourth bonding surface (24) opposite each other in the axial direction form a second bonding pair (50), wherein the second bonding surface (20) is elastically received in the axial direction on the first microstructure element (10) and / or the fourth bonding surface (24) is elastically received in the axial direction on the second microstructure element (12).