sensor

Abstract

This application provides a sensor, relating to the field of semiconductor technology. The sensor includes a first wafer and a second wafer. The first wafer has a first bonding surface with a first limiting member. The second wafer has a second bonding surface opposite to the first bonding surface with a second limiting member. During the bonding process between the first and second wafers, the first and second limiting members mutually limit each other to restrict the offset distance between the first and second wafers within a preset range. This application solves the problem of bonding misalignment caused by relative wafer misalignment during high-temperature bonding processes in the prior art, and realizes a sensor that can effectively suppress wafer bonding misalignment, improve bonding accuracy, and increase product yield.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more particularly to a sensor. Background Technology

[0002] With the rapid development of automotive electronics, consumer electronics, and industrial control, the performance and reliability requirements for sensors, especially microelectromechanical systems (MEMS) devices such as inertial measurement units, are becoming increasingly stringent. These sensors are composed of wafers stacked through bonding processes, and their internal environment needs to be formed and maintained in a long-term vacuum or specific pressure environment to ensure detection accuracy and functional stability.

[0003] In existing sensor manufacturing processes, wafer bonding is a key step in achieving device stack-up structures and hermetically sealed packaging. To obtain high-quality bonding interfaces, the wafer is typically subjected to high-temperature heating before bonding to effectively remove adsorbed moisture from the wafer surface, thereby ensuring the sealing of the bonding interface and the long-term maintenance of the vacuum level inside the device.

[0004] However, high-temperature processing softens the bonding materials (such as the aluminum layer) on the wafer surface, increasing the adhesion between the wafer and the jig. In subsequent processes, when the jig is removed from the wafer, it can easily cause wafer misalignment. If this misalignment exceeds the process specifications, it will directly compromise alignment accuracy and bonding quality, causing hermeticity failure of the semiconductor, or even rendering it unusable. Summary of the Invention

[0005] This application provides a sensor to solve the problem of bonding misalignment caused by relative wafer misalignment during high-temperature bonding processes in the prior art, and to realize a sensor that can effectively suppress wafer bonding misalignment and improve bonding accuracy and product yield.

[0006] This application provides a sensor, including: a first wafer and a second wafer, the first wafer having a first bonding surface and a first limiting member thereon; the second wafer having a second bonding surface opposite to the first bonding surface and a second limiting member thereon; wherein, during the bonding process between the first wafer and the second wafer, the first limiting member and the second limiting member mutually limit each other to limit the offset distance between the first wafer and the second wafer after bonding is completed within a preset range.

[0007] According to the sensor provided in the embodiments of this application, one of the first limiting member and the second limiting member has a protrusion, and the other of the first limiting member and the second limiting member has a recess; the shapes of the protrusion and the recess are adapted to each other, and during the bonding process, the protrusion extends into the interior of the recess, and the outer wall of the protrusion abuts against the inner wall of the recess to guide the first wafer and the second wafer.

[0008] According to the sensor provided in the embodiments of this application, the outer wall of the protrusion is provided with a first guide slope, and the inner wall of the recess is provided with a second guide slope; during the bonding process, the first guide slope and the second guide slope abut against each other to guide the first wafer and the second wafer.

[0009] According to the sensor provided in the embodiments of this application, the protrusion is provided with a first convex surface at one end near the recess, and / or the recess is provided with a second convex surface at one end near the protrusion.

[0010] According to the sensor provided in the embodiments of this application, both the first wafer and the second wafer are provided with bonding portions; at least one of the first wafer and the second wafer is provided with a baffle, the baffle being located outside the bonding portion; during the bonding process, the baffle abuts against the first wafer or the second wafer to prevent the molten bonding portion from overflowing.

[0011] According to the sensor provided in the embodiments of this application, the barrier and the protrusion are both located on the first wafer, or the barrier and the protrusion are both located on the second wafer. When the barrier abuts against the first wafer or the second wafer, the protrusion abuts against the bottom end of the recess.

[0012] According to the sensor provided in the embodiments of this application, there are multiple first limiting members, which are arranged at intervals along the circumference of the first bonding surface; there are multiple second limiting members, which are arranged at intervals along the circumference of the second bonding surface; the first limiting members and the second limiting members are configured in a one-to-one correspondence.

[0013] According to the sensor provided in the embodiments of this application, the first limiting member is disposed on the first wafer by deposition and etching, and the second limiting member is disposed on the second wafer by deposition and etching.

[0014] According to the sensor provided in the embodiments of this application, the first limiting member and the second limiting member limit each other in the circumferential and / or radial directions.

[0015] According to the sensor provided in the embodiments of this application, the preset range is greater than or equal to 0 micrometers and less than or equal to 10 micrometers.

[0016] This application provides a sensor that incorporates a limiting mechanism on the first bonding surface of a first wafer and the second bonding surface of a second wafer. During the bonding process, when the first and second wafers exhibit relative displacement, the first and second limiting members contact and abut against each other, thereby limiting the offset distance between them within a preset range. This design solves the wafer displacement problem and effectively improves the alignment accuracy and product yield of the bonding process. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1 A state diagram showing the mutual offset between the first and second wafers of the sensor provided in this application before bonding;

[0019] Figure 2 A state diagram of the sensor provided in this application when bonding is complete;

[0020] Figure 3 A schematic diagram of the protrusions and recesses of the sensor provided in this application;

[0021] Figure 4 One of the schematic cross-sectional views of the structure of the first limiting member of the sensor provided in this application;

[0022] Figure 5 A schematic cross-sectional view of the structure of the second limiting member of the sensor provided in this application;

[0023] Figure 6 A second cross-section of the structural schematic diagram of the first limiting member of the sensor provided in this application;

[0024] Figure 7 The diagram shows the structure of the first and second limiting members in the sensor provided in this application.

[0025] Explanation of reference numerals in the attached figures:

[0026] 100: First wafer; 110: First bonding surface; 120: Protrusion; 130: Bonding portion; 140: Barrier; 121: First guide ramp; 122: First convex surface;

[0027] 200: Second wafer; 210: Second bonding surface; 220: Recessed portion; 221: Second guide slope; 222: Second convex surface; 223: Limiting block. Detailed Implementation

[0028] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0029] As described in the background section, wafer bonding is a crucial step in existing sensor manufacturing processes to achieve device stack-up structures and hermetically sealed packaging. To obtain high-quality bonding interfaces, the wafer is subjected to high-temperature heating before bonding to effectively remove adsorbed moisture from the wafer surface, thereby ensuring the sealing of the bonding interface and the long-term maintenance of the vacuum level inside the device.

[0030] However, high-temperature processing softens the bonding materials (such as the aluminum layer) on the wafer surface, increasing the adhesion between the wafer and the jigs and spacers. In subsequent processes, when the jigs and spacers are removed from the wafer, wafer misalignment is highly likely. If this misalignment exceeds process specifications, it will directly compromise alignment accuracy and bonding quality, causing hermeticity failure of the semiconductor, or even rendering it unusable.

[0031] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0032] Reference Figure 1 and Figure 2 The sensor provided in this application includes: a first wafer 100 and a second wafer 200. The first wafer 100 has a first bonding surface 110, and the first bonding surface 110 is provided with a first limiting member. The second wafer 200 has a second bonding surface 210 opposite to the first bonding surface 110, and the second bonding surface 210 is provided with a second limiting member. During the bonding process between the first wafer 100 and the second wafer 200, the first limiting member and the second limiting member mutually limit each other to restrict the offset distance between the first wafer 100 and the second wafer 200 after bonding is completed within a preset range. It should be noted that, for ease of description, the first wafer 100 and the second wafer 200 will be referred to simply as wafers in the following description, and the first limiting member and the second limiting member will be referred to simply as limiting members.

[0033] Specifically, the first wafer 100 refers to a device wafer that carries micromechanically sensitive structures in the microelectromechanical system (MEMS) manufacturing process, such as the silicon substrate containing the vibrating mass block and detection electrodes of an inertial measurement unit. The second wafer 200 refers to a cover wafer used to form a sealed protective cavity, made of silicon or glass. The first bonding surface 110 is a surface on the first wafer 100 used for bonding with the second wafer 200, and the second bonding surface 210 is a surface on the second wafer 200 used for bonding with the first bonding surface 110. In actual products, the first and second limiting members can be arranged in the dicing channel in areas that do not form effective devices, thus not occupying the effective layout area of ​​the chip.

[0034] During the bonding process, the first wafer 100 and the second wafer 200 are respectively loaded onto the upper and lower stages within the bonding cavity of the bonding equipment, and the first wafer is fixed by clamps and spacers. At this time, the temperature inside the bonding cavity is 100°C. The optical alignment system of the equipment achieves initial horizontal alignment between the first and second limiting members. Subsequently, the bonding equipment is evacuated and heated to 400°C, thus placing the first wafer 100 and the second wafer 200 in a high-temperature and vacuum environment. In this environment, the aluminum material of the first wafer 100 softens and easily adheres to the clamps and spacers. When the clamps and spacers are pulled out from between the first wafer 100 and the second wafer 200, it causes the first wafer 100 to shift horizontally relative to the second wafer 200 (this horizontal shift is the offset between the first wafer 100 and the second wafer 200 before bonding, and this offset is less than or equal to 15 micrometers). At the same time, the first wafer 100 and the second wafer 200 move closer to each other. During the approach process, although the first wafer 100 and the second wafer 200 have shifted, the sidewall of the first limiting member will come into contact with the sidewall of the second limiting member. This contact generates a blocking force opposite to the shift direction, controlling the relative position of the first wafer 100 and the second wafer 200 within a preset range.

[0035] This embodiment establishes a limiting mechanism on the first bonding surface 110 of the first wafer 100 and the second bonding surface 210 of the second wafer 200. During the bonding process, when the first wafer 100 and the second wafer 200 exhibit relative displacement, the first limiting member and the second limiting member contact and abut against each other, thus limiting the offset distance between them within a preset range. This design solves the wafer displacement problem and effectively improves the alignment accuracy and product yield of the bonding process.

[0036] Reference Figures 1 to 3 In some embodiments of this application, one of the first limiting member and the second limiting member has a protrusion 120, and the other of the first limiting member and the second limiting member has a recess 220; the shapes of the protrusion 120 and the recess 220 are adapted to each other, and during the bonding process, the protrusion 120 extends into the recess 220, and the outer wall of the protrusion 120 abuts against the inner wall of the recess 220 to guide the first wafer 100 and the second wafer.

[0037] Specifically, when the first limiting member has a protrusion 120, the cross-section of the protrusion 120 can be a trapezoidal or semi-circular column, and its bottom is fixedly connected to the first bonding surface 110. When the second limiting member has a recess 220, the recess 220 can be a blind hole formed on the second bonding surface 210 by an etching process, and its opening shape matches the cross-sectional shape of the protrusion 120. In a specific process, the protrusion 120 can be achieved by etching, and the final size and morphology of the protrusion 120 can be adjusted by controlling the etching parameters.

[0038] Furthermore, the protrusion 120 has a frustum-shaped structure, and its bottom surface is connected to the second wafer 200. The recess 220 can be specifically composed of two spaced-apart limiting blocks 223, both of which are also frustum-shaped structures. The gap formed between the two limiting blocks 223 constitutes the recess 220, and the bottom surfaces of the two limiting blocks 223 are connected to the first wafer 100.

[0039] Reference Figure 3 The height of the protrusion 120 is h1, and the height of the two limiting blocks 223 is h2, with h1 greater than h2. The angle between the bottom surface of the protrusion 120 and its side surface is β, and the angle between the bottom surface of the limiting block 223 and its side surface is α, with α greater than or equal to β and α less than 90°. The distance between the bottom surfaces of the two limiting blocks 223 is b, the diameter of the top surface of the protrusion 120 is a, and x is the preset offset range after bonding, then x = (ba) / 2. c is the difference in radii between the two bottom surfaces of the limiting blocks 223. The sum of c and x is the offset between the first wafer 100 and the second wafer 200 before bonding, i.e., c + x ≤ 15 micrometers.

[0040] During the bonding process, the first wafer 100 and the second wafer 200 are horizontally offset due to the removal of the jig and spacer. As the first wafer 100 and the second wafer 200 approach each other, the protrusion 120 first approaches the opening of the recess 220. The outer wall of the protrusion 120 comes into contact with the inner wall of the recess 220. As the bonding pressure continues to be applied, the protrusion 120 slides along the inner wall of the recess 220. The lateral force exerted by the inner wall of the recess 220 (i.e., the outer wall of the limiting block 223) on the outer wall of the protrusion 120 pushes the wafer to gradually adjust its position, causing the protrusion 120 to gradually slide towards the center of the recess 220. When the protrusion 120 is fully inserted into the recess 220, the outer and inner walls of the two form abutting state. At this time, the relative positions of the first wafer 100 and the second wafer 200 in the horizontal direction are fixed, and the offset is limited within the fitting gap between the protrusion 120 and the recess 220.

[0041] This embodiment constructs the protrusion 120 and the recess 220 as a simple and effective mechanical guiding and limiting mechanism. During the bonding process, the protrusion 120 extends into the interior of the recess 220, and the mutual abutment relationship between the outer and inner walls of the two forms a constraint, limiting the relative movement of the first wafer 100 and the second wafer 200 in the horizontal plane within the mating gap between the protrusion 120 and the recess 220. This structure not only passively prevents displacement when the jig and shim are withdrawn, but also plays an active guiding role during the process of the protrusion 120 entering the recess 220, guiding the first wafer 100 and the second wafer 200 to gradually return to a precise alignment state, significantly improving the accuracy and reliability of bonding alignment.

[0042] In other possible embodiments, the protrusion 120 can be disposed on the second wafer 200, while the recess 220 is disposed on the first wafer 100. This design can also achieve guiding and limiting functions. Specifically, during the fabrication of the cover wafer, the protrusion 120 can be formed simultaneously in the baffle fabrication process; when the bonding ring is fabricated on the device wafer, the recess 220 is formed at the corresponding position. The advantage of this design is that it can be flexibly selected according to the layout of existing structures on different wafers, avoiding interference with other existing microstructures. For example, when there are already many sensitive structures on the surface of the device wafer and it is not suitable to add the protrusion 120, the protrusion 120 can be arranged on the cover wafer, and the device wafer only needs to fabricate the recess 220, which is beneficial to protect the precision microstructures on the device wafer.

[0043] Reference Figures 3 to 5 In some embodiments of this application, the outer wall of the protrusion 120 is provided with a first guide slope 121, and the inner wall of the recess 220 is provided with a second guide slope 221; during the bonding process, the first guide slope 121 and the second guide slope 221 abut against each other to guide the first wafer 100 and the second wafer.

[0044] Specifically, the first guide slope 121 is an inclined surface provided on the outer wall of the protrusion 120. This slope can be a continuous slope along the circumference of the protrusion 120, or it can be provided only on each of the four sides of the protrusion 120. The second guide slope 221 is a corresponding inclined surface provided on the inner wall of the recess 220, and its inclination angle matches that of the first guide slope 121. For example, the protrusion 120 can be designed as a frustum shape, with its four sides being the first guide slope 121, and the recess 220 can be designed as a corresponding inverted frustum shape, with its four inner walls being the second guide slope 221. The inclination angle of the slopes can be precisely controlled by etching.

[0045] Furthermore, the first guide slope 121 and the second guide slope 221 are in a surface contact fit. To ensure smooth fit of the slopes, the surface roughness of the first guide slope 121 and the second guide slope 221 needs to be controlled at a low level, for example, by optimizing the etching process parameters to make the surface roughness meet the guiding requirements. The tilt angle of the slopes needs to be precisely designed; too small an angle will result in insufficient guiding effect, while too large an angle will increase the resistance when the protrusion 120 is inserted. The first guide slope 121 extends downward from the top of the protrusion 120 until it connects with the root of the protrusion 120; the second guide slope 221 extends inward from the opening edge of the recess 220 until it connects with the bottom of the recess 220.

[0046] When the protrusion 120 with the first guide bevel 121 begins to enter the recess 220 with the second guide bevel 221, the wedge effect of the bevels begins to take effect. If the first wafer 100 and the second wafer 200 are horizontally misaligned, the first guide bevel 121 first contacts the second guide bevel 221. As bonding pressure is continuously applied, the normal pressure between the two bevels is decomposed into vertical and horizontal components, with the horizontal component pushing the wafer towards the center. The protrusion 120 continues to slide down the bevels, and the misalignment gradually decreases until the two bevels are completely aligned, at which point the first wafer 100 and the second wafer 200 achieve precise alignment. The entire process is similar to the self-centering mechanism of a wedge slider, achieving automatic correction.

[0047] Reference Figure 5 and Figure 6 In some embodiments of this application, the protrusion 120 is provided with a first convex surface 122 at one end near the recess 220, and / or the recess 220 is provided with a second convex surface 222 at one end near the protrusion 120.

[0048] Specifically, the first convex surface 122 is a curved surface structure disposed on the outer periphery of the protrusion 120 near the recess 220. This curved surface can be a circular arc surface, an ellipsoidal surface, or a hemispherical surface, and its function is to eliminate the sharp edges of the protrusion 120. The second convex surface 222 is a curved surface structure disposed on the inner wall of the recess 220 near the protrusion 120, and its function is to eliminate the sharp edges at the opening of the recess 220. For example, the first convex surface 122 can be a transition arc formed by rounding the four edges of the protrusion 120, and the radius of the arc can be achieved by controlling the sidewall morphology of the etching process.

[0049] Furthermore, the first convex surface 122 is located around the top of the protrusion 120, smoothly transitioning to the sidewalls and top surface of the protrusion 120. The second convex surface 222 is located at the opening edge of the recess 220, smoothly transitioning to the inner wall of the recess 220. These two convex surface structures can coexist to form a hyperboloid guide system; alternatively, only one of them can be used to simplify the process steps. The connection between the first convex surface 122 and the second convex surface 222 and the structure is fixed and can be formed by controlling the sidewall morphology of the etching process, without the need for additional material deposition.

[0050] During the bonding process, when the first wafer 100 and the second wafer 200 approach each other, the protrusion 120 with the first convex surface 122 first contacts the recess 220. If the protrusion 120 has a slight tilt or offset, the first convex surface 122, as a curved surface, can reduce the impact force with the wall of the recess 220, avoiding jamming or damage. At the same time, the second convex surface 222, as a guiding curved surface at the entrance of the recess 220, provides a smooth guide path for the protrusion 120 to enter. After the protrusion 120 enters the recess 220, the convex structure can also play a role in stress dispersion, avoiding local stress concentration that could lead to microstructural fracture.

[0051] This embodiment optimizes the insertion performance of the limiting structure by providing a first convex surface 122 on the outer periphery of the protrusion 120 near the recess 220, or by providing a second convex surface 222 on the inner wall of the recess 220 near the protrusion 120. The curved surface design effectively eliminates the stress concentration and jamming risks caused by right-angle structures during mating. During the bonding process, these convex surface structures act as guides, allowing the protrusion 120 to slide into the recess 220 more smoothly and easily, reducing insertion resistance and avoiding impact damage to the precision microstructure. At the same time, the curved surface structure also provides better adaptability when the protrusion 120 and the recess 220 make inclined contact, further improving the stability and success rate of the bonding process.

[0052] Reference Figure 1 and Figure 2 In some embodiments of this application, both the first wafer 100 and the second wafer 200 are provided with bonding portions 130; at least one of the first wafer 100 and the second wafer 200 is provided with a baffle 140, which is located outside the bonding portion 130; during the bonding process, the baffle 140 abuts against the first wafer 100 or the second wafer 200 to prevent the molten bonding portion 130 from overflowing.

[0053] Specifically, the bonding portion 130 is a metallized region on the first wafer 100 and the second wafer 200 used to achieve a permanent connection. One of the two bonding portions 130 can be made of an aluminum-copper alloy, and the other can be made of germanium. The aluminum-copper alloy will soften and melt at a high temperature of 400°C. The barrier 140 is a barrier structure disposed on both sides of the bonding portion 130, and its material can be silicon oxide, formed by a vapor deposition process.

[0054] Furthermore, the barrier 140 is fixedly connected to the wafer it is attached to, and can be an integrally formed structure through deposition and etching processes. The barrier 140 can be disposed on the first wafer 100, the second wafer 200, or both the first wafer 100 and the second wafer 200 can be provided with barrier walls to form a double-barrier structure. The height of the barrier 140 needs to be precisely designed to meet the following relationship: the height of the barrier 140 is greater than the height of the bonding portion 130, but less than the sum of the heights of the two bonding portions 130. This ensures that during the bonding process, the barrier 140 can be fully compressed and contact the opposite wafer before the bonding portion 130, allowing the two corresponding bonding portions 130 to bond. In addition, the barrier 140 can be designed as a discontinuous, intermittent structure, composed of multiple spaced pillars.

[0055] During the bonding process, when pressure and temperature are applied to the stacked first wafer 100 and second wafer 200, the bonding portion 130 of the aluminum-copper alloy begins to soften and molten. As the pressure continues, the molten aluminum-copper alloy in the bonding area is squeezed and flows outwards. When it flows to the baffle 140, since the baffle 140 has already abutted against the surface of the opposite wafer, forming a barrier, the molten material cannot overflow beyond the baffle 140. The material is confined to the area inside the baffle 140 and solidifies as the temperature decreases, forming a complete and dense bonding sealing ring. The presence of the baffle 140 ensures that the bonding material does not contaminate other areas of the wafer.

[0056] Reference Figure 1 and Figure 2 In some embodiments of this application, the barrier 140 and the protrusion 120 are both located on the first wafer 100, or the barrier 140 and the protrusion 120 are both located on the second wafer 200. When the barrier 140 abuts against the first wafer 100 or the second wafer 200, the protrusion 120 abuts against the bottom end of the recess 220.

[0057] During use, when the first wafer 100 and the second wafer 200 approach each other under bonding pressure, the protrusion 120 first enters the recess 220. As the pressure increases, the barrier 140 on the first wafer 100 gradually approaches the surface of the second wafer 200. When the bonding pressure reaches a predetermined value, the top of the barrier 140 makes tight contact with the surface of the second wafer 200, preventing the first wafer 100 from moving further towards the second wafer 200. At the same time, the top of the protrusion 120 contacts the bottom of the recess 220. At this point, the first wafer 100 is supported vertically by both the barrier 140 and the protrusion 120, and constrained horizontally by the interaction between the protrusion 120 and the recess 220, forming a stable limiting state.

[0058] In this embodiment, by placing both the barrier 140 and the protrusion 120 on the first wafer 100 and precisely designing the matching relationship between their heights and the depth of the recess 220, the synchronous and synergistic effect of vertical support and horizontal limiting is achieved. At the moment bonding is completed, the barrier 140 abuts against the second wafer 200, effectively preventing the molten bonding portion 130 from overflowing and precisely controlling the bonding gap; simultaneously, the protrusion 120 abuts against the bottom end of the recess 220, providing an additional vertical support point for the bonding interface, forming a stable support structure. This synchronous design ensures that before the bonding material is completely cured, the first wafer 100 and the second wafer 200 are in a precisely limited state in both the vertical and horizontal directions, maximizing the alignment accuracy and packaging consistency of the final product.

[0059] In some embodiments of this application, there are multiple first limiting members, which are arranged at intervals along the circumference of the first bonding surface 110; there are multiple second limiting members, which are arranged at intervals along the circumference of the second bonding surface 210; the first limiting members and the second limiting members are provided in a one-to-one correspondence.

[0060] Specifically, multiple first limiting members are arranged at circumferential intervals along the first bonding surface 110, and multiple second limiting members are similarly arranged at circumferential intervals along the second bonding surface 210. The first and second limiting members are configured in a one-to-one correspondence, with each first limiting member having a paired second limiting member. For example, four first limiting members and four corresponding second limiting members can be arranged at 90-degree equidistant angles on a circular wafer to resist rotational displacement.

[0061] Furthermore, the distribution of multiple first limiting elements needs to be optimized based on the possible offset directions that may occur during the bonding process. If process monitoring data shows that the offset mainly occurs in a specific direction, such as the jig and gasket extraction direction, more densely packed limiting elements can be arranged in that direction. If the offset direction is uncertain, a uniform distribution can be used to provide all-around limiting protection. The one-to-one correspondence between the first and second limiting elements is achieved through precise alignment of the photolithography pattern. Before wafer bonding, the equipment adjusts the first wafer 100 and the second wafer 200 to the designed positions using alignment marks, ensuring that each first limiting element is located directly above or below its corresponding second limiting element.

[0062] During use, when the first wafer 100 and the second wafer 200 shift relative to each other due to the removal of the fixture and shims, the first limiting member located in front of the shift direction will first contact the corresponding second limiting member. This contact generates a blocking force, preventing the shift from continuing to expand. Since multiple limiting members are distributed circumferentially, regardless of the direction the wafer shifts, there will always be at least one pair of limiting members on the shift path providing obstruction. If the shift includes both translational and rotational components, multiple pairs of limiting members will be subjected to force simultaneously, forming a torque that resists rotation and stabilizes the wafer at the correct angular position.

[0063] This embodiment constructs a multi-point omnidirectional limiting system by setting multiple first limiting members and corresponding second limiting members arranged at circumferential intervals. Compared with a single limiting structure, the multi-point layout can more effectively resist offset forces from different directions and resist wafer rotational offset. When a torsional tendency occurs, the limiting members located at different positions are simultaneously subjected to forces in different directions, working together to form a resisting torque, stabilizing the first wafer 100 and the second wafer 200 at the correct angular positions. This design significantly enhances the sensor's ability to resist complex offsets, including translational and rotational offsets, further improving the robustness of bonding alignment and product yield.

[0064] In other possible embodiments, the multiple first limiting elements can employ a non-uniform distribution strategy to adapt to specific process requirements. For example, depending on the direction of jig and spacer extraction in the bonding process, a higher density of limiting elements can be arranged at the wafer edge corresponding to the extraction direction, while a lower density of limiting elements can be arranged on the opposite side. Alternatively, limiting elements can be arranged at unequal angular intervals on the wafer circumference, so that the position of the limiting elements matches the chip layout and avoids sensitive areas on the chip. The advantage of this non-uniform distribution is that it can provide stronger limiting protection in critical directions while saving wafer area in non-critical directions, achieving an optimized balance between limiting effect and area occupation. For example, for processes with a high risk of jig and spacer extraction direction misalignment, three limiting elements can be set in that direction, while one element can be set in each of the other directions.

[0065] In some embodiments of this application, the first limiting member is disposed on the first wafer 100 by deposition and etching, and the second limiting member is disposed on the second wafer 200 by deposition and etching.

[0066] Specifically, deposition refers to forming a thin film material on the surface of a wafer through methods such as chemical vapor deposition or physical vapor deposition. Etching refers to selectively removing part of the thin film material through chemical or physical processes, while retaining the desired pattern structure. In this embodiment, the first limiting member is formed by first depositing an aluminum-copper alloy thin film on a first silicon wafer 100, and then etching the aluminum-copper alloy thin film into shape using photolithography and etching processes. Similarly, the second limiting member is formed by first depositing an oxide thin film (specifically, a silicon dioxide thin film) on a second silicon wafer 200, and then processing the silicon dioxide thin film into the desired shape using photolithography and etching processes.

[0067] In this embodiment, a first limiting member is deposited on a first wafer 100 and a second limiting member is deposited on a second wafer 200 using deposition and etching, achieving heterogeneous material integration between the limiting structure and the wafer substrate. The deposited silicon dioxide limiting member features high hardness, good wear resistance, and strong adhesion to the silicon substrate, providing reliable limiting during bonding. Furthermore, the deposition and etching processes are fully compatible with standard semiconductor processes and can be directly implemented on existing production lines without additional equipment investment.

[0068] In other possible embodiments, the first and second limiting elements can be formed using other deposition materials. For example, materials such as silicon nitride, polycrystalline silicon, or silicon carbide can be deposited and etched to form the limiting structure. Silicon nitride has higher hardness and better wear resistance, making it suitable for processes with many bonding cycles or high bonding pressure. Polycrystalline silicon has the same coefficient of thermal expansion as the silicon substrate, which better avoids thermal stress problems. Silicon carbide has extremely high hardness and chemical stability.

[0069] Reference Figure 5 and Figure 7 In some embodiments of this application, the first limiting member and the second limiting member limit each other in the circumferential and / or radial directions.

[0070] Specifically, mutual restraint in the circumferential direction refers to restricting the relative rotational movement of the first wafer 100 and the second wafer 200 around an axis perpendicular to the bonding surface. Mutual restraint in the radial direction refers to restricting the relative translational movement of the two wafers in a plane parallel to the bonding surface.

[0071] In one specific embodiment (see reference) Figure 7The first limiting member can be designed as a frustum-shaped structure, with a larger dimension at the end connected to the first wafer 100 and a smaller dimension at the end that engages with the second limiting member. The second limiting member can be another frustum-shaped cylindrical structure, with a frustum-shaped groove inside the cylinder that matches the shape of the first limiting member. This fit is similar to the fit between a shaft and a hole, with the frustum-shaped first limiting member and the frustum-shaped groove nested together. When circumferential limiting is required, at least two sets of the first and second limiting members in this embodiment are needed.

[0072] In another specific embodiment (see reference) Figure 5 The first limiting member retains the same frustum-shaped structure. The second limiting member consists of two spaced-apart limiting blocks 223, forming a groove between them. The shape of this groove matches the shape of the first limiting member. In this configuration, after the frustum-shaped first limiting member enters the groove between the two limiting blocks 223, its sidewall contacts the inner wall of the two limiting blocks 223, thus restricting translational movement in a specific direction and achieving radial limiting.

[0073] In some embodiments of this application, the preset range (i.e., x) is greater than or equal to 0 micrometers and less than or equal to 10 micrometers.

[0074] Specifically, the preset range refers to the maximum permissible offset between the first wafer 100 and the second wafer 200 that can be guaranteed after the first and second limiting members cooperate with each other (i.e., after bonding is completed). The upper limit of this range is 10 micrometers, and the lower limit is 0 micrometers. 0 micrometers represents the ideal state of perfect alignment, and 10 micrometers represents the maximum permissible deviation.

[0075] Furthermore, the specific value of the preset range is determined by the mating gap between the first limiting member and the second limiting member, that is, by x in the above embodiment. If the minimum gap between the outer wall of the protrusion 120 and the inner wall of the recess 220 is 7 micrometers, then the maximum allowable gap between the bottom of the first limiting member and the top of the second limiting member after bonding is 7 micrometers. It should be noted that the value of the preset range can be determined comprehensively based on factors such as the process node, chip size, and performance requirements of the specific product. For high-precision MEMS devices such as inertial measurement units, the bonding alignment error is required to be less than 5 micrometers, so the preset range can be set to 0 to 5 micrometers.

[0076] This embodiment, by explicitly limiting the preset range to greater than or equal to 0 micrometers and less than or equal to 10 micrometers, can effectively reduce and control uncontrollable offsets within a controllable range of less than 10 micrometers. This directly corresponds to a significant improvement in bonding accuracy and a reduction in the risk of product failure.

[0077] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0078] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A sensor, characterized by include: A first wafer (100) has a first bonding surface (110) and a first limiting member is provided on the first bonding surface (110); The second wafer (200) has a second bonding surface (210) opposite to the first bonding surface (110), and the second bonding surface (210) is provided with a second limiting member; During the bonding process between the first wafer (100) and the second wafer (200), the first limiting member and the second limiting member limit each other to limit the offset distance between the first wafer (100) and the second wafer (200) after bonding is completed within a preset range.

2. The sensor of claim 1, wherein, One of the first limiting member and the second limiting member has a protrusion (120), and the other of the first limiting member and the second limiting member has a recess (220). The protrusion (120) and the recess (220) are adapted to each other in shape. During the bonding process, the protrusion (120) extends into the interior of the recess (220), and the outer wall of the protrusion (120) abuts against the inner wall of the recess (220) to guide the first wafer (100) and the second wafer.

3. The sensor of claim 2, wherein, The outer wall of the protrusion (120) is provided with a first guide slope (121), and the inner wall of the recess (220) is provided with a second guide slope (221). During the bonding process, the first guide slope (121) and the second guide slope (221) abut against each other to guide the first wafer (100) and the second wafer.

4. The sensor of claim 3, wherein, The protrusion (120) has a first convex surface (122) at one end near the recess (220), and / or the recess (220) has a second convex surface (222) at one end near the protrusion (120).

5. The sensor of claim 2, wherein, Both the first wafer (100) and the second wafer (200) are provided with bonding portions (130); At least one of the first wafer (100) and the second wafer (200) is provided with a barrier (140), the barrier (140) being located outside the bonding portion (130); During the bonding process, the barrier (140) abuts against the first wafer (100) or the second wafer (200) to prevent the molten bonding portion (130) from overflowing.

6. The sensor of claim 5, wherein, The barrier (140) and the protrusion (120) are both located on the first wafer (100), or the barrier (140) and the protrusion (120) are both located on the second wafer (200). When the barrier (140) abuts against the first wafer (100) or the second wafer (200), the protrusion (120) abuts against the bottom end of the recess (220).

7. The sensor of any one of claims 1-6, wherein, There are multiple first limiting members, and the multiple first limiting members are arranged at intervals along the circumference of the first bonding surface (110); There are multiple second limiting members, and the multiple second limiting members are arranged at intervals along the circumference of the second bonding surface (210); The first limiting member and the second limiting member are set in a one-to-one correspondence.

8. The sensor of any one of claims 1-6, wherein, The first limiting member is disposed on the first wafer (100) by deposition and etching, and the second limiting member is disposed on the second wafer (200) by deposition and etching.

9. The sensor according to any one of claims 1-6, characterized in that, The first limiting member and the second limiting member limit each other in the circumferential and / or radial directions.

10. The sensor according to any one of claims 1-6, characterized in that, The preset range is greater than or equal to 0 micrometers and less than or equal to 10 micrometers.

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