Substrate wafer structure and MEMS device package structure
Patent Information
- Application Number
- CN202522306752.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-30
- Publication Date
- 2026-09-11
- Estimated Expiration
- 2035-10-30
AI Technical Summary
[0006]本实用新型的目的在于提供一种基底晶圆结构及MEMS器件封装结构，解决键合过程中金属溢流的问题
[0021]本实用新型在基底晶圆上表面的第一金属键合环的内侧设置环形的内侧挡坝，并将内侧挡坝结构顶部的转角设计为倒角结构，采用该挡坝结构能够在后续将该基底晶圆结构与MEMS器件晶圆通过金属键合环进行共晶键合时，借助该内侧挡坝结构阻挡共晶合金向MEMS器件核心功能区溢流，避免核心功能失效，同时通过内侧挡坝顶部倒角避免键合对位过程中挡坝与MEMS器件晶圆发生碰撞产生碎屑的问题，提高器件的可靠性，最终可实现防溢流、无碎屑风险且高可靠性的MEMS器件制备，有效解决了传统有挡坝方案仍存在的金属溢流问题。
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Figure CN224740828U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor device manufacturing, and in particular to a substrate wafer structure and a MEMS device packaging structure. Background Technology
[0002] MEMS (Micro-Electro-Mechanical Systems) devices, with their core advantages of miniaturization, integration, and low power consumption, have been widely used in consumer electronics (such as inertial sensors), automotive electronics (such as pressure sensors), and industrial control (such as micro-actuators). In the packaging and fabrication of MEMS devices, wafer bonding is the core step in achieving device sealing, structural fixation, and functional isolation. Among these, eutectic bonding, due to its high sealing reliability, low interface impedance, and excellent long-term stability, has become the mainstream bonding solution for metal-based MEMS devices (such as devices with electrode leads and signal transmission structures).
[0003] Eutectic bonding relies on bonding rings on both the MEMS wafer and the sub-wafer. These two bonding rings are made of different metals (such as Al-Ge or Ni-Sn eutectic metal combinations). Under predetermined temperature and pressure, the two metal bonding rings form a low-melting-point eutectic alloy, thus achieving a tight bond between the wafers. However, eutectic bonding carries the risk of metal overflow. If the molten eutectic alloy diffuses into the core functional areas of the MEMS wafer (such as the sensing element of a microsensor or the drive structure of a microactuator), it can cause short circuits, sensitivity degradation, or functional failure in core components.
[0004] To address the metal overflow issue, the industry has primarily developed two technical approaches: damless and dammed solutions. The damless approach involves not placing any obstruction structures around the bonding ring, suppressing overflow solely through precise control of the eutectic temperature, pressure, and bonding ring metal layer thickness. However, this approach requires minimizing metal overflow, resulting in a very small process window and extremely high precision requirements for process parameters. Furthermore, it lacks a physical limiting reference during bonding alignment, making it difficult to meet high-yield production demands. The dammed approach, on the other hand, adds a dam structure around the bonding ring, typically a ring-shaped dam on the outer side of the bonding ring (closer to the wafer edge). This provides physical restraint during bonding alignment and blocks some of the overflow.
[0005] However, the existing dam structure design still results in a relatively serious metal overflow problem for the device. Utility Model Content
[0006] The purpose of this invention is to provide a substrate wafer structure and a MEMS device packaging structure to solve the problem of metal overflow during bonding.
[0007] To achieve the above objectives, in a first aspect, this utility model proposes a substrate wafer structure, comprising:
[0008] Substrate wafer;
[0009] A first metal bonding ring is disposed on the upper surface of the substrate wafer;
[0010] An annular inner dam structure is disposed on the upper surface of the substrate wafer and located inside the first metal bonding ring. The first metal bonding ring surrounds the inner dam structure, and the top corner of the inner dam structure is chamfered.
[0011] Optionally, it also includes an annular outer dam structure, which is disposed on the upper surface of the substrate wafer and located outside the first metal bonding ring. The outer dam structure surrounds the first metal bonding ring, and the top corner of the outer dam structure is chamfered.
[0012] Optionally, the height of the inner retaining dam structure is greater than the height of the first metal bonding ring, and the height of the outer retaining dam structure is the same as the height of the inner retaining dam structure.
[0013] Optionally, the inner retaining dam structure and / or the outer retaining dam structure are made of silicon oxide or silicon nitride.
[0014] Optionally, the chamfer at the top of the inner retaining dam structure and / or the outer retaining dam structure is formed by a dry etching process.
[0015] Optionally, the upper surface of the substrate wafer is provided with an insulating layer, and a redistribution layer is provided within the insulating layer. The first metal bonding ring is disposed on the insulating layer and connected to the redistribution layer.
[0016] Secondly, this utility model also proposes a MEMS device packaging structure, including a substrate wafer structure, a device wafer and a cap wafer arranged sequentially from bottom to top;
[0017] The substrate wafer structure is the substrate wafer structure described in the first aspect;
[0018] The device wafer has a MEMS functional area, and the lower surface of the device wafer has a second metal bonding ring. The second metal bonding ring is opposite to and bonded to the first metal bonding ring. The projection of the inner dam structure on the surface of the device wafer is located between the MEMS functional area and the second metal bonding ring.
[0019] The lower surface of the cap wafer has a cavity, the upper surface of the device wafer is bonded to the lower surface of the cap wafer, and the MEMS functional area corresponds to the cavity.
[0020] The beneficial effects of this utility model are as follows:
[0021] This invention features an annular inner dam on the inner side of the first metal bonding ring on the surface of the substrate wafer. The top corner of the inner dam structure is designed as a chamfer. This dam structure prevents the eutectic alloy from overflowing into the core functional area of the MEMS device during subsequent eutectic bonding of the substrate wafer structure and the MEMS device wafer via the metal bonding ring, thus avoiding core function failure. At the same time, the chamfer at the top of the inner dam prevents collisions between the dam and the MEMS device wafer during bonding alignment, thus improving device reliability. Ultimately, this invention enables the fabrication of MEMS devices that are overflow-proof, debris-free, and highly reliable, effectively solving the metal overflow problem that still exists in traditional dam-based solutions. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of a substrate wafer structure according to Embodiment 1 of this utility model.
[0024] Figure 2 This is a schematic diagram of another substrate wafer structure according to Embodiment 1 of this utility model.
[0025] Figure 3 This is a schematic diagram of a MEMS device packaging structure according to Embodiment 2 of this utility model.
[0026] Figure 4 , Figure 5 This is a device structure diagram corresponding to some steps in the fabrication process of a MEMS device packaging structure according to Embodiment 2 of this utility model. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and drawings. However, it should be noted that the concept of the present invention can be implemented in many different forms and is not limited to the specific embodiments described herein. The drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.
[0028] The terms “first,” “second,” etc., used in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological sequence. It should be understood that these terms, used so in this way, may be replaced where appropriate, for example, to allow embodiments of the invention described herein to operate in a different order than that described or shown herein. Similarly, if the methods described herein comprise a series of steps, and the order of these steps presented herein is not necessarily the only possible order in which these steps can be performed, and some described steps may be omitted and / or some other steps not described herein may be added to the method. If a component in one figure is identical to a component in another figure, although these components are readily identifiable in all figures, this specification will not label all identical components in every figure for the sake of clarity.
[0029] Example 1
[0030] like Figure 1 As shown, this embodiment provides a substrate wafer structure, including:
[0031] Substrate wafer 1;
[0032] A first metal bonding ring 2 is disposed on the upper surface of the substrate wafer 1;
[0033] An annular inner dam structure 3 is disposed on the upper surface of the substrate wafer 1 and located inside the first metal bonding ring 2. The first metal bonding ring 2 surrounds the inner dam structure 3, and the top corner of the inner dam structure 3 is chamfered.
[0034] In this embodiment, an insulating layer 5 is further disposed on the substrate wafer 1, and a redistribution layer 6 is disposed within the insulating layer 5. The first metal bonding ring 2 is disposed on the insulating layer 5 and connected to the redistribution layer 6.
[0035] Optionally, such as Figure 2 As shown, the substrate wafer 1 structure in this embodiment also includes an annular outer dam structure 4. The outer dam structure 4 is disposed on the upper surface of the substrate wafer 1 and located outside the first metal bonding ring 2. The outer dam structure 4 surrounds the first metal bonding ring 2, and the top corner of the outer dam structure 4 is chamfered.
[0036] It is understood that annular dams are respectively set on the inner side (the side closer to the core functional area) and the outer side (the side closer to the wafer edge) of the first metal bonding ring 2. The outer dam can physically limit the bonding alignment and block some overflow, while the inner dam can limit the molten metal while preventing it from overflowing into the core functional area. In addition, during the dam fabrication process, dielectric layer deposition and patterning processes are usually used to form the dam structure, which will form a sharp shoulder at the top corner of the dam (i.e., the dam structure presents a stepped structure with sharp edges). During the subsequent wafer bonding alignment process, this sharp shoulder is prone to mechanical collision with the surface structure of adjacent wafers, causing dielectric layer debris to fall off the dam. In particular, the debris falling off the inner dam can adhere to the core functional area of the MEMS wafer or embed into the eutectic bonding interface, causing device reliability problems. Therefore, in this embodiment, the top corners of the inner dam structure 3 and / or the outer dam structure 4 are set as chamfers, which can effectively solve the debris problem and improve device reliability.
[0037] In this embodiment, the height of the inner dam structure 3 is greater than the height of the first metal bonding ring 2, and the height of the outer dam structure 4 is the same as the height of the inner dam structure 3. The inner dam structure 3 and / or the outer dam structure 4 are made of silicon oxide or silicon nitride.
[0038] The chamfers at the top of the inner retaining dam structure 3 and / or the outer retaining dam structure 4 are formed by a dry etching process.
[0039] Specifically, a dielectric layer can be deposited on the side of the first metal bonding ring 2 on the substrate wafer 1; then, patterned photoresist can be formed on the dielectric layer to define the annular inner dam structure 3 region and / or outer dam structure 4 region; then, the dielectric layer can be etched using the patterned photoresist as a mask to form the annular inner dam structure 3 and outer dam structure 4 on the inner side of the first metal bonding ring 2, and then the substrate wafer 1 can be cleaned. Since the top of the inner dam structure 3 and outer dam structure 4 formed by the deposition of the dielectric layer and the photolithography process is a sharp corner (the cross-section perpendicular to the surface of the substrate wafer 1 is rectangular, and the corner is about 90°), this embodiment uses a process gas that only reacts with the dam structure material to etch the front side of the substrate wafer 1 through a dry etching process, so that the sharp corners of the inner and outer sides of the top of the inner dam structure 3 and outer dam structure 4 are transformed into rounded chamfers.
[0040] Example 2
[0041] like Figure 3 As shown, this embodiment provides a MEMS device packaging structure, including a substrate wafer structure, a device wafer 7, and a cap wafer 8 arranged sequentially from bottom to top;
[0042] The substrate wafer structure is the substrate wafer structure described in Example 1;
[0043] The device wafer 7 has a MEMS functional area 10 (shown by the dashed box in the figure), and a second metal bonding ring 9 is provided on the lower surface of the device wafer 7. The second metal bonding ring 9 is opposite to and bonded to the first metal bonding ring 2. The projection of the inner dam structure 3 on the surface of the device wafer 7 is located between the MEMS functional area 10 and the second metal bonding ring 9.
[0044] The lower surface of the cap wafer 8 is provided with a cavity, the upper surface of the device wafer 7 is bonded to the lower surface of the cap wafer 8, and the MEMS functional area 10 corresponds to the position of the cavity.
[0045] The fabrication process of a MEMS device packaging structure in this embodiment is as follows:
[0046] like Figure 4 As shown, a substrate wafer 1 is provided, and a first metal bonding ring 2 is provided on the front side of the substrate wafer 1;
[0047] The substrate wafer 1 has an insulating layer 5 on its upper surface, a redistribution layer 6 within the insulating layer 5, and a first metal bonding ring 2 disposed on the insulating layer 5 and connected to the redistribution layer 6. The insulating layer 5 is made of silicon oxide or silicon nitride.
[0048] like Figure 5 As shown, on the upper surface of the substrate wafer 1, an annular inner dam structure 3 is formed inside the first metal bonding ring 2, and the top of the inner dam structure 3 is higher than the top of the first metal bonding ring 2; optionally, while forming the annular inner dam structure 3 inside the first metal bonding ring 2, an annular outer dam structure 4 is also formed outside the first metal bonding ring 2, and the height of the outer dam structure 4 is the same as the height of the inner dam structure 3.
[0049] The inner retaining dam structure 3 and the outer retaining dam structure 4 can be made of silicon oxide or silicon nitride. In this embodiment, silicon oxide is selected.
[0050] The method for forming the annular inner retaining dam structure 3 and outer retaining dam 4 in this step includes:
[0051] A dielectric layer is deposited on one side of the substrate wafer 1 where the first metal bonding ring 2 is provided. The dielectric layer is made of silicon oxide.
[0052] Patterned photoresist is formed on the dielectric layer to define the area where the inner ring-shaped dam structure 3 and the outer ring-shaped dam structure 4 are located;
[0053] Using patterned photoresist as a mask to etch the dielectric layer, an annular inner dam structure 3 and an outer dam structure 4 are simultaneously formed on the inner and outer sides of the first metal bonding ring 2.
[0054] After forming the inner dam structure 3 and the outer dam structure 4 in the etching medium layer, the upper surface of the substrate wafer 1 is also cleaned.
[0055] After the inner retaining dam structure 3 and / or the outer retaining dam structure 4 are initially formed, the inner retaining dam structure 3 and / or the outer retaining dam structure 4 can be chamfered to transform the sharp corners at the top of the inner retaining dam structure 3 and the outer retaining dam structure 4 into rounded corners (e.g., Figure 1 (or as shown in Figure 2);
[0056] Specifically, a process gas that reacts only with the material (silicon oxide) of the inner dam structure 3 and the outer dam structure 4 is used to etch the front side of the substrate wafer 1 through a dry etching process, so that the sharp corners on the inner and outer sides of the top of the inner dam structure 3 and the outer dam structure 4 are transformed into rounded corners.
[0057] In one example, the inner dam structure 3 and the outer dam structure 4 are made of silicon oxide. A fluorocarbon process gas, such as CF4, which reacts only with silicon oxide, can be used to etch the entire front side of the substrate wafer 1 using ICP (Inductively Coupled Plasma) etching. Utilizing the high etchability of the fluorocarbon process gas to silicon oxide, isotropic etching of the inner dam structure 3 and the outer dam structure 4 is achieved with a low bias voltage. This etches away the sharp corners at the top of the inner dam structure 3 and the outer dam structure 4, creating rounded chamfers. The rounded chamfers at the top of the inner dam structure 3 and the outer dam structure 4 prevent collisions with adjacent wafers during subsequent bonding and alignment, thus avoiding debris problems.
[0058] After etching the front side of substrate wafer 1, the front side of substrate wafer 1 also needs to be cleaned to remove etching byproducts.
[0059] refer to Figure 3 This embodiment also provides a device wafer 7 and a cap wafer 8. The device wafer 7 has a MEMS functional area 10 (comb structure). The lower surface of the cap wafer 8 has a cavity. The upper surface of the device wafer 7 is bonded to the lower surface of the cap wafer 8. The MEMS functional area 10 corresponds to the cavity. A second metal bonding ring 9 is disposed on the lower surface of the device wafer 7. The first metal bonding ring 2 and the second metal bonding ring 9 are made of different metal materials, such as Ni-Sn, Au-In, Al-Ge, etc. For example, in this embodiment, the material of the first metal bonding ring 2 is Al, and the material of the second metal bonding ring 9 is Ge.
[0060] The lower surface of the device wafer 7 is aligned with the upper surface of the substrate wafer 1, and the projections of the second metal bonding ring 9 and the first metal bonding ring 2 on the upper surface of the substrate wafer overlap, and the projection of the inner dam structure 3 on the lower surface of the device wafer 7 is located between the second metal bonding ring 9 and the MEMS device functional area 10.
[0061] The first metal bonding ring 2 and the second metal bonding ring 9 are bonded together using a eutectic bonding process.
[0062] When eutectic bonding the first metal bonding ring 2 and the second metal bonding ring 9, the inner dam structure 3 prevents metal from overflowing into the core functional area of the MEMS device, thus avoiding core function failure. Simultaneously, the rounded corner at the top of the inner dam structure 3 prevents collisions between the top of the dam and the bottom of the device wafer 7 or the second metal bonding ring 9 during the bonding alignment process, avoiding debris entering the MEMS functional area 10 due to collisions and improving device reliability. The outer dam structure 4 provides restraint and prevents metal overflow from the eutectic bonding to the periphery of the chip area, ultimately achieving overflow-proof, debris-free, and highly reliable MEMS device fabrication, effectively solving the metal overflow problem present in devices using traditional dam solutions.
[0063] It should be noted that the various embodiments in this specification are described in a related manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for structural embodiments, since they are basically similar to method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments.
[0064] The above description is only a description of the preferred embodiment of the present utility model and is not intended to limit the scope of the present utility model in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.
Claims
1. A substrate wafer structure, characterized by, include: Substrate wafer; A first metal bonding ring is disposed on the upper surface of the substrate wafer; An annular inner dam structure is disposed on the upper surface of the substrate wafer and located inside the first metal bonding ring. The first metal bonding ring surrounds the inner dam structure, and the top corner of the inner dam structure is chamfered.
2. The base wafer structure of claim 1, wherein It also includes an annular outer dam structure, which is disposed on the upper surface of the substrate wafer and located outside the first metal bonding ring. The outer dam structure surrounds the first metal bonding ring, and the top corner of the outer dam structure is chamfered.
3. The base wafer structure of claim 2, wherein, The height of the inner retaining dam structure is greater than the height of the first metal bonding ring, and the height of the outer retaining dam structure is the same as the height of the inner retaining dam structure.
4. The base wafer structure of claim 2, wherein The inner retaining dam structure and / or the outer retaining dam structure are made of silicon oxide or silicon nitride.
5. The base wafer structure of claim 2, wherein The chamfers at the top of the inner retaining dam structure and / or the outer retaining dam structure are formed by a dry etching process.
6. The base wafer structure of claim 1, wherein An insulating layer is provided on the upper surface of the substrate wafer, and a redistribution layer is provided within the insulating layer. The first metal bonding ring is disposed on the insulating layer and connected to the redistribution layer.
7. A MEMS device package structure, characterized by, It includes, from bottom to top, the substrate wafer structure, the device wafer, and the cap wafer; The substrate wafer structure is the substrate wafer structure as described in any one of claims 1-6; The device wafer has a MEMS functional area, and the lower surface of the device wafer has a second metal bonding ring. The second metal bonding ring is opposite to and bonded to the first metal bonding ring. The projection of the inner dam structure on the surface of the device wafer is located between the MEMS functional area and the second metal bonding ring. The lower surface of the cap wafer has a cavity, the upper surface of the device wafer is bonded to the lower surface of the cap wafer, and the MEMS functional area corresponds to the cavity.