MEMS wafer bonding unsealing method

Abstract

The application provides a MEMS wafer bonding opening method, and relates to the field of MEMS, which comprises the following steps: removing a plastic package of a first MEMS sample, and removing a bonding wire between an ASIC and the MEMS sample to obtain a second MEMS sample; placing the second MEMS sample in anhydrous ethylenediamine at room temperature or under heating to soak until the ASIC and the MEMS sample are separated to obtain a third MEMS sample; taking the third MEMS sample out of the anhydrous ethylenediamine at room temperature or under heating, and rinsing the third MEMS sample in a way other than ultrasonic to obtain a fourth MEMS sample; heating a MEMS wafer sealed in the fourth MEMS sample, and vertically separating the MEMS wafer and a MEMS sealing cover to perform MEMS wafer bonding opening.

Description

Technical Field

[0001] This application relates to the field of MEMS technology, and in particular to a method for opening MEMS wafer bonding. Background Technology

[0002] Micro-Electro-Mechanical Systems (MEMS), also known as micro-electromechanical systems, microsystems, or micromechanical devices, refer to high-tech devices with dimensions of a few millimeters or even smaller. MEMS devices generally have movable parts or suspended structures that sense external signals, such as thin films or microbeams. Most components also have Si cup cavities or high aspect ratio three-dimensional structures. These movable parts and three-dimensional structures require sufficiently large cavities as movement space, while also needing to prevent dust accumulation. To meet these requirements, wafer bonding is used. There are many wafer bonding methods, mainly including anodic bonding, direct Si bonding, glass bonding, eutectic bonding, thermocompression bonding, and adhesive bonding.

[0003] Currently, MEMS requires unpacking when samples need to undergo failure analysis, composition analysis, or materials analysis. However, there is no ideal method for unpacking MEMS. Most laboratories currently use grinding, forceful pulling, or physical tapping methods to unpack MEMS. Since MEMS devices are mostly three-dimensional and suspended structures, grinding can damage the internal components, while forceful pulling or physical tapping can cause the chip to shatter if not handled properly. Summary of the Invention

[0004] The purpose of this application is to provide a MEMS wafer bonding unpacking method to solve the technical problem that current MEMS unpacking methods are prone to device damage.

[0005] In a first aspect, this application provides a method for opening a MEMS wafer bond, the method comprising: The encapsulation of the first MEMS sample is removed, and the bonding lines between the ASIC and the MEMS sample are removed to obtain the second MEMS sample. The second MEMS sample is immersed in anhydrous ethylenediamine at room temperature or under heat until the ASIC separates from the MEMS sample, thus obtaining the third MEMS sample. The third MEMS sample is removed from anhydrous ethylenediamine at room temperature or heated, and then rinsed by a method other than ultrasound to obtain the fourth MEMS sample. The MEMS wafer in the fourth MEMS sample is heated, and the MEMS wafer and the MEMS sealing cover are vertically separated to perform MEMS wafer bonding unsealing.

[0006] In one possible implementation, removing the encapsulation from the first MEMS sample includes: The encapsulation of the first MEMS sample was completely removed by immersion in nitric acid at room temperature or by heating.

[0007] In one possible implementation, rinsing the third MEMS sample by a method other than ultrasound includes: The third MEMS sample was rinsed with sulfuric acid, water, acetone or anhydrous ethanol.

[0008] In one possible implementation, heating the encapsulated MEMS wafer in the fourth MEMS sample includes: The encapsulated MEMS wafer in the fourth MEMS sample is placed in a heating furnace that has been heated to a specified temperature and heated for a specified time.

[0009] In one possible implementation, the specified temperature is between 400 and 500 degrees.

[0010] In one possible implementation, the specified duration is between three and five minutes.

[0011] In one possible implementation, the vertical separation between the MEMS wafer and the MEMS cap includes: The MEMS wafer and the MEMS cover are separated by using two iron-tipped tweezers through a vertical clamping action, wherein one of the two iron-tipped tweezers is clamped on the MEMS wafer and the other iron-tipped tweezers is clamped on the MEMS cover; If the MEMS sealing cap cannot be removed, continue heating the sealed MEMS wafer and clamp it again.

[0012] In one possible implementation, before removing the molding compound of the first MEMS sample and the bonding lines between the ASIC and the MEMS sample to obtain the second MEMS sample, the method further includes: X-rays are used to determine the internal structure of the MEMS, whether the package contains a MEMS chip, and whether the chip has a substrate. If the substrate is present, it is first ground off before the die is obtained.

[0013] In one possible implementation, after the vertical separation between the MEMS wafer and the MEMS cap for MEMS wafer bonding unpacking, the process further includes: Optical microscopes are used to determine internal failure points or obtain internal structural information of MEMS, so as to observe the internal structure of MEMS and the MEMS silicon cap during the opening process of MEMS.

[0014] In one possible implementation, the specified temperature is a temperature obtained by adjusting the material and temperature data during MEMS bonding.

[0015] This application brings the following beneficial effects: This application provides a MEMS wafer bonding and unpacking method, which removes the molding compound of a first MEMS sample and the bonding lines between the ASIC and the MEMS sample to obtain a second MEMS sample; the second MEMS sample is immersed in anhydrous ethylenediamine at room temperature or with heating until the ASIC separates from the MEMS sample to obtain a third MEMS sample; the third MEMS sample is removed from the anhydrous ethylenediamine at room temperature or with heating and rinsed by a method other than ultrasonication to obtain a fourth MEMS sample; the MEMS wafer bonded in the fourth MEMS sample is heated, and the bonding lines between the ASIC and the MEMS wafer are simultaneously removed. The EMS wafer and MEMS cap are vertically separated for MEMS wafer bonding and unpacking. In this solution, high-temperature unpacking is used. That is, when unpacking the MEMS, various data such as the material and temperature during MEMS bonding are used to adjust the temperature for unpacking. Therefore, there is no need to use grinding, force pulling, or knife knocking methods to unpack the MEMS, thus avoiding damage to the internal devices of the MEMS such as chip breakage. The process of adjusting the temperature for unpacking using various data such as the material and temperature during MEMS bonding can also avoid device damage, alleviating the technical problem that current MEMS unpacking methods are prone to device damage.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic flowchart of the MEMS wafer bonding and unpacking method provided in the embodiments of this application; Figure 2 This is a schematic diagram of x-rays in the MEMS wafer bonding and unpacking method provided in the embodiments of this application; Figure 3 This is a schematic diagram of the die removal process in the MEMS wafer bonding and unpacking method provided in the embodiments of this application; Figure 4 This is a schematic diagram of the side after the ASIC and MEMS are separated in the MEMS wafer bonding and unpacking method provided in the embodiments of this application; Figure 5 A schematic diagram of the other side after the ASIC and MEMS are separated in the MEMS wafer bonding and unpacking method provided in the embodiments of this application; Figures 6(a) and 6(b) are schematic diagrams of the MEMS wafer bonding and unpacking method provided in the embodiments of this application, including the MEMS internal structure and the MEMS silicon cap, and the MEMS unpacking effect. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this application, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0021] Currently, MEMS requires unpacking when samples need to undergo failure analysis, composition analysis, or materials analysis. However, there is no ideal method for unpacking MEMS. Most laboratories currently use grinding, forceful pulling, or physical tapping methods to unpack MEMS. Since MEMS devices are mostly three-dimensional and suspended structures, grinding can damage the internal components, while forceful pulling and physical tapping can cause the chip to shatter.

[0022] Based on this, this application provides a MEMS wafer bonding unpacking method, which can solve the technical problem that current MEMS unpacking methods are prone to device damage.

[0023] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic flowchart illustrating a MEMS wafer bonding and unpacking method provided in an embodiment of this application. Figure 1 As shown, the method includes: In step S110, the encapsulation of the first MEMS sample is removed, and the bonding lines between the ASIC and the MEMS sample are removed to obtain the second MEMS sample.

[0025] Optional, such as Figure 2 As shown, before unpacking the sample, X-rays can be used to observe the internal condition of the MEMS, whether the package contains a MEMS encapsulated chip, and whether the chip has a substrate. If a substrate is present, it should be removed before obtaining the die. During the removal of the package, the sample can be completely removed by immersion in nitric acid at room temperature or by heating. Then, the sample can be removed to remove the bonding wires between the application-specific integrated circuit (ASIC) die and the MEMS die.

[0026] Step S120: Immerse the second MEMS sample in anhydrous ethylenediamine at room temperature or under heating until the ASIC separates from the MEMS sample to obtain the third MEMS sample.

[0027] In practical applications, after removing the leads between the ASIC and MEMS, the sample is immersed in fuming nitric acid at room temperature or heated anhydrous ethylenediamine until the ASIC and MEMS separate.

[0028] In step S130, the third MEMS sample is removed from anhydrous ethylenediamine at room temperature or under heating, and the third MEMS sample is rinsed by a method other than ultrasound to obtain the fourth MEMS sample.

[0029] For the IC cleaning process, the sample can be taken out after the ASIC and MEMS are separated. After taking it out, it can be rinsed with water, acetone or anhydrous ethanol. MEMS dies can be cleaned by methods other than ultrasonic cleaning.

[0030] In step S140, the encapsulated MEMS wafer in the fourth MEMS sample is heated, and the MEMS wafer and the MEMS encapsulation cover are vertically separated to perform MEMS wafer bonding unpacking.

[0031] For a schematic diagram of taking a MEMS die, such as Figure 3 As shown. For example, during the opening of the MEMS, the furnace is first heated to 400-500°C. Then, the sealed MEMS die is placed on the furnace and heated for three to five minutes. Two pointed iron tweezers are used, one clamping the MEMS die and the other clamping the MEMS sealing cap, and then lifted vertically. If the MEMS sealing cap cannot be removed, heating continues or the temperature is increased again, and then it is lifted again. A schematic diagram of the two sides after the ASIC and MEMS are separated is shown below. Figure 4 and Figure 5 As shown.

[0032] Optionally, after unpacking, an optical microscope can be used to observe the internal failure points of the MEMS or obtain internal structural information. As shown in Figures 6(a) and 6(b), the internal structure of the MEMS and the MEMS silicon cap can be observed in the unpacking results.

[0033] In this embodiment, high-temperature unpacking is employed. This involves adjusting the temperature during MEMS unpacking using various data, such as the material and temperature during MEMS bonding. This eliminates the need for grinding, forceful pulling, or hammering methods, thus preventing damage to the internal MEMS components, such as chip breakage. Furthermore, adjusting the temperature during unpacking using data on the material and temperature during MEMS bonding also avoids device damage, mitigating the technical problem of current MEMS unpacking methods that easily lead to device damage.

[0034] The steps described above will be explained in detail below.

[0035] In some embodiments, the process of removing the encapsulation of the first MEMS sample in step S110 may include the following steps: Step a) completely remove the encapsulation of the first MEMS sample by immersion in nitric acid at room temperature or by heating.

[0036] In this embodiment, the encapsulation of the first MEMS sample is completely removed by immersion in nitric acid at room temperature or by heating, which can make the removal of the encapsulation more thorough and avoid residue.

[0037] In some embodiments, the process of rinsing the third MEMS sample in step S130 above using a method other than ultrasound may include the following steps: Step b) Rinse the third MEMS sample with sulfuric acid, water, acetone or anhydrous ethanol.

[0038] Rinsing the third MEMS sample with sulfuric acid, water, acetone, or anhydrous ethanol can make the cleaning more thorough and avoid residues caused by incomplete cleaning.

[0039] In some embodiments, the process of heating the encapsulated MEMS wafer in the fourth MEMS sample in step S140 above may include the following steps: Step c) Place the encapsulated MEMS wafer in the fourth MEMS sample on a heating furnace that has been heated to a specified temperature and heated for a specified time.

[0040] As an optional method, specify a temperature between 400 and 500 degrees Celsius. Specify a duration between three and five minutes.

[0041] By placing the encapsulated MEMS wafer in the fourth MEMS sample on a furnace heated to 400 to 500 degrees Celsius for three to five minutes, the heating efficiency of the encapsulated MEMS wafer can be improved.

[0042] In some embodiments, the process of vertically separating the MEMS wafer and the MEMS capping in step S140 above may include the following steps: Step d) Use two iron-tipped tweezers to separate the MEMS chip and the MEMS cover by vertical clamping action. One of the iron-tipped tweezers is clamped on the MEMS chip, and the other iron-tipped tweezers is clamped on the MEMS cover. Step e): If the MEMS cover cannot be removed, continue heating the sealed MEMS chip and clamp it again.

[0043] In practical applications, the sealed MEMS die can be placed on a heating furnace and heated for three to five minutes. Two iron-tipped tweezers are used, one clamped on the MEMS die and the other on the MEMS sealing cover, and then lifted vertically. If the MEMS sealing cover cannot be removed, continue heating or increase the temperature again, and then try to remove it again. This can make the removal process of the MEMS sealing cover more precise and effective, and avoid damage to the device.

[0044] This application also provides a MEMS wafer bonding and unpacking device, which includes: a gripping device, a point temperature detection device, a heating device, and a control device; the heating device is used to heat the bonded MEMS wafer; the gripping device is used to vertically separate the heated MEMS wafer and the MEMS sealing cover through multiple sub-gripping devices to perform MEMS wafer bonding and unpacking; the point temperature detection device is used to detect the temperature at multiple points on the surface of the MEMS wafer to obtain the temperature detection results at multiple points; wherein, the multiple points are uniformly located on the surface of the MEMS wafer; the control device is used to control the gripping device to reduce the gripping force of the first sub-gripping device corresponding to the first point when the temperature detection result of the first point is less than a preset temperature threshold.

[0045] By employing a temperature-controlled opening method, MEMS opening eliminates the need for grinding, forceful pulling, or hammering, thus preventing chip breakage and other damage to internal MEMS components. Furthermore, a point-temperature detection device monitors multiple evenly distributed points on the MEMS wafer surface to determine the uniformity of temperature distribution. When a point's temperature is too low, the gripping device reduces its gripping force at that point, thereby reducing the gripping force at the low-temperature location. Since different temperatures at different points correspond to different force thresholds for the device, this solution prevents excessive gripping force at certain points during MEMS opening due to insufficient temperature, exceeding the device's force threshold and causing damage. This further alleviates the technical problem of device damage during MEMS opening.

[0046] In some embodiments, the MEMS wafer bonding and unpacking device further includes: a plurality of elastic devices and a force sensor; a plurality of sub-gripping devices are respectively disposed at a plurality of points on the surface of the MEMS wafer; the plurality of elastic devices are connected to the sub-gripping devices and are used to control the elastic gripping force of the sub-gripping devices; the force sensor is used to detect the elastic gripping force corresponding to each sub-gripping device; the control device is also used to control the gripping device to reduce the gripping force of the second sub-gripping device when the second elastic gripping force corresponding to the second sub-gripping device is greater than the preset gripping force.

[0047] The elastic device can buffer the excessive gripping force during the opening process. The force sensor and control device can control the gripping sub-device to reduce the gripping force when the gripping force of a certain gripping sub-device is too large, thereby further avoiding damage to the device during the opening process of MEMS.

[0048] In some embodiments, the point temperature detection device includes any one or more of the following: infrared temperature detector, thermal imaging device, and laser temperature detector.

[0049] By using various point temperature detection devices such as infrared temperature detectors, thermal imaging equipment, and laser temperature detectors, point temperature detection can be made more flexible and convenient.

[0050] In some embodiments, the point temperature detection device is an infrared temperature detector or a laser temperature detector, which is also connected to a control device. The control device is further configured to, when the temperature detection result of the first point is less than a preset temperature threshold, control the infrared light direction of the infrared temperature detector or the laser direction of the laser temperature detector to move toward the first point, so as to increase the temperature at the first point through the infrared light of the infrared temperature detector or the laser of the laser temperature detector.

[0051] By controlling the direction of the infrared light from the infrared temperature detector or the laser direction from the laser temperature detector to move towards the point where the temperature is too low when the temperature at a certain point is too low, the temperature at the first point can be increased by the infrared light from the infrared temperature detector or the laser direction from the laser temperature detector. This avoids the situation where the gripping force is too strong due to insufficient temperature at a certain point during the MEMS unpacking process, which could cause damage to the device. This further avoids device damage during the MEMS unpacking process.

[0052] In some embodiments, the control device is further configured to, when the second elastic gripping force corresponding to the second sub-gripping device is greater than the preset gripping force, control the infrared light direction of the infrared temperature detector or the laser direction of the laser temperature detector to move toward the second point, so as to increase the temperature at the second point by means of the infrared light of the infrared temperature detector or the laser of the laser temperature detector; wherein, the sub-gripping device corresponding to the second point is the second sub-gripping device.

[0053] When the elastic gripping force of the sub-gripping device at a certain point is too large, the infrared light direction of the infrared temperature detector or the laser direction of the laser temperature detector is moved towards the point of excessive gripping force. This can raise the temperature at the point of excessive gripping force by using the infrared light of the infrared temperature detector or the laser of the laser temperature detector. This avoids the situation where the gripping force is too large relative to the temperature during the MEMS unpacking process, which could cause device damage. This further prevents device damage during the MEMS unpacking process.

[0054] In some embodiments, the heating device is specifically used to heat the encapsulated MEMS wafer using hot circulating air. Heating the encapsulated MEMS wafer using hot circulating air can make the heating process more uniform, avoiding the situation where uneven temperature causes the gripping force to exceed the force threshold corresponding to the temperature at a certain point, resulting in device damage.

[0055] The MEMS wafer bonding and unpacking device provided in this application embodiment has the same technical features as the MEMS wafer bonding and unpacking method provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0056] The control device in this application embodiment can be a processor, which may be an integrated circuit chip with signal processing capabilities. In implementation, each step of the above method can be completed by the integrated logic circuitry in the processor's hardware or by software instructions. The processor can be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it can also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in this application embodiment. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this application embodiment can be directly manifested as execution by a hardware decoding processor, or execution by a combination of hardware and software modules in the decoding processor. Software modules can be located in mature storage media in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, and registers.

[0057] Corresponding to the above-described MEMS wafer bonding and unpacking method, this application embodiment also provides a computer-readable storage medium storing computer-executable instructions. When the computer-executable instructions are called and run by a processor, the computer-executable instructions cause the processor to perform the steps of the above-described MEMS wafer bonding and unpacking method.

[0058] The MEMS wafer bonding and unpacking device provided in this application embodiment can be specific hardware on the device or software or firmware installed on the device. The implementation principle and technical effects of the device provided in this application embodiment are the same as those in the foregoing method embodiments. For the sake of brevity, any parts not mentioned in the device embodiment can be referred to the corresponding content in the foregoing method embodiments. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can all be referred to the corresponding processes in the above method embodiments, and will not be repeated here.

[0059] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and there may be other division methods in actual implementation. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interface; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0060] For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0061] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0062] In addition, the functional units in the embodiments provided in this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0063] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the MEMS wafer bonding and unpacking methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0064] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] Finally, it should be noted that the above embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A method for opening a MEMS wafer bonding package, characterized in that, The method includes: The encapsulation of the first MEMS sample is removed, and the bonding lines between the ASIC and the MEMS sample are removed to obtain the second MEMS sample. The second MEMS sample is immersed in anhydrous ethylenediamine at room temperature or under heat until the ASIC separates from the MEMS sample, thus obtaining the third MEMS sample. The third MEMS sample is removed from anhydrous ethylenediamine at room temperature or heated, and then rinsed by a method other than ultrasound to obtain the fourth MEMS sample. The MEMS wafer in the fourth MEMS sample is heated, and the MEMS wafer and the MEMS sealing cover are vertically separated to perform MEMS wafer bonding unsealing.

2. The method according to claim 1, characterized in that, The removal of the encapsulation from the first MEMS sample includes: The encapsulation of the first MEMS sample was completely removed by immersion in nitric acid at room temperature or by heating.

3. The method according to claim 1, characterized in that, The washing of the third MEMS sample by means other than ultrasound includes: The third MEMS sample was rinsed with sulfuric acid, water, acetone or anhydrous ethanol.

4. The method according to claim 1, characterized in that, The step of heating the encapsulated MEMS wafer in the fourth MEMS sample includes: The encapsulated MEMS wafer in the fourth MEMS sample is placed in a heating furnace that has been heated to a specified temperature and heated for a specified time.

5. The method according to claim 4, characterized in that, The specified temperature is between 400 and 500 degrees Celsius.

6. The method according to claim 4, characterized in that, The specified duration is between three and five minutes.

7. The method according to claim 1, characterized in that, The vertical separation between the MEMS wafer and the MEMS cap includes: The MEMS wafer and the MEMS cover are separated by using two iron-tipped tweezers through a vertical clamping action, wherein one of the two iron-tipped tweezers is clamped on the MEMS wafer and the other iron-tipped tweezers is clamped on the MEMS cover; If the MEMS sealing cap cannot be removed, continue heating the sealed MEMS wafer and clamp it again.

8. The method according to claim 1, characterized in that, Before removing the molding compound of the first MEMS sample and the bonding lines between the ASIC and the MEMS sample to obtain the second MEMS sample, the procedure further includes: X-rays are used to determine the internal structure of the MEMS, whether the package contains a MEMS chip, and whether the chip has a substrate. If the substrate is present, it is first ground off before the die is obtained.

9. The method according to claim 1, characterized in that, After vertically separating the MEMS wafer and the MEMS cap to perform MEMS wafer bonding unpacking, the process further includes: Optical microscopes are used to determine internal failure points or obtain internal structural information of MEMS, so as to observe the internal structure of MEMS and the MEMS silicon cap during the opening process of MEMS.

10. The method according to claim 4, characterized in that, The specified temperature is obtained by adjusting the data of the material and temperature during MEMS bonding.

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