Defect Analysis Method of Fingerprint Recognition Module

Abstract

The embodiment of the present application proposes a defect analysis method for a fingerprint recognition module. The fingerprint recognition module includes a substrate, a chip, a cover plate located above the chip, a first bonding layer for bonding the chip and the cover plate, and a frame. The chip includes a chip body, a metal layer for connecting to the substrate, and an electronic device layer arranged on the side of the chip body close to the cover plate. The defect analysis method for the fingerprint recognition module includes: removing the substrate to obtain a first sample; embedding the first sample in an embedding material using an inlay process to form a second sample; grinding the second sample from the side close to the metal layer using a step grinding method to remove the metal layer to form a third sample; immersing the third sample in a caustic solution, and heating the caustic solution to remove the chip body to form a fourth sample; locating defects in the fourth sample, and using a focused ion beam microscope to perform cross-sectional analysis on the defect. The embodiment of the present application is conducive to improving analysis efficiency and accuracy.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a defect detection method for a fingerprint recognition module. Background Art

[0002] In recent years, fingerprint recognition technology has penetrated into every aspect of life. Fingerprint recognition technology is based on the fact that the fingerprint skin texture and detailed features of different people are different, that is, each person's fingerprint is unique, and by comparing the current user's fingerprint with the pre-saved fingerprint data, it confirms whether the current user is the user himself.

[0003] Fingerprint recognition technology is implemented by fingerprint recognition sensors. Common fingerprint recognition sensors include capacitive fingerprint recognition modules, optical fingerprint recognition modules, and ultrasonic fingerprint recognition modules. Common fingerprint recognition modules include a substrate, a chip electrically connected to the substrate, a cover plate located on the chip, a first bonding layer bonding the chip and the cover plate, and a frame. The frame is arranged on the substrate and surrounds the chip, the cover plate, and the first bonding layer. During the assembly process of the fingerprint recognition module, the electronic devices in the chip are prone to cracks, holes, and other defects, and the chip and the cover plate are prone to poor alignment, incomplete glue dispensing, and other defects. At the same time, the first bonding layer between the chip and the cover plate may also be mixed with dust in the environment, dandruff on the human body, and impurities such as residues of other components. These defects will affect the normal use of the fingerprint recognition module. Therefore, it is necessary to perform cross-sectional analysis on these defects to determine the abnormal cause of the fingerprint recognition module.

[0004] In the related art, the defect analysis method for the fingerprint recognition module is to determine the relative position of the abnormal point by positioning means after removing the cover plate, and mark the abnormal position. Then the marked sample is sent to the FIB machine for cross-section cutting. However, due to the thickness of the fingerprint recognition module itself, the cutting efficiency is low and the time consumption is long. In addition, it may also cause errors in the marking, thereby reducing the success rate of cross-section analysis. Summary of the invention

[0005] Based on this, it is necessary to provide a defect analysis method for a fingerprint recognition module to improve the analysis efficiency and success rate.

[0006] The embodiment of the present application proposes a defect analysis method for a fingerprint recognition module. The fingerprint recognition module includes a substrate, a chip electrically connected to the substrate, a cover plate located above the chip, a first adhesive layer bonding the chip and the cover plate, and a frame, the frame is arranged on the substrate and surrounds the chip, the cover plate and the first adhesive layer, the chip includes a chip body, a metal layer for connecting to the substrate, and an electronic device layer arranged on the side of the chip body close to the cover plate. The defect analysis method of the fingerprint recognition module includes:

[0007] removing the substrate to obtain a first sample;

[0008] Embedding the first sample in an embedding material using an embedding process to form a second sample;

[0009] Grinding the second sample from a side close to the metal layer by step grinding to remove the metal layer, thereby forming a third sample;

[0010] soaking the third sample in a caustic solution, and heating the caustic solution to remove the chip body to form a fourth sample;

[0011] Defects of the fourth sample are located, and a focused ion beam microscope is used to perform cross-sectional analysis on the defects.

[0012] The defect analysis method of the fingerprint recognition module of the embodiment of the present application removes unnecessary components that affect subsequent analysis, such as substrates, metal layers, and chip bodies, by physically dismantling, grinding, and immersing and dissolving the fingerprint recognition module in a solution, thereby reducing the thickness of the sample and requiring a smaller cutting depth during subsequent cross-section cutting, thereby facilitating improved analysis efficiency. In addition, after the sample thickness is reduced, the electronic device layer of the chip is completely exposed, which can be directly used as a coordinate for defect location, thereby also facilitating improved accuracy of defect analysis.

[0013] In some embodiments, the temperature of the caustic solution is 100°C-185°C.

[0014] In some embodiments, the step of immersing the third sample in a caustic solution and heating the caustic solution further comprises:

[0015] The caustic soda solution is stirred at a rate of 100 to 300 rpm.

[0016] In some embodiments, the concentration of the caustic solution is 10 mol / L-30 mol / L.

[0017] In some embodiments, the step of embedding the first sample in a embedding material using an embedding process comprises:

[0018] Providing molds for inlay craft;

[0019] placing the first sample in the mold and injecting a mounting material into the mold;

[0020] After the mounting material has cured, the mold is removed.

[0021] In some embodiments, the shape of the mold includes a cylinder, a cube, or a cuboid.

[0022] In some embodiments, the mounting process includes one of a hot mounting process and a cold mounting process.

[0023] In some embodiments, the step of locating defects in the fourth sample and performing cross-sectional analysis on the defects using a focused ion beam microscope includes:

[0024] Using at least one of an optical emission microscope (EMMI), an optical impedance change microscope (OBIRCH), and a thermal emission microscope (Thermal) to locate defects on the fourth sample;

[0025] Use a laser marker to mark the defects;

[0026] The marked positions were cut using a focused ion beam microscope for cross-sectional analysis.

[0027] In some embodiments, the ion beam voltage of the focused ion beam microscope is 30 kV, and the current is one of 60 nA, 15 nA, and 4 nA.

[0028] In some embodiments, the fingerprint recognition module further includes a supporting back plate disposed on a side of the substrate away from the chip and a second adhesive layer for bonding the substrate and the supporting back plate, and the defect analysis method of the fingerprint recognition module further includes:

[0029] The supporting back plate and the second adhesive layer are removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of the decomposition structure of a fingerprint recognition module according to an embodiment of the present application;

[0031] Figure 2 A schematic diagram of the structure of a chip according to an embodiment of the present application;

[0032] Figure 3 A flow chart of a defect analysis method for a fingerprint recognition module according to an embodiment of the present application;

[0033] Figure 4 A schematic diagram of the structure of the second sample of the embodiment of the present application;

[0034] Figure 5 This is a schematic diagram of the structure of the third sample of the embodiment of the present application.

[0035] The reference numerals are as follows:

[0036] 10: fingerprint recognition module; 100- substrate;

[0037] 200: chip; 210-metal layer;

[0038] 220: electronic device layer; 230- chip body;

[0039] 300: cover plate; 400- first adhesive layer;

[0040] 500: frame; 600- support back panel;

[0041] 610: second bonding layer; 700- inlay material;

[0042] A: first sample; B: second sample;

[0043] C: The third sample. DETAILED DESCRIPTION

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0045] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0046] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0047] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0049] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0050] like Figure 1 , which is a schematic diagram of the exploded structure of a fingerprint recognition module 10 according to an embodiment of the present application. The fingerprint recognition module 10 includes a substrate 100, a chip 200 electrically connected to the substrate 100, a cover plate 300 located on the chip 200, a first adhesive layer 400 for bonding the chip 200 and the cover plate 300, and a frame 500. The frame 500 is disposed on the substrate 100 and surrounds the chip 200, the cover plate 300, and the first adhesive layer 400. Figure 2As shown, the chip 200 includes a chip body 230 , a metal layer 210 for connecting with the substrate 100 , and an electronic device layer 220 disposed on a side of the chip body 230 close to the cover plate 300 .

[0051] The substrate 100 refers to a substrate structure for carrying the chip 200. The substrate 100 may be a hard substrate or a soft substrate. In some embodiments, the substrate 100 is a hard substrate, and the hard substrate is one of a PCB substrate, a glass substrate, a metal substrate, a semiconductor substrate, or a polymer substrate. In other embodiments, Figure 1 As shown, the substrate 100 can be a flexible circuit board, and the metal layer 210 of the chip 200 is bound and joined to the pins of the flexible circuit board to implement chip on film packaging, which is conducive to making the fingerprint recognition module 10 thin and light.

[0052] The chip 200 is a core component for realizing fingerprint recognition. The chip 200 includes a chip body 230, a metal layer 210 and an electronic device layer 220. The chip body 230 refers to the silicon-based material of the chip 200. The chip 200 is electrically connected to the substrate 100 through the metal layer 210 on the chip body 230. In addition, the electronic device layer 220 is formed on the chip body 230 by photolithography technology, so that the collection of human fingerprints can be realized through the electronic device layer 220. The cover plate 300 refers to a component for protecting the chip 200 and for human finger touch. The material of the cover plate 300 may include sapphire, ceramic or glass, etc., and this application does not limit this. The first adhesive layer 400 is usually an epoxy resin adhesive layer to realize the connection between the chip 200 and the cover plate 300. The frame 500 is used to protect the chip 200, the cover plate 300 and the first adhesive layer 400 inside it to improve the structural stability of the fingerprint recognition module 10. The frame 500 can be fixed to the substrate 100 by glue. In some embodiments, the frame 500 can be made of metal material, which is conducive to achieving static protection of the fingerprint recognition module 10 while fixing and protecting the internal structure.

[0053] The working principle of the fingerprint recognition module 10 is as follows: when the user's finger touches the surface of the cover plate 300, the distances between the ridges and valleys on the finger and the chip 200 are different. Therefore, the capacitance values ​​between the ridges or valleys of the user's finger and the electronic device layer 220 are different, so that the chip 200 can obtain different capacitance values ​​and convert them into corresponding electrical signal outputs, thereby obtaining the user's fingerprint information.

[0054] During the assembly process of the fingerprint recognition module 10, the electronic device layer 220 in the chip 200 is prone to cracks, holes and other defects, the chip 200 and the cover plate 300 are prone to poor alignment, incomplete glue dispensing and other defects, and the first adhesive layer 400 between the chip 200 and the cover plate 300 may also be mixed with dust in the environment, human dandruff and residues of other components. These defects will affect the normal use of the fingerprint recognition module 10. Therefore, it is necessary to perform cross-sectional analysis on these defects to determine the abnormal cause of the fingerprint recognition module 10.

[0055] In the related art, when performing cross-sectional analysis on the above-mentioned fingerprint recognition module 10, only the substrate 100 is removed, so that the thickness of the sample after removal is relatively thick, usually exceeding 120 μm, resulting in low efficiency and long cutting time. In addition, after removing the substrate 100, other film layers such as the metal layer 210 and the chip body 230 still exist, which may also cause errors in the marking, thereby reducing the success rate of the cross-sectional analysis.

[0056] Based on this, the present application proposes a defect analysis method for the fingerprint recognition module 10 to improve the efficiency and success rate of cross-sectional analysis.

[0057] like Figure 3 As shown, the defect analysis method of the fingerprint recognition module 10 of the present application includes:

[0058] The substrate 100 is removed to obtain a first sample A;

[0059] The first sample A is embedded in the embedding material 700 by using an embedding process to form a second sample B;

[0060] The second sample B is ground from a side close to the metal layer 210 by step grinding to remove the metal layer 210 to form a third sample C.

[0061] The third sample C is immersed in a caustic solution, and the caustic solution is heated to remove the chip body 230 to form a fourth sample;

[0062] The defects of the fourth sample were located, and a focused ion beam microscope was used to perform cross-sectional analysis on the defects.

[0063] In the present application, the film layer of the fingerprint recognition module 10 is thinned by grinding and dissolving with a caustic solution. Figure 4As shown, the substrate 100 is first removed by physical disassembly. Then, the first sample A after the substrate 100 is removed is subjected to an inlay process to form a second sample B of a certain shape. That is, the first sample A is the remaining part of the fingerprint recognition module 10 after the substrate 100 is removed, and the second sample B is composed of the first sample A and the inlay material 700 that wraps the first sample A. The inlay process is a commonly used method in the field of metallographic analysis. The inlay process treatment of the first sample A is conducive to improving the subsequent grinding convenience and immersion safety of the sample, thereby improving the grinding efficiency and the accuracy of the analysis.

[0064] Then, the second sample B is ground from the side close to the metal layer 210 by step grinding until the metal layer 210 is removed, thus obtaining the third sample C. Figure 5 As shown, the third sample C is the remaining portion of the second sample B after removing the metal layer 210 and the material in the same layer as the metal layer 210. In some embodiments, a high-precision grinder can be used to implement step grinding of the metal layer 210. Furthermore, during grinding, only the metal layer 210 can be removed, retaining the complete chip body 230 and the electronic device layer 220. In this way, it is beneficial to maintain the complete chip body 230 and the electronic device layer 220 structure and reduce the probability of failure of defect analysis. Alternatively, it is also possible to continue grinding after removing the metal layer 210 to remove a portion of the thickness of the chip body 230. It is easy to understand that at this time, the depth of continued grinding cannot be too deep to avoid over-grinding, thereby damaging the electronic device layer 220 on the chip 200.

[0065] Next, the third sample C is immersed in a caustic solution, and the caustic solution is heated to remove the chip body 230, thereby forming a fourth sample. That is, the fourth sample is the remaining portion of the third sample C after removing the chip body 230, i.e., the silicon-based material. The chip body 230 can react chemically with the caustic solution. The reaction equations of the two are:

[0066] Si 2+ +2H2O+2OH - →Si(OH)2O2 2- +2H2

[0067] Thus, the chip body 230 in the third sample C will dissolve in the caustic solution, so that only the electronic device layer 220 remains in the chip 200. Further, the caustic solution may include one of a sodium hydroxide solution and a potassium hydroxide solution, which is not limited in the present application.

[0068] In a specific embodiment, after the metal layer 210 is removed by grinding, the chip body 230 is further ground so that the thickness of the remaining chip 200 is not less than 3 μm. In this way, on the one hand, over-grinding can be avoided, and on the other hand, the thickness of the chip body 230 can be reduced, so that the subsequent caustic solution dissolving time of the chip body 230 is shortened, which is conducive to improving the analysis efficiency.

[0069] Finally, the fourth sample is defect-located, and a focused ion beam microscope is used to perform cross-sectional analysis of the defect. Since the fourth sample directly exposes the electronic device layer 220, the electronic device layer 220 can be used as a positioning surface, and the defect position can be determined by positioning means, which is conducive to improving positioning accuracy and positioning efficiency. The defect may be a crack, a hole, etc. in the electronic device layer 220, or poor alignment between the chip 200 and the cover plate 300, incomplete dispensing, etc., or impurities such as dust mixed in the first adhesive layer 400, dandruff on the human body, and residues of other components. After determining the defect location, a focused ion beam microscope is used to perform cross-sectional cutting of the defect, and then the specific cause of the defect is analyzed.

[0070] The defect analysis method of the fingerprint recognition module 10 of the embodiment of the present application removes unnecessary components that affect subsequent analysis, such as the substrate 100, the metal layer 210, the chip body 230, etc., by physically dismantling, grinding, and immersing and dissolving the fingerprint recognition module 10 in turn, so that the sample thickness is thinned, and the depth required for cutting is small during subsequent cross-section cutting, which is beneficial to improving the analysis efficiency. In addition, after the sample thickness is thinned, the electronic device layer 220 of the chip 200 is completely exposed, which can be directly used as the coordinate for defect positioning, which is also beneficial to improving the accuracy of defect analysis.

[0071] In some embodiments, in order to enhance the strength of the fingerprint recognition module 10, Figure 1 As shown, a support back plate 600 is further provided on the side of the substrate 100 away from the chip 200, and the support back plate 600 is bonded to the substrate 100 through a second bonding layer 610. If the material of the support back plate 600 is metal, it is also beneficial to improve the heat dissipation effect of the fingerprint recognition module 10. Furthermore, the defect analysis method of the fingerprint recognition module 10 also includes:

[0072] The supporting back plate 600 and the second adhesive layer 610 are removed.

[0073] That is, if the side of the substrate 100 facing away from the chip 200 is provided with a supporting back plate 600 and a second adhesive layer 610, it is necessary to physically remove the supporting back plate 600 and the second adhesive layer 610 before removing the substrate 100. Usually, the second adhesive layer 610 is adhesive glue, so the supporting back plate 600 and the second adhesive layer 610 can be removed in sequence by heating and scraping.

[0074] In some embodiments, the temperature of the caustic solution is 100° C.-185° C. The temperature of the caustic solution will affect the efficiency of dissolution. The heating temperature of the caustic solution is within the above range, which is conducive to improving the dissolution efficiency while ensuring safety.

[0075] In some embodiments, the step of immersing the third sample C in a caustic solution and heating the caustic solution further comprises:

[0076] The caustic solution is stirred at a rate of 100 to 300 rpm. By stirring the caustic solution, it is beneficial to improve the uniformity of the temperature and concentration of the solution, thereby improving the uniformity and efficiency of dissolution. Furthermore, the stirring rate is 100 to 300 rpm, so that the stirring rate is not too fast, thereby helping to reduce the probability of solution overflow. The stirring method may include magnetic stirring, mechanical stirring, etc., and the present application is not limited to this.

[0077] In some embodiments, the concentration of the caustic solution is 10 mol / L-30 mol / L. The dissolution efficiency of the chip body 230 in the caustic solution is also closely related to the concentration of the caustic solution. When the concentration of the caustic solution is within the above range, it is beneficial to improve the dissolution efficiency of the chip body 230 in the caustic solution, thereby improving the analysis efficiency.

[0078] In some embodiments, the step of embedding the first sample A in the embedding material 700 by using an embedding process includes:

[0079] Providing molds for inlay craft;

[0080] Place the first sample A in the mold, and inject the inlay material 700 into the mold;

[0081] After the mounting material 700 is cured, the mold is removed.

[0082] The inlay process is a common curing packaging technology in metallographic sample preparation. Since the first sample A is the structure of the fingerprint recognition module 10 without the substrate 100, its shape is irregular. If it is directly ground, it may make grinding difficult. In addition, since the substrate 100 has been removed, if the first sample A is directly immersed in a caustic solution, the structure of the first sample A may also be damaged. Therefore, by embedding the first sample A in the inlay material 700, it is beneficial to protect the first sample A and ensure the structural integrity of the sample, and it is also beneficial to improve the convenience of subsequent grinding.

[0083] Furthermore, the shape of the mold includes a cylinder, a cube, or a cuboid. In this way, the first sample A is formed into a second sample B with a regular shape after the inlay process, which is conducive to improving the grinding convenience. Figure 4 As shown, the second sample B is cylindrical. It is easy to understand that the shapes of the commonly used polyhedrons are listed here. The shape of the mold can also be other polyhedrons, as long as the subsequent grinding process can be completed, and this application does not limit this.

[0084] Since the fingerprint recognition module 10 has a stable structure, can withstand a certain pressure, and does not contain heat-sensitive materials, in some embodiments, the inlay process may include one of a hot inlay process and a cold inlay process.

[0085] The hot embedding process refers to a process of embedding samples at high temperature. That is, after the first sample A is placed in the mold, a hot embedding material is added to the mold. At this time, a certain temperature needs to be maintained and a certain pressure needs to be applied so that the hot embedding material wraps the first sample A. Finally, the second sample B is formed by curing and demolding. Furthermore, the embedding material 700 used in the hot embedding process can include thermosetting resins and thermoplastic resins. Thermosetting resins will gradually solidify at high temperatures, while thermoplastic resins will gradually soften or melt at high temperatures and solidify when cooled.

[0086] The cold mounting process refers to a process of mounting a sample at room temperature. That is, after the first sample A is placed in the mold, the cold mounting material is added to the mold, and then cross-linking and curing occurs. No heating or pressurization is required in this process. Further, the mounting material 700 of the cold mounting process may include epoxy resin and acrylic resin. Among them, the epoxy resin includes two parts, a resin and a curing agent. In this embodiment, the ratio of the two can be 10:1.

[0087] The hot mounting process produces samples of higher quality, with a short curing time and fast molding, which is conducive to improving analysis efficiency. The cold mounting process has a lower production cost, which is conducive to reducing analysis costs. Those skilled in the art can flexibly select the mounting process according to actual needs.

[0088] In some embodiments, the step of locating defects on the fourth sample and performing cross-sectional analysis on the defects using a focused ion beam microscope includes:

[0089] Using at least one of an optical emission microscope (EMMI), an optical impedance change microscope (OBIRCH), and a thermal emission microscope (Thermal) to locate defects on the fourth sample;

[0090] Use a laser marker to mark the defects;

[0091] The marked positions were cut using a focused ion beam microscope for cross-sectional analysis.

[0092] In this embodiment, some methods for defect location are specifically described, and of course, the methods for defect location are not limited to the above methods. By directly locating the defect on the level of the electronic device layer 220, laser marking the defect, and combining multiple positioning methods, it is beneficial to improve the accuracy of defect location, thereby improving the success rate of analysis.

[0093] Furthermore, the ion beam voltage of the focused ion beam microscope is 30kV, and the current is one of 60nA, 15nA, and 4nA. When performing cross-section cutting, the current of the focused ion beam microscope can be changed according to the cutting depth. For example, when performing preliminary cutting, due to the large cutting depth, the current can be set to 60nA at this time, the microscope has a large power, and the cutting efficiency is high. Then, as the cutting depth gets closer and closer to the depth position of the defect, in order to avoid damaging the cross section at the defect during cutting, the current of the focused ion beam microscope can be gradually reduced from 60nA to 15nA, 4nA, so that the power of the microscope is gradually reduced, and finally a cross-sectional fault that can be analyzed is formed. This is conducive to improving the success rate of defect analysis.

[0094] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0095] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A defect analysis method for a fingerprint recognition module, the fingerprint recognition module comprising a substrate, a chip electrically connected to the substrate, a cover plate located above the chip, a first bonding layer bonding the chip and the cover plate, and a frame, the frame being arranged on the substrate and surrounding the chip, the cover plate, and the first bonding layer, the chip comprising a chip body, a metal layer for connecting to the substrate, and an electronic device layer arranged on a side of the chip body close to the cover plate, characterized in that: The defect analysis method of the fingerprint recognition module includes: removing the substrate to obtain a first sample; Embedding the first sample in an embedding material using an embedding process to form a second sample; Grinding the second sample from a side close to the metal layer by step grinding to remove the metal layer, thereby forming a third sample; soaking the third sample in a caustic solution, and heating the caustic solution to remove the chip body to form a fourth sample; Defects of the fourth sample are located, and a focused ion beam microscope is used to perform cross-sectional analysis on the defects.

2. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The temperature of the caustic solution is 100°C-185°C.

3. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The step of immersing the third sample in a caustic solution and heating the caustic solution further comprises: The caustic soda solution is stirred at a rate of 100 to 300 rpm.

4. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The concentration of the caustic solution is 10 mol / L-30 mol / L.

5. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The step of embedding the first sample in the embedding material by using the embedding process comprises: Providing molds for inlay crafts; placing the first sample in the mold and injecting a mounting material into the mold; After the mounting material has cured, the mold is removed.

6. The defect analysis method of the fingerprint recognition module according to claim 5, characterized in that: The shape of the mold includes a cylinder, a cube, or a cuboid.

7. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The inlay process includes one of a hot inlay process and a cold inlay process.

8. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The step of locating defects in the fourth sample and performing cross-sectional analysis on the defects using a focused ion beam microscope comprises: Using at least one of a photon radiation microscope, a light value resistance value change microscope, and a thermal emission microscope to locate defects in the fourth sample; Use a laser marking machine to mark defects; The marked positions were cut using a focused ion beam microscope for cross-sectional analysis.

9. The defect analysis method of the fingerprint recognition module according to claim 8, characterized in that: The ion beam voltage of the focused ion beam microscope is 30 kV, and the current is one of 60 nA, 15 nA, and 4 nA.

10. The defect analysis method of the fingerprint recognition module according to claim 1, characterized in that: The fingerprint recognition module further includes a supporting back plate disposed on a side of the substrate away from the chip and a second adhesive layer for bonding the substrate and the supporting back plate. The defect analysis method of the fingerprint recognition module further includes: The supporting back plate and the second adhesive layer are removed.

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