Chip polishing method

Abstract

The application discloses a chip polishing method, and steps are as follows: preparing a sample to be processed and a hard carrier sheet, the sample comprising a chip and a frame, the chip being connected to the front surface of the frame, and the carrier sheet having a first surface and a second surface arranged oppositely; adhering the back surface of the frame to the first surface of the carrier sheet; coating an isolation layer on at least the outer side surface of the chip, coating a reinforcing layer on the outer side surface of the isolation layer, and exposing at least the second surface of the carrier sheet; polishing the chip from the second surface until the chip remains a set thickness; and removing the isolation layer to separate the sample from the reinforcing layer. The back surface of the sample is adhered to the first surface of the carrier sheet, and no adhesive exists between the two, so that the sample cannot be skewed relative to the carrier sheet due to uneven adhesive thickness, and the problem of uneven thickness of the chip after polishing can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of failure detection of semiconductor devices, and in particular to a chip polishing method. BACKGROUND

[0002] In the process of failure detection of a chip, in order to find out the defects generated inside the chip, the back surface of the chip needs to be polished to facilitate the observation of the internal defects of the chip through an infrared microscope or the positioning of the failure point by using an EMMI (Emission Microscope). In the related art, the front surface of the chip is usually adhered to a jig by an adhesive, and then the jig is fixed on a polishing device, and the back surface of the chip is polished. Since the flow of the adhesive is difficult to control, the adhesive is prone to have a non-uniform thickness problem, and the chip cannot be fixed horizontally, so that the polishing amount of different areas is inconsistent in the subsequent polishing process, resulting in that the thickness of the finally obtained chip is non-uniform, which affects the detection result. SUMMARY

[0003] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a chip polishing method, which can improve the problem of non-uniform thickness of the chip after polishing.

[0004] The chip polishing method according to the first embodiment of the present application comprises the following steps:

[0005] A sample to be processed and a hard carrier sheet are prepared, the sample comprises a chip and a frame, the chip is connected to the front surface of the frame, and the carrier sheet has a first surface and a second surface arranged opposite to each other;

[0006] The back surface of the frame is attached to the first surface of the carrier sheet;

[0007] An isolation layer is coated on at least the outer side surface of the chip, and a reinforcing layer is coated on the outer side surface of the isolation layer, and at least the second surface of the carrier sheet is exposed;

[0008] The chip is polished from the second surface until the chip remains a set thickness;

[0009] The isolation layer is removed to separate the sample from the reinforcing layer.

[0010] The chip polishing method according to the first embodiment of the present application has at least the following beneficial effects:

[0011] The back surface of the sample is attached to the first surface of the carrier sheet, and there is no adhesive between them, so the sample will not be skewed relative to the carrier sheet due to the non-uniform thickness of the adhesive, which helps to improve the problem of non-uniform thickness of the chip after polishing.

[0012] In other embodiments of the invention, the isolation layer covers the outer surfaces of the frame other than the back side, and the isolation layer is connected to the first surface of the carrier piece.

[0013] In other embodiments of the present invention, the method for setting the isolation layer includes:

[0014] After the sample is placed on the carrier sheet, a solid insulating material is applied to the top of the chip;

[0015] The insulating material is heated to melt it and allow it to flow downwards to the carrier sheet, thereby covering the chip and the frame.

[0016] The molten insulating material is solidified to form the insulating layer.

[0017] In other embodiments of the present invention, the material of the insulating layer is paraffin wax, and the heating temperature is 100°C to 105°C.

[0018] In other embodiments of the invention, the reinforcing layer covers the outer surfaces of the carrier sheet other than the second surface.

[0019] In other embodiments of the present invention, the method for setting the enhancement layer includes:

[0020] A mold with a receiving cavity is provided, and the carrier piece carrying the sample is placed in the mold so that the second surface is in contact with the bottom wall of the receiving cavity;

[0021] Add liquid reinforcing material into the accommodating cavity until the liquid level is higher than the insulating layer;

[0022] The liquid reinforcing material is solidified to form the reinforcing layer.

[0023] In other embodiments of the present invention, the reinforcing layer is made of resin.

[0024] In other embodiments of the present invention, the carrier sheet, the frame and the chip are polished respectively using sandpaper with gradually increasing grit.

[0025] The chip polishing method according to the fifth embodiment of the present invention includes the following steps:

[0026] Prepare a carrier sheet and a chip to be processed, wherein the carrier sheet has a first surface and a second surface disposed opposite to each other;

[0027] The back side of the chip is attached to the first surface of the carrier sheet;

[0028] An isolation layer is wrapped around the outside of the chip, and a reinforcement layer is wrapped around the outside of the isolation layer, so that at least the second surface of the carrier sheet is exposed;

[0029] Polishing begins from the second surface until the chip reaches the set thickness;

[0030] Remove the isolation layer to separate the chip from the reinforcement layer.

[0031] The chip polishing method according to the sixth embodiment of the present invention includes the following steps:

[0032] Prepare a carrier sheet and a sample to be processed. The sample includes a mold, a chip and a frame located within the mold, the chip being connected to the front side of the frame, and the carrier sheet having a first surface and a second surface disposed opposite to each other.

[0033] The back side of the molded body is attached to the first surface of the carrier sheet;

[0034] An isolation layer is wrapped around the outside of the molded body, and a reinforcing layer is wrapped around the outside of the isolation layer, so that at least the second surface of the carrier sheet is exposed;

[0035] Polishing begins from the second surface and proceeds toward the chip until the chip retains a predetermined thickness.

[0036] Remove the isolation layer to separate the sample from the reinforcement layer.

[0037] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0039] Figure 1 This is a simplified schematic diagram of the connection between the chip and the fixture in the related technology;

[0040] Figure 2 This is a simplified schematic diagram of the chip after polishing in related technologies;

[0041] Figure 3 This is a schematic diagram of the internal structure of a typical sample to which this invention applies;

[0042] Figure 4 This is a diagram showing the state changes of a sample during polishing using the polishing method of the first embodiment;

[0043] Figure 5 This is a schematic diagram showing the chamfered edges on the sides of a chip after polishing using relevant technologies.

[0044] Figure 6 This is a diagram showing the state changes of a sample during polishing using the polishing method of the second embodiment;

[0045] Figure 7 This is a schematic diagram of the formation of the isolation layer in the second embodiment;

[0046] Figure 8 This is a diagram showing the state changes of a sample during polishing using the polishing method of the third embodiment;

[0047] Figure 9 This is a schematic diagram of the formation of the reinforcement layer in the third embodiment;

[0048] Figure 10 This is a diagram showing the state changes of a sample during polishing using the polishing method of the fourth embodiment;

[0049] Figure 11 This is a diagram showing the state changes of a sample during polishing using the polishing method of the fifth embodiment;

[0050] Figure 12 This is a diagram showing the state changes of a sample during polishing using the polishing method of the sixth embodiment.

[0051] Figure label:

[0052] Support plate 100, first surface 110, second surface 120;

[0053] Sample 200, mold body 210, chip 220, frame 230;

[0054] 300mm isolation layer;

[0055] Reinforcement layer 400;

[0056] Heating device 500;

[0057] Mold 600, receiving cavity 610;

[0058] Sample 10, chamfer 11, adhesive 20, fixture 30. Detailed Implementation

[0059] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0060] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0061] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0062] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0063] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] In related technologies, if chip polishing is required to analyze internal defects, the back side of the sample 10 to be processed is typically bonded to a fixture 30 using an adhesive 20. Before bonding, a flowable adhesive 20 needs to be applied to the sample 10 and / or the fixture 30. However, the flow of the adhesive 20 is difficult to control precisely, leading to uneven thickness. Even if the thickness of the adhesive 20 is uniform before bonding, misalignment can easily occur during the docking of the sample 10 and the fixture 30, ultimately resulting in... Figure 1 The skewed state shown.

[0065] When sample 10 Figure 1 When the skewed state shown is in contact with the horizontal grinding surface and is being ground, the amount of grinding varies in different areas, resulting in uneven thickness in the final sample 10. For example... Figure 1The grinding amount on the left side is greater than that on the right side, resulting in a thinner left side than the right side of the final sample 10. Therefore, when the thickness of the left side of sample 10 meets the requirements, the right side may be too thick, obscuring the internal structure and affecting the detection results. Based on this, the present invention proposes a chip grinding method that ensures uniform thickness of the chip 220 after grinding. The following is a detailed description with reference to the accompanying drawings.

[0066] In the first embodiment of the present invention, the sample 200 to which the polishing method is applicable can be a power module, such as... Figure 3 As shown, a typical sample 200 includes a chip 220 and a frame 230. The chip 220 is typically a cuboid structure. The surface of the chip 220 with leads is defined as the front side of the chip 220, and the surface opposite the front side is defined as the back side. Specifically... Figure 3 In this context, the upper surface of chip 220 is considered the front, and the lower surface is considered the back. It should be noted that, for ease of description, for other components mentioned in this invention, the upper surface when horizontally placed is considered the front, and the lower surface is considered the back. Based on this, the back of chip 220 is connected to the front of frame 230.

[0067] The sample 200 applicable to this embodiment may also include a molding compound 210. The material of the molding compound 210 is usually epoxy resin. The molding compound 210 encapsulates the chip 220 and the frame 230 to provide insulation and protection. To reduce the amount of polishing, the molding compound 210 on the sample 200 is usually removed first to expose the chip 220 and the frame 230. Acid can be used to remove the molding compound 210 on the outside of the sample 200. It should be noted that the sample 200 may arrive with the molding compound 210, which needs to be removed before polishing. Alternatively, the molding compound 210 can be removed before the sample 200 arrives.

[0068] Reference Figure 4 The diagram shows the state changes of sample 200 during polishing using the polishing method of the first embodiment. The polishing method includes the following steps, from top to bottom:

[0069] Step 1: Prepare a sample 200 with the molded body 210 removed. The sample 200 includes a frame 230 and a chip 220 placed on the front of the frame 230.

[0070] Step 2: Place the sample 200 on the support sheet 100. The support sheet 100 has a first surface 110 and a second surface 120, where the first surface 110 is located on the upper side of the figure and the second surface 120 is located on the lower side of the figure. Specifically, the sample 200 is attached to the first surface 110 of the support sheet 100 through the back of the frame 230. The support sheet 100 is a rigid sheet of uniform thickness, which can prevent the support sheet 100 from deforming and can also serve as a reference to ensure the horizontal placement of the sample 200. In some specific embodiments, the support sheet 100 can be a metal sheet, such as a copper sheet. Copper sheets have a certain strength to support the sample 200, while the hardness is not too high to increase the difficulty of polishing. The support sheet 100 can also be a glass sheet or a ceramic sheet, thereby further preventing deformation and having higher flatness. It should be noted that, while ensuring that the chip 220 can be horizontally supported, the support sheet 100 should be as thin as possible to reduce the amount of subsequent polishing work.

[0071] Step 3: Cover the outer side of chip 220 with an isolation layer 300. The outer side of chip 220, as referred to here, means the surface other than the back of chip 220. The isolation layer 300 can be removed under set conditions, making it easy to take out the polished sample 200.

[0072] Step 4: Cover the outer side of the isolation layer 300 with a reinforcing layer 400. The outer side of the isolation layer 300, as referred to here, means any surface other than the back side where the isolation layer 300 is attached to the frame 230. In addition to covering the isolation layer 300, the reinforcing layer 400 is also connected to the support plate 100, for example, to the first surface 110 of the support plate 100. This connects the support plate 100, the sample 200, the isolation layer 300, and the reinforcing layer 400 into a single assembly to be polished. The reinforcing layer 400 has relatively high strength and can withstand certain vibrations and impacts; therefore, it can serve as an installation structure for connecting the assembly to be polished to the polishing equipment during the polishing process.

[0073] It should be noted that, regardless of how the reinforcing layer 400 is connected to the carrier plate 100, the second surface 120 of the carrier plate 100 must be exposed so that the second surface 120 can be used as a reference surface to contact the grinding equipment.

[0074] Step 5: Using the second surface 120 as the starting position for polishing, polishing begins towards the chip 220 until the remaining thickness of the chip 220 meets the set thickness, at which point polishing stops. Specifically, the component to be polished is connected to the drive component of the polishing equipment via the reinforcement layer 400, so that the second surface 120 faces the polishing component of the polishing equipment. Then, the position and orientation of the component to be polished are adjusted so that the second surface 120 and the polishing surface of the polishing component remain parallel and in contact with each other. Finally, the polishing equipment is started, causing the polishing components to rotate relative to each other, thus starting polishing from the second surface 120. As polishing progresses, the thickness of the component to be polished decreases, so the drive component of the polishing equipment can also drive the component to be polished to feed towards the polishing component, ensuring that the polishing surface and the surface to be polished remain in contact at all times.

[0075] In some specific embodiments, the component to be polished, formed by the carrier plate 100, the sample 200, the isolation layer 300 and the reinforcement layer 400, is a cylindrical structure, and the polishing component on the polishing equipment includes a clamping mechanism adapted to the cylinder.

[0076] The sample 200 after polishing is shown in the figure. The back side of the carrier sheet 100, frame 230, chip 220, isolation layer 300 and reinforcement layer 400 have all been removed by polishing. The remaining part of chip 220 is connected to reinforcement layer 400 through isolation layer 300.

[0077] Step 6: Based on the material of the isolation layer 300, select the appropriate method to remove the isolation layer 300, thereby separating the chip 220 from the reinforcement layer 400. At this point, the chip 220 has been polished and can be separated from the reinforcement layer 400 for subsequent testing.

[0078] The polishing solution in this embodiment has the following advantages:

[0079] First, the back of sample 200 is bonded to the first surface 110 of carrier sheet 100, and there is no adhesive between them. Therefore, sample 200 will not be skewed relative to carrier sheet 100 due to uneven adhesive thickness. At the same time, by using the second surface 120 of carrier sheet 100 as a reference surface to bond with the polishing surface of the polishing equipment, sample 200 and carrier sheet 100 will not be skewed relative to the polishing surface. In this way, the thickness of chip 220 can be made uniform after polishing.

[0080] II. When adopting Figure 1 , Figure 2 During the polishing process shown, the sides of chip 220 are exposed. As chip 220 moves relative to the polishing device, in addition to the back side being polished, the sides of chip 220 are also polished, resulting in a surface at the bottom side of chip 220 that resembles... Figure 5The chamfer 11 shown causes reflection and refraction of infrared light, resulting in unclear imaging. In this embodiment, an isolation layer 300 is wrapped around the outer surface of the chip 220 (including the aforementioned side surface). In addition to isolating the chip 220 from the enhancement layer 400, the isolation layer 300 can also protect the bottom side of the chip 220, preventing the chamfer 11 from affecting the detection results.

[0081] Third, this embodiment also includes an isolation layer 300, which is located between the chip 220 and the reinforcement layer 400. It can be removed from the chip 220 under certain conditions, thereby achieving the separation of the chip 220 and the reinforcement layer 400. Compared with the method of directly connecting the reinforcement layer 400 to the chip 220, it can significantly reduce the difficulty of separating the reinforcement layer 400 and the chip 220, and at the same time avoid leaving residues on the chip 220.

[0082] Fourth, this embodiment also includes a reinforcing layer 400. The reinforcing layer 400 has higher strength than the isolation layer 300 and can withstand stronger vibrations and impacts. Therefore, the reinforcing layer 400 covers the isolation layer 300 to form the component to be polished, and the reinforcing layer 400 is used as a mounting component to be installed in the polishing equipment. Compared with the solution of using the isolation layer 300 as a mounting component to be installed in the polishing equipment, the probability of the component to be polished breaking or fractured during the polishing process can be reduced.

[0083] The second embodiment of the present invention also proposes another polishing method, which is also applicable to the sample 200 with the frame 230. The difference between the second and third embodiments is that the isolation layer 300 in this embodiment covers not only the chip 220, but also the frame 230.

[0084] Reference Figure 6 The diagram shows the state change of sample 200 during polishing using the polishing method of the second embodiment of the present invention, including the following steps:

[0085] Step 1: Prepare a sample 200 with the molded body 210 removed. The sample 200 includes a frame 230 and a chip 220 placed on the front of the frame 230.

[0086] Step 2: Place the sample 200 on the support plate 100 so that the back of the frame 230 is in contact with the first surface 110 of the support plate 100.

[0087] Step 3: An isolation layer 300 is applied to the outer surface of the chip 220 and the outer surface of the frame 230, and the isolation layer 300 is connected to the first surface 110 of the carrier sheet 100, thereby connecting the chip 220, the frame 230 and the carrier sheet 100 together. The outer surface of the frame 230 referred to here refers to the surface other than the back surface of the frame 230 and the area on the front surface of the frame 230 that is in contact with the chip 220.

[0088] Step 4: Cover the outer side of the isolation layer 300 with the reinforcing layer 400, and expose the second surface 120 to serve as a reference surface for contact with the grinding equipment.

[0089] Step 5: Using the second surface 120 as the starting position for polishing, start polishing towards the chip 220 until the remaining thickness of the chip 220 meets the set thickness, then stop polishing.

[0090] Step 6: Based on the material of the isolation layer 300, select the appropriate method to remove the isolation layer 300, thereby separating the chip 220 from the reinforcement layer 400. At this point, the chip 220 has been polished and separated from the reinforcement layer 400, enabling subsequent testing.

[0091] In addition to the advantages of the first embodiment, the polishing solution in this embodiment also has the following advantages:

[0092] First, the area of ​​the frame 230 that extends beyond the chip 220 is usually not too large. If the sample's own frame is used as the reference surface for subsequent polishing, the isolation layer 300 needs to be limited within the frame 230 to prevent the isolation layer from overflowing to the back of the frame and affecting the levelness of the sample's polishing reference surface. However, this operation is quite difficult. The area of ​​the carrier sheet 100 is not limited and can be set to be larger. Therefore, it is easier to operate if the isolation layer 300 covers both the chip 220 and the frame 230 at the same time.

[0093] Second, the sample 200 and the carrier sheet 100 are fixed in advance by the isolation layer 300, which can prevent the sample 200 and the carrier sheet 100 from moving during the process of covering the reinforcing layer 400.

[0094] As an improvement to the second embodiment described above, the isolation layer 300 is made of a material with heat-melting properties, thereby enabling the isolation layer 300 to be formed by heating followed by curing. (Refer to...) Figure 7 The method for setting the isolation layer 300 in this embodiment includes:

[0095] Step 1: After the sample 200 is placed on the carrier 100, a solid insulating material is applied to the top of the chip 220.

[0096] Step 2: Heat the insulating material to melt it and allow it to flow downwards to the first surface 110 of the carrier sheet 100, covering the chip 220 and the frame 230. In some specific embodiments, the insulating material can be heated by a heating device 500, which can be a heating platform with a horizontal heating surface as shown in the figure. The second surface 120 of the carrier sheet 100 is in contact with the heating surface. When the heating platform is activated, heat is transferred to the insulating material through the carrier sheet 100 and the sample 200.

[0097] Step 3: Solidify the molten insulating material to form the insulating layer 300. For example, the heating device 500 can be turned off to allow the insulating material to solidify on its own, or its solidification can be accelerated by an external cooling device.

[0098] The above embodiments utilize the flow of the melted insulating material to automatically coat the chip 220 and the frame 230, eliminating the need for additional operations by the experimenters and simplifying the process.

[0099] In some specific embodiments, the material of the isolation layer 300 is paraffin wax. Paraffin wax is solid at room temperature, melts when heated, and can be re-solidified when cooled, thus meeting the aforementioned requirements of automatic flow during heating and solidification after cooling. On the other hand, paraffin wax can be dissolved in acetone, thereby achieving the removal of the isolation layer 300 without damaging the chip 220 during the removal process. After the paraffin wax dissolves, the chip 220 will automatically separate from the reinforcement layer 400.

[0100] In this embodiment, the heating temperature of paraffin wax is 100℃ to 105℃. The inventors have verified that paraffin wax has a certain degree of fluidity within this temperature range, but the fluidity is not excessive, thus allowing it to aggregate and form a structure similar to... Figure 7 The hemispherical structure shown allows the isolation layer 300 to maintain a certain thickness in order to achieve the corresponding isolation function.

[0101] The third embodiment of the present invention also proposes another polishing method, which is also applicable to the sample 200 with frame 230. The difference between the method and the first embodiment is that the reinforcing layer 400 in this embodiment covers not only the isolation layer 300, but also the other surfaces of the carrier sheet 100 except the second surface 120.

[0102] Reference Figure 8 The diagram shows the state changes of sample 200 during polishing using the polishing method of the third embodiment of the present invention, including the following steps:

[0103] Step 1: Prepare a sample 200 with the molded body 210 removed. The sample 200 includes a frame 230 and a chip 220 placed on the front of the frame 230.

[0104] Step 2: Place the sample 200 on the support plate 100 so that the back of the frame 230 is in contact with the first surface 110 of the support plate 100.

[0105] Step 3: Cover the outside of chip 220 with an isolation layer 300.

[0106] Step 4: Cover the outer side of the isolation layer 300 and the outer side of the support plate 100 except for the second surface 120 with the reinforcing layer 400, and expose the second surface 120 to serve as a reference surface for contact with the grinding equipment.

[0107] Step 5: Using the second surface 120 as the starting position for polishing, start polishing towards the chip 220 until the remaining thickness of the chip 220 meets the set thickness, then stop polishing.

[0108] Step 6: Based on the material of the isolation layer 300, select the appropriate method to remove the isolation layer 300, thereby separating the chip 220 from the reinforcement layer 400. At this point, the chip 220 has been polished and separated from the reinforcement layer 400, enabling subsequent testing.

[0109] In addition to the advantages of the first embodiment, the polishing scheme of this embodiment also has the following advantages: the carrier plate 100 is embedded in the reinforcing layer 400, which can increase the connection strength between the carrier plate 100 and the reinforcing layer 400 and prevent the carrier plate 100 from separating from the reinforcing layer 400 during the polishing process.

[0110] As an improvement to the third embodiment described above, refer to Figure 9 The method for setting the enhancement layer 400 in this embodiment includes the following steps:

[0111] Step 1: Set up a mold 600 with a receiving cavity 610. The bottom of the mold 600 is closed and the top has an opening. Place the carrier sheet 100 carrying the sample 200 into the mold 600, so that the second surface 120 is in contact with the bottom wall of the receiving cavity 610.

[0112] Step 2: Add liquid reinforcing material into the accommodating cavity 610. The liquid reinforcing material can automatically fill the accommodating cavity 610 until the liquid level is higher than the isolation layer 300.

[0113] Step 3: After the liquid reinforcing material is solidified to form the reinforcing layer 400, the reinforcing layer 400 is detached from the mold 600.

[0114] In the above embodiment, the second surface 120 is shielded by the bottom wall of the accommodating cavity 610, which can prevent the reinforcing material from adhering to the second surface 120. In addition, the reinforcing layer 400 is flush with the second surface 120, which makes it convenient to use the second surface 120 as a reference surface for polishing.

[0115] In some specific embodiments, the reinforcing layer 400 is made of resin, which has higher strength than paraffin and can withstand the impact and vibration during the polishing process.

[0116] It should be noted that the second to third embodiments described above can be combined, as shown below. Figure 10In the fourth embodiment of the present invention, the isolation layer 300 covers the outside of the chip 220 and the frame 230, the reinforcement layer 400 covers the outside of the isolation layer 300 and the other surfaces of the carrier sheet 100 except for the second surface 120, thereby having the advantages of the first to third embodiments described above.

[0117] The fourth embodiment of the present invention also proposes another polishing method, which differs from the first to third embodiments in that: this embodiment is applicable to the direct polishing of chip 220, that is, the sample 200 is a bare chip, so the previous step of removing the mold body 210 is not required.

[0118] Reference Figure 11 The diagram shows the state change of sample 200 during polishing using the polishing method of the fifth embodiment of the present invention, including the following steps:

[0119] Step 1: Prepare the 220 chip to be polished.

[0120] Step 2: Place chip 220 directly on carrier plate 100 so that the back side of chip 220 is in contact with the first surface 110 of carrier plate 100.

[0121] Step 3: Cover the outside of the chip 220 with an isolation layer 300. The isolation layer 300 is connected to the first surface 110 of the carrier sheet 100, thereby connecting the chip 220 and the carrier sheet 100 together.

[0122] Step 4: Cover the outer side of the isolation layer 300 with the reinforcing layer 400. The reinforcing layer 400 is connected to the first surface 110 of the carrier plate 100, and the second surface 120 of the carrier plate 100 is exposed to serve as a reference surface for contact with the grinding equipment.

[0123] Step 5: Using the second surface 120 as the starting position for polishing, start polishing towards the chip 220 until the remaining thickness of the chip 220 meets the set thickness, then stop polishing.

[0124] Step 6: Based on the material of the isolation layer 300, select the appropriate method to remove the isolation layer 300, thereby separating the chip 220 from the reinforcement layer 400. At this point, the chip 220 has been polished and separated from the reinforcement layer 400, enabling subsequent testing.

[0125] In addition to the advantages of the first embodiment, the sanding scheme of this embodiment does not require removing the frame 230 by sanding, thus reducing the amount of sanding work.

[0126] The sixth embodiment of the present invention also proposes another polishing method, which differs from the first to third embodiments in that: this embodiment is applicable to the direct polishing of the sample 200 with the mold 210. For example, the sample 200 is a complete power module and does not require the previous step of removing the mold 210.

[0127] Reference Figure 12 The diagram shows the state change of sample 200 during polishing using the polishing method of the fifth embodiment of the present invention, including the following steps:

[0128] Step 1: Prepare the sample 200 to be polished. The sample 200 includes a mold body 210, a chip 220 and a frame 230 located inside the mold body 210, with the chip 220 placed on the front of the frame 230.

[0129] Step 2: Place the sample 200 on the carrier sheet 100 so that the back of the sample 200 is in contact with the first surface 110 of the carrier sheet 100.

[0130] Step 3: Cover the outside of the sample 200 with an isolation layer 300. The isolation layer 300 is connected to the first surface 110 of the carrier sheet 100, thereby connecting the sample 200 and the carrier sheet 100 together.

[0131] Step 4: Cover the outer side of the isolation layer 300 with the reinforcing layer 400. The reinforcing layer 400 is connected to the first surface 110 of the carrier plate 100, and the second surface 120 of the carrier plate 100 is exposed to serve as a reference surface for contact with the grinding equipment.

[0132] Step 5: Using the second surface 120 as the starting position for polishing, start polishing towards the chip 220 until the remaining thickness of the chip 220 meets the set thickness, then stop polishing.

[0133] Step 6: Based on the material of the isolation layer 300, select the appropriate method to remove the isolation layer 300, thereby separating the chip 220 from the reinforcement layer 400. At this point, the chip 220 has been polished and separated from the reinforcement layer 400, enabling subsequent testing.

[0134] It should be noted that in the above embodiments, the polishing of sample 200 or chip 220 is accomplished using sandpaper. Specifically, the carrier sheet 100, frame 230, and chip 220 are polished using sandpaper with gradually increasing grit. The lower the grit of the sandpaper, the greater the amount removed in a single pass, the faster the polishing speed, and the rougher the polished surface. Conversely, the higher the grit of the sandpaper, the smaller the amount removed in a single pass, the slower the polishing speed, and the smoother the polished surface. Based on the above, when polishing the carrier sheet 100, since it is far from the chip 220, a lower grit sandpaper can be used for rapid polishing. When polishing the frame 230, since the frame 230 is adjacent to the chip 220, a relatively higher grit sandpaper is used to ensure a certain polishing speed while avoiding damage to the chip 220 when polishing close to it. When polishing the chip 220, the highest grit sandpaper is used to ensure the polishing quality of the surface. By using different sandpapers at different stages of sanding, both sanding speed and sanding quality can be balanced.

[0135] For example, when polishing the carrier plate 100, 180-grit sandpaper can be used; when polishing the frame 230, 400-grit sandpaper can be used; and when polishing the chip 220, 800-grit sandpaper can be used.

[0136] It should be noted that the polishing stage can be determined based on the thickness of the polished surface or by visual observation.

[0137] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A chip polishing method, characterized in that, Includes the following steps: Prepare a sample to be processed and a rigid carrier sheet. The sample includes a chip and a frame. The chip is connected to the front side of the frame. The carrier sheet has a first surface and a second surface that are disposed opposite to each other. The back side of the frame is attached to the first surface of the support piece; An isolation layer is covered at least on the outer side of the chip, and a reinforcement layer is covered on the outer side of the isolation layer, and at least the second surface of the carrier sheet is exposed; Polishing begins from the second surface and proceeds toward the chip until the chip retains a predetermined thickness. Remove the isolation layer to separate the sample from the reinforcement layer.

2. The chip polishing method according to claim 1, characterized in that, The isolation layer covers all outer surfaces of the frame except the back side, and the isolation layer is connected to the first surface of the carrier piece.

3. The chip polishing method according to claim 2, characterized in that, The method for setting the isolation layer includes: After the sample is placed on the carrier sheet, a solid insulating material is applied to the top of the chip; The insulating material is heated to melt it and allow it to flow downwards to the carrier sheet, thereby covering the chip and the frame. The molten insulating material is solidified to form the insulating layer.

4. The chip polishing method according to claim 3, characterized in that, The insulating layer is made of paraffin wax and is heated to 100°C to 105°C.

5. The chip polishing method according to claim 1, characterized in that, The reinforcing layer covers all outer surfaces of the support sheet except for the second surface.

6. The chip polishing method according to claim 5, characterized in that, The method for setting the enhancement layer includes: A mold with a receiving cavity is provided, and the carrier piece carrying the sample is placed in the mold so that the second surface is in contact with the bottom wall of the receiving cavity; Add liquid reinforcing material into the accommodating cavity until the liquid level is higher than the insulating layer; The liquid reinforcing material is solidified to form the reinforcing layer.

7. The chip polishing method according to claim 6, characterized in that, The reinforcing layer is made of resin.

8. The chip polishing method according to claim 1, characterized in that, The carrier plate, the frame, and the chip are polished separately using sandpaper with gradually increasing grit.

9. A chip polishing method, characterized in that, Includes the following steps: Prepare a carrier sheet and a sample to be processed. The sample includes a mold, a chip and a frame located within the mold, the chip being connected to the front side of the frame, and the carrier sheet having a first surface and a second surface disposed opposite to each other. The back side of the molded body is attached to the first surface of the carrier sheet; An isolation layer is wrapped around the outside of the molded body, and a reinforcing layer is wrapped around the outside of the isolation layer, so that at least the second surface of the carrier sheet is exposed; Polishing begins from the second surface and proceeds toward the chip until the chip retains a predetermined thickness. Remove the isolation layer to separate the sample from the reinforcement layer.

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