A method for grinding a semiconductor package product

Abstract

This application relates to a method for grinding semiconductor packaging products. Some embodiments of this application provide a grinding method for semiconductor packaging products, which includes the following steps: obtaining an X-ray image of a sample through an X-ray imager to confirm the grinding position; placing the sample into a potting module and pouring in a colloid to solidify and form a cured colloid-sample composite; marking a reference line for the position to be ground on the cured colloid-sample composite based on the grinding position of the X-ray image through a laser machine; and grinding the marked cured colloid-sample composite. The grinding method of this application can improve the accuracy and efficiency of semiconductor packaging grinding, and at the same time reduce the damage to non-grinding areas during the grinding process, thereby optimizing the efficiency and quality of the detection process.

Description

Technical Field

[0001] This application relates to semiconductor package inspection, and more particularly to a method for grinding semiconductor package products. Background Art

[0002] In the semiconductor packaging process, the inspection of semiconductor package products is a crucial step for checking any defects or errors in the packaged chips to ensure the subsequent normal operation of the products.

[0003] For all chip products that need to be ground to expose the internal structure for failure cause analysis or structural analysis, the currently adopted grinding method is to detect the internal structure or abnormal conditions of the product through X-ray (X-Ray), and determine the grinding position based on this. Subsequently, the product is ground by manually grinding while observing the internal structure of the product by comparing with the X-ray image under a microscope. This grinding method has inaccurate positioning of the grinding position, low grinding efficiency, and problems such as grinding angle deviation or excessive grinding resulting in the disappearance of the position to be ground. For example, the wire bond of the ground sample is worn off.

[0004] In view of this, it is necessary to research and improve the grinding process of semiconductor package products to improve the efficiency and accuracy of chip inspection. Summary of the Invention

[0005] Embodiments of the present application provide a method for grinding semiconductor package products to solve at least one problem existing in the related art to at least some extent.

[0006] According to one aspect of the present application, some embodiments of the present application provide a method for grinding semiconductor package products, which includes the following steps:

[0007] Obtain an X-ray image of the sample through an X-ray imager to confirm the grinding position;

[0008] Place the sample into a potting module and pour in a colloid to solidify and form a cured colloid-sample composite;

[0009] Mark a reference line for the position to be ground on the cured colloid-sample composite through a laser machine based on the grinding position in the X-ray image; and

[0010] Grind the marked cured colloid-sample composite.

[0011] In some embodiments, the step of placing the sample into a potting module and pouring in a colloid to solidify and form a cured colloid-sample composite further includes:

[0012] Pour in a part of the colloid in advance to cover the bottom of the potting module; and

[0013] Place the sample into the potting module and let it settle to the bottom of the potting module.

[0014] In some embodiments, the step of placing the sample into the potting module and pouring in a colloid to cure and form a cured colloid - sample composite further comprises:

[0015] Place the top surface of the sample into the potting module in an inverted - down manner, where the top surface of the sample faces the bottom of the potting module.

[0016] In some embodiments, the colloid comprises: a polymer resin and a curing agent used in combination with the polymer resin. The mass ratio of the polymer resin to the curing agent is 3:1, and the colloid is substantially colorless and transparent after curing.

[0017] In some embodiments, the polymer resin comprises one or more of epoxy resin, polyester resin, and acrylate.

[0018] In some embodiments, the step of marking a reference line for the position to be ground on the cured colloid - sample composite by a laser machine based on the X - ray image further comprises:

[0019] Locate the cured colloid - sample composite in the laser machine according to the X - ray image;

[0020] Determine the position to be ground on the cured colloid - sample composite on the X - ray image; and

[0021] Laser - etch the reference line for the position to be ground on the corresponding position to be ground on the cured colloid - sample composite according to the position to be ground on the X - ray image.

[0022] In some embodiments, the step of marking the position to be ground on the cured colloid - sample composite by a laser machine based on the X - ray image further comprises:

[0023] After laser - etching the reference line for the position to be ground, further mark an auxiliary line along the reference line for the position to be ground.

[0024] In some embodiments, the step of grinding the marked cured colloid - sample composite further includes:

[0025] Rough - grind the cured colloid - sample composite until the wire frame is exposed;

[0026] Grind the cured colloid - sample composite until the chip edge is exposed;

[0027] Fine grind the cured glue - sample composite near the reference line of the position to be ground and / or the auxiliary line, e.g., grind the cured glue - sample composite to within 50 microns of the reference line of the position to be ground and / or the auxiliary line.

[0028] In some embodiments, the step of grinding the marked cured glue - sample composite further includes:

[0029] Fine grind the cured glue - sample composite that has been ground to the reference line of the position to be ground and / or the auxiliary line, and rinse the grinding surface during the fine grinding.

[0030] In some embodiments, after the grinding step, it further includes:

[0031] Polish the surface of the ground cured glue - sample composite.

[0032] The grinding method of the present application imports the X - ray image of the sample to be ground into the laser machine table to mark the reference line of the position to be ground at the corresponding position of the sample to be ground. The reference line of the position to be ground can effectively locate the grinding position of the sample to be ground, thereby achieving precise grinding of the defective area of the sample and improving the efficiency of the grinding process at the same time. In some embodiments, the step of pre - injecting glue can completely coat the sample to be ground in the colloid, and then form a cured glue - sample composite with a stable structure, greatly reducing the situation of the sample cracking or peeling during the grinding process. At the same time, the sample that slowly sinks to the bottom can form a flat and clear encapsulation surface on the bottom surface of the cured glue - sample composite, which highly coincides with the X - ray image, so as to provide a highly accurate reference line of the position to be ground in the subsequent laser marking process to define the surface to be ground of the sample.

[0033] The grinding method of the present application can improve the accuracy and efficiency of semiconductor package grinding, and at the same time reduce the damage to non - grinding areas during the grinding process, thereby optimizing the efficiency and quality of the detection process.

[0034] Additional aspects and advantages of the embodiments of the present application will be partially described, shown, or elucidated through the implementation of the embodiments of the present application in the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings necessary for describing the embodiments of the present application or the prior art will be briefly described below to facilitate the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. Those skilled in the art can obtain the drawings of other embodiments according to the structures illustrated in these drawings.

[0036] Figure 1is a micrograph of the ground surface of a semiconductor package product according to the prior art.

[0037] Figure 2 is a flowchart of a method for grinding a semiconductor package product according to some embodiments of the present application.

[0038] Figure 3A and 3B is a schematic structural view of a cured glue-sample composite according to some embodiments of the present application.

[0039] Figures 4A to 4C is a schematic view of a glue filling process according to some embodiments of the present application.

[0040] Figure 5 is a micrograph of the ground surface of a semiconductor package product according to an exemplary embodiment of the present application. Detailed Description of the Embodiments

[0041] Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application.

[0042] Unless otherwise expressly specified, the following terms used herein have the meanings set forth below.

[0043] As used herein, the terms "substantially", "essentially", "substantially", and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances where the event or circumstance occurs precisely as well as instances where the event or circumstance occurs very nearly. For example, when used in conjunction with a numerical value, the term can refer to a range of variation of less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two numerical values is less than or equal to ±10% of the average value of the said value (such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two numerical values can be considered to be "substantially" the same.

[0044] In the field of semiconductor packaging, for failure analysis or structural analysis of defects in packaged chips, it is often necessary to cut or grind the packaged chips to expose their defective surfaces for further microscopic observation and scanning electron microscope analysis and other techniques. The grinding process is a very critical step in chip failure analysis, which can provide analysts with accurate observation and analysis of the defects and failure causes inside the packaged chips.

[0045] At present, the grinding method is to pre-detect the internal structure or abnormalities of the product through X-rays, and determine the grinding position (the grinding position is the surface to be detected) based on this, so that the internal structure or abnormalities corresponding to the grinding position can be exposed by grinding for subsequent analysis. For the grinding of encapsulated chips, one side of the product needs to be vertically fixed on the base of the potting mold, and then potting is carried out. After the colloid is cured, grinding is carried out to position the vertical surface of the product. During the grinding process, the inspector needs to observe the vertical surface of the product at the current grinding position with a microscope while grinding, compare it with the X-ray image to determine whether the current grinding position and direction are accurate, and adjust the grinding angle according to the grinding position specified in the X-ray image.

[0046] However, this grinding method has inaccurate positioning of the grinding position, low grinding efficiency, and the problem that the wire arc of the ground sample is ground off due to excessive grinding. As Figure 1 shown, the ground surface by manual grinding often cannot be aligned with the defect position indicated by the X-ray image. Even in severe cases, excessive grinding will cause damage to the non-defect area of the product, resulting in the inability to identify the actual failure cause in failure analysis, or the sample being damaged and unable to be analyzed, thereby reducing the efficiency of detection and analysis.

[0047] In view of the above problems, the embodiments of the present application provide a method for grinding semiconductor encapsulated products. Based on the defect position or structure of the semiconductor encapsulated product in the X-ray image, the X-ray image is input into the laser machine tool, and the laser machine tool marks the reference line of the position to be ground on the cured sample. The reference line of the position to be ground can effectively locate the specified position of the semiconductor encapsulated product, and the grinding process is carried out until the reference line of the position to be ground can provide a highly accurate grinding surface. The method of the present application can improve the defect that the existing grinding process cannot effectively and accurately locate the defect surface, greatly improve the accuracy of failure analysis and structural analysis, and can significantly improve the efficiency of the grinding process.

[0048] Figure 2 is a flowchart of a method for grinding semiconductor encapsulated products according to some embodiments of the present application.

[0049] As Figure 2 shown, a method for grinding semiconductor encapsulated products of the present application includes the following steps:

[0050] 101 Obtain the X-ray image of the sample through an X-ray imager to confirm the grinding position;

[0051] 102 Place the sample into the potting module and pour in the colloid to cure and form a cured colloid-sample composite;

[0052] 103 The laser machine marks the grinding position reference line of the cured glue-sample composite based on the grinding position of the X-ray image; and

[0053] 104 The marked cured glue-sample composite is ground by a grinding machine.

[0054] The sample can be any suitable semiconductor packaging product in the art without limitation. Based on the disclosure of this application, those skilled in the art can adjust the size of the glue injection mold according to different size requirements of the sample.

[0055] In step 101, the definition of defects of the grinding sample by the X-ray imager is a conventional operation in the art. The X-ray imager can be any suitable instrument or commercial product in the art without limitation. In some embodiments, the X-ray imager images in the direction facing the top surface of the grinding sample, and the imaging direction of the X-ray image is perpendicular to the top surface of the grinding sample to facilitate subsequent alignment and positioning of the grinding position reference line of the sample. In some embodiments, the positioning of the grinding surface for the defects on the X-ray image can be adjusted according to actual analysis needs without limitation.

[0056] In step 102, the cured glue-sample composite formed by glue injection and curing can facilitate the fixation and movement of the sample during the grinding process. In some embodiments, the colloid includes: a polymer resin and a curing agent used in combination with the polymer resin. The mass ratio of the polymer resin to the curing agent is 3:1. The principle of hardening of the polymer resin is that in a molecular structure of the polymer resin, there are two or more epoxy groups, and under appropriate chemical reagents and suitable conditions, a three-dimensional cross-linked cured compound can be formed, thereby achieving the curing effect. In some embodiments, the colloid can be selected to form a transparent and colorless polymer resin after curing. In some embodiments, the polymer resin includes one or more of epoxy resin, polyester resin, and acrylate resin.

[0057] The curing agent can be selected and matched with any suitable curing agent in the art according to the type of resin. In some embodiments, the curing agent includes amine curing agents, anhydride curing agents, or latent curing agents. In some embodiments, the curing agent is an amine curing agent, and the amine curing agent includes one or more of polyamide-based, aliphatic amine-based, aromatic amine-based, polyether amine-based, and imidazole-based. In some embodiments, the curing agent is an anhydride curing agent, and the anhydride curing agent includes one or more of aromatic anhydrides, aliphatic anhydrides, and alicyclic anhydrides. In some embodiments, the curing agent is a latent curing agent, and the latent curing agent includes one or more of dicyandiamide, 594, 596 curing agents, and boron trichloride-monoethylamine complex.

[0058] In some embodiments, the colloid is gently poured into the potting mold along the walls of the mold. After completely covering the polished sample, it is left to stand for about 4 hours to allow the sample to cure and bond with the colloid. In some embodiments, heating can be performed through the curing environment to accelerate curing. In some embodiments, the ambient temperature of the curing process is about 80°C ± 5°C. Within the above-mentioned curing temperature range, voids in the colloid can be avoided while reducing the curing time to about 1.5 hours to about 2 hours.

[0059] In some embodiments, the step of placing the sample into the potting module and pouring in the colloid to cure and form a cured colloid-sample composite further comprises: placing the top surface of the sample into the potting module in an inverted-downward manner, where the top surface of the sample faces the bottom of the potting module.

[0060] Figure 3A and 3B is a schematic structural diagram of a cured colloid-sample composite according to some embodiments of the present application. As Figure 3A and 3B shown, after taking out the cured colloid-sample composite 201 formed by placing the top surface 202T of the sample 202 into the potting module in an inverted-downward manner, the sample can be fixed at the bottom of the cured colloid-sample composite 201, and the top surface 202T of the sample 202 can be parallel to the bottom surface 201B of the cured colloid-sample composite 201, facilitating the alignment of the top surface 202T of the sample 202 with the X-ray image to locate the reference line for the position to be polished and reducing the distortion or deviation generated during positioning. In some embodiments, the top surface 202T of the sample 202 and the bottom surface 201B of the cured colloid-sample composite 201 are substantially coplanar, which is beneficial for the subsequent alignment and positioning of the sample during the polishing process.

[0061] The bottom area size of the potting mold is slightly larger than the size of the top surface of the sample to ensure that the sample can be placed parallel to the bottom of the potting mold.

[0062] Figures 4A to 4C is a schematic diagram of the potting process according to some embodiments of the present application.

[0063] As Figures 4A to 4C shown, step 102 further comprises: pre-pouring a part of the colloid 301 to cover the bottom of the potting module 302; placing the sample 202 into the potting module 302 and allowing it to settle to the bottom of the potting module 302; and continuing to pour in the colloid 301 until the sample 202 is completely covered. By pre-pouring a part of the colloid, a layer of colloid can exist between the sample and the bottom of the potting module. When the colloid cures, a thin film-like protective layer can be formed on the surface of the sample, improving the fixation of the sample and preventing the sample from falling off or shifting from the fixing colloid during polishing.

[0064] In step 103, the X-ray image of the sample is imported into the laser machine table, and the position reference line to be ground is marked on the bottom surface of the cured glue-sample composite (corresponding to the top surface of the sample) based on the defect position in the X-ray image. The ground line with a linear mark can be applicable to the failure analysis of the grinding of a single surface. Without departing from the spirit of the present application, those skilled in the art can select a suitable grinding mark according to actual needs, and it is not limited to the linear position reference line to be ground. For example, if the defect structure is an irregular arc structure or a curved structure, the marked illustration to be ground can be irregular or curved.

[0065] In some embodiments, step 103 further includes: positioning the cured glue-sample composite in the laser machine table according to the X-ray image; determining the position to be ground of the cured glue-sample composite on the X-ray image; and laser-etching the grinding reference line on the corresponding position to be ground of the cured glue-sample composite according to the position to be ground on the X-ray image. The length or thickness of the position reference line to be ground can be adjusted according to the dimensional requirements of actual operation, and is not limited thereto.

[0066] In some embodiments, the positioning of the X-ray image can be performed by aligning the corresponding corners of the sample part or by coinciding with the top surface of the sample. In some embodiments, the positioning of the X-ray image can be performed by aligning the characteristic marks of the sample.

[0067] In some embodiments, the step of marking the position to be ground of the cured glue-sample composite based on the X-ray image by the laser machine table further includes: after laser-etching the position reference line to be ground, further marking the auxiliary line along the position reference line to be ground. The drawing of the auxiliary line can optimize the alignment of the subsequent grinding process and improve the efficiency and accuracy of grinding.

[0068] In step 104, without damaging the surface of the product, the grinding process can be a common grinding process in the art. In some embodiments, step 104 further includes: rough-grinding the cured glue-sample composite until the wire frame is exposed; grinding the cured glue-sample composite until the chip edge is exposed; and fine-grinding the cured glue-sample composite close to the position reference line to be ground and / or the auxiliary line, such as: grinding the cured glue-sample composite to be close to within 50 microns of the position reference line to be ground and / or the auxiliary line.

[0069] In some embodiments, step 104 further includes: finely grinding the cured glue-sample composite close to the position reference line to be ground and / or the auxiliary line until the surface to be detected is exposed, and using a solvent, such as deionized water, during the fine grinding to wash away the debris generated on the grinding surface, thereby preventing the debris from scratching the grinding surface during the grinding process. At the same time, the grinding surface can be kept clean, which is convenient for subsequent microscopic observation.

[0070] In some embodiments, for rough grinding, sandpaper with a grit size of 100 to 240 or an equivalent grinding surface is used; for grinding, sandpaper with a grit size of 800 to 1500 or an equivalent grinding surface is used; for fine grinding, sandpaper with a grit size of 2000 to 2500 or an equivalent grinding surface is used; and for ultra-fine grinding, sandpaper with a grit size of over 4000 or an equivalent grinding surface is used.

[0071] In some embodiments, the direction of the grinding surface is substantially perpendicular to the top surface of the sample. In some embodiments, the angle between the grinding surface and the top surface of the sample can be adjusted according to actual analysis needs to obtain grinding surfaces at different angles.

[0072] In some embodiments, after the grinding step, it further includes: polishing the surface of the ground cured glue-sample composite. Without departing from the spirit of the present application, the polishing process can be a common polishing process in the art and is not limited thereto. In some embodiments, the polishing process includes: using a polishing liquid, such as diamond suspension or SiO2 polishing liquid, etc., and cooperating with a polishing cloth to polish the surface of the ground cured glue-sample composite until there are no scratches on the surface of the cured glue-sample composite under a microscope with a magnification of 500 times.

[0073] To more clearly illustrate the grinding method for semiconductor packaging products in the embodiments of the present application, the following provides a specific exemplary embodiment for packaged chips:

[0074] Confirm the grinding position: Photograph the top surface of the packaged chip through an X-ray imager to obtain an X-ray image of the top surface of the packaged chip; define the grinding position according to the position of the defect structure in the X-ray image.

[0075] Sample glue injection and curing: The colloid is formed by mixing epoxy resin and a curing agent in a ratio of 3:1. Pour in a part of the colloid in advance. After the colloid covers the bottom of the glue injection mold, place the top surface of the packaged chip into the glue injection mold in the direction facing the bottom of the glue injection mold. Then, use a tool to make the packaged chip sink to the bottom of the glue injection module. Subsequently, pour in the remaining colloid to cover the bottom surface of the placed packaged chip. Then, let it stand for 4 hours to complete curing, and then demold to obtain a cured glue-packaged chip composite.

[0076] Laser grinding position: Place the cured glue - encapsulated chip composite with the bottom surface facing up into the laser machine tool. Adjust the microscope lens to an appropriate magnification. Then import the X - ray image into the operating software of the laser machine tool to make the X - ray image the same size as the product. Drag the image to coincide with the top surface of the encapsulated chip, ensuring that the four corners of the encapsulated chip completely coincide with the four corners of the X - ray image to position the encapsulated chip. According to the grinding position on the X - ray image, operate the operating software of the laser machine tool to select a straight - line pattern. After aligning the straight line with the grinding position, perform laser marking to mark the reference line of the position to be ground on the top surface of the encapsulated chip.

[0077] Grinding: Place the marked cured glue - encapsulated chip composite into a grinding instrument. Use 180 - mesh sandpaper to coarsely grind the colloid part of the cured glue - encapsulated chip composite until the wire frame is exposed. Use 1200 - mesh sandpaper to grind the cured glue - encapsulated chip composite until the edge of the encapsulated chip is exposed. Use 2500 - mesh sandpaper to grind the cured glue - encapsulated chip composite until it touches the reference line of the position to be ground. And use 4000 - mesh sandpaper to finely grind the cured glue - encapsulated chip composite that has been ground to the reference line of the position to be ground to the surface to be detected, while rinsing the grinding surface with deionized water, where the grinding surface is perpendicular to the top surface of the encapsulated chip.

[0078] Figure 5 It is a microscopic image of the ground surface of a semiconductor - encapsulated product under a scanning electron microscope according to an exemplary embodiment of the present application.

[0079] As Figure 5 shown, the grinding method of the semiconductor - encapsulated product in the embodiment of the present application can greatly improve the positioning accuracy of the ground surface of the semiconductor - encapsulated product, clearly present the defective part of the encapsulated chip, and optimize the failure analysis and structural analysis of the product. Compared with the images of the prior art, the grinding method of the present application can improve the precision and efficiency of semiconductor - encapsulation grinding, while reducing the damage to non - grinding areas during the grinding process, thereby optimizing the efficiency and quality of the detection process.

[0080] References throughout this specification to "an embodiment", "some embodiments", "one embodiment", "another illustration", "an illustration", "a specific illustration", or "a partial illustration" mean that at least one embodiment or illustration in this application includes the specific features, structures, materials, or characteristics described in that embodiment or illustration. Thus, descriptions that occur throughout this specification, such as "in some embodiments", "in embodiments", "in one embodiment", "in another illustration", "in an illustration", "in a specific illustration", or "an illustration", are not necessarily references to the same embodiment or example in this application. In addition, the specific features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or illustrations.

[0081] Although the illustrative embodiments have been shown and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the application, and that changes, substitutions, and modifications to the embodiments can be made without departing from the spirit, principles, and scope of the application.

Claims

1. A grinding method for a semiconductor packaging product, comprising the following steps: A. Obtain an X-ray image of a sample through an X-ray imager to confirm the grinding position; B. Place the sample into a potting module and pour in a colloid to cure and form a cured colloid-sample composite, wherein the top surface of the sample is placed into the potting module in an inverted-downward manner, wherein the top surface of the sample faces the bottom of the potting module, and wherein step B further comprises the following steps: Pre-pour a part of the colloid to cover the bottom of the potting module; and Place the sample into the potting module and let it settle to the bottom of the potting module; C. Based on the grinding position in the X-ray image, mark a reference line for the position to be ground of the cured colloid-sample composite on the bottom surface of the cured colloid-sample composite by a laser machine, the bottom surface corresponding to the top surface of the sample; and D. Grind the marked cured colloid-sample composite, wherein the direction of the grinding surface is substantially perpendicular to the top surface of the sample.

2. The method according to claim 1, wherein the colloid comprises: a polymer resin and a hardener used in combination with the polymer resin, the mass ratio of the polymer resin to the hardener is 3:1, and the colloid is substantially colorless and transparent after curing.

3. The method according to claim 2, wherein the polymer resin comprises one or more of epoxy resin, polyester resin, and acrylate.

4. The method according to claim 1, wherein step C further comprises: Position the cured colloid-sample composite in the laser machine according to the X-ray image; Determine the position to be ground of the cured colloid-sample composite on the X-ray image; and Laser etch the reference line for the position to be ground on the corresponding position to be ground of the cured colloid-sample composite according to the position to be ground on the X-ray image.

5. The method according to claim 4, wherein step C further comprises: After the laser etching of the reference line for the position to be ground, further mark an auxiliary line along the reference line for the position to be ground.

6. The method according to claim 5, wherein step D further comprises: Rough grind the cured colloid-sample composite until the lead frame is exposed; Grind the cured colloid-sample composite until the chip edge is exposed; Fine grind the cured colloid-sample composite close to the reference line for the position to be ground and / or the auxiliary line; and Perform fine grinding on the cured colloid-sample composite until the surface to be detected is exposed, and use a solvent to rinse the grinding surface during the fine grinding.

7. The method according to claim 1, further comprising, after step D: Perform a polishing treatment on the surface of the ground cured colloid-sample composite.

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