Ball mounting salient point forming method and system, intelligent terminal and storage medium
By forming special-shaped ball-planting bumps on the integrated circuit wafer and controlling the bump size using the transition layer and flux, the problem of excessive packaging size is solved, and more efficient packaging efficiency and smaller wafer size are achieved.
Patent Information
- Application Number
- CN202411685853.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-23
- Publication Date
- 2025-03-14
AI Technical Summary
In the prior art, the requirement of the spacing of the ball planting bumps limits the packaging size of the integrated circuit wafer, resulting in a larger package size.
By forming a special-shaped ball-planting bump on the integrated circuit wafer, the size of the bump is controlled using a transition layer and flux to ensure that the bump area remains unchanged to reduce the wafer size.
While ensuring that the convex area remains unchanged, the size of the integrated circuit wafer in one direction is reduced, the packaging efficiency is improved, and more chips can be produced at one time.
Smart Images
Figure CN119626924A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of chip packaging technology, and in particular to a method and system for forming ball bumps, an intelligent terminal, and a storage medium. Background Art
[0002] In chip manufacturing, the ball planting process refers to the precise placement of solder balls or tin balls on the chip's pads during the semiconductor packaging process to form bumps for electrical connection and mechanical fixation.
[0003] The related technology requires coating an integrated circuit wafer with a transition layer to ensure the adhesion of the solder balls. The solder balls are then placed on the transition layer. After placement, the solder balls are heated to melt and bond with the transition layer, forming bumps. Finally, the integrated circuit wafer is cut and mounted.
[0004] With respect to the above-mentioned related technologies, the inventors believe that the limitation of the bump pitch requirement affects the package size of the integrated circuit wafer, resulting in a larger package size. Summary of the Invention
[0005] In order to form irregular-shaped ball bumps and thus reduce the packaging size of a wafer, the present application provides a ball bump forming method, system, intelligent terminal, and storage medium.
[0006] In a first aspect, the present application provides a method for forming a ball bump, which adopts the following technical solution: A method for forming a ball bump includes: A first dielectric layer is covered on the integrated circuit wafer, wherein the first dielectric layer is provided with a first opening, and the first opening exposes the chip electrode of the integrated circuit wafer; forming a redistribution layer at the first opening; A second dielectric layer is covered on the redistribution layer, wherein a second opening is provided on the second dielectric layer, and the second opening exposes a portion of the redistribution layer; Transferring the transition layer having a bump pattern on the second opening, wherein the bump pattern is a special shape; Through the ball planting process, ball planting bumps are formed on the transition layer, and the height of the ball planting bumps is less than a preset height.
[0007] By adopting the above technical solution, special-shaped ball bumps are formed on the integrated circuit wafer. While ensuring that the bump area remains unchanged, the size of the integrated circuit wafer in one direction can be reduced. On the integrated circuit wafer of the same size, by setting special-shaped ball bumps, more chips can be produced at one time, thereby improving packaging efficiency.
[0008] Optionally, printing flux on the transition layer; placing a solder ball on the flux, wherein the size of the solder ball is smaller than the size of the transition layer; Through the reflow process, the solder balls are melted so that the solder corresponding to the solder balls fills the transition layer. The reflow process is performed at a preset temperature. Through the reflow process, the melted solder is solidified to form ball bumps.
[0009] By adopting the above technical solution, when forming the ball bump, the size of the ball bump is controlled by the transition layer and the soldering flux, so that the effective area of the ball bump can meet the design requirements.
[0010] Optionally, detect the actual thickness of the flux at various locations; Comparing the actual thickness with a preset thickness interval to screen out abnormal areas, where the endpoints of the preset thickness interval include a preset minimum thickness value and a preset maximum thickness value, and the abnormal areas are concave areas or convex areas; In the case where the abnormal area is a concave area, the target position is determined within the abnormal area according to the shape of the abnormal area; Place the solder ball at the target position; The solder balls are melted at a first temperature through a reflow process, where the first temperature is greater than a preset temperature; In the case where the abnormal area is a convex area, the target position is determined within the circumference of the abnormal area according to the shape of the abnormal area; Place the solder ball at the target position; Through the reflow process, the solder balls are melted at a second temperature, where the second temperature is lower than a preset temperature.
[0011] By adopting the above technical solution, different methods are set for remedial treatment of abnormal areas of the flux, so that the abnormal areas will not affect the shape and size of the ball bumps, ensuring that the quality of the ball bumps meets the design requirements.
[0012] Optionally, when the abnormal region belongs to a sunken region and there are at least two abnormal regions, a clustering operation is performed on the abnormal regions to obtain clustered abnormal regions; Determining whether the distance between clustered abnormal regions is less than a first preset distance; If so, the target location is set between the clustered anomaly areas; Place solder balls at target locations, where the size of the solder balls is standard; Monitor the flow of solder balls during the reflow process; When the solder balls flow to the cluster abnormal area, the cluster abnormal area is heated by laser, and the heating temperature of the laser is a preset first heating temperature; If not, then set the target location within each clustered anomaly area; A solder ball is placed at each target location, the size of the solder ball being smaller than the standard size.
[0013] By adopting the above technical solution, when the abnormal area belongs to a recessed area, the abnormal area is clustered to obtain clustered abnormal areas, and a corresponding solution is selected for processing based on the distance between the clustered abnormal areas, thereby ensuring that the ball bumps generated on the recessed area meet the design requirements and improving the yield rate of packaged integrated circuit wafers.
[0014] Optionally, when the abnormal region is a raised region and there are at least two abnormal regions, the target position is determined based on the position distribution of the abnormal regions on the solder flux, and the distance from the target position to each abnormal region is the same; Place a solder ball at a target location, the size of the solder ball being a standard size; Monitor the flow of solder balls; In the reflow process, the abnormal area is heated by laser, and the heating temperature of the laser is a preset second heating temperature; When the distance between the solder ball and the abnormal area is less than a second preset distance, heating of the abnormal area is stopped.
[0015] By adopting the above technical solution, when the abnormal area is a raised area, the target position for placing the solder ball is determined according to the position distribution of the abnormal area on the flux, and the abnormal area is heated during the reflow process to reduce the thickness of the abnormal area, so that the ball bumps generated on the raised area meet the design requirements, thereby improving the yield rate of the packaged integrated circuit wafer.
[0016] Optionally, in the case where the abnormal region includes a convex region and a concave region, the shortest distance between the convex region and the concave region is calculated; If the shortest distance is less than the third preset distance, calculating the convex volume of the convex area and the concave volume of the concave area; During the reflow process, the convex area is heated in the order from the end close to the concave area to the end farthest from the convex and concave areas; If the volume of the protrusion is larger than the volume of the depression, then when it is detected that the volume of the depression is smaller than the first preset volume, heating of the protrusion area is stopped; If the volume of the protrusion is smaller than the volume of the depression, the protrusion area and the depression area are heated when it is detected that the volume of the protrusion is smaller than the second preset volume.
[0017] By adopting the above technical solution, when the abnormal area includes both a raised area and a recessed area, the corresponding processing method will be selected to solve the abnormal area according to the volume of the two abnormal areas, so that the ball bumps generated on the raised area meet the design requirements and improve the packaging efficiency of the integrated circuit wafer.
[0018] Optionally, obtaining the position distribution of abnormal areas on the flux; determining abnormal printing parameters according to the position distribution, the abnormal printing parameters including at least one of the number of printing times, the printing direction, and the coating amount of a single printing; Update abnormal printing parameters; printing soldering flux according to abnormal printing parameters to obtain updated soldering flux; The abnormal printing parameters are updated according to the updated flux thickness and position distribution.
[0019] By adopting the above technical solution, the abnormal printing parameters are updated according to the position distribution of the abnormal areas on the flux, and the occurrence of abnormal areas can be reduced in the subsequent printing process of the abnormal areas.
[0020] In a second aspect, the present application provides a ball bump forming system, which adopts the following technical solution: A ball bump forming system includes: an acquisition module for acquiring an integrated circuit wafer, a solder flux, a solder ball, an actual thickness, a preset thickness range, a first preset distance, a second preset distance, a third preset distance, a first heating temperature, a second heating temperature, a first preset volume, and a second preset volume; A memory for storing a program of any one of the above-mentioned ball bump forming methods; The program in the memory can be loaded and executed by the processor to implement any of the above-mentioned ball bump forming methods.
[0021] By adopting the above technical solution, special-shaped ball bumps are formed on the integrated circuit wafer. While ensuring that the bump area remains unchanged, the size of the integrated circuit wafer in one direction can be reduced. On the integrated circuit wafer of the same size, by setting special-shaped ball bumps, more chips can be produced at one time, thereby improving packaging efficiency.
[0022] In a third aspect, the present application provides a smart terminal that adopts the following technical solution: An intelligent terminal includes a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and execute any one of the above methods.
[0023] By adopting the above technical solution, special-shaped ball bumps are formed on the integrated circuit wafer. While ensuring that the bump area remains unchanged, the size of the integrated circuit wafer in one direction can be reduced. On the integrated circuit wafer of the same size, by setting special-shaped ball bumps, more chips can be produced at one time, thereby improving packaging efficiency.
[0024] In a fourth aspect, the present application provides a computer storage medium capable of storing a corresponding program, which is convenient for forming irregularly shaped bumps, thereby reducing the package size of a wafer, and adopts the following technical solution: A computer-readable storage medium stores a computer program that can be loaded by a processor and execute any of the above-mentioned methods for forming implant ball bumps.
[0025] By adopting the above technical solution, special-shaped ball bumps are formed on the integrated circuit wafer. While ensuring that the bump area remains unchanged, the size of the integrated circuit wafer in one direction can be reduced. On the integrated circuit wafer of the same size, by setting special-shaped ball bumps, more chips can be produced at one time, thereby improving packaging efficiency.
[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. Forming irregular ball bumps on the integrated circuit wafer can reduce the size of the integrated circuit wafer in one direction while ensuring that the bump area remains unchanged. On the same size integrated circuit wafer, by setting irregular ball bumps, more chips can be produced at one time, thereby improving packaging efficiency. 2. When forming the ball bumps, the size of the ball bumps is controlled by the transition layer and flux so that the effective area of the ball bumps can meet the design requirements; 3. When the abnormal area belongs to a recessed area, the abnormal area is clustered to obtain clustered abnormal areas, and the corresponding solution is selected for processing based on the distance between the clustered abnormal areas to ensure that the ball bumps generated on the recessed area meet the design requirements and improve the yield rate of the packaged integrated circuit wafer. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 1 is a flow chart of a method for forming a ball bump provided in an embodiment of the present application.
[0028] Figure 2 It is a cross-sectional schematic diagram of a method for forming a ball bump provided in an embodiment of the present application.
[0029] Figure 3 Schematic diagram of a ball implant bump provided in an embodiment of the present application.
[0030] Figure 4 This is a schematic diagram of a process for forming a ball bump provided in an embodiment of the present application. Figure 1 .
[0031] Figure 5 This is a comparison diagram of a ball implant bump provided in an embodiment of the present application.
[0032] Figure 6This is a flow chart of a method for processing abnormal areas provided in an embodiment of the present application.
[0033] Figure 7 It is a flow chart of a method for processing a recessed area provided in an embodiment of the present application.
[0034] Figure 8 It is a flow chart of a method for processing a raised area provided in an embodiment of the present application.
[0035] Figure 9 This is a schematic diagram of a process for forming a ball bump provided in an embodiment of the present application. Figure 2 .
[0036] Figure 10 This is a flow chart of a flux printing method provided in an embodiment of the present application.
[0037] Figure 11 Schematic diagram of the structure of a ball bump forming system provided in an embodiment of the present application. DETAILED DESCRIPTION
[0038] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to Figures 1 to 11 and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.
[0039] The present application discloses a method for forming a ball bump. Figure 1 , the method comprising: Step S101: Covering the integrated circuit wafer with a first dielectric layer, wherein the first dielectric layer is provided with a first opening, and the first opening exposes the chip electrode of the integrated circuit wafer.
[0040] The integrated circuit wafer carries chip electrodes and corresponding circuit layouts. Furthermore, the surface of the integrated circuit wafer is covered with a passivation layer, which is provided with openings for exposing the front surface of the chip electrodes.
[0041] Optionally, the material of the first dielectric layer may be a low-temperature curing polymer material or a high-temperature curing polymer material.
[0042] The first dielectric layer can serve as a buffer protection layer for the integrated circuit wafer.
[0043] In some embodiments, a first dielectric layer is formed on the integrated circuit wafer by vapor deposition, the first dielectric layer completely covering the integrated circuit wafer, and the first dielectric layer is etched through a mask to form a first opening.
[0044] For example, please refer to Figure 2The integrated circuit wafer 201 is provided with a chip electrode 202 and a passivation layer 203 exposing the chip electrode 202 . A first dielectric layer 204 covers the passivation layer 203 , and a first opening in the first dielectric layer 204 exposes the chip electrode 202 .
[0045] Step S102: forming a redistribution layer at the first opening.
[0046] The redistribution layer is used to transfer the position of the pad (referring to the pins on the integrated circuit wafer) to achieve the rearrangement of the ball bumps.
[0047] Optionally, the redistribution layer is made of a conductive material.
[0048] For example, please refer to Figure 2 , a redistribution layer 205 is formed on the first opening to transfer the pad position.
[0049] Step S103: covering the redistribution layer with a second dielectric layer, wherein the second dielectric layer is provided with a second opening, and the second opening exposes a portion of the redistribution layer.
[0050] The first dielectric layer can be used as a buffer protection layer of the integrated circuit wafer to protect the redistribution layer.
[0051] In some embodiments, a second dielectric layer is formed on the redistribution layer by vapor deposition, and the second dielectric layer completely covers the redistribution layer. The second dielectric layer is etched through a mask to form a second opening.
[0052] For example, please refer to Figure 2 The second dielectric layer 206 covers the redistribution layer 205 , and the second opening on the second dielectric layer 206 exposes the redistribution layer 205 .
[0053] Step S104: transferring the transition layer having the bump pattern of the ball planting onto the second opening, wherein the bump pattern of the ball planting is a special shape.
[0054] Optionally, the transition layer is formed by using UBM (Under Bump Metallurgy, a packaging technology for forming a thin film at the connection between the chip and the substrate).
[0055] Optionally, a photoresist layer is applied to the second dielectric layer so that the photoresist layer covers the second dielectric layer. The photoresist layer is etched to form a third opening in the photoresist layer. The position of the third opening corresponds to the second opening in the second dielectric layer, and the opening shape of the third opening is a bump pattern. A transition layer is formed within the third opening through an electroplating process. The photoresist layer is removed.
[0056] For example, please refer to Figure 3The staggered arrangement of the bump patterns 301 on the integrated circuit wafer in this application reduces the size of the integrated circuit wafer in one direction, and the chip size can be flexibly adjusted by adjusting the staggered angle of the bumps. In contrast, the bump patterns 302 of the related art are neatly arranged on the integrated circuit.
[0057] For example, please refer to Figure 2 , transferring the transition layer 207 having the bump pattern to the second opening of the second dielectric layer 206 .
[0058] Step S105: forming ball-planting bumps on the transition layer through a ball-planting process, wherein the height of the ball-planting bumps is less than a preset height.
[0059] After the bumps are formed, the wafer is thinned through a thinning process. The integrated circuit wafer is then cut into individual chips, and each chip is flipped. The flipped chips are then placed through side strips using SMT (Surface Mounted Technology).
[0060] The preset height is the height of the bump having a regular pattern, wherein the regular pattern may be a circle.
[0061] For example, please refer to Figure 2 , solder balls 208 are placed on the transition layer 207, and solder bumps 209 are formed through a reflow process.
[0062] By adopting the above technical solution, special-shaped ball bumps are formed on the integrated circuit wafer. While ensuring that the bump area remains unchanged, the size of the integrated circuit wafer in one direction can be reduced. On the integrated circuit wafer of the same size, by setting special-shaped ball bumps, more chips can be produced at one time, thereby improving packaging efficiency.
[0063] In the following embodiment, when making ball bumps, it is necessary to pay extra attention to the thickness of the flux used in the reflow process and the placement of the solder balls. Therefore, the embodiment of the present application discloses a process diagram of a ball bump forming method. Figure 1 . Reference Figure 4 , the method comprising: Step S401: printing soldering flux on the transition layer.
[0064] Exemplarily, a flux screen is used for coating, the pattern portion on the flux screen is hollowed out, and the pattern portion corresponds to the position of the transition layer.
[0065] In some other embodiments, the soldering flux may also be formed by other methods such as spraying, dipping, thermal evaporation, and X-ray lithography.
[0066] It should be noted that the amount of flux can affect the quality of the bumps. If the flux is insufficient or applied unevenly, the solder balls will not be fully covered by the UBM (the transition layer in this application) during reflow, potentially causing flux depression, appearance abnormalities, and voids. If the flux is too high, overflow may occur, and the flux may extend beyond the UBM.
[0067] Step S402: placing a solder ball on the flux, wherein the size of the solder ball is smaller than the size of the transition layer.
[0068] Optionally, a solder ball stencil is used to place solder balls on the flux, with solder balls placed on each transition layer.
[0069] Step S403: melting the solder balls through a reflow process so that the solder corresponding to the solder balls fills the transition layer. The reflow process is performed at a preset temperature.
[0070] The reflow process is a soldering technique used in chip manufacturing and consists of four phases: 1. Preheating: Slow heating removes solvents and moisture from the flux, reduces thermal stress caused by temperature fluctuations, and protects the integrated circuit wafer. 2. Wetting: Heating to the flux's melting point melts the solder balls, forming liquid solder joints. 3. Reflow: Heating to the maximum temperature ensures complete melting of the solder and sufficient bonding with the underlying transition layer. 4. Cooling: Rapid cooling allows the molten solder balls to solidify, forming stable bumps.
[0071] The preset temperature in this step refers to the highest temperature in the reflow stage of the reflow process.
[0072] In this step, since the size of the solder ball is smaller than that of the transition layer, and the transition layer of this embodiment is larger than that of the related art, after the solder ball reflows, the diameter of the solder ball becomes larger and the height is lower than that of the related art, which can effectively reduce the size of the chip in the z direction.
[0073] Step S404: solidifying the melted solder through a reflow process to form ball bumps.
[0074] For example, please refer to Figure 5 Compared with the ball planting bump 210 formed by the related art, the ball planting bump 209 formed in the embodiment of the present application has a smaller height in the z direction. After the solder ball reflows, its diameter becomes larger and its height decreases, thereby reducing the size of the chip in the z direction. This provides a possibility for reducing the chip size. On the other hand, compared with the shorter bumps formed by the electroplating process, the shorter bumps formed by the ball planting process in the present application can determine the solder ball composition based on the finished solder ball, and the composition is more diverse, which can meet various performance requirements.
[0075] By adopting the above technical solution, when forming the ball bump, the size of the ball bump is controlled by the transition layer and the soldering flux, so that the effective area of the ball bump can meet the design requirements.
[0076] In the following embodiments, when printing the flux, the thickness of the flux needs to be strictly controlled to ensure the quality of the ball bumps. Therefore, the embodiment of the present application discloses a flow chart of a method for processing abnormal areas. Figure 6 , the method comprising: Step S601: Detecting the actual thickness of the soldering flux at various locations.
[0077] For example, the actual thickness of the soldering flux at various locations is determined by measuring the intensity of light reflected from the soldering flux surface.
[0078] For example, the actual thickness of the solder flux at each location is determined by measuring the absorption and reflection of polarized light by the solder flux.
[0079] Step S602: Compare the actual thickness with the preset thickness interval and filter out abnormal areas. The endpoints of the preset thickness interval include a preset minimum thickness value and a preset maximum thickness value. The abnormal area is a concave area or a convex area.
[0080] The thickness of the concave area is less than a preset minimum thickness, and the thickness of the convex area is greater than a preset maximum thickness.
[0081] Optionally, the area of the abnormal region is larger than a preset area.
[0082] In some embodiments, abnormal actual thicknesses that do not fall within a preset thickness range are screened out, coordinates of points corresponding to the abnormal actual thicknesses are determined, and the coordinates of the adjacent aforementioned points are counted into a set, and all the coordinates in the set are marked as abnormal areas.
[0083] Step S603: When the abnormal area is a sunken area, determine the target position in the abnormal area according to the shape of the abnormal area.
[0084] When the abnormal area is a recessed area, the amount of flux in the recessed area is small. During the reflow process, the molten solder ball will have insufficient fluidity after entering the recessed area, affecting the height of the ball bump in the recessed area.
[0085] For example, the gravity of the abnormal area is determined according to the shape of the abnormal area, and the position of the center of gravity is used as the target position.
[0086] In some other embodiments, if the abnormal region is located in the edge region of the transition layer, the area of the abnormal region is obtained; when the area of the abnormal region is greater than the preset maximum area, the position of the center of gravity of the abnormal region is used as the target position. When the area of the abnormal region is less than the preset maximum area, the offset distance is obtained based on the area of the abnormal region, and the offset distance is positively correlated with the area of the abnormal region. The center point of the transition layer and the line connecting the center point to the abnormal region are determined. On the aforementioned line, a point whose distance from the midline point is the offset distance is determined and used as the target position. On the other hand, the minimum distance from each point in the abnormal region to the edge of the transition layer is calculated. The maximum value of the minimum distances is taken. If the maximum value is less than the preset edge judgment value, it indicates that the abnormal region is located in the edge region of the transition layer. If the maximum value is greater than the preset edge judgment value, it indicates that the abnormal region is not located in the edge region of the transition layer.
[0087] Step S604: placing the solder ball at the target position.
[0088] In some embodiments, the solder balls are placed at the target locations by a ball placer.
[0089] Step S605: melting the solder balls at a first temperature through a reflow process, where the first temperature is greater than a preset temperature.
[0090] The first temperature refers to the highest temperature during the reflow stage of the reflow process.
[0091] The amount of flux released from the recessed area is low, resulting in poor flux flow during the reflow process. However, flux exhibits different fluidity at different temperatures, with increased fluidity exhibiting enhanced fluidity as the temperature rises. Therefore, in this step, the first reflow temperature is set above a preset temperature to improve flux fluidity and ensure that the molten solder balls can fully flow to all locations in the transition layer.
[0092] Step S606: When the abnormal area is a convex area, determine the target position within the circumference of the abnormal area according to the shape of the abnormal area.
[0093] In some embodiments, the center of gravity of the abnormal region is determined based on its shape. An offset distance is obtained based on the area of the abnormal region, and the offset distance is positively correlated with the area of the abnormal region. On the line connecting the center point of the abnormal region and the center of gravity, a point is determined that is the offset distance away from the center point in the direction away from the center of gravity, and is used as the target location.
[0094] In some embodiments, if the center point of the transition layer is located within the abnormal region, the center of gravity of the abnormal region is obtained, the midpoint of the line connecting the center point and the center of gravity is determined, and the location of the midpoint is used as the target location.
[0095] Step S607: placing the solder ball at the target position.
[0096] In some embodiments, the solder balls are placed at the target locations by a ball placer.
[0097] Step S608: melting the solder balls at a second temperature through a reflow process, where the second temperature is lower than a preset temperature.
[0098] The second temperature refers to the highest temperature in the reflow stage of the reflow process.
[0099] The amount of flux released from the raised areas is relatively low, resulting in excessive flux flow during the reflow process, which can easily cause overflow. However, as the temperature decreases, the flux's fluidity decreases. Therefore, in this step, the second reflow temperature is set lower than the preset temperature to reduce the flux's fluidity and prevent excessive flux flow.
[0100] By adopting the above technical solution, different methods are set for remedial treatment of abnormal areas of the flux, so that the abnormal areas will not affect the shape and size of the ball bumps, ensuring that the quality of the ball bumps meets the design requirements.
[0101] In the following embodiment, if the abnormal area is a concave area, there may be multiple concave areas, and in this case, the target position for placing the solder ball needs to be changed. Therefore, the embodiment of the present application discloses a flow chart of a method for processing a concave area. Figure 7 , the method comprising: Step S701: When the abnormal region belongs to a sunken region and there are at least two abnormal regions, clustering operation is performed on the abnormal regions to obtain clustered abnormal regions.
[0102] For example, a target abnormal region is randomly selected from the abnormal regions. The distance between the target abnormal region and other abnormal regions is calculated. If the distance is less than a preset classification distance, the corresponding abnormal region is included in the cluster of abnormal regions where the target abnormal region is located; if the distance is greater than the preset classification distance, the corresponding abnormal region is not included in the cluster of abnormal regions where the target abnormal region is located.
[0103] Exemplarily, abnormal regions within the same cluster of abnormal regions are merged.
[0104] Step S702: Determine whether the distance between clustered abnormal regions is less than a first preset distance.
[0105] If the distance between the clustered abnormal regions is less than the first preset distance, executing steps S703 to S706; If the distance between the clustered abnormal regions is not less than the first preset distance, steps S707 to S708 are executed.
[0106] Step S703: If yes, set the target position between the clustered abnormal areas.
[0107] Exemplarily, the shortest distance from the target location to each clustered abnormal region is the same.
[0108] For example, the center coordinates of each clustered abnormal region are obtained. A target point is determined based on the center coordinates, and the distance between the target point and the coordinates of each center point is the same. The location of the target point is determined as the target location.
[0109] Step S704: placing a solder ball at the target position, where the size of the solder ball is a standard size.
[0110] In some embodiments, the solder balls are placed on target locations by a ball planter.
[0111] Step S705: During the reflow process, monitoring the flow of the solder balls.
[0112] The flow condition is used to indicate the coverage area and flow speed of the solder ball in the molten state.
[0113] Step S706: When the solder balls flow to the cluster abnormal area, the cluster abnormal area is heated by laser, and the heating temperature of the laser is a preset first heating temperature.
[0114] In some embodiments, when it is monitored that the distance between the coverage area of the molten solder ball and the cluster abnormality area is less than a preset distance warning value, the cluster abnormality area is heated by laser to further increase the temperature of the cluster abnormality area and enhance the fluidity of the flux in the cluster abnormality area.
[0115] Step S707: If not, set the target position in each clustered abnormal area.
[0116] When the distance between the clustered abnormal regions is not less than the first preset distance, and the distance between each clustered abnormal region is relatively large, a target position is set within each clustered abnormal region, and a smaller solder ball is placed at the target position. When the solder balls at different target positions melt, the transition layer can be filled more evenly.
[0117] Step S708: placing a solder ball on each target position, where the size of the solder ball is smaller than the standard size.
[0118] In some embodiments, a solder ball is placed on each target location by a ball placer.
[0119] The sum of the volumes of all solder balls is the same as the volume of a standard-sized solder ball.
[0120] By adopting the above technical solution, when the abnormal area belongs to a recessed area, the abnormal area is clustered to obtain clustered abnormal areas, and a corresponding solution is selected for processing based on the distance between the clustered abnormal areas, thereby ensuring that the ball bumps generated on the recessed area meet the design requirements and improving the yield rate of packaged integrated circuit wafers.
[0121] In the following embodiment, if the abnormal area is a raised area, and there are multiple raised areas, the target position needs to be adjusted to ensure the quality of the ball bump. Therefore, the embodiment of the present application discloses a flow chart of a method for processing raised areas. Figure 8 , the method comprising: Step S801: when the abnormal area is a raised area and there are at least two abnormal areas, a target position is determined according to the position distribution of the abnormal areas on the flux, and the distance from the target position to each abnormal area is the same.
[0122] For example, if the abnormal region is a raised region and there are at least two abnormal regions, the positional distribution of the abnormal regions on the solder flux is obtained. Assume the coordinates of the target location. Based on the assumption that the distances from the target location to each abnormal region are the same, establish a system of equations. Solve the aforementioned system of equations to obtain the coordinates of the target location.
[0123] In some other embodiments, after determining the target position, the area of each abnormal region is calculated. The area is normalized to obtain a weight value. The weight distance of each abnormal region is obtained according to the product of the distance value from the target position to the abnormal region and the weight value. The target position is adjusted according to the weight distance so that the distance from the target position to the abnormal region matches the weight distance. Among them, the area is positively correlated with the weight value. The larger the area, the larger the weight value. At this time, the corresponding weight distance is also larger, and the farther the target position is from the abnormal region. In this embodiment, the larger the area of the abnormal region, the farther the target position is from the abnormal region. In the reflow process, the molten solder ball takes a longer time to flow to the abnormal region. Since the present embodiment needs to heat the abnormal region by laser to thin the abnormal region, extending the distance between the target position and the abnormal region can provide more time to thin the abnormal region, so that after the molten solder ball flows to the abnormal region, the thickness of the abnormal region is closer to the preset thickness range.
[0124] Step S802: placing a solder ball at a target position, where the size of the solder ball is a standard size.
[0125] In some embodiments, solder balls are placed at target locations by a ball placer.
[0126] Step S803: monitoring the flow of solder balls.
[0127] The flow condition is used to indicate the coverage area and flow speed of the solder ball in the molten state.
[0128] In some embodiments, a camera is used to capture a surface image of an integrated circuit wafer. The solder ball coverage area is identified from the surface image. Furthermore, the surface image is captured at predetermined time intervals, and the flow velocity is determined based on the change in coverage area between temporally adjacent surface images.
[0129] Step S804: During the reflow process, the abnormal area is heated by laser, and the heating temperature of the laser is a preset second heating temperature.
[0130] For example, during the soaking phase of the reflow process, the abnormal region is heated by laser so that the temperature rises faster than that of other regions. Furthermore, during the reflow phase of the reflow process, the laser heating region is continuously used so that the maximum temperature of the abnormal region is higher than that of other regions.
[0131] Step S805: When the distance between the solder ball and the abnormal region is less than a second preset distance, stop heating the abnormal region.
[0132] In this step, when the distance between the solder ball and the abnormal area is less than the second preset distance, it is necessary to stop heating the abnormal area. This is because the temperature will affect the process of the solder ball forming a bump. If the solder ball enters the abnormal area and is still heating the abnormal area, the flux in the abnormal area will be too fluid and glue overflow may occur. Therefore, it is necessary to stop heating the abnormal area in time when the solder ball approaches the abnormal area.
[0133] The second preset distance is a preset empirical value. In some embodiments, the second preset distance is related to the maximum temperature used in the reflow process during the reflow phase. The higher the maximum temperature, the larger the second preset distance. In other words, the second preset distance is positively correlated with the maximum temperature.
[0134] By adopting the above technical solution, when the abnormal area is a raised area, the target position for placing the solder ball is determined according to the position distribution of the abnormal area on the flux, and the abnormal area is heated during the reflow process to reduce the thickness of the abnormal area, so that the ball bumps generated on the raised area meet the design requirements, thereby improving the yield rate of the packaged integrated circuit wafer.
[0135] In the following embodiments, the abnormal area may include both a raised area and a recessed area. In this case, the flux in the raised area can flow into the recessed area to fill the recessed area. Therefore, the embodiment of the present application discloses a process diagram of a method for forming a bump. Figure 2 . Reference Figure 9 , the method comprising: Step S901: When the abnormal region includes a convex region and a concave region, the shortest distance between the convex region and the concave region is calculated.
[0136] If the abnormal region includes both convex and concave areas, for adjacent convex and concave areas, determine the target edge on the convex area that is closest to the concave area. Calculate the distance from the target edge to the concave area. The shortest distance between the convex and concave areas is taken as the shortest distance between the convex and concave areas.
[0137] Step S902: If the shortest distance is less than the third preset distance, the convex volume of the convex area and the concave volume of the concave area are calculated.
[0138] The third preset distance is a preset empirical value. The present embodiment does not limit the specific value of the third preset distance; personnel may adjust the value of the third preset distance based on actual needs. When the shortest distance is greater than the third preset distance, the distance between adjacent recessed and raised areas is too great, making it difficult for excess flux in the raised area to flow into the raised area.
[0139] In some embodiments, a first three-dimensional shape of a convex region is simulated. The first three-dimensional shape is segmented to obtain a plurality of regular three-dimensional shapes, where the regular three-dimensional shape includes at least one of a cube, a pyramid, and a sphere. The volumes of the plurality of regular three-dimensional shapes are summed to obtain the convex volume. Similarly, a second three-dimensional shape of a concave region is simulated. The second three-dimensional shape is segmented to obtain a plurality of regular three-dimensional shapes. The volumes of the plurality of regular three-dimensional shapes are summed to obtain the convex volume.
[0140] Step S903: During the reflow process, the convex region is heated in a heating order from an end close to the concave region to an end away from the convex and concave regions.
[0141] Optionally, during the wetting phase of the reflow process, the raised areas are heated with a laser, with the laser heating zone moving from the end closest to the recessed area to the end farther away from the recessed area. This causes the raised areas to heat up faster than other areas, increasing the fluidity of the flux in the raised areas and allowing it to flow into the recessed areas.
[0142] Step S904: If the convex volume is larger than the concave volume, then when it is detected that the concave volume is smaller than the first preset volume, heating of the convex area is stopped.
[0143] The first preset volume is a preset empirical value, and the embodiment of the present application does not limit the specific value of the first preset volume.
[0144] Under the premise that the volume of the protrusion is larger than the volume of the depression, when it is detected that the volume of the depression is smaller than the first preset volume, it means that a sufficient amount of soldering flux has flowed from the protrusion area to the depression area, and the heating of the protrusion area is stopped.
[0145] Step S905: If the convex volume is smaller than the concave volume, heating the convex area and the concave area is performed when it is detected that the convex volume is smaller than the second preset volume.
[0146] The second preset volume is a preset empirical value, and the embodiment of the present application does not limit the specific value of the second preset volume.
[0147] Optionally, a laser is used to heat the raised and recessed areas.
[0148] If the volume of the protrusion is smaller than the volume of the depression, then detecting that the volume of the protrusion is smaller than the second predetermined volume indicates that some flux in the protrusion has already flowed into the depression. However, the protrusion cannot provide sufficient flux to the depression, resulting in excess flux in the protrusion and insufficient flux in the depression. Therefore, both the protrusion and depression are heated simultaneously to further promote flux flow in both areas.
[0149] In some other embodiments, during the wetting phase of the reflow process, both the raised and recessed regions may be heated simultaneously to promote flux flow in both regions.
[0150] By adopting the above technical solution, when the abnormal area includes both a raised area and a recessed area, the corresponding processing method will be selected to solve the abnormal area according to the volume of the two abnormal areas, so that the ball bumps generated on the raised area meet the design requirements and improve the packaging efficiency of the integrated circuit wafer.
[0151] In the following embodiments, the thickness of the soldering flux needs to be strictly controlled during the printing process to ensure that the thickness of the soldering flux meets the design standards. Figure 10 , the method comprising: Step S1001: Obtain the position distribution of abnormal areas on the flux.
[0152] Optionally, the position distribution includes abnormal areas distributed at edge positions of the flux.
[0153] Optionally, the position distribution includes the abnormal regions being randomly distributed on the flux.
[0154] Optionally, the position distribution includes the abnormal areas being concentrated on the flux.
[0155] Step S1002: determining abnormal printing parameters according to the position distribution, where the abnormal printing parameters include at least one of the number of printing times, the printing direction, and the coating amount of a single printing.
[0156] In some embodiments, if the abnormal area is distributed at the edge of the flux, it means that the printing of the transition layer edge does not meet the design requirements when printing the flux. The printing direction and the single printing coating amount are used as abnormal printing parameters.
[0157] In some embodiments, if the abnormal areas are randomly distributed on the solder flux, the number of printing times, the printing direction, and the coating amount of a single printing are all used as abnormal printing parameters.
[0158] In some embodiments, if the abnormal areas are concentrated on the flux, the printing direction and the coating amount of a single printing are used as abnormal printing parameters.
[0159] Step S1003: Update abnormal printing parameters.
[0160] Optionally, the abnormal printing parameters are updated according to the distribution. For example, when the abnormal areas are concentrated on the solder flux, the printing direction is adjusted according to the location of the abnormal areas so that the adjusted printing direction passes through the concentrated distribution area of the abnormal areas.
[0161] Exemplarily, when the abnormal areas are randomly distributed on the flux, the number of printing times and the coating amount per single printing are adjusted, the number of printing times is increased and the coating amount per single printing is reduced, and the product of the number of printing times and the coating amount per single printing remains unchanged.
[0162] Step S1004: printing soldering flux according to the abnormal printing parameters to obtain updated soldering flux.
[0163] The abnormal printing parameters are updated according to the updated thickness and position distribution of the soldering flux, and the soldering flux is printed using the updated printing parameters to obtain an updated soldering flux.
[0164] Step S1005: updating abnormal printing parameters according to the updated thickness and position distribution of the soldering flux.
[0165] Illustratively, the abnormal printing parameters are updated based on the updated flux and position distribution.
[0166] By adopting the above technical solution, the abnormal printing parameters are updated according to the position distribution of the abnormal areas on the flux, and the occurrence of abnormal areas can be reduced in the subsequent printing process of the abnormal areas.
[0167] Based on the same invention concept, please refer to Figure 11 The present invention provides a bump forming system, comprising: An acquisition module 1101 is configured to acquire an integrated circuit wafer, solder flux, solder balls, actual thickness, a preset thickness range, a first preset distance, a second preset distance, a third preset distance, a first heating temperature, a second heating temperature, a first preset volume, and a second preset volume; Memory 1102, used to store a program of the ball bump forming method according to any one of the above embodiments; The processor 1103 can load and execute the program in the memory to implement the ball bump forming method as described in any one of the above embodiments.
[0168] In summary, by forming irregular ball bumps on the integrated circuit wafer, the size of the integrated circuit wafer in one direction can be reduced while ensuring that the bump area remains unchanged. On the integrated circuit wafer of the same size, by setting irregular ball bumps, more chips can be produced at one time, thereby improving packaging efficiency.
[0169] Those skilled in the art will clearly understand that for the sake of convenience and brevity, the division of the above-mentioned functional modules is only used as an example for illustration. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working processes of the above-mentioned systems, devices, and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0170] An embodiment of the present application provides a computer-readable storage medium storing a computer program that can be loaded by a processor and executed by a ball bump forming method.
[0171] Computer storage media include, for example, various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.
[0172] Based on the same inventive concept, an embodiment of the present application provides a smart terminal, including a memory and a processor, wherein the memory stores a computer program that can be loaded by the processor and execute a ball bump forming method.
[0173] Those skilled in the art will clearly understand that for the sake of convenience and brevity, the division of the above-mentioned functional modules is only used as an example for illustration. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. The specific working processes of the above-mentioned systems, devices, and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0174] The above are all preferred embodiments of the present application and are not intended to limit the scope of protection of this application. Unless otherwise specified, any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features. In other words, unless otherwise specified, each feature is merely an example of a series of equivalent or similar features.
Claims
1. A method for forming a ball bump, characterized in that: The method comprises: A first dielectric layer is covered on the integrated circuit wafer, wherein the first dielectric layer is provided with a first opening, and the first opening exposes the chip electrode of the integrated circuit wafer; forming a redistribution layer at the first opening; A second dielectric layer is covered on the rewiring layer, wherein the second dielectric layer is provided with a second opening, and the second opening exposes a portion of the rewiring layer; Transferring a transition layer having a bump pattern of ball planting to the second opening, wherein the bump pattern of ball planting is a special shape; Through the ball planting process, ball planting bumps are formed on the transition layer, and the height of the ball planting bumps is less than the preset height.
2. The method for forming a ball bump according to claim 1, wherein: The step of forming a ball planting bump on the transition layer through a ball planting process includes: printing solder flux on the transition layer; placing a solder ball on the solder flux, wherein the size of the solder ball is smaller than the size of the transition layer; Through a reflow process, the solder ball is melted so that the solder corresponding to the solder ball fills the transition layer, and the reflow process is performed at a preset temperature; The melted solder is solidified through the reflow process to form the ball bumps.
3. The method for forming a ball bump according to claim 2, wherein: The method further comprises: Detecting the actual thickness of the soldering flux at various locations; Comparing the actual thickness with a preset thickness interval, screening out an abnormal area, wherein the endpoints of the preset thickness interval include a preset minimum thickness value and a preset maximum thickness value, and the abnormal area is a concave area or a convex area; In the case where the abnormal area belongs to the sunken area, determining a target position within the abnormal area according to a shape of the abnormal area; placing the solder ball at the target position; Through the reflow process, the solder ball is melted at a first temperature, and the first temperature is greater than the preset temperature; In the case where the abnormal area belongs to the convex area, determining the target position within the circumference of the abnormal area according to the shape of the abnormal area; placing the solder ball at the target position; Through the reflow process, the solder ball is melted at a second temperature, and the second temperature is lower than the preset temperature.
4. The method for forming a ball bump according to claim 3, wherein: The method further comprises: When the abnormal region belongs to the depressed region and there are at least two abnormal regions, clustering operation is performed on the abnormal regions to obtain clustered abnormal regions; Determining whether the distance between the clustered abnormal regions is less than a first preset distance; If yes, setting the target position between the clustered abnormal regions; Placing the solder ball at the target position, wherein the size of the solder ball is a standard size; During the reflow process, monitoring the flow of the solder balls; When the solder ball flows to the cluster abnormal area, the cluster abnormal area is heated by laser, and the heating temperature of the laser is a preset first heating temperature; If not, setting the target location in each of the clustered abnormal areas; The solder ball is placed on each of the target positions, and the size of the solder ball is smaller than the standard size.
5. The method for forming a ball bump according to claim 3, wherein: The method further comprises: When the abnormal area belongs to the raised area and there are at least two abnormal areas, the target position is determined according to the position distribution of the abnormal areas on the soldering flux, and the distance from the target position to each abnormal area is the same; placing the solder ball at the target position, wherein the size of the solder ball is a standard size; monitoring the flow of the solder balls; In the reflow process, the abnormal area is heated by laser, and the heating temperature of the laser is a preset second heating temperature; When the distance between the solder ball and the abnormal region is less than a second preset distance, heating of the abnormal region is stopped.
6. The method for forming a ball bump according to claim 3, wherein: The method further comprises: In the case where the abnormal area includes the convex area and the concave area, calculating the shortest distance between the convex area and the concave area; If the shortest distance is less than a third preset distance, calculating a convex volume of the convex area and a concave volume of the concave area; In the reflow process, the convex region is heated in a heating order from an end close to the concave region to an end far from the convex region; If the volume of the protrusion is larger than the volume of the depression, then when it is detected that the volume of the depression is smaller than the first preset volume, the heating of the protrusion area is stopped; If the protrusion volume is smaller than the recessed volume, then when it is detected that the protrusion volume is smaller than a second preset volume, the protrusion area and the recessed area are heated.
7. The method for forming a ball bump according to claim 2, wherein: The method further comprises: Obtaining the position distribution of abnormal areas on the soldering flux; Determining abnormal printing parameters according to the position distribution, wherein the abnormal printing parameters include at least one of the number of printing times, the printing direction, and the coating amount of a single printing; updating the abnormal printing parameters; Printing the soldering flux according to the abnormal printing parameters to obtain an updated soldering flux; The abnormal printing parameters are updated according to the updated soldering flux thickness and the position distribution.
8. A ball implant bump forming system, characterized in that: The system comprises: An acquisition module, used to acquire an integrated circuit wafer, a solder flux, a solder ball, an actual thickness, a preset thickness interval, a first preset distance, a second preset distance, a third preset distance, a first heating temperature, a second heating temperature, a first preset volume, and a second preset volume; A memory for storing a program of the ball bump forming method according to any one of claims 1 to 7; The program in the memory can be loaded and executed by the processor to implement the ball bump forming method as claimed in any one of claims 1 to 7.
9. An intelligent terminal, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program which can be loaded by the processor and executes any one of the methods of claims 1 to 7.
10. A computer-readable storage medium, characterized in that: A computer program is stored which can be loaded by a processor and execute the method according to any one of claims 1 to 7.