Electroplating screen, electroplating apparatus, and gold electroplating method

Abstract

The application provides a kind of electroplating screen plate, electroplating equipment and gold plating method.The electroplating screen plate provided by the application includes plate body and a plurality of inserts, the plurality of inserts are arranged at intervals on the plate body, one end of the insert is free end, and the other end is rotatably connected with the plate body through the connecting piece.The electroplating screen plate of the application is applied in the electroplating equipment, and the stirring capacity of the electroplating screen plate can be adjusted by adjusting the inclination angle of the insert during the electroplating process according to the needs of electroplating, such as according to the density distribution of the to-be-electroplated circuit and the type of electroplating solution, thereby enhancing the plating solution exchange rate, changing the ion distribution in the electroplating solution to meet different electroplating needs.In addition, the optimal distance between the insert and the wafer can be adjusted according to the different plating solutions, which can effectively enhance the turbulence capacity of the screen plate, thereby improving the electroplating color difference problem, and effectively solving the problem of gold thickness uniformity abnormality.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, specifically to semiconductor electroplating technology, and particularly to an electroplating sieve, electroplating equipment, and gold electroplating method. Background Technology

[0002] Gold is a common precious metal material. Due to its good solderability, oxidation resistance and corrosion resistance, as well as its low contact resistance and good wear resistance, it is widely used in the field of semiconductor packaging technology, such as for surface treatment of packaging substrates and the production of metal bumps.

[0003] With the development of semiconductor packaging technology, gold plating technology has made significant progress. However, packaging anomalies caused by color difference in gold plating are still emerging, and this issue needs further improvement. This is because the gold bump surface has very high requirements for the electroplating process during packaging. Poor color difference and thickness uniformity on the gold surface can lead to a decrease in production yield. In addition, color difference on the gold bump surface can easily cause abnormalities such as failure to wire bond or peeling in subsequent processes. Through extensive research, the inventors discovered that the main causes of color difference in electroplated gold layers include: the current and electric field distribution in the wafer edge region is relatively concentrated (edge ​​and tip effects cause the corners to be denser than the center), which easily leads to increased current density at the wafer edge. This results in a rough gold bump lattice at the edge, a blackish appearance, and uneven current density distribution, which can easily lead to abnormal gold thickness uniformity and other problems.

[0004] To improve the uniformity of electroplating, existing electroplating equipment includes electroplating screens for stirring. These screens agitate the electroplating solution during the electroplating process, thereby improving the uniformity of the plating layer. A common type of electroplating screen is... Figure 1 As shown, it includes a rectangular plate with multiple grooves spaced apart on it. In other words, this electroplating sieve is integrally formed, with fixed groove slopes (typically 50°), spacing between adjacent grooves (typically 10mm), and distance between the sieve and the wafer (typically 7mm). This limits its use to stirring in a fixed direction within a specific electroplating solution, resulting in relatively weak stirring and turbulence capabilities, making it difficult to meet the ever-increasing and more stringent electroplating requirements.

[0005] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating understanding by those skilled in the art. It should not be assumed that these technical solutions are known to those skilled in the art simply because they have been described in the background section of this application. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an electroplating sieve, electroplating equipment, and gold electroplating method to solve the problems in the prior art, such as the concentrated distribution of current and electric field lines in the wafer edge region leading to increased current density at the wafer edge, rough gold bump lattice at the edge, black appearance, and uneven current density distribution resulting in abnormal gold thickness uniformity, thus causing poor encapsulation. Furthermore, existing electroplating sieves, due to fixed parameters such as slope and distance from wafer spacing, can only stir in a specific direction, resulting in weak stirring and turbulence capabilities, which are difficult to meet increasingly stringent electroplating requirements.

[0007] To achieve the above and other related objectives, the present invention provides an electroplating screen plate, which includes a plate body and a plurality of inserts. The plurality of inserts are arranged at intervals on the plate body, with one end of each insert being a free end and the other end being rotatably connected to the plate body via a connector.

[0008] Optionally, the plate body has an inverted triangle structure.

[0009] Optionally, the connector includes a cylindrical joint.

[0010] Optionally, the number of inserts is 9, and the inserts are evenly spaced.

[0011] Optionally, the spacing between the inserts is 30mm, the width of the inserts is 18mm, and the total thickness of the electroplating screen is 25mm.

[0012] Optionally, the plate and insert are made of PVC board, and the connector is made of titanium.

[0013] The present invention also provides an electroplating apparatus, the electroplating apparatus comprising an electroplating tank and an electroplating screen as described in any of the above embodiments, the electroplating screen being located within the electroplating tank.

[0014] Optionally, the electroplating screen plate is connected to a rotating shaft. During the electroplating process, the rotation of the rotating shaft can drive the rotation of the electroplating screen plate, thereby changing the distance between the insert and the electroplated part.

[0015] The present invention also provides a gold electroplating method, wherein the gold electroplating method is based on the electroplating equipment described in any of the above embodiments, and the gold electroplating method includes the step of changing the tilt angle of the insert during the electroplating process to change the stirring capacity of the electroplating screen plate.

[0016] Optionally, the gold electroplating method further includes the step of changing the distance between the electroplating screen and the workpiece during the electroplating process.

[0017] As described above, the electroplating sieve, electroplating equipment, and gold electroplating method of the present invention have the following beneficial effects: When the electroplating sieve of the present invention is applied to an electroplating equipment, the stirring ability of the sieve can be adjusted during the electroplating process by adjusting the tilt angle of the inserts, according to electroplating needs, such as the density distribution of the lines to be electroplated and the type of electroplating solution. This enhances the exchange rate of the plating solution and changes the ion distribution in the plating solution to meet different electroplating requirements. Furthermore, the optimal distance between the inserts and the wafer can be adjusted according to different plating solutions, effectively enhancing the turbulence-enhancing ability of the sieve, thereby improving the electroplating color difference problem and effectively solving problems such as abnormal gold thickness uniformity. Attached Figure Description

[0018] Figure 1 The diagram shown is an exemplary structural schematic of an electroplating screen plate in the prior art.

[0019] Figure 2 The diagram shown is an exemplary structural schematic of the electroplating screen plate provided by the present invention.

[0020] Figure 3 The diagram shown is a structural schematic of the insert of the electroplating screen plate of the present invention.

[0021] Figure 4 Displayed as Figure 2 A schematic diagram of the cross-sectional structure from the direction of line AA'.

[0022] Figure 5 The diagram shown is an exemplary structural schematic of the electroplating equipment provided by the present invention. Detailed Implementation

[0023] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. For ease of explanation, when detailing the embodiments of the present invention, the cross-sectional views showing the device structure are partially enlarged, not according to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0024] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0025] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0026] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components related to the present invention and are not drawn according to the actual number, shape, and size of the components in the actual implementation. In the actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex. To keep the illustrations as concise as possible, not all structures are shown in the figures.

[0027] like Figure 2 As shown, the present invention provides an electroplating screen plate 11 for use in electroplating equipment. The electroplating screen plate 11 includes a plate body 111 and a plurality of inserts 112. The main body shape of the inserts 112 can be rectangular, and its four corners are preferably rounded, which helps to improve the uniformity of electroplating solution distribution and avoid local turbulence. The plurality of inserts 112 are arranged at intervals on the plate body 111, and preferably are arranged in parallel and uniformly spaced, that is, the distance between any two adjacent inserts 112 is the same. One end of the insert 112 is a free end, and the other end is rotatably connected to the plate body 111 through a connector. That is, one end of the insert 112 is connected to the plate body 111, and the other end is not connected to other structures, so that the insert 112 can rotate around its connection point with the plate body 111, thereby changing the tilt angle of the insert 112.

[0028] Applying the electroplating sieve plate of this invention to electroplating equipment allows for adjustment of the sieve plate's stirring capacity during the electroplating process by adjusting the tilt angle of the inserts, based on electroplating requirements such as the density distribution of the lines to be plated and the type of electroplating solution. This enhances the exchange rate of the plating solution and alters the ion distribution within the solution to meet diverse electroplating needs. Furthermore, the optimal distance between the inserts and the wafer can be adjusted according to different plating solutions, effectively enhancing the sieve plate's turbulence-enhancing capabilities. This improves electroplating color difference issues and effectively solves problems such as abnormal gold thickness uniformity.

[0029] The plate 111 can be any structure suitable for fixing the inserts 112. In a preferred example, the plate 111 is a U-shaped structure, that is, the plate 111 has a half-enclosed space in which the inserts 112 are disposed. The outermost two inserts 112 are surrounded by the plate 111 structure, and the free ends of the inserts 112 face the opening direction of the space. Therefore, all the inserts 112 move within the space defined by the plate 111, which can prevent the inserts 112 from flying out due to accidental circumstances.

[0030] The plate 111 and the inserts 112 can be rotatably connected using various types of connectors. In one example, the connector includes a cylindrical joint, through which each insert 112 is connected to the plate 111. The cylindrical joint can be electrically connected to a drive mechanism such as a rotary motor via bearings or other connectors. The drive mechanism can be further connected to a controller, which can preset rotation parameters (such as rotation angle, rotation speed, and time) according to electroplating requirements. During electroplating, the controller controls the rotation of the drive mechanism according to the preset parameters (for example, controlling the rotation axis of the drive mechanism to reciprocate left and right, thereby causing the inserts 112 to swing left and right, i.e., the rotation angle of the inserts 112 is 0°-180°), thus driving the inserts 112 to rotate to meet different electroplating requirements. All inserts 112 can be connected to the same motor for synchronous control, which has the advantage of a relatively simple overall equipment structure. In other examples, different inserts 112 can also be connected to different motors to achieve independent control. For example, since the device distribution density at the center of the wafer is usually greater than that at the edge, the electroplating lines are also denser. Therefore, the swing speed of the insert 112 below the center of the wafer can be increased during the electroplating process to enhance the electroplating solution exchange capacity of the corresponding area.

[0031] The number of inserts 112 can be determined based on their size, the size of the wafer to be plated, etc. In a preferred example, there are nine inserts 112, which are evenly spaced. This number setting can basically meet the electroplating needs of wafers of various sizes on the market. Alternatively, even if the size of the electroplating screen 11 is larger than the wafer size, during the electroplating process, only the inserts 112 below the corresponding wafer can be rotated to adapt the effective working area of ​​the screen to the wafer size. Therefore, separately controlling the inserts 112 can not only meet the electroplating needs of wafers of different sizes, but also meet the electroplating needs of different areas within a single wafer, greatly improving the adaptability of the electroplating screen 11.

[0032] The dimensions and spacing of the inserts 112 must be set to ensure that the different inserts 112 do not interfere with each other during rotation. In a preferred example, the spacing between the inserts 112 is 30mm, the width H1 of the inserts 112 is 18mm, and the total thickness H2 of the electroplating screen plate 11 is 25mm.

[0033] Both the plate 111 and the insert 112 are made of insulating materials to prevent interference with the current distribution during electroplating. In a preferred example, both can be PVC boards, which are corrosion-resistant, have good mechanical strength, and are easy to process and shape. The connector is preferably made of the same material as the anode plate 15 of the electroplating equipment, such as titanium, but is not limited to this. Titanium has good corrosion resistance and excellent fatigue toughness, which can improve the service life of the connector.

[0034] This invention can be applied to different types of plating solutions and different electroplating machines for specific electroplating screen plates 11, and can be conveniently and quickly matched to diverse product designs through system program control.

[0035] like Figure 5 As shown, the present invention also provides an electroplating apparatus, which includes an electroplating tank 12 for holding the electroplating solution and an electroplating screen 11 as described in any of the above embodiments, the electroplating screen 11 being located within the electroplating tank 12. The foregoing description of the electroplating screen 11 is quoted in its entirety here and will not be repeated. More specifically, the electroplating screen 11 is located between the workpiece to be plated, for example, between the wafer 14 and the anode plate 15 (the anode plate 15 is typically located at the bottom of the electroplating tank 12). The electroplating screen 11 can be appropriately fixed within the electroplating tank 12. For example, in one example, the electroplating screen 11 is connected to a rotating shaft via a sheet metal part, so that during the electroplating process, the rotation of the rotating shaft can drive the rotation of the electroplating screen 11, thereby changing the vertical distance between the insert 112 and the workpiece to be plated.

[0036] The surface of wafer 14 to be plated faces the anode plate 15, while the free end of the insert 112 faces the surface of wafer 14 to be plated. In addition to the aforementioned electroplating tank 12 and electroplating sieve 11, the electroplating equipment may further include a clamping device 13 for holding wafer 14. The clamping device 13 includes, for example, a base and a vacuum chuck, and wafer 14 is fixed to the base by the suction of the vacuum chuck. The base may be connected to a driving device 16, such as a cylinder, to drive the base up and down and / or rotate as needed, thereby changing the position of wafer 14 relative to the electroplating liquid surface. In other examples, the electroplating sieve 11 and / or the electroplating tank 12 may also be connected to a lifting device, which moves up and down to change the spacing between them relative to wafer 14. For example, driving the electroplating screen 11 up and down changes the distance between the electroplating screen 11 and the wafer 14 (this distance is generally less than 7mm, but generally not less than 2mm, preferably 4mm), which can change the turbulence capability of the electroplating screen 11 to further improve the electroplating uniformity.

[0037] In some other examples, the electroplating equipment may also include a flow-stirring device (not shown) disposed between the electroplating screen 11 and the anode plate 15. This flow-stirring device may be, for example, a liquid injection pipeline through which new liquid is injected into the electroplating tank 12 during the electroplating process, and stirred by the electroplating screen 11 to further improve the distribution of metal ions in the electroplating solution, thereby further improving the electroplating uniformity.

[0038] In other examples, a cation exchange membrane (not shown) can be provided between the anode plate 15 and the electroplating screen plate 11. The membrane can be fixed in the electroplating tank by a support structure located around the membrane. The support structure is provided with a sealing ring around its circumference, thereby dividing the plating solution in the electroplating tank 12 into upper and lower layers. The surface unevenness distribution of the membrane can be adjusted by adjusting the support structure (e.g., stretching the support structure) to adjust the electric field distribution in the electroplating solution, thereby further improving the electroplating uniformity.

[0039] The electroplating equipment may further include a waste liquid collection tank (not shown), which is located around the electroplating tank, or in other words, the electroplating tank is located inside the waste liquid collection tank. Waste liquid generated during wafer wetting and / or electroplating solution overflowing during the electroplating process flows into the waste liquid collection tank.

[0040] The electroplating equipment provided by this invention can be used in various electroplating operations, and its advantages are particularly prominent when used in semiconductor gold plating processes. Because the gold plating layer has extremely high requirements for electroplating uniformity, once the electroplating is uneven, color differences are easily generated on the surface of the gold layer, affecting subsequent processes such as wire bonding. Therefore, the equipment provided by this invention is especially suitable for electroplating.

[0041] This invention also provides a gold electroplating method, which is based on the electroplating equipment described in any of the above-mentioned schemes. Therefore, the foregoing description of the electroplating equipment can be quoted in its entirety here, and will not be repeated for the sake of brevity. When using the electroplating equipment provided by this invention, the most significant difference between the gold electroplating method provided by this invention and the prior art lies in the step of changing the tilt angle of the inserts during the electroplating process to change the stirring capacity of the electroplating screen. For example, during the electroplating process, the inserts are driven to swing left and right; all inserts can swing simultaneously in the same direction, or in different directions, or some inserts may swing while others remain stationary, depending on the electroplating requirements. Furthermore, the gold electroplating method can also change the distance between the electroplating screen and the workpiece during the electroplating process, for example, by driving the workpiece (e.g., a wafer) and / or the electroplating screen to move up and down via a driving device. In addition, depending on the electroplating requirements, the electroplating tank can also be driven to move up and down during the electroplating process to change the distance between the workpiece and the anode plate, thereby changing the potential between the anode and cathode, further satisfying different electroplating needs.

[0042] Currently, the inventor has applied this electroplating equipment to the gold plating process in their factory. Addressing the issue of color difference in gold bumps, corresponding parameters were developed based on this equipment, and 15 different product models have been tested. Extensive data confirms that all models effectively improve gold color difference and thickness uniformity.

[0043] In summary, this invention provides an electroplating screen, electroplating equipment, and a gold electroplating method. The electroplating screen provided by this invention includes a plate body and multiple inserts. The inserts are arranged at intervals on the plate body, with one end of each insert being a free end and the other end rotatably connected to the plate body via a connector. Applying the electroplating screen of this invention to an electroplating equipment allows for adjustment of the screen's stirring capacity during the electroplating process by adjusting the tilt angle of the inserts, based on electroplating requirements such as the density distribution of the lines to be plated and the type of electroplating solution. This enhances the exchange rate of the plating solution and alters the ion distribution within the solution to meet different electroplating needs. Furthermore, the optimal distance between the inserts and the wafer can be adjusted according to different plating solutions, effectively enhancing the screen's turbulence-enhancing ability, thereby improving electroplating color difference issues and effectively solving problems such as abnormal gold thickness uniformity.

[0044] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0045] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An electroplating sieve plate, characterized in that, The electroplating screen plate includes a plate body and multiple inserts. The multiple inserts are arranged at intervals on the plate body. One end of each insert is a free end, and the other end is rotatably connected to the plate body through a connector. During the electroplating process, the connector is electrically connected to the drive mechanism, the drive mechanism is connected to the controller, and the controller is used to control the rotation of the drive mechanism. The insert rotates under the drive of the drive mechanism.

2. The electroplating sieve plate according to claim 1, characterized in that, The plate has an inverted triangle shape.

3. The electroplating sieve plate according to claim 1, characterized in that, The connector includes a cylindrical joint.

4. The electroplating sieve plate according to claim 1, characterized in that, The number of inserts is 9, and the inserts are evenly spaced.

5. The electroplating sieve plate according to claim 1, characterized in that, The spacing between the inserts is 30mm, the width of the inserts is 18mm, and the total thickness of the electroplating screen is 25mm.

6. The electroplating sieve plate according to claim 1, characterized in that, The plate and insert are made of PVC board, and the connector is made of titanium.

7. An electroplating device, characterized in that, The electroplating equipment includes an electroplating tank and an electroplating screen as described in any one of claims 1 to 6, wherein the electroplating screen is located inside the electroplating tank.

8. The electroplating equipment according to claim 7, characterized in that, The electroplating screen plate is connected to the rotating shaft. During the electroplating process, the rotation of the rotating shaft can drive the rotation of the electroplating screen plate, thereby changing the distance between the insert and the electroplated part.

9. A gold electroplating method, characterized in that, The gold electroplating method is performed using the electroplating equipment according to any one of claims 7 or 8, and the gold electroplating method includes the step of changing the tilt angle of the insert during the electroplating process to change the stirring capacity of the electroplating screen plate.

10. The electroplating method according to claim 9, characterized in that, The gold electroplating method also includes the step of changing the distance between the electroplating screen and the electroplated part during the electroplating process.

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