Wafer electroplating method and wafer electroplating system
By detecting film thickness differences and adjusting current density and voltage in a wafer electroplating system, the problem of poor wafer surface uniformity was solved, achieving uniform coating thickness and reliable metal interconnects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-03-31
AI Technical Summary
As semiconductor technology nodes continue to evolve, the critical dimensions of interconnects continue to shrink. Existing electroplating processes result in poor uniformity on the wafer surface, affecting the uniformity of the plating thickness and the reliability of metal interconnects after electroplating.
By employing an auxiliary cathode plating unit and probe in the wafer electroplating system, the current density and voltage of the probe are adjusted by detecting the difference in film thickness between the non-wired area and the wired area, so as to achieve fine-tuning of the current in the wired area and ensure the uniformity of the coating thickness.
By dynamically adjusting the current density and voltage, uniformity of the coating thickness on the wafer surface was achieved, improving the reliability of the metal interconnects and facilitating the subsequent CMP process.
Smart Images
Figure CN121760034A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor manufacturing, and more specifically, to a wafer electroplating method and a wafer electroplating system. Background Technology
[0002] Semiconductor electroplating is a crucial step in semiconductor manufacturing, forming metal interconnects. This process primarily uses electrochemical methods to deposit metal materials (such as copper) into trenches or vias on the wafer surface, creating conductive lines to achieve electrical and signal connectivity between components within the chip. However, as semiconductor technology evolves and chip integration increases, the critical dimensions of interconnects continue to shrink. This trend not only demands superior conductivity and reliability from the metal filling narrower linewidths but also leads to more complex patterning features on the wafer surface. Under these circumstances, current electroplating processes are prone to resulting in poor wafer surface uniformity. Summary of the Invention
[0003] To overcome the technical problems mentioned in the above-mentioned technical background, this application provides a wafer electroplating method applied to a wafer electroplating system. The wafer electroplating system includes an electroplating unit, an auxiliary electroplating unit, and a control unit. The electroplating unit includes a cathode electroplating subunit, and the auxiliary electroplating unit includes an auxiliary cathode electroplating subunit. The cathode electroplating subunit is used to support a wafer. The wafer includes at least a first wafer and a second wafer with the same structure. The auxiliary cathode electroplating subunit is disposed on the side of the wafer away from the cathode electroplating subunit. The auxiliary cathode electroplating subunit includes a probe. A gap exists between the wafer and the probe. The wafer includes a non-wired region and a wired region. The probe is disposed corresponding to at least a portion of the wired region. The probe is connected to the control unit. The method includes: The electroplating unit is controlled to perform electroplating on the first wafer. After a preset first electroplating time, the thickness of the first film layer of the coating grown in the non-wire area of the first wafer and the thickness of the second film layer of the coating grown in the wire area are detected. The first current density corresponding to the coating grown in the traceless area is determined based on the first film thickness, and the second current density corresponding to the coating grown in the trace area is determined based on the second film thickness. The first current adjustment amount corresponding to the trace area is determined based on the first current density and the second current density. The probe is moved to contact the trace area corresponding to the second wafer, and a first adjustment voltage is determined based on the first current adjustment amount; The first adjustment voltage is applied to the probe to adjust the current in the trace area, and the electroplating unit is controlled to perform electroplating on the second wafer.
[0004] In one possible implementation, the wafer further includes a third wafer, and after the steps of applying the first adjustment voltage to the probe to adjust the current in the trace region and controlling the electroplating unit to perform electroplating on the second wafer, the method further includes: After the preset second electroplating time, the thickness of the third film layer of the coating grown in the non-wire area of the second wafer and the thickness of the fourth film layer of the coating grown in the wire area are detected. Determine the magnitude of the difference between the thickness of the third film layer and the thickness of the fourth film layer; When the difference between the thickness of the third film layer and the thickness of the fourth film layer is greater than the difference threshold, the third current density corresponding to the coating grown in the traceless region is determined based on the thickness of the third film layer, and the fourth current density corresponding to the coating grown in the trace region is determined based on the thickness of the fourth film layer. The second current adjustment amount corresponding to the trace area is determined based on the third current density and the fourth current density, and the second adjustment voltage is determined based on the second current adjustment amount; The second adjustment voltage is applied to the probe to adjust the current in the trace area on the third wafer, and the electroplating unit is controlled to perform electroplating on the third wafer. The above steps are repeated until the difference between the film thickness of the coating grown in the non-trace area of the electroplated wafer and the film thickness of the coating grown in the trace area is less than or equal to the difference threshold.
[0005] In one possible implementation, the wafer electroplating system further includes an electroplating tank unit, the electroplating tank unit including an electroplating tank bottom and an electroplating tank sidewall surrounding the bottom of the electroplating tank, the electroplating tank bottom and the electroplating tank sidewall enclosing a receiving space, the auxiliary electroplating unit and part of the electroplating unit being disposed within the receiving space, and prior to the step of controlling the electroplating unit to perform electroplating treatment on the first wafer, the method further includes: The auxiliary cathode electroplating subunit is fixed on the side of the cathode electroplating subunit near the bottom of the electroplating tank; The first wafer is fixed on the cathode electroplating subunit, wherein there is a gap between the probe of the auxiliary cathode electroplating subunit and the first wafer; Add the pre-prepared electroplating solution into the accommodating space.
[0006] In one possible implementation, the auxiliary cathode electroplating subunit further includes an auxiliary cathode ring, a conductive ring, and a first exchange membrane fixed within the auxiliary cathode ring. The conductive ring and the probe are embedded within the first exchange membrane. The conductive ring is connected to the probe and the auxiliary cathode ring, respectively. The control unit is connected to the auxiliary cathode ring. The step of applying the first adjustment voltage to the probe to adjust the current at the trace area and controlling the electroplating unit to perform electroplating on the second wafer includes: The control unit applies a first adjustment voltage to the conductive ring corresponding to the trace area via the auxiliary cathode ring, and acts on the trace area on the second wafer via the probe connected to the conductive ring, and controls the electroplating unit to perform electroplating on the second wafer.
[0007] In one possible implementation, the step of determining the first current density corresponding to the coating grown in the traceless region based on the first film thickness, and determining the second current density corresponding to the coating grown in the trace region based on the second film thickness, includes: The formulas for the first current density and the second current density are as follows:
[0008] in, This refers to either the first current density or the second current density. This indicates the thickness of the first film layer or the thickness of the second film layer. Represents stoichiometric coefficients. Denotes Faraday's constant. This indicates the density of the coating material. This indicates the duration of the first electroplating. This indicates the molar mass of the coating material.
[0009] This application also provides a wafer electroplating system, which includes an electroplating unit, an auxiliary electroplating unit, and a control unit; The electroplating unit includes a cathode electroplating subunit, and the auxiliary electroplating unit includes an auxiliary cathode electroplating subunit. The cathode electroplating subunit is used to support the wafer. The auxiliary cathode electroplating subunit is disposed on the side of the wafer away from the cathode electroplating subunit. The auxiliary cathode electroplating subunit includes a probe. There is a gap between the wafer and the probe, or the wafer is in contact with the probe. The wafer includes a traceless region and a traced region. The probe is disposed corresponding to at least a portion of the traced region. The probe is connected to the control unit and is used to adjust the current at the traced region corresponding to the probe.
[0010] In one possible implementation, the electroplating unit further includes an anode electroplating subunit and a power supply subunit, wherein one end of the power supply subunit is connected to the cathode electroplating subunit and the other end is connected to the anode electroplating unit; The cathode electroplating subunit includes a cathode ring and a cathode ring clamping part disposed on one side of the cathode ring, and the wafer is fixed inside the cathode ring; The auxiliary cathode electroplating subunit further includes an auxiliary cathode ring, a conductive ring, and a first exchange membrane fixed within the auxiliary cathode ring. The conductive ring and the probe are embedded within the first exchange membrane. The conductive ring is connected to the probe and the auxiliary cathode ring, respectively. The control unit is also connected to the auxiliary cathode ring.
[0011] In one possible implementation, the wafer electroplating system further includes: An electroplating tank unit includes an electroplating tank bottom and an electroplating tank sidewall surrounding the bottom of the electroplating tank, wherein the electroplating tank bottom and the electroplating tank sidewall enclose a receiving space. The auxiliary electroplating unit and part of the electroplating unit are disposed within the accommodating space, wherein the anode electroplating subunit is disposed near the bottom of the electroplating tank, and the cathode electroplating subunit is disposed on the side of the anode electroplating unit away from the bottom of the electroplating tank; The wafer electroplating system further includes a second exchange membrane disposed between the anode electroplating subunit and the cathode electroplating subunit.
[0012] In one possible implementation, the conductive ring includes a plurality of concentric conductive rings, wherein the center of the orthographic projection of the conductive ring on the bottom of the electroplating tank coincides with the center of the orthographic projection of the wafer on the bottom of the electroplating tank. The trace regions corresponding to the probes connected to the same conductive ring have the same structure.
[0013] In one possible implementation, the auxiliary cathode electroplating subunit further includes a connecting bump, which is embedded in the first exchange membrane and disposed near the edge of the first exchange membrane. One end of the connecting protrusion is connected to the conductive ring, and the other end is connected to the auxiliary cathode ring.
[0014] Based on any of the above aspects, the wafer electroplating method and system provided in this application embodiment firstly control the electroplating unit to perform electroplating treatment on a first wafer. Then, after a preset first electroplating time, the thickness of a first film layer grown in a non-wired area and the thickness of a second film layer grown in a wired area of the first wafer are detected. Next, a first current density corresponding to the film grown in the non-wired area is determined based on the first film layer thickness, and a second current density corresponding to the film grown in the wired area is determined based on the second film layer thickness. Then, a first current adjustment amount corresponding to the wired area is determined based on the first and second current densities. Next, a probe is moved to contact the corresponding wired area on the second wafer, and a first adjustment voltage is determined based on the first current adjustment amount. Finally, the current in the wired area is adjusted by applying the first adjustment voltage to the probe, and the electroplating unit is controlled to perform electroplating treatment on the second wafer. The above solution is based on the difference in film thickness between the traceless area and the trace area to adjust the current in the trace area during the next electroplating process by means of a probe, thereby ensuring the uniformity of wafer electroplating. Attached Figure Description
[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 A schematic diagram of a wafer after an electroplating process provided by existing technology; Figure 2 This is a schematic diagram of the structure of a wafer electroplating system provided in this embodiment; Figure 3 This is a flowchart of a wafer electroplating method provided in this embodiment; Figure 4 for Figure 2 A top view of part of the structure of the wafer electroplating system.
[0017] Icons: Wafer electroplating system-1; Wafer-2; Electroplating solution-3; Electroplating unit-10; Auxiliary electroplating unit-20; Cathode electroplating subunit-100; Cathode ring-101; Cathode ring clamping part-102; Anode electroplating subunit-110; Auxiliary cathode electroplating subunit-200; Probe-201; Auxiliary cathode ring-202; First exchange membrane-203; Conductive ring-204; Connecting bump-205; Electroplating tank unit-30; Electroplating tank sidewall-300; Electroplating tank bottom-310; Accommodation space-320; Second exchange membrane-40. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0019] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0021] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0022] It should be noted that, where there is no conflict, different features in the embodiments of this application can be combined with each other.
[0023] The inventors discovered through research that semiconductor electroplating is a crucial step in semiconductor manufacturing, forming metal interconnects. This process primarily uses electrochemical methods to deposit metal materials (such as copper) into trenches or vias on the surface of wafer 2, constructing conductive lines to achieve electrical and signal connectivity between components within the chip. However, with the continuous evolution of semiconductor technology nodes and the increasing integration of chips, the critical dimensions of interconnects are constantly shrinking. This trend not only requires the metal filled within narrower linewidths to possess excellent conductivity and reliability but also leads to more complex patterning features on the wafer 2 surface (i.e., the coexistence of trenches of different sizes, densities, and aspect ratios). Under these circumstances, current electroplating processes easily result in poor uniformity on the wafer 2 surface.
[0024] Specifically, in current electroplating processes, the deposition rate varies significantly across different regions due to the electric field concentration effect at the wafer 2 edge, differences in current density between different patterned areas, and the complexity of the wafer 2 patterning features. Please refer to... Figure 1 , Figure 1 A schematic diagram of wafer 2 after electroplating process provided by the prior art. Under the same electroplating process conditions, exemplarily, high trench density, smaller critical dimensions, and trenches located at the edge of wafer 2 (such as...) Figure 1 In the AA1 region, the thickness of the coating layer after filling is significantly higher than that of the coating layer after filling the unpatterned or low-density regions (e.g., Figure 1 (In the AA2 region). This can easily lead to significant differences in the film thickness of the plating layer after electroplating on the surface of wafer 2, affecting the uniformity of electroplating on wafer 2, and thus easily affecting the reliability of subsequent metal interconnects and the implementation of CMP processes.
[0025] In order to solve the aforementioned technical problems, the inventors have innovatively designed the following technical solutions, and the specific implementation scheme of this application will be described in detail below with reference to the accompanying drawings.
[0026] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a wafer electroplating system 1 provided in this embodiment. Please refer to... Figure 3 , Figure 3 This is a flowchart illustrating the steps of a wafer electroplating method provided in this embodiment. The wafer electroplating method is applied to a wafer electroplating system 1, which includes an electroplating unit 10, an auxiliary electroplating unit 20, and a control unit (not shown in the figure). In this embodiment, the electroplating unit 10 is used to perform electroplating processing on the wafer 2, and typically includes a cathode electroplating subunit 100, an anode electroplating subunit 110, and a power supply subunit (not shown in the figure). The negative terminal of the power supply subunit is connected to the cathode electroplating subunit 100, and the positive terminal is connected to the anode electroplating subunit 110.
[0027] In this embodiment, the auxiliary electroplating unit 20 is used to fine-tune the current in a local area on the surface of wafer 2. It includes an auxiliary cathode electroplating subunit 200, which supports wafer 2. Wafer 2 includes at least a first wafer and a second wafer with the same structure. The auxiliary cathode electroplating subunit 200 is located on the side of wafer 2 away from the cathode electroplating subunit 100. The auxiliary cathode electroplating subunit 200 includes a probe 201, and a gap exists between wafer 2 and probe 201. The gap between wafer 2 and probe 201 is less than 100 nanometers.
[0028] Wafer 2 includes a no-wire region and a wired region. The no-wire region of wafer 2 is the flat region of wafer 2, while the wired region is the patterned region of wafer 2, which typically contains trenches or vias of different sizes, densities, and aspect ratios. The wired region includes high-density wired regions and low-density wired regions. The structures of the wired and no-wire regions of both the first and second wafers are identical.
[0029] Probes 201 are configured to correspond to at least a portion of the trace area. For example, some probes 201 may correspond to high-density trace areas, and some probes 201 may correspond to low-density trace areas. The number, size, and distribution of probes 201 are not specifically limited here and need to be set according to the actual situation of wafer 2. Furthermore, probes 201 corresponding to trace areas of the same density are connected to the same conductive ring 204. Probes 201 are electrically connected to a control unit, which applies a first adjustment voltage to the probes 201 to adjust the current at the trace area corresponding to the probe 201.
[0030] In this embodiment, wafer 2 includes a plurality of uniformly distributed chip cells. A region with the same structure among the plurality of chip cells is a wiring region. A region with the same structure represents a region with the same pattern density and key size features.
[0031] It is worth noting that the power supply subunit in the electroplating unit 10 can be electrically connected to the control unit to control the power supply subunit to turn on or off.
[0032] The following is combined Figure 1 and Figure 2 The wafer electroplating method provided in the embodiments of this application will be described in detail.
[0033] Step S11: Control the electroplating unit 10 to perform electroplating treatment on the first wafer.
[0034] In this step, the electroplating unit 10 performs electroplating on the first wafer based on a preset electroplating process. At this time, the electroplating unit 10 is working, while the auxiliary electroplating unit 20 is not working.
[0035] In this embodiment, the purpose of this step is to obtain the actual coating growth status of the first wafer after the natural electroplating process. Taking the coating growth status on the first wafer in the non-wired area as a reference, if the difference in film thickness between the partially wired area and the non-wired area of the first wafer is large, it indicates that the current in this wired area needs to be adjusted to adjust the deposition rate of the coating material in this wired area.
[0036] Step S12: After the preset first electroplating time, the thickness of the first film layer of the coating grown in the non-wire area of the first wafer and the thickness of the second film layer of the coating grown in the wire area are detected.
[0037] In this step, the wafer electroplating system 1 also includes a film thickness measurement unit, which is connected to the control unit and is used to detect the first film thickness and the second film thickness of the first wafer. The second film thickness is the thickness of the coating grown on the surface of the first wafer at the wiring area, excluding the coating thickness filled by trenches or vias.
[0038] It is worth noting that the specific duration of the first electroplating time is not specifically limited here, but it is necessary to ensure that after the first electroplating time, a certain thickness of plating layer is deposited in both the trace area and the non-trace area of the first wafer, and that the trenches or vias in the trace area are filled at this time.
[0039] Step S13: Determine the first current density corresponding to the coating grown in the traceless area based on the first film thickness, and determine the second current density corresponding to the coating grown in the trace area based on the second film thickness.
[0040] In this embodiment, the control unit deduces the first current density in the traceless region based on the thickness of the first film layer. This first current density is the reference current density. The control unit deduces the second current density in the trace region based on the thickness of the second film layer. This second current density is the actual current density of the corresponding region.
[0041] Step S14: Determine the first current adjustment amount corresponding to the trace area based on the first current density and the second current density.
[0042] In this embodiment, the control unit determines the fine-tuning amount (i.e., the first current adjustment amount) corresponding to different trace regions by comparing the first current density and the second current density, which is to determine the amount of current that the probe 201 needs to shunt. For example, the amount of current shunted to the second wafer at the trace region is 5% of the original current, or the amount of current shunted to the second wafer at the trace region is 2% of the original current. The first current adjustment amount is not specifically limited here and needs to be set according to the actual situation.
[0043] Step S15: Move probe 201 to the corresponding trace area on the second wafer and determine the first adjustment voltage based on the first current adjustment amount.
[0044] In this step, the first electroplated wafer is removed from the cathode electroplating subunit 100, and the second wafer is fixed to the cathode electroplating subunit 100. The control unit controls the probe 201 to move to contact the second wafer. At this time, the probe 201 contacts the corresponding trace area on the second wafer as on the first wafer, and determines the first adjustment voltage to be applied to the probe 201 based on the first current adjustment amount.
[0045] In this embodiment, the auxiliary cathode electroplating subunit 200 can adjust the movement of the probe 201 by a spring so that the probe 201 contacts the second wafer.
[0046] Step S16: Apply a first adjustment voltage to probe 201 to adjust the current in the trace area, and control the electroplating unit 10 to perform electroplating on the second wafer.
[0047] In this embodiment, during the electroplating process of the second wafer, the control unit applies a first adjustment voltage to the probe 201 to divert part of the current in the trace area, thereby slowing down the deposition rate in the trace area. This adjusts the difference in film thickness between the trace area and the non-trace area, ensuring the uniformity of electroplating on wafer 2. At this time, electroplating unit 10 operates, and auxiliary electroplating unit 20 also operates.
[0048] Furthermore, wafer 2 also includes a third wafer, and after step S16, the method further includes: First, after the preset second electroplating time, the thickness of the third film layer of the coating grown in the non-wire area of the second wafer and the thickness of the fourth film layer of the coating grown in the wire area are detected.
[0049] In this step, the thickness of the fourth film layer is the thickness of the coating grown on the second wafer surface at the trace area, excluding the thickness filled by trenches or vias.
[0050] It is worth noting that the specific duration of the second electroplating time is not limited here. The key is to ensure that after the second electroplating time, a certain thickness of plating layer is deposited in both the trace and non-trace areas of the second wafer, at which point the trenches or vias in the trace areas are filled. The second electroplating time can be the same as the first electroplating time.
[0051] Next, determine the difference between the thickness of the third film layer and the thickness of the fourth film layer.
[0052] In this step, if the difference between the thickness of the third and fourth film layers is within a certain range (i.e., less than or equal to the difference threshold), it indicates that the film thickness of the coating in the non-wired area and the coating in the wired area on the second wafer is relatively uniform, and the electroplating process can be performed using the electroplating parameters of the second wafer. If the difference between the thickness of the third and fourth film layers is greater than the difference threshold, it indicates that the film thickness of the coating in the non-wired area and the coating in the wired area on the second wafer differs significantly, and further adjustment is required using probe 201.
[0053] Next, when the difference between the thickness of the third film layer and the thickness of the fourth film layer is greater than the difference threshold, the third current density corresponding to the coating grown in the traceless area is determined based on the thickness of the third film layer, and the fourth current density corresponding to the coating grown in the trace area is determined based on the thickness of the fourth film layer.
[0054] In this step, the third current density in the traceless region is deduced based on the thickness of the third film layer. This third current density is the reference current density. The fourth current density in the trace region is deduced based on the thickness of the fourth film layer. This fourth current density is the actual current density of the corresponding region.
[0055] Then, based on the third current density and the fourth current density, the second current adjustment amount corresponding to the trace area to be adjusted is determined, and the second adjustment voltage is determined based on the second current adjustment amount.
[0056] In this step, a second current adjustment amount for the trace region is determined by comparing a third current density and a fourth current density, and this second current adjustment amount is typically greater than the first current adjustment amount. For example, the amount of current shunted to the second wafer in the trace region is 20% of the original current, or the amount of current shunted to the second wafer in the trace region is 10% of the original current. The second current adjustment amount is not specifically limited here and needs to be set according to the actual situation.
[0057] Finally, a second adjustment voltage is applied to probe 201 to adjust the current in the trace area on the third wafer, and the electroplating unit 10 is controlled to perform electroplating on the third wafer. The above steps are repeated until the difference between the thickness of the coating grown in the non-trace area of the electroplated wafer 2 and the thickness of the coating grown in the trace area is less than or equal to the difference threshold.
[0058] In this step, during the electroplating process on the third wafer, a second adjustment voltage is applied to probe 201 to shunt a portion of the current in the trace area to be adjusted, thereby adjusting the difference in film thickness between the trace area and the non-trace area. At this time, the trace area that probe 201 contacts on the third wafer is the same as the trace area that contacts on the second wafer.
[0059] In this embodiment, if the difference in film thickness between the plating layer in the trace area and the plating layer in the non-trace area of the third wafer after electroplating is still greater than the difference threshold, the processing steps for the second or third wafer are repeated until the difference in film thickness between the plating layer grown in the non-trace area and the plating layer grown in the trace area of the electroplated wafer 2 is less than or equal to the difference threshold. At this point, the electroplating parameters of the electroplated wafer 2 can be used for subsequent electroplating processes to ensure the uniformity of electroplating on wafer 2, thereby ensuring the reliability of subsequent metal interconnects and the implementation of CMP processes.
[0060] Furthermore, please refer to again Figure 2The wafer electroplating system 1 also includes an electroplating tank unit 30, which includes an electroplating tank bottom 310 and an electroplating tank sidewall 300 surrounding the bottom 310. The bottom 310 and the sidewall 300 enclose a receiving space 320. The auxiliary electroplating unit 20 and part of the electroplating unit 10 are disposed within the receiving space 320. Before step S11, the method further includes: First, the auxiliary cathode electroplating subunit 200 is fixed on the side of the cathode electroplating subunit 100 near the bottom 310 of the electroplating tank.
[0061] In this step, ensure that the probe 201 of the auxiliary cathode plating sub-unit 200 is facing the cathode plating sub-unit 100.
[0062] In this embodiment, the spacing between the auxiliary cathode electroplating subunit 200 and the cathode electroplating subunit 100 is adjustable.
[0063] Next, the first wafer is fixed on the cathode electroplating subunit 100, wherein there is a gap between the probe 201 of the auxiliary cathode electroplating subunit 200 and the first wafer.
[0064] In this step, probe 201 does not contact the first wafer.
[0065] Finally, the pre-prepared electroplating solution 3 is added into the accommodating space 320.
[0066] In this step, electroplating solution 3 is smoothly injected into the accommodating space 320 to ensure that the electroplating solution 3 completely submerges the anode electroplating subunit 110, the auxiliary cathode electroplating subunit 200, and the first wafer.
[0067] Furthermore, please refer to again Figure 2 The auxiliary cathode electroplating subunit 200 also includes an auxiliary cathode ring 202, a conductive ring 204, and a first exchange membrane 203 fixed in the auxiliary cathode ring 202. The conductive ring 204 and the probe 201 are embedded in the first exchange membrane 203. The conductive ring 204 is connected to the probe 201 and the auxiliary cathode ring 202 respectively. The control unit is connected to the auxiliary cathode ring 202. Step S16 can be implemented in the following way.
[0068] The control unit applies a first adjustment voltage to the conductive ring 204 corresponding to the trace area via the auxiliary cathode ring 202, and acts on the trace area on the second wafer via the probe 201 connected to the conductive ring 204, and controls the electroplating unit 10 to perform electroplating on the second wafer.
[0069] In this step, the conductive ring 204 includes concentric conductive rings 204, the center of which in the orthographic projection of the concentric conductive ring 204 onto the bottom 310 of the electroplating tank coincides with the center of the orthographic projection of the second wafer onto the bottom 310 of the electroplating tank. The trace regions corresponding to probes 201 connected to a conductive ring 204 have the same structure. For example, at least some probes 201 corresponding to high-density trace regions are connected to the same conductive ring 204, and at least some probes 201 corresponding to low-density trace regions are connected to the same conductive ring 204.
[0070] In this embodiment, the auxiliary cathode ring 202 further includes a connecting conductive ring embedded on the side of the auxiliary cathode ring 202 facing the conductive ring 204, and the connecting conductive ring is connected to the control unit. The auxiliary cathode electroplating subunit 200 also includes a connecting bump 205, which is embedded in the first exchange membrane 203. One end of the connecting bump 205 is connected to the conductive ring 204, and the other end is connected to the connecting conductive ring, wherein the connecting conductive ring includes a plurality of contact points corresponding to the connecting bump. The control unit applies a first adjustment voltage to the contact points on the connecting conductive ring corresponding to the wiring area (i.e., the area where the difference between the second current density and the first current density is greater than the difference threshold). The first adjustment voltage is applied to the second wafer through the connecting bump 205 connected to the contact point, the conductive ring 204 connected to the connecting bump 205, and the probe 201 on the conductive ring 204.
[0071] Furthermore, step S13 can be implemented in the following way.
[0072] The formulas for expressing the first current density and the second current density are:
[0073] in, Indicates the first current density or the second current density. Indicates the thickness of the first film layer or the thickness of the second film layer. Represents stoichiometric coefficients. Denotes Faraday's constant. This indicates the density of the coating material. Indicates the first or second electroplating time. This indicates the molar mass of the coating material.
[0074] In this embodiment, when the electroplated metal is copper, the stoichiometric coefficient is... It can be 2, This indicates the density of copper. The molar mass of copper, Faraday constant. It can be 96498 C / mol.
[0075] It is worth noting that the values of the above parameters are not limited here and should be selected according to the actual situation. This indicates, but is not limited to, the thickness of the first film layer or the thickness of the second film layer. , express During either the first or second electroplating duration, the film thickness in this embodiment can be obtained using the above formula to determine the corresponding current density.
[0076] Based on the same inventive concept, this application also provides a wafer electroplating system 1, please refer again. Figure 2 The wafer electroplating system 1 includes an electroplating unit 10, an auxiliary electroplating unit 20, and a control unit. The electroplating unit 10 includes a cathode electroplating subunit 100, and the auxiliary electroplating unit 20 includes an auxiliary cathode electroplating subunit 200. The cathode electroplating subunit 100 is used to support the wafer 2, and the auxiliary cathode electroplating subunit 200 is located on the side of the wafer 2 away from the cathode electroplating subunit 100. In this embodiment, the electroplating unit 10 is used to perform electroplating on the wafer 2, and the auxiliary electroplating unit 20 is used to fine-tune the current in localized areas on the surface of the wafer 2.
[0077] The auxiliary cathode plating sub-unit 10 includes probes 201. A gap exists between the wafer 2 and the probes 201, or the wafer 2 is in contact with the probes 201. The wafer 2 includes a non-wired area and a wired area. The probes 201 are correspondingly disposed with at least a portion of the wired area. In this embodiment, the auxiliary cathode plating sub-unit 200 can control the movement of the probes 201 to bring them into contact with the wafer 2. The non-wired area of the wafer 2 is a flat area, and the wired area is a patterned area of the wafer 2, which has trenches or vias of different sizes, densities, and aspect ratios. Exemplarily, some probes 201 can be correspondingly disposed with wired areas of higher density, and some probes 201 can also be correspondingly disposed with wired areas of lower density. The number, size, and distribution of the probes 201 are not specifically limited here and need to be set according to the actual situation of the wafer 2.
[0078] The probe 201 is electrically connected to the control unit and is used to adjust the current at the trace area corresponding to the probe 201. In this embodiment, the wafer electroplating system 1 is used to implement the wafer electroplating method provided in the aforementioned embodiments of this application. Based on the difference in film thickness between the trace-free area and the trace area, the current at the trace area is adjusted by the probe 201 during the next electroplating process, thereby ensuring the uniformity of wafer electroplating.
[0079] Furthermore, please refer to again Figure 2 The electroplating unit 10 also includes an anode electroplating subunit 110 and a power supply subunit. One end of the power supply subunit is connected to the cathode electroplating subunit 100, and the other end is connected to the anode electroplating subunit 110. In this embodiment, the negative terminal of the power supply subunit is connected to the cathode electroplating subunit 100, and the positive terminal is connected to the anode electroplating subunit 110.
[0080] The cathode electroplating subunit 100 includes a cathode ring 101 and a cathode ring clamping portion 102 disposed on one side of the cathode ring 101, with the wafer 2 fixed inside the cathode ring 101. The auxiliary cathode electroplating subunit 200 also includes an auxiliary cathode ring 202, a conductive ring 204, and a first exchange membrane 203 fixed inside the auxiliary cathode ring 202. The conductive ring 204 and the probe 201 are embedded inside the first exchange membrane 203. The conductive ring 204 is connected to the probe 201 and the auxiliary cathode ring 202, respectively. The control unit is also connected to the auxiliary cathode ring 202.
[0081] In this embodiment, the cathode ring 101 and the auxiliary cathode ring 202 have the same shape, which can be square, rectangular, or circular. The auxiliary cathode ring 202 can be connected and fixed to the cathode ring 101 through threaded holes or other clamping means. The first exchange membrane 203 can be an ion exchange membrane, and a conductive ring 204 and a probe 201 can be fabricated in the first exchange membrane 203 by processes such as sputtering, evaporation, photolithography, or bonding.
[0082] It is worth noting that the conductive ring 204 can be made of titanium (Ti), copper (Cu), Pd, or metallized plastic, etc., and the outer side of the auxiliary cathode ring 202 is made of insulating material, such as ceramic or polymer coating (polytetrafluoroethylene or trifluorochloroethylene).
[0083] Furthermore, please refer to again Figure 2 The wafer electroplating system 1 also includes an electroplating tank unit 30, which includes an electroplating tank bottom 310 and an electroplating tank sidewall 300 surrounding the bottom 310. The bottom 310 and the sidewall 300 enclose a receiving space 320. An auxiliary electroplating unit 20 and part of the electroplating unit 10 are disposed within the receiving space 320. The anode electroplating subunit 110 is disposed near the bottom 310, and the cathode electroplating subunit 100 is disposed on the side of the anode electroplating subunit 110 away from the bottom 310. In this embodiment, the power supply subunit is typically disposed outside the receiving space 320. During the electroplating process, a pre-prepared electroplating solution 3 is added to the receiving space 320 to ensure that the electroplating solution 3 completely submerges the anode electroplating subunit 110, the auxiliary cathode electroplating subunit 200, and the wafer 2.
[0084] The wafer electroplating system 1 also includes a second exchange membrane 40, which is disposed between the anodic electroplating subunit 110 and the cathodic electroplating subunit 100. In this embodiment, the second exchange membrane 40 is a cation exchange membrane.
[0085] Further, please refer to Figure 4 , Figure 4 for Figure 2A top view of a portion of the structure of the wafer plating system 1. The conductive ring 204 comprises multiple concentric conductive rings, and the center of the orthographic projection of the conductive ring 204 onto the bottom 310 of the plating tank coincides with the center of the orthographic projection of the wafer 2 onto the bottom 310 of the plating tank. The trace structures corresponding to the probes 201 connected to the same conductive ring 204 are identical. For example, at least some probes 201 corresponding to high-density trace areas are connected to the same conductive ring 204, and at least some probes 201 corresponding to low-density trace areas are connected to the same conductive ring 204.
[0086] Further, please refer to Figure 2 The auxiliary cathode electroplating subunit 200 also includes a connecting protrusion 205, which is embedded in the first exchange membrane 203 and is located near the edge of the first exchange membrane 203. One end of the connecting protrusion 205 is connected to the conductive ring 204, and the other end is connected to the auxiliary cathode ring 202.
[0087] In this embodiment, the auxiliary cathode ring 202 further includes a connecting conductive ring embedded on the side of the auxiliary cathode ring 202 facing the wafer 2, and the connecting conductive ring is connected to the control unit. The auxiliary cathode electroplating subunit 200 also includes a connecting bump 205, which is embedded in the first exchange membrane 203. One end of the connecting bump 205 is connected to the conductive ring 204, and the other end is connected to the connecting conductive ring, wherein the connecting conductive ring includes a plurality of contact points corresponding to the connecting bump. Different conductive rings 204 are correspondingly arranged with the connecting bumps 205 and contact points.
[0088] In this embodiment, the control unit applies a first adjustment voltage to the contact point on the connecting conductive ring corresponding to the trace area. The first adjustment voltage is applied to the wafer via the connecting bump 205 connected to the contact point, the conductive ring 204 connected to the connecting bump 205, and the probe 201 on the conductive ring 204.
[0089] In summary, the wafer electroplating method and system provided in this application firstly control the electroplating unit to perform electroplating on a first wafer. Then, after a preset first electroplating time, the thickness of the first film layer grown in the non-wired region and the thickness of the second film layer grown in the wired region of the first wafer are detected. Next, a first current density corresponding to the film layer grown in the non-wired region is determined based on the first film layer thickness, and a second current density corresponding to the film layer grown in the wired region is determined based on the second film layer thickness. Then, a first current adjustment amount corresponding to the wired region is determined based on the first and second current densities. Next, a probe is moved to contact the corresponding wired region on the second wafer, and a first adjustment voltage is determined based on the first current adjustment amount. Finally, the current in the wired region is adjusted by applying the first adjustment voltage to the probe, and the electroplating unit is controlled to perform electroplating on the second wafer. This scheme, based on the difference in film thickness between the non-wired region and the wired region, enables the current adjustment in the wired region via a probe during the next electroplating process, thereby ensuring the uniformity of wafer electroplating.
[0090] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A wafer electroplating method, characterized in that, An application is made in a wafer electroplating system, the wafer electroplating system including an electroplating unit, an auxiliary electroplating unit, and a control unit. The electroplating unit includes a cathode electroplating subunit, and the auxiliary electroplating unit includes an auxiliary cathode electroplating subunit. The cathode electroplating subunit is used to support a wafer. The wafer includes at least a first wafer and a second wafer with the same structure. The auxiliary cathode electroplating subunit is disposed on the side of the wafer away from the cathode electroplating subunit. The auxiliary cathode electroplating subunit includes a probe. A gap exists between the wafer and the probe. The wafer includes a traceless region and a traced region. The probe is disposed corresponding to at least a portion of the traced region. The probe is connected to the control unit. The method includes: The electroplating unit is controlled to perform electroplating on the first wafer. After a preset first electroplating time, the thickness of the first film layer of the coating grown in the non-wire area of the first wafer and the thickness of the second film layer of the coating grown in the wire area are detected. The first current density corresponding to the coating grown in the traceless area is determined based on the first film thickness, and the second current density corresponding to the coating grown in the trace area is determined based on the second film thickness. The first current adjustment amount corresponding to the trace area is determined based on the first current density and the second current density. The probe is moved to contact the trace area corresponding to the second wafer, and a first adjustment voltage is determined based on the first current adjustment amount; The first adjustment voltage is applied to the probe to adjust the current in the trace area, and the electroplating unit is controlled to perform electroplating on the second wafer.
2. The wafer electroplating method as described in claim 1, characterized in that, The wafer further includes a third wafer. After the steps of applying the first adjustment voltage to the probe to adjust the current in the trace area and controlling the electroplating unit to perform electroplating on the second wafer, the method further includes: After the preset second electroplating time, the thickness of the third film layer of the coating grown in the non-wire area of the second wafer and the thickness of the fourth film layer of the coating grown in the wire area are detected. Determine the magnitude of the difference between the thickness of the third film layer and the thickness of the fourth film layer; When the difference between the thickness of the third film layer and the thickness of the fourth film layer is greater than the difference threshold, the third current density corresponding to the coating grown in the traceless region is determined based on the thickness of the third film layer, and the fourth current density corresponding to the coating grown in the trace region is determined based on the thickness of the fourth film layer. The second current adjustment amount corresponding to the trace area is determined based on the third current density and the fourth current density, and the second adjustment voltage is determined based on the second current adjustment amount; The second adjustment voltage is applied to the probe to adjust the current in the trace area on the third wafer, and the electroplating unit is controlled to perform electroplating on the third wafer. The above steps are repeated until the difference between the film thickness of the coating grown in the non-trace area of the electroplated wafer and the film thickness of the coating grown in the trace area is less than or equal to the difference threshold.
3. The wafer electroplating method as described in claim 1, characterized in that, The wafer electroplating system further includes an electroplating tank unit, which includes a bottom and sidewalls surrounding the bottom. The bottom and sidewalls enclose a receiving space. The auxiliary electroplating unit and part of the electroplating unit are disposed within the receiving space. Before the step of controlling the electroplating unit to perform electroplating on the first wafer, the method further includes: The auxiliary cathode electroplating subunit is fixed on the side of the cathode electroplating subunit near the bottom of the electroplating tank; The first wafer is fixed on the cathode electroplating subunit, wherein there is a gap between the probe of the auxiliary cathode electroplating subunit and the first wafer; Add the pre-prepared electroplating solution into the accommodating space.
4. The wafer electroplating method as described in claim 1, characterized in that, The auxiliary cathode electroplating subunit further includes an auxiliary cathode ring, a conductive ring, and a first exchange membrane fixed within the auxiliary cathode ring. The conductive ring and the probe are embedded within the first exchange membrane. The conductive ring is connected to the probe and the auxiliary cathode ring, respectively. The control unit is connected to the auxiliary cathode ring. The step of applying the first adjustment voltage to the probe to adjust the current at the trace area and controlling the electroplating unit to perform electroplating on the second wafer includes: The control unit applies a first adjustment voltage to the conductive ring corresponding to the trace area via the auxiliary cathode ring, and acts on the trace area on the second wafer via the probe connected to the conductive ring, and controls the electroplating unit to perform electroplating on the second wafer.
5. The wafer electroplating method as described in claim 1, characterized in that, The step of determining the first current density corresponding to the coating grown in the traceless region based on the first film thickness, and determining the second current density corresponding to the coating grown in the trace region based on the second film thickness, includes: The formulas for the first current density and the second current density are as follows: in, This refers to either the first current density or the second current density. This indicates the thickness of the first film layer or the thickness of the second film layer. Represents stoichiometric coefficients. Denotes Faraday's constant. This indicates the density of the coating material. This indicates the duration of the first electroplating. This indicates the molar mass of the coating material.
6. A wafer electroplating system, characterized in that, The wafer electroplating system includes an electroplating unit, an auxiliary electroplating unit, and a control unit; The electroplating unit includes a cathode electroplating subunit, and the auxiliary electroplating unit includes an auxiliary cathode electroplating subunit. The cathode electroplating subunit is used to support the wafer. The auxiliary cathode electroplating subunit is disposed on the side of the wafer away from the cathode electroplating subunit. The auxiliary cathode electroplating subunit includes a probe. There is a gap between the wafer and the probe, or the wafer is in contact with the probe. The wafer includes a traceless region and a traced region. The probe is disposed corresponding to at least a portion of the traced region. The probe is connected to the control unit and is used to adjust the current at the traced region corresponding to the probe.
7. The wafer electroplating system as described in claim 6, characterized in that, The electroplating unit further includes an anode electroplating subunit and a power supply subunit. One end of the power supply subunit is connected to the cathode electroplating subunit, and the other end is connected to the anode electroplating unit. The cathode electroplating subunit includes a cathode ring and a cathode ring clamping part disposed on one side of the cathode ring, and the wafer is fixed inside the cathode ring; The auxiliary cathode electroplating subunit further includes an auxiliary cathode ring, a conductive ring, and a first exchange membrane fixed within the auxiliary cathode ring. The conductive ring and the probe are embedded within the first exchange membrane. The conductive ring is connected to the probe and the auxiliary cathode ring, respectively. The control unit is also connected to the auxiliary cathode ring.
8. The wafer electroplating system as described in claim 7, characterized in that, The wafer electroplating system also includes: An electroplating tank unit includes an electroplating tank bottom and an electroplating tank sidewall surrounding the bottom of the electroplating tank, wherein the electroplating tank bottom and the electroplating tank sidewall enclose a receiving space. The auxiliary electroplating unit and part of the electroplating unit are disposed within the accommodating space, wherein the anode electroplating subunit is disposed near the bottom of the electroplating tank, and the cathode electroplating subunit is disposed on the side of the anode electroplating unit away from the bottom of the electroplating tank; The wafer electroplating system further includes a second exchange membrane disposed between the anode electroplating subunit and the cathode electroplating subunit.
9. The wafer electroplating system as described in claim 8, characterized in that, The conductive ring includes multiple concentric conductive rings, and the center of the orthographic projection of the conductive ring on the bottom of the electroplating tank coincides with the center of the orthographic projection of the wafer on the bottom of the electroplating tank. The trace regions corresponding to the probes connected to the same conductive ring have the same structure.
10. The wafer electroplating system as described in claim 9, characterized in that, The auxiliary cathode electroplating subunit also includes a connecting protrusion, which is embedded in the first exchange membrane and is located near the edge of the first exchange membrane. One end of the connecting protrusion is connected to the conductive ring, and the other end is connected to the auxiliary cathode ring.